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At least 1,729 records · Page 96Linked to original sources
USGS2016

Development of working hypotheses linking management of the Missouri River to population dynamics of Scaphirhynchus albus (pallid sturgeon)

This report documents a process of filtering of hypotheses that relate Missouri River Scaphirhynchus albus (pallid sturgeon) population dynamics to management actions including flow alterations, channel reconfigurations, and pallid sturgeon population augmentation. The filtering process was a partnership among U.S. Geological Survey, U.S. Army Corps of Engineers, and U.S. Fish and Wildlife Service to contribute to the Missouri River Recovery Management Plan process. The objective of the filtering process was to produce a set of hypotheses with high relevance to pallid sturgeon population dynamics and decision making on the Missouri River. The Missouri River Pallid Sturgeon Effects Analysis team filtered hundreds of potential hypotheses implicit in conceptual ecological models to develop a set of 40 candidate dominant hypotheses that were identified by experts as being important in pallid sturgeon population dynamics. Using a modified Delphi process and additional expert opinion, the team reduced this set of hypotheses to 23 working dominant hypotheses. We then matched the 23 hypotheses with management actions that could influence the biotic outcomes, resulting in as many as 176 potential effects between management actions and pallid sturgeon in the Missouri River. This number was consolidated to a candidate set of 53 working management hypotheses because some management actions applied to multiple life stages of the pallid sturgeon. We used an additional round of expert surveys to identify a set of 30 working management hypotheses. Finally, the set of working management hypotheses was filtered by the U.S. Army Corps of Engineers, Missouri River Recovery Program for actions that were within the agency’s authority and jurisdiction. This round resulted in a set of 21 hypotheses for initial modeling of linkages from management to pallid sturgeon population responses. The initial set of candidate hypotheses provides a useful starting point for quantitative modeling and adaptive management of the river and species. We anticipate that hypotheses will change from the set of working management hypotheses as adaptive management progresses. More importantly, hypotheses that have been filtered out of our multistep process are still being considered. These filtered hypotheses are archived and if existing hypotheses are determined to be inadequate to explain observed population dynamics, new hypotheses can be created or filtered hypotheses can be reinstated.

Missouri River Basin↗
USGS2021

Grassland live fractional cover map creation and Geographic Information System (GIS) analysis for rangeland management supporting Kenya Northern Rangelands Trust Conservancies

The handbooks and synchronized MP4 recordings provide hands-on instruction for creating and analyzing vegetation live fractional cover (LFC) maps. The methods and protocols used in the instruction materials follow those developed and recorded in Rangoonwala and Ramsey (2019). The LFC mapping and geographic information system (GIS) analyses highlight the consortium of rangeland conservancies covering the semiarid central region of Kenya (approximately 44,000 square kilometers). The instruction materials are separated into two parts: processing and map-product creation based on remote-sensing images and GIS analyses of the created maps for rangeland management. The image processing is conducted using the advanced and professional software package SeNtinels Application Platform (SNAP) that is supported and maintained by the European Space Agency. SNAP is a free image analyses software package available for download. It is largely icon driven but offers simple to advanced program inserts and batch processing. The GIS analyses are conducted using the software package Quantum Geographic Information System (QGIS), another free and downloadable software. QGIS is compatible with numerous software, including the Esri suite of ArcGIS software and database structure. The image data includes both high-spatial-resolution Sentinel-2 optical data and Sentinel-1 synthetic aperture radar (SAR). Both datasets are freely available via a public portal that is maintained by the European Space Agency. The image-processing instruction handbook covers all aspects of acquiring and processing satellite-image data and importing vector-data sources into SNAP. The GIS analysis handbook covers final creation of map products from the maps created in SNAP and creation of GIS procedures in QGIS that are needed to manage the rangeland resources for wildlife and pastoral grazing. Although focused on the Kenyan conservancies and their semiarid environment, the processing methods and procedures are applicable for similar environments and management, and to a large part, even for integrated mapping and GIS functionality of any managed landscape resource. The instruction handbooks are synchronized to MP4 training videos created with U.S. Geological Survey-licensed Camtasia 9 software. The workbook and MP4 video combinations are suitable for a single user or a workshop setting.

Open-File Report↗
USGS2021

Cape Romain partnership for coastal protection

This final report summarizes activities, outcomes, and lessons learned from a 3-year project titled “Climate Change Adaptation for Coastal National Wildlife Refuges” with the Cape Romain National Wildlife Refuge (NWR) and local partners in the surrounding South Carolina Lowcountry. The Lowcountry is classified as the 10-county area encompassing the coastal plain of South Carolina (this report specifically focuses on Berkeley, Charleston, and Georgetown Counties). The goals of this work, sponsored by the U.S. Geological Survey’s Southeast Climate Adaptation Science Center (SECASC), were to foster active engagement with stakeholders; to develop a comprehensive definition of adaptation problems faced by agencies, organizations, and individuals near the Cape Romain NWR that accounts for global change, local values, knowledge and perceptions; and to encourage social learning and building of effective networks and trust across South Carolina Lowcountry organizations and individuals. Although project scoping began at the scale of the Atlantic seaboard, by engaging with NWRs from Massachusetts to Florida, participating refuge personnel eventually selected the Cape Romain NWR to serve as a case study for testing our goals. The Cape Romain Partnership for Coastal Conservation was established to address global change impacts at a regional level and includes representation from Federal and State resource agencies, local conservation nongovernmental organizations, and organizations representing underserved community interests. Research topics, originating from discussions with Cape Romain Partnership for Coastal Conservation members, focused on quantifying key drivers of change including localized sea-level rise (SLR) predictions, estimates of coastal hurricane inundation as amplified by SLR, and urban growth trends and forecasts. These key drivers provided a foundation to engage stakeholders in planning exercises to begin a process of collective understanding and collaborative decision making. The goal of this process was to develop collective strategies of adaptation to enhance community and ecosystem resilience in the South Carolina Lowcountry. South Carolina’s Lowcountry is experiencing rapid environmental and social transformation because of SLR rates approaching twice the global average, chronic tidal flooding and catastrophic storm surges, erosion and loss of habitats that provide essential services to wildlife and humans, and increasing social polarization fueled by aggressive low-density urban growth and other forms of land conversion. To support characterizations of plausible future scenarios, we used available or, in some cases, developed new models to project future conditions of key environmental and social-economic drivers. Because of the imprecision of mean global SLR projections, the SECASC commissioned a climatological study to account for local conditions and multiple representative concentration pathways to project a tailored distribution of future sea levels. These projections were matched to SLR scenarios provided by existing models to anticipate the range of future coastal habitat changes in the South Carolina Lowcountry. SLR scenarios were also incorporated into existing storm-surge models, which do not account for alternate baseline sea levels, to project the local effects of future hurricanes. To evaluate the extent and effects of population growth and urban expansion, we relied on an existing urban-growth model to map the spatial distribution of land-conversion probabilities, the total area of which is predicted to increase twofold to threefold over the next 60 years. In addition to this simplified model, an econometric model is in development to account for nonlinear feedback dynamics in land value, land use, and ecosystem service production. Although not yet completed, the goals of this model are to produce more-detailed projections of growth dynamics and to allow predictions of development patterns resulting from alternate land-use planning policies and incentives. Collaborative planning for an uncertain future requires more than providing decision makers with information on future physical and ecological conditions; developing effective and consensual strategies must also integrate sociological values, multiple cultural perspectives, and an understanding of human behavior. To support broad stakeholder engagement in integrative approaches to adaptation planning, emphasis was placed on the importance of considering differences in how individuals perceive their environment and create meaning. Because cultural frameworks form the basis for perceptions and, ultimately, the behaviors of individuals and institutions, we describe a model of human behavior and how it can be used to understand the effect of cultural complexity and variation in perception on choices, behavioral change, and long-term maintenance of behaviors. We consider a model commonly used in the field of behavioral health that accommodates variation in human perception when describing stages of behavior and the dynamics of behavioral change. Tailoring communication and engagement activities to targeted stakeholders is likely to benefit from increased understanding of behavioral change processes. The complex nature of this problem limited the usefulness of a traditional decision-analytic approach, we explored alternative methods for engagement, collaborative learning and decision making. Recognizing that project partners and Lowcountry stakeholders may be at different stages of preparedness and interest level for modifying behavior as a function of global change, we facilitated a scenario-planning exercise to familiarize partners with this well-established approach for communicating the opportunities and threats arising under alternative, plausible futures. We developed narratives for four alternative South Carolina Lowcountry scenarios to be used in later strategic planning that focus on quantitative trends for three primary drivers with high impact and high uncertainty: manifestations of climate change, social-political shifts at a global level, and forces of local value and power structures. This scenario-planning exercise underscored the complex relation between the temporospatial scale of the production of ecological goods and services and the institutional scale at which they are managed. We then guided the partners through an assessment of the relevant strengths and weaknesses of the Cape Romain Partnership for Coastal Protection, using the threats and opportunities characterized by each scenario to understand how the partnership might respond when attempting to meet conservation and societal objectives. The partnership identified key strengths including partnership experience, outreach and technical capacities, a substantial conservation land base, and high social cohesion in the South Carolina Lowcountry. Limited communication expertise, institutional inertia, and insufficient staffing and funding were recognized as important weaknesses across the partnership. By examining and scoring combinations of internal strengths and weaknesses and external threats and opportunities, the partnership developed sets of prioritized strategies to consider in the context of a given scenario. Although we had insufficient time to examine all scenarios in detail, the intent was to identify a portfolio of strategic actions to address threats and opportunities represented in multiple plausible futures. Top-ranking strategies encompassed a range of actions that focused on strengthening the conservation community and communicating the benefits of nature (that is, ecosystem services) to leveraging partnerships to expand land protection. This report also details the methods and preliminary results of several models developed or applied in support of this project. Two parcel-selection algorithms were used to evaluate anticipated habitat changes and patterns of urban growth to guide decisions on optimal conservation reserve design to protect habitat communities. One approach used a widely available planning software (MARXAN) to maximize conservation benefits near the Cape Romain NWR, whereas the other approach was a novel application of economic theory to account for uncertainty in future conditions and for the risks of unanticipated habitat loss. This latter model applies modern portfolio theory to estimate the risk of investing in any portfolio of land parcels (that is, candidate “reserves”) under climate-change uncertainty by quantifying the variation and spatial correlation of conservation benefits derived from each portfolio. We expanded the range of actions beyond simply whether or not to invest in a set of land parcels, an approach commonly used in spatial conservation planning, to also include consideration of divestment from currently protected lands. Such refinements allow for better accounting of system dynamics and can evaluate the benefits of flexible conservation tools such as rolling easements. Model results were conditional on a decision maker’s risk tolerance but highlighted general strategies of land conservation to increase future habitat representation beyond what is expected under the current protected land base. We built models that may help inform coastal planning by estimating salinity dynamics and the performance of oyster reef restoration efforts to predict the combined effects of global change and management of freshwater flows on coastal habitats and the processes that contribute to their resilience. These models can support restoration decisions by evaluating the expected benefits of site locations for shoreline protection and fisheries production. Lastly, we developed a spatially explicit economic model that predicts feedback dynamics among land value, land-use change, and effects on ecosystem service provision to explore zoning policies and incentives on urban growth and ecosystem services. We summarize these efforts with insights and considerations for the Cape Romain Partnership for Coastal Protection to continue to engage stakeholders in effective adaptation planning. First, notions of place attachment (referred to as sense of place), and the role of culture in social discourse are increasingly being used to understand the complex interactions between society and the environment and how societies respond and adapt to climate change. Sense of place was a unifying theme whenever the future of the South Carolina Lowcountry was discussed. The contribution of the South Carolina Lowcountry’s environmental wealth, rich cultural heritage, and quality of life to sense of place has important implications for how adaptation planning might best be pursued. More community-based governance of the commons (in other words, natural and cultural resources held in common), in which broad stakeholder participation and power sharing are key elements, is considered important. This devolution of governance is characterized by polycentric institutions and self-organizing social networks that promote a local culture of knowledge sharing, problem solving, and learning. These so-called bridging organizations (or individuals) often provide the leadership necessary to bring together potentially disparate Government agencies and institutions, private organizations, and individuals in a collective process of problem solving. Our observations also suggest that the conservation community in the South Carolina Lowcountry views its activities as integral to the broader governance of social-ecological systems, in which responses to the forces of global change are mediated through culture, economics, and politics. Rather than directly competing with other interests, the South Carolina Lowcountry conservation community seems to embrace an interpretation of conservation in which the fundamental objective is the quality of human life rather than environmental protection. Fundamental to the types of governance reforms described above is the notion of coproduction, in which experts and users collaborate to develop a shared body of knowledge. In this approach, scientists work with stakeholders to help frame questions, design research, and collect and analyze data. Such sustained collaborations are increasingly believed to be an effective way to produce useable (or actionable) science. The emphasis on social learning, leveraging strong social networks, coordinating and deliberating among diverse stakeholders, and applying principles of adaptive management is an essential contribution to adaptive capacity. The diverse and robust set of scientific approaches, methods to help stakeholders collaborate in effective and goal-driven planning processes, and decision tools resulting from this project hopefully will assist Cape Romain NWR and its partners prepare for climatic, ecological, and social changes over the coming decades.

South Carolina↗
USGS2021

Reconnaissance study of the major and trace element content of bauxite deposits in the Arkansas bauxite region, Saline and Pulaski Counties, central Arkansas

The Arkansas bauxite district, which comprises about 275 square miles (710 square kilometers) of central Arkansas, produced an order of magnitude more bauxite and alumina than the other bauxite districts in the United States combined. Bauxite was mined in the region continuously from 1898 to 1982. These bauxites are laterite deposits, formed from intensive in-place weathering of the exposed surface of the Granite Mountain pluton, a Late Cretaceous batholith composed mainly of nepheline syenite and lesser amounts of syenite. Nepheline syenite was the aluminum source for the bauxite and clay deposits that blanket the pluton. The early Eocene continental sedimentary rocks that contain and overlie the bauxite deposits indicate that central Arkansas had a warm tropical environment during bauxite formation. Bauxite ores are the principal sources of aluminum. Some of the global bauxite deposits have been found to contain co-occurring metals that have essential applications in modern technologies. For example, bauxite is the largest global source of gallium (Ga), used in semiconductors, which is recovered as a byproduct of processing bauxite to recover alumina. Other critical metal commodities within some bauxites that reportedly have potential for byproduct recovery include niobium (Nb), scandium (Sc), and rare earth elements (REEs). Currently (2021), the United States is wholly dependent on imports for its supplies of bauxite for processing to produce alumina. The United States is also dependent on foreign sources of gallium, niobium, and scandium, as well for most of its domestic requirements of REEs. For these reasons, samples were collected from Arkansas bauxite deposits, associated clays, mill residue wastes (respectively referred to as red muds and black sands), and the parent nepheline syenite to determine their elemental content, with a particular focus on gallium, niobium, scandium, and REEs. Each sample was analyzed for 60 elements; these data and the methods used are published as a U.S. Geological Survey data release. The results indicate that, of the critical metals in bauxites, gallium is a potential byproduct from the central Arkansas bauxite deposits. The highest gallium concentrations occur in the raw bauxite ore, with an average concentration of 76 parts per million (ppm). Gallium partitions with alumina (the product) rather than into mine waste residues. Results indicate an average niobium content of 662 ppm in the Arkansas bauxite ores. Niobium progressively increases in concentration from parent syenite (247 ppm) to clays (315 ppm) and further from bauxite (662 ppm) to processed residues (1,075 ppm). Low concentrations of scandium were found in all samples, averaging 10 ppm or less in the parent rock (syenite), bauxite, clays, and processing residues. Modest concentrations of the light and heavy REEs were found in samples of bauxite ores, bauxitic clays and interbedded clays, syenite, and the residues of ore. The highest REE values were found in processed residues, with average concentrations of 613 ppm total light REEs and 130 ppm total heavy REEs. These concentrations suggest that additional processing to recover REEs is unlikely to be economic in the foreseeable future.

Arkansas↗
USGS1979

Outer Continental Shelf oil and gas information program; Pacific index

The Outer Continental Shelf Lands Act of 1953, as amended in 1978, (43 U.S.C. 1331 et seq.), grants to the Secretary of the Interior the authority to issue leases for minerals on the U.S. Outer Continental Shelf (OCS). It provides the authority and guidelines which the Secretary utilizes for expeditious exploration and development of the OCS while ensuring timely access to information by affected states and local governments in order that appropriate planning will anticipate and ameliorate impacts from such OCS activities. This document is prepared in accordance with Part 30 of the Code of Federal Regulations (CFR), Section 252.5 and 43 CFR, Section 3300.2, which require that the Directors of the U.S. Geological Survey and the Bureau of Land Management shall make available an Index, listing all relevant, actual or proposed programs, plans, reports, environmental impact statements and other lease sale information, on a regular basis, to each affected state and, upon request, to the executive of any local government whose jurisdiction covers an area affected by OCS activities. Accordingly, the Geological Survey and the Bureau of Land Management are cooperating in a joint effort to compile all relevant information on the OCS Oil and Gas Leasing Program in an Index with four volumes; Alaska, Atlantic, Gulf of Mexico and Pacific. This volume is a listing of documents used in the Pacific Area OCS decisionmaking process, and the sequence of information presented parallels this process. The bibliographic references are presented by lease sale number, in the sequence in which the documents are generated in the Federal OCS leasing program. Thus, the reader may compare all documents of one type in the Pacific Area or trace a single lease sale throughout the entire leasing process. Activities which generate information throughout the OCS lease sale process are described under Other Documentation and Supplemental Reading. Other Documentation pertains to Federal data gathering and analysis programs which are an integral part of the OCS decisionmaking process and are used throughout the process due to the usefulness of their subject matter. The Supplemental Reading documents (Appendix A) are not used in decisionmaking but are invaluable sources of general OCS information.

California, Oregon, Washington↗
USGS1980

Petroleum-resource appraisal and discovery rate forecasting in partially explored regions

PART A: A model of the discovery process can be used to predict the size distribution of future petroleum discoveries in partially explored basins. The parameters of the model are estimated directly from the historical drilling record, rather than being determined by assumptions or analogies. The model is based on the concept of the area of influence of a drill hole, which states that the area of a basin exhausted by a drill hole varies with the size and shape of targets in the basin and with the density of previously drilled wells. It also uses the concept of discovery efficiency, which measures the rate of discovery within several classes of deposit size. The model was tested using 25 years of historical exploration data (1949-74) from the Denver basin. From the trend in the discovery rate (the number of discoveries per unit area exhausted), the discovery efficiencies in each class of deposit size were estimated. Using pre-1956 discovery and drilling data, the model accurately predicted the size distribution of discoveries for the 1956-74 period. PART B: A stochastic model of the discovery process has been developed to predict, using past drilling and discovery data, the distribution of future petroleum deposits in partially explored basins, and the basic mathematical properties of the model have been established. The model has two exogenous parameters, the efficiency of exploration and the effective basin size. The first parameter is the ratio of the probability that an actual exploratory well will make a discovery to the probability that a randomly sited well will make a discovery. The second parameter, the effective basin size, is the area of that part of the basin in which drillers are willing to site wells. Methods for estimating these parameters from locations of past wells and from the sizes and locations of past discoveries were derived, and the properties of estimators of the parameters were studied by simulation. PART C: This study examines the temporal properties and determinants of petroleum exploration for firms operating in the Denver basin. Expectations associated with the favorability of a specific area are modeled by using distributed lag proxy variables (of previous discoveries) and predictions from a discovery process model. In the second part of the study, a discovery process model is linked with a behavioral well-drilling model in order to predict the supply of new reserves. Results of the study indicate that the positive effects of new discoveries on drilling increase for several periods and then diminish to zero within 2? years after the deposit discovery date. Tests of alternative specifications of the argument of the distributed lag function using alternative minimum size classes of deposits produced little change in the model's explanatory power. This result suggests that, once an exploration play is underway, favorable operator expectations are sustained by the quantity of oil found per time period rather than by the discovery of specific size deposits. When predictions of the value of undiscovered deposits (generated from a discovery process model) were substituted for the expectations variable in models used to explain exploration effort, operator behavior was found to be consistent with these predictions. This result suggests that operators, on the average, were efficiently using information contained in the discovery history of the basin in carrying out their exploration plans. Comparison of the two approaches to modeling unobservable operator expectations indicates that the two models produced very similar results. The integration of the behavioral well-drilling model and discovery process model to predict the additions to reserves per unit time was successful only when the quarterly predictions were aggregated to annual values. The accuracy of the aggregated predictions was also found to be reasonably robust to errors in predictions from the behavioral well-drilling equation.

Professional Paper↗
USGS2007

Hydrogeology, Ground-Water-Age Dating, Water Quality, and Vulnerability of Ground Water to Contamination in a Part of the Whitewater Valley Aquifer System near Richmond, Indiana, 2002-2003

Assessments of the vulnerability to contamination of ground-water sources used by public-water systems, as mandated by the Federal Safe Drinking Water Act Amendments of 1996, commonly have involved qualitative evaluations based on existing information on the geologic and hydrologic setting. The U.S. Geological Survey National Water-Quality Assessment Program has identified ground-water-age dating; detailed water-quality analyses of nitrate, pesticides, trace elements, and wastewater-related organic compounds; and assessed natural processes that affect those constituents as potential, unique improvements to existing methods of qualitative vulnerability assessment. To evaluate the improvement from use of these methods, in 2002 and 2003, the U.S. Geological Survey, in cooperation with the City of Richmond, Indiana, compiled and interpreted hydrogeologic data and chemical analyses of water samples from seven wells in a part of the Whitewater Valley aquifer system in a former glacial valley near Richmond. This study investigated the application of ground-water-age dating, dissolved-gas analyses, and detailed water-quality analyses to quantitatively evaluate the vulnerability of ground water to contamination and to identify processes that affect the vulnerability to specific contaminants in an area of post-1972 greenfield development. The aquifer system in the study area includes an unconfined sand and gravel aquifer used for public-water supply (upper aquifer) and a confined sand and gravel aquifer (lower aquifer) separated by a till confining unit. Several hydrogeologic and cultural measures indicate that the upper aquifer is qualitatively vulnerable to contamination: the upper aquifer is unconfined and has a shallow depth to the water table (from about 4.75 to 14 feet below land surface), low-permeability sediments in the unsaturated zone are thin (less than 10 feet thick), estimated ground-water-flow rates through the upper aquifer are relatively rapid (the highest estimated rates ranged from 0.44 to about 5.0 feet per day), and potential contaminant sources were present. Ground-water-age dates indicate that ground-water samples represented recharge from about the time greenfield development began south of the ground-water-flow divide and that changes in water quality would lag changes in contaminant inputs. Estimates of ground-water age, computed with dichlorodifluoromethane (CFC-12) and trichlorotrifluoroethane (CFC-113) concentrations in water samples collected from seven observation wells in February and March 2003, indicated that water in the upper aquifer had recharged within about 13 to 30 years before sampling. Ground-water ages were youngest (from about 13 to 15 years since recharge) in water from the shallow wells along the glacial-valley margin and oldest (30 years) in water from a well at the base of the aquifer in the valley center. Ground-water ages determined for the shallow wells may be affected by mixing of recent recharge with older ground water from deeper in the aquifer, as indicated by upward hydraulic gradients between paired shallow and deep wells in the upper aquifer. Other parts of the Whitewater Valley aquifer system with similar hydrogeologic characteristics could be expected to have similarly young ground-water ages and residence times. Analyses of water samples collected from the seven observation wells in August and September 2002 indicated that concentrations of chloride, sodium, and nitrate generally were larger in ground water from the upper aquifer than in other parts of the Whitewater Valley aquifer system. Drinking-water-quality standards for Indiana were exceeded in water samples from one well for chloride concentrations, from four wells for dissolved-solids concentrations, and from one well for nitrate concentrations. Application of low-level methods for trace-element analyses determined that concentrations of aluminum, cobalt, iron, lithium, molybdenum, nickel, selenium, uranium, vanadium, and zinc were less than or equal to 8 micrograms per liter; concentrations of arsenic, cadmium, chromium, and copper were less than or equal to 1 microgram per liter. Application of low-level analytical methods to water samples enabled the detection of several pesticides and volatile, semivolatile, and wastewater-related organic compounds; concentrations of individual pesticides and volatile organic compounds were less than 0.1 microgram per liter and concentrations of individual wastewater organic compounds were less than 0.5 microgram per liter. The low-level analytical methods will provide useful data with which to compare future changes in water quality. Results of detailed water-quality analyses, ground-waterage dating, and dissolved-gas analyses indicated the vulnerability of ground water to specific types of contamination, the sequence of contaminant introduction to the aquifer relative to greenfield development, and processes that may mitigate the contamination. Concentrations of chloride and sodium and chloride/bromide weight ratios in sampled water from five wells indicated the vulnerability of the upper aquifer to roaddeicer contamination. Ground-water-age estimates from these wells indicated the onset of upgradient road-deicer use within the previous 25 years. Nitrate in the upper aquifer predates the post-1972 development, based on a ground-water-age date (30 years) and the nitrate concentration (5.12 milligrams per liter as nitrogen) in water from a deep well. Vulnerability of the aquifer to nitrate contamination is limited partially by denitrification. Detection of one to four atrazine transformation products in water samples from the upper aquifer indicated biological and hydrochemical processes that may limit the vulnerability of the ground water to atrazine contamination. Microbial processes also may limit the aquifer vulnerability to small inputs of halogenated aliphatic compounds, as indicated by microbial transformations of trichlorofluoromethane and trichlorotrifluoroethane relative to dichlorodifluoromethane. The vulnerability of ground water to contamination in other parts of the aquifer system also may be mitigated by hydrodynamic dispersion and biologically mediated transformations of nitrate, pesticides, and some organic compounds. Identification of the sequence of contamination and processes affecting the vulnerability of ground water to contamination would have been unlikely with conventional assessment methods.

Indiana, Ohio↗
USGS2013

Assessing total nitrogen in surface-water samples--precision and bias of analytical and computational methods

The characterization of total-nitrogen (TN) concentrations is an important component of many surface-water-quality programs. However, three widely used methods for the determination of total nitrogen—(1) derived from the alkaline-persulfate digestion of whole-water samples (TN-A); (2) calculated as the sum of total Kjeldahl nitrogen and dissolved nitrate plus nitrite (TN-K); and (3) calculated as the sum of dissolved nitrogen and particulate nitrogen (TN-C)—all include inherent limitations. A digestion process is intended to convert multiple species of nitrogen that are present in the sample into one measureable species, but this process may introduce bias. TN-A results can be negatively biased in the presence of suspended sediment, and TN-K data can be positively biased in the presence of elevated nitrate because some nitrate is reduced to ammonia and is therefore counted twice in the computation of total nitrogen. Furthermore, TN-C may not be subject to bias but is comparatively imprecise. In this study, the effects of suspended-sediment and nitrate concentrations on the performance of these TN methods were assessed using synthetic samples developed in a laboratory as well as a series of stream samples. A 2007 laboratory experiment measured TN-A and TN-K in nutrient-fortified solutions that had been mixed with varying amounts of sediment-reference materials. This experiment identified a connection between suspended sediment and negative bias in TN-A and detected positive bias in TN-K in the presence of elevated nitrate. A 2009–10 synoptic-field study used samples from 77 stream-sampling sites to confirm that these biases were present in the field samples and evaluated the precision and bias of TN methods. The precision of TN-C and TN-K depended on the precision and relative amounts of the TN-component species used in their respective TN computations. Particulate nitrogen had an average variability (as determined by the relative standard deviation) of 13 percent. However, because particulate nitrogen constituted only 14 percent, on average, of TN-C, the precision of the TN-C method approached that of the method for dissolved nitrogen (2.3 percent). On the other hand, total Kjeldahl nitrogen (having a variability of 7.6 percent) constituted an average of 40 percent of TN-K, suggesting that the reduced precision of the Kjeldahl digestion may affect precision of the TN-K estimates. For most samples, the precision of TN computed as TN-C would be better (lower variability) than the precision of TN-K. In general, TN-A precision (having a variability of 2.1 percent) was superior to TN-C and TN-K methods. The laboratory experiment indicated that negative bias in TN-A was present across the entire range of sediment concentration and increased as sediment concentration increased. This suggested that reagent limitation was not the predominant cause of observed bias in TN-A. Furthermore, analyses of particulate nitrogen present in digest residues provided an almost complete accounting for the nitrogen that was underestimated by alkaline-persulfate digestion. This experiment established that, for the reference materials at least, negative bias in TN-A was caused primarily by the sequestration of some particulate nitrogen that was refractory to the digestion process. TN-K biases varied between positive and negative values in the laboratory experiment. Positive bias in TN-K is likely the result of the unintended reduction of a small and variable amount of nitrate to ammonia during the Kjeldahl digestion process. Negative TN-K bias may be the result of the sequestration of a portion of particulate nitrogen during the digestion process. Negative bias in TN-A was present across the entire range of suspended-sediment concentration (1 to 14,700 milligrams per liter [mg/L]) in the synoptic-field study, with relative bias being nearly as great at sediment concentrations below 10 mg/L (median of -3.5 percent) as that observed at sediment concentrations up to 750 mg/L (median of -4.4 percent). This lent support to the laboratory-experiment finding that some particulate nitrogen is sequestered during the digestion process, and demonstrated that negative TN-A bias was present in samples with very low suspended-sediment concentrations. At sediment concentrations above 750 mg/L, the negative TN-A bias became more likely and larger (median of -13.2 percent), suggesting a secondary mechanism of bias, such as reagent limitation. From a geospatial perspective, trends in TN-A bias were not explained by selected basin characteristics. Though variable, TN-K bias generally was positive in the synoptic-field study (median of 3.1 percent), probably as a result of the reduction of nitrate. Three alternative approaches for assessing TN in surface water were evaluated for their impacts on existing and future sampling programs. Replacing TN-A with TN-C would remove the bias from subsequent data, but this approach also would introduce discontinuity in historical records. Replacing TN-K with TN-C would lead to the removal of positive bias in TN-K in the presence of elevated nitrate. However, in addition to the issues that may arise from a discontinuity in the data record, this approach may not be applicable to regulatory programs that require the use of total Kjeldahl nitrogen for stream assessment. By adding TN-C to existing TN-A or TN-K analyses, historical-data continuity would be preserved and the transitional period could be used to minimize the impact of bias on data analyses. This approach, however, imposes the greatest burdens on field operations and in terms of analytical costs. The variation in these impacts on different sampling programs will challenge U.S. Geological Survey scientists attempting to establish uniform standards for TN sample collection and analytical determinations.

Scientific Investigations Report↗
USGS1983

Uncertainties in records of annual mean discharge in Maine

This report documents the results of rating analyses of flow during periods of ice-cover at 33 stations on selected rivers in Maine. Results were obtained through linear multiple regression. It also presents functions relating uncertainties in records to the number of discharge measurements made at these and 21 other stations. The application is unusual in that it includes analysis of the uncertainty of discharge as affected by backwater from ice. Total uncertainty consists of errors incurred during measurement and during data processing. An average of 46.8 percent of the total variance for the 21 stations not affected by backwater was due to measurement variance, and 53.2 percent was due to process variance. Data from the remaining 33 stations were divided into summer (open-water) periods and the winter (backwater) periods. An average of 49.3 percent of the total variance for the summer-period stations was due to measurements variance; 50.7 percent was due to process variance. An average of 25.2 percent of the total variance for the winter-period stations was due to measurement variance; 74.8 percent was due to process variance. Results of the seasonal division of average variance suggest that the process and measurement variances are essentially equal during open-water periods and that process variance is considerably greater than the measurement variance during backwater periods. The errors in winter discharge records significantly increased average uncertainty in the records of annual mean discharge. (USGS)

Water-Resources Investigations Report↗
USGS1956

Water requirements of the carbon-black industry

Carbon blacks include an important group of industrial carbons used chiefly as a reinforcing agent in rubber tires. In 1953 more than 1,610 million pounds of carbon black was produced, of which approximately 1,134 million pounds was consumed by the rubber industry. The carbon-black industry uses small quantities of water as compared to some industries; however, the water requirements of the industry are important because of the dependence of the rubber-tire industry on carbon black. Two methods are used in the manufacture of carbon black - contact and furnace. The only process use of water in the contact method is that used in pelleting. Water is used also in the plant washhouse and for cleaning, and sometimes the company camp may be supplied by the plant. A survey made during the last quarter of 1953 showed that the average values of unit water use at contact plants for process use, all plant uses, and all uses including company camps are 0.08, 0.14, and 0.98 gallon of water per pound of carbon black respectively. In addition to use in wet pelleting, large quantities of water are required in continuous and cyclic furnace methods to reduce the temperature of the gases of decomposition in order to separate and collect the entrained carbon black. The 22 furnace plants in operation in 1953 used a total of 12.4 million gallons per day for process use. Four furnace plants generate electric power for plant use; condenser-cooling water for one such plant may nearly equal the requirements of the entire industry for process use. The average values of unit water use at furnace plants for process use, all plant uses and all uses including company camps but excluding power generation are 3.26, 3.34, and 3.45 gallons of water per pound of carbon black respectively. Carbon-black plants in remote, sparsely settled areas often must maintain company camps for employees. Twenty-one of twenty-seven contact plants surveyed in 1953 had company camps. These camps used large quantities of water: 0.84 gallon per pound of carbon black as compared to 0.14 gallon per pound used in the plants. Furnace plants can generally be located near a labor supply and, therefore, do not require company camps. Ten of the twenty-two furnace plants surveyed in 1953 had company camps. Because water used for pelleting and gas quenching is evaporated, leaving the dissolved minerals in the product as objectionable impurities, particular attention was paid to the quality of water available for use at the plants visited during the 1953 survey. Reports of chemical analyses of water samples were obtained at 23 plants. A study of these reports does not develop a pattern of the limits of tolerance of dissolved solids in water used in process or of the need for water treatment based on geographical location of the plant. However these analyses show that water used for quenching contains less dissolved solids than water used by the industry for any other purpose. Based on trends in the industry it is expected that the quantity of water used by the carbon-black industry will increase more rapidly than will the quantity of carbon black produced because of the increasing percentage produced in furnace plants, and that selection of sites for modern furnace plants will be influenced more by quantity and quality of the available water supply than was the case in selecting sites for contact plants for which low-cost natural gas was the primary consideration.

Water Supply Paper↗
USGS1956

Water requirements of the aluminum industry

Aluminum is unique among metals in the way it is obtained from its ore. The first step is to produce alumina, a white powder that bears no resemblance to the bauxite from which it is derived or to the metallic aluminum to which it is reduced by electrolytic action in a second step. Each step requires a complete plant facility, and the plants may be adjacent or separated by as much as the width of the North American continent. Field investigations sf every alumina plant and reduction works in the United States were undertaken to determine the industry's water use. Detailed studies were made of process and plant layout so that a water balance could be made for each plant to determine not only the gross water intake but also an approximation of the consumptive use of water. Water requirements of alumina plants range from 0.28 to 1.10 gallons per pound of alumina; the average for the industry is 0.66 gallon. Water requirements of reduction works vary considerably more, ranging from 1.24 to 36.33 gallons per pound of aluminum, and average 14.62 gallons. All alumina plants in the United States derive alumina from bauxite by the Bayer process or by the Combination process, a modification of the Bayer process. Although the chemical process for obtaining alumina from bauxite is essentially the same at all plants, different procedures are employed to cool the sodium aluminate solution before it enters the precipitating tanks and to concentrate it by evaporation of some of the water in the solution. Where this evaporation takes place in a cooling tower, water in the solution is lost to the atmosphere as water vapor and so is used consumptively. In other plants, the quantity of solution in the system is controlled by evaporation in a multiple-effect evaporator where practically all vapor distilled out of the solution is condensed to water that may be reused. The latter method is used in all recently constructed alumina plants, and some older plants are replacing cooling towers with multiple-effect evaporators. All reduction works in the United States use the Hall process, but the variation in water requirements is even greater than the variation at alumina plants, and, further, the total daily water requirement for all reduction works is more than 9 times the total daily requirement of all alumina plants. Many reduction works use gas scrubbers, but some do not. As gas scrubbing is one of the principal water uses in reduction works, the manner in which wash water is used, cooled, and reused accounts in large measure for the variation in water requirements. Although the supply of water for all plants but one was reported by the management to be ample for all plant needs, the economic factor of the cost of water differs considerably among plants. It is this factor that accounts in large measure for the widely divergent slant practices. Plant capacity alone has so little effect on plant water requirements that other conditions such as plant operation based on the cost of water, plant location, and the need for conservation of water mask any economy inherent in plant size.

Water Supply Paper↗
USGS2006

Adaptive harvest management of North American waterfowl populations - recent successes and future prospects

The history of North American waterfowl harvest management has been characterized by attempts to use population monitoring data to make informed harvest management decisions. Early attempts can be characterized as intuitive decision processes, and later efforts were guided increasingly by population models and associated predictions. In 1995, a formal adaptive management process was implemented, and annual decisions about duck harvest regulations in the United States are still based on this process. This formal decision process is designed to deal appropriately with the various forms of uncertainty that characterize management decisions, environmental uncertainty, structural uncertainty, partial controllability and partial observability. The key components of the process are (1) objectives, (2) potential management actions, (3) model(s) of population response to management actions, (4) credibility measures for these models, and (5) a monitoring program. The operation of this iterative process is described, and a brief history of a decade of its use is presented. Future challenges range from social and political issues such as appropriate objectives and management actions, to technical issues such as multispecies management, geographic allocation of harvest, and incorporation of actions that include habitat acquisition and management.

Book chapter↗
USGS2004

Abundance estimation and conservation biology

Abundance is the state variable of interest in most population–level ecological research and in most programs involving management and conservation of animal populations. Abundance is the single parameter of interest in capture–recapture models for closed populations (e.g., Darroch, 1958; Otis et al., 1978; Chao, 2001). The initial capture–recapture models developed for partially (Darroch, 1959) and completely (Jolly, 1965; Seber, 1965) open populations represented efforts to relax the restrictive assumption of population closure for the purpose of estimating abundance. Subsequent emphases in capture–recapture work were on survival rate estimation in the 1970’s and 1980’s (e.g., Burnham et al., 1987; Lebreton et al.,1992), and on movement estimation in the 1990’s (Brownie et al., 1993; Schwarz et al., 1993). However, from the mid–1990’s until the present time, capture–recapture investigators have expressed a renewed interest in abundance and related parameters (Pradel, 1996; Schwarz & Arnason, 1996; Schwarz, 2001). The focus of this session was abundance, and presentations covered topics ranging from estimation of abundance and rate of change in abundance, to inferences about the demographic processes underlying changes in abundance, to occupancy as a surrogate of abundance. The plenary paper by Link & Barker (2004) is provocative and very interesting, and it contains a number of important messages and suggestions. Link & Barker (2004) emphasize that the increasing complexity of capture–recapture models has resulted in large numbers of parameters and that a challenge to ecologists is to extract ecological signals from this complexity. They offer hierarchical models as a natural approach to inference in which traditional parameters are viewed as realizations of stochastic processes. These processes are governed by hyperparameters, and the inferential approach focuses on these hyperparameters. Link & Barker (2004) also suggest that our attention should be focused on relationships between demographic processes such as survival and recruitment, the two quantities responsible for changes in abundance, rather than simply on the magnitudes of these quantities. They describe a type of Jolly–Seber capture–recapture model that permits inference about the underlying relationship between per capita recruitment rates and survival rates (Link & Barker, this volume). Implementation used Bayesian Markov Chain Monte Carlo methods and appeared to work well, yielding inferences about the relationship between recruitment and survival that were robust to selection of prior distribution. We believe that readers will find their arguments compelling, and we expect to see increased use of hierarchical modeling approaches in capture–recapture and related fields. Otto (presentation without paper) also recommended use of hierarchical models in analysis of multiple data sources dealing with population dynamics of North American mallards. He integrated survival inferences from ringing data, abundance information from aerial survey data, and recruitment information based on age ratios from a harvest survey. He used a Leslie matrix population projection model as an integrating framework and obtained estimates of breeding population size using all data.Otto’s approach also permitted inference about biases in estimated quantities. As with the work of Link & Barker (2004), we find Otto’s recommendation to use hierarchical models to integrate data from multiple sources to be very compelling. Alisauskas et al. (2004) report results of an analysis of capture–recapture data for a askatchewan population of white–winged scoters. They used the approach of Pradel (1996) to estimate population growth rate (See the PDF) directly. Estimates for 1975–1985 were quite low, but estimates for the recent period, 2000–2003,increased to values > 1. Parameter estimates for seniority, survival and per capita recruitment (Pradel, 1996) led to the inference that increased recruitment was largely responsible for the improvements in population status and growth. However, various data sources also indicated that this increase in recruitment was likely a result of increased immigration rather than improved reproduction on the area. This latter inference is important from a conservation perspective in indicating the importance of birds in other locations to growth and health of the study population. Lukacs and Burnham presented material to be published elsewhere that dealt with the use of genetic markers in capture–recapture studies. The data sources for such studies are samples of hair or feces, which are then analyzed using molecular genetic techniques in order to determine individual genotypes with respect to a usually small number of loci. Two types of classification error can arise in such analyses. First, if only a small number of loci is examined, then there may be nonnegligible probabilities that multiple individual animals will have the same genotypes. The second type of error arises during the polymerase chain reaction (PCR) process and can result from failure of alleles to amplify (allelic dropout) or from PCR inhibitors in hair and feces that produce the appearance of false alleles or misprinting (Creel et al., 2003). Lukacs and Burnham developed models that formally incorporate possible misclassification of samples resulting from these errors. These models permit estimation of parameters such as abundance and survival in a manner that properly incorporates this uncertainty of individual identity. We anticipate that noninvasive sampling based on molecular genetic analyses of hair or feces will become extremely important for some species, and that the models of Lukacs and Burnham will become very popular for such analyses. MacKenzie & Nichols (2004) discuss the use of occupancy (proportion of patches or habitat area that is occupied) as a surrogate for abundance. In cases of territorial species and where birds occur at low densities, the number of occupied patches may provide a reasonable estimate of abundance. In other cases, occupancy can be viewed as providing information about one tail of the abundance distribution, P (N = 0). The motivation for considering occupancy as a surrogate for abundance is that occupancy is based on so–called presence–absence surveys that are frequently less expensive of time and effort than methods that estimate abundance directly. We describe one set of models that can be used to estimate occupancy for a single season and another that can be used to estimate parameters such as local probabilities of extinction and colonization that are associated with occupancy dynamics. We outline a possible hybrid approach that combines occupancy data with data on marked individuals in order to betterexplore the mechanisms underlying occupancy dynamics. These five presentations made for an interesting session containing useful information and recommendations for future work. A number of themes connecting these presentations could be emphasized. For example, two of the presentations considered alternatives to standard capture–recapture sampling that can be used to draw inferences about abundance, or a portion of the abundance distribution, with field methods that should be less expensive than usual capture–recapture approaches of handling animals. We believe that the most important theme of the session was the emphasis on the processes responsible for changes in abundance. In particular, we are excited by the potential for using hierarchical models as a means of investigating relationships among vital rates and as a means of combining multiple sources of data relevant to system dynamics. Indeed, we expect the importance of this session theme to be reflected in the content and presentations of the next EURING meeting.

Animal Biodiversity and Conservation↗
USGS2010

Methylmercury cycling, bioaccumulation, and export from agricultural and non-agricultural wetlands in the Yolo Bypass

This 18-month field study addresses the seasonal and spatial patterns and processes controlling methylmercury (MeHg) production, bioaccumulation, and export from natural and agricultural wetlands of the Yolo Bypass Wildlife Area (YBWA). The data were collected in conjuntion with a Proposition 40 grant from the State Water Resources Control Board in support of the development of Best Management Practices (BMP's) for reducing MeHg loading from agricultural lands in the wetland-dominated Yolo Bypass to the Sacramento-San Joaquin River Delta. The four managemenr-based questions addressed in this study were: 1. Is there a different among agricultural and managfed wetland types in terms of Me Hg dynamic (production, degradation, bioaccumulation, or export)? 2. Does water residence time influence MeHg dynamics? 3. Does the application of sulfate-based fertilizer impact MeHg production rates? 4. Does the presence (or absence) of vegetation influence MeHg production rates? Measurements of MeHg concentrations in sediment, water, and biota (plants, invertebrates, and fish) were made to assess management-level patterns in five wetland types, which included three type of shallowly-flooded agricultural wetlands (white rice, wild rice, and fallow) and two types of managed wetlands (permanently and seasonally flooded). To strengthen our understanding of the processes underlying the seasonal and spatial patterns of MeHg cycling, additional exploratory factors were measured including ancillary sediment and water quality parameters, stable isotope fractionation (oxygen, sulfur, carbon, and nitrogen), photodemethylation rates, and daily-integrated hydrologic budgets. Samples and field data were collected from May 2007 to July 2008, and nearly all sample analyses were completed by September 2008 as per the Quality Assurance Program Plan (QAPP) requirements. Although wetland type was a major factor that drove the study design, within-field hydrology also proved to be an important factor controlling aqueous MeHg and total mercury (THg) concentrations and export. Overall, agricultural wetlands exhibited higher MeHg concentrations in overlying water, sediment, and biota than did managed seasonal and permanent wetlands. This appears to be partly due to higher rates of sediment in microbial production of MeHg on agricultural wetlands during the fall through spring period. Both sulfate- and iron-reducing bacteria have been implicated in the MeHg production process, and both were demonstrably active in all wetlands studied; however, sulfate-reducing bacteria were not stimulated by the addition of sulfate-based fertilizer to agricultural wetlands, suggesting that easily-degraded (labile) organic matter, rather than sulfate, was limiting their activity in these field types. The data suggest that agriculturally-managed soils promoted MeHg production through 1) enhanced microbial activity via higher temperatures and larger pools of labile carbon, and 2) enhanced pools of microbially available inorganic divalent mercury (Hg(II)) resulting from a decrease in reduced-sulfur, solid-phase minerals under oxic or only mildly reducing conditions. MeHg mass balances were assessed by comparing filed-specific MeHg loads for inlets vs. outlet flows. The overall mass balance for MeHg in surface water during the summer irrigation period (June - September 2007) indicated little to no net MeHg export from the six agricultural wetlands taken as a whole. Of the six agricultural wetlands, there was net overall MeHg export from two fields (one fallow and one white rice) during August, and from four of the six fields (one fallow, one white rice, and two wild rice) during September) Over the entire summer irrigation period, two of the fields (one fallow and one wild rive) showed net MeHg export, and the other four fields showed wither net import or no significant change. Rates of measured photomethylation and exchange between sediment and water pools suggest that both processes may be responsible for the lack of MeHg export. Despite significant differences during winter months between fields in surface water concentrations of MeHg, MeHg loads were not calculated in mid-winter because flood waters had overtopped field boundaries and field fidelity could not be established. During the summer 2007 irrigation season, surface water out-flows from agricultural wetlands were 9%-36% of inlet flows, and evaporation rates explained most of this water loss, with infiltration likely accounting for the remainder. Unfiltered aqueous MeHg concentrations increased from <1 ng L -1 in source waters to up to 10 ng L -1 in agricultural wetland drains during the summer irrigation period. Increases in solute concentration caused by evapoconcentration were estimated by determining concentration factors (outflow/inflow) for chloride (a conservative dissolved constituent) and by measuring oxygen isotope ratios ( 18 O/ 16 O, expressed as δ 18 O) in water. Increases in MeHg concentration from inflows-to-outflows exceeded those caused by evapoconcentration on several fields during the summer irrigation season. This was especially true when initial surface water MeHg concentrations were low, as seen in the southern block of fields receiving irrigation water directly from the Toe Drain. The northern block of fields received irrigation water from Greens Lake, which included Toe Drain water plus recirculated drain water from other agricultural fields within the Yolo Bypass and west of the Yolo Bypass; as such, the northern fields showed a smaller percentage increase in MeHg concentration because initial MeHg concentrations in surface water inflows were greater than in inputs to the southern fields. Mercury concentrations in fish were greater in agricultural wetlands white rice and wild rice) than in the two permanently flooded wetlands. Additionally, Hg concentrations in biota showed a general increase from inlets to outlets withing agricultural wetlands, but not within permanent wetlands. This was particular evident in white rice fields where caged western mosquitofish at the outlets had Hg concentrations that were more than 4 times higher than in caged fish held at the inlets. Similar spatial patterns in Hg bioaccumulation in agricultural and permanent wetlands were seen for wild populations of western mosquitofish and Mississippi silversides. In contrast to fish, invertebrates, such as water-boatman (Corixidae) and back swimmers (Notonectidae), had greater Hg concentrations in permanent wetlands than in tempoarirly flooded agricultural wetlands, Fish THg concentrations were weakly correlated with water MeHg,a and not correlated with sediment MeHg. In contrast, invertebrate MeHg concentrations were more strongly correlated with sediment MeHg than with water MeHg concentrations. These results illustrate the complexity of MeHg bioaccumulation through food webs and indicate the importance of simultaneously using multiple biosentinels when monitoring MeHg production and bioaccumulation. Despite high sediment production rates and water concentrations in agricultural wetlands, MeHg export was physically limited by hydrologic export for all wetlands studied. We suggest that load reduction is maximized by limiting water throughout, but that on-site biota exposure is maximized by this loner water residence time. While field-specific hydrologic loads could not be fully quantified during flood conditions in February 2008, we suggest that the primary period of MeHg export from Yolo Bypass Wildlife Area is during those winter flooding periods when overall microbial activity and MeHg production in agricultural soils is fueled by the decomposition of rice straw, and when hydrologic flowthrough is maximal. Local stakeholders participated in two workshops related to this study, demonstrating an interest in understanding factors controlling MeHg production, export, and bioaccumulation. The results of this field study show that permanently flooded, naturally vegetated wetlands are unlikely to a large source of MeHg production within the YBWA, in contrast with agriculturally-managed wetlands. MeHg loading to Toe Drain waters of the Yolo Bypass may be reduced by lowering rated of hydrologic export from agricultural wetlands during the growing season and especially during rice harvest, However, under these water-holding conditions, biota living within agricultural wetlands may thus be exposed to higher MeHg concentrations in surface water, As observed in this study, rapid bioacculumaltion over a 2-month period led to MeHg concentrations in invertebrates and fish more than 6 and 11 times higher, respectively, than proposed TMDL target values to protect wildlife (0.03 ppm ww). The results of this field study, together with the information from YBWA stakeholders, provide a more definitive understanding of how MeHg cycling and bioaccumulation respond to habitat differences and specific management practices. These results directly address 4 core components of CBDA's Mercury Strategy for the Bay-Delta Ecosystem (Wiener et al., 2003a): a) Quantification and evaluation of THg and MeHg sources, b) Quantification of effects of ecosystem restoration on MeHg exposure, c) Assessment of ecological risk, and d) Identification and testing of potential management approaches for reducing MeHg contamination. In addition, the quantitative results reported here assess the effect of current land use practices in the Yolo Bypass MeHg production, bioaccumulation and export, and provide process-based advice towards achieving current goals of the RWQCB-CVR's Sacramento -- San Joaquin Delta Estuary TMDL for Methyl & Total Mercury (Wood et al., 2010b). Further work is necessary to evaluate biotic exposure in the Yolo Bypass Wildlife Area at higher trophic levels (e.g. birds), to quantify winter hydrologic flux of MeHg to the larger Delta ecosystem, and to evaluate rice straw management options to limit labile carbon supplies to surface sediment during winter months. In summary, agricultural management of rice fields -- specifically the periodic flooding and production of easily degraded organic matter -- promotes the production of MeHg beyond rates seen in naturally vegetated wetlands, whether seasonally or permanently flooded., The exported load from MeHg from these agricultural wetlands may be controlled by limiting hydrologic export from fields to enhance on-site MeHg removal processes, but the tradeoff is that this impoundement increases Me Hg exposure to resident organisms.

California↗
USGS1996

Manufacture of ammonium sulfate fertilizer from gypsum-rich byproduct of flue gas desulfurization - A prefeasibility cost estimate

Costs for constructing and operating a conceptual plant based on a proposed process that converts flue gas desulfurization (FGD)-gypsum to ammonium sulfate fertilizer has been calculated and used to estimate a market price for the product. The average market price of granular ammonium sulfate ($138/ton) exceeds the rough estimated cost of ammonium sulfate from the proposed process ($111/ ton), by 25 percent, if granular size ammonium sulfate crystals of 1.2 to 3.3 millimeters in diameters can be produced by the proposed process. However, there was at least ??30% margin in the cost estimate calculations. The additional costs for compaction, if needed to create granules of the required size, would make the process uneconomical unless considerable efficiency gains are achieved to balance the additional costs. This study suggests the need both to refine the crystallization process and to find potential markets for the calcium carbonate produced by the process.

ACS Division of Fuel Chemistry, Preprints↗
USGS1999

Protocol and practice in the adaptive management of waterfowl harvests

Waterfowl harvest management in North America, for all its success, historically has had several shortcomings, including a lack of well-defined objectives, a failure to account for uncertain management outcomes, and inefficient use of harvest regulations to understand the effects of management. To address these and other concerns, the U.S. Fish and Wildlife Service began implementation of adaptive harvest management in 1995. Harvest policies are now developed using a Markov decision process in which there is an explicit accounting for uncontrolled environmental variation, partial controllability of harvest, and structural uncertainty in waterfowl population dynamics. Current policies are passively adaptive, in the sense that any reduction in structural uncertainty is an unplanned by-product of the regulatory process. A generalization of the Markov decision process permits the calculation of optimal actively adaptive policies, but it is not yet clear how state-specific harvest actions differ between passive and active approaches. The Markov decision process also provides managers the ability to explore optimal levels of aggregation or "management scale" for regulating harvests in a system that exhibits high temporal, spatial, and organizational variability. Progress in institutionalizing adaptive harvest management has been remarkable, but some managers still perceive the process as a panacea, while failing to appreciate the challenges presented by this more explicit and methodical approach to harvest regulation. Technical hurdles include the need to develop better linkages between population processes and the dynamics of landscapes, and to model the dynamics of structural uncertainty in a more comprehensive fashion. From an institutional perspective, agreement on how to value and allocate harvests continues to be elusive, and there is some evidence that waterfowl managers have overestimated the importance of achievement-oriented factors in setting hunting regulations. Indeed, it is these unresolved value judgements, and the lack of an effective structure for organizing debate, that present the greatest threat to adaptive harvest management as a viable means for coping with management uncertainty. Copyright ?? 1999 by The Resilience Alliance.

Conservation Ecology↗
USGS2015

Automated extraction of natural drainage density patterns for the conterminous United States through high performance computing

Hydrographic networks form an important data foundation for cartographic base mapping and for hydrologic analysis. Drainage density patterns for these networks can be derived to characterize local landscape, bedrock and climate conditions, and further inform hydrologic and geomorphological analysis by indicating areas where too few headwater channels have been extracted. But natural drainage density patterns are not consistently available in existing hydrographic data for the United States because compilation and capture criteria historically varied, along with climate, during the period of data collection over the various terrain types throughout the country. This paper demonstrates an automated workflow that is being tested in a high-performance computing environment by the U.S. Geological Survey (USGS) to map natural drainage density patterns at the 1:24,000-scale (24K) for the conterminous United States. Hydrographic network drainage patterns may be extracted from elevation data to guide corrections for existing hydrographic network data. The paper describes three stages in this workflow including data pre-processing, natural channel extraction, and generation of drainage density patterns from extracted channels. The workflow is concurrently implemented by executing procedures on multiple subbasin watersheds within the U.S. National Hydrography Dataset (NHD). Pre-processing defines parameters that are needed for the extraction process. Extraction proceeds in standard fashion: filling sinks, developing flow direction and weighted flow accumulation rasters. Drainage channels with assigned Strahler stream order are extracted within a subbasin and simplified. Drainage density patterns are then estimated with 100-meter resolution and subsequently smoothed with a low-pass filter. The extraction process is found to be of better quality in higher slope terrains. Concurrent processing through the high performance computing environment is shown to facilitate and refine the choice of drainage density extraction parameters and more readily improve extraction procedures than conventional processing.

Conference Paper↗
USGS2014

Two approaches for incorporating climate change into natural resource management planning at Wind Cave National Park

Wind Cave National Park (WICA) protects one of the world’s longest caves, has large amounts of high quality, native vegetation, and hosts a genetically important bison herd. The park’s relatively small size and unique purpose within its landscape requires hands-on management of these and other natural resources, all of which are interconnected. Anthropogenic climate change presents an added challenge to WICA natural resource management because it is characterized by large uncertainties, many of which are beyond the control of park and National Park Service (NPS) staff. When uncertainty is high and control of this uncertainty low, scenario planning is an appropriate tool for determining future actions. In 2009, members of the NPS obtained formal training in the use of scenario planning in order to evaluate it as a tool for incorporating climate change into NPS natural resource management planning. WICA served as one of two case studies used in this training exercise. Although participants in the training exercise agreed that the scenario planning process showed promise for its intended purpose, they were concerned that the process lacked the scientific rigor necessary to defend the management implications derived from it in the face of public scrutiny. This report addresses this concern and others by (1) providing a thorough description of the process of the 2009 scenario planning exercise, as well as its results and management implications for WICA; (2) presenting the results of a follow-up, scientific study that quantitatively simulated responses of WICA’s hydrological and ecological systems to specific climate projections; (3) placing these climate projections and the general climate scenarios used in the scenario planning exercise in the broader context of available climate projections; and (4) comparing the natural resource management implications derived from the two approaches. Wind Cave National Park (WICA) protects one of the world’s longest caves, has large amounts of high quality, native vegetation, and hosts a genetically important bison herd. The park’s relatively small size and unique purpose within its landscape requires hands-on management of these and other natural resources, all of which are interconnected. Anthropogenic climate change presents an added challenge to WICA natural resource management because it is characterized by large uncertainties, many of which are beyond the control of park and National Park Service (NPS) staff. When uncertainty is high and control of this uncertainty low, scenario planning is an appropriate tool for determining future actions. In 2009, members of the NPS obtained formal training in the use of scenario planning in order to evaluate it as a tool for incorporating climate change into NPS natural resource management planning. WICA served as one of two case studies used in this training exercise. Although participants in the training exercise agreed that the scenario planning process showed promise for its intended purpose, they were concerned that the process lacked the scientific rigor necessary to defend the management implications derived from it in the face of public scrutiny. This report addresses this concern and others by (1) providing a thorough description of the process of the 2009 scenario planning exercise, as well as its results and management implications for WICA; (2) presenting the results of a follow-up, scientific study that quantitatively simulated responses of WICA’s hydrological and ecological systems to specific climate projections; (3) placing these climate projections and the general climate scenarios used in the scenario planning exercise in the broader context of available climate projections; and (4) comparing the natural resource management implications derived from the two approaches.

Report↗