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At least 253 records · Page 14Linked to original sources
USGS2016

The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management

The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the United States Department of Agriculture’s Agricultural Research Service and Natural Resources Conservation Service, and the United States Department of the Interior’s Bureau of Land Management, to address the need for a long-term research program to meet critical challenges in wind erosion research and management in the United States. The Network has three aims: (1) provide data to support understanding of basic aeolian processes across land use types, land cover types, and management practices, (2) support development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and (3) encourage collaboration among the aeolian research community and resource managers for the transfer of wind erosion technologies. The Network currently consists of thirteen intensively instrumented sites providing measurements of aeolian sediment transport rates, meteorological conditions, and soil and vegetation properties that influence wind erosion. Network sites are located across rangelands, croplands, and deserts of the western US. In support of Network activities, http://winderosionnetwork.org was developed as a portal for information about the Network, providing site descriptions, measurement protocols, and data visualization tools to facilitate collaboration with scientists and managers interested in the Network and accessing Network products. The Network provides a mechanism for engaging national and international partners in a wind erosion research program that addresses the need for improved understanding and prediction of aeolian processes across complex and diverse land use types and management practices.

Arizona, California, Colorado, Idaho, North Dakota↗
USGS2024

An introduction to Criteria for Reporting and Evaluating Exposure Datasets (CREED) for use in environmental assessments

Risks posed by environmental exposure to chemicals are routinely assessed to inform activities ranging from environmental status reporting to authorization and registration of chemicals for commercial uses. Environmental risk assessment generally relies on two key values generated from exposure data and ecotoxicity data. Data sets of measured concentrations of chemicals in environmental matrices, referred to here as exposure data, are widely used to support environmental risk management, decision-making, and reporting, such as for chemical screening, ecological or human health risk assessments, and establishment of guidelines. Practitioners have developed schemes to determine the suitability of ecotoxicity data for specific purposes, focused on evaluating reliability and relevance, but analogous schemes are not available for exposure data. Moreover, regulatory guidance arguably provides less resolution on reporting and evaluating exposure data sets compared to ecotoxicity data. The evaluation of exposure data sets is subject to limitations from variable or unreported data quality objectives and/or from differences in expert judgments, potentially introducing bias and leading to decisions based on flawed and/or inconsistent information. Exposure data sets should be evaluated for reliability and relevance prior to use in environmental assessments. This paper is the first of a four-paper series detailing the outcomes of a Society of Environmental Toxicology and Chemistry technical workshop that has developed Criteria for Reporting and Evaluating Exposure Datasets (CREED). The workshop participants developed practical, systematic criteria for consistent and transparent evaluation of the reliability (quality) and relevance (fitness for purpose) of exposure data. This guidance should apply to many different (unspecified) purposes of assessment. CREED can be used to evaluate existing data sets, but can also inform data generators interested in improving their data collection and reporting to maximize data utility to other users. This first paper details existing frameworks for the evaluation of exposure data sets and demonstrates the need for CREED, drawing from different regulatory assessments, and describes the technical workshop.

Integrated Environmental Assessment and Management↗
USGS2010

Agronomic and environmental implications of enhanced s-triazine degradation

Novel catabolic pathways enabling rapid detoxification of s -triazine herbicides have been elucidated and detected at a growing number of locations. The genes responsible for s -triazine mineralization, i.e. atzABCDEF and trzNDF , occur in at least four bacterial phyla and are implicated in the development of enhanced degradation in agricultural soils from all continents except Antarctica. Enhanced degradation occurs in at least nine crops and six crop rotation systems that rely on s -triazine herbicides for weed control, and, with the exception of acidic soil conditions and s -triazine application frequency, adaptation of the microbial population is independent of soil physiochemical properties and cultural management practices. From an agronomic perspective, residual weed control could be reduced tenfold in s -triazine-adapted relative to non-adapted soils. From an environmental standpoint, the off-site loss of total s -triazine residues could be overestimated 13-fold in adapted soils if altered persistence estimates and metabolic pathways are not reflected in fate and transport models. Empirical models requiring soil pH and s -triazine use history as input parameters predict atrazine persistence more accurately than historical estimates, thereby allowing practitioners to adjust weed control strategies and model input values when warranted.

Pest Management Science↗
USGS2020

From forests to fish: Mercury in mountain lake food webs influenced by factors at multiple scales

Mountain lakes, while seemingly pristine, have been subjected to historical fish stocking practices and exposure to atmospherically deposited contaminants like mercury. Mercury bioaccumulation in these ecosystems varies widely due to strong environmental gradients, and there are complex, hierarchical factors that affect mercury transport and loading, methylmercury production, and food web biomagnification. We sought to assess how representative variables associated with watershed, lake, and food web‐scale processes—specifically, catchment tree cover, lake benthic primary production, and fish diet, respectively—are associated with mercury concentrations in mountain lake fish. Mean fish mercury concentrations varied threefold between lakes, with nearshore tree cover and fish diet accounting for the most variance in fish mercury. Tree cover was likely positively correlated to fish Hg due to its contributions to local deposition and its effect on lake biogeochemistry. Fish with benthic diets tended to have higher mercury concentrations, illustrating that food web processes are an important consideration when investigating drivers of contaminant bioaccumulation. Our results suggest that both landscape and ecological factors are determinants of fish mercury bioaccumulation, and thus variables at multiple scales should be considered when managing mountain lake food webs for mercury exposure risk.

Washington↗
USGS2019

Risk at the margins: A natural hazards perspective on the Syrian refugee crisis in Lebanon

Quantitative landslide risk analysis is a key step in creating appropriate land use policies. The forced migration of those displaced by recent armed conflict in Syria has highlighted the need for studies to guide humanitarian aid and resettlement policies. Over 1.5 million displaced Syrians now reside in Lebanon, self-settling throughout the country through urban integration and informal encampment due to Lebanon's prohibition of formal refugee camps. The Syrian-Lebanon refugee crisis coincides with the recent reexamination of the established aid practice of camp-based resettlement, focused on issues of aid efficacy, security, and human dignity but lacking an environmental hazards perspective. In light of these issues, we quantitatively assess the landslide risk profile of Lebanon, finding a 75% increase in landslide risk since the start of the Syrian crisis. The risk is highest in the debris flow-prone mountains of central and northeastern Lebanon. Additionally, Syrian refugees settled in informal camps experience 9–11 times greater risk then urban populations due to sub-standard shelter, suggesting that urban rather than camp-based resettlement policies are preferable from an environmental-hazards perspective.

International Journal of Disaster Risk Reduction↗
USGS2021

Ten simple rules for creating a scientific web application

The use of scientific web applications (SWApps) across biological and environmental sciences has grown exponentially over the past decade or so. Although quantitative evidence for such increased use in practice is scant, collectively, we have observed that these tools become more commonplace in teaching, outreach, and in science coproduction (e.g., as decision support tools). Despite the increased popularity of SWApps, researchers often receive little or no training in creating such tools. Although rolling out SWApps can be a relatively simple and quick process using modern, popular platforms like R shiny apps or Tableau dashboards, making them useful, usable, and sustainable is not. These 10 simple rules for creating a SWApp provide a foundation upon which researchers with little to no experience in web application design and development can consider, plan, and carry out SWApp projects.

PLOS Computational Biology↗
USGS2024

Prefabricated Zero Ascend Omnispecies (ZAO) modular fish passage modules using advanced manufacturing techniques

The Zero Ascend Omnispecies (ZAO) fish passage attraction module “ZAO Attractor” is a novel system designed to facilitate upstream passage for a broad spectrum of fish species, with a particular focus on American shad and river herring (alewife and/or blueback herring). Combining the use of prefabricated, modular components with advanced manufacturing, the ZAO aims to provide a cost-effective and scalable solution for fish passage attractions across various hydropower sites. The system features a surface level entry, so fish do not need to climb. In addition, it is designed to be adjusted and repositioned to create the most effective attraction flows by managing the outflows from hydropower turbines. Budget Period 1 (BP1) focused on the design and modeling of the ZAO Attractor and demonstrated the engineering feasibility of a modular, prefabricated, hydrodynamically efficient structure with surface level entry and passage. During BP1, the hypothesis was that certain structural adaptations, such as the addition of long fins, could direct turbine outflows to create a desirable downstream flow. Simulations, however, were inconclusive, revealing the complex nature of fish preferences for hydraulic conditions. It was discovered that there were limited published studies on the direct correlation between quantified flow patterns and fish attraction, emphasizing the need for controlled studies to observe and measure these effects. In Budget Period 2 (BP2), controlled studies with live fish were prioritized to address these complexities. A partially scaled ZAO Attractor was evaluated in laboratory conditions using native river water to assess its capability to attract and guide fish. Despite challenges with flume flow conditions and the impact of flume dimensions on flow directionality and velocity, the studies provided insights into fish behavior and preferences, particularly the requirement for a consistent flow stream for migration cues. Adjustments to the fin structure demonstrated potential effectiveness in guiding fish toward the module. However, the hydraulic conditions within the flume environment did not accurately reflect typical in-river scenarios, therefore the results were inconclusive with respect to the optimal system configuration for in-river use. In the future, conducting comprehensive field studies can enhance understanding of the interactions between fish behavior and flow conditions created by the ZAO Attractor. Additionally, a design review is advised, particularly regarding the load scenarios throughout the seasons and positioning of the ZAO Attractor. These studies should continue to refine the design to achieve its intended benefits: economical and effective fish attraction and passage that can be adapted to specific site conditions while allowing for continued energy generation at sites up for re-licensure and adding hydropower generation to previously untapped resources in non-powered dams and new stream reaches. In conclusion, the ZAO fish passage attraction module presents a promising approach to fish passage at hydropower stations, with the potential to balance environmental concerns with renewable energy development. However, further field validation and optimization are necessary to ensure its effectiveness and practicality in real-world applications.

Final Technical Report↗
USGS1996

Nutrients in the Nation's Waters--Too Much of a Good Thing?

Historical data on nutrients (nitrogen and phosphorus) from about 12,000 ground-water and more than 22,000 stream samples have been compiled and related to possible sources. This existing information was collected by many agencies for a variety of purposes. Therefore, though it can be used to determine where concentrations differ, the exact percentages should not be taken as those for the Nation as a whole. Major findings include: (1) nutrient concentrations in water generally are related to land use in the area overlying ground-water aquifers or upstream from surface-water locations, (2) regional differences are related to differences in soil-drainage properties and agricultural practices, (3) nitrate concentrations in about 12 percent of domestic-supply wells in agricultural areas exceeded the U.S. Environmental Protection Agency's drinking-water standard (10 mg/L), and (4) nitrate concentrations in surface water rarely exceed the drinking-water standard. This information has helped identify locations across the Nation where ground water and streams are most likely to be vulnerable to nutrient contamination. Programs to manage and protect water resources can therefore be targeted to the most critical areas, providing the greatest protection for the least cost.

Circular↗
USGS2015

Results of mineral, chemical, and sulfate isotopic analyses of water, soil, rocks, and soil extracts from the Pariette Draw Watershed, Uinta Basin, Utah

In 2010, Utah Department of Environmental Quality (DEQ) Division of Water Quality (UDWQ, 2010) determined that water quality in Pariette Draw was in violation of Federal and State water quality criteria for total dissolved solids (TDS), selenium (Se), and boron (B). The measure of total dissolved solids is the sum of all the major ion concentrations in solution and in this case, the dominant ions are sodium (Na) and sulfate (SO4), which can form salts like thenardite (Na2SO4) and mirabilite (Na2SO4⋅H2O). The Utah Department of Environmental Quality (2010) classified the contamination as natural background and from nonpoint sources related to regional lithology and irrigation practices. Although the daily loads of the constituents of concern and water chemistry have been characterized for parts of the watershed, little is known about the controls that bedrock and soil mineralogy have on salt, Se, and B storage and the water-rock interactions that influence the mobility of these components in ground and surface waters. Studies in the Uncompahgre River watershed in Colorado by Tuttle and others (2014a, 2014b) show that salt derived from weathering of shale in a semiarid climate is stored in a variety of minerals that contribute solutes to runoff and surface waters based on a complex set of conditions such as water availability, geomorphic position (for example, topography controls the depth of salt accumulation in soils), water-table fluctuations, redox conditions, mineral dissolution kinetics, ion-exchange reactions, and secondary mineral formation. Elements like Se and B commonly reside in soluble salt phases, so knowledge of the behavior of salt minerals also sheds light on the behavior of associated contaminants. The goal of this study was to establish a process-based understanding of salt, Se, and B behavior to address whether these contaminants can be better managed, or if uncontrollable natural processes will overwhelm any attempts to bring Pariette Draw into compliance with respect to recently established total maximum daily limits (TMDLs). We collected data to refine our knowledge about the role of rock weathering and soil formation in the transport and storage of salt in the watershed and to show how salt is cycled under irrigated and natural conditions. Our approach was to sample rock, soils, and sediment on irrigated and natural terrain for mineralogical analysis to determine the residence of salt and associated Se and B, classify minerals as primary (related to rock formation) or secondary weathering products, and characterize mineral dissolution kinetics. Mineral and chemical analyses and selective extractions of rocks and soils provide useful information in understanding solute movement and mineral dissolution/ formation. The resulting data are critical in determining residence of salt, Se, and B in weathered rock and soil and understanding the mobility during water-rock-soil interactions. This report summarizes our methods for sample and data collection and tabulates the mineral, chemical, and isotopic data collected.

Utah↗
USGS1976

Thermal effects on fish ecology

Of all the environmental factors that influence aquatic organisms, temperature is the most all-pervasive. There is always an environmental temperature while other factors may or may not be present to exert their effects. Fish are, for all practical purposes, thermal conformers, or obligate poikilotherms. That is, they are able to exert little significant influence on maintaining a certain body temperature by specialized metabolic or behavioral means. Their body temperature thus fluctuates nearly in concert with the temperature of their aquatic medium (although particularly large, actively-moving fish such as tuna have deep muscle temperatures slightly higher than the water). Intimate contact at the gills of body fluids with the outside water and the high specific heat of water provide a very efficient heat exchanger that insures this near identity of internal and external temperatures.

Book chapter↗
USGS2020

Assessing the state of water resource knowledge and tools for future planning in the lower Rio Grande-Rio Bravo Basin

The Rio Grande/Rio Bravo Basin (hereinafter referred to as the Rio Grande) is a transboundary basin, with the Rio Grande forming the border between the United States and Mexico for approximately 2,034 km. The waters of the Rio Grande serve as a critical drinking source for 13 million people, connecting numerous population centers representing diverse backgrounds and cultures along its length. Cross-border ecosystems and communities make water management strategies particularly challenging. With different regulations and societal interests in the two countries, developing effective water-management strategies is challenging and requires the coordination of diverse interested parties representing different government agencies, institutions, and stakeholder groups with varying and sometimes conflicting objectives. To better evaluate the human and environmental water needs (environmental flows) of this constrained river system, an improved understanding of past and present water management objectives, policies, allocation practices, and water use is needed.

Lower Rio Grande-Río Bravo Basin↗
USGS2024

Opportunities for improved consideration of cultural benefits in environmental decision-making

Many cultural benefits of ecosystem services (ES) are difficult to capture in standard ES assessments. Scholars and practitioners often respond to this gap by seeking to develop new scientific methods to capture and integrate the plural values associated with diverse cultural benefits categories. This increasing emphasis on value pluralism represents an essential step toward recognitional justice within ES theory and practice. However, current approaches continue to rest on the assumption that ES-knowledge is only made available to decision-makers through scientific documentation. As a result, scholars and decision-makers fail to account for the role of knowledge pluralism as a core element of recognitional justice, and a key enabling factor for meaningful consideration of the plural values linked to cultural benefits of ES. In this paper, we contribute to a pluralist theory of cultural-benefits-knowledge, and ES-knowledge more broadly. Using a critical interpretive synthesis of environmental management literature, we conceptualize a wider range of knowledge forms that convey cultural benefits, based on the knowledge-as-practice concept in addition to the knowledge-as-product concept more familiar to Western actors. As part of the synthesis, we explore when and how diverse forms of cultural-benefits-knowledge intersect with decision-making processes, and the value aspects and categories of cultural benefits most frequently conveyed by each form of knowledge. Our synthesizing argument offers a critique of the concept of “ES-knowledge-use,” proposing a shift in focus toward “learning opportunities” that exist across phases of decision-making. We demonstrate that attention to a greater diversity of knowledge forms (knowledge pluralism), and a fuller spectrum of opportunities to integrate them (learning opportunities) can support more meaningful consideration of the plural values associated with cultural benefits of ES (value pluralism). In combination, attention to knowledge pluralism and value pluralism can help bring the ES approach into alignment with environmental justice through the recognition and legitimization of multiple identities, well-beings, and human-nature relationships, as reflected in meaningful consideration of the diverse cultural benefits of ES.

Ecosystem Services↗
USGS1995

Hydrology and the effects of selected agricultural best-management practices in the Bald Eagle Creek watershed, York County, Pennsylvania, prior to and during nutrient management: Water-quality study for the Chesapeake Bay Program

The U.S. Geological Survey, in cooperation with the Susquehanna River Basin Commission and the Pennsylvania Department of Environmental Resources, conducted a study as part of the U.S. Environmental Protection Agency's Chesapeake Bay Program to determine the effects of nutrient management of surface-water quality by reducing animal units in a 0.43-square-mile agricultural watershed in York County. The study was conducted primarily from October 1985 through September 1990 prior to and during the implementation of nutrient-management practices designed to reduce nutrient and sediment discharges. Intermittent sampling continued until August 1991. The Bald Eagle Creek Basin is underlain by schist and quartzite. About 87 percent of the watershed is cropland and pasture. Nearly 33 percent of the cropland was planted in corn prior to nutrient management, whereas 22 percent of the cropland was planted in corn during the nutrient-management phase. The animal population was reduced by 49 percent during nutrient management. Average annual applications of nitrogen and phosphorus from manure to cropland were reduced by 3,940 pounds (39 percent) and 910 pounds (46 percent), respectively, during nutrient management. A total of 94,560 pounds of nitrogen (538 pounds per acre) and 26,400 pounds of phosphorus (150 pounds per acre) were applied to the cropland as commercial fertilizer and manure during the 5-year study. Core samples from the top 4 feet of soil were collected prior to and during nutrient management and analyzed from concentrations of nitrogen and phosphorus. The average amount of nitrate nitrogen in the soil ranged from 36 to 135 pounds per acre, and soluble phosphorus ranged from 0.39 to 2.5 pounds per acre, prior to nutrient management. During nutrient management, nitrate nitrogen in the soil ranged from 21 to 291 pounds per acre and soluble phosphorus ranged from 0.73 to 1.7 pounds per acre. Precipitation was about 18 percent below normal and streamflow was about 35 percent below normal prior to nutrient management, whereas precipitation was 4 percent above normal and streamflow was 3 percent below normal during the first 2 years of nutrient management. Eighty-four percent of the 20.44 inches of streamflow was base flow prior to nutrient management and 54 percent of the 31.14 inches of streamflow was base flow during the first 2 years of the nutrient-management phase. About 31 percent of the measured precipitation during the first 4 years of the study was discharged as surface water; the remaining 69 percent was removed as evapotranspiration or remained in ground-water storage. Median concentrations of total nitrogen and dissolved nitrate plus nitrite in base flow increased from 4.9 and 4.1 milligrams per liter as nitrogen, respectively, prior to nutrient management to 5.8 and 5.0 milligrams per liter, respectively, during nutrient management. Median concentrations of ammonia nitrogen and organic nitrogen did not change significantly in base flow. Median concentrations of total and dissolved phosphorus in base flow did not change significantly and were 0.05 and 0.03 milligrams per liter as phosphorus, respectively, prior to the management phase, and 0.05 and 0.04 milligrams per liter, respectively, during the management phase.

Pennsylvania↗
USGS2008

Digital atlas of the upper Washita River basin, southwestern Oklahoma

Numerous types of environmental data have been collected in the upper Washita River basin in southwestern Oklahoma. However, to date these data have not been compiled into a format that can be comprehensively queried for the purpose of evaluating the effects of various conservation practices implemented to reduce agricultural runoff and erosion in parts of the upper Washita River basin. This U.S. Geological Survey publication, 'Digital atlas of the upper Washita River basin, southwestern Oklahoma' was created to assist with environmental analysis. This atlas contains 30 spatial data sets that can be used in environmental assessment and decision making for the upper Washita River basin. This digital atlas includes U.S. Geological Survey sampling sites and associated water-quality, biological, water-level, and streamflow data collected from 1903 to 2005. The data were retrieved from the U.S. Geological Survey National Water Information System database on September 29, 2005. Data sets are from the Geology, Geography, and Water disciplines of the U.S. Geological Survey and cover parts of Beckham, Caddo, Canadian, Comanche, Custer, Dewey, Grady, Kiowa, and Washita Counties in southwestern Oklahoma. A bibliography of past reports from the U.S. Geological Survey and other State and Federal agencies from 1949 to 2004 is included in the atlas. Additionally, reports by Becker (2001), Martin (2002), Fairchild and others (2004), and Miller and Stanley (2005) are provided in electronic format.

Data Series↗
USGS2017

Landscape genetic approaches to guide native plant restoration in the Mojave Desert

Restoring dryland ecosystems is a global challenge due to synergistic drivers of disturbance coupled with unpredictable environmental conditions. Dryland plant species have evolved complex life-history strategies to cope with fluctuating resources and climatic extremes. Although rarely quantified, local adaptation is likely widespread among these species and potentially influences restoration outcomes. The common practice of reintroducing propagules to restore dryland ecosystems, often across large spatial scales, compels evaluation of adaptive divergence within these species. Such evaluations are critical to understanding the consequences of large-scale manipulation of gene flow and to predicting success of restoration efforts. However, genetic information for species of interest can be difficult and expensive to obtain through traditional common garden experiments. Recent advances in landscape genetics offer marker-based approaches for identifying environmental drivers of adaptive genetic variability in non-model species, but tools are still needed to link these approaches with practical aspects of ecological restoration. Here, we combine spatially-explicit landscape genetics models with flexible visualization tools to demonstrate how cost-effective evaluations of adaptive genetic divergence can facilitate implementation of different seed sourcing strategies in ecological restoration. We apply these methods to Amplified Fragment Length Polymorphism (AFLP) markers genotyped in two Mojave Desert shrub species of high restoration importance: the long-lived, wind-pollinated gymnosperm Ephedra nevadensis , and the short-lived, insect-pollinated angiosperm Sphaeralcea ambigua . Mean annual temperature was identified as an important driver of adaptive genetic divergence for both species. Ephedra showed stronger adaptive divergence with respect to precipitation variability, while temperature variability and precipitation averages explained a larger fraction of adaptive divergence in Sphaeralcea . We describe multivariate statistical approaches for interpolating spatial patterns of adaptive divergence while accounting for potential bias due to neutral genetic structure. Through a spatial bootstrapping procedure, we also visualize patterns in the magnitude of model uncertainty. Finally, we introduce an interactive, distance-based mapping approach that explicitly links marker-based models of adaptive divergence with local or admixture seed sourcing strategies, promoting effective native plant restoration.

Mojave Desert↗
USGS2011

Development of industrial minerals in Colorado

Technology and engineering have helped make mining safer and cleaner for both humans and the environment. Inevitably, mineral development entails costs as well as benefits. Developing a mine is an environmental, engineering, and planning challenge that must conform to many Federal, State, and local regulations. Community collaboration, creative design, and best management practices of sustainability and biodiversity can be positive indicators for the mining industry. A better understanding of aesthetics, culture, economics, geology, climate, vegetation and wildlife, topography, historical significance, and regional land planning is important in resolving land-use issues and managing mineral resources wisely. Ultimately, the consuming public makes choices about product use (including water, food, highways, housing, and thousands of other items) that influence operations of the mineral industry. Land planners, resource managers, earth scientists, designers, and public groups have a responsibility to consider sound scientific information, society's needs, and community appeals in making smart decisions concerning resource use and how complex landscapes should change. An effort to provide comprehensive geosciences data for land management agencies in central Colorado was undertaken in 2003 by scientists of the U.S. Geological Survey and the Colorado Geological Survey. This effort, the Central Colorado Assessment Project, addressed a variety of land-use issues: an understanding of the availability of industrial and metallic rocks and minerals, the geochemical and environmental effects of historic mining activity on surface water and groundwater, and the geologic controls on the availability and quality of groundwater. The USDA Forest Service and other land management agencies have the opportunity to contribute to the sustainable management of natural aggregate and other mineral resources through the identification and selective development of mineral resources and the reclamation of mines on lands that they administer. The information in this Circular will help them carry out that task.

Colorado↗
USGS2003

Bioreactors for removing methyl bromide following contained fumigations

Use of methyl bromide (MeBr) as a quarantine, commodity, or structural fumigant is under scrutiny because its release to the atmosphere contributes to the depletion of stratospheric ozone. A closed-system bioreactor consisting of 0.5 L of a growing culture of a previously described bacterium, strain IMB-1, removed MeBr (>110 μmol L -1 ) from recirculating air. Strain IMB-1 grew slowly to high cell densities in the bioreactor using MeBr as its sole carbon and energy source. Bacterial oxidation of MeBr produced CO 2 and hydrobromic acid (HBr), which required continuous neutralization with NaOH for the system to operate effectively. Strain IMB-1 was capable of sustained oxidation of large amounts of MeBr (170 mmol in 46 d). In an open-system bioreactor (10-L fermenter), strain IMB-1 oxidized a continuous supply of MeBr (220 μmol L -1 in air). Growth was continuous, and 0.5 mol of MeBr was removed from the air supply in 14 d. The specific rate of MeBr oxidation was 7 × 10 -16 mol cell -1 h -1 . Bioreactors such as these can therefore be used to remove large quantities of contaminant MeBr, which opens the possibility of biodegradation as a practical means for its disposal.

Environmental Science & Technology↗
USGS2002

Fish communities of the Sacramento River Basin: Implications for conservation of native fishes in the Central Valley, California

The associations of resident fish communities with environmental variables and stream condition were evaluated at representative sites within the Sacramento River Basin, California between 1996 and 1998 using multivariate ordination techniques and by calculating six fish community metrics. In addition, the results of the current study were compared with recent studies in the San Joaquin River drainage to provide a wider perspective of the condition of resident fish communities in the Central Valley of California as a whole. Within the Sacramento drainage, species distributions were correlated with elevational and substrate size gradients; however, the elevation of a sampling site was correlated with a suite of water-quality and habitat variables that are indicative of land use effects on physiochemical stream parameters. Four fish community metrics - percentage of native fish, percentage of intolerant fish, number of tolerant species, and percentage of fish with external anomalies - were responsive to environmental quality. Comparisons between the current study and recent studies in the San Joaquin River drainage suggested that differences in water-management practices may have significant effects on native species fish community structure. Additionally, the results of the current study suggest that index of biotic integrity-type indices can be developed for the Sacramento River Basin and possibly the entire Central Valley, California. The protection of native fish communities in the Central Valley and other arid environments continues to be a conflict between human needs for water resources and the requirements of aquatic ecosystems; preservation of these ecosystems will require innovative management strategies.

Environmental Biology of Fishes↗