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At least 1,783 records · Page 99Linked to original sources
USGS2000

Nitrite fixation by humic substances: Nitrogen-15 nuclear magnetic resonance evidence for potential intermediates in chemodenitrification

Studies have suggested that NO − 2 , produced during nitrification and denitrification, can become incorporated into soil organic matter and, in one of the processes associated with chemodenitrification, react with organic matter to form trace N gases, including N 2 O. To gain an understanding of the nitrosation chemistry on a molecular level, soil and aquatic humic substances were reacted with 15 N-labeled NaNO 2 , and analyzed by liquid phase 15 N and 13 C nuclear magnetic resonance (NMR). The International Humic Substances Society (IHSS) Pahokee peat and peat humic acid were also reacted with Na 15 NO 2 and analyzed by solid-state 15 N NMR. In Suwannee River, Armadale, and Laurentian fulvic acids, phenolic rings and activated methylene groups underwent nitrosation to form nitrosophenols (quinone monoximes) and ketoximes, respectively. The oximes underwent Beckmann rearrangements to 2° amides, and Beckmann fragmentations to nitriles. The nitriles in turn underwent hydrolysis to 1° amides. Peaks tentatively identified as imine, indophenol, or azoxybenzene nitrogens were clearly present in spectra of samples nitrosated at pH 6 but diminished at pH 3. The 15 N NMR spectrum of the peat humic acid exhibited peaks corresponding with N-nitroso groups in addition to nitrosophenols, ketoximes, and secondary Beckmann reaction products. Formation of N-nitroso groups was more significant in the whole peat compared with the peat humic acid. Carbon-13 NMR analyses also indicated the occurrence of nitrosative demethoxylation in peat and soil humic acids. Reaction of 15 N-NH 3 fixated fulvic acid with unlabeled NO − 2 resulted in nitrosative deamination of aminohydroquinone N, suggesting a previously unrecognized pathway for production of N 2 gas in soils fertilized with NH 3

Soil Science Society of America Journal↗
USGS2007

Origin of the Lyme Dome and implications for the timing of multiple Alleghanian deformational and intrusive events in southern Connecticut

Geologic mapping, structural analysis, and geochronology in the area of the Lyme dome, southern Connecticut provides constraints on the origin of the rocks in the core of the dome, the absolute timing of the principal deformational and thermal events attributed to Alleghanian orogenesis, and the processes that generated the dome. Detrital zircon geochronology in combination with ages on intrusive rocks brackets the deposition of quartzite in the core of the dome sometime between ca. 925 and 620 Ma. Granite and granodiorite intruded the Neoproteorozic metasedimentary rocks in the core of the dome at ca. 620 to 610 Ma. Four major early Permian events associated with the Alleghanian orogeny affected the rocks in the Lyme dome area. Syn-tectonic migmatization and widespread penetrative deformation (D1, ca. 300 - 290 Ma) included emplacement of alaskite at 290 ?? 4 Ma during regional foliation development and aluminosilicate-orthoclase metamorphic conditions. Rocks of the Avalon terrane may have wedged between Gander cover rocks and Gander basement in the core of the Lyme during D1. Limited structural evidence for diapiric uplift of the Lyme dome indicates that diapirism started late in D1 and was completed by D2 (ca. 290 - 280 Ma) when horizontal WNW contractional stresses dominated over vertical stresses. Second sillimanite metamorphism continued and syn-tectonic D2 granite pegmatite (288 ?? 4 Ma) and the Joshua Rock Granite Gniess (284 ?? 3 Ma) intruded at this time. North-northwest extension during D3 (ca. 280 - 275 Ma) led to granitic pegmatite intrusion along S3 cleavage planes and in extensional zones in boudin necks during hydraulic failure and decompression melting. Intrusion of a Westerly Granite dike at 275 ?? 4 Ma suggests that D3 extension was active, and perhaps concluding, by ca. 275 Ma. Late randomly oriented but gently dipping pegmatite dikes record a final stage of intrusion during D4 (ca. 275 - 260 Ma), and a switch from NNW extension to vertical unloading and exhumation. Monazite and metamorphic zircon rim ages record this event at ca. 259 Ma. The evolution of the Lyme dome involved D1 mylonitization, intrusion, and migmatization during north-directed contraction, limited late D1 diapirism, D2 migmatization during WNW contraction with associated flexural flow and fold interference, D3 NNW horizontal extension and decompression melting, and final D4 vertical extension and rapid exhumation. Late regional uplift, extension, and normal faulting at higher crustal levels may have been caused by diapiric rise of the lower crust, below the structural level of the Lyme dome. The rocks record no evidence of Acadian metamorphism or deformation, suggesting that the Gander zone here was not tectonically juxtaposed with Avalon until the Alleghanian orogeny.

American Journal of Science↗
USGS2011

Characterizing contaminant concentrations with depth by using the USGS well profiler in Oklahoma, 2003-9

Since 2003, the U.S. Geological Survey (USGS) Oklahoma Water Science Center has been using the USGS well profiler to characterize changes in water contribution and contaminant concentrations with depth in pumping public-supply wells in selected aquifers. The tools and methods associated with the well profiler, which were first developed by the USGS California Water Science Center, have been used to investigate common problems such as saline water intrusion in high-yield irrigation wells and metals contamination in high-yield public-supply wells. The USGS well profiler is a slim (less than 1 inch in diameter), high-pressure hose that can be raised and lowered between the production pipe and casing (or borehole) of a well by using a motorized hose reel. Use of this tool is considerably less expensive than use of standard methods of depth-dependent sampling, and the USGS well profiler generally requires less downtime of the well. In terms of data quality, the greatest advantage of the USGS well profiler is that all data collection is performed under production pumping rates. In Oklahoma, the USGS well profiler has been modified and adapted for use in low-yield (150?350 gallons per minute) wells of various construction types common in Oklahoma. This tool has been used in selected public-supply wells in Hinton, Moore, and Norman to identify which producing zones are contaminated by naturally occurring arsenic. The tool and method also can be used to investigate other nonvolatile contaminants of interest, including uranium, radium, barium, boron, lead, selenium, sulfate, chloride, fluoride, nitrate, and chromium. In 2007, the USGS well profiler was used to investigate saline water intrusion in a deep public-supply well completed in the Ozark (Roubidoux) aquifer. In northeast Oklahoma, where the Ozark aquifer is known to be susceptible to contamination from mining activities, the well profiler also could be used to investigate sources (depths) of metals contamination and to identify routes of entry of metals to production wells.Water suppliers can consider well rehabilitation as a potential remediation strategy because of the ability to identify changes in contaminant concentrations with depth in individual wells with the USGS well profiler. Well rehabilitation methods, which are relatively inexpensive compared to drilling and completing new wells, involve modifying the construction or operation of a well to enhance the production of water from zones with lesser concentrations of a contaminant or to limit the production of water from zones with greater concentrations of a contaminant. One of the most effective well rehabilitation methods is zonal isolation, in which water from contaminated zones is excluded from production through installation of cement plugs or packers. By using relatively simple and inexpensive well rehabilitation methods, water suppliers may be able to decrease exposure of customers to contaminants and avoid costly installation of additional wells, conveyance infrastructure, and treatment technologies.

Fact Sheet↗
USGS2012

Effects of watershed densities of animal feeding operations on nutrient concentrations and estrogenic activity in agricultural streams

Application of manures from animal feeding operations (AFOs) as fertilizer on agricultural land can introduce nutrients and hormones (e.g. estrogens) to streams. A landscape-scale study was conducted in the Shenandoah River watershed (Virginia, USA) in order to assess the relationship between densities of AFOs in watersheds of agricultural streams and in-stream nutrient concentrations and estrogenic activity. The effect of wastewater treatment plants (WWTPs) on nutrients and estrogenic activity was also evaluated. During periods of high and low flow, dissolved inorganic nitrogen (DIN) and orthophosphate (PO4-P) concentrations were analyzed and estrogens/estrogenic compounds were extracted and quantified as17β-estradiol equivalents (E2Eq) using a bioluminescent yeast estrogen screen. Estrogenic activity was measurable in the majority of collected samples, and 20% had E2Eq concentrations > 1 ng/L. Relatively high concentrations of DIN (> 1000 μg/L) were also frequently detected. During all sampling periods, there were strong relationships between watershed densities of AFOs and in-stream concentrations of DIN (R2 = 0.56–0.81) and E2Eq (R2 = 0.39–0.75). Relationships between watershed densities of AFOs and PO4-P were weaker, but were also significant (R2 = 0.27–0.57). When combined with the effect of watershed AFO density, streams receiving WWTP effluent had higher concentrations of PO4-P than streams without WWTP discharges, and PO4-P was the only analyte with a consistent relationship to WWTPs. The results of this study suggest that as the watershed density of AFOs increases, there is a proportional increase in the potential for nonpoint source pollution of agricultural streams and their receiving waters by nutrients, particularly DIN, and compounds that can cause endocrine disruption in aquatic organisms.

Science of the Total Environment↗
USGS1997

Episodic nature of earthquake activity in stable continental regions revealed by palaeoseismicity studies of Australian and North American Quaternary faults

Palaeoseismic investigations of recent faulting in stable continental regions of Australia, North America and India show that these faults typically have a long-term behaviour characterised by episodes of activity separated by quiescent intervals of at least 10 000 and commonly 100 000 years or more. Long recurrence intervals such as these are well documented by detailed studies of the faults that ruptured during the 1986 Marryat Creek, South Australia and 1988 Tennant Creek, Northern Territory earthquakes. Thus, neotectonic features associated with stable continental region faults such as scarps and grabens commonly have subtle geomorphic expression and may be poorly preserved. Many potentially hazardous faults in stable continental regions are aseismic, which is one reason why the inventory of these faults is incomplete. Although they may be currently aseismic, faults in stable continental regions that are favourably oriented for movement in the current stress field could produce damaging earthquakes, often in unexpected places. Comprehensive palaeoseismic investigations of modern and prehistoric faulting events in stable continental regions are needed to understand the long-term behaviour of these faults, and thereby, improve seismic-hazard assessments.

Australian Journal of Earth Sciences↗
USGS2014

Flood-inundation maps for the White River near Edwardsport, Indiana

Digital flood-inundation maps for a 3.3-mile reach of the White River near Edwardsport, (Ind.), were created by the U.S. Geological Survey (USGS) in cooperation with the Indiana Department of Transportation. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at USGS streamgage 03360730, White River near Edwardsport, Ind. Near-real-time stages at this streamgage may be obtained from the USGS National Water Information System at http://waterdata.usgs.gov/ or the National Weather Service Advanced Hydrologic Prediction Service at http://water.weather.gov/ahps/, which also forecasts flood hydrographs at this site (site EDWI3.) Flood profiles were computed for the White River near Edwardsport reach by means of a one-dimensional step-back-water model developed by the U.S. Army Corps of Engineers. The hydraulic model was calibrated by using the most current stage-discharge relations at USGS streamgage 03360730, White River near Edwardsport, Ind., and high-water marks from the flood of April 2013. The calibrated hydraulic model was then used to determine 19 water-surface profiles for flood stages at approximately 1-foot intervals referenced to the streamgage datum and ranging from bankfull to the highest stage of the current stage-discharge rating curve. The simulated water-surface profiles were then combined with a geographic information system digital elevation model to delineate the area flooded at each water level. The availability of these maps, along with Internet information regarding current stage from the USGS streamgage 03360730 White River near Edwardsport, Ind., and forecasted stream stages from the National Weather Service, provides emergency management personnel and residents with information that is critical for flood response activities such as evacuations and road closures, as well as for post-flood recovery efforts.

Indiana↗
USGS1999

A dynamic water-quality modeling framework for the Neuse River estuary, North Carolina

As a result of fish kills in the Neuse River estuary in 1995, nutrient reduction strategies were developed for point and nonpoint sources in the basin. However, because of the interannual variability in the natural system and the resulting complex hydrologic-nutrient inter- actions, it is difficult to detect through a short-term observational program the effects of management activities on Neuse River estuary water quality and aquatic health. A properly constructed water-quality model can be used to evaluate some of the potential effects of manage- ment actions on estuarine water quality. Such a model can be used to predict estuarine response to present and proposed nutrient strategies under the same set of meteorological and hydrologic conditions, thus removing the vagaries of weather and streamflow from the analysis. A two-dimensional, laterally averaged hydrodynamic and water-quality modeling framework was developed for the Neuse River estuary by using previously collected data. Development of the modeling framework consisted of (1) computational grid development, (2) assembly of data for model boundary conditions and model testing, (3) selection of initial values of model parameters, and (4) limited model testing. The model domain extends from Streets Ferry to Oriental, N.C., includes seven lateral embayments that have continual exchange with the main- stem of the estuary, three point-source discharges, and three tributary streams. Thirty-five computational segments represent the mainstem of the estuary, and the entire framework contains a total of 60 computa- tional segments. Each computational cell is 0.5 meter thick; segment lengths range from 500 meters to 7,125 meters. Data that were used to develop the modeling framework were collected during March through October 1991 and represent the most comprehensive data set available prior to 1997. Most of the data were collected by the North Carolina Division of Water Quality, the University of North Carolina Institute of Marine Sciences, and the U.S. Geological Survey. Limitations in the modeling framework were clearly identified. These limitations formed the basis for a set of suggestions to refine the Neuse River estuary water-quality model.

North Carolina↗
USGS2020

Differences in neonicotinoid and metabolite sorption to activated carbon are driven by alterations to the insecticidal pharmacophore

Widespread application of neonicotinoids has led to their proliferation in waters. Despite low neonicotinoid hydrophobicity, our prior studies implicated granular activated carbon (GAC) in neonicotinoid removal. Based on known receptor binding characteristics, we hypothesized that the insecticidal pharmacophore influences neonicotinoid sorption. Our objectives were to illuminate drivers of neonicotinoid sorption for parent neonicotinoids (imidacloprid, clothianidin, thiamethoxam, and thiacloprid) and pharmacophore-altered metabolites (desnitro-imidacloprid and imidacloprid urea) to GAC, powdered activated carbon, and carbon nanotubes (CNTs). Neonicotinoid sorption to GAC was extensive and largely irreversible, with significantly greater sorption of imidacloprid than desnitro-imidacloprid. Imidacloprid and imidacloprid urea (electronegative pharmacophores) sorbed most extensively to nonfunctionalized CNTs, whereas desnitro-imidacloprid (positive pharmacophore) sorbed most to COOH-CNTs, indicating the importance of charge interactions and/or hydrogen bonding between the pharmacophore and carbon surface. Water chemistry parameters (temperature, alkalinity, ionic strength, and humic acid) inhibited overall neonicotinoid sorption, suggesting that pharmacophore-driven sorption in real waters may be diminished. Analysis of a full-scale drinking water treatment plant GAC filter influent, effluent, and spent GAC attributes neonicotinoid/metabolite removal to GAC under real-world conditions for the first time. Our results demonstrate that the neonicotinoid pharmacophore not only confers insecticide selectivity but also impacts sorption behavior, leading to less effective removal of metabolites by GAC filters in water treatment.

Environmental Science and Technology↗
USGS2024

Subduction intraslab-interface fault interactions in the 2022 Mw 6.4 Ferndale, California earthquake sequence

The Mendocino triple junction, the intersection of the Pacific, North American, and Gorda plates, activates a collection of disparate faults that reconcile Cascadia subduction with San Andreas transform motion. The December 20, 2022, Mw 6.4 Ferndale, California earthquake occurred within this complex zone as strike-slip faulting within the subducting Gorda slab. Here, we analyze the seismic and geodetic signatures of the mainshock and aftershock sequence to illuminate its role within complex tectonic surroundings. We find aftershocks on varied fault structures within the uppermost Gorda slab, yet seismicity on the subduction interface itself was notably absent. Nevertheless, we identify small but coherent postseismic deformation that is well modeled by aseismic slip on this interface, likely triggered by stresses generated at the updip limit of coseismic rupture. This sequence demonstrates the potential for interactions between intra-slab earthquakes and slip on the subduction megathrust, highlighting the need to consider this and other subduction zones as coupled systems of interacting faults.

California↗
USGS2023

Editorial: Volcanic forecasting, crisis management, and risk communication

Volcanic eruptions intermittently punctuate periods of repose at volcanic centers and fields. Forecasting the timing, style, distribution, and magnitude of these eruptions is difficult, because eruptive activity varies over time, commonly in an irregular way. Furthermore, the impacts of eruptions can include loss of lives, property damage, and social and economic disturbance, where every eruption produces different impacts. Mitigation of volcanic risk is therefore complex, requiring community action that is aided by preparedness actions of emergency managers, stakeholders, community leaders, and individuals, and by timely delivery and reception of hazard information during a crisis. This Research Topic addresses efforts to understand complexities in these relations dealing with volcanic unrest, eruptions, and eruption impacts. Research Topic range from eruption forecasting (Wild et al.; Christophersen et al.; Bernard et al.) and volcanic hazard assessment (Mead et al.) to risk communication and action (Martinez-Villegas et al.; Todesco et al.; Graham et al.; Bernard et al.) prior to and during volcanic crises. The studies use various methodologies and approaches, touching on various parts of the integrated, multi-partner systems that exist to improve risk mitigation.

Frontiers in Earth Science↗
USGS2018

Exposure to human-associated chemical markers of fecal contamination and self-reported illness among swimmers at recreational beaches

Anthropogenic chemicals have been proposed as potential markers of human fecal contamination in recreational water. However, to date, there are no published studies describing their relationships with illness risks. Using a cohort of swimmers at seven U.S. beaches, we examined potential associations between the presence of chemical markers of human fecal pollution and self-reported gastrointestinal (GI) illness, diarrhea, and respiratory illness. Swimmers were surveyed about their beach activities, water exposure, and baseline symptoms on the day of their beach visit, and about any illness experienced 10–12 days later. Risk differences were estimated using model-based standardization and adjusted for the swimmer’s age, beach site, sand contact, rainfall, and water temperature. Sixty-two chemical markers were analyzed from daily water samples at freshwater and marine beaches. Of those, 20 were found consistently. With the possible exception of bisphenol A and cholesterol, no chemicals were consistently associated with increased risks of illness. These two chemicals were suggestively associated with 2% and 1% increased risks of GI illness and diarrhea in both freshwater and marine beaches. Additional research using the more sensitive analytic methods currently available for a wider suite of analytes is needed to support the use of chemical biomarkers to quantify illness risk and identify fecal pollution sources.

Alabama, Indiana, Michigan, Mississippi, Ohio, Rho↗
USGS1986

Regional resource depletion and industry activity: The case of oil and gas in the Gulf of Mexico

Stable and declining oil and gas prices have changed the industry's price expectations and, along with depletion of promising exploration prospects, has resulted in reduced exploration. Even with intensive additional exploration, production in most U.S. areas is expected to decline. What does this imply for the drilling and petroleum industry suppliers in particular regions? How should planners in government and the private sector project and incorporate the consequences of these changes in their strategies? This paper answers these questions for the industry operating in the offshore Gulf of Mexico. Future oil and gas production, as well as demand for offshore drilling and production facilities, are shown to depend on the size distribution of undiscovered fields, their associated production costs, and oil and gas prices. Declining well productivity is a consequence of development of progressively smaller fields so that long-run drilling demand should not decline in proportion to the expected production decline. Calculations show a substantial payoff to the drilling industry, in terms of potential demand increases, if it can develop and implement cost reducing technologies. Implications of these results for other offshore producing areas such as the North Sea are also discussed.

Socio-Economic Planning Sciences↗
USGS2002

Estradiol-induced gene expression in largemouth bass (Micropterus salmoides)

Vitellogenin (Vtg) and estrogen receptor (ER) gene expression levels were measured in largemouth bass to evaluate the activation of the ER-mediated pathway by estradiol (E2). Single injections of E2 ranging from 0.0005 to 5 mg/kg up-regulated plasma Vtg in a dose-dependent manner. Vtg and ER mRNAs were measured using partial cDNA sequences corresponding to the C-terminal domain for Vtg and the ligand-binding domain of ER?? sequences. After acute E2-exposures (2 mg/kg), Vtg and ER mRNAs and plasma Vtg levels peaked after 2 days. The rate of ER mRNA accumulation peaked 36-42 h earlier than Vtg mRNA. The expression window for ER defines the primary response to E2 in largemouth bass and that for Vtg a delayed primary response. The specific effect of E2 on other estrogen-regulated genes was tested during these same time windows using differential display RT-PCR. Specific up-regulated genes that are expressed in the same time window as Vtg were ERp72 (a membrane-bound disulfide isomerase) and a gene with homology to an expressed gene identified in zebrafish. Genes that were expressed in a pattern that mimics the ER include the gene for zona radiata protein ZP2, and a gene with homology to an expressed gene found in winter flounder. One gene for fibrinogen ?? was down-regulated and an unidentified gene was transiently up-regulated after 12 h of exposure and returned to basal levels by 48 h. Taken together these studies indicate that the acute molecular response to E2 involves a complex network of responses over time. ?? 2002 Elsevier Science Ireland Ltd. All rights reserved.

Molecular and Cellular Endocrinology↗
USGS2021

Groundwater dynamics at Kīlauea Volcano and vicinity, Hawaiʻi

Kīlauea Volcano, on the Island of Hawaiʻi, is surrounded and permeated by active groundwater systems that interact dynamically with the volcanic system. A generalized conceptual model of Hawaiian hydrogeology includes high-level dike-impounded groundwater, very permeable perched and basal aquifers, and a transition (mixing) zone between freshwater and saltwater. Most high-level groundwater is associated with the low-permeability intrusive complexes that underlie volcanic rift zones and calderas and also act to compartmentalize the groundwater system. Hydrogeologic studies of Kīlauea in recent decades, accompanied by deep research drilling, have shown that high-level groundwater is more widespread than once understood, that permeability decreases dramatically at depth, particularly in rift zones, and that freshwater can occur at depths of as much as several kilometers below the local water table. Copious groundwater recharge causes near-surface conductive heat flow to be near zero over much of Kīlauea. Approximately 95 percent of groundwater discharge occurs offshore, accompanied by approximately 99 percent of the approximately 6,000 megawatts of heat supplied by magmatic intrusion. Here, we summarize current understanding of the groundwater system of Kīlauea Volcano and describe transient changes during the decade or more preceding the 2018 eruption sequence. The changes in groundwater chemistry and thermal structure beneath Kīlauea summit hold implications for volcanic-volatile transport and the potential for explosive volcanism. Between 2008 and 2018, the magma conduit beneath the lava lake likely created an adjacent zone of very hot rock that significantly delayed liquid groundwater inflow to the draining magma conduit. Sulfate concentrations in groundwater beneath Kīlauea summit, sampled at the National Science Foundation-funded drill hole 1.5 kilometers south-southwest of the lava lake, declined substantially between 2010 and present. This decline likely reflects, at least in part, the decreased effectiveness of volatile condensation and solution into groundwater (scrubbing). The vent opening in 2008 presumably focused volatile flux into the vicinity of the vent, and progressive drying of the surroundings further restricted interaction with the groundwater system. The decrease in sulfate concentrations in the drill hole between 2010 and 2018 likely reflects decreased effectiveness of scrubbing.

Hawaii↗
USGS2016

A millennial-scale record of Pb and Hg contamination in peatlands of the Sacramento-San Joaquin Delta of California, USA

In this paper, we provide the first record of millennial patterns of Pb and Hg concentrations on the west coast of the United States. Peat cores were collected from two micro-tidal marshes in the Sacramento-San Joaquin Delta of California. Core samples were analyzed for Pb, Hg, and Ti concentrations and dated using radiocarbon, 210Pb, and 137Cs. Pre-anthropogenic concentrations of Pb and Hg in peat ranged from 0.60 to 13.0 µg g-1and from 6.9 to 71 ng g-1, respectively. For much of the past 6000+ years, the Delta was free from anthropogenic pollution, however, beginning in ~1425 CE, Hg and Pb concentrations, Pb/Ti ratios, Pb enrichment factors (EFs), and HgEFs all increased. Pb isotope compositions of the peat suggest that this uptick was likely caused by smelting activities originating in Asia. The next increases in Pb and Hg contamination occurred during the California Gold Rush (beginning ~1850 CE), when concentrations reached their highest levels (74 µg g-1 Pb, 990 ng g-1 Hg; PbEF = 12 and HgEF = 28). Lead concentrations increased again beginning in the ~1920s with the incorporation of Pb additives in gasoline. The phase-out of lead additives in the late 1980s was reflected in Pb isotope ratios and reductions in Pb concentrations in the surface layers of the peat. The rise and fall of Hg contamination was also tracked by the peat archive, with the highest Hg concentrations occurring just before 1963 CE and then decreasing during the post-1963 period. Overall, the results show that the Delta was a pristine region for most of its ~6700-year existence; however, since ~1425 CE, it has received Pb and Hg contamination from both global and regional sources.

California↗
USGS2019

Success of lake restoration depends on spatial aspects of nutrient loading and hydrology

Many aquatic ecosystems have deteriorated due to human activities and their restoration is often troublesome. It is proposed here that the restoration success of deteriorated lakes critically depends on hitherto largely neglected spatial heterogeneity in nutrient loading and hydrology. A modelling approach is used to study this hypothesis by considering four lake types with contrasting nutrient loading (point versus diffuse) and hydrology (seepage versus drainage). By comparing the longterm effect of common restoration measures (nutrient load reduction, lake flushing or biomanipulation) in these four lake types, we found that restoration through reduction of nutrient loading is effective in all cases. In contrast, biomanipulation only works in seepage lakes with diffuse nutrient inputs, while lake flushing will even be counterproductive in lakes with nutrient point sources. The main conclusion of the presented analysis is that a priori assessment of spatial heterogeneity caused by nutrient loading and hydrology is essential for successful restoration of lake ecosystems.

Science of the Total Environment↗
USGS2004

Developmental instability in Rhus copallinum L.: multiple stressors, years, and responses

Developmental instability, as assessed by leaf fluctuating asymmetry and stem internode allometry, was examined at nine sites, representing three levels of disturbance, over multiple years. Site selection was based on land‐use disturbance classes related to training of mechanized infantry and other land management activities at Fort Benning, Georgia. Developmental instability varied among sites and years, and there was a strong site‐by‐year interaction for many traits. Indeed, depending on the year, the same site could be ranked as having the greatest and least amount of leaf fluctuating asymmetry. Burning a site the year prior to collecting the leaves profoundly influenced measures of leaf fluctuating asymmetry. In the absence of recent burning, leaf fluctuating asymmetry declined with increasing disturbance, but burning the year prior to collecting the leaves reversed this trend. Total plant cover, proportion of bare ground, and amount of plant litter influenced the amount of leaf asymmetry in a site‐dependent manner. Overall, burning influenced the levels of developmental instability more than either disturbance or microhabitat variables such as total plant cover, which should reflect competition in a plant’s immediate neighborhood.

International Journal of Plant Sciences↗
USGS2016

Flood-inundation maps for the Peckman River in the Townships of Verona, Cedar Grove, and Little Falls, and the Borough of Woodland Park, New Jersey, 2014

Digital flood-inundation maps for an approximate 7.5-mile reach of the Peckman River in New Jersey, which extends from Verona Lake Dam in the Township of Verona downstream through the Township of Cedar Grove and the Township of Little Falls to the confluence with the Passaic River in the Borough of Woodland Park, were created by the U.S. Geological Survey (USGS) in cooperation with the New Jersey Department of Environmental Protection. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/ depict estimates of the probable areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage on the Peckman River at Ozone Avenue at Verona, New Jersey (station number 01389534). Near-real-time stages at this streamgage may be obtained on the Internet from the USGS National Water Information System at http://waterdata.usgs.gov/ . Flood profiles were simulated for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated using the most current stage-discharge relations at USGS streamgages on the Peckman River at Ozone Avenue at Verona, New Jersey (station number 01389534) and the Peckman River at Little Falls, New Jersey (station number 01389550). The hydraulic model was then used to compute eight water-surface profiles for flood stages at 0.5-foot (ft) intervals ranging from 3.0 ft or near bankfull to 6.5 ft, which is approximately the highest recorded water level during the period of record (1979–2014) at USGS streamgage 01389534, Peckman River at Ozone Avenue at Verona, New Jersey. The simulated water-surface profiles were then combined with a geographic information system digital elevation model derived from light detection and ranging (lidar) data to delineate the area flooded at each water level. The availability of these maps along with Internet information regarding current stage from the USGS streamgage provides emergency management personnel and residents with information, such as estimates of inundation extents, based on water stage, that is critical for flood response activities such as evacuations and road closures, as well as for post-flood recovery efforts.

New Jersey↗