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At least 523 records · Page 29Linked to original sources
USGS2010

Evaluation of the use of performance reference compounds in an oasis-HLB adsorbent based passive sampler for improving water concentration estimates of polar herbicides in freshwater

Passive samplers such as the Polar Organic Chemical Integrative Sampler (POCIS) are useful tools for monitoring trace levels of polar organic chemicals in aquatic environments. The use of performance reference compounds (PRC) spiked into the POCIS adsorbent for in situ calibration may improve the semiquantitative nature of water concentration estimates based on this type of sampler. In this work, deuterium labeled atrazine-desisopropyl (DIA-d5) was chosen as PRC because of its relatively high fugacity from Oasis HLB (the POCIS adsorbent used) and our earlier evidence of its isotropic exchange. In situ calibration of POCIS spiked with DIA-d5was performed, and the resulting time-weighted average concentration estimates were compared with similar values from an automatic sampler equipped with Oasis HLB cartridges. Before PRC correction, water concentration estimates based on POCIS data sampling ratesfrom a laboratory calibration exposure were systematically lower than the reference concentrations obtained with the automatic sampler. Use of the DIA-d5 PRC data to correct POCIS sampling rates narrowed differences between corresponding values derived from the two methods. Application of PRCs for in situ calibration seems promising for improving POCIS-derived concentration estimates of polar pesticides. However, careful attention must be paid to the minimization of matrix effects when the quantification is performed by HPLC-ESI-MS/MS. ?? 2010 American Chemical Society.

Environmental Science & Technology↗
USGS2009

Budget analysis of Escherichia coli at a southern Lake Michigan Beach

Escherichia coli (EC) concentrations at two beaches impacted by river plume dynamics in southern Lake Michigan were analyzed using three-dimensional hydrodynamic and transport models. The relative importance of various physical and biological processes influencing the fate and transport of EC were examined via budget analysis and a first-order sensitivity analysis of model parameters. The along-shore advective fluxofEC(CFU/m 2 ·s)was found to be higher compared to its crossshore counterpart; however, the sum of diffusive and advective components was of a comparable magnitude in both directions showing the importance of cross-shore exchange in EC transport. Examination of individual terms in the EC mass balance equation showed that vertical turbulent mixing in the water column dominated the overall EC transport for the summer conditions simulated. Dilution due to advection and diffusion accounted for a large portion of the total EC budget in the nearshore, and the net EC loss rate within the water column (CFU/m 3 ·s) was an order of magnitude smaller compared to the horizontal and vertical transport rates. This result has important implications for modeling EC at recreational beaches; however, the assessment of the magnitude of EC loss rate is complicated due to the strong coupling between vertical exchange and depth-dependent EC loss processes such as sunlight inactivation and settling. Sensitivity analysis indicated that solar inactivation has the greatest impact on EC loss rates. Although these results are site-specific, they clearly bring out the relative importance of various processes involved.

Environmental Science & Technology↗
USGS2002

Preferential dealkylation reactions of s-triazine herbicides in the unsaturated zone

The preferential dealkylation pathways of the s-triazine herbicides, atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), propazine [2-chloro-4,6-bis(isopropylamino)-s-triazine], and simazine [2-chloro-4,6-bis(ethylamino)-s-triazine], and two monodealkylated triazine metabolites, deisopropylatrazine (DIA: 2-amino-4-chloro-6-ethylamino-s-triazine) and deethylatrazine (DEA: 2-amino-4-chloro-6-isopropylamino-s-triazine) were investigated on two adjacent Eudora silt-loam plots growing corn (Zea mays L.). Results from the shallow unsaturated zone and surface-water runoff showed preferential removal of an ethyl side chain from atrazine, simazine, and DIA relative to an isopropyl side chain from atrazine, propazine, and DEA. It is hypothesized that deethylation reactions may proceed at 2-3 times the rate of deisopropylation reactions. It is concluded that small concentrations of DIA reportedly associated with the degradation of atrazine may be due to a rapid turnover rate of the metabolite in the unsaturated zone, not to small production levels. Because of continued dealkylation of both monodealkylated metabolites, a strong argument is advanced for the presence of a didealkylated metabolite in the unsaturated zone.

Environmental Science & Technology↗
USGS2002

Molecular weight, polydispersity, and spectroscopic properties of aquatic humic substances

The number- and weight-averaged molecular weights of a number of aquatic fulvic acids, a commercial humic acid, and unfractionated organic matter from four natural water samples were measured by high-pressure size exclusion chromatography (HPSEC). Molecular weights determined in this manner compared favorably with those values reported in the literature. Both recent literature values and our data indicate that these substances are smaller and less polydisperse than previously believed. Moreover, the molecular weights of the organic matter from three of the four natural water samples compared favorably to the fulvic acid samples extracted from similar environments. Bulk spectroscopic properties of the fulvic substances such as molar absorptivity at 280 nm and the E4/E6 ratio were also measured. A strong correlation was observed between molar absorptivity, total aromaticity, and the weight average molecular weights of all the humic substances. This observation suggests that bulk spectroscopic properties can be used to quickly estimate the size of humic substances and their aromatic contents. Both parameters are important with respect to understanding humic substance mobility and their propensity to react with both organic and inorganic pollutants.

Environmental Science & Technology↗
USGS2004

Differences in dissolved cadmium and zinc uptake among stream insects: Mechanistic explanations

This study examined the extent to which dissolved Cd and Zn uptake rates vary in several aquatic insect taxa commonly used as indicators of ecological health. We further attempted to explain the mechanisms underlying observed differences. By comparing dissolved Cd and Zn uptake rates in several aquatic insect species, we demonstrated that species vary widely in these processes. Dissolved uptake rates were not related to gross morphological features such as body size or gill size-features that influence water permeability and therefore have ionoregulatory importance. However, finer morphological features, specifically, the relative numbers of ionoregulatory cells (chloride cells), appeared to be related to dissolved metal uptake rates. This observation was supported by Michaelis-Menten type kinetics experiments, which showed that dissolved Cd uptake rates were driven by the numbers of Cd transporters and not by the affinities of those transporters to Cd. Calcium concentrations in exposure media similarly affected Cd and Zn uptake rates in the caddisfly Hydropsyche californica. Dissolved Cd and Zn uptake rates strongly co-varied among species, suggesting that these metals are transported by similar mechanisms.

Environmental Science & Technology↗
USGS2011

Environmental policy analysis, peer reviewed: Reservoir sediment cores show US lead declines

As a result of the Clean Air Act, lead (Pb) emissions to the atmosphere have been greatly reduced since the mid-1970s. As part of its National Water Quality Assessment, the U.S. Geological Survey has been using paleolimnological techniques to assess past trends in hydrophobic contaminants. In urban-suburban environments, reservoir sediment cores show prominent peaks in Pb distributions that correlate well with the rise and fall of leaded gasoline. However, Pb concentrations in sediments are approximately double those of baseline values prior to the 1950s and 1960s. It is apparent that significant concentrations of anthropogenic Pb still exist in soils and aquatic sediments and that it will take many years to reduce these concentrations to prepollution values, even if there are no new sources of Pb pollution.

Environmental Science & Technology↗
USGS1998

Enhanced dissolution of cinnabar (mercuric sulfide) by dissolved organic matter isolated from the Florida Everglades

Organic matter isolated from the Florida Everglades caused a dramatic increase in mercury release (up to 35 μM total dissolved mercury) from cinnabar (HgS), a solid with limited solubility. Hydrophobic (a mixture of both humic and fulvic) acids dissolved more mercury than hydrophilic acids and other nonacid fractions of dissolved organic matter (DOM). Cinnabar dissolution by isolated organic matter and natural water samples was inhibited by cations such as Ca 2+ . Dissolution was independent of oxygen content in experimental solutions. Dissolution experiments conducted in DI water (pH = 6.0) had no detectable (<2.5 nM) dissolved mercury. The presence of various inorganic (chloride, sulfate, or sulfide) and organic ligands (salicylic acid, acetic acid, EDTA, or cysteine) did not enhance the dissolution of mercury from the mineral. Aromatic carbon content in the isolates (determined by 13 C NMR) correlated positively with enhanced cinnabar dissolution. ζ-potential measurements indicated sorption of negatively charged organic matter to the negatively charged cinnabar (pH pzc = 4.0) at pH 6.0. Possible mechanisms of dissolution include surface complexation of mercury and oxidation of surface sulfur species by the organic matter.

Florida↗
USGS2025

Science needs for determining the effects of climate change on harmful algal blooms in the southeastern United States

The Southeastern United States has many lakes, streams, and reservoirs that serve as important drinking water sources with recreational, agricultural, and ecological uses. However, harmful algal blooms (HABs) are becoming more common in these waters, causing health issues for humans and animals. HABs have been listed as a contaminant of emerging concern, and the magnitude, frequency, and duration of HABs appear to be increasing at the global scale. While it is well known that nutrients stimulate algae growth, it is not clear how climate change and other parameters stimulate the development of toxin production by HABs. The scientific literature describes parameters, such as storm occurrence, temperature, dissolved metals, erosion of soils, increasing length of growing season, discharge, and hydroperiod, that may affect algae growth and toxin production. Climate and hydrologic models address many of the physical and environmental parameters that influence HABs, but no climate models directly address HABs. This report compiles information from the existing literature pertaining to HABs and the modeling and forecasting of HABS. This compilation is done through the incorporation of climate change models. HAB research that involves climate change will require multiple disciplines that bring together ecologists, hydrologists, climatologists, engineers, economists, and new technology. Resource managers could use geographic data about the occurrence and distribution of HABs to develop models that identify waterbodies more vulnerable to HAB events. Development of such models will require teams capable of integrating biological, chemical, and physical factors. Model development will require additional research that can resolve anthropogenic and climate-related environmental factors to identify trends in freshwater HABs. The complexity and interconnectedness of the parameters that influence HAB occurrences will make model development challenging and require rigorous regional calibration.

Open-File Report↗
USGS2015

Tracing the cycling and fate of the explosive 2,4,6-trinitrotoluene in coastal marine systems with a stable isotopic tracer, 15N-[TNT]

2,4,6-Trinitrotoluene (TNT) has been used as a military explosive for over a hundred years. Contamination concerns have arisen as a result of manufacturing and use on a large scale; however, despite decades of work addressing TNT contamination in the environment, its fate in marine ecosystems is not fully resolved. Here we examine the cycling and fate of TNT in the coastal marine systems by spiking a marine mesocosm containing seawater, sediments, and macrobiota with isotopically labeled TNT ( 15 N-[TNT]), simultaneously monitoring removal, transformation, mineralization, sorption, and biological uptake over a period of 16 days. TNT degradation was rapid, and we observed accumulation of reduced transformation products dissolved in the water column and in pore waters, sorbed to sediments and suspended particulate matter (SPM), and in the tissues of macrobiota. Bulk δ 15 N analysis of sediments, SPM, and tissues revealed large quantities of 15 N beyond that accounted for in identifiable derivatives. TNT-derived N was also found in the dissolved inorganic N (DIN) pool. Using multivariate statistical analysis and a 15 N mass balance approach, we identify the major transformation pathways of TNT, including the deamination of reduced TNT derivatives, potentially promoted by sorption to SPM and oxic surface sediments.

Environmental Science & Technology↗
USGS2016

Direct photolysis rates and transformation pathways of the lampricides TFM and niclosamide in simulated sunlight

The lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2′,5-dichloro-4′-nitrosalicylanilide (niclosamide) are directly added to many tributaries of the Great Lakes that harbor the invasive parasitic sea lamprey. Despite their long history of use, the fate of lampricides is not well understood. This study evaluates the rate and pathway of direct photodegradation of both lampricides under simulated sunlight. The estimated half-lives of TFM range from 16.6 ± 0.2 h (pH 9) to 32.9 ± 1.0 h (pH 6), while the half-lives of niclosamide range from 8.88 ± 0.52 days (pH 6) to 382 ± 83 days (pH 9) assuming continuous irradiation over a water depth of 55 cm. Both compounds degrade to form a series of aromatic intermediates, simple organic acids, ring cleavage products, and inorganic ions. Experimental data were used to construct a kinetic model which demonstrates that the aromatic products of TFM undergo rapid photolysis and emphasizes that niclosamide degradation is the rate-limiting step to dehalogenation and mineralization of the lampricide. This study demonstrates that TFM photodegradation is likely to occur on the time scale of lampricide applications (2–5 days), while niclosamide, the less selective lampricide, will undergo minimal direct photodegradation during its passage to the Great Lakes.

Environmental Science & Technology↗
USGS2019

Hydrocarbons in upland groundwater, Marcellus Shale Region, Northeastern Pennsylvania and Southern New York, USA

Water samples from 50 domestic wells located <1 km (proximal) and >1 km (distal) from shale-gas wells in upland areas of the Marcellus Shale region were analyzed for chemical, isotopic, and groundwater-age tracers. Uplands were targeted because natural mixing with brine and hydrocarbons from deep formations is less common in those areas compared to valleys. CH 4 -isotope, predrill CH 4 -concentration, and other data indicate that one proximal sample (5% of proximal samples) contains thermogenic CH 4 (2.6 mg/L) from a relatively shallow source (Catskill/Lock Haven Formations) that appears to have been mobilized by shale-gas production activities. Another proximal sample contains five other volatile hydrocarbons (0.03–0.4 μg/L), including benzene, more hydrocarbons than in any other sample. Modeled groundwater-age distributions, calibrated to 3 H, SF 6 , and 14 C concentrations, indicate that water in that sample recharged prior to shale-gas development, suggesting that land-surface releases associated with shale-gas production were not the source of those hydrocarbons, although subsurface leakage from a nearby gas well directly into the groundwater cannot be ruled out. Age distributions in the samples span ∼20 to >10000 years and have implications for relating occurrences of hydrocarbons in groundwater to land-surface releases associated with recent shale-gas production and for the time required to flush contaminants from the system.

New York, Pennsylvania↗
USGS2001

Rapid arsenite oxidation by Thermus aquaticus and Thermus thermophilus: Field and laboratory investigations

Thermus aquaticus and Thermus thermophilus, common inhabitants of terrestrial hot springs and thermally polluted domestic and industrial waters, have been found to rapidly oxidize arsenite to arsenate. Field investigations at a hot spring in Yellowstone National Park revealed conserved total arsenic transport and rapid arsenite oxidation occurring within the drainage channel. This environment was heavily colonized by Thermus aquaticus. In laboratory experiments, arsenite oxidation by cultures of Thermus aquaticus YT1 (previously isolated from Yellowstone National Park) and Thermus thermophilus HB8 was accelerated by a factor of over 100 relative to abiotic controls. Thermus aquaticus and Thermus thermophilus may therefore play a large and previously unrecognized role in determining arsenic speciation and bioavailability in thermal environments.

Environmental Science & Technology↗
USGS2009

Removal of organic wastewater contaminants in septic systems using advanced treatment technologies

The detection of pharmaceuticals and other organic wastewater contaminants (OWCs) in ground water and surface-water bodies has raised concerns about the possible ecological impacts of these compounds on nontarget organisms. On-site wastewater treatment systems represent a potentially significant route of entry for organic contaminants to the environment. In this study, effluent samples were collected and analyzed from conventional septic systems and from systems using advanced treatment technologies. Six of 13 target compounds were detected in effluent from at least one septic system. Caffeine, paraxanthine, and acetaminophen were the most frequently detected compounds, and estrogenic activity was detected in 14 of 15 systems. The OWC concentrations were significantly lower in effluent after sand filtration (p < 0.01) or aerobic treatment (p < 0.05) as compared with effluent that had not undergone advanced treatment. In general, concentrations in conventional systems were comparable to those measured in previous studies of municipal wastewater treatment plant (WWTP) influent, and concentrations in systems after advanced treatment were comparable to previously measured concentrations in WWTP effluent. These data indicate that septic systems using advanced treatment can reduce OWCs in treated effluent to similar concentrations as municipal WWTPs. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Journal of Environmental Quality↗
USGS2023

Assessment of lunar resource exploration in 2022

The idea of mining the Moon, once purely science-fiction, is now on the verge of becoming reality. Taking advantage of the resources on the Moon is part of the plans of many nations and some enterprising commercial entities; demonstrating in-situ (in place) resource utilization near the lunar south pole is an explicit goal of the United States’ Artemis program. Economic extraction and sustainable management of these resources require understanding the nature, quantity, and quality of each resource. This publication aims to provide a relatively simple, but technically rigorous, assessment of the status of lunar resource exploration in 2022. Building on the experience of the U.S. Geological Survey in conducting resource assessments for Earth, we propose a general methodology for quantitative lunar resources assessments. Lunar resources can be categorized as energy, mineral, and water and classified with respect to their certainty and their recoverability. The portion of the technically recoverable resource that can be converted to a commodity within budgetary and other mission constraints can be classified as a “reserve.” For energy resources, solar energy is known to be especially abundant along some high ridges near the lunar poles and the technology to exploit it is mature. Mineral resources, largely in the form of loose rock powder that covers the surface of the Moon, are also widely accessible in large quantities. Many different technologies to convert this material into useful commodities (such as landing pads and oxygen) are currently being developed and are likely to be available for industrial-scale application within 30 years. Water ice almost certainly exists in the polar regions of the Moon but there are fundamental unanswered questions about when and how the ice formed—leaving us without knowledge of the form, quantity, quality, and distribution of lunar ice. Until rover missions bring new ground truth data, lunar ice will remain a highly speculative resource that may be both limited and non-renewable.

Circular↗
USGS2018

U.S. Geological Survey continuous monitoring workshop—Workshop summary report

Executive Summary The collection of high-frequency (in other words, “continuous”) water data has been made easier over the years because of advances in technologies to measure, transmit, store, and query large, temporally dense datasets. Commercially available, in-situ sensors and data-collection platforms—together with new techniques for data analysis—provide an opportunity to monitor water quantity and quality at time scales during which meaningful changes occur. The U.S. Geological Survey (USGS) Continuous Monitoring Workshop was held to build stronger collaboration within the Water Mission Area on the collection, interpretation, and application of continuous monitoring data; share technical approaches for the collection and management of continuous data that improves consistency and efficiency across the USGS; and explore techniques and tools for the interpretation of continuous monitoring data, which increases the value to cooperators and the public. The workshop was organized into three major themes: Collecting Continuous Data, Understanding and Using Continuous Data, and Observing and Delivering Continuous Data in the Future. Presentations each day covered a variety of related topics, with a special session at the end of each day designed to bring discussion and problem solving to the forefront. The workshop brought together more than 70 USGS scientists and managers from across the Water Mission Area and Water Science Centers. Tools to manage, assure, control quality, and explore large streams of continuous water data are being developed by the USGS and other organizations and will be critical to making full use of these high-frequency data for research and monitoring. Disseminating continuous monitoring data and findings relevant to critical cooperator and societal issues is central to advancing the USGS networks and mission. Several important outcomes emerged from the presentations and breakout sessions.

Open-File Report↗
USGS2025

Bioaccumulation and transfer of per- and polyfluoroalkyl substances (PFAS) in a stream and riparian food web contaminated by food processing wastewater

We evaluated the bioaccumulation and transfer of per- and polyfluoroalkyl substances (PFAS) in a stream food web contaminated by a food processing facility. Abiotic (i.e., water, sediment, and foam) and biotic (i.e., algae, aquatic insect larvae and adults, fish, and riparian spiders) matrices were sampled upstream and downstream of the facility’s wastewater outfall. Compared with upstream, PFAS concentrations were 600-fold higher in downstream water (mean ∑ 40 PFAS 3.67 ng mL –1 ± 0.48 (standard error)) and reflected inputs from the outfall, with 6:2 fluorotelomer sulfonate (6:2 FTS) dominating the PFAS profile. Within the aquatic food web, perfluorooctanesulfonate (PFOS) was the most biomagnified, and 6:2 FTS was the most biodiluted. In contrast, insect-mediated transfer of PFAS to riparian spiders showed trophic enrichment of 6:2 FTS and dilution of PFOS. We observed significant positive associations between phospholipid membrane-water partition coefficient (log K MW ) and perfluoroalkyl carboxylate (PFCA) chain length on bioaccumulation across most biological matrices, demonstrating that these chemical parameters are predictive of PFAS bioaccumulation potential in the field. Our research reveals important differences in aquatic versus terrestrial exposure for certain PFAS and that biological processes (e.g., trophic interactions and metamorphosis) and chemical properties (e.g., chain length, log K MW , and concentration) control PFAS uptake, bioaccumulation, and transfer in linked freshwater and terrestrial ecosystems.

Environmental Science & Technology↗
USGS2003

Modeling precipitation and sorption of elements during mixing of river water and porewater in the Coeur d'Alene River basin

Reddish brown flocs form along the edge of the Coeur d'Alene River when porewater drains into river water during the annual lowering of water level in the basin. The precipitates are efficient scavengers of dissolved elements and have characteristics that may make metals associated with them bioavailable. This work characterizes the geochemistry of the porewater and models the formation and composition of the flocs. Porewater is slightly acidic, has suboxic to anoxic characteristics, tends to have higher alkalinity, and contains elevated concentrations of many constituents relative to river water. Laboratory mixing experiments involving porewater and river water were done to produce the precipitates. Thermodynamic predictions using PHREEQC indicate that predicted amounts of ferrihydrite and gibbsite agree with removal of Fe and Al. Predictions of element removal by adsorption onto ferrihydrite are consistent with observed removal using a combination of surface complexation constants for the generalized two-layer model (As and Se), alternative surface constants derived from experiments at high sorbate-to-sorbent ratios (Cd, Co, Cu, Ni, Pb, and Zn), and adjusted surface constants to fit experimental data (Cr, Mo, and Sb). This new set of surface complexation constants needs further testing in other contaminated systems.

Idaho↗
USGS2000

Carbonate ions and arsenic dissolution by groundwater

Samples of Marshall Sandstone, a major source of groundwater with elevated arsenic levels in southeast Michigan, were exposed to bicarbonate ion under controlled chemical conditions. In particular, effects of pH and redox conditions on arsenic release were evaluated. The release of arsenic from the aquifer rock was strongly related to the bicarbonate concentration in the leaching solution. The results obtained suggest that the carbonation of arsenic sulfide minerals, including orpiment (As2S3) and realgar (As2S2), is an important process in leaching arsenic into groundwater under anaerobic conditions. The arseno-carbonate complexes formed, believed to be As(CO3)2-, As(CO3)(OH)2-, and AsCO3+, are stable in groundwater. The reaction of ferrous ion with the thioarsenite from carbonation process can result in the formation of arsenopyrite which is a common mineral in arsenic-rich aquifers.Samples of Marshall Sandstone, a major source of groundwater with elevated arsenic levels in southeast Michigan, were exposed to bicarbonate ion under controlled chemical conditions. In particular, effects of pH and redox conditions on arsenic release were evaluated. The release of arsenic from the aquifer rock was strongly related to the bicarbonate concentration in the leaching solution. The results obtained suggest that the carbonation of arsenic sulfide minerals, including orpiment (As2S3) and realgar (As2S2), is an important process in leaching arsenic into groundwater under anaerobic conditions. The arseno-carbonate complexes formed, believed to be As(CO3)2-, As(CO3)(OH)2-, and AsCO3+, are stable in groundwater. The reaction of ferrous ion with the thioarsenite from carbonation process can result in the formation of arsenopyrite which is a common mineral in arsenic-rich aquifers.The role of bicarbonate in leaching arsenic into groundwater was investigated by conducting batch experiments using core samples of Marshall Sandstone from southeast Michigan and different bicarbonate solutions. The effects of pH and redox conditions on As dissolution were examined. Results showed that As was not leached significantly out of the Marshall Sandstone samples after 3 d using either deionized water or groundwater, but As was leached efficiently by sodium bicarbonate, potassium bicarbonate, and ferric chloride solutions. The leaching rate with sodium bicarbonate was about 25% higher than that with potassium bicarbonate. The data indicated that bicarbonate ion was involved primarily in As dissolution and that hydroxyl radical ion did not affect As dissolution to any significant degree. The amount of As leached was dependent upon the sodium bicarbonate concentration, increasing with reaction time for each concentration. Significant As leaching was found in the extreme pH ranges of <1.9 and 8.0-10.4. The resulting arseno-carbonate complexes formed were stable in groundwater.

Environmental Science & Technology↗