SEARCH · USGS Science

Results for “Environmental Pollution”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources

USGS2022

Seed treatments containing neonicotinoids and fungicides reduce aquatic insect richness and abundance in midwestern USA–managed floodplain wetlands

Agrochemicals including neonicotinoid insecticides and fungicides are frequently applied as seed treatments on corn, soybeans, and other common row crops. Crops grown from pesticide-treated seed are often directly planted in managed floodplain wetlands and used as a soil disturbance or food resource for wildlife. We quantified invertebrate communities within mid-latitude floodplain wetlands and assessed their response to use of pesticide-treated seeds within the floodplain. We collected and tested aqueous and sediment samples for pesticides in addition to sampling aquatic invertebrates from 22 paired wetlands. Samples were collected twice in 2016 (spring [pre-water level drawdown] and autumn [post-water level flood-up]) followed by a third sampling period (spring 2017). Meanwhile, during the summer of 2016, a portion of study wetlands were planted with either pesticide-treated or untreated corn seed. Neonicotinoid toxic equivalencies (NI-EQs) for sediment ( X̅ = 0.58 μg/kg), water ( X̅ = 0.02 μg/L), and sediment fungicide concentrations ( X̅ = 0.10 μg/kg) were used to assess potential effects on wetland invertebrates. An overall decrease in aquatic insect richness and abundance was associated with greater NI-EQs in wetland water and sediments, as well as with sediment fungicide concentration. Post-treatment, treated wetlands displayed a decrease in insect taxa-richness and abundance before recovering by the spring of 2017. Information on timing and magnitude of aquatic insect declines will be useful when considering the use of seed treatments for wildlife management. More broadly, this study brings attention to how agriculture is used in wetland management and conservation planning.

Missouri↗

USGS2022

Toxicological responses to sublethal anticoagulant rodenticide exposure in free-flying hawks

An important component of assessing the hazards of anticoagulant rodenticides to non-target wildlife is observations in exposed free-ranging individuals. The objective of this study was to determine whether environmentally realistic, sublethal first-generation anticoagulant rodenticide (FGAR) exposures via prey can result in direct or indirect adverse effects to free-flying raptors. We offered black-tailed prairie dogs ( Cynomys ludovicianus ) that had fed on Rozol® Prairie Dog Bait (Rozol, 0.005% active ingredient chlorophacinone, CPN) to six wild-caught red-tailed hawks (RTHA, Buteo jamaicensis ), and also offered black-tailed prairie dogs that were not exposed to Rozol to another two wild-caught RTHAs for 7 days. On day 6, blood was collected to determine CPN’s effects on blood clotting time. On day 7, seven of the eight RTHAs were fitted with VHF radio telemetry transmitters and the RTHAs were released the following day and were monitored for 33 days. Prothrombin time (PT) and Russell’s viper venom time confirmed that the CPN-exposed RTHAs were exposed to and were adversely affected by CPN. Four of the six CPN-exposed RTHAs exhibited ptiloerection, an indication of thermoregulatory dysfunction due to CPN toxicity, but no signs of intoxication were observed in the reference hawk or the remaining two CPN-exposed RTHAs. Of note is that PT values were associated with ptiloerection duration and frequency; therefore, sublethal CPN exposure can directly or indirectly evoke adverse effects in wild birds. Although our sample sizes were small, this study is a first to relate coagulation times to adverse clinical signs in free-ranging birds.

Colorado↗

USGS2023

Atmospheric mercury and its deposition during the phasing out of an amalgam electrolysis plant: Temporal, seasonal, and spatial patterns

Large amounts of mercury (Hg) were consumed and emitted into the atmosphere during the process of amalgam electrolysis used to produce chlorine and caustic soda since the nineteenth century. In Europe, amalgam electrolysis has been gradually replaced by advanced Hg-free technologies. In this work, we describe changes in atmospheric Hg and bulk Hg wet deposition during the phasing out of an amalgam electrolytic production line of a chlor-alkali plant in Neratovice, Czech Republic, central Europe. Bulk wet deposition Hg near the chlor-alkali plant was low at 3.6 ± 0.8 μg m −2 year −1 due in part to low annual precipitation amounts (486 ± 97 mm) in the period 2015–2021. Nevertheless, Hg deposition was elevated relative to a nearby reference site both before and after decommissioning of the electrolytic line. Switching off the amalgam electrolytic line did not notably affect bulk wet deposition Hg near the chlor-alkali plant. Levels of gaseous elemental Hg (GEM) and particle-bound Hg (PBM) monitored seasonally four times per year over 24-h time periods indicated rapid declines in four nearby settlements set in cardinal directions from the Hg emission source. Mean atmospheric GEM and PBM concentrations decreased rapidly from 9.0 ± 2.1 ng m −3 and 243 ± 255 pg m −3 in the period 2013–2017 when amalgam electrolysis was operating to 3.3 ± 0.4 ng m −3 and 32 ± 6 pg m −3 in the period 2018–2021 after its decommissioning in November 2017. Seasonal changes of GEM coincided with changes in temperature with the highest concentrations in summer, while PBM air levels were lowest in summer due to the highest seasonal precipitation amount. GEM concentrations at the four monitored settlements at Neratovice remained elevated at 2.8 ng m −3 with respect to regional background, but PBM levels decreased to background levels.

Neratovice↗

USGS2024

Tissue distribution and temporal and spatial assessment of per- and polyfluoroalkyl substances (PFAS) in smallmouth bass (Micropterus dolomieu) in the mid-Atlantic United States

Per- and polyfluoroalkyl substances (PFAS) have become an environmental issue worldwide. A first step to assessing potential adverse effects on fish populations is to determine if concentrations of concern are present in a region and if so, in which watersheds. Hence, plasma from adult smallmouth bass Micropterus dolomieu collected at 10 sites within 4 river systems in the mid-Atlantic region of the United States, from 2014 to 2019, was analyzed for 13 PFAS. These analyses were directed at better understanding the presence and associations with land use attributes in an important sportfish. Four substances, PFOS, PFDA, PFUnA, and PFDoA, were detected in every plasma sample, with PFOS having the highest concentrations. Sites with mean plasma concentrations of PFOS below 100 ng/ml had the lowest percentage of developed landcover in the upstream catchments. Sites with moderate plasma concentrations (mean PFOS concentrations between 220 and 240 ng/ml) had low (< 7.0) percentages of developed land use but high (> 30) percentages of agricultural land use. Sites with mean plasma concentrations of PFOS > 350 ng/ml had the highest percentage of developed land use and the highest number PFAS facilities that included military installations and airports. Four of the sites were part of a long-term monitoring project, and PFAS concentrations of samples collected in spring 2017, 2018, and 2019 were compared. Significant annual differences in plasma concentrations were noted that may relate to sources and climatic factors. Samples were also collected at two sites for tissue (plasma, whole blood, liver, gonad, muscle) distribution analyses with an expanded analyte list of 28 PFAS. Relative tissue distributions were not consistent even within one species of similar ages. Although the long-chained legacy PFAS were generally detected more frequently and at higher concentrations, emerging compounds such as 6:2 FTS and GEN X were detected in a variety of tissues.

Delaware, Maryland, New York, Pennsylvania, Virgin↗

USGS2026

Impact of fog on California waterfowl flight activity: Historical and modern insights into effects post-Clean Air Act

Since establishment of the Clean Air Act in the early 1970s, occurrence of the dense ‘Tule Fog’, historically prevalent throughout winter across California’s Central Valley, has substantially reduced. At the same time, waterfowl body masses have generally increased. Flight is metabolically expensive, and fog visually and navigationally impairs birds in flight, likely causing them to remain aloft for longer than usual periods. If less fog results in less flight and reduced energy expenditure, then fewer winter Tule fog events could contribute to increased body masses of California waterfowl since the mid-1980’s. Therefore, we aimed to assess the relationship between waterfowl flight and fog occurrence/density with historic (1991–93) and modern (2015–23) waterfowl tracking data in the Central Valley of California (CCV). Historic tracking data showed that the probability of flight increased with increasing fog density. Birds were significantly more likely to fly in fog than when there was no fog and most likely to fly in heavy fog . Modern data showed similar responses to fog with flight occurring significantly more during dawn fog events. This relationship between improved waterfowl body mass and fewer fog events may provide an opportunity to redirect scarce funding to focus on other population requirements such as improving habitats for nesting, molting and brood rearing that are currently lacking. Unanticipated benefits of the Clean Air Act should stand as a strong recommendation to maintaining this Act into the future.

California↗

USGS2012

Hydrozincite seasonal precipitation at Naracauli (Sardinia – Italy): Hydrochemical factors and morphological features of the biomineralization process

Hydrozincite [Zn 5 (CO 3 ) 2 (OH) 6 ] precipitation from Naracauli waters (SW Sardinia) is, among other things, promoted by a microbial community made up of a filamentous cyanobacterium ( Scytonema sp.) and a microalgae ( Chlorella sp.). Hydrozincite bioprecipitation is responsible for the natural removal of harmful metals, especially Zn, from the stream waters. Thus, hydrozincite could be used to attenuate metal pollution in mining waters. Information on environmental conditions which promote the biomineralization process is fundamental for the development of remediation strategies. This paper aims to investigate the variables controlling the biomineralization process, and seasonal variation of the hydrochemical factors that affect hydrozincite precipitation. Hydrozincite morphology varies depending on the environmental conditions. Specifically, changes were observed between samples collected in late spring and samples collected in summer, and among samples precipitated under different water flow conditions. According to field observations, correlated with speciation and equilibrium calculation, the maximum intensity in hydrozincite precipitation occurs in the late spring during rainy years. In these conditions, the hydraulic regime in the stream reaches stationary conditions, and saturation index values with respect to hydrozincite reach their highest values. Concomitantly, the Zn 2+ / CO 3 2 - "> CO32- molar ratio reaches values close to 1, indicating that kinetic processes have a role on the hydrozincite biomineralization process.

Sardinia↗

USGS2003

Effects of ultraviolet radiation on toad early life stages

Background Exposure to harmful levels of ultraviolet-B radiation (UVB), a component of solar radiation, has been suggested as a potential cause of amphibian declines. Methods We measured solar radiation (UVB, ultraviolet-A, and visible) wavebands in breeding ponds of Bufo boreas (boreal toad, a montane species that has undergone severe population declines) and Bufo woodhousii (Woodhouse’s toad, a plains toad that has not experienced declines) and examined tolerances of these species to simulated solar UVB exposures in the laboratory. Results We found larvae of both species to be tolerant of simulated solar UVB in excess of solar UVB levels observed in their breeding ponds. B. boreas tadpoles were more tolerant of simulated solar UVB exposure than B. woodhousii tadpoles, possibly because of greater amounts of photoprotective melanin in B. boreas skin. Conclusions UVB levels observed in B. boreas habitats do not currently appear to constitute a threat to the survival of these animals; however, long-term (>1 month) exposure to UVB levels comparable to levels associated with the water interface appears to reduce survival in B. woodhousii tadpoles. Therefore, future increases in surface and water column UVB radiation in bufonid habitats might pose significant survival risks to B. boreas or B. woodhousii populations.

Environmental Science and Pollution Research↗

USGS2003

Effects of a fire-retardant chemical to fathead minnows in experimental streams

Background Each year millions of liters of fire-retardant chemicals are applied to wildfires across the nation. Recent laboratory studies with long-term fire-retardant chemicals indicate a significant photoenhanced toxicity of products containing sodium ferrocyanide corrosion inhibitors. Our objective of this study was to determine the toxicity of fire-retardant chemicals to fathead minnows during exposure in experimental outdoor streams. Methods Stream tests were conducted to determine the potential toxicity of a pulse of exposure as might occur when fire retardant chemical is rinsed from the watershed by rainfall. Two artificial 55-meter experimental streams were dosed with different concentrations of Fire-Trol® GTS-R, or uncontaminated for a control. Replicate groups of fathead minnows were added to screened containers (10 fish per container) and exposed to retardant chemicals in the recirculating flow of the stream for up to 6 hours. Results and Discussion Under field conditions toxicity of GTS-R only occurred in the presence of sunlight. When GTS-R was tested on sunny days, 100% mortality occurred. However, when tested during heavily overcast conditions, no mortality occurred. Conclusions Lethal concentrations of cyanide were measured when GTS-R with YPS exposures were conducted under sunny conditions, but not under cloudy conditions, indicating that a minimum UV level is necessary to induce toxicity as well as the release of cyanide from YPS. The toxicity observed with GTS-R was likely associated with lethal concentrations of cyanide. Rainwater runoff following applications of this fire-retardant at the recommended rate could result in lethal concentrations in small ponds and streams receiving limited water flow under sunny conditions.

Environmental Science and Pollution Research↗

USGS2006

Arsenic speciation in arsenic-rich Brazilian soils from gold mining sites under anaerobic incubation

Background. Arsenic speciation in environmental samples is essential for studying toxicity, mobility and bio-transformation of As in aquatic and terrestrial environments. Although the inorganic species As(III) and As(V) have been considered dominant in soils and sediments, organisms are able to metabolize inorganic forms of arsenic into organo-arsenic compounds. Arsenosugars and methylated As compounds can be found in terrestrial organisms, but they generally occur only as minor constituents. We investigated the dynamics of arsenic species under anaerobic conditions in soils surrounding gold mining areas from Minas Gerais State, Brazil to elucidate the arsenic biogeochemical cycle and water contamination mechanisms. Methods. Surface soil samples were collected at those sites, namely Paracatu Formation, Banded Iron Formation and Riacho dos Machados Sequence, and incubated in CaCl2 2.5 mmol L-1 suspensions under anaerobic conditions for 1, 28, 56 and 112 days. After that, suspensions were centrifuged and supernatants analyzed for soluble As species by IC-ICPMS and HPLC-ICPMS. Results. Easily exchangeable As was mainly arsenite, except when reducible manganese was present. Arsenate was mainly responsible for the increase in soluble arsenic due to the reductive dissolution of either iron or manganese in samples from the Paracatu Formation and Riacho dos Machados Sequence. On the other hand, organic species of As dominated in samples from the Banded Iron Formation during anaerobic incubation. Discussion. Results are contrary to the expectation that, in anaerobic environments, As release due to the reductive dissolution of Fe is followed by As(V) reduction to As(III). The occurrence of organo-arsenic species was also found to be significant to the dynamics of soluble arsenic, mainly in soils from the Banded Iron Formation (BIF), under our experimental conditions. Conclusions. In general, As(V) and organic As were the dominant species in solution, which is surprising under anaerobic conditions in terrestrial environments. The unexpected occurrence of organic species of As was attributed to enrollment of ternary organic complexes or living organisms such as algae or cyanobacteria. Perspectives. These findings are believed to be useful for remediation strategies in mine-affected regions, as the organic As species are in general considered to be less toxic than inorganic ones and even As(V) is considered less mobile and toxic than As(III). ?? 2007 ecomed publishers (Verlagsgruppe Hu??thig Jehle Rehm GmbH).

Environmental Science and Pollution Research↗

USGS2007

Toxicity of cobalt-complexed cyanide to Oncorhynchus mykiss , Daphnia magna , and Ceriodaphnia dubia : Potentiation by ultraviolet radiation and attenuation by dissolved organic carbon and adaptive UV tolerance

Background Cobalt cyanide complexes often result when ore is treated with cyanide solutions to extract gold and other metals. These have recently been discovered in low but significant concentrations in effluents from gold leach operations. This study was conducted to determine the potential toxicity of cobalt-cyanide complexes to freshwater organisms and the extent to which ultraviolet radiation (UV) potentiates this toxicity. Tests were also conducted to determine if humic acids or if adaptation to UV influenced sensitivity to the cyanide complexes. Methods Rainbow trout ( Oncorhynchus mykiss ), Daphnia magna , and Ceriodaphnia dubia were exposed to potassium hexacyanocobaltate in the presence and absence of UV radiation, in the presence and absence of humic acids. Cyano-cobalt exposures were also conducted with C. dubia from cultures adapted to elevated UV. Results With an LC 50 concentration of 0.38 mg/L, cyanocobalt was over a 1000 times more toxic to rainbow trout in the presence of UV at a low, environmentally relevant irradiance level (4 μW/cm 2 as UVB) than exposure to this compound in the absence of UV with an LC 50 of 112.9 mg/L. Toxicity was immediately apparent, with mortality occurring within an hour of the onset of exposure at the highest concentration. Fish were unaffected by exposure to UV alone. Weak-acid dissociable cyanide concentrations were observed in irradiated aqueous solutions of cyanocobaltate within hours of UV exposure and persisted in the presence of UV for at least 96 hours, whereas negligible concentrations were observed in the absence of UV. The presence of humic acids significantly diminished cyanocobalt toxicity to D. magna and reduced mortality from UV exposure. Humic acids did not significantly influence survival among C. dubia . C. dubia from UV-adapted populations were less sensitive to metallocyanide compounds than organisms from unadapted populations. Conclusions The results indicate that metallocyanide complexes may pose a hazard to aquatic life through photochemically induced processes. Factors that decrease UV exposure such as dissolved organic carbon or increased pigmentation would diminish toxicity.

Environmental Science and Pollution Research↗

USGS2014

Burrowing mayfly populations in Chequamegon Bay, Wisconsin: 2002 and 2012

Burrowing mayflies (Ephemeroptera: Ephemeridae) are sensitive to pollution and have been used as environmental indicators in the Great Lakes. Hexagenia limbata and Ephemera simulans population abundance and biomass estimates from Chequamegon Bay, Lake Superior, were compared between the years 2002 and 2012 as well as inside and outside the Northern States Power Lakefront Superfund site. Mean abundance was similar and mean biomass of Ephemeridae was slightly less in 2012 than in 2002, most likely due to the occurrence of E. simulans in 2012, a smaller species not collected in 2002. In 2012, mean ephemerid abundance and biomass outside the Superfund site was significantly higher than inside the Superfund site. Biomass was higher in clay, clay with sand, and sand with clay substrates than in fine sand, coarse sand, or wood debris substrates. Substrate in the Superfund site was predominantly wood debris. Future monitoring of ephemerid populations in Chequamegon Bay, and particularly in the Superfund site as clean up begins, would be valuable to establish long-term population trends for these two species and potentially shed light on the habitat requirements of E. simulans , an understudied species in the Great Lakes.

Chequamegon Bay;Great Lakes;Lake Superior↗

USGS2006

Cell proliferation detected with flow cytometric cell cycle analysis and immunohistochemical detection of Proliferating Cell Nuclear Antigen (PCNA) from somatic tissues of Eastern Oysters, Crassostrea virginica

Two novel biomarker of response assays were developed and compared for use with bivalves. Bivalve mollusks are often used as bioindicators to monitor contaminant body burdens and are employed globally in pollution monitoring and as sentinels of environmental quality. The prevalence of proliferating cells in tissues of the eastern oyster, Crassostrea virginica , (n = 10) was investigated by using immunohistochemical staining of proliferating cell nuclear antigen (PCNA) and by flow cytometric analysis of DNA in cell cycle phases. The PCNA protein is highly conserved and central to DNA synthesis in dividing cells. This protein was detected by using a commercial antibody in the histological staining of gills, mantle, digestive gland, stomach, and labial palps. Cells obtained from these same organs and from the hearts of the oysters were used for flow cytometry (FCM). The proportions of nuclei in the S plus G2/M and G2/M fractions were compared with percentages of PCNA-positive cells scored through microscopy. Proliferation responses generated by microscopy and FCM (S plus G2/M) were equal for digestive gland, gills, stomach, and mantle. The proliferation response in labial palps was significantly higher by PCNA microscopy than by DNA FCM (S plus G2/M). For PCNA microscopy results, a significantly higher proliferation response was noted both for labial palps as compared to gills and mantle and for stomach and digestive gland as compared to gills (P < 0.005). For DNA FCM results, the percentages of proliferating cells in G2M fractions were significantly higher for labial palps and heart when compared to gills, mantle, and digestive gland. By FCM (S plus G2M), the percentages of proliferating cells followed a similar trend, although no significant differences were found between organs. The choice of a relatively highly proliferative tissue, such as labial palps as determined by this study, has utility for developing a cell line, for examining proliferation as a biomarker due to stressor impacts in feral oysters, and for detecting impacts of compounds on proliferative mechanisms.

Environmental Bioindicators↗

USGS1970

Hydrologic implications of solid-water disposal

The disposal of more than 1,400 million pounds of solid wastes in the United States each day is a major problem. This disposal in turn often leads to serious health, esthetic, and environmental problems. Among these is the pollution of vital ground-water resources. Of the six principal methods of solid-waste disposal in general use today, four methods-open dumps, sanitary landfill, incineration, and onsite disposal-carry an inherent potential for pollution of water resources. Seepage of rainwater through the wastes leaches undesirable constituents which reach the ground water in the area. This leachate is generally both biologically and chemically contaminated. The extent of the pollution from this leachate is largely dependent upon the geologic environment in which the solid wastes are deposited. Pollution potential is highest in permeable areas with a shallow water table where the wastes are in direct contact with the ground water. In a relatively impermeable area, the pollution is generally confined locally to the vicinity of the waste-disposal site. Site selection for disposal of solid wastes must be based on adequate water-resources information if pollutional potential is to be minimized. This will require regional as well as localized data on the water resources of the area. Only through such an approach can adequate protection be afforded to the environment in general and the water resources in particular.

Circular↗

USGS1992

Reconnaissance investigation of volatile and semivolatile organic compounds in the Memphis Aquifer at Alamo, Crockett County, Tennessee

Samples of ground water and soil gas were analyzed to study the occurrence of volatile and semivolatile organic compounds in the Memphis aquifer at Alamo in western Tennessee in 1989. At Alamo, the aquifer is locally unconfined. Four wells screened in the Memphis aquifer provided Alamo with 0.3 million gallons of water per day. Trichloroethylene (TCE), dichloroethylene, trichloroethane, and tetrachloroethylene were detected in water samples from two of the wells. In September 1989, the TCE concentration in a sample from well 1 was 45 micrograms per liter (mg/L); Tennessee’s maximum contaminant level for TCE in drinking water is 5 mg/L Concentrations of TCE in water from this well ranged from 40 to 113 mg/L during I988 and 1989. TCE concentration in water collected from well 2 in September 1989 was 0.7 mg/L During I988 and 1989, TCE concentrations in this well ranged from less than 0.5 to 5.1 mg/L None of the semivolatile organic compounds on the U.S. Environmental Protection Agency’s priority-pollutant list were detected in water from well 1. Soil gas was sampled at a depth of 3.5 feet below land surface in areas of suspected ground-water contamination. Analyses by gas chromatography indicated the presence of TCE in soils about 230 feet east of well 1 in the area of a former industrial site where solvents were handled. TCE concentrations in the soil gas of this area ranged from 0.2 to 30 mg/L TCE was not detected in soil gas near any of the wells. Depth to water at the wells ranged from 39 to 49 feet. The regional direction of ground-water flow is to the west-southwest, which would cause contaminants dissolved in ground water below the former industrial-site area to be transported toward the public-supply wells. Probable reasons contributing to the lack of TCE detection in soil gas at wells 1 and 2 are the relatively low concentrations of TCE in ground water at the wells and the vertical distance between sampling points and the water table.

Tennessee↗

USGS1996

Water-quality assessment of the Albemarle-Pamlico drainage basin, North Carolina and Virginia; trace elements in Asiatic clam (Corbicula fluminea) soft tissues and redbreast sunfish (Lepomis auritus) livers, 1992-93

The analysis of potential contaminants in biological tissues is an important part of many water-quality assessment programs, including the National Water-Quality Assessment (NAWQA) Program. Tissue analyses often are used to provide information about (1) direct threats to ecosystem integrity, and (2) the occurrence and distribution of potential contaminants in the environment. During 1992-93, trace elements in Asiatic clam (Corbicula fluminea) soft tissues and redbreast sunfish (Lepomis auritus) livers were analyzed to obtain information about the occurrence and distribution of trace element contaminants in the Albemarle-Pamlico Drainage Basin of North Carolina and Virginia. The investigation was conducted as part of the NAWQA Program. All but 3 of the 22 trace elements that were analyzed were detected. Although all 10 of the U.S. Environmental Protection Agency (U.S. EPA) priority pollutants were detected in the tissues sampled, they were present in relatively low concentrations. Concentrations of U.S. EPA priority pollutants in Asiatic clams collected in the Albemarle-Pamlico Drainage Basin are similar to concentrations observed in other NAWQA study units in the southeastern United States. Mercury (a U.S. EPA priority pollutant) was widely detected, being present in 29 of 30 tissue samples, but concentrations did not exceed the FDA action level for mercury of a risk-based screening value for the general public. Mercury concentrations in Asiatic clams were similar to concentrations in other NAWQA study areas in the Southeast.

North Carolina, Virginia↗

USGS2015

Trace-metal and organic constituent concentrations in bed sediment at Big Base and Little Base Lakes, Little Rock Air Force Base, Arkansas—Comparisons to sediment-quality guidelines and indications for timing of exposure

This report compares concentrations for a wide range of inorganic and organic constituents in bed sediment from Big Base Lake and Little Base Lake, which are located on Little Rock Air Force Base, Arkansas, to sediment-quality guidelines. This report also compares trace-metal concentrations in a bed-sediment core sample to sediment age to determine when the highest concentrations of trace metals were deposited in Big Base Lake. Trace-metal results often were higher than background concentrations in the surrounding Pulaski County area, and concentrations of arsenic, cadmium, cobalt, copper, lead, manganese, mercury, nickel, and zinc at one or more of three study sites were higher than median concentrations for a study involving 98 urban streams in seven metropolitan areas of the United States. Concentrations for most polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides in all three bed-sediment samples were less than the laboratory reporting limit or were detected at low concentrations. Some contaminants were detected at concentrations that are potentially toxic to sediment-dwelling biota; however, in general, the analyses suggest that the risk of sediment toxicity may be relatively low. Threshold effect concentrations were exceeded for 14 constituents—arsenic, copper, lead, nickel, and zinc, five polycyclic aromatic hydrocarbons compounds, chlordane, and all three dichlorodiphenyltrichloroethane (DDT) congeners—which suggests potential toxicity to some sediment-dwelling biota. Only two constituents had concentrations that exceeded published probable effect concentrations—arsenic (at the deepest site in Big Base Lake, NS6) and p,p’-dichlorodiphenyldichloroethylene (p,p’-DDE; at both sites in Big Base Lake, NS5 and NS6). Regarding highest concentrations and associated timing of exposure, trace metals analyzed in the sediment core seem to indicate three fairly distinct exposure patterns. For 11 trace metals that had the highest concentration measured in the shallowest and most recently deposited sediment, the most likely explanation is recent exposure by anthropogenic activities. Most of the 11 trace metals with highest concentrations in shallow sediment are relatively innocuous; however, arsenic, copper, selenium, and zinc are among the U.S. Environmental Protection Agency’s 126 priority pollutants. For three trace metals (cadmium, lead, and mercury), for which concentrations were highest in sediments that were 16–20 centimeters down the core, it is likely that a source associated with those contaminants during the period when those sediments were deposited, was reduced or eliminated. The eight remaining trace metals, for which concentrations were highest in sediments that were just below the prereservoir surface, likely had sources that were eliminated soon after lake construction or occurred at relatively high background concentrations in soils in the area around Little Rock Air Force Base.

Arkansas↗

USGS1984

Ground-water-quality appraisal of sand-plain aquifers in Hubbard, Morrison, Otter Tail, and Wadena Counties, Minnesota

Water samples were collected periodically from 124 wells completed in sand-plain aquifers in Hubbard, Morrison, Otter Tail, and Wadena Counties, Minnesota, to determine baseline water quality, provide data for evaluation of trends, and to investigate seasonal variations in concentrations of selected chemical constituents during a 3-year study that began in October 1979. Results of the study show that the water is predominantly a calcium bicarbonate type with low to moderate concentrations of dissolved solids (77 to 710 milligrams per liter), and that it generally is suitable chemically for most uses. Concentrations of most constituents are below limits for domestic consumption recommended by the Minnesota Pollution Control Agency and the U.S. Environmental Protection Agency. Concentrations of nitrite plus nitrate nitrogen, iron, and manganese in localized areas, however, exceed the recommended limits. Comparison of current data to historical data indicates that concentrations of nitrite plus nitrate nitrogen and chloride have increased in local agricultural areas. Data indicate that concentrations of certain chemical constituents vary seasonally and annually with changes in ground-water levels. This relationship suggests that chemicals infiltrate the land surface and percolate to the water table during major recharge events. Site-specific investigations at the Staples Irrigation Center near Staples, Minnesota, indicate that, in addition to seasonal variation, nitrite plus nitrate nitrogen and chloride concentrations decreased with depth while iron concentrations increased. Although no direct quantifiable relationship between concentration and depth was found, mean nitrite plus nitrate nitrogen and chloride concentrations were both 15 milligrams per liter near the top of the aquifer and were 0.1 and 3.5 milligrams per liter, respectively, near the bottom; mean concentrations of dissolved iron were 460 ug/L near the top of the aquifer and 3840 ug/L near the bottom. Data show that the stratification with depth of nitrite plus nitrate nitrogen, chloride, and iron exists at least several hundred feet from the source area throughout most of the year. Chemical stratification appears to be greatest during periods of little recharge.

Minnesota↗

USGS1995

Data and statistical summaries of background concentrations of metals in soils and streambed sediments in part of Big Soos Creek drainage basin, King County, Washington

Twenty-nine soil samples from 14 holes at 9 sites in part of the Big Soos Creek drainage basin in southwest King County, Washington, were collected and analyzed to obtain data on the magnitude and variability of background concentrations of metals in soils. Seven streambed-sediment samples and three streamwater samples from three sites also were collected and analyzed. These data are needed by regulating government agencies to determine if soils at sites of suspected contamination have elevated concentrations of metals, and to evaluate the effectiveness of remediation at sites with known contamination. Concentrations of 43 metals were determined by a total method, and concentrations of 17 metals were determined by a total-recoverable method and two different leaching methods. Metals analyzed for by all methods included most of those on the U.S. Environmental Protection agency list of priority pollutants, plus alluminum, iron, and manganese. Ranges of concentrations of metals determined by the total method are within ranges found by others for the conterminous United States. Concentrations of mercury, manganese, phosphorus, lead, selenium, antimony, and zinc as determined by the total method, and of some of these plus other metals as determined by the other methods were larger in shallow soil (less than 12 inches deep) than in deep soil (greater than 12 inches). Concentrations of metals in streambed sediments were more typical of shallow than deep soils.

Water-Resources Investigations Report↗