Search USGS⌕ Search

SEARCH · Search USGS

Results for “Environmental Chemistry”

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

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

At least 55 records · Page 3Linked to original sources
USGS2020

Surficial geochemistry and bioaccessibility of tellurium in semi-arid mine tailings

Tellurium (Te) is a critical element due to its use in solar technology. However, some forms are highly toxic. Few studies have examined Te behavior in the surficial environment, thus little is known about its potential human and environmental health impacts. This study characterizes two physicochemically distinct Te-enriched mine tailings piles (big and flat tailings) deposited by historic gold (Au) mining in the semi-arid Delamar mining district, Nevada. The big tailings are characterized by smaller particle size and higher concentrations of potentially toxic elements (up to 290 mg Te kg-1), which are enriched at the tailings surface. In contrast, the flat tailings have larger particle size and properties that are relatively invariant with depth. Based on the sulfate to sulfide ratio, the tailings were determined to be sulfate dominated suggesting a high degree of weathering, although the flat tailings did contain significant amounts of sulfides (~40%). Tellurium x-ray absorption spectroscopy of the big tailings indicates that tellurate, the less toxic Te species, is the principal form of Te. Electron microscopy indicates that most of the Te present at the site is associated with iron (oxy)hydroxides, sometimes with other potentially toxic elements, especially lead and antimony. Physiologically-based extraction tests indicate that substantially more Te is solubilized in synthetic stomach fluids than in lung fluids, with gastric bioaccessibility ranging from 13-31% of total Te. This points to low to medium bioaccessibility, which is common for iron (oxy)hydroxide associated elements. Together, these results represent a preliminary assessment of Te surficial behavior in a semi-arid environment and indicate that Te in these tailings represent a moderate health concern.

Environmental Chemistry↗
USGS2026

Polystyrene microplastics alter the accumulation and elimination dynamics of silver nanoparticles in Daphnia magna

Rationale Microplastics (MPs) can interact with engineered nanomaterials and alter their environmental fate and bioavailability. However, their influence on the bioaccumulation dynamics of silver nanoparticles (AgNPs) in aquatic filter feeders under environmentally relevant conditions remains poorly understood. We hypothesized that polystyrene microplastics (PS-MPs) alter the uptake, elimination and overall bioaccumulation dynamics of AgNPs in Daphnia magna . Methodology Adult D. magna were exposed to isotopically labeled citrate-coated 109 AgNPs in the presence and absence of PS-MPs. Waterborne uptake, dietary uptake, assimilation efficiency, food ingestion and elimination were quantified experimentally and incorporated into a biodynamic model to predict steady-state silver (Ag) concentrations under environmentally relevant exposure scenarios. Results PS-MPs increased waterborne Ag accumulation by approximately eightfold compared with AgNPs exposure alone. However, Ag elimination was substantially faster, with 98% of accumulated Ag eliminated after five days of depuration compared with 66% without PS-MPs. PS-MPs also reduced food ingestion rates (IRs), while assimilation efficiency remained largely unchanged. Biodynamic modeling predicted that steady-state Ag accumulation was approximately fivefold greater in the presence of PS-MPs, with waterborne exposure becoming the dominant accumulation pathway. Discussion These findings suggest that PS-MPs alter bioaccumulation dynamics of AgNPs in filter-feeding organisms by enhancing organism-associated Ag during waterborne exposure while accelerating Ag elimination, likely through particle-associated transport and gut egestion. Collectively, these results underscore the complexity of Ag bioaccumulation processes when MPs and AgNPs interact and highlight the importance of studies conducted under environmentally relevant conditions.

Environmental Chemistry↗
USGS2008

Studies on geological background and source of fluorine in drinking water in the North China Plate fluorosis areas

Endemic fluorosis in northern China is usually produced by high fluorine (F) content in drinking water. Thirty-one samples of drinking waters, mainly well waters and nearly 200 samples of rocks, loess, and coal were analyzed for F content using the combustion hydrolysis-fluoride-ion selective electrode (ISE) method. The geologic cross sections of two well-known fluorosis basins were studied. The solubility of F in different rock types collected from fluorosis areas was determined. Results showed that areas of endemic fluorosis in northern China are located in coal-bearing basins which are comprised of three stratagraphic portions. The lowest portion is Precambrian granitic rocks or Cambrian-Ordovician carbonates. The middle portion consists of Permo-Carboniferous or Jurassic coal-bearing sequences. The upper portion is 0-400 m Pleistocene loess. Flourine content in the Precambrian granite-gneiss contained (a) 1090-1460 ppm, in the Cambrian-Ordovician limestone and dolomite, (b) 52-133 ppm, in black shales and coal gob of Permo-Carboniferous coal-bearing strata, (c) 200-700 ppm, and (d) Pleistocene loess 454-542 ppm. The solubility of F in black shales of coal-bearing sequences was higher than in Precambrian granitic rocks, and both were more soluble than loess. F solubility from Precambrian granitic rocks was moderate, but Precambrian granitic rocks have high F content and thus contribute an appreciable amount of ion to the shallow groundwater (well water). Varying F content in shallow groundwater is controlled by geological conditions. The sources of F in the shallow groundwater from fluorosis areas in northern China are mainly derived from black shales of coal-bearing sequences and Precambrian granitic basement in the basins of northern China. ?? 2008 Taylor & Francis.

Toxicological and Environmental Chemistry↗
USGS2008

Exposure of mallards (Anas platyrhynchos) to the hepatotoxic cyanobacterium Nodularia spumigena

Nodularin (NODLN) is a cyclic pentapeptide hepatotoxin produced by the cyanobacterium Nodularia spumigena, which forms extensive blooms during the summer in the Baltic Sea. Nodularin was detected in liver, muscle and/or feather samples of several common eiders (Somateria mollissima) from the Gulf of Finland (northern Baltic Sea) in 2002-2005. Published information on the adverse effects of NODLN in marine birds is scarce. The aim of this study was to evaluate the toxicity of NODLN, and determine the concentrations of NODLN in liver and muscle tissue in mallards (Anas platyrhynchos) exposed to N. spumigena. Mallards received a single or multiple exposure via oral gavage with an aqueous slurry containing toxic N. spumigena. Dosages ranged from 200 to 600 ??g NODLN per kg body weight (bw). There were minimal histopathological changes in liver tissue, and brain cholinesterase activity did not differ among treatment groups. Concentrations of NODLN measured by LC-MS in liver varied between approximately 3-120 ??g kg-1 dry weight (dw) and ducks receiving multiple exposures had significantly greater liver toxin levels than ducks receiving the two lowest single exposures. In muscle, NODLN concentrations were approximately 2-6 ??g kg-1 dw, but did not differ significantly among exposure groups. This is the first in vivo lab study examining the effects and bioaccumulation of NODLN from N. spumigena in birds. The mallards in this study were resistant to adverse effects and did not bioaccumulate substantial levels of NODLN at the doses given. ?? 2008 Taylor & Francis.

Gulf of Finland↗
USGS2008

Phosphate bonding to goethite and pyrolusite surfaces

Fourier transform infrared (FTIR) spectra were obtained from pure and phosphated goethite ( α -FeOOH), and pyrolusite (MnO 2 ). The nature of the phosphate-surface bond was determined to be binuclear for goethite and bidentate for pyrolusite.

Toxicological and Environmental Chemistry↗
USGS1999

Determination of pesticides associated with suspended sediments in the San Joaquin River, California, USA, using gas chromatography-ion trap mass spectrometry

An analytical method useful for the quantification of a range of pesticides and pesticide degradation products associated with suspended sediments was developed by testing a variety of extraction and cleanup schemes. The final extraction and cleanup methods chosen for use are suitable for the quantification of the listed pesticides using gas chromatography-ion trap mass spectrometry and the removal of interfering coextractable organic material found in suspended sediments. Methylene chloride extraction followed by Florisil cleanup proved most effective for separation of coextractives from the pesticide analytes. Removal of elemental sulfur was accomplished with tetrabutylammonium hydrogen sulfite. The suitability of the method for the analysis of a variety of pesticides was evaluated, and the method detection limits (MDLs) were determined (0.1-6.0 ng/g dry weight of sediment) for 21 compounds. Recovery of pesticides dried onto natural sediments averaged 63%. Analysis of duplicate San Joaquin River suspended-sediment samples demonstrated the utility of the method for environmental samples with variability between replicate analyses lower than between environmental samples. Eight of 21 pesticides measured were observed at concentrations ranging from the MDL to more than 80 ng/g dry weight of sediment and exhibited significant temporal variability. Sediment-associated pesticides, therefore, may contribute to the transport of pesticides through aquatic systems and should be studied separately from dissolved pesticides.

Toxicological and Environmental Chemistry↗
USGS1999

The distribution of, and relation among, mercury and methylmercury, organic carbon, carbonate, nitrogen and phosphorus, in periphyton of the south Florida ecosystem

Periphyton samples from Water Conservation Areas, Big Cypress National Preserve, and Everglades National Park in south Florida were analyzed for concentrations of total mercury, methylmercury, nitrogen, phosphorus, organic carbon, and inorganic carbon. Concentrations of total mercury in periphyton decrease slightly along a gradient from north‐to‐south. Both total mercury and methylmercury are positively correlated with organic carbon, nitrogen and phosphorus in periphyton. In horizontal sections of periphyton mats, total mercury concentrations tend to be largest at the tops and bottoms of the mats. Methylmercury concentrations tend to be the largest near the bottom of mats. These localized elevated concentrations of methylmercury suggest that there are “hot spots”; of methylmercury in periphyton.

Florida↗
USGS1999

Copper, lead, mercury and zinc in periphyton from the south Florida ecosystem

Periphyton samples from the Big Cypress National Preserve were analyzed for concentrations of copper, lead, zinc, mercury, and methylmercury. Concentrations of organic carbon, inorganic carbon, nitrogen, and phosphorus in periphyton samples also were determined. The samples were extracted with sodium acetate solution at a pH of 5.5 to determine exchangeable and carbonate phase metal concentrations in periphyton. Total metal concentrations in the periphyton were directly related to the degree of calcite saturation in the water column. Exchangeable and carbonate phase metal concentrations were directly related to the percent inorganic carbon in the samples. A connection between the geochemistry of trace metals and calcite precipitation and dissolution is suggested.

Toxicological and Environmental Chemistry↗
USGS2014

Bouse Formation in the Bristol basin near Amboy, California, USA

Limestone beds underlain and overlain by alluvial fan conglomerate near Amboy, California, are very similar in many respects to parts of the Bouse Formation, suggesting that an arm of the Pliocene Bouse water body extended across a wide part of the southern Mojave Desert. The deposits are north of the town of Amboy at and below an elevation of 290 m, along the northern piedmont of the Bristol “dry” Lake basin. The Amboy outcrops contain the Lawlor Tuff (4.83 Ma), which is also found in an outcrop of the Bouse Formation in the Blythe basin near Buzzards Peak in the Chocolate Mountains, 180 km southeast of Amboy. Bouse exposures near Amboy are ∼3.4 m thick, white, distinctly bedded, with limestone and calcareous sandstone as well as stromatolite mounds; we interpret these as nearshore deposits. The Bouse at Amboy contains ostracodes, diatoms, and mollusks that indicate saline lake or estuarine environments with an admixture of fresh-water forms. Along with wading bird tracks and a spine from a marine fish, these fossils suggest that the deposits formed in saline waters near a fresh-water source such as a perennial stream. Beds of the outcrop dip southward and are 113 m above the surface of Bristol Playa, where similar age sediments are buried 270+ m deep, indicating significant faulting and vertical tectonics in this part of the Eastern California Shear Zone during the past 5 m.y. Confirmation of the Bouse Formation at Amboy strengthens previous assignments to the Bouse Formation for mudstones in driller logs at Danby “dry” Lake, California, and suggests that areally extensive arms of the Bouse water body were west of the Blythe basin. The Bristol basin arm of the lower Bouse basin probably was restricted from the main water body by narrow passages, but Bouse sediment there is similar to that in the Blythe basin, suggesting generally similar water chemistry and environmental conditions. Examining the degree to which Bouse deposits in the western arms differed from Bouse deposits in the Blythe basin offers an approach to test whether the southernmost Bouse water body was deposited in an estuarine or lacustrine setting.

California↗
USGS2022

Detecting algal toxins and organic contaminants of concern in the environment

The U.S. Geological Survey (USGS) Kansas Water Science Center Organic Geochemistry Research Laboratory (OGRL) was established in 1987. The OGRL is a multidisciplinary program that contributes knowledge about the distribution, fate, transport, and effects of new and understudied organic compounds that may affect human health and (or) ecosystems. The OGRL consists of two units: Algal and Other Environmental Toxins Unit and Environmental Organic Chemistry Unit. The OGRL does independent and collaborative research, develops robust analytical methods, and provides fee-for-service analytical laboratory analyses.

Fact Sheet↗
USGS2023

Using mercury stable isotope fractionation to identify the contribution of historical mercury mining sources present in downstream water, sediment and fish

Ecosystems downstream of mercury (Hg) contaminated sites can be impacted by both localized releases as well as Hg deposited to the watershed from atmospheric transport. Identifying the source of Hg in water, sediment, and fish downstream of contaminated sites is important for determining the effectiveness of source-control remediation actions. This study uses measurements of Hg stable isotopes in soil, sediment, water, and fish to differentiate between Hg from an abandoned Hg mine from non-mine-related sources. The study site is located within the Willamette River watershed (Oregon, United States), which includes free-flowing river segments and a reservoir downstream of the mine. The concentrations of total-Hg (THg) in the reservoir fish were 4-fold higher than those further downstream (>90 km) from the mine site in free-flowing sections of the river. Mercury stable isotope fractionation analysis showed that the mine tailings (δ 202 Hg: −0.36‰ ± 0.03‰) had a distinctive isotopic composition compared to background soils (δ 202 Hg: −2.30‰ ± 0.25‰). Similar differences in isotopic composition were observed between stream water that flowed through the tailings (particulate bound δ 202 Hg: −0.58‰; dissolved: −0.91‰) versus a background stream (particle-bound δ 202 Hg: −2.36‰; dissolved: −2.09‰). Within the reservoir sediment, the Hg isotopic composition indicated that the proportion of the Hg related to mine-release increased with THg concentrations. However, in the fish samples the opposite trend was observed—the degree of mine-related Hg was lower in fish with the higher THg concentrations. While sediment concentrations clearly show the influence of the mine, the relationship in fish is more complicated due to differences in methylmercury (MeHg) formation and the foraging behavior of different fish species. The fish tissue δ 13 C and Δ 199 Hg values indicate that there is a higher influence of mine-sourced Hg in fish feeding in a more sediment-based food web and less so in planktonic and littoral-based food webs. Identifying the relative proportion of Hg from local contaminated site can help inform remediation decisions, especially when the relationship between total Hg concentrations and sources do not show similar covariation between abiotic and biotic media.

Oregon↗