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Emerging and low-carbon technologies and innovations are driving a need for domestic sources, sustainable use, and availability of critical minerals (CMs)—those vital to the national and economic security of the United States. Understanding the known and potential health effects of exposures to such mineral commodities can inform prudent and environmentally responsible handling and harvesting. We review the occurrence, use, predominant exposure pathways, and adverse outcome pathways (AOP) for human and fish receptors of those CMs that are nutritionally essential trace metals (specifically, cobalt, chromium, manganese, nickel, and zinc), as well as the rare earth elements. Biological responses to some elements having comparable biogeochemistry can sometimes be similar. Candidate quantifiable biomarkers for assessing potential AOP are conveyed. [ABSTRACT FROM AUTHOR]

Background: The legalization of medicinal or recreational marijuana across many states in the United States and other countries has driven demand for cannabis, hemp, and related products. Objective: In the absence of federal regulations to ensure the product quality and safety of these products, each state issues its own guidance and sets its own regulations. Like food and pharmaceuticals, cannabis testing should include the analysis of heavy metals, which may be toxic if ingested or inhaled. Methods: Based on established methods for the preparation and multi-elemental analysis of plant materials, a range of cannabis and cannabis-related products were prepared for analysis using microwave-assisted acid digestion followed by testing with inductively coupled plasma-mass spectrometry (ICP-MS). The sample preparation procedure was validated by measuring arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) in four plant-based certified reference materials (CRMs). Results: The mean ICP-MS results for As, Cd, Hg, and Pb were in good agreement (85-110%) with the certified concentrations. The accuracy and precision of the ICP-MS method for the determination of As, Cd, Hg, and Pb, as well as other elements, were tested by spiking the various cannabis samples at different concentration levels and determining the spike recoveries. The spike recoveries for As, Cd, Hg, and Pb in all spiked samples met the AOAC Standard Method Performance Requirements (SMPRVR) for Determination of Heavy Metals in a Variety of Cannabis and Cannabis-Derived Products (SMPR 2020.001) of 60-115% for low-level spike and 80-115% for mid- and high-level spikes. Conclusion: Microwave-assisted acid digestion and ICP-MS are suitable for trace metal preparation and analysis of cannabis, as well as related products, as shown by the results of this method. The repeatability and recovery results for As, Cd, Hg, and Pb met the method requirement criteria in the AOAC SMPR 2020.001. This method can be used for all stages of production to ensure safety with respect to toxic metals. Highlights: A wide range of cannabis and hemp samples, from raw materials to finished products, are within scope for analysis using the microwave-assisted acid digestion/ICP-MS method. [ABSTRACT FROM AUTHOR]

Manganese (Mn) concentrations and the probability of arsenic (As) exceeding the drinking‐water standard of 10 μg/L were predicted in the Mississippi River Valley alluvial aquifer (MRVA) using boosted regression trees (BRT). BRT, a type of ensemble‐tree machine‐learning model, were created using predictor variables that affect Mn and As distribution in groundwater. These variables included iron (Fe) concentrations and specific conductance predicted from previously developed BRT models, groundwater flux and age estimates from MODFLOW, and hydrologic characteristics. The models also included results from the first airborne geophysical survey conducted in the United States to target an entire aquifer system. Predictions of high Mn and As occurred where Fe was high. Predicted high Mn concentrations were correlated with fraction of young groundwater (less than 65 years) computed from MODFLOW results. High probabilities of As exceedance were predicted where groundwater was relatively old and airborne electromagnetic resistivity was high, typically proximal to streams. Two‐variable partial‐dependence plots and sensitivity analysis were used to provide insight into the factors controlling Mn and As distribution in groundwater. The maps of predicted Mn concentrations and As exceedance probabilities can be used to identify areas where these constituents may be high, and that could be targeted for further study. This paper shows that incorporation of a selected set of process‐informed data, such as MODFLOW results and airborne geophysics, into a machine‐learning model improves model interpretability. Incorporation of process‐rich information into machine‐learning models will likely be useful for addressing a wide range of problems of interest to groundwater hydrologists. Article impact statement: Machine‐learning models trained on output from geophysical surveys, MODFLOW, and water‐quality predictions can be used to map trace metals. [ABSTRACT FROM AUTHOR]

Cigarette smoking is the most commonly used form of tobacco in the world. It is practiced by a large portion of the population, especially young people. These people often ignore or disregard the harmful toxic impacts that cigarettes have on both themselves and the environment. The United States Center for Disease Control estimates that nearly 40 million U.S. adults still smoke cigarettes, with nearly 1600 U.S. youth starting cigarette smoking every day. Although it is well-known that smoking cigarettes is addictive and leads to a numerous health conditions including cancer, chronic pulmonary and heart disease, the effect of disposing the cigarette debris in the environment is not very well investigated. It is well known that tobacco smoke contains more than 7000 chemical components of which 250 of the components are harmful to human health. Therefore, there is a need to monitor the toxic elements in these residues, as it relates to the impact of cigarette smoking to the health of the smokers and the public health impact of society. Considering that college students are more likely to be smokers this study targeted a college campus in Southwest Louisiana, USA that still allows smoking on campus. The campus site chosen was McNeese State University with the typical younger college student population. Sample collection was done by distributing cigarette butt sample collection buckets throughout the campus for three weeks in March of 2018. The samples collected were then microwave digested with trace metal grade nitric acid, filtered with 0.45 µm filter and analyzed by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) for the following trace elements As, Cd, Cr, Cu, Mn, Ni, Pb and Zn. [ABSTRACT FROM AUTHOR]

Biosolids are used to improve soil physical and chemical properties. Analysis of biosolids-amended soils from multiple regions of United States using consistent analytical methods is lacking. This Study determined long-term biosolids application on soil pH, electrical conductivity (EC), carbon, cadmium, copper, lead, and zinc concentrations in soils from two regions in United States. At one region, little difference was observed in pH and EC between biosolids-amended surface soils and control, the second region ranged from 5.46 to 7.87 and 50.2 to 402 µS cm−1 respectively. Trace metal levels at this region ranged from 0.76 to 3.79, 8.7 to 54.1, 15.2 to 53.9, and 26 to 207 mg kg−1 for Cadmium, Copper, lead and Zinc respectively; with its carbon levels ranging from 14.5 to 90.0 g kg−1. Metal levels were within the standards for residential occupation with the 40 Code of Federal Regulations (CFR) Part 503 and should not affect soil and groundwater quality. [ABSTRACT FROM AUTHOR]

A conceptual framework is proposed to investigate the accountability of business improvement district (BID) in urban governance networks and it is applied in analyses of BID state enabling laws in the United States. The conditions that lead to their emergence and the enhancement of their functions and how BIDs and their accountability issues should be conceptualized are discussed. The multidimensional framework proposed in this study includes political and bureaucratic accountability, transparency, liability, and responsiveness mechanisms. The results of the analyses show that the laws rely primarily on political and bureaucratic control mechanisms and provide some transparency mechanisms. The problems in implementing the bureaucratic and political control mechanisms are elaborated. The implications of the findings for future empirical studies are discussed. [ABSTRACT FROM AUTHOR]

Silver coins minted in the United States between 1837 and 1964 are comprised of 90% silver and 10% copper by law, but the presence of contamination with trace metals is likely. A collection of coins minted between 1841–1921 were analyzed for trace metal content using a handheld XRF device. A series of nine ten-cent coins were also analyzed using ICP-MS to relate the XRF response to metal ion concentrations. A linear correlation between lead concentration to XRF response allowed for quantitation of lead contamination. Greater amounts of lead were seen in coins minted prior to 1900 than in coins minted in the 20th century. In addition, two coins minted in 1854 were found contaminated with large amounts of either zinc or iron. The significance of these findings relative to silver sources and refining methods is discussed. [ABSTRACT FROM AUTHOR]

Across the United States, road palliatives are applied to roads for maintenance operations that improve road safety. In the winter, solid rock salts and brine solutions are used to reduce the accumulation of snow and ice, while in the summer, dust suppressants are used to minimize fugitive dust emissions. Many of these products are chloride-based salts that have been linked to freshwater salinization, toxicity to aquatic organisms, and damage to infrastructure. To minimize these impacts, organic products have been gaining attention, though their widespread adoption has been limited due to their higher cost. In some states, using produced water from conventionally drilled oil and gas wells (OGPWs) on roads is permitted as a cost-effective alternative to commercial products, despite its typically elevated concentrations of heavy metals, radioactivity, and organic micropollutants. In this study, 17 road palliatives used for winter and summer road maintenance were collected and their chemical composition and potential human toxicity were characterized. Results from this study demonstrated that liquid brine solutions had elevated levels of trace metals (Zn, Cu, Sr, Li) that could pose risks to human and environmental health. The radium activity of liquid calcium chloride products was comparable to the activity of OGPWs and could be a significant source of radium to the environment. The organic fractions of evaluated OGPWs and chloride-based products posed little risk to human health. However, organic-based dust suppressants regulated toxicity pathways related to xenobiotic metabolism, lipid metabolism, endocrine disruption, and oxidative stress, indicating their use could lead to environmental harm and health risks to operators handing these products and residents living near treated roads. [Display omitted] • Road palliatives are used to improve road surfaces during winter & summer months. • Chloride-based brines had elevated levels of trace metals. • Calcium chloride brines had similar radium activity as oil & gas produced water. • Organic fraction of brines, oil & gas wastewater pose little risk to human health. • Organic-based dust suppressants strongly activated 4 toxicity pathways. [ABSTRACT FROM AUTHOR]

Purpose: Beryllium (Be) and lead (Pb) sorption is important to the utility of the radioisotopes of these elements for sediment fingerprinting. This paper examines the sorption of Be and Pb exposed to fluvial sediment under varying chemical conditions representative of freshwater streams draining two distinct Critical Zone environments in the eastern United States: the mid-Atlantic piedmont and heavily glaciated Great Lakes region. Materials and methods: Batch experiments were completed using well-characterized in-stream deposit sediments collected from these two systems and varying solutions to reflect background and elevated levels of iron oxide in the form of goethite across times ranging from 0.25 to 360 h. The mid-Atlantic piedmont sediment had further treatments testing dissolved organic carbon and increased sediment to solution ratio effects on Pb and Be sorption. Results and discussion: Beryllium partition coefficients (Kd) ranged from a log Kd of 1.46 to 3.48 L kg−1 and Pb ranged from 0 to 5.03 L kg−1 across all treatments displaying several noticeable patterns. Two-stage sorption was observed such that sorption increased over time across all treatments and substrates. Goethite additions either enhanced or reduced sorption relative to the unaltered treatment depending on the original sediment and mixing time. Lead sorption with the addition of 100 mg of goethite increased during shorter mixing times before being surpassed by the unaltered, or base, treatment at longer mixing times for both the mid-Atlantic piedmont and glaciated Great Lakes sediment. Beryllium sorption was increased with the mid-Atlantic piedmont sediment whereas it was primarily decreased with the glaciated Great Lakes sediment. The 1 mg of goethite generally showed equal to or slightly enhanced sorption relative to the base setup of both Pb and Be with the exception of Pb sorption to the Great Lakes sediment. The highest DOC concentration tested of 11.86 mg L−1 retained a greater amount of Be and Pb in solution compared to other treatments after 360 h. Increasing the sediment to solution ratio showed decreased partition coefficients across all analogous times for Be compared to the base treatment whereas Pb sorption surpassed the unaltered treatment after 24 h. Conclusions: These results suggest that fluvial sediment mineralogy, organic matter concentration, and biogeochemical cycling of common stream chemical constituents may play a role in the mobilization or retention of these two trace metals and alter their utility for sediment fingerprinting. [ABSTRACT FROM AUTHOR]

This study reports data from the Upper Cambrian Conasauga Group and overlying Copper Ridge Formation of the Central Appalachian region, eastern U.S.A. Geochemical, isotopic and petrographic analysis of core material was carried out to constrain the extent of marine anoxia and to characterize sediment fluxes on the carbonate platform and continental shelf of Laurentia contemporaneous with the Steptoean Positive Carbon Isotope Excursion (SPICE), a Late Cambrian global marine anoxic event. Carbonate rocks (primarily dolostone) record a positive δ13C carb excursion starting in the middle Nolichucky Formation, reaching its peak (+4.3‰) at the boundary between the Maynardville and Copper Ridge formations. Strontium isotope ratios in the dolostone units are only slightly offset from the expected Cambrian seawater values, suggesting minimal post-diagenetic disturbance of isotopic and trace element systematics. Selective leaching of carbonate units reveal upward decreasing trends in dissolved redox-sensitive trace metals (e.g., U, Ni, V) indicative of drawdown from regional and global marine anoxia during the peak of the Late Cambrian SPICE event. • Dolomitized Cambrian sediments from Appalachia, USA preserve seawater chemistry. • Laurentian dolomites record the Steptoean Positive Carbon Isotope Excursion (SPICE). • 87Sr/86Sr of dolomite indicates preservation of marine geochemical/isotopic signals. • The stratigraphy records a global drawdown of redox-sensitive elements during SPICE. • Drawdown of oceanic trace nutrients may have impacted post-SPICE ocean productivity. [ABSTRACT FROM AUTHOR]

In December 2008, the failure of a coal ash retention pond at the Kingston Fossil Plant in eastern Tennessee, United States contaminated the Emory River and Clinch River located upstream of the Watts Bar Reservoir on the Tennessee River. Despite an extensive cleanup effort, further leaching of metals to river water from residual coal ash remains a cause of concern. Also, it is unknown whether coal ash has undergone substantial burial by younger river sediments. In order to address these uncertainties, in spring 2016 we collected six 30 cm long sediment cores from five contaminated and one uncontaminated portions of the river systems. The cores were subdivided into ∼2–3 cm sediment layers, which were exposed to water and acid leaching for metal and metalloid analyses. The measured concentrations of arsenic are 10 times higher in the river sediments near the Kingston Plant compared to downstream locations. Using ratios of various metals (e.g., cadmium, chromium, selenium, vanadium) to arsenic, we have established that only arsenic and selenium in downstream sediments are predominantly sourced by coal ash (80–100%). For other metals (e.g., cadmium, chromium, vanadium) coal ash-derived contamination comprises <20% of the total metal concentrations, which are likely of other anthropogenic origin. Under current conditions, the ash from the 2008 spill appears to be buried by 13–18 cm of natural sediment in downstream locations. However, elevated ash and metal and metalloid concentrations are still present in the shallow sediments (0–3 cm) in a close proximity to the Kingston Plant, suggesting redistribution of coal ash from further upstream. Overall, much higher concentrations of metals and metalloids were observed in the acid leachates compared to smaller, if any, concentrations in water-soluble fractions, suggesting that they may not be easily released to the water column. Through comparisons of metal and metalloid concentrations in raw coal ash and river sediments that had been in the river for 2 years, it appears that their quantities are similar. This implies that the majority of coal ash associated metals and metalloids are not mobilized by river waters. • Elevated As is elevated in shallow sediments in the center of coal ash spill. • Further downstream the coal ash is buried by ∼13 cm of natural sediment. • Metals are strongly adsorbed or incorporated into acid soluble phases. [ABSTRACT FROM AUTHOR]

Abstract It is widely agreed that the Earth's atmosphere and oceans have undergone major redox changes over the last 2.5 billion years. However, the magnitude of these shifts remains a point of debate because it is difficult to reconstruct concentrations of dissolved O 2 from indirect proxies in sedimentary archives. In this study, we show that an additional complicating factor that is rarely considered may be the pH of the water column. We analyzed rock samples from the early Jurassic Towaco Formation in the Newark basin (eastern USA), comprising deposits of a rift lake that became temporarily redox stratified. New biomarker evidence points to increasingly saline aquatic conditions during the second half of the lake's history. Salinity stratification likely induced redox stratification, consistent with the disappearance of macrofauna at this time. Distinctive lipid biomarker assemblages and stable nitrogen isotope data support previous mineralogical indications that the lake was alkaline (pH ≥ 9) during its saline episode. Despite the biomarker and macrofaunal evidence for anoxia, ratios of Fe/Al and Fe HR /Fe T show only small to no enrichments in the anoxic horizon compared to oxic facies in the same section – counter to what is commonly observed in anoxic marine settings. Molybdenum, As, V, U and to some degree Cd show enrichments in the anoxic interval, whereas Co, Ni, Cu, Zn and Cr do not. These patterns are most parsimoniously explained by differential pH effects on the solubility of these elements. Extrapolating from these observations in lacustrine strata, we speculate that a secular increase in seawater pH over Earth's history as recently proposed may have helped modulate the magnitude of trace metal enrichments in marine shales, although other factors such as atmospheric and oceanic redox likely dominated the observed enrichment patterns. Further, a decrease in the solubility of ferrous iron, a major O 2 sink, with increasing pH may have contributed to ocean oxygenation. In summary, our results highlight the potential importance of pH in influencing global biogeochemical cycles for multiple elements, including the ancient nitrogen isotope record. [ABSTRACT FROM AUTHOR]

The effects of varying concentrations (ranging from 0 to 10 μM) of two different metals that is, iron (Fe) and copper (Cu) on indigenous bacterial populations and their hydrolytic enzyme activities within the bacterioplankton assemblages from the surface waters of the Kalamazoo River were examined under controlled microcosm conditions. The two metals were added to water samples collected from the Kalamazoo River and examined for bacterial abundance and leucine aminopeptidase activities at various time intervals over a 48 h incubation period in the dark. Results revealed no concentration effects on the bacterial populations in the presence of both Fe and Cu, although the bacterial numbers varied significantly over time in both microcosms. Conversely, leucine aminopeptidase activities based on post‐hoc tests using Bonferroni correction revealed significant differences to increasing concentrations of both metals over the study period. These results further validate previous knowledge regarding the importance of various metal ions in regulating bacterial community structures and also suggest that aminopeptidase have the potential of effectively functioning using diverse trace and heavy metals as extracellular peptidase cofactors in aquatic systems. [ABSTRACT FROM AUTHOR]

Increasing anthropogenic alteration has resulted in increased exposure to both point and nonpoint source pollution. These exposures are increasingly studied for their role in human diseases, including diseases with known genetic or lifestyle risk factors. This study analyzed associations between a variety of human diseases and trace metals, PCBs, and PAHs in soil, groundwater, sediment, and fish. Contaminant spatial data at the county level from Virginia were used in ArcGIS to identify these associations among socially vulnerable populations. The neurologic and psychiatric disorders and cognitive markers were associated with numerous metals in groundwater/soil and/or aquatic system contaminants. Cancer death rates, fetal deaths, and infant deaths were also related to multiple environmental exposures from both categories of exposure. In contrast, many of the chronic diseases which are primarily attributed to lifestyle showed little association with these exposures with the exception of COPD which did appear to be associated with multiple metal exposures. Asthma showed similar associations compared to COPD. Our data suggest that within the context of socially vulnerable populations, where disease burden is often highest, exposures to metals, PAHs, and PCBs may play a role in the development or exacerbation of several highly prevalent categories of disease. These environmental exposures likely act through a variety of pathways all generally leading to increased oxidative stress, inflammation, or interference with biological systems and a subsequent role in disease development. [ABSTRACT FROM AUTHOR]

Variability in detrital trace-metal (TM) concentrations adversely affects the accuracy and uncertainty of using TM concentrations in siliciclastic marine sediments to decipher paleoceanographic conditions. Here we analyze massive TM datasets for rocks, soils, and stream sediments collected across the conterminous United States to quantify the effects of weathering and fluvial transport on the concentrations and variabilities of commonly used TMs (Al, Ti, Ba, Cr, Fe, Li, Ni, U, V) in detrital materials. Titanium (Ti) is preferred as the normalization element due to its lower mobility compared to aluminum (Al). Median TM/Ti ratios decrease by up to 25% from solid rocks to fluvial sediments, while standard deviations (SD) decrease by up to 90%, indicating that weathering and fluvial transport reduce not only TM/Ti ratios but also their ranges of variation. At a regional scale, median TM/Ti ratios in soils and sediments deviate significantly from commonly used global standards (Post-Archean Australian Shales and Upper Continental Crust). This means that, for normalization purposes, it is necessary to constrain the detrital TM/Ti ratios for each drainage basin under study rather than making use of a global standard. Sensitivity analyses demonstrate that the modification of median TM/Ti by weathering and fluvial transport processes can lead to significant systematic errors in detrital-corrected TM concentrations. Although weathering and fluvial transport can significantly reduce the variabilities of detrital TM/Ti ratios, the remaining variance is still significant and should be propagated into uncertainties in the corrected TM concentrations. [ABSTRACT FROM AUTHOR]

The progressively declining ecological condition of the Chesapeake Bay is attributed to the influx of contaminants associated with sediment loads supplied by its largest tributaries. The continued urban expansion in the suburbs of Virginia cities, modern agricultural activities in the Shenandoah Valley, the anthropogenic and climate driven changes in fluvial system hydrodynamics and their potential associated impacts on trace metals enrichment in the bay's tributaries necessitate constant environmental monitoring of these important water bodies. Eight 210 Pb and 137 Cs dated sediment cores and seventy two sediment grab samples were used to analyze the spatial and temporal distributions of Al, Ca, Mg, Cr, Cd, As, Se, Pb, Cu, Zn, Mn, and Fe in the waterways of the Virginia portion of the Chesapeake Bay basin. The sediment cores for trace metal historical fluctuation analysis were obtained in lower fluvial-estuarine environments and reservoirs in the upper reaches of the basin. The trace metal profiles revealed high basal enrichment factors (EF) of between 0.05 and 40.24, which are interpreted to represent early nineteenth century agricultural activity and primary resource extraction. Surficial enrichment factors on both cores and surface grab samples ranged from 0.01 (Cu) to 1421 (Cd), with Pb, Cu, Zn, and Cd enrichments a plausible consequence of modern urban expansion and industrial development along major transportation corridors. Contemporary surficial enrichments of As, Se, and Cr also ranged between 0 and 137, with the higher values likely influenced by lithological and atmospheric sources. Pearson correlation analyses suggest mining and agricultural legacies, coupled with aerosol deposition, are responsible for high metal concentrations in western lakes and headwater reaches of fluvial systems, while metal accumulation in estuarine reaches of the major rivers can be attributed to urban effluence and the remobilization of legacy sediments. [ABSTRACT FROM AUTHOR]

A synthesis of published vegetation mercury (Hg) data across 11 contiguous states in the western United States showed that aboveground biomass concentrations followed the order: leaves (26 μg kg − 1 ) ~ branches (26 μg kg − 1 ) > bark (16 μg kg − 1 ) > bole wood (1 μg kg − 1 ). No spatial trends of Hg in aboveground biomass distribution were detected, which likely is due to very sparse data coverage and different sampling protocols. Vegetation data are largely lacking for important functional vegetation types such as shrubs, herbaceous species, and grasses. Soil concentrations collected from the published literature were high in the western United States, with 12% of observations exceeding 100 μg kg − 1 , reflecting a bias toward investigations in Hg-enriched sites. In contrast, soil Hg concentrations from a randomly distributed data set (1911 sampling points; Smith et al., 2013a) averaged 24 μg kg − 1 (A-horizon) and 22 μg kg − 1 (C-horizon), and only 2.6% of data exceeded 100 μg kg − 1 . Soil Hg concentrations significantly differed among land covers, following the order: forested upland > planted/cultivated > herbaceous upland/shrubland > barren soils. Concentrations in forests were on average 2.5 times higher than in barren locations. Principal component analyses showed that soil Hg concentrations were not or weakly related to modeled dry and wet Hg deposition and proximity to mining, geothermal areas, and coal-fired power plants. Soil Hg distribution also was not closely related to other trace metals, but strongly associated with organic carbon, precipitation, canopy greenness, and foliar Hg pools of overlying vegetation. These patterns indicate that soil Hg concentrations are related to atmospheric deposition and reflect an overwhelming influence of plant productivity — driven by water availability — with productive landscapes showing high soil Hg accumulation and unproductive barren soils and shrublands showing low soil Hg values. Large expanses of low-productivity, arid ecosystems across the western U.S. result in some of the lowest soil Hg concentrations observed worldwide. [ABSTRACT FROM AUTHOR]

• An integrated acid-elutriation approach is developed for AD sludge post-treatment. • Dewaterability of AD sludge is significantly improved after acid-elutriation. • Optimal condition is identified as three rounds of elutriation on pH 2 sludge. • Acid-elutriation also greatly improves stabilization level and removes metals. This study aims to propose an optimum integrated strategy for recovery and carbon sink by simultaneously considering low-valued recyclables recycling and non-recyclables reduction in anaerobically digested (AD) sludge management. This is achieved based on the scienctific finding in this study that three rounds of acid-elutriation of the AD sludge (pH ≤ 2) effectively reduced the water content of the sludge filtration cake from 96.3 ± 0.8 to 73.6 ± 0.6 wt%, indicating an 86% reduction of sludge volume. The acid-elutriation also improved the stabilization of AD sludge in terms of specific oxygen uptake rate and pathogen level, which meets the criteria of Class-A Biosolids (United States Environment Protection Agency). The quality of dewatered sludge was enhanced with the reduction of >80% metals (including toxic B, Cr, Mn, Ni, Pb, and Zn). Fundamental investigations in this study illustrated a new mechanism underlying the observed substantial dewaterability improvements, i.e. acid-elutriation removes hydrophilic organic matter and leads to decreased repulsive force from hydration interaction energy. This novel mechanism suggests potential opportunities of combining other treatment technologies with elutriation, to achieve enhanced dewatering performance. [Display omitted] [ABSTRACT FROM AUTHOR]

The North Atlantic receives the highest aerosol (dust) input of all the oceanic basins. Dust deposition provides essential bioactive elements, as well as pollution-derived elements, to the surface ocean. The arid regions of North Africa are the predominant source of dust to the North Atlantic Ocean. In this study, we describe the elemental composition (Li, Na, Mg, Al, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Cd, Sn, Sb, Cs, Ba, La, Ce, Nd, Pb, Th, U) of the bulk aerosol from samples collected during the US-GEOTRACES North Atlantic Zonal Transect (2010/11) in order to highlight the differences between a Saharan dust end-member and the reported elemental composition of the upper continental crust (UCC), and the implications this has for identifying trace element enrichment in aerosols across the North Atlantic basin. As aerosol titanium (Ti) is less soluble than aerosol aluminum (Al), it is a more conservative tracer for lithogenic aerosols and trace element-to-Ti ratios. However, the presence of Ti-rich fine aerosols can confound the interpretation of elemental enrichments, making Al a more robust tracer of aerosol lithogenic material in this region. [ABSTRACT FROM AUTHOR]

High-resolution dissolved Fe (dFe) and dissolved Mn (dMn) distributions were obtained using a trace metal clean rosette during the GEOTRACES GA03 zonal transect cruises (USGT10 and USGT11) across the North Atlantic Ocean. This manuscript provides a general overview of the dFe, as well as dMn and dissolved Al (dAl) distributions that reveal several Fe inputs at varying depths across the study region. Elevated dFe concentrations correlate with elevated dAl concentrations in the surface waters of the subtropical gyre, indicating a significant atmospheric source of Fe, in contrast there is no apparent significant dust source for Mn. In the subsurface waters, dFe maxima are a result of the remineralization process, as revealed by their correspondence with dissolved oxygen minima. Within the oxygen minimum, the ratio of dFe to apparent oxygen utilization (AOU) is lower than would be expected from the measured Fe content of surface water phytoplankton, suggesting that a significant amount of dFe that is remineralized at depth (~63–90%) is subsequently scavenged from the water column. The rate of remineralization, which is based on the slope of dFe:AOU plot, is similar across a wide area of the North Atlantic. In addition to the remineralization process, sedimentary inputs are apparent from elevated dMn signals in the eastern basin, particularly near the African coast. In the western basin, sedimentary input is also occurring along the advective flow path of the Upper Labrador Sea Water (ULSW), as ULSW transits along the North American continental shelf region. The largest dFe anomaly (~68 nM), which also corresponds to a dMn anomaly (up to ~33 nM) is seen in the neutrally buoyant hydrothermal plume sampled over the Mid-Atlantic Ridge, and that signal is visible for ~500 km to the west of the ridge. [ABSTRACT FROM AUTHOR]

Understanding how metal concentrations in soil have responded to reductions of anthropogenic emissions is essential for predicting potential ecosystem impacts and evaluating the effectiveness of pollution control legislation. The objectives of this study were to present new data and synthesize existing literature to document decreases in Pb, Cu, and Zn concentrations in forest soils across the northeastern US. From measurements at 16 sites, we observed that forest floor Pb, Cu, and Zn concentrations have decreased between 1980 and 2011 at an overall mean rate of 1.3 ± 0.5% yr − 1 . E-folding times, a concentration exponential decay rate (1/ k ), for Pb, Cu and Zn at the 16 sites were estimated to be 46 ± 7, 76 ± 20 and 81 ± 19 yr, respectively. Mineral soil concentrations were correlated with forest floor concentrations for Pb, but not for Cu and Zn, suggesting an accumulation in one pool does not strongly influence accumulation in the other. Forest floor Pb, Cu and Zn concentrations from our sites and 17 other studies conducted from 1970–2014 in remote forests across the northeastern US were compiled into pooled data sets. Significant decreasing trends existed for pooled forest floor Pb, Cu, and Zn concentrations. The pooled forest floor Pb e-folding time was determined to be 33 ± 9 yrs, but the explanatory power of pooled Cu and Zn regressions were inadequate for calculating e-folding times ( r 2 < 0.25). Pooled Pb, Cu, and Zn concentrations in forest floor were multiple-regressed with latitude, longitude, elevation, and year of sampling, cumulatively explaining 55, 38, and 28% of the variation across compiled studies. Our study suggests anthropogenic Pb in the forest floor will continue to decrease, but decreases in forest floor Cu and Zn concentrations may be masked by spatial heterogeneity or are at a new steady state. [ABSTRACT FROM AUTHOR]

Lacustrine sedimentation and trace metal accumulation are naturally occurring processes that can be altered by anthropogenic activities. Indices of sediment or metal dynamics are important for the management and operational use of man-made reservoirs and their drainage basins. In this study, we compared two reservoirs in Virginia, USA, to quantify the effect of varying watershed characteristics on sediment and metal fluxes. Lake Pelham is a human-impacted reservoir surrounded by agricultural fields and anthropogenic developments, whereas Lake Moomaw is an undeveloped reservoir surrounded by moderate to extremely sloping forested landscapes. Three sediment cores were taken from each reservoir to estimate Pb-based sediment accumulation rates, organic matter content, and indices of trace metal enrichment and accumulation. The average Pb-based sediment accumulation rates were 0.348 ± 0.053 and 0.246 ± 0.043 g cm year for Lake Pelham and Lake Moomaw, respectively. The sediment trace metal results showed strong correlation with sediment organic content, and both reservoirs had moderate to high enrichment of Cu and little enrichment of Zn and Pb. Overall, Lake Moomaw had relatively low sediment accumulation and metal enrichment. Comparatively, Lake Pelham had significantly greater metal concentrations, which were highest in the upper reaches of the reservoir. Lake Pelham also had higher sediment accumulation rates and higher metal enrichment, reflecting the impact of human development within the greater watershed. Results from this study suggest that urbanization can increase reservoir sediment and metal fluxes, but atmospheric deposition is also important in forested watersheds that have not undergone anthropogenic land-use change. [ABSTRACT FROM AUTHOR]

Abandoned mining sites in hyperarid environments are generally assumed to present an insignificant risk to water availability. This study investigated the impact abandoned mine sites in Southern Nevada can have on the wider environment. Southern Nevada is characterized with little precipitation and prolonged droughts. Precipitation in Southern Nevada is often in the form of short and intense events with the potential to mobilize and transport contaminated sediments down gradient. This work evaluated the movement of trace elements (Ag, As, Ba, Cd, Cr, Hg, Pb, and Se) and cyanide in surface sediments of three desert washes near the historic mining town of Nelson, a hyperarid region of Southern Nevada. Results indicate trace elements have been mobilized and transported down gradient from sources to areas not directly impacted by mining. Contaminants used in mining operations (Hg and CN−) as well as those of geogenic nature migrated as far as 6000 m, providing evidence of their transport in hyperarid environments, contrary to the generally held belief. Although contaminants in this study are below levels that are environmentally significant, the findings show that transport is possible. This study demonstrates that large amounts of contaminant-laden sediments might be a significant threat in hyperarid environment and to areas down gradient from source materials. [ABSTRACT FROM AUTHOR]

The Mediterranean mussel Mytilus galloprovincialis (L.) was collected from the fall 2005 to the winter 2009 from the six sites on the Montenegrin coastline. Two wild samples were collected from the open sea coastline, and two cultivated and two wild were from the Boka Kotorska Bay. The mussels soft tissue was analyzed for zinc, copper, lead, cadmium, arsenic and total mercury. Concentrations of these metals, in mg kg-1 dry weight, ranged from 135-210 for Zn, 6.2-14.5 for Cu, 4.0-11.5 for Pb, 1.7-2.1 for Cd, 5.8-12.4 for As and 0.1-0.5 for Hg. The metals were found to be present in the samples at different levels, but not in concentrations higher than maximum residual levels prescribed by the European Union (EU) and US Food and Drug Administration (USFDA) regulations for seafood. This indicates that the consumption of wild or cultivated mussels from the studied area is safe in moderate quantities. [ABSTRACT FROM AUTHOR]

Concentrations of arsenic (As), selenium (Se), lead (Pb), zinc (Zn), cadmium (Cd), and total mercury (Hg) were analyzed in the muscle, liver, and gonads of the American monkfish, Lophius americanus, collected from Franklin Swell, Massachusetts; Mud Hole, New Jersey; and the Fingers, Maryland, in the northeastern US, by commercial gillnetters from February to May 2007. Results indicated that As and Hg concentrations were significantly higher in liver samples collected from the Fingers than from Mud Hole and Franklin Swell. The highest concentrations of Pb were found in muscle, liver, and gonads collected from Franklin Swell. L. americanus collected from the Fingers and Mud Hole had higher concentrations of Zn in the gonads and total Hg in the muscle than those collected from Franklin Swell. Significant differences were found in gonadal Cd concentrations among the three sites. A significant correlation was observed between hepatic Se and Hg molar concentrations in fish collected from Franklin Swell. The molar Se to Hg ratios were lowest in muscle and highest in gonads of L. americanus. With the exception of Hg, all metal concentrations were within the maximum permissible limit for human consumption. [ABSTRACT FROM AUTHOR]

The article presents a study on the combined application of quantitative evaluation of mineralogy by scanning electron microscope (QEM-SEM) and hard X-ray microscopy to determine mineralogical associations and chemical speciation of trace metals in the U.S. It notes the reliance of successful trace metal speciation in heterogeneous matrices on a combination of techniques including spectroscopy, microscopy and wet chemical and physical experiments. It highlights the detailed insights provided by the QEM-SEM with micro-focused X-ray diffraction into the composition of mineral assemblages and their effect on trace metal speciation.

We show that the oil sands industry releases the 13 elements considered priority pollutants (PPE) under the US Environmental Protection Agency's Clean Water Act, via air and water, to the Athabasca River and its watershed. In the 2008 snowpack, all PPE except selenium were greater near oil sands developments than at more remote sites. Bitumen upgraders and local oil sands development were sources of airborne emissions. Concentrations of mercury, nickel, and thallium in winter and all 13 PPE in summer were greater in tributaries with watersheds more disturbed by development than in less disturbed watersheds. In the Athabasca River during summer, concentrations of all PPE were greater near developed areas than upstream of development. At sites downstream of development and within the Athabasca Delta, concentrations of all PPE except beryllium and selenium remained greater than upstream of development. Concentrations of some PPE at one location in Lake Athabasca near Fort Chipewyan were also greater than concentration in the Athabasca River upstream of development. Canada's or Alberta's guidelines for the protection of aquatic life were exceeded for seven PPE-cadmium, copper, lead, mercury, nickel, silver, and zinc-in melted snow and/or water collected near or downstream of development. [ABSTRACT FROM AUTHOR]

The present study evaluated the use of the invasive clam Corbicula fluminea as a surrogate for metal accumulation in native mussels. The tissue concentrations of As, Cd, Cu, Hg, Mn, Ni, Pb, and Zn were analyzed in Corbicula and a native Unionid mussel species (Elliptio hopetonensis) collected from 13 sites in the Altamaha River system (GA, USA). Corbicula accumulated greater concentrations of As, Cd, Cu, Hg, and Ni when compared to E. hopetonensis at the same sites. The reverse was true for the metals Mn and Zn, with E. hopetonensis accumulating greater concentrations than Corbicula. Concentrations of As, Cd, Cu, Hg, and Pb were found to be significantly (α = 0.05) positively correlated between the two species. Greater water alkalinity and hardness tended to negatively correlate with metal accumulation, while organism size tended to correlate positively with tissue concentrations. Tissue Cd, Cu, and Pb concentrations demonstrated a correlation between bivalve tissues and concentrations of those metals in fine sediments. These correlations were significant (α = 0.05) for Cd and Cu concentrations in Corbicula and Pb concentrations in E. hopetonensis. The present findings support the hypothesis that bioaccumulation of some metals by Corbicula can be used to approximate levels accumulated by co-occurring native mussel species. Environ. Toxicol. Chem. 2010;29:2026–2033. © 2010 SETAC [ABSTRACT FROM AUTHOR]

Abstract: Lakes with complex morphologies and with different geologic and land-use characteristics in their sub-watersheds could have large differences in natural and anthropogenic chemical inputs to sub-basins in the lake. Lake Mead in southern Nevada and northern Arizona, USA, is one such lake. To assess variations in chemical histories from 1935 to 1998 for major sub-basins of Lake Mead, four sediment cores were taken from three different parts of the reservoir (two from Las Vegas Bay and one from the Overton Arm and Virgin Basin) and analyzed for major and trace elements, radionuclides, and organic compounds. As expected, anthropogenic contaminant inputs are greatest to Las Vegas Bay reflecting inputs from the Las Vegas urban area, although concentrations are low compared to sediment quality guidelines and to other USA lakes. One exception to this pattern was higher Hg in the Virgin Basin core. The Virgin Basin core is located in the main body of the lake (Colorado River channel) and is influenced by the hydrology of the Colorado River, which changed greatly with completion of Glen Canyon Dam upstream in 1963. Major and trace elements in the core show pronounced shifts in the early 1960s and, in many cases, gradually return to concentrations more typical of pre-1960s by the 1980s and 1990s, after the filling of Lake Powell. The Overton Arm is the sub-basin least effected by anthropogenic contaminant inputs but has a complex 137Cs profile with a series of large peaks and valleys over the middle of the core, possibly reflecting fallout from nuclear tests in the 1950s at the Nevada Test Site. The 137Cs profile suggests a much greater sedimentation rate during testing which we hypothesize results from greatly increased dust fall on the lake and Virgin and Muddy River watersheds. The severe drought in the southwestern USA during the 1950s might also have played a role in variations in sedimentation rate in all of the cores. [ABSTRACT FROM AUTHOR]

Abstract: Previous investigations suggest that contaminant transport from the large Kennebec/Androscoggin watershed is an important large-scale process in mid-coast Maine. To investigate this phenomenon, we determined the concentrations of Cd, Cr, Cu, Ni, Pb, Sn and Zn in the surface sediments of 47 stations in the tidal Kennebec/Androscoggin system. Most stations exhibited elevated metal concentrations. Highest levels were found in the main stem of the system. Distribution patterns lead to the conclusion that metals enter the system from the watershed and are transported to the nearshore Gulf of Maine. The coarse-grained, ebb tide dominated flow prevents the accumulation of contaminants in the estuary. This supports the hypothesis of that the Kennebec and Androscoggin watersheds are sources for contaminants observed in the nearshore Gulf of Maine. [ABSTRACT FROM AUTHOR]

Geochemical association plots are used as a screening tool for environmental site assessments and use empirical log–log relationships between total trace metal concentrations and concentrations of a major (i.e., reference) soil metal constituent, such as iron (Fe), to discern sites with naturally elevated trace metal levels from sites with anthropogenic contamination. Log–log relationships have been consistently observed between trace metal and reference metal concentrations and are often considered constant. Consequently, we used a regional geochemistry data set to evaluate background trace metal/Fe log–log associations across soils with highly diverse composition. Our results indicate that, although geochemical associations may be proportional, they significantly differ across predominant United States Department of Agriculture (USDA) soil orders. This suggests that highly complex interactions between soil-forming factors and variable secondary clay mineral composition affect the ratio of trace metals to Fe concentrations in soils. Also, intra-order variability in trace metal/Fe ratios generally ranged multiple orders of magnitude which suggest that the order level of the USDA soil taxonomic system is insufficient to reasonably classify background trace metal concentrations. Consequently, geochemical association plots are a useful screening tool for environmental site assessments, but ubiquitous application of generic background metal data sets could result in erroneous conclusions. Because significantly different ratios were observed across predominant USDA soil orders, an agglomerative clustering technique was used to elucidate hierarchical patterns of association. We present these results as a mechanism to aid environmental assessors in screening candidate background metal data sets for their applicability to site-specific soil composition; although site-specific background metal data should be utilized if ample pristine reference sites with similar (i.e., sub-order) soil composition can be identified and sampled. [ABSTRACT FROM AUTHOR]

Abstract: To investigate the chemical characteristics of precipitation in the polluted coastal atmosphere, a total of 46 event-based precipitation samples were collected using a wet-only automatic precipitation collector from September 2006 to October 2007 at metropolitan Newark, New Jersey in the US East Coast. Samples were analyzed by ion chromatography for the concentrations of major inorganic ions (Cl−, NO3 −, SO4 2−, F−, NH4 +, Ca2+, Mg2+, Na+, K+) and organic acid species (CH3COO−, HCOO−, CH2(COO)2 2−, C2O4 2−). Selected trace metals (Sb, Pb, Al, V, Fe, Cr, Co, Ni, Cu, Zn, Cd) in samples were determined by ICPMS. Mass concentration results show that SO4 2− was the most dominant anion accounting for 51% of the total anions, controlling the acidity of the precipitation. NH4 + accounted for 48.6% of the total cations, dominating the precipitation neutralization. CH3COO− and HCOO− were the two dominant water-soluble organic acid species, accounting for 42% and 40% of the total organic acids analyzed, respectively. Al, Zn and Fe were the three major trace metals in precipitation, accounting for 34%, 27%, and 25% of the total mass of metals analyzed. The pH values in precipitation ranged from 4.4 to 4.9, indicating an acidic nature. Enrichment Factor (EF) Analysis showed that Na+, Cl−, Mg2+ and K+ in the precipitation were primarily of marine origin, while most of the Fe, Co and Al were from crust sources. Pb, V, Cr, Ni were moderately enriched with EFs ranging 43–410, while Zn, Sb, Cu, Cd and F− were highly enriched with EFs > 700, indicating significant anthropogenic influences. Factor analysis suggests 6 major sources contributing to the observed composition of precipitation at this location: (1) nitrogen-enriched soil, (2) secondary pollution processes, (3) marine sources, (4) incinerations, (5) oil combustions, and (6) malonate–vanadium enriched sources. To further explore the source–precipitation event relationships and seasonality, cluster analysis was performed for all precipitation events. Results show that about half of the precipitation events were characterized by mixed sources. Significant influences of nitrogen-enriched soil and marine sources were associated with precipitation events in spring and autumn, while secondary pollution processes, incineration and oil combustion contributed greatly in summer. [Copyright &y& Elsevier]

The influences of coal-mine hollow fills and associated settling ponds in three headwater streams were assessed in southern West Virginia, USA. Fill drainage waters had elevated conductivities and metal concentrations, compared to a regional reference. Benthic macroinvertebrate richness was not affected consistently by the hollow fill drainages, relative to a regional reference, although a more tolerant community, lacking in Ephemeroptera taxa at most locations, was evident. Collector-filterer populations were elevated at monitoring stations directly below the settling ponds, indicating that the ponds’ presence influenced macroinvertebrate community structure by means of organic enrichment. Corbicula fluminea growth was enhanced in monitoring locations directly below the settling ponds, also an apparent result of organic enrichment. Results of acute water column toxicity testing with Ceriodaphnia dubia, sediment chronic toxicity testing with Daphnia magna, and in-situ ecotoxicological assessments with C. fluminea demonstrated no mortality or toxic influence at most of the sites tested below the ponds. The settling ponds appear to serve as sinks in collecting some, but not all, trace metals. [ABSTRACT FROM AUTHOR]

Abstract: Surface transects and vertical profiles of macronutrients, dissolved iron (D-Fe), and dissolved manganese (D-Mn) were investigated during August 2003 in the southeastern Bering Sea. We observed iron-limited, HNLC surface waters in the deep basin of the Bering Sea (15–20μmol/kg nitrate, ∼0.07nmol/kg D-Fe, and ⩽1.0nmol/kg D-Mn); nitrate-limited, iron-replete surface waters over the shelf (<0.1μmol/kg nitrate, 0.5–4nmol/kg D-Fe, and 2–33nmol/kg D-Mn); and high biomass at the shelf break (“Green Belt”), where diatoms appeared to have been stressed by low D-Fe concentrations (<0.3nmol/kg). Sources of nitrate and iron to the Green Belt were investigated. A mixture of Aleutian North Slope Current water (with elevated, but non-sufficient iron concentrations relative to its high nitrate concentrations) and surface waters from the vicinity of the Bering Canyon (with lower nitrate concentrations, but similar dissolved iron concentrations) was carried along the shelf break by the Bering Slope Current. This water mixture provided macro- and micronutrients at the southern end of the shelf break. The oceanic domain supplied additional macronutrients to Green Belt waters, while the bottom layer of the outer shelf domain supplied additional macro- and micronutrients through enhanced vertical mixing at the shelf break. Surface waters near the Pribilof Islands, where the highest surface D-Fe concentrations were observed (∼5–6nmol/kg), represent a potential source of additional iron to Green Belt waters. During summer, the subsurface water of the middle shelf domain is a potential source of nitrate to the nitrate depleted waters of the shelf. In this subsurface cool pool, we observed evidence of substantial denitrification with lower than expected nitrate concentrations. [Copyright &y& Elsevier]

The article examines diatoms, pollen, total organic carbon, total nitrogen, stable isotopes, total phosphorus, biogenic silica and trace metals in intertidal sediments and established a chronology with radiocarbon, 210pb and indicator pollen horizons to document the natural baseline conditions and investigate the recovery of a severely degraded river-estuary complex in mid-coast Maine. The objectives of the study were to determine baseline conditions associated with natural climatic variability, investigate the effects of European settlement and industrialization within the watershed and examine ecosystem response to environmental regulation in the late 20th century.

Although legislation in the late 1970s significantly reduced atmospheric lead (Pb) inputs to ecosystems in North America, organic (O) horizons in forests of the northeastern USA still contain up to 30 kg of gasoline-derived Pb ha-1. The residence time, geochemical behavior, and fate of this contaminant Pb in soils is poorly understood. Here we use forest floor time series data and synchrotron-based X-ray techniques to examine the mobility and speciation of Pb in O horizons collected from remote sites across the northeastern USA. At high elevation (>800 m) sites in Vermont and New York, samples collected from similar locations in 1980, 1990, and early 2000 had indistinguishable Pb contents, ranging (±1σ) from 11 to 29 kg Pb ha-1. However, at lower elevation and lower latitude sites with mixed vegetation, significant decreases in Pb amount were observed during the two-decade study period. Lower elevation sites ranged from 10 to 20 kg Pb ha-1 in 1980, and from 2 to 10 kg Pb ha-1 20 yr later. Lead-enriched soil grains were determined to be amorphous with microfocused X-ray diffraction, and Pb concentrations correlated well with Fe on maps generated via microfocused X-ray fluorescence. Bulk Pb LIII-edge X-ray absorption spectroscopy of coniferous O horizon samples indicate that Pb is binding to iron-rich soil particles by inner-sphere complexes, most likely to amorphous Fe oxides. Based on our paired regional and microscopic observations, we conclude that Pb is strongly retained in well-drained O horizons, and mobility is governed by decomposition and colloidal transport. [ABSTRACT FROM AUTHOR]

This article focuses on the recovery and distribution of biosolids-derived trace metals in a clay loam soil. Land application of biosolids increases metal concentrations in soils. The U.S. Environmental Protection Agency (EPA) developed a risk assessment method to evaluate the potential negative effects of pollutants in biosolids. The U.S. EPA 40 CFR Part 503 was promulgated as the Standards for the Use and Disposal of Sewage Sludge. The Part 503 rule permits long-term application of biosolids to agricultural land with the assumption that the soil accumulation of trace metals from biosolids meeting ceiling concentrations will not cause environmental or health hazards during or after the application period. The concept of long-term metal immobilization in soil has been challenged when mass balance calculations at a number of land application studies were unable to account for up to ha! of biosolids-applied trace metal.

The forest floor at high elevation spruce-fir sites from southern Vermont, U.S. to the Gaspé Peninsula, Québec, Canada was sampled and analyzed in 1979 and re-sampled and analyzed in 1996 to study temporal changes in the impacts of atmospheric pollutants. We determined organic matter mass, pH, and concentrations of Al, Ca, Fe, K, Mg, Na, Cd, Cu, Hg, Pb, and Zn for the litter (L = fresh litter plus Oi horizon) and fermentation plus humic horizons (F+H) (= Oe plus Oa horizons) of the forest floor. There were no trends for Al or Fe concentrations in the 1979 or 1996 L along the transect. Several sites had significantly lower Al and Fe values in 1996 than in 1979, likely indicating less mineral soil in the 1996 samples. The 1996 concentrations of Ca in L increased along the transect from 0.22% dry weight (dw) in Vermont to 0.60% dw in Québec. Concentrations of Mg in L were relatively constant along the transect. Neither Ca nor Mg changed at sites from 1979 to 1996, indicating unchanged base status. Concentrations of Cd did not vary spatially along the transect but decreased at all sites from 1979 to 1996. Cu and Zn did not vary spatially or with time. In 1979, the concentration of Hg in L ranged between 150 and 300 μg kg−1 dw, with no spatial gradient. By 1996, Hg concentrations were 25 to 50% lower in L, with decreases generally proportional to the concentration in 1979. The concentration of Pb in 1979 L decreased significantly from 200 mg kg−1 dw in southern Vermont to 60 mg kg−1 dw in Québec. By 1996, the Pb concentration in L ranged between 32 and 66 mg kg−1 dw with no spatial trend along the transect. Decreases in Pb concentrations at sites were proportional to the absolute value in 1979. The concentrations of Cd, Hg, and Pb have declined in litter from 1979 to 1996, indicating a decline in atmospheric deposition. Higher Hg and Pb accumulation rates to the southwest are suggested for the past as indicated by (F+H) concentrations and inventories of Hg and Pb. The decline of Pb in L is consistent with the decreased use of leaded gasoline starting in the 1970s; the declines in Cd and Hg probably reflect lower emissions over the same period. Declining concentrations of Cd, Hg, and Pb in L parallel those documented in recent lake and peat sediments in the northeastern United States. [ABSTRACT FROM AUTHOR]

Two hundred seventeen tap water samples, from homes in 26 counties of eastern Kentucky, western West Virginia, southeastern Ohio, and northeastern Tennessee, USA, were analyzed for arsenic (As) by Hydride Generation AAS. Nearly half of the 179 samples from private wells had detectable arsenic, and, of these, 43% had 0.5-1.0 ppb, 34%, 1.1-3.0 ppb, 6%, 3.1-5.0 ppb, 11%, 5.1-10.0 ppb, and 6% had As far exceeding the new Maximum Contamination Level (MCL) of 10 ppb recently set by the U.S. Environmental Protection Agency (USEPA). Based on the National Research Council’s 2001 report to the USEPA, the lifetime risk of bladder and lung cancer from water arsenic exposure at 10 ppb is about one in 333 individuals, which is much higher than the standard of one in 10,000 individuals set for other carcinogens. Even at 5 ppb, the risk is 1 in 667, at 3 ppb, 1 in 1000, and at 1 ppb, 1 in 3100. The incidence of arsenic-related cancers and other diseases in this coal-mining region is high, and 57% of the well water samples tested in this study had levels over 1 ppb As. Since Central Appalachian families rely heavily on private wells, and the U.S. Federal 2006 compliance edict does not apply to private water sources, more extensive sampling and analysis of well water in the region, using the most sensitive methodology available, is recommended. A public awareness campaign and routine health screening for arsenic exposure is also recommended. [ABSTRACT FROM AUTHOR]

Abandoned mines are known to contaminate private drinking water wells with toxic metals and arsenic (As). Little attention is given, however, to sites in rural areas with low population densities where natural, geogenic sources of contaminants might also occur. This study measured arsenic and trace element exposure among residents consuming water from wells adjacent to abandoned mines near Twisp, in Okanogan County, Washington, USA, estimated the risk of adverse health effects, and considered the degree of uncertainty associated with the assessed risk. Water samples were collected between October 1999 and June 2001. Average As concentrations ranged from <1 to 298 µg L-1, lead (Pb) ranged from 0 to 94 µg L-1, cadmium (Cd) 0–5 µg L-1, and selenium (Se) 0–390 µg L-1. Concentrations varied seasonally with maximum concentrations occurring in conjunction with snow-melt. The calculated risk of mortality from cancer following exposure to As at average concentrations as low as 8 µg L-1 was greater than one in 10,000. Additional noncarcinogenic risks are associated with exposure to As, Cd, Pb and Se. A potentially affected population, estimated to be between 1000 and 1287 residents, live within a 6.5-km (4-mile) radius of the study site. This study emphasises the need to test drinking water wells in the vicinity of abandoned mines during times of maximum snow-melt to determine the extent of risk to human health. Residents drinking water from wells tested in this study who want to reduce the estimated carcinogenic risk and the noncarcinogenic hazard quotient should consider treating their water or find alternative sources. [ABSTRACT FROM AUTHOR]

Concentration and distribution of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead(Pb), and zinc (Zn) were determined in 26 soil profiles (n = 78) of northern Kentucky in response to environmental concerns about increasing anthropogenic inputs in a fast-paced urbanizing area. The selected sites represent alluvial, glacial till or residual soils that have not received any biosolid- or industrial-waste applications. Mean concentrations of Zn (53.8 mg kg-1)and Ni (25.9 mg kg-1) were the highest in the soil profile, whereas Cd (0.21 mg kg-1)was present only in trace amounts. All metals were within the low to middle range of baseline concentration reported for US soils, suggest-ing minimal anthropogenic inputs. The distribution of Cu, Cr, Ni, and Zn increased with soil depth, whereas Cd and Pb concentrations were unaffected throughout the soil profile. Alluvial soils had the highest overall metal accumulations, particularly in surface soil horizons, indicating potential metal enrichment through deposition processes. The presence of a fragipan horizon or depth to bedrock did not significantly affect metal retention. Single correlation and multiple regression analyses indicated OM and pH as the most influential soil parameters for metal retention, followed by cation exchange capacity (CEC) and CEC/clay. Single correlations among metals suggested strong covariance of Zn with most metals throughout the soil profile, but weaker for Pb and Ni. [ABSTRACT FROM AUTHOR]

The concentrations of trace elements in water, sediment and fish samples from Tuskegee Lake located in Southeastern United States were investigated in this study. The Lake is utilized both as a source for municipal drinking water, and for recreational fishing. The water quality characteristics over two sampling periods, the speciation of metals in the Lake sediments, the risk to water column contamination and levels of heavy metals in largemouth bass (Micropterus salmoides) samples from the Lake were evaluated. The Lake water quality characteristics were mostly below the recommended drinking water standards by the United States Environmental Protection Agency (US EPA) and the European Union (EU) except for aluminum, iron, manganese and thallium. In addition, the average values of Cr, As, Mn, Zn and Cl- in the water samples analyzed were higher than the respective reference values for fresh water. To study the speciation of metals in the Lake sediments, ten elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn) in four grain sizes (< 710 μm – 250 μm, < 250 μm – 75 μm, < 75 μm – 53μm, and < 53 μm) were subjected to sequential extractions. Irrespective of grain size, the elements analyzed were distributed in both the non-residual and residual phases except Ni that was found only in the residual fraction. The potential risk to Lake water contamination was highest downstream (Sites 1 and 2) based on the calculated global contamination factors. From the calculated individual contamination factors, Mn and Pb followed by Zn, Cu, Cr, Co and V posed the highest risk to water contamination. Based on this study, the human health risks for heavy metals in fish caught from Tuskegee Lake are low for now, and irrespective of the source of fish, concentrations of metals in muscle tissues were all below the recommended Food and Agriculture Organization (FAO) maximum limits for Pb (0.5 mg Kg-1), Cd (0.5 mg Kg-1), Cu (30 mg Kg-1), and Zn (30 mg Kg-1) in fish. [ABSTRACT FROM AUTHOR]

Contaminant inputs from wastewater discharge, a major source of contamination to Santa Monica Bay (SMB), have declined drastically during the last three decades as a result of improved treatment processes and better source control. To assess the concomitant temporal changes in the SMB sediments, a study was initiated in June 1997, in which 25 box cores were collected using a stratified random sampling design. Five sediment strata corresponding to the time intervals of 1890–1920, 1932–1963, 1965–1979, 1979–1989, and 1989–1997 were identified using 210Pb dating techniques. Samples from each stratum were analyzed for metals, 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites (DDTs), polychlorinated biphenyls (PCBs), and total organic carbon (TOC). Samples from the 1965–1979, 1979–1989, and 1989–1997 strata were also analyzed for polycyclic aromatic hydrocarbons (PAHs) and linear alkylbenzenes (LABs). Sediment metal concentrations increased from 1890–1979 and were similar during the time intervals of 1965–1979, 1979–1989, and 1989–1997, although the mass emissions of trace metals from sewage inputs declined substantially during the same time period. Trace organic contamination in SMB was generally highest in sediments corresponding to deposition during the years of 1965–1979 or 1979–1989 and showed a decline in concentration in the 1989–1997 stratum. Temporal trends of contamination were greatest in sediments collected from areas near the Hyperion Treatment Plant (HTP) outfall system and on the slope of Redondo Canyon. The highest contaminant concentrations were present in sediments near the HTP 7-mile outfall in the 1965–1979 stratum. Elevated trace metal and organic concentrations were still present in the 1989–1997 stratum of most stations, suggesting that sediment contaminants have moved vertically in the sediment column since sludge discharges from the 7-mile outfall (a dominant source of contamination to the bay) ceased in 1987. The widespread distributions of DDTs and PCBs in SMB and highly confined distribution of LABs around the HTP outfall system were indicative of a dispersal mechanism remobilizing historically deposited contaminants to areas relatively remote from the point of discharge. [Copyright &y& Elsevier]

The effects of shrimp trawling on sediment oxygen consumption and the sediment–water exchange fluxes of nutrients (ammonium, phosphate and silicate) and trace metals (Mn, Ni, Cu, Cd and Pb) were determined for two separate experiments conducted during July 1998 and May 1999. Oxygen microelectrode measurements showed that during the 1998 experiment, the surface sediments were oxic down to depths of approximately 15 mm suggesting that the study area had not been recently trawled. However, after passage of the trawl gear oxygen was present to depths of only 5 mm. This suggests resuspension of the upper 1 cm of sediment and resulted in ammonium and manganese fluxes increasing by a factor of 2–3, which was attributed to a similar mechanism, i.e. a strengthening of the diffusive gradient. The measured fluxes of oxygen, phosphate and the trace metals Ni, Cu and Pb were not affected by trawling, while the flux of Cd was affected.During the 1999 shrimp trawl experiment, pre- and post-trawl oxygen penetration was limited to the upper 1 mm of sediment suggesting the area had been recently trawled. The diffusive fluxes of oxygen were in agreement with directly measured oxygen fluxes, both prior to and after trawling; further indication that trawling had little to no effect on the exchange of oxygen across the sediment–water interface during this time. Macrofaunal abundance was significantly reduced during 1999 and consistent with sediment oxygen consumption rates, which were also lower during this time. This resulted in the fluxes of oxygen, which were enhanced by biological processes during 1998, becoming diffusion controlled during 1999. This resulted in pre- and post-trawl fluxes of oxygen, ammonium, silicate, Mn, Ni, Cu and Pb, when considering the measurement error, which did not differ significantly. Cd again seemed affected by shrimp trawling activities.An increase or decrease in a trace metal''s turnover time (the time in days required to replenish the water column concentration) can have important implications towards the overall health of an estuary. In Galveston Bay, trace metal turnover times averaged 0.4±0.5, 52±32, 27±15, 22±23 and 5.3±3.0 d for Mn, Ni, Cu, Cd and Pb, respectively. These relatively short turnover times indicate that the sediments can be an important source of trace metals to the overlying water column, especially during low-flow periods of the Trinity River, which can sometimes last more than 1 yr. This, in turn, could possibly lead to the non-conservative mixing behaviors, for both nutrients and trace metals, previously reported for the Trinity Bay region of Galveston Bay, as conservative mixing is observed in the lower estuary.Our study shows that the effects of shrimp trawling are largely dependent on the prevailing sediment redox conditions due to the shallow penetration depth of both oxygen and the trawl gear. Therefore, it is unlikely that trawling activities adversely affect the overall health of Galveston Bay. However, repeated trawling with removal of the upper oxic sediment layers could trend surface sediments towards anoxia and ultimately lead to changes in benthic–pelagic coupling. [Copyright &y& Elsevier]

Sequential chemical extraction (SCE) and quantitative X-ray diffraction (QXRD) were used in combination to assess trace metal speciation and availability in sediment from two separate marshes in western Vermont, USA, one with high (45%) and one with low (<5%) northern leopard frog (Rana pipiens) malformity rates. The types of malformities observed in the field are very similar to malformities produced in laboratory studies where frogs are exposed to waters and sediments with elevated levels of trace metals such as Co, Cu, Ni, and Zn.Total recoverable metals, as determined by US EPA method 200.2 (HCl–HNO3), are statistically higher in the malformity-affected marsh than in the marsh with low malformity rates, suggesting possible causality. Analysis of trace metal speciation by SCE and QXRD, however, implies that the most common reservoir of Co, Cr, Cu, Ni, and Zn in the sediment is trioctahedral clay minerals, including chlorite, high charge smectite and vermiculite. The only trace metal that is not associated with trioctahedral clay is Pb, which appears to be contained in poorly crystalline or amorphous oxyhydroxides. The proportions of trace metals in the exchangeable fraction are variable, with values of ≤3% of total Cr and Pb, 2–17% of total Cu and Ni, and up to 24% of total Co and Zn. Total metals concentrations may be slightly elevated relative to background values, and the partitioning of Co, Cu, Ni, and Zn into the exchangeable fraction implies a mechanism for interaction with frogs. Furthermore, partitioning of Pb into poorly crystalline or amorphous oxyhydroxides suggests that it might be mobilized when water levels rise and cause reduction and dissolution of oxyhydroxides in submerged sediment. The difference in speciation between Pb on the one hand, and Co, Cr, Cu, Ni, and Zn on the other, implies that only Pb has an anthropogenic source. Mn speciation differs from all other metals in that it is subequally partitioned into exchange sites, hydroxides and trioctahedral clay. Fe is predominantly partitioned into trioctahedral clay, with lesser amounts in hydroxide form.QXRD indicates that expandable trioctahedral clay dissolves progressively throughout the SCE procedure, including during extractions intended to (1) oxidize sulfides and organic matter, and (2) reduce oxides and hydroxides, indicating that SCE procedures are not entirely phase selective. It also underscores the need for quantitative mineralogical analysis in conjunction with SCE, and has important implications for the interpretation of metal speciation by SCE alone and without corroborating QXRD analyses. [Copyright &y& Elsevier]

Zinc, major ion, and other trace metal (V, Cr, Co, Ni, Cu, Cd, and Pb) concentrations were measured within 172 street and stream runoff samples in the Atlanta metropolitan region and in relatively undeveloped watersheds within the Georgia Piedmont and Blue Ridge Provinces. Peachtree Creek, draining a densely populated area of Atlanta, was the primary sampling location and samples were acquired under a wide range of hydrological conditions. Zinc concentrations within street runoff [median (Zn)urban street runoff=905 µg/l] were significantly greater than zinc concentrations within storm runoff [median (Zn)Peachtree Creek=60 µg/l], which were, in turn, greater than zinc concentrations within non-storm runoff [median (Zn)Peachtree Creek=14 µg/l]. Zinc concentrations were not significantly greater within urban base flow than within non-urban base flow, indicating that the primary source of pollution is "event water" or street runoff. Zinc was the only heavy metal present in greater than "background" concentrations (i.e., >10 µg/l), which is likely the result of automotive pollution that is omnipresent within the study area. Analysis of storm alkalinity dilution trends indicate that simple mixing between polluted street runoff and groundwater cannot account for the zinc concentrations observed within storm and recession flows. A two end member mass balance model suggests that a large proportion of the zinc present in the street runoff is adsorbed and transported on surfaces of the suspended sediment. Adsorption is readily possible at the near neutral pH (~6.5) of turbid storm discharge. [ABSTRACT FROM AUTHOR]

Aluminum is often used as a conservative tracer to separate natural from anthropogenic components of metal contamination in marine sediments, but identifying uncontaminated sites to develop baseline metal:aluminum relationships can be problematic in populated areas. Here we present a new method for identifying baseline relationships in high population density areas. The method involves comparing the residual from the metal:aluminum regression with an independent estimate of laboratory measurement error, based on the premise that mean square error from the regression must equal laboratory measurement error for any data set that is free of anthropogenically enriched sites. The method is applied to data sets from the mid-Atlantic and Gulf coasts of the United States to test consistency in baseline relationships between these two coasts of geologically different origin. Differences in metal:aluminum relationships between coasts were found to be small and limited to the least abundant trace metals. [ABSTRACT FROM AUTHOR]

This Florida Geological Survey U.S. Department of the Interior, Minerals Manage ment Service Cooperative Study provides baseline data for major and trace metal concentrations in the sediments of the Steinhatchee River estuary. These data are intended to provide a benchmark for comparison with future metal concentration data measurements. The Steinhatchee River estuary is a relatively pristine bay located within the Big Bend Wildlife Management Area on the North Central Florida Gulf of Mexico coastline. The river flows 55 km through woodlands and planted pines before emptying into the Gulf at Deadman Harbor. Water quality in the estuary is excellent at present. There is minimal development within the watershed. The estuary is part of an extensive system of marshes that formed along the Florida Gulf coast during the Holocene marine transgression. Sediment accretion rate measurements range from 1.4 to 4.1 mm yr on the basis of lead-210 measurements. Seventy-nine short cores were collected from 66 sample locations, representing four lithofacies: clay- and organic-rich sands, organic-rich sands, clean quartz sands, and oyster bioherms. Samples were analyzed for texture, total organic matter, total carbon, total nitrogen, clay mineralogy, and major and trace-metal content. Follow ing these analyses, metal concentrations were normalized against geochemical reference elements (aluminum and iron) and against total weight percent organic matter. Metals were also normalized granulometrically against total weight percent fines (0.062 mm). Concentrations were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) for all metals except mercury. Mercury concentrations were determined by cold-flameless atomic absorption spectrometry (AAS). Granulo metric measurements were made by sieve and pipette analyses. Organic matter was determined by two methods: weight loss upon ignition and elemental analysis (by Carlo-Erba Furnace) of carbon and nitrogen. X-ray diffraction was used to deter mine clay mineralogy. Trace-metal concentrations were best correlated when normalized with respect to sediment aluminum concentrations. Normalizations indicate that most major and trace-metal concentrations fall within 95 % prediction limits of the expected value. This finding suggests that little significant metal contamination occurred within this system prior to 1994 sediment sampling. Exceptions include lead, mercury, copper, zinc, potassium, and phosphorous. Lead and mercury are elements that generally enter this watershed through atmospheric deposition; thus, anomalous levels of these metals are not necessarily associated with activities within the watershed of the Steinhatchee River estuary. Anomalous concentrations of other metals such as zinc, copper, and phosphorous probably do originate within the Steinhatchee watershed. Copper failed to correlate well with any geochemical or granulometric normalizer, and this condition was not limited to a single facies or area within the estuary. This finding may indicate copper contamination in the system. Increased zinc and copper levels may be attributed to marine paints. Phosphorous levels also appeared to be elevated in a few locations in the two marsh facies sampled. This may be due to nutrient loading from two small communities, Jena and Steinhatchee, or from the application of this element in fertilizer to reduce moisture stress to young planted pines on tree farms within the watershed. [ABSTRACT FROM AUTHOR]

Microbialites undergo a well – documented resurgence following the Permian – Triassic mass extinction. This comeback has been attributed to several causes, including the emptying of Early Triassic ecosystems by the severity of the extinction, a decline in burrowing activity and intensity, and the unusual chemistry of Early Triassic oceans. A laterally – continuous stromatolite horizon found within the Lower Triassic Virgin Limestone was examined at the Blue Diamond, NV U.S.A. locality in order to determine the factors that led to growth of the stromatolites, and by extension, the environmental conditions that led to the formation of widespread microbialites in the aftermath of the Permian-Triassic mass extinction. The Virgin Limestone at the study locality consists of ~6 m – thick cycles of shale and siltstone that pass upwards into bioturbated lime mudstone, and are capped by oolitic packstone or grainstone. Each ~6 m – thick cycle represents a rapid sea level rise that led to the deposition of fine – grained clastics below storm wave base, followed by deposition of coarsening – upwards carbonates that were deposited in progressively shallower environments. Analysis of redox-sensitive trace metals (U. V and Mo) from the shale and siltstone interbeds indicate that the fine – grained clastics were deposited under dysoxic waters, however, extensive bioturbation and macrofossils from the carbonate units indicates better aeration of shallower settings. The stromatolites occur within a single, laterally extensive horizon, and 4 distinct stromatolite morphologies are observed along a 3 km long transect, including: 1) aggregates of high-relief hemispherical domes and columnar stromatolites with well-developed laminae that are up to 0.75 m thick; 2) lozenge-shaped aggregates of intergrown columnar stromatolites with dimpled top surfaces; 3) isolated hemispheroids; and, 4) meandering ridges of intergrown domes that are small, low – relief (usually <7 cm), and have a clotted fabric. Isolated hemispheroids are found across the entire study area, while the large hemispherical and columnar aggregates, lozenge-shaped masses and the small intergrown domes are found in the southern, central and northern portion of the study area, respectively. Analysis of trace metals from shale directly underlying the stromatolites reveals an intensification of dysoxic conditions that may have initiated mound growth, while the occurrence of distinct burrows and a sparse fauna within the stromatolites indicates at least partially – oxygenated conditions as the stromatolites developed on the seafloor. Overall, stromatolite growth was controlled by a combination rapid calcification of the mounds related to the unusual carbonate chemistry of Early Triassic oceans, a microbial bloom driven by N – fixing diazotropic cyanobacteria, and possibly intermittent dysoxic conditions that limited grazing metazoans. Comparison of Lower Triassic stromatolites from the Blue Diamond locality to others from the western United States reveals the importance of localized conditions in initiating microbialite growth and determining the complexity of microbialite ecosystems. • Analysis of shale units reveals that dysoxic waters periodically encroached into middle to shallow shelf settings during the Early Triassic. • Variation in size, morphology and density was controlled by enhanced calcification, nutrient availability and transient dysoxia. • Initial development of the stromatolites was likely the result of dysoxic conditions, but the stromatolites grew under generally oxic conditions. • Stromatolites can be considered to be evidence of environmental stress, but should not be attributed to dysoxia without analysis of surrounding facies. [ABSTRACT FROM AUTHOR]

Wildland firefighters are repeatedly exposed to elevated levels of wildland fire smoke (WFS) while protecting lives and properties from wildland fires. Studies reporting personal exposure concentrations of air pollutants in WFS during fire suppression or prescribed burn activities have been geographically limited to the western and southeastern United States. The objective of this study is to characterize exposure concentrations of air pollutants in WFS emissions among wildland firefighters who conducted prescribed burns in the Midwest. Between 2016 and 2019, a total of 35 firefighters (31 males and 4 females, age of 35.63 ± 9.31 years) were recruited to participate in this study. Personal particulate matter 2.5 (PM 2.5) and carbon monoxide (CO) exposure concentrations were measured during prescribed burns. The level of black carbon (BC) in WFS particulates was determined using the light transmission technique, while trace metal composition was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The results showed geometric means for PM 2.5 , CO, and BC concentrations were 1.43 ± 0.13 mg/m3, 7.02 ± 0.69 ppm, and 58.79 ± 5.46 μg/m3, respectively. Although no occupational exposure limits (OELs) were exceeded by 8-h time-weighted average (TWA) exposure concentration observed in the firefighters, a total of 28 personal CO exposure concentrations were above the National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) Ceiling (200 ppm) for CO. PM 2.5 and CO concentrations were about 2–7 times higher in the Midwest than the other regions. Firefighters who performed holding had higher CO exposure concentrations compared to firefighters who performed lighting (p < 0.01), while lighters were exposed to higher level of BC in the smoke particulates (p < 0.01), possibly due to the domination of exposure by different combustion sources and stages. The levels of trace metals in WFS particulates were well below the corresponding OELs and no task-related difference was observed except for manganese. Our results suggest that wildland firefighters in the midwestern region have higher WFS exposures while working at prescribed burns compared to those western and southeastern United States. • Firefighters were exposed to elevated levels of WFS during prescribed burns. • PM 2.5 and CO exposure was 2–7 times higher in Midwest than in other regions. • Task-related difference in exposure concentrations was observed. • Firefighters who engaged in holding had a higher PM 2.5 and CO exposure level. • Lighting firefighters were exposed to the highest level of BC in WFS particulates. [ABSTRACT FROM AUTHOR]