Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Water, Air, & Soil Pollution”

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 127 records · Page 7Linked to original sources
USGS2001

Fulvic acid-sulfide ion competition for mercury ion binding in the Florida everglades

Negatively charged functional groups of fulvic acid compete with inorganic sulfide ion for mercury ion binding. This competition is evaluated here by using a discrete site-electrostatic model to calculate mercury solution speciation in the presence of fulvic acid. Model calculated species distributions are used to estimate a mercury-fulvic acid apparent binding constant to quantify fulvic acid and sulfide ion competition for dissolved inorganic mercury (Hg(II)) ion binding. Speciation calculations done with PHREEQC, modified to use the estimated mercury-fulvic acid apparent binding constant, suggest that mercury-fulvic acid and mercury-sulfide complex concentrations are equivalent for very low sulfide ion concentrations (about 10-11 M) in Everglades' surface water. Where measurable total sulfide concentration (about 10-7 M or greater) is present in Everglades' surface water, mercury-sulfide complexes should dominate dissolved inorganic mercury solution speciation. In the absence of sulfide ion (for example, in oxygenated Everglades' surface water), fulvic acid binding should dominate Everglades' dissolved inorganic mercury speciation.

Florida↗
USGS2001

Copper, cadmium, and zinc concentrations in juvenile Chinook salmon and selected fish-forage organisms (aquatic insects) in the upper Sacramento River, California

This study assessed the downstream extent andseverity of copper (Cu), cadmium (Cd), and zinc (Zn)contamination from acid mine drainage on juvenile chinook salmon( Oncorhynchus tshawytscha ) and aquatic insects over aroughly 270-km reach of the Sacramento River below KeswickReservoir. During April–May 1998, salmon were collected fromfour sites in the river and from a fish hatchery that receiveswater from Battle Creek. Salmon from river sites were examinedfor gut contents to document their consumption of variousinvertebrate taxa, whereas salmon from river sites and thehatchery were used for metal determinations. Midge(Chironomidae) and caddisfly (Trichoptera) larvae and mayfly(Ephemeroptera) nymphs were collected for metal determinationsduring April–June from river sites and from Battle and Buttecreeks. The fish hatchery and Battle and Butte creeks served asreference sites because they had no history of receiving minedrainage. Salmon consumed mostly midge larvae and pupae (44.0%,damp-dry biomass), caddisfly larvae (18.9%), Cladocera (5.8%),and mayfly nymphs (5.7%). These results demonstrated thatinsects selected for metal determinations were important as fishforage. Dry-weight concentrations of Cu, Cd, and Zn weregenerally far higher in salmon and insects from the river thanfrom reference sites. Within the river, high metalconcentrations persisted as far downstream as South Meridian (thelowermost sampling site). Maximum concentrations of Cd (30.7 μg g -1 ) and Zn (1230 μg g -1 ),but not Cu (87.4 μg g -1 ), in insects exceeded amounts that other investigators reported as toxic when fed for prolonged periods to juvenile salmonids.

California↗
USGS2002

Stabilized liquid membrane device (SLMD) for the passive, integrative sampling of labile metals in water

A stabilized liquid membrane device (SLMD) is described for potential use as an in situ, passive, integrative sampler for cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in natural waters. The SLMD (patent pending) consists of a 2.5-cm-wide by 15-cm-long strip of low-density polyethylene (LDPE) layflat tubing containing 1 mL of an equal mixture (v/v) of oleic acid (cis-9-octadecenoic acid) and EMO-8Q (7-[4-ethyl-1-methyloctyl]-8-quinolinol). The reagent mixture continuously diffuses to the exterior surface of the LDPE membrane, and provides for sequestration of several divalent metals for up to several weeks. Depending on sampler configuration, concentration factors of several thousand can be realized for these metal ions after just a few days. In addition to in situ deployment, the SLMD may be useful for laboratory determination of labile metal species in grab samples. Methods for minimizing the effects of water flow on the sampling rate are currently under investigation.

Water, Air, & Soil Pollution↗
USGS2001

Catchment-scale variation in the nitrate concentrations of groundwater seeps in the Catskill Mountains, New York, U.S.A.

Forested headwater streams in the Catskill Mountains of New York show significant among-catchment variability in mean annual nitrate (NO3-) concentrations. Large contributions from deep groundwater with high NO3- concentrations have been invoked to explain high NO3- concentrations in stream water during the growing season. To determine whether variable contributions of groundwater could explain among-catchment differences in streamwater, we measured NO3- concentrations in 58 groundwater seeps distributed across six catchments known to have different annual average streamwater concentrations. Seeps were identified based on release from bedrock fractures and bedding planes and had consistently lower temperatures than adjacent streamwaters. Nitrate concentrations in seeps ranged from near detection limits (0.005 mg NO3--N/L) to 0.75 mg NO3--N/L. Within individual catchments, groundwater residence time does not seem to strongly affect NO3- concentrations because in three out of four catchments there were non-significant correlations between seep silica (SiO2) concentrations, a proxy for residence time, and seep NO3- concentrations. Across catchments, there was a significant but weak negative relationship between NO3- and SiO2 concentrations. The large range in NO3- concentrations of seeps across catchments suggests: 1) the principal process generating among-catchment differences in streamwater NO3- concentrations must influence water before it enters the groundwater flow system and 2) this process must act at large spatial scales because among-catchment variability is much greater than intra-catchment variability. Differences in the quantity of groundwater contribution to stream baseflow are not sufficient to account for differences in streamwater NO3- concentrations among catchments in the Catskill Mountains.

Water, Air, & Soil Pollution↗
USGS2001

Changes in the chemistry of precipitation in the United States, 1981-1998

Regulatory measures in the United States, such as Title IV of the Clean Air Act Amendments of 1990, have primarily restricted sulfur dioxide emissions as a way to control acidic deposition. These restrictions, coupled with increasing concentrations of NH4+ in wet deposition in some regions of the U.S. and continued high emissions of nitrogen oxides have generated a significant shift in the chemistry of precipitation as measured at National Atmospheric Deposition Program/National Trends Network sites. Trends in precipitation chemistry at NADP/NTN sites were evaluated for statistical significance for the period 1981-1998 using a Seasonal Mann-Kendall Test, a robust non-parametric test for detection of monotonic trends. SO42- declines were detected at 100 of the 147 sites examined while no sites exhibited increasing SO42- trends. On average, SO42- declined 35% over the period 1981-1998 with downward SO42- trends being most pronounced in the northeastern United States. In contrast, no consistent trends in NO3- concentrations were observed in precipitation in any major region of the United States. Although the majority of sites did not exhibit significant trends in NH4+ concentration, 30 sites exhibited upward trends. For Ca2+ concentration in precipitation, 64 sites exhibited a significant decreasing trend and no sites exhibited an upward trend.

Water, Air, & Soil Pollution↗
USGS2002

Geographic techniques and recent applications of remote sensing to landscape-water quality studies

This article overviews recent advances in studies of landscape-water quality relationships using remote sensing techniques. With the increasing feasibility of using remotely-sensed data, landscape-water quality studies can now be more easily performed on regional, multi-state scales. The traditional method of relating land use and land cover to water quality has been extended to include landscape pattern and other landscape information derived from satellite data. Three items are focused on in this article: 1) the increasing recognition of the importance of larger-scale studies of regional water quality that require a landscape perspective; 2) the increasing importance of remotely sensed data, such as the imagery-derived normalized difference vegetation index (NDVI) and vegetation phenological metrics derived from time-series NDVI data; and 3) landscape pattern. In some studies, using landscape pattern metrics explained some of the variation in water quality not explained by land use/cover. However, in some other studies, the NDVI metrics were even more highly correlated to certain water quality parameters than either landscape pattern metrics or land use/cover proportions. Although studies relating landscape pattern metrics to water quality have had mixed results, this recent body of work applying these landscape measures and satellite-derived metrics to water quality analysis has demonstrated their potential usefulness in monitoring watershed conditions across large regions.

Water, Air, & Soil Pollution↗
USGS2002

Methylmercury in flood-control impoundments and natural waters of northwestern Minnesota, 1997-99

We studied methylmercury (MeHg) and total mercury (HgT) in impounded and natural surface waters in northwestern Minnesota, in settings ranging from agricultural to undeveloped. In a recently constructed (1995) permanent-pool impoundment, MeHg levels typically increased from inflow to outflow during 1997; this trend broke down from late 1998 to early 1999. MeHg levels in the outflow reached seasonal maxima in mid-summer (maximum of 1.0 ng L −1 in July 1997) and late-winter (maximum of 6.6 ng L −1 in February 1999), and are comparable to high levels observed in new hydroelectric reservoirs in Canada. Spring and autumn MeHg levels were typically about 0.1–0.2 ng L −1 . Overall, MeHg levels in both the inflow (a ditch that drains peatlands) and outflow were significantly higher than in three nearby reference natural lakes. Eleven older permanent-pool impoundments and six natural lakes in northwestern Minnesota were sampled five times. The impoundments typically had higher MeHg levels (0.071–8.36 ng L −1 ) than natural lakes. Five of six lakes MeHg levels typical of uncontaminated lakes (0.014–1.04 ng L −1 ) with highest levels in late winter, whereas a hypereutrophic lake had high levels (0.37–3.67 ng L −1 ) with highest levels in mid-summer. Seven temporary-pool impoundments were sampled during summer high-flow events. Temporary-pool impoundments that retained water for about 10–15 days after innundation yielded pronounced increases in MeHg from inflow to outflow, in one case reaching 4.6 ng L −1 , which was about 2 ng L −1 greater than the mean inflow concentration during the runoff event.

Minnesota↗
USGS2002

Contaminants in arctic snow collected over northwest Alaskan sea ice

Snow cores were collected over sea ice from four northwest Alaskan Arctic estuaries that represented the annual snowfall from the 1995-1996 season. Dissolved trace metals, major cations and anions, total mercury, and organochlorine compounds were determined and compared to concentrations in previous arctic studies. Traces (<4 nanograms per liter, ng L-1) of cis- and trans-chlordane, dimethyl 2,3,5,6-tetrachloroterephthalate, dieldrin, endosulfan II, and PCBs were detected in some samples, with endosulfan I consistently present. High chlorpyrifos concentrations (70-80 ng L-1) also were estimated at three sites. The snow was highly enriched in sulfates (69- 394 mg L-1), with high proportions of nonsea salt sulfates at three of five sites (9 of 15 samples), thus indicating possible contamination through long-distance transport and deposition of sulfate-rich atmospheric aerosols. Mercury, cadmium, chromium, molybdenum, and uranium were typically higher in the marine snow (n = 15) in relation to snow from arctic terrestrial studies, whereas cations associated with terrigenous sources, such as aluminum, frequently were lower over the sea ice. One Kasegaluk Lagoon site (Chukchi Sea) had especially high concentrations of total mercury (mean = 214 ng L-1, standard deviation = 5 ng L-1), but no methyl mercury was detected above the method detection limit (0.036 ng L-1) at any of the sites. Elevated concentrations of sulfate, mercury, and certain heavy metals might indicate mechanisms of contaminant loss from the arctic atmosphere over marine water not previously reported over land areas. Scavenging by snow, fog, or riming processes and the high content of deposited halides might facilitate the loss of such contaminants from the atmosphere. Both the mercury and chlorpyrifos concentrations merit further investigation in view of their toxicity to aquatic organisms at low concentrations.

Water, Air, & Soil Pollution↗
USGS2002

Mercury deposition in snow near an industrial emission source in the western U.S. and comparison to ISC3 model predictions

Mercury (total and methyl) was evaluated in snow samples collected near a major mercury emission source on the Idaho National Engineering and Environmental Laboratory (INEEL) insoutheastern Idaho and 160 km downwind in Teton Range in westernWyoming. The sampling was done to assess near-field (<12 km)deposition rates around the source, compare them to those measured in a relatively remote, pristine downwind location, andto use the measurements to develop improved, site-specific modelinput parameters for precipitation scavenging coefficient and thefraction of Hg emissions deposited locally. Measured snow waterconcentrations (ng L -1 ) were converted to deposition (ugm -2 ) using the sample location snow water equivalent. Thedeposition was then compared to that predicted using the ISC3 airdispersion/deposition model which was run with a range ofparticle and vapor scavenging coefficient input values. Acceptedmodel statistical performance measures (fractional bias andnormalized mean square error) were calculated for the differentmodeling runs, and the best model performance was selected. Measured concentrations close to the source (average = 5.3 ngL -1 ) were about twice those measured in the Teton Range(average = 2.7 ng L -1 ) which were within the expected rangeof values for remote background areas. For most of the samplinglocations, the ISC3 model predicted within a factor of two of theobserved deposition. The best modeling performance was obtainedusing a scavenging coefficient value for 0.25 μm diameterparticulate and the assumption that all of the mercury isreactive Hg(II) and subject to local deposition. A 0.1 μm particle assumption provided conservative overprediction of thedata, while a vapor assumption resulted in highly variable predictions. Partitioning a fraction of the Hg emissions to elemental Hg(0) (a U.S. EPA default assumption for combustion facility risk assessments) would have underpredicted the observed fallout.

Idaho↗
USGS1997

Microbial reduction of iodate

The different oxidation species of iodine have markedly different sorption properties. Hence, changes in iodine redox states can greatly affect the mobility of iodine in the environment. Although a major microbial role has been suggested in the past to account for these redox changes, little has been done to elucidate the responsible microorganisms or the mechanisms involved. In the work presented here, direct microbial reduction of iodate was demonstrated with anaerobic cell suspensions of the sulfate reducing bacterium Desulfovibrio desulfuricans which reduced 96% of an initial 100 ??M iodate to iodide at pH 7 in 30 mM NaHCO3 buffer, whereas anaerobic cell suspensions of the dissimilatory Fe(III)-reducing bacterium Shewanella putrefaciens were unable to reduce iodate in 30 mM NaHCO3 buffer (pH 7). Both D. desulfuricans and S. putrefaciens were able to reduce iodate at pH 7 in 10 mM HEPES buffer. Both soluble ferrous iron and sulfide, as well as iron monosulfide (FeS) were shown to abiologically reduce iodate to iodide. These results indicate that ferric iron and/or sulfate reducing bacteria are capable of mediating both direct, enzymatic, as well as abiotic reduction of iodate in natural anaerobic environments. These microbially mediated reactions may be important factors in the fate and transport of 129I in natural systems.

Water, Air, & Soil Pollution↗
USGS2004

The effect of fire on mercury cycling in the soils of forested watersheds: Acadia National Park, Maine, U.S.A

This study compares mercury (Hg) and methylmercury (MeHg) distribution in the soils of two forested stream watersheds at Acadia National Park, Maine, U.S.A. Cadillac Brook watershed, which burned in 1947, has thin soils and predominantly deciduous vegetation. It was compared to the unburned Hadlock Brook watershed, with thicker soil and predominantly coniferous vegetation. Soils in both watersheds were primarily well drained. The fire had a significant impact on the Cadillac watershed, by raising the soil pH, altering the vegetation, and reducing carbon and Hg pools. Total Hg content was significantly higher (P < 0.05) in Hadlock soils (0.18 kg Hg ha-1) compared to Cadillac soils (0. 13 kg Hg ha-1). Hadlock O horizon had an average Hg concentration of 134??48 ng Hg g-1 dry weight, compared to 103??23 ng Hg g-1 dry weight in Cadillac O horizon. Soil pH was significantly higher in all soil horizons at Cadillac compared to Hadlock soils. This difference was especially significant in the O horizon, where Cadillac soils had an average pH of 3.41??0.22 compared to Hadlock soils with an average pH of 2.99??0.13. To study the mobilization potential of Hg in the O horizons of the two watersheds, batch adsorption experiments were conducted, and the results were modeled using surface complexation modeling. The results of Hg adsorption experiments indicated that the dissolved Hg concentration was controlled by the dissolved organic carbon (DOC) concentration. The adsorption isotherms suggest that Hg is more mobile in the O horizon of the unburned Hadlock watershed because of higher solubility of organic carbon resulting in higher DOC concentrations in that watershed. Methylmercury concentrations, however, were consistently higher in the burned Cadillac O horizon (0.20??0.13 ng Hg g-1 dry weight) than in the unburned Hadlock O horizon (0.07??0.07 ng Hg g-1 dry weight). Similarly, Cadillac soils possessed a higher MeHg content (0.30 g MeHg ha-1) than Hadlock soils (0.16 g MeHg ha-1). The higher MeHg concentrations in Cadillac soils may reflect generally faster rates of microbial metabolism due to more rapid nutrient cycling and higher soil pH in the deciduous forest. In this research, we have shown that the amount of MeHg is not a function of the total pool of Hg in the watershed. Indeed, MeHg was inversely proportional to total Hg, suggesting that landscape factors such as soil pH, vegetation type, or land use history (e.g., fire) may be the determining factors for susceptibility to high Hg in biota. ?? 2004 Kluwer Academic Publisher. Printed in the Netherlands.

Water, Air, & Soil Pollution↗
USGS2004

Relative effect of temperature and pH on diel cycling of dissolved trace elements in Prickly Pear Creek, Montana

Diel (24 hr) cycles in dissolved metal and As concentrations have been documented in many northern Rocky Mountain streams in the U.S.A. The cause(s) of the cycles are unknown, although temperature- and pH-dependent sorption reactions have been cited as likely causes. A light/dark experiment was conducted to isolate temperature and pH as variables affecting diel metal cycles in Prickly Pear Creek, Montana. Light and dark chambers containing sediment and a strand of macrophyte were placed in the stream to simulate instream temperature oscillations. Photosynthesis-induced pH changes were allowed to proceed in the light chambers while photosynthesis was prevented in the dark chambers. Water samples were collected periodically for 22 hr in late July 2001 from all chambers and the stream. In the stream, dissolved Zn concentrations increased by 300% from late afternoon to early morning, while dissolved As concentrations exhibited the opposite pattern, increasing 33% between early morning and late afternoon. Zn and As concentrations in the light chambers showed similar, though less pronounced, diel variations. Conversely, Zn and As concentrations in the dark chambers had no obvious diel variation, indicating that light, or light-induced reactions, caused the variation. Temperature oscillations were nearly identical between light and dark chambers, strongly suggesting that temperature was not controlling the diel variations. As expected, pH was negatively correlated ( P < 0.01) with dissolved Zn concentrations and positively correlated with dissolved As concentrations in both the light and dark chambers. From these experiments, photosynthesis-induced pH changes were determined to be the major cause of the diel dissolved Zn and As cycles in Prickly Pear Creek. Further research is necessary in other streams to verify that this finding is consistent among streams having large differences in trace-element concentrations and mineralogy of channel substrate.

Montana↗
USGS2004

Investigation of differences between field and laboratory pH measurements of national atmospheric deposition program/national trends network precipitation samples

A study was undertaken to investigate differences between laboratory and field pH measurements for precipitation samples collected from 135 weekly precipitation-monitoring sites in the National Trends Network from 12/30/1986 to 12/28/1999. Differences in pH between field and laboratory measurements occurred for 96% of samples collected during this time period. Differences between the two measurements were evaluated for precipitation samples collected before and after January 1994, when modifications to sample-handling protocol and elimination of the contaminating bucket o-ring used in sample shipment occurred. Median hydrogen-ion and pH differences between field and laboratory measurements declined from 3.9 ??eq L-1 or 0.10 pH units before the 1994 protocol change to 1.4 ??eq L-1 or 0.04 pH units after the 1994 protocol change. Hydrogen-ion differences between field and laboratory measurements had a high correlation with the sample pH determined in the field. The largest pH differences between the two measurements occurred for high-pH samples (>5.6), typical of precipitation collected in Western United States; however low- pH samples (<5.0) displayed the highest variability in hydrogen-ion differences between field and laboratory analyses. Properly screened field pH measurements are a useful alternative to laboratory pH values for trend analysis, particularly before 1994 when laboratory pH values were influenced by sample-collection equipment.

Water, Air, & Soil Pollution↗
USGS2004

Mercury content of Illinois soils

For a survey of Illinois soils, 101 cores had been collected and analyzed to determine the current and background elemental compositions of Illinois soils. Mercury and other elements were determined in six samples per core, including a surface sample from each core. The mean mercury content in the surface samples was 33 ?? 20 ??g/kg soil, and the background content was 20 ?? 9 ??g/kg. The most probable sources of mercury in these soils were the parent material, and wet and dry deposition of Hg0 and Hg2+ derived from coal-burning power plants, other industrial plants, and medical and municipal waste incinerators. Mercury-bearing sewage sludge or other fertilizers applied to agricultural fields could have been the local sources of mercury. Although the mercury content correlated with organic carbon content or clay content in individual cores, when all the data were considered, there was no strong correlation between mercury and either the organic carbon or the clay-size content.

Water, Air, & Soil Pollution↗
USGS2004

Selenium in water, sediment, plants, invertebrates, and fish in the Blackfoot River drainage

Nine stream sites in the Blackfoot River watershed in southeastern Idaho were sampled in September 2000 for water, surficial sediment, aquatic plants, aquatic invertebrates, and fish. Selenium was measured in these aquatic ecosystem components, and a hazard assessment was performed on the data. Water quality characteristics such as pH, hardness, and specific conductance were relatively uniform among the nine sites examined. Selenium was elevated in water, sediment, aquatic plants, aquatic invertebrates, and fish from several sites suggesting deposition in sediments and food web cycling through plants and invertebrates. Selenium was elevated to concentrations of concern in water at eight sites (>5 ??g/L), sediment at three sites (>2 ??g/g), aquatic plants at four sites (>4 ??g/g), aquatic invertebrates at five sites (>3 ??g/g), and fish at seven sites (>4 ??g/g in whole body). The hazard assessment of selenium in the aquatic environment suggested low hazard at Sheep Creek, moderate hazard at Trail Creek, upper Slug Creek, lower Slug Creek, and lower Blackfoot River, and high hazard at Angus Creek, upper East Mill Creek, lower East Mill Creek, and Dry Valley Creek. The results of this study are consistent with results of a previous investigation and indicate that selenium concentrations from the phosphate mining area of southeastern Idaho were sufficiently elevated in several ecosystem components to cause adverse effects to aquatic resources in the Blackfoot River watershed. ?? 2004 Kluwer Academic Publishers.

Water, Air, & Soil Pollution↗
USGS2008

Environmental contaminant hazards to wildlife at National Capital region and Mid-Atlantic National Park Service units

Pollutant data for air, water, soil and biota were compiled from databases and internet sources and by staff interviews at 23 National Park Service (NPS) units in 2005. A metric was derived describing the quality and quantity of data for each park, and in combination with known contaminant threats, the need for ecotoxicological study was identified and ranked. Over half of NP units were near Toxic Release Inventory sites discharging persistent pollutants, and fish consumption advisories were in effect at or near 22 of the units. Pesticide and herbicide use was found to be minimal, with the exception of those units with agricultural leases. Only 70 reports were found that describe terrestrial vertebrate environmental contaminant data at or near the units. Of the >75,000 compounds in commerce, empirical exposure data were limited to merely 58 halogenated compounds, insecticides, rodenticides, metals, and some contemporary compounds. Further ecotoxicological monitoring and research is warranted at several units including Shenandoah National Park, Richmond National Battlefield Park, Chesapeake & Ohio Canal National Historical Park, Valley Forge National Historical Park, Hopewell Furnace National Historic Site, Monocacy National Battlefield, and Harpers Ferry National Historical Park. The types of investigations vary according to the wildlife species present and potential contaminant threats, but should focus on contemporary use pesticides and herbicides, polychlorinated biphenyls, mercury, lead, and perhaps antibiotics, flame retardants, pharmaceuticals, and surfactants. Other management recommendations include inclusion of screening level contaminant risk assessments into the NPS Vital Signs Program, development of protocols for toxicological analysis of seemingly affected wildlife, alternative methods and compounds for pest management, and use of non-toxic fishing tackle by visitors.

Book chapter↗
USGS2006

Arsenic, cadmium, lead, and mercury in surface soils, Pueblo, Colorado: Implications for population health risk

Decades of intensive industrial and agricultural practices as well as rapid urbanization have left communities like Pueblo, Colorado facing potential health threats from pollution of its soils, air, water and food supply. To address such concerns about environmental contamination, we conducted an urban geochemical study of the city of Pueblo to offer insights into the potential chemical hazards in soil and inform priorities for future health studies and population interventions aimed at reducing exposures to inorganic substances. The current study characterizes the environmental landscape of Pueblo in terms of heavy metals, and relates this to population distributions. Soil was sampled within the city along transects and analyzed for arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb). We also profiled Pueblo's communities in terms of their socioeconomic status and demographics. ArcGIS 9.0 was used to perform exploratory spatial data analysis and generate community profiles and prediction maps. The topsoil in Pueblo contains more As, Cd, Hg and Pb than national soil averages, although average Hg content in Pueblo was within reported baseline ranges. The highest levels of As concentrations ranged between 56.6 and 66.5 ppm. Lead concentrations exceeded 300 ppm in several of Pueblo's residential communities. Elevated levels of lead are concentrated in low-income Hispanic and African-American communities. Areas of excessively high Cd concentration exist around Pueblo, including low income and minority communities, raising additional health and environmental justice concerns. Although the distribution patterns vary by element and may reflect both industrial and non-industrial sources, the study confirms that there is environmental contamination around Pueblo and underscores the need for a comprehensive public health approach to address environmental threats in urban communities. ?? Springer 2006.

Environmental Geochemistry and Health↗
USGS2004

The missing flux in a 35S budget for the soils of a small polluted catchment

A combination of cosmogenic and artificial 35S was used to assess the movement of sulfur in a steep Central European catchment affected by spruce die-back. The Jezer??i?? catchment, Krus??ne?? Hory Mts. (Czech Republic) is characterized by a large disproportion between atmospheric S input and S output via stream discharge, with S output currently exceeding S input three times. A relatively high natural concentration of cosmogenic 35S (42 mBq L-1) was found in atmospheric deposition into the catchment in winter and spring of 2000. In contrast, stream discharge contained only 2 mBq L-1. Consequently, more than 95% of the deposited S is cycled or retained within the catchment for more than several months, while older S is exported via surface water. In spring, when the soil temperature is above 0 ??C, practically no S from instantaneous rainfall is exported, despite the steepness of the slopes and the relatively short mean residence time of water in the catchment (6.5 months). Sulfur cycling in the soil includes not just adsorption of inorganic sulfate and biological uptake, but also volatilization of S compounds back into the atmosphere. Laboratory incubations of an Orthic Podzol from Jezer??i?? spiked with h 720 kBq of artificial 35S showed a 20% loss of the spike within 18 weeks under summer conditions. Under winter conditions, the 35S loss was insignificant (< 5%). This missing S flux was interpreted as volatilized hydrogen sulfide resulting from intermittent dissimilatory bacterial sulfate reduction. The missing S flux is comparable to the estimated uncertainty in many catchment S mass balances (??10%), or even larger, and should be considered in constructing these mass balances. In severely polluted forest catchments, such as Jezer??i??, sulfur loss to volatilization may exceed 13 kg ha-1 a-1, which is more than the current total atmospheric S input in large parts of North America and Europe. ?? 2004 Kluwer Academic Publishers.

Water, Air, and Soil Pollution: Focus↗