The contents of ten elements [Cd, Pb, W, Zn, Mn, As, Se, Cr, Cu, and organic carbon (Corg)] have been determined in the surficial sediments of Keratsini harbor, Saronikos Gulf, Greece. The contamination of the sediments was assessed on the basis of geoaccumulation index and to corresponding sediment quality guidelines (SQGs) effects range low/effects range median. The results revealed highly elevated Cd, Pb, W, Zn, As, Se, Cr, Cu, and Corg values (Cd, 190-1,763 mg kg⁻¹; Pb, 521-1,263 mg kg⁻¹; W, 38-100 mg kg⁻¹; Zn, 409-6,725 mg kg⁻¹; Mn, 95-1,101 mg kg⁻¹; As, not detectable-1,813 mg kg⁻¹; Se, not detectable-58 mg kg⁻¹; Cr, 264-860 mg kg⁻¹; Cu, 195-518 mg kg⁻¹; and Corg, 0.69-4.41%). The enrichment of metals in the sediments results from the contribution of the central Athens sewage outfall through which the waste of the Attica basin ends up in Keratsini harbor as well as from industrial and ship contaminants.

Air pollution associated with particulate matters is a serious problem in the mineral products industrial area (MPIA) in Saraburi, central Thailand. PM₁₀ concentrations monitored at Nah Phra Laan station located in the MPIA show that PM₁₀ levels exhibit strong seasonal variations; the number of days in 2005 that PM₁₀ concentrations exceeded the daily National Ambient Air Quality Standard of 120 μg/m³ were 58%, 29%, and 12% in the winter, rainy, and summer seasons, respectively. In this paper, the Hybrid Particle And Concentration Transport (HYPACT) model with meteorological fields from the Regional Atmospheric Modeling System (RAMS) was applied to Saraburi to investigate the impacts of meteorological parameters upon seasonal variations in PM₁₀ concentration. Analysis of model results shows that daily average PM₁₀ concentrations exceeding 200 μg/m³ are found in the downwind direction of emission sources and their horizontal gradients are strong. Hourly PM₁₀ concentrations exhibit obvious diurnal variation with maximum values in wintertime at around 2000-2100 local standard time in association with low ventilation with light wind speed and weak vertical mixing, while in the rainy season, they are generally higher in the daytime than in the nighttime, as that mixing height in cloudy days is low in daytime whereas emission rates are high during working time.

The purpose of this study was to gather information on the spatial and temporal variation of stream water total mercury concentrations ([THg]) and to test the hypothesis that stream water [THg] increases as stream pH decreases in the Shenandoah National Park (SNP). We based our hypothesis on studies in lakes that found mercury methylation increases with decreasing pH, and studies in streams that found total mercury and other trace metal concentrations increase with decreasing pH. Stream water was collected at baseflow in SNP in April, July, and October 2005 and February 2006. Contrary to our hypothesis, stream water [THg] decreased with decreasing pH and acid neutralizing capacity. In SNP, stream pH and acid neutralizing capacity are strongly influenced by bedrock geology. We found that bedrock also influences stream water [THg]. Streams on basaltic bedrock had higher [THg] (0.648 ng L⁻¹ ± 0.39) than streams on siliciclastic bedrock (0.301 ng L⁻¹ ± 0.10) and streams on granitic bedrock (0.522 ng L⁻¹ ± 0.06). The higher pH streams on basaltic bedrock had the highest [THg]. The variation in stream water [THg] occurred despite no known variation in wet deposition of mercury across the SNP. The findings of this study indicate that the SNP can be an important area for mercury research with significant variations in mercury concentrations across the park.

Desorption of Cu, Cr, Pb, and Zn from industrially polluted soils as a result of acidification is in focus. The eight soils of the investigation vary greatly in composition and heavy metal concentration/combination. Three soils had elevated concentrations of Cu, Pb, and Zn; regardless of pollution level, pollution origin, and soil type, the order for desorption as pH decreased was Zn > Cu > Pb. Turning to a single heavy metal in different soils, there was a huge difference in the pH at which the major desorption started. The variation was most significant for Pb where, e.g., less than 10% was desorbed at pH 2.5 from one soil, whereas in another soil 60% Pb was desorbed at this pH. Sequential extraction was made and the soils in which a high percentage of Pb was found in the residual phase (adsorbed strongest) was also the soils where less Pb was desorbed at low pH in the desorption experiments. It was evident that Cu, Pb, and Zn started to desorb at a higher pH from calcareous soils than from soils with low carbonate content. The mechanism responsible for this is co-precipitation of heavy metals in the carbonates. When the carbonates are dissolved at a relatively high pH of about 5, the co-precipitated heavy metals are released. The sequential extraction pattern for Cr differed generally much from the other heavy metals since the majority of Cr was extracted in the last two steps. Cr was also the heavy metal that desorbed the least at high acidification.

Regressions of aluminum against potentially toxic elements in the sediments of freshwater aquatic systems in Louisiana were used to distinguish natural variability from anthropogenic pollution when elemental concentrations exceeded screening effects levels. The data were analyzed using geometric mean model II regression methods to minimize, insofar as possible, bias that would have resulted from the use of model I regression. Most cadmium concentrations exceeded the threshold effects level, but there was no evidence of an anthropogenic impact. In Bayou Trepagnier, high concentrations of Cr, Cu, Pb, Ni, and Zn appeared to reflect anthropogenic pollution from a petrochemical facility. In Capitol Lake, high Pb concentrations were clearly associated with anthropogenic impacts, presumably from street runoff. Concentrations of potentially toxic elements varied naturally by as much as two orders of magnitude; hence it was important to filter out natural variability in order to identify anthropogenic effects. The aluminum content of the sediment accounted for more than 50% of natural variability in most cases. Because model I regression systematically underestimates the magnitude of the slope of the regression line when the independent variable is not under the control of the investigator, use of model II regression methods in this application is necessary to facilitate hypothesis testing and to avoid incorrectly associating naturally high elemental concentrations with human impacts.

This study was conducted to determine the metal (Ag, Al, As, Cd, Co, Cu, Fe, Mn, Ni, Pb, Sb, Zn) tolerance and uptake of Mitchell grasses when grown on waste rocks and tailings of a base metal mine, Australia. The objective of conducting such phytoremediation studies was to gain data relating to the implementation and effectiveness of capping and revegetation strategies for mine waste repositories in regions of native grasslands. Pot trials demonstrate that Mitchell grasses are metal tolerant and have the ability to accumulate significant concentrations of metals (Pb, Zn) into their above-ground biomass. Concentrations of metals in Mitchell grasses were evaluated in terms of maximum allowable dietary levels in livestock. The pot trial project revealed that if Mitchell grasses were to be used for mined land reclamation and were grown on tailings, the grasses could potentially accumulate large quantities of Zn in their tissue, potentially causing harmful effects on animals feeding on them. Hence, it is undesirable that Mitchell grasses are grown on and their root system come in contact with tailings with elevated level of Zn. Otherwise, the species may accumulate phyto- and zootoxic concentrations of Zn. The metal tolerance, the tendency to accumulate metals in the above-ground biomass and the significant root penetration depth of Mitchell grasses have implications for the design of tailings storage facilities. Capping of waste repositories, containing elevated metal concentrations and using a cover system without capillary breaks, clay layers or alternative strategies, may not be sustainable in the long term. The application of phosphate amendments to tailings may represent an alternative strategy to limit the uptake of metals by Mitchell grasses. The pot trials prove that the addition of phosphate to mine wastes decreases the bio-availability of metals in these materials and reduces the Pb and Zn concentration in Mitchell grasses growing on them. Thus, the addition of phosphate amendments to the top layers of metalliferous mine wastes may represent an alternative waste management strategy.

Flooded post-harvest rice paddies were examined as systems for reducing diazinon (organophosphate insecticide) concentrations in stormwater runoff. Two paddies were cultivated in Oryza sativa L. and amended with a 3-h simulated stormwater diazinon runoff event. Initial diazinon adsorption peaked at 347 and 571 μg kg⁻¹ (3% mass load reduction) for mean above-ground plant tissue concentrations in each pond, respectively. Subsequent senescence of above-ground tissue showed significant decreases in tissue mass (r ² = 0.985) and adsorbed diazinon mass (90 ± 4% and 82 ± 1%) within 1 month of amendment. There were no corollary increases in water column diazinon concentrations. Furthermore, control O. sativa tissue placed within the treatment ponds had below-detectable levels of diazinon throughout the decomposition phase, suggesting a lack of within pond transference of dissipated diazinon. This study shows the relative effectiveness of diazinon adsorption by post-harvest rice plants and a potential mitigation strategy of senescence and pesticide degradation for contaminated tailwater.

The Sulphur Bank Mercury Mine (SBMM), active intermittently from 1873-1957 and now a USEPA Superfund site, was previously estimated to have contributed at least 100 metric tons (10⁵ kg) of mercury (Hg) into the Clear Lake aquatic ecosystem. We have confirmed this minimum estimate. To better quantify the contribution of the mine in relation to other sources of Hg loading into Clear Lake and provide data that might help reduce that loading, we analyzed Inputs and Outputs of Hg to Clear Lake and Storage of Hg in lakebed sediments using a mass balance approach. We evaluated Inputs from (1) wet and dry atmospheric deposition from both global/regional and local sources, (2) watershed tributaries, (3) groundwater inflows, (4) lakebed springs and (5) the mine. Outputs were quantified from (1) efflux (volatilization) of Hg from the lake surface to the atmosphere, (2) municipal and agricultural water diversions, (3) losses from out-flowing drainage of Cache Creek that feeds into the California Central Valley and (4) biotic Hg removal by humans and wildlife. Storage estimates include (1) sediment burial from historic and prehistoric periods (over the past 150-3,000 years) from sediment cores to ca. 2.5m depth dated using dichloro diphenyl dichloroethane (DDD), ²¹⁰Pb and ¹⁴C and (2) recent Hg deposition in surficial sediments. Surficial sediments collected in October 2003 (11 years after mine site remediation) indicate no reduction (but a possible increase) in sediment Hg concentrations over that time and suggest that remediation has not significantly reduced overall Hg loading to the lake. Currently, the mine is believed to contribute ca. 322-331 kg of Hg annually to Clear Lake, which represents ca. 86-99% of the total Hg loading to the lake. We estimate that natural sedimentation would cover the existing contaminated sediments within ca. 150-300 years.

This study assessed the arsenic and heavy metal contaminations of agricultural soils around the tin and tungsten mining areas in Dai Tu district in northern Vietnam. Among the examined elements, high total contents of As and Cu were found in the agricultural fields at both tin and tungsten mining sites. Although the major part of the accumulated As and Cu were bound by various soil constituents such as Fe and Mn oxides, organic matter, and clay minerals, increases in water soluble As and Cu were observed, especially for the paddy fields. The results suggest that, in the studied area, As and Cu dispersion from their pollution sources into farmlands is mainly via fluvial transportation of mine waste through streams that cross the paddy fields around the tin mining area, and soil erosion at the tea fields located at lower positions of the slope in the tungsten mining area.

Immobilization of metals by two materials (zeolite, AZ, and a synthetic, carbonate-rich material, “slovakite”, SL) was tested in a pot experiment with two soils from urban areas of Sevilla and two soils affected by a mine spill. Barley (Hordeum vulgare L. Hispanic) was grown in the pots, and metal contents were measured after 31 days in shoots and roots. Available metal was estimated by extraction with CaCl₂ (readily soluble), ethylenediaminetetraacetic acid (EDTA; plant available), a mixture of organic acids (soluble by root exudates), and glycine (bioaccessible by ingestion). Neither treatment caused significant differences on plant growth or metal contents of shoots, whereas roots contained more Cu in the SL treatments. Root Zn uptake was reduced in all cases, but reduction of Pb in roots was observed only in AZ treatments of the mine-spill soils. The effects on metal availability were often method-dependent. Decrease of CaCl₂ data were observed only in the mine-spill soils. EDTA-soluble metals were clearly decreased by both materials. Bioaccessible Zn were decreased by either material in several cases (but not in the most heavily polluted soil), whereas Cu or Pb data were less conclusive.