Mercury emission and dispersion models from soils contaminated by cinnabar mining and metallurgy

The laboratory flux measurement system (LFMS) and dispersion models were used to investigate the kinetics of mercury emission flux (MEF) from contaminated soils. Representative soil samples with respect to total Hg concentration (26-9770 μg g(-1)) surrounding a decommissioned mercury-mining area (Las Cuevas Mine), and a former mercury smelter (Cerco Metalúrgico de Almadenejos), in the Almadén mercury mining district (South Central Spain), were collected. Altogether, 14 samples were analyzed to determine the variation in mercury emission flux (MEF) versus distance from the sources, regulating two major environmental parameters comprising soil temperature and solar radiation. In addition, the fraction of the water-soluble mercury in these samples was determined in order to assess how MEF from soil is related to the mercury in the aqueous soil phase. Measured MEFs ranged from less than 140 to over 10,000 ng m(-2) h(-1), with the highest emissions from contaminated soils adjacent to point sources. A significant decrease of MEF was then observed with increasing distance from these sites. Strong positive effects of both temperature and solar radiation on MEF was observed. Moreover, MEF was found to occur more easily in soils with higher proportions of soluble mercury compared to soils where cinnabar prevails. Based on the calculated Hg emission rates and with the support of geographical information system (GIS) tools and ISC AERMOD software, dispersion models for atmospheric mercury were implemented. In this way, the gaseous mercury plume generated by the soil-originated emissions at different seasons was modeled. Modeling efforts revealed that much higher emissions and larger mercury plumes are generated in dry and warm periods (summer), while the plume is smaller and associated with lower concentrations of atmospheric mercury during colder periods with higher wind activity (fall). Based on the calculated emissions and the model implementation, yearly emissions from the "Cerco Metalúrgico de Almadenejos" decommissioned metallurgical precinct were estimated at 16.4 kg Hg y(-1), with significant differences between seasons.     

Mercury fractionation in contaminated soils from the Idrija mercury mine region

Mercury (Hg) fractionation was investigated in contaminated soil in the Idrija Hg-mine region, Slovenia. The main aim of this study was to test and apply sequential extraction and quantification of different Hg phases in order to estimate the mobility and potential bioavailability of Hg in contaminated soils. Separation of Hg phases was performed by means of a selective sequential extraction procedure complemented by volatilization of elemental mercury (Hg0). The influence of temperature, moisture and storage on Hg0 volatilization was also investigated. The total Hg concentrations varied between 8.4 and 415 mg kg(-1) and were up to 40-fold higher than the maximum permissible set by Slovenian legislation. Fractionation measurements indicated cinnabar as the predominant Hg fraction, followed by Hg0. Accumulation of cinnabar predominantly occurred in coarse grained flood plain sediments, where on average it constituted more than 80% of total Hg. In contrast non-cinnabar fractions were found to be enriched in areas where fine grained material was deposited, reaching up to 60% of total Hg. The strong positive correlation (R2 = 0.71-0.99) among non-cinnabar fractions suggested that these fractions predominantly control the mobility and potential bioavailability of Hg. Sample pretreatment before fractionation influenced the partition of Hg between different fractions, and therefore fractionation in fresh, nontreated samples is suggested. In addition, the specificity of the extraction steps needs further attention, as it was shown that some extraction steps, such as the organo-chelating Hg fraction, do not provide meaningful results. This further suggests that protocols for mercury fractionation need further harmonization in order to improve the comparability of the results and their use in risk assessment. Volatile mercury fluxes averaged between 0.04 and 6.5 ng g(-1) h(-1). Good agreement (R2 = 0.81-0.95) was found between the non-cinnabar fractions and evaporation of Hg0. Both the temperature and sample moisture had significant effects on mercury volatilization. The results in this study were obtained at 70 degrees C, which may be somewhat high, in particular for bacterial activity which may also play an important role in Hg volatilization. Therefore it is strongly suggested that further optimisation of the protocol to assess Hg volatilization from soil is required.     

Mercury speciation in the Persian Gulf sediments

The concentrations of total mercury (Hg) and methyl mercury (MMHg) were determined in 78 marine sediments in the Iranian coastal waters of the Persian Gulf along nine transects perpendicular to the coastline. Total Hg ranged from 10 to 56 ng g( - 1)d.w. and MMHg from 0.1 to 0.4 ng g( - 1) d.w. The fraction of methyl mercury accounted from 0.3% to 1.1% of the total mercury amount. The organic carbon (OC) content ranged from 0.4% to 1.8%. The present study indicates that the levels of Hg in the sediments of the Iranian coast of the Persian Gulf were all in the concentration range of unpolluted areas regarding Hg (<100 ng g( - 1)). The concentrations of total Hg, methyl mercury and organic carbon were generally higher in the deeper stations. Total Hg and MMHg were significantly correlated, but no significant correlations could be found between the Hg and OC levels.     

Assessment of carcinogenic heavy metal levels in Brazilian cigarettes

Total mercury (Hg(T)) and bioavailability Hg (Hg(HCl)) concentrations in soil were determined in five districts in Wuhu urban area. Spatial pattern of soil Hg concentration was generated through kriging technology. Results showed that Hg concentration in soil ranged from 0.024 to 2.844 mg kg(?-1) with an average of 0.207 mg kg(?-1). Hg concentration in soil appeared to have a block distribution and decreased from downtown to surrounding district. And Hg concentrations appeared to have a medium scale spatial auto correlation, strongly affected by human activity. The maximal Hg average concentration (0.332 mg kg(?-1)) in soil appeared in Jinghu district, where the high intensity of human activities is. Second highest Hg average concentration (0.263 mg kg(?-1)) in soil appeared in development district, where the intensive industrial activities are. Bioavailability Hg concentration in soil ranged from 2.6 to 4.9 μg kg(?-1) with an average of 3.8 μg kg(?-1), which had a ratio of 0.28~6.44% to total Hg. The ratios of bioavailability Hg to total Hg in vegetable soil were bigger than those of park soil. Correlation analysis showed that total Hg, organic matter, total phosphorus, and bioavailability Hg concentrations in soil were significantly positively correlated. Hg concentration in vegetable ranged from 2.7 to 15.2 μg kg(?-1) with an average of 6.5 μg kg(?-1). Hg concentration in vegetable was positively correlated with Hg(HCl) concentration in soil. According to the calculation on hazard quotient (HQ) for children, inhalation of Hg vapor from soil is the main exposure pathway, in which HQ is 2.517 × 10(?-2), accounting for 80.3% of the four exposure pathways. Hazard index (HI) of the four exposure pathways is lower than the "safe" level of HI = 1; therefore, exposure of soil Hg exhibited little potential health risk to children in Wuhu urban area.     

Mercury concentration in fish from Piracicaba River (Minas Gerais, Brazil)

Mercury emissions from some upstream gold mining areas and recent findings of high natural Hg levels in sediments motivated studies on the Hg cycle in the Minas Gerais state. The study presents the total mercury amount found in Geophagus brasiliensis' muscular tissue (wet weight) and sediments from Piracicaba River. Mercury was analyzed using acid digestion followed by determination of total mercury by cold vapour atomic absorption spectrophotometry. This study was also complemented with the analysis of the limnological parameters (water temperature, conductivity, total dissolved solids, suspended particles, pH, dissolved oxygen, maximum depth, photic index and total carbon). The mercury concentration in sediments samples was higher than the mercury concentration in muscular tissue of fish. The lowest Hg level measured in fish was 0.0147 microg g( - 1), while the highest was 0.101 microg g( - 1). In the sediment samples, the lowest and highest levels were 0.02 microg g( - 1) and 0.16 microg g( - 1), respectively. The Hg concentrations in fish and sediment were both under the maximum limit permitted by the World Health Organization.     

Gold Concentrations in Abiotic Materials, Plants, and Animals: A Synoptic Review

Gold (Au) is ubiquitous in the environment and mined commercially at numerous locations worldwide. It is also an allergen that induces dermatitis in sensitive individuals. Gold concentrations were comparatively elevated in samples collected near gold mining and processing facilities, although no data were found for birds and non-human mammals. Maximum gold concentrations reported in abiotic materials were 0.001 microg L(-1) in rainwater; 0.0015 microg L(-1) in seawater near hydrothermal vents vs. < 0.00004-0.0007 microg L(-1) elsewhere; 5.0 microg kg(-1) dry weight (DW) in the Earth's crust; 19.0 microg L(-1) in a freshwater stream near a gold mining site; 440 microg kg(-1) DW in atmospheric dust near a high traffic road; 843 microg kg(-1) DW in alluvial soil near a Nevada gold mine vs. < 29 microg kg(-1) DW premining; 2.53 mg kg(-1) DW in snow near a Russian smelter vs. < 0.35 mg kg(-1) DW at a reference site; 4.5 mg kg(-1) DW in sewage sludge; 28.7 mg kg(-1) DW in polymetallic sulfides from the ocean floor; and 256.0 mg kg(-1) DW in freshwater sediments near a gold mine tailings pile vs. < 5 microg kg(-1) DW prior to mining. In plants, elevated concentrations of 19 microg Au kg(-1) DW were reported in terrestrial vegetation near gold mining operations vs. < 4 microg kg(-1) DW at a reference site; 37 microg kg(-1) DW in aquatic bryophytes downstream from a gold mine; 150 microg Au kg(-1) DW in leaves of beans grown in soil containing 170 microg kg(-1) DW; up to 1.06 mg kg(-1) DW in algal mats of rivers receiving gold mine wastes; and 0.1-100 mg kg(-1) DW in selected gold accumulator plants. Fish and aquatic invertebrates contained 0.1-38.0 microg Au kg(-1) DW. In humans, gold concentrations up to 1.1 microg L(-1) were documented in urine of dental technicians vs. 0.002-0.85 microg L(-1) in reference populations; 2.1 microg L(-1) in breast milk, attributed to gold dental fillings and jewelry of mothers; 1.4 mg kg(-1) DW in hair of goldsmiths vs. a normal range of 6-880 microg kg(-1) DW; 2.39 mg L(-1) in whole blood of rheumatoid arthritis patients receiving gold thiol drugs to reduce inflammation (chrysotherapy) vs. a normal range of 0.2-2.0 microg L(-1); and 60.0 to 233.0 mg kg(-1) fresh weight (FW) in kidneys of rheumatoid arthritis patients undergoing active chrysotherapy vs. < 42.0 mg kg(-1) FW kidney 140 months posttreatment.     

Sand as a relevant fraction in geochemical studies in intertidal environments

Soil and sediment samples from several intertidal environment exposed to different types of contamination were studied to investigate the importance of grain size in relation to the capacity of the substrates to retain trace metals. The unfractionated samples (referred to as bulk samples) were separated into the following grain/size fractions: fine–coarse sand (2?0.100 mm), very fine sand (0.100?0.050 mm), silt (0.050?0.002 mm), and clay (0.002 mm). The sample into its fractions was carried out was in a glove box under high-purity N₂ atmosphere in order to minimize any alterations to the samples. The bulk samples were characterized in terms of physicochemical properties such as pH, redox potential, and grain size. The total organic carbon (TOC), total sulfur (S), iron (Fe) pyrite, Fe, and manganese (Mn), and trace metals lead (Pb), mercury (Hg), chromium (Cr), and nickel (Ni) were analyzed in the bulk samples and in each fraction. The sand fractions were also examined by scanning electron microscopy (SEM). Comparisons of the above parameters were made between fractions and between each fraction and the corresponding bulk sample. The fine–coarse sand fraction contained high levels of the primary elements of the geochemical processes that occur in marine sedimentary environments such as TOC, total Fe, Mn, and S. The net concentrations of these four elements were higher in the fine-coarse sand fraction than in the very fine sand fraction and were similar to the net concentrations in the silt and clay fractions. Detailed SEM analysis of the sand coarse fraction revealed the presence of Fe and aluminum oxyhydroxide coatings in the oxic layers, whereas the framboidal pyrites and coatings observed in the anoxic layers were Fe sulfides. The presence of the various coatings explains why the trace metal concentrations in the sand fine–coarse fraction were similar to those in the clay fraction and higher than those in the very fine sand fraction. The present results highlight the importance of the sand fraction, which is generally disregarded in geochemical and environmental studies of sedimentary layers.     

Trace metal bioaccumulation in eight common coastal Australian polychaeta

Whole tissue trace metal concentrations of ten metals in eight common coastal Australian polychaete species collected from uncontaminated locations were measured. The mean concentration range for each trace metal was: Mn: 2.6-13 microg g(-1); Co: 0.8-4.6 microg g(-1); Cu: 3.4-26 microg g(-1); Zn: 47-225 microg g(-1); As: 18-101 microg g(-1); Se: 2.2-20.4 microg g(-1); Ag: 0.03-2.5 microg g(-1); Cd: 0.07-17 microg g(-1); Hg: 0.08-0.88 microg g(-1) and Pb: 0.09-3.2 microg g(-1)dry mass. Principal components analysis of trace metal signatures revealed that the habitat, i.e. exposed coast sand or rock, estuarine sand or estuarine mud substrate in which a polychaete species was found, had a significant influence on the bioaccumulation of six trace metals (Mn, Cu, Zn, Ag, Cd and Pb). However, there is no clear relationship between trace metal concentrations in substrates and polychaetes. The results of the current study contribute to a reference dataset of polychaete species-specific natural background trace metal concentrations for use in determining the extent of trace metal contamination by urban and industrial sources.     

Polychlorinated biphenyls in marine sediments from the southern North Sea and Scheldt estuary: a ten-year study of concentrations, patterns and trends

The paper reports the concentrations and patterns of CBs in sediments of the Belgian part of the southern North Sea and the Scheldt estuary for the period 1991-2001. The long-term analytical performance was well within the quality assurance boundaries set at the outset of the study and is consistent with the state of the art for this type of analysis. The CB concentrations (given as the median of the sum of IUPAC Nos 28, 52, 101, 118, 138, 153 and 180) vary between 0.1 microg kg(-1) and 50 microg kg(-1) dry weight in the total sediment and it could be demonstrated that CB patterns in the fine fraction of the sediment were closely similar throughout the investigated area. Isolation of the fine fraction (<63 microm) by sieving can be regarded as a physical normalisation to reduce the differences in sediment granulometric composition. It allows for a better understanding of CB distribution and patterns and improves the trend analysis. A significant downward trend could not be found at any of the stations, which suggests that CB levels have not been changing in the area of interest in the past decade.     

Description and evaluation of a sampling system for monitoring hydrocarbons in sediments

A composite random sampling design was used to estimate the concentrations of hydrocarbons in sediments from two near-shore areas of Scotland (Firth of Clyde and Firth of Forth). The aim of this work was to estimate a mean value for each parameter in these areas, and to determine whether this can be done with more thorough coverage (better representation), better precision and less variance at lower analytical cost through a composite random sampling scheme rather than a simple random sampling scheme, and thereby contribute to the re-design of the UK National Marine Monitoring Programme (NMMP), re-named the UK Clean Seas Environmental Monitoring Programme (CSEMP) in 2006. Samples were collected using a simple random sampling design during 2005. All sediment samples were analysed for their particle size distribution and total organic carbon (TOC). All sediments were analysed for polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. The concentrations of PAHs and n-alkanes in the study areas are described, and sources of PAHs were investigated through the PAH distributions and n-alkane profiles. Individual sediment samples from each area were combined to give a series of composite sub-samples, each comprised of 5 individual sediment samples. These composite samples were re-analysed for the same parameters as the individual samples. Mean total PAH (2- to 6-ring parent and branched) concentrations, based on the individual original sediment samples collected through simple random sampling, were 1858 microg kg(-1) dry weight (SE = 196 microg kg(-1) dry weight, n = 25) and 532.4 microg kg(-1) dry weight (SE = 59 microg kg(-1) dry weight, n = 25) in the Clyde and Forth, respectively. Mean total PAH concentrations of the composite samples were 1745 microg kg(-1) dry weight (SE = 121.0 microg kg(-1) dry weight, n = 5) in the Clyde and 511.6 microg kg(-1) dry weight (SE = 37.4 microg kg(-1) dry weight, n = 5) in the Forth. No significant differences were found between the mean PAH concentrations from the two sampling designs. This study demonstrated that the composite random sampling design gave a mean value with less variance than the simple random sampling design, at significantly reduced analytical effort (and cost).     

Development of an extraction method for perchlorate in soils

Perchlorate originates as a contaminant in the environment from its use in solid rocket fuels and munitions. The current US EPA methods for perchlorate determination via ion chromatography using conductivity detection do not include recommendations for the extraction of perchlorate from soil. This study evaluated and identified appropriate conditions for the extraction of perchlorate from clay loam, loamy sand, and sandy soils. Based on the results of this evaluation, soils should be extracted in a dry, ground (mortar and pestle) state with Milli-Q water in a 1 ratio 1 soil ratio water ratio and diluted no more than 5-fold before analysis. When sandy soils were extracted in this manner, the calculated method detection limit was 3.5 microg kg(-1). The findings of this study have aided in the establishment of a standardized extraction method for perchlorate in soil.     

Mercury fractionation in stream sediments from the Quadrilátero Ferrífero gold mining region, Minas Gerais State, Brazil

The Iron Quadrangle (IQ) region, located in the state of Minas Gerais, has been the most important gold producing area in Brazil since the end of seventeenth century. The use of mercury for gold amalgamation in small scale mines has been responsible for large release of Hg to aquatic and terrestrial environments during 300 years of mining. The present work sought to evaluate the fractionation of Hg in stream sediments is the southern region of the IQ by utilizing sequential extraction. Since mobility and availability of Hg are related to its distribution among sediment partitions, fractionation methods provide detailed information on the ecotoxicological impact and risks associated to the presence of Hg in sediments. The total Hg concentration varied from 179.3 to 690.1 microg kg( - 1) and Hg(0) accounted for the majority at all sample sites, ranging from 42% to 56% of the total.     

Total mercury levels in nine species of freshwater fish from two hydroelectric reservoirs and a crater lake in Ghana

Total mercury (Hg) concentrations were determined in the muscle tissue of fish from three reservoirs in Ghana, namely, Lake Bosomtwi, Kpong and Akosombo Hydroelectric Reservoirs. A total of 165 fish samples covering nine species were collected and analysed for total mercury. A mixture of HNO3, H2SO4 and HClO4 were used for complete oxidation of organic tissues. Hg was detected by the Cold Vapour Atomic Absorption Spectrometry technique using an automatic mercury analyzer. Total mercury concentrations in microg g(-1) (wet weight) ranged from below 0.001 to 0.070 for fish from Lake Bosomtwi, 0.010 to 0.275 for fish from Kpong Reservoir and from below 0.001 to 0.042 for fish from Akosombo Reservoir. All the results obtained are below the World Health Organization limit of 0.5 microg g(-1). The low levels of total mercury obtained in this study suggest that the three aquatic environments have not been significantly impacted by mercury contamination.     

Cloud water and throughfall deposition of mercury and trace elements in a high elevation spruce-fir forest at Mt. Mansfield,Vermont

As part of the Lake Champlain Basin watershed study of mercury (Hg) and pollutant deposition, cloud water and cloud throughfall collections were conducted at the south summit (1204 m) of Mt. Mansfield, Vermont between August 1 and October 31, 1998, for multi-element chemical analysis. A passive Teflon string collector was deployed during non-precipitating events to sample cloud/fog water at timberline, while three sets of paired funnels collected cloud throughfall under the red spruce-balsam fir canopy. Samples were analyzed for concentrations of Hg, major ions, and 10 trace elements. Ultra-clean sampling and analysis techniques were utilized throughout the study. Six events were sampled for cloud water alone and four events were sampled for both cloud water and cloud throughfall. Cloud throughfall chemistry showed substantial modification from incident cloud water. Much higher concentrations of Hg (2.3 x), base cations (Ca2+, K-, Mg2+; 3-18 x) and certain trace elements (Ni, Cu, Mn, Rb, Sr; 2-34 x) were observed in throughfall than in cloud water. These results confirm that cloud water can leach a wide variety of elements from tree foliage and wash off dry deposited elements. Cloud water deposited an average of 0.42 +/- 0.12 mm of water per hour. Estimated cloud water deposition of Hg was 7.4 microg m(-2) for the period August 1-October 31, approximately twice that deposited by rain during this period at a nearby low elevation Hg monitoring site. Our results indicate that cloud water and Hg deposition at Mt. Mansfield are likely to have considerable ecological effects.     

Mercury in chemical fractions of recent pelagic sediments of the sea of Japan

The distribution of mercury (Hg) in chemical fractions (H2O, 0.05 M Na2-EDTA pH 3, 1 M HCl, humic and fulvic acids, and non-hydrolysing residue) of recent pelagic sediment cores of the Sea of Japan (East Sea) was studied. Total Hg content in the sediments was rather low: 83 +/- 30 (21-173) etag g(-1), indicating the absence of substantial specific sources of the element in the deep part of the sea. Hg content within the sediment core varied by a factor of 1.3-1.8, showing peaks that coincide with the near-surface and buried sediment slices of light brown and brown "oxidized" colours and evidencing Hg redox-sensitive diagenetic redistribution. Hg exerted its maximum mobility in the near-surface sediment strata as a component of water-soluble organic matter. Despite the predominance of fulvic acids in extracted humus fractions, humic acids were a much more efficient concentrator for Hg (0-79 vs. 188-233 microg Hg g(-1) C(org), respectively). Nevertheless, the most refractory non-hydrolyzing residue (humin) fraction contained the principal Hg pool in the sediments. Hg content in all the extracted fractions decreased with core depth, thus indicating Hg immobilization as a principal tendency in Hg fate during post-depositional diagenesis.     

Wetland soil and vegetation bismuth content following experimental deposition of bismuth pellets

Bismuth pellets have been approved as a non-toxic alternative to lead pellets in Canada since 1997 but, to our knowledge, there is little literature for soil and vegetation bismuth content in areas of bismuth pellet deposition. The present study addresses this shortcoming by measuring wetland soil and vegetation bismuth content following experimental deposition of bismuth pellets under ambient and experimentally increased acidic deposition conditions. We manipulated 24 plots in a fully factorial design (bismuth shot x soil acidification) in a south-eastern Ontario freshwater wetland during 1999-2003. Soil pH (range 6.5-7.3) increased significantly (p = 0.001) during the experimental period but there were no significant differences amongst treatments (p = 0.79). Significantly (p < 0.05) greater bismuth concentrations were measured in soil receiving bismuth pellets (mean +/- SE, n = 6; with acidification = 2.55 +/- 1.02 microg Bi g(-1) dry mass [DM]; without acidification = 6.40 +/- 2.23 microg Bi g(-1) DM) compared to plots that were not seeded with bismuth pellets (without acidification = 0.42 +/- 0.09 microg Bi g(-1) DM; with acidification = 0.39 +/- 0.10 microg Bi g(-1) DM). Nevertheless, bismuth levels in 20 of 24 aboveground tissue samples from the Carex lacustris-Agrostis scabra community were below detection levels (0.057 microg Bi g(-1) DM); the other samples ranged from 0.065 to 0.095 microg Bi g(-1) DM, similar to global background levels. Primary productivity in plots receiving bismuth pellets and soil acidification was not significantly (p = 0.15) different to vegetation in plots that were not manipulated. The results suggest bismuth mobilization from bismuth pellets into soil but not to aboveground vegetation.     

Ecological restoration of mined-out areas of dry tropical environment, India

The objective of the present study was to evince the long-term changes after natural revegetation and experimental revegetation of the coal mine spoils with respect to total plant biomass, available plant nutrients, nitrogen transformation and microbial biomass N (MBN) in dry tropical environment of India. Total plant biomass (above- and below-ground), plant available nitrogen, soil nitrogen mineralization and microbial biomass N (MBN) were studied for 2 years in 5 and 10 years old naturally vegetated and revegetated coal mine spoils, and dry tropical forest ecosystem of India. In forest ecosystem, the above ground biomass values ranged from 3,520 to 3,630 kg ha(-1) and belowground from 6,280 to 6,560 kg ha(-1). Plant available nitrogen ranged from 16.76 to 23.21 microg g(-1), net N-mineralization from 9.8 to 48.53 microg g(-1) month(-1) and MBN from 26.4 to 80.02 microg g(-1). In naturally revegetated mine spoil, the above ground biomass values ranged from 1,036 to 1,380 kg ha(-1) and belowground from 2,538 to 3,380 kg ha(-1). Plant available nitrogen ranged from 7.33-17.14 microg g(-1), net N-mineralization from 3.1 to 12.46 microg g(-1) month(-1) and MBN from 14.2 to 35.44 microg g(-1). In revegetated mine spoil, the above ground biomass values ranged from 1,224 to 1,678 kg ha(-1) and belowground from 2,870 to 4,130 kg ha(-1). Plant available nitrogen ranged from 9.4 to 18.83 microg g(-1), net N-mineralization from 4.2 to 16.2 microg g(-1) month(-1) and MBN from 21.6 to 42.6 microg g(-1). The mean plant biomass values in 5 and 10 years mine spoils was lower compared to forest ecosystem by 2.5 and 2 times, respectively. N-mineralization value in 5 year mine spoil was 3.5 times lower and in 10 years mine spoil 2 times lower compared to forest ecosystem. The MBN value was about 2 times lower in both 5 and 10 year mine spoils compared to native forest. MBN was positively related to the re-vegetation age of the mine spoil.     

Environmental contaminants in male river otters from Oregon and Washington, USA, 1994–1999

This study reports hepatic concentrations and distribution patterns of select metals, organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in 180 male river otters (Lontra canadensis) collected from Oregon and Washington, 1994-1999. Seven regional locations of western Oregon and Washington were delineated based on associations with major population centers, industry or agriculture. Cadmium (Cd) was not found above 0.5 microg g(-1), dry weight (dw) in juveniles, but increased with age in adults though concentrations were generally low (nd-1.18 microg g(-1), dw). Regional geometric means for total mercury (THg) ranged from 3.63 to 8.05 microg g(-1), dw in juveniles and 3.46-12.6 microg g(-1) (dw) in adults. The highest THg concentration was 148 microg g(-1), dw from an apparently healthy adult male from the Olympic Peninsula of Washington. Although THg increased with age in adult otters, the occurrence of the more toxic form methylmercury (MeHg) was not evaluated. Mean OC and PCB concentrations reported in this study declined dramatically from those reported in 1978-1979 from the lower Columbia River. Organochlorine pesticide and metabolite means for both juvenile and adult river otter males were all below 100 microg kg(-1), wet weight (ww), with only DDE, DDD and HCB having individual concentrations exceeding 500 microg kg(-1), ww. Mean SigmaPCB concentrations in both juvenile and adult male otters were below 1 microg g(-1) for all regional locations. Mean juvenile and adult concentrations of non-ortho substituted PCBs, PCDDs and PCDFs were in the low ng kg(-1) for all locations studied.     

Atmospheric-particulates-bound mercury Hg(p) study at five characteristic sampling sites in Taiwan

The main purpose for this study is to observe the seasonal and month variations for particulates-bound mercury Hg(p) in total suspended particulates (TSP) concentration, dry deposition at five characteristic sampling sites during years of 2009-2010 in central Taiwan. The results show that the highest and lowest monthly average particulates-bound mercury Hg(p) concentrations in TSP were occurred in Dec. and Oct. at Gao-mei (wetland), Chang-hua (downtown) and He-mei (residential) sampling site. In addition, the results show that the highest and lowest monthly average particulates-bound mercury Hg(p) dry deposition was occurred in Feb. and Oct. at Quan-xing (industrial) sampling site. This study reflected that the mean highest particulates-bound mercury Hg(p) concentrations in TSP and mean highest particulates-bound mercury Hg(p) dry deposition were occurred at Gao-mei (wetland) and Quan-xing (industrial). However, the mean lowest particulates-bound mercury Hg(p) concentrations in TSP and mean lowest particulates-bound mercury Hg(p) dry deposition were also occurred at Gao-mei (wetland). Regarding seasonal variation, the order of mean-particulates-bound mercury Hg(p) concentrations in TSP in winter and spring were Gao-mei (wetland) > Quan-xing (industrial) > Bei-shi (suburban/coastal) > Chang-hua (downtown) > He-mei (residential). Finally, the order of mean-particulates-bound mercury Hg(p) dry deposition in fall, spring and summer were Quan-xing (industrial) > Bei-shi (suburban/coastal) > Chang-hua (downtown) > He-mei (residential) > Gao-mei (wetland).     

Speciation and mass-balance of mercury from pulverized coal fired power plants burning western Canadian subbituminous coals

This report summarizes the results of a study carried out on six pulverized coal-fired power plants in western Canada burning subbituminous coal for the mass-balance and speciation of mercury. The main objectives of this study were to: determine the total gaseous mercury (TGM) emitted from stacks of power plants using the Ontario Hydro method; identify the speciation of emitted mercury such as metallic (Hg(0)) and gaseous elemental (GEM) mercury; and perform mass-balance calculations of mercury for milled-coal, bottom ash, electrostatic precipitators (ESP) fly ash and stack-emitted mercury based on three tests. Sampling of mercury was carried out using the Ontario Hydro method and mercury was determined using the USEPA method 7473 by cold vapor atomic absorption (CVAAS). The sample collection efficiencies confirmed that both oxidized and the elemental mercury had been successfully sampled at all power plants. The total gaseous mercury emitted (TGM) is 6.95-15.66 g h(-1) and is mostly in gaseous elemental mercury (GEM, Hg(0)) form. The gaseous elemental mercury is emitted at a rate of 6.59-12.62 g h(-1). Reactive gaseous mercury (RGM, Hg(2+)) is emitted at a rate of 0.34-3.68 g h(-1). The rate of emission of particulate mercury (Hg(p)) is low and is in the range 0.005-0.076 g h(-1). The range of mass-balances for each power plant is more similar to the variability in measured mercury emissions, than to the coal and ash analyses or process data. The mass-balance calculations for the six power plants, performed on results of the three tests at each power plant, are between 86% and 123%, which is acceptable and within the range 70-130%. The variation in mass-balance of mercury for the six power plants is mostly related to the variability of coal feed rate.