Average Mercury Concentration Research Articles

Mercury in saliva, milk, and hair of nursing mothers in southeastern Iranian mothers: levels, distribution and risk assessment.

This research is on lactating mothers in the city of Chah Bahar in Iran. This descriptive-analytical and questionnaire study selected a random sample of 80 mothers to examine mercury levels in their hair, milk, and saliva. The average concentration of mercury in milk, hair and saliva of mothers was 1.23 ± 0.48µg/l, 1.81 ± 0.55µg/g and 1.10 ± 0.63µg/l, respectively. There was a significant correlation between mercury levels in mothers saliva and hair. Still, only a weak correlation was found between mercury levels in milk and hair, and milk and saliva, possibly associated with the high lipid content in milk. The number of children and length of the mother's pregnancy were related to the amount of mercury in the mother's milk. The number of teeth filled with amalgam, consumption of fish and marine products, consumption of fruit, and infant's weight at birth were also associated with the amount of mercury in breast milk. Chewing gum, fish consumption, infant's birth weight, weight, and length of pregnancy were among the factors associated with the amount of mercury in mothers' saliva. The mercury concentration in milk exceeded the WHO (1.4-1.7µg/g) normal level in 8.5%mothers, and hair mercury was found in 12.5% mothers. It should be kept in mind that any amount of mercury can be harmful.

Presence of Mercury in an Arid Zone of Mexico: A Perspective Based on Biomonitoring of Mammals from Three Trophic Guilds.

Mercury (Hg) has been extensively studied due to its impact on the environment and health, but its effects on wild mammal populations are still poorly known. Therefore, the use of biomonitors has gained importance. Our objective was to report and compare, for the first time, the amount of mercury in small mammals belonging to three trophic guilds and to provide an initial toxicology perspective in the Mezquital Valley, a critically polluted area of Central Mexico. We quantified total Hg from the hair and liver of a nectarivorous bat (Leptonycteris yerbabuenae), an insectivorous bat (Corynorhinus townsendii) and a granivorous mouse (Peromyscus melanophrys) using atomic absorption spectrometry during the dry and rainy seasons. We compared the mercury concentrations between seasons, species and matrices. In all species, the average mercury content was higher in hair than liver, and there was no correlation between matrices. There was no difference in mercury content among species. Hg concentrations in the livers of P. melanophrys and C. townsendii were lower during the dry season than the rainy season, suggesting a seasonal decline in mercury availability. All of the values detected were below the neurotoxicity threshold reported in small mammals (10 ppm); however, we propose constant monitoring of Hg in their environment and confirm the utility of these species as biomonitors.

RETRACTED: Assessing Mercury Contamination Levels in the Sediments of Two Pyrenean Lakes

Mercury, a trace metal, is a persistent environmental pollutant that can be detected even in remote regions, including high-mountain lakes. This study examined mercury concentrations in the sediment of two lakes in the French Pyrenees, the Legunabens and Labant lakes. Sediment samples were collected using a Hon-Kajak Sediment Corer, and mercury concentrations were measured following the EPA 7473 method with a direct mercury analyzer (DMA-80). Mercury levels reached up to 283 ng g−1 in the Legunabens lake and up to 110 ng g−1 in the Labant lake, possibly linked to the mining history of the Ariège department and atmospheric deposition from distant sources. These findings indicate significant contamination, ranging from an 8% to 42% probability of generating adverse biological effects according to Canadian standards, and approximately 90% higher concentrations compared to average mercury concentrations in other Pyrenean lakes. Such contamination poses potential risks to aquatic life and the environment due to mercury’s toxicity and bioaccumulation in microorganisms.

Effect of the stabilization process of sewage sludge on the mercury content of municipal sewage sludge

Sewage sludge, the amount of which is increasing every year, must be disposed of on the one hand, and on the other hand it makes a pretty good alternative fuel. However, due to the high mercury content of sewage sludge, its use for energy purposes requires further research. The effect of the technological process of sewage sludge treatment on the mercury content of this end product of wastewater treatment is not fully understood. Therefore, the present study examined 17 sewage sludges from municipal wastewater treatment plants in Lower Silesia for energy properties and mercury content before and after the following technological processes: autothermal aerobic stabilization at temperatures above 50 °C (ATSO), aerobic separated stabilization at effluent temperature (KTSO), separated digestion at ambient temperature (OKF) and separate digestion at 37 °C (WKF). The study showed that the mercury content ranged widely from 0.47 to 6.05 mg/kg Hg, indicating several times higher atmospheric emissions than when using conventional fuels. Among the sewage sludge samples tested, there were samples with very high mercury content, significantly different from the average mercury content of the sludge from the same process line. On this basis, it is concluded that the sewage sludge disposal process leads to the formation of significantly heterogeneous material.Sludge stabilization processes (ATSO, KTSO, OKF, and WKF) increase the mercury content of sewage sludge.

Health-risk assessment of mercury in main market-sold foods in the Pingliang region of Gansu province, China, from 2013 to 2021

In the present study, we analyzed mercury concentrations in 742 samples across five main food categories from 2013 to 2021 using direct mercury analysis (DMA) to understand mercury pollution in major market-sold foods in the Pingliang region of Gansu Province and assess the health risks of mercury dietary exposure in adults. Health risks of adult dietary exposure were assessed through deterministic evaluation. Total mercury content ranged from non-detectable (ND) to 0.13 mg/kg, with a detection rate of 90.70% (673/742), the highest detection rates being in fresh edible mushrooms and nuts. The overall exceedance rate was 0.13% (1/742), with one sample of fresh edible mushrooms exceeding the regulatory limit for total mercury content. Additionally, we incorporated the average mercury content and consumption levels of meat and seafood from regions geographically close to Pingliang, as reported in the Fifth National Total Diet Study, to calculate the Estimated Daily Intake (EDI) by a deterministic evaluation. For adult males, the exposure was 0.120 μg/(kg BW), while for adult females, it was 0.141 μg/(kg BW). Both values are significantly lower than the provisional tolerable weekly intake (PTWI) of 4 μg/(kg BW) established by JECFA in 2010, indicating that the total mercury concentration from food intake does not pose a significant health risk to the residents of the Pingliang area. These findings offer valuable scientific data to inform food safety regulations in the region and can serve as a benchmark for future mercury pollution risk assessments in other locations.

A novel approach to assessing the joint effects of mercury and fish consumption on neurodevelopment in the New Bedford Cohort

Abstract Understanding health risks from methylmercury (MeHg) exposure is complicated by its link to fish consumption, which may confound or modify toxicities. One solution is to include fish intake and a biomarker of MeHg exposure in the same analytical model, but resulting estimates do not reflect the independent impact of accumulated MeHg or fish exposure. In fish-eating populations, this can be addressed by separating MeHg exposure into fish intake and average mercury content of the consumed fish. We assessed the joint association of prenatal MeHg exposure (maternal hair mercury level) and fish intake (among fish-eating mothers) with neurodevelopment in 361 children aged 8 years from the New Bedford Cohort (New Bedford, Massachusetts; born in 1993-1998). Neurodevelopmental assessments used standardized tests of IQ, language, memory, and attention. Covariate-adjusted regression assessed the association of maternal fish consumption, stratified by tertile of estimated average fish mercury level, with neurodevelopment. Associations between maternal fish intake and child outcomes were generally beneficial for those in the lowest average fish mercury tertile but detrimental in the highest average fish mercury tertile, where, for example, each serving of fish was associated with 1.3 fewer correct responses (95% CI, −2.2 to −0.4) on the Boston Naming Test. Standard analyses showed no outcome associations with hair mercury level or fish intake. This article is part of a Special Collection on Environmental Epidemiology.

Identification Of Mercury Levels in The Urine of Gold Processing Workers in Krueng Sabee Aceh Jaya District

Teknik amalgamation by involving mercury in the gold processing process is still widely used by gold miners in Indonesia, such as those in Paya Seumantok Village, Krueng Sabee District, Aceh Jaya Regency, so that it has the potential to threaten the health of workers. Therefore, in this study, mercury levels in the urine of workers at the gold processing plant in Paya Seumantok Village were identified. The sample in this study was the urine of all workers at the gold processing site, totaling 10 workers, the Analysis of mercury levels in the urine was carried out using the AAS instrument. Based on the Analysis results from 10 urine samples, 3 samples did not detect the presence of mercury, while the other 7 samples were identified as mercury. The average mercury content contained in the urine of gold processing workers is 5.80 μg / L, the minimum concentration of mercury in the urine of the people who have been successfully detected is 0.00 μg / L. In comparison, the maximum or highest concentration is 33.88 μg / L. Average mercury content in worker urine does not exceed the threshold based on the threshold value set by Human Biomonitoring (HBM) of 7 μg /L, however, from the results of the Analysis, several samples of worker urine had a urine content exceeding the threshold.

Soil and Urine Mercury Levels in Secocha: A Case Study of Artisanal and Small-Scale Gold Mining in Peru

In recent decades, artisanal and small-scale gold mining (ASGM) has spurred population and economic growth in the small rural communities in which it is located, along with causing contamination of the soil, air, and water with grave effects on human health due to the uncontrolled use of mercury for gold processing activities. This study analyzes the levels of mercury in Secocha, an ASGM community in Arequipa, Peru. A total of 44 soil samples were taken from two ASGM commercial-extractive zones (n = 18) and non-processing urban zones (n = 26). Soil mercury analysis with atomic absorption spectrometry revealed average mercury levels of 86.11 mg/kg in commercial-extractive zone I, where ore processing has occurred for about 17 years, and mercury levels of 43.81 mg/kg in commercial-extractive zone II, where processing has occurred for about 7 years. In the urban zone, the average mercury level was 9.53 mg/kg. The average mercury concentrations for each zone exceed the relevant environmental quality standards established by the Peruvian Ministry of the Environment. In addition, urine samples were obtained from 15 miners and 15 people from the general urban population (non-miners). The average mercury level in the urine of miners was 7.04 µg/L, and in the urine of non-miners it was 0.49 µg/L. In both cases, the mercury urine level did not exceed the limits established by WHO and the Peruvian Ministry of Health, though miners’ elevated levels do raise concerns.

Measuring Total Mercury Level in Local Food Fish Bangamary (Macrodon ancylodon) in Guyana

This research conducted in 2019 at the University of Guyana investigated the content of methylmercury in local food fish Macrodon ancylodon locally known as Bangamary. A total of 24 samples of M. ancylodon was purchased from the Meadow Bank Wharf in Guyana for analysis of total mercury level. Additionally, the size frequency at which mercury concentration is the highest was also evaluated. The results indicated that total mercury concentration in each sample of M. ancylodon was less than 0.5 mg/kg. With an average total mercury content of 0.10 mg/kg, adults had the greatest total mercury content, followed by juveniles (0.06 mg/kg) and young (0.02 mg/kg). This may be attributed to the carnivorous diet of M. ancylodon and the fact that the fish species is usually captured in the estuarine regions of the Demerara and Essequibo Rivers. These waterways are linked to mining areas in Guyana's interior region that discharge mercury contaminated water, which could be the reason why mercury is bioaccumulating in the tissue of the Bangamary.

Potential Bioabsorbent Extract of Skin and Leaves Ananas Comosus on reduction of Copper, Mercury, and Lead in Anadara granosa

Kenjeran sea waters were polluted by several types of heavy metals such as copper (0.015mg/L), lead (0, 0036 mg/L), and mercury (0.001mg/L). Consuming Anadara granosa containing heavy metals exceeding the standard is very dangerous. The purpose of this study was to determine the effect of pineapple leaf and peel extract on reducing levels of copper, lead, and mercury in Anadara granosa in Kenjeran. Methods: Treatment without giving pineapple leaf and peel extract (Control) and treatment with pineapple leaf and peel extract using 0% and 3% concentrations. The results of heavy metal levels were in the form of numbers indicating the content of heavy metal levels in Anadara granosa determined in mg/kg using AAS. Results: The average copper concentration of 0% was 5.037mg/kg, and the 3% concentration was 2.563mg/kg, the average lead concentration at 0% concentration was 2.4333mg/kg and the concentration of 3% is 1.4433mg/kg, the average mercury concentration of 0% is 0.963mg/kg, and the concentration of 3% is 0.323mg/kg (4) Conclusion: there is an effect of pineapple peel and leaf extract on the decrease in copper levels by 50.88%, lead levels by 59%, and 33.54% decrease in mercury levels.

Mercury in the feathers of Golden eagle (Aquila chrysaetos) from Western Carpathian, Slovakia

In this study, mercury (Hg) concentrations were detected in feathers of golden eagle (Aquila chrysaetos), a bird that typically inhabits alpine and forest areas. The mercury rates in feathers were compared in two groups of eagles: first, estimated home range (breeding, hunting, etc.) was located only in forest and lowland meadow habitats; second, the home range also included alpine habitats—rocks and meadows. Consequently, mercury concentration based on the feather typology were observed and the mercury levels in feathers were also compared among different Slovak Western Carpathian districts. It was found that there was no significant difference between groups classified by elevation level, which we attribute to the fact that eagle hunting territories are broad, so that alpine-dwelling and forest-dwelling eagles do not only reflect the pollution of the environments they typically inhabit. Non-significant differences were found also within different feather types, which means that the type of feather is not crucial for tracking mercury in eagle feathers. As the measurement of feather appears to be a simple and non-invasive method, the detection of non-significant differences in diverse types of golden eagle feathers provides useful knowledge for the future environment monitoring. The average mercury concentration measured in eagle samples was lower than the mercury concentration causing health complications among birds of prey. Our assumption that due to past mining activity in the Spiš region, the highest concentration in this region would be observed was confirmed.

Mercury concentrations and potential methylation rates in Lake Erie

Abstract Little is known about external and internal loading and cycling of bioaccumulative methylmercury in Lake Erie, despite the lake having a world-renowned sport fishery. During the summer/early fall of 2018 to 2021, concentrations and fluxes of total mercury and methylmercury in the water column were examined near the Detroit and Maumee River discharges into western Lake Erie, as well as the junction between Sandusky Bay and central Lake Erie. Average unfiltered total mercury concentrations were similar near the Detroit River (5.4 ± 0.8 pM) and Sandusky Bay inputs (5.3 ± 0.9 pM), which were less than half of those near the Maumee River mouth (11.6 ± 2.8 pM). Similarly, unfiltered methylmercury concentrations near the Detroit River (0.29 ± 0.09 pM) and Sandusky Bay inputs (0.24 ± 0.06 pM) were less than half of those near the Maumee River mouth (0.63 ± 0.21 pM). Potential specific mercury methylation rates measured in central Lake Erie were 0.062 ± 0.027 day-1, 0.045 ± 0.012 day–1 near the Sandusky Bay input, and 0.031 ± 0.006 day–1 at the Detroit River input (Maumee Bay was below detection; rates were not different; Tukey, p >0.87). Compared to previous work, total mercury concentrations in the western basin observed in this study indicate a decrease of about 3.3% yr–1, which may reflect positive impacts of state, provincial, and national legislation (U.S. National Clean Water Act 1990, Ohio Clean Air and Water Act 2004, Ontario Clean Water Act 2006). However, methylmercury concentrations have increased in western Lake Erie from 2010 to 2019, which may reflect the impact of legacy mercury pollution.

Assessment of Soil Pollution by Heavy Metals in the Market Gardening Areas of Korsimoro

The aim of this study was to assess heavy metal soil pollution in market garden areas in the commune of Korsimoro. The analysis focused mainly on zinc (Zn), nickel (Ni), chromium (Cr), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co), arsenic (As) and mercury (Hg). Composite samples of soil labels s1 to s21 were taken from the market garden site around the dam at a depth of 0-20 cm. A total of 21 soil samples were taken. The soil samples were analysed using inductively coupled plasma mass spectrometry (ICP/MS) at the Bureau of Mines and Geology of Burkina Faso laboratory (BUMIGEB).
 The enrichment factor (EF), contamination factor (CF), géoaccumulation index (Igeo) and pollution load index (PLI) were determined from the metal concentrations obtained.
 The average concentrations of heavy metals vary as follows:
 Cd > Co > Cr > Zn > Ni > Cu > Hg > Pb > As.
 The average concentrations of cadmium (587.039mg/kg±20.546), mercury (29.048mg/kg±20,647), nickel (60.037 mg/kg±14,615) and cobalt (575.956mg/kg±66,693) exceed the WHO limit values for agricultural soils.
 The calculated CF values show very high contamination of Co, Cd and Hg, considerable contamination of Cu, Cr, Zn, Ni and As, and no contamination of Pb.
 The EF values show very severe enrichment for cobalt (Co), followed by overall extremely severe enrichment for cadmium (Cd) and mercury (Hg).
 The calculated Igeo indicates extreme cadmium, mercury and cobalt contamination.
 The calculated PLI values are all greater than one. These results show that all the soils are polluted.
 The index determination approach makes it possible to predict the extent of soil pollution by the heavy metals considered in our study.

In Search of Mercury Lost from Sediments in a Previously Contaminated Coastal Area, Harboøre Tange, Denmark

Concentrations of mercury in sediment and benthic invertebrate fauna of Nissum Broad, North-western Jutland, Denmark were investigated. The western coast of Nissum Broad is Harboøre Tange, along which heavy mercury contamination - caused by discharge from production of mercury containing seed dressers in the 1950 and 1960s – was documented in the 1980s. Recent investigations showed marked decreases in mercury contamination in the near shore sediments along Harboøre Tange since the 1980s and the present investigation was initiated to learn if the loss of mercury from Harboøre Tange had led to an increased mercury contamination in the neighbouring marine area, Nissum Broad. Mercury concentrations in the surface sediment correlated with the content of organic matter and the slope of the regression is a good indicator for the degree of mercury contamination. Average mercury concentrations in the upper 5 cm of the sediments ranged between 0.9 and 71 ng g− 1 dry weight (dw) with only 1 station exceeding the Background Assessment Concentration of 70 ng g− 1 dw. Average mercury concentrations in blue mussels Mytilus edulis (169–260 ng g− 1 dw) and periwinkles Littorina littorea (66–203 ng g− 1 dw) exceeded those in uncontaminated areas and the Environmental Quality Standard of approximately 100 ng g− 1 dw. Present sediment mercury concentrations in Nissum Broad are approximately half of what they were in the 1980s, rendering it unlikely that mercury lost from Harboøre Tange has been deposited there. Sediment and organism concentrations did not show any correlation.

Small mammals as a bioindicator of mercury in a biodiversity hotspot – The Hengduan Mountains, China

Due to toxicities, capacities for long-range transportation, bioaccumulation, and biomagnification, mercury (Hg) presents a unique concern to wildlife in remote ecosystems, including “the roof of the world”. Large carnivorous predators are thought to be exposed to elevated Hg due to their high trophic positions, but the direct assessment for Hg contamination is a challenge. Given the poorly understood Hg exposure in these carnivores, establishing a reliable and straightforward assessment would be essential to identify targeted species at Hg exposure risk for effective conservation, particularly in fragile biodiversity hotspots. Small mammals are abundant and serve as prey for large top predators. Combined with local observations, we provided an assessment to estimate the daily Hg exposure via consumption of small mammals for large carnivorous mammals recorded in the Hengduan Mountains, a world biodiversity hotspot, China. Within an altitude span from 2043 to 4251 m a.s.l., the average topsoil total mercury concentration (hereafter [THg]) was 44.65 ± 25.80 μg/kg (mean ± sd; 10.54 – 135.15 μg/kg, n = 41), while the hair [THg] in small mammals was 104.66 ± 91.96 μg/kg (mean ± sd; 7.73 to 385.70 μg/kg, n = 13). Furthermore, the daily intake of Hg was calculated among the 22 investigated/historical-recorded carnivore mammals belonging to 5 families. We found a large variance in daily intake of Hg via small mammals: Felidae (median: 205.93 μg/day) > Ursidae (135.02 μg/day) > Canidae (92.92 μg/day) > Viverridae (19.88 μg/day) > Mustelidae (7.18 μg/day). Specifically, Tiger Panthera tigris was found with the highest Hg daily intake (1701.39 μg/day) via consuming small mammals, while species belonging to Mustelidae generally have low Hg daily intake (<3 μg/day). This study provides a feasible approach to identifying species at environmental Hg risk in this fragile remote high-elevation region. The limitations and future improvements were discussed.

Effects of Age, Fulton's Condition Index (K) and Muscle Fat on Total Mercury Content in Raw, Pre-Canning and Canned Samples of Atlantic Bluefin Tuna (Thunnus thynnus).

A total of 30 samples of Atlantic bluefin tuna were analysed for total mercury concentration. Relationships between total mercury content and age, Fulton's condition index (K) and fat content were statistically evaluated. The effect of muscle status (raw, pre-canning, canned) on mercury content was also investigated. The average total mercury content was: 1.185 ± 0.662 mg/kg in raw, 1.481 ± 0.893 mg/kg in pre-canning and 1.393 ± 0.882 mg/kg in canned samples, respectively. Canning promotes a statistically significant increase in the concentration of mercury. The weight of fish, K and fat content are useful tools to estimate the mercury accumulation in Atlantic bluefin tuna. The results of the present study represent a contribution to the assessment of the EU mercury levels in Atlantic bluefin tuna.

МОНИТОРИНГ ФОНОВОГО СОДЕРЖАНИЯ РТУТИ В БИОСИСТЕМЕ И ОРГАНИЗМЕ ДЕТСКОГО НАСЕЛЕНИЯ НИЖНЕГО ТЕЧЕНИЯ РЕКИ АМУР

Study Objective: to determine the mercury content in the body of children as well as in soil and river fish to assess the level of risk of adverse effects on a human body. Study Design: analytical observational, cross-sectional study. Materials and Methods. A quantitative analysis of mercury in hair of conditionally healthy children (n=62), the upper layer of soil (n=15) taken on the territory of the former cellulose and cardboard manufacturing plant (CCMP) located in one of the cities of the Khabarovsk region and in fish (n=27) living in the Amur river downstream was performed using inductively coupled plasma mass spectrometry. The relationship between the level of mercury and cognitive abilities of adolescents was studied. Study Results. An average content of mercury in the upper layer of the soil was 0.85 mg/kg; with the maximum value of the mass fraction of mercury 1.25 mg/kg, the mercury concentration was 8.5-12.5 times higher than the Russian background value. When determining the concentration of mercury in the fish muscle tissue – the main source of organic mercury for children, it was revealed that the content of mercury in the tissues of predatory fish ranged from 0.47-0.52 mg/kg, while the mercury level in non-predatory fish was 0.24 mg/kg. The average mercury content in hair of adolescence was 0.47±0.05 mg/kg and 0.19±0.02 mg/kg in 6-7-year-old children, and it did not exceed the critical level. Conclusion. It was found out that the content of mercury in the soil had significantly decreased compared to 2009, but the level remains above the Russian background value. Mercury content in part of the fish muscle living in the Amur River downstream was higher in predatory species. The concentration of mercury in the children organism permanently living on the territory of anthropogenic pollution did not exceed the threshold level, but the detected background values may have contributed to concentration decrease.

Distribution of Mercury in Drained Peatlands as the Effect of Secondary Transformation of Soil Organic Matter

Peat organic soils play a major role in the accumulation of soil organic matter (SOM) and the mercury (Hg) cycle. Large mercury resources in peatlands can be a source of methylmercury for many decades and centuries, even if deposition is significantly reduced. The organic matter of peatland soils drained for agricultural use is subject to secondary transformation, which may affect the accumulation and resources of mercury. The aim of our work is to assess the secondary transformation of organic matter in the soils of drained peatlands of the temperate climate zone and to examine whether it affects mercury resources and profile distribution in organic soils. Field research was conducted in peatlands located in eastern Poland. In the present study, evaluation of secondary transformations occurring after drainage was based on observations of soil morphological characteristics, physical and chemical properties as well as fractional composition of organic matter of the identified soil horizons (to depth 70 cm). Standard cold vapor atomic absorption spectrometry (CV-AAS) was used to measure the total mercury content. In our research, we found a significant effect of the secondary transformation of organic matter occurring in drained peatlands of the temperate climate zone on the total mercury content and stock in soils. The highest content and differentiation of mercury occurred in murshic horizons (up to a maximum depth of 43 cm). The average mercury content of the distinguished soil horizons is grouped in the following series (in μg kg−1): M1 (212.0) &gt; M2 (182.8) &gt; M3 (126.3) &gt; Pt (84.9). The mercury stock, up to a depth of 70 cm in the tested soils, ranged from 17.5 to 39.6 mg m−2. As much as 82.2% of soil mercury was found in the upper murshic horizons. We found strong correlations between soil properties characteristically variable in the secondary transformation process and total mercury content. The increased content of humic substances in murshic horizons caused a significant increase in the total mercury content. Our research is of great importance for soil monitoring, as the amount of determined mercury was greatly influenced by the depth of sampling (up to 25 cm). The results of the research should be taken into account when planning the restoration of peatlands of the temperate climate zone. There is a potential risk that elevated mercury concentrations in the upper murshic horizons may be a source of methylmercury for a long period of time. In peat soils with a high concentration of mercury, the risk of contamination with this toxic metal should be determined before re-irrigation.

Enrichment of Sulfate, Acidity and Mercury in Native outcropcoal, Southwest China.

The coal found in the Longtan Formation of the Late Permian is widely distributed in Southwest China, including the northwestern Guizhou, southeastern Sichuan, and northern Yunnan regions. This coal typically has a high sulfur content. Eighty-two coal samples were collected from the coal strata in 11 counties spanning this area, including underground mine coal, native outcrop coal and man-made outcrop coal. The mercury, total fluorine, total sulfur, and sulfate contents and pH values were determined. The results showed that the average mercury content in native outcrop coal was 2233ng/g, whereas that in underground mine coal was 306ng/g, and the relative enrichment factor could reach 6.6. There was no significant difference in the total fluorine content among the three types of coals; furthermore, the total sulfur content in native outcrop coal and man-made outcrop coal was higher than that in underground mine coal because of the local policy, which strictly prohibits the mining of high-sulfur coal. Native outcrop coal is acidic, with a total average pH of 3.54 and an average sulfate content as high as 13,390μg/g. In contrast, underground coal is almost neutral (average pH 7.33), with a low sulfate content (average 3221μg/g). These characterizations indicate that native outcrop coal has been subjected to long-term weathering and the mercury enrichment is likely due to migration, oxidation, and precipitation of Hg from the underground coal seam and enriched in loose and pulverized coal particles. Further investigation is needed to determine whether other outcrop areas are affected by this phenomenon.

Characteristics of Mercury Fluxes between Soil and Air in the Farming-Pastoral Ecotone of Songnen Grassland

In order to understand the characteristics and influencing factors of surface release fluxes in the typical agro-pastoral mosaic region of the Songnen grasslands of northern China, this study selected two sample plots to, respectively, represent the L. chinensis covered grassland (L), and the Z. mays covered fields (Z) in the Waizi area of Changling County, with western Jilin Province as the study area. This study investigated the atmospheric mercury (Total Gaseous Mercury (TGM)) concentrations, surface soil mercury concentrations, the gaseous elemental mercury exchange fluxes, and related environmental factors. The results showed that the TGM concentrations in two sample plots in the study area were basically the same during the summer and autumn months, but were higher in summer than in autumn, and there was a clear diurnal pattern. The average mercury concentrations in the surface soil were also higher in summer than in autumn. Furthermore, the surface soil has a clear mercury release process, and the mercury release were higher in the sheep grass field than the maize field during the same season. The mercury release fluxes in each site within the ecotone were related to the solar radiation and soil temperature values, and the effects of them on the soil mercury release were independent from one another.