Antimony, arsenic and mercury in the aquatic environment and fish in a large antimony mining area in Hunan, China

Antimony (Sb) has received increasing attention recently due to its toxicity and potential human carcinogenicity. In the present work, drinking water, fish and algae samples were collected from the Xikuangshan (XKS) Sb mine area in Hunan, China. Results show that serious Sb and moderate arsenic (As) contamination is present in the aquatic environment. The average Sb concentrations in water and fish were 53.6 ± 46.7 μg L^− 1 and 218 ± 113 μg kg^− 1 dry weight, respectively. The Sb concentration in drinking water exceeded both Chinese and WHO drinking water guidelines by 13 and 3 times, respectively. Antimony and As concentrations in water varied with seasons. Fish gills exhibited the highest Sb concentrations but the extent of accumulation varied with habitat. Antimony enrichment in fish was significantly lower than that of As and Hg.     

Environmental impacts and metal exposure of aquatic ecosystems in rivers contaminated by small scale gold mining: the Puyango River basin, southern Ecuador.

Gold mining in the Portovelo-Zaruma district in southern Ecuador is causing considerable environmental impacts; the most important ones are related to the discharge of cyanide, mercury and metal rich tailings into rivers of the Puyango catchment area. Cyanide and metal levels in rivers regularly exceed environmental quality criteria. The contamination impacts biodiversity, with cyanide causing a direct lethal effect on biota close to source and metal contaminants considerably reducing aquatic biodiversity further downstream. It is shown that the prevailing neutral or slightly alkaline conditions of the rivers ensure that metals are mainly associated with sediment. However, elevated metal levels in bottom living larvae collected from contaminated sites suggest that these sediment bound metals are readily bioavailable. Leaching experiments indicate that the relative ease by which metals are taken up by larvae is related to the speciation of sediment associated metals. It is further shown that large amounts of metals, which are bound to suspended sediment under ambient pH conditions, enter the dissolved and directly bioavailable state in more acidic conditions. Metal levels in carnivorous fish were found to be modestly elevated only, with the exception of mercury. Mercury levels exceeded 0.5 mg/kg in fish from both contaminated and uncontaminated sites, showing that both methylation and bioaccumulation of mercury are occurring in the Puyango river basin.     

Determination of mercury methylation potentials in the water column of lakes across Canada

A stable isotope technique was used to trace the formation of methylmercury in lake water incubation assays at in situ conditions in five lakes across Canada. Methylation activity was only detected in the anoxic hypolimnia of lakes. The stable isotope was methylated at varying rates between lakes and depths within lakes ranging from 0.56%/day to 14.8%/day. A peak in methylation potential was typically observed just below the oxycline, which decreased with increasing depth. The depth and rates of methylation potential changed seasonally with no methylation activity occurring after fall turnover. A decrease in the sulfate concentration was concomitant with the zone of mercury methylation potential indicating the likely involvement of sulfate reducing bacteria in the methylation process. A simple correlation test between DOC concentrations and methylation rates indicated a positive relationship (r2=0.62; p=0.006; n=27). The demethylation rate constant in the anoxic hypolimnia was less than 0.12 d(-1).     

Arsenic microdistribution and speciation in toenail clippings of children living in a historic gold mining area

Arsenic is naturally associated with gold mineralisation and elevated in some soils and mine waste around historical gold mining activity in Victoria, Australia. To explore uptake, arsenic concentrations in children's toenail clippings and household soils were measured, and the microdistribution and speciation of arsenic in situ in toenail clipping thin sections investigated using synchrotron-based X-ray microprobe techniques. The ability to differentiate exogenous arsenic was explored by investigating surface contamination on cleaned clippings using depth profiling, and direct diffusion of arsenic into incubated clippings. Total arsenic concentrations ranged from 0.15 to 2.1 µg/g (n = 29) in clipping samples and from 3.3 to 130 µg/g (n = 22) in household soils, with significant correlation between transformed arsenic concentrations (Pearson's r = 0.42, P = 0.023) when household soil was treated as independent. In clipping thin sections (n = 2), X-ray fluorescence (XRF) mapping showed discrete layering of arsenic consistent with nail structure, and irregular arsenic incorporation along the nail growth axis. Arsenic concentrations were heterogeneous at 10 × 10 µm microprobe spot locations investigated (< 0.1 to 13.3 µg/g). X-ray absorption near-edge structure (XANES) spectra suggested the presence of two distinct arsenic species: a lower oxidation state species, possibly with mixed sulphur and methyl coordination (denoted As^≈ III_{(-S, -CH3)}); and a higher oxidation state species (denoted As^≈ V_(-O)). Depth profiling suggested that surface contamination was unlikely (n = 4), and XRF and XANES analyses of thin sections of clippings incubated in dry or wet mine waste, or untreated, suggested direct diffusion of arsenic occurred under moist conditions. These findings suggest that arsenic in soil contributes to some systemic absorption associated with periodic exposures among children resident in areas of historic gold mining activity in Victoria, Australia. Future studies are required to ascertain if adverse health effects are associated with current levels of arsenic uptake.     

The Mt. Diwata study on the Philippines 2000-treatment of mercury intoxicated inhabitants of a gold mining area with DMPS (2,3-dimercapto-1-propane-sulfonic acid,Dimaval)

Ninty-five inhabitants of the gold mining area of Mt. Diwata (on Mindanao, Philippines), who were diagnosed to be mercury (Hg) intoxicated, were orally treated with 2 x 200 mg of the chelating agent DMPS (Dimaval, Co. Heyl, Germany) for 14 days in the course of a UNIDO project focusing on mercury pollution abatement. Blood and urine samples before and after treatment, urine after the first application of DMPS and a hair sample were collected and analyzed for Hg. Before and after treatment extensive anamnestic data were collected, medical and neurological investigations and some neuro-psychological tests were performed. In spite of the short time of treatment most of the patients reported a marked improvement of the complaints which were stated by them before the therapy and which are characteristic for a chronic Hg intoxication, for example tremor, loss of memory, sleeplessness, metallic taste, etc. But even in some of the objective neurological parameters like hypo-mimia, Romberg test and tests for tremor/ataxia a statistical significant improvement could be found. Significant improvements could also be found in two neuro-psychological tests (pencil tapping and Frostig). In some cases an extreme high urinary Hg excretion was found under the chelating therapy with DMPS, and by this a distinct reduction of the Hg body burden. Nevertheless, in most cases Hg in blood and urine was not markedly decreased by the treatment. This shows that the duration of the treatment (14 days) was not sufficient for a permanent decrease in Hg. As DMPS excretes Hg mainly through the kidney, it can be concluded that in most cases even after 14 days of treatment there was an ongoing redistribution of Hg from other tissues to the kidney. In conclusion, this study proves that a chelating therapy with DMPS is highly effective even in the case of a mixed chronic and acute intoxication with an unknown combination of Hg vapor, inorganic Hg and organic Hg=methylmercury (MeHg), as characteristic for gold mining areas in the third world. Adverse side effects were rarely reported. Only in one case the medication had to be terminated after the first application due to an allergic skin reaction.     

安徽省全椒县车古尖矿区地质及金异常特征

通过对安徽省全椒县车古尖矿区地质背景的调查,指出有震旦系灯影组和寒武系琅琊山组良好矿源层,强烈褶皱变形、多方向的断裂构造是该区有利成矿部位,并对矿点地质特征及金化探异常特征作了分析.     

Mercury speciation in the Valdeazogues River-La Serena Reservoir system: Influence of Almadén (Spain) historic mining activities

Mercury (Hg) speciation and partitioning have been investigated in a river-reservoir system impacted by the Almadén mining activities, the world's largest Hg district. This study is the first to simultaneously investigate Hg dynamics from above the mining district and into the La Serena Reservoir (3219 Hm³), being the third largest reservoir in Europe and the largest in Spain.Water, sediment and biota were sampled at different seasons during a 2-year study from the Valdeazogues River, which flows east-west from the mining District, to La Serena Reservoir. Simultaneously, a comprehensive study was undertaken to determine the influence of some major physico-chemical parameters that potentially influence the fate of Hg within the watershed.Concentrations of dissolved Hg in water were below 0.14 µg/L, whereas particulate Hg ranged from 0.1 to 87 µg/g, with significant seasonal variation. Total Hg concentrations varied from 7 to 74 µg/g in sediment from the Valdeazogues River, while in sediments from La Serena Reservoir were below 2 µg/g. On the other hand, methyl-Hg reached concentrations up to 0.3 ng/L in water and 6 ng/g in sediment from La Serena Reservoir, whereas maximum concentrations in Valdeazogues River were 5 ng/L and 880 ng/g in water and sediment, respectively. The distribution of Hg species in the Valdeazogues River-La Serena Reservoir system indicated a source of Hg from the mine waste distributed along the river. Total Hg in water was strongly correlated with total dissolved solids and chlorophyll a concentrations, whereas organic carbon and Fe concentrations seem to play a role in methylation of inorganic Hg in sediment. Total Hg concentrations were low in fish from Valdeazogues River (0.8-8.6 ng/g, wet weight) and bivalves from La Serena Reservoir (10-110 ng/g, wet weight), but most was present as methyl-Hg.     

The variations of mercury in sediment profiles from a historically mercury-contaminated reservoir, Guizhou province, China

Baihua Reservoir in Guizhou Province, China, experienced serious Hg contamination from Guizhou Organic Chemical Plant (GOCP) between 1971 and 1997. However, the biogeochemical cycling of Hg in this reservoir is not well studied. Sediment cores were collected in fall 2002, spring 2003 and in spring and fall 2004. THg and MeHg concentrations in all sediment profiles ranged from 0.26 to 38.9 mg/kg and from 0.5 to 27.5 μg/kg (d.w.), respectively. The distribution of THg in sediment cores was characterized by a few peaks, which may correspond to the Hg-containing wastewater discharge history of the GOCP. The average THg concentrations in sediments cores decreased from upstream to downstream due to the deposition of particulate Hg, which is the major form of Hg in water. THg and MeHg concentrations in pore water varied from 6.1 to 5860 ng/L and from 0.3 to 15.4 ng/L, respectively, which were significantly higher than levels in the overlying water column. Average diffusive flux from sediment to water is 1642 and 36 ng/m²/day for THg and MeHg. The spatial distribution of THg in pore water from upstream to downstream showed the same trend as the sediment, but MeHg in pore water did not show a declining pattern with distance from the GOCP. These results suggested that sediments experienced serious contamination of Hg, and the contaminated sediment is an important Hg contamination source to the overlying water.     

Effects of soil conservation measures in a partially vegetated area after forest fires

After forest fires on the east coast of Korea in 2000, some burnt areas were left untreated. Although 80% of the area was reasonably revegetated within 3 months, about 20% of the area was partially vegetated, mainly due to a low density of sprouters and poor growing conditions (eroded soil and steep slopes). Three years after the fires, the effect of soil conservation measures, such as mulching with wood chips, seeding with native plant species and log erosion barriers (LEBs), on runoff and soil erosion were examined using runoff plots. Wood chip mulching greatly reduced runoff and sediment yields and these effects were consistent regardless of the volume of rainfall. Neither seeding nor LEBs reduced runoff and sediment yields. No positive or negative effects of mulching, seeding or LEBs on ground vegetation cover were observed. The ineffectiveness of seeding and LEBs may have been due to the steep slope, the failure of germination and establishment of seeded plants, and the small diameter of logs. Treating hill slopes with mulch should be considered where post-fire regeneration is slow and there is an absence of organic material such as litter.     

Temporal and spatial influences of flooding on dissolved mercury in boreal reservoirs

Dissolved total mercury and methylmercury concentrations ([HgT]D and [MeHg]D, respectively) in natural lakes and reservoirs of varying age (2 months to 69 years) were monitored between 1993 and 1997, during different times of the year and at several sites within the same reservoir. Both HgT-D and MeHgD in flooded environments were significantly greater (Student's t-test, P < 0.001) than those determined for neighbouring lakes, with average concentrations of 2.35+/-0.85 ng(-1) (n = 79) vs. 1.51+/-0.43 ng l(-1) (n = 70) for HgT-D and 0.28+/-0.10 ng Hg l(-1) (n = 87) vs. 0.05+/-0.025 ng Hg l(-1) (n = 30) for MeHgD. Furthermore, the proportion of HgT-D in the methylated form was, on average, nearly four times greater in the reservoir sites as compared with those of the lakes (12% vs. 3.6%). Simple linear regressions used to compare [MeHg]D with nine water quality parameters suggest that factors controlling the presence of MeHgD are not the same in all flooded environments. Overall, our results demonstrate that [MeHg]D are higher in reservoirs as compared with natural lakes and that up to 18 years after reservoir construction [MeHg]D remain elevated as compared with background levels.     

Transfer of mercury and methylmercury along macroinvertebrate food chains in a floodplain lake of the Beni River, Bolivian Amazonia

We have evaluated the mercury and methylmercury transfers to and within the macroinvertebrate communities of a floodplain lake of the Beni River basin, Bolivia, during three hydrological seasons and in two habitats (open water and vegetation belt). Using the stable isotopes δ¹³C and δ¹⁵N, six trophic chains were identified during a previous study. Four are based on only one source: seston, organic matter from the bottom sediment, periphyton and macrophytes. Two are based on mixed sources (seston and periphyton in one case, periphyton and macrophytes in the other). During sampling, we found only one taxon that had surface sediment organic matter as food source and very few taxa whose trophic source was constituted by macrophytes. The periphyton was the most important source during all seasons; it produced the longest chain, with three trophic positions. Whatever the season and trophic source, all collected macroinvertebrates contained methyl mercury and the latter was biomagnified in all trophic chains that we identified. The biomagnification of methylmercury through invertebrate trophic chains accurately reflected the existence and length of these chains. Biomagnification was virtually non-existent in the sediment-based chain, low and restricted to the dry season in the macrophyte-based chain. It was significant in the seston-based chain, but limited by the existence of only two trophic levels and restricted to the wet season. Finally, it was very effective in the periphyton-based chain, which offers the highest rate of contamination of the source but, above all, the largest number of trophic levels.     

采动区建筑物的保护措施研究

阐述了地下开采引起的不同地表变形形式对建筑物的危害,探讨了采动区建筑物的抗变形设计及其保护措施,对采动区建筑物保护提出了今后工作和研究的建议,进而拓宽了地下开采后地面建筑物保护研究的思路。     

黄土地区小流域坡面侵蚀研究

针对黄土地区小流域坡面侵蚀的特点,分析了土壤、土地类型、坡度等对其的影响,并通过野外大型降雨装置,依据坡面径流理论,模拟分析了不同土地类型下坡面的产流过程,为小流域坡面侵蚀的进一步研究工作提供参考。     

Effects of submerged macrophytes on sediment resuspension and internal phosphorus loading in Lake Hiidenvesi (southern Finland)

The effects of submerged macrophytes on sediment resuspension and internal phosphorus loading in the shallow Kirkkoj?rvi basin of Lake Hiidenvesi were studied by sedimentation traps and sediment and water samples. During the 83 d study period, 793 g DW m(-2) of sediment was resuspended within the stand formed by Ranunculus circinatus, Ceratophyllum demersum and Potamogeton obtusifolius. Outside the stand, 1701g DW m(-2) sediment resuspension was measured during the same period. Water turbidity and concentration of suspended solids (SS) were significantly lower within the plant bed compared with the surrounding water area. Despite the higher concentration of inorganic suspendoids, the concentration of chlorophyll a was higher in the open water than within the submerged plant bed, owing to the enhanced nutrient recycling rate in the absence of submerged plants. With the resuspended sediment, 11.8 mg Pm(-2)d(-1) was brought into the water column within the stand and 24.5 mg Pm(-2)d(-1) outside the stand. Within the macrophyte stand, resuspended particles absorbed phosphorus from the water (indicated by the inverse relationship between SS and soluble reactive phosphorus), which was probably connected to the lowered phosphorus concentration of surface sediment due to uptake by macrophytes.     

阳泉矿区开采对房屋地基的影响

对阳泉矿区煤炭开采所造成的地面沉陷的形成原因和现状进行了分析,就矿区面貌建设过程中廉价廉租房问题,对设计人员提出了一些应注意的事项.     

凤阳县九华山矿区废弃露天采场治理

简要介绍了九华山矿区的地理地质背景,分析了矿山地质环境问题,有针对性地进行了建设用地工程、林业用地工程等矿山地质环境治理工程的布局,最后强调了地质环境治理对恢复矿山生态环境,促进县域经济发展的意义。     

Sources and growth dynamics of fecal indicator bacteria in a coastal wetland system and potential impacts to adjacent waters

Coastal wetlands are receiving increased attention as a putative source of fecal indicator bacteria (FIB) in Southern California coastal waters. We examined temporal trends of water and sediment-associated FIB after rain events along with spatial sediment characteristics at two sites within the Santa Ana River wetlands and made comparisons to FIB levels observed in adjacent surf zone waters. During the first two rain events, total coliforms (TC), Escherichia coli (EC) and enterococci (ENT) in wetland water and sediment samples peaked either on the same day or within several days of the rain event, while the third resulted in elevated wetlands sediment TC levels only. TC in adjacent coastal waters consistently peaked on the same day as the rain event and decreased quickly thereafter (within 1 day). The TC/EC ratios of surf zone samples consistently fell below 10, indicating an increased probability of human fecal contamination whereas wetland TC/EC ratios were higher, averaging approximately 60 and 14 at each site. These results suggest sediment-associated FIB populations may be distinct from those found in the water samples, or at least have internal dynamics independent of water-borne populations. Increases in sediment-associated FIB may be due to in situ population growth and/or increased survival due to changes in environmental parameters (salinity, moisture and nutrient input) resulting from the rain events. Spatial differences in between the two sites may be due to sediment differences such as organic content and finer grain size and/or discrete sources of FIB.     

遂宁市安居区琼江河岸线景观与生态规划设计

针对现代人们热衷于城市河流景观改造设计的浪潮,分析了以往对待河流的方式,通过遂宁市安居区琼江河岸线景观与生态规划设计这个实例,探讨人们该以怎样的方式介入城市河流景观的规划与设计。     

Impacts of mercury contaminated mining waste on soil quality, crops, bivalves, and fish in the Naboc River area, Mindanao, Philippines

Rice paddy fields in the Naboc area, near Monkayo on the island of Mindanao, Philippines, have been irrigated four times a year over the last decade using Naboc River water contaminated with mercury (Hg) by artisanal gold mining in the Diwalwal area. Silt containing up to at least 90 mg Hg/kg (d.w.) has been deposited in rice paddy fields during the 1990s and this has been repeatedly mixed into the rice root zone through ploughing. Hg in the rice paddy field soils averages 24 mg Hg/kg and generally exceeds the UK and Canadian soil quality thresholds for agricultural soils as well as the proposed Dutch Intervention value and the USEPA soil ingestion Soil Screening Level (SSL) for inorganic Hg. Much lower Hg concentrations (0.05-0.99 mg/kg) within the range expected for uncontaminated soils, characterise soils on which corn and bananas are cultivated, largely because these are not irrigated with Hg-contaminated water from the Naboc River. The estimated total weekly MeHg intake for a person living in the Naboc area related to the weekly consumption of 2.1 kg of rice grown on Hg-contaminated soils (15 microg MeHg) in conjunction with 1 kg of fish (220 microg MeHg) and 100 g of mussels (50 microg MeHg) from the Naboc River, would total 285 microg MeHg (equivalent to 4.75 microg/kg bw for a 60 kg adult), which is nearly three times the JECFA PTWI of 1.6 microg/kg bw. This will significantly contribute to the population mercury exposure and might explain why 38% of the local inhabitants were classified as Hg intoxicated during a mercury toxicity assessment [Drasch GS, B?se, O'Reilly S, Beinhoff C, Roider G, Maydl S. The Mt. Diwata study on the Philippines 1999-assessing mercury intoxication of the population by small scale gold mining. Sci Total Environ 2001; 267(1-3): 151-168.].     

Internal loading of phosphorus in a sedimentation pond of a treatment wetland: effect of a phytoplankton crash

Sedimentation ponds are widely believed to act as a primary removal process for phosphorus (P) in nutrient treatment wetlands. High frequency in-situ P, ammonium (NH₄⁺) and dissolved oxygen measurements, alongside occasional water quality measurements, assessed changes in nutrient concentrations and productivity in the sedimentation pond of a treatment wetland between March and June. Diffusive equilibrium in thin films (DET) probes were used to measure in-situ nutrient and chemistry pore-water profiles. Diffusive fluxes across the sediment-water interface were calculated from the pore-water profiles, and dissolved oxygen was used to calculate rates of primary productivity and respiration. The sedimentation pond was a net sink for total P (TP), soluble reactive P (SRP) and NH₄⁺ in March, but became subject to a net internal loading of TP, SRP and NH₄⁺ in May, with SRP concentrations increasing by up to 41 μM (1300 μl^− 1). Reductions in chlorophyll a and dissolved oxygen concentrations also occurred at this time. The sediment changed from a small net sink of SRP in March (average diffusive flux: − 8.2 μmol m^− 2 day^− 1) to a net source of SRP in June (average diffusive flux: + 1324 μmol m^− 2 day^− 1). A diurnal pattern in water column P concentrations, with maxima in the early hours of the morning, and minima in the afternoon, occurred during May. The diurnal pattern and release of SRP from the sediment were attributed to microbial degradation of diatom biomass, causing reduction of the dissolved oxygen concentration and leading to redox-dependent release of P from the sediment. In June, 2.7 mol-P day^− 1 were removed by photosynthesis and 23 mol-P day^− 1 were supplied by respiration in the lake volume. SRP was also released through microbial respiration within the water column, including the decomposition of algal matter. It is imperative that consideration to internal recycling is given when maintaining sedimentation ponds, and before the installation of new ponds designed to treat nutrient waste.