Decomposition of coniferous forest litter along a heavy metal pollution gradient, south-west Finland

The decomposition of Scots pine (Pinus sylvestris) fine root and needle litter was examined along a heavy metal pollution gradient in the vicinity of Harjavalta Metals Smelter complex at Harjavalta, south-west Finland. The study area was found to exhibit a defined gradient of copper and nickel soil contamination along a 8 km long transect starting at 0.5 km from the point emission source with the highest levels found at this site. The background site is located 200 km from the point source. The majority of the heavy metals are confined to the soil organic layer. Litter decomposition and litter quality were compared between litter types after 12, 18, and 30 months incubation at each of four sites. The analyses clearly showed differences in accumulated mass loss, C:N ratio, and nutrient composition that were related to the site of incubation. Needle and fine root litter that was incubated at 0.5 km had a lower accumulated mass loss, 28.1 and 40.9%, respectively, over time when compared to litter incubated at the background site (37.9 and 50.9%, respectively). Concentrations of exchangeable cations in the litter incubated at 0.5 km were considerably less. The heavy metal contamination may provide an explanation for the amount of mass lost and the litter quality through impacts on the soil microbiota.     

The impact of the Almalyk Industrial Complex on soil chemical and biological properties

The effect of heavy metals on soil free-living nematodes, microbial biomass (C mic) and basal respiration (BR) was studied along a 15 km downwind deposition gradient, originating at the Almalyk Industrial Complex. Soil samples from 0-10 and 10-20 cm layers were collected at 5 km intervals. A significant decrease in heavy metal deposition was found going from the source in the downwind direction and with depth. The soil microbial biomass, basal respiration and derived microbial indices for soil samples from the Almalyk industrial area were analysed. The lowest soil microbial biomass and total number of free-living nematodes were found in soil samples near the industrial complex, with a high heavy metal and weak total organic carbon (C org) content. The highest C mic was found in the soil samples collected 15 km from the pollution source. BR displayed similar results. The derived indices, metabolic quotient (qCO2) and microbial ratio (C mic/C org), revealed significant differences with distance, confirming environmental stress in the first and second locations. The present study elucidates the importance of soil nematode and microbial populations as suitable tools for bio-monitoring the effect of heavy metals on soil systems.     

Understorey vegetation along a heavy-metal pollution gradient in SW Finland

Understorey vegetation of Scots pine forests was studied along a 8-km transect running SE from a Cu-Ni smelter at Harjavalta, SW Finland. Long-term accumulation of heavy metals and sulphur in the forest ecosystem has drastically changed plant communities. Vegetation was almost absent up to a distance of 0.5 km from the smelter. The total coverage and the number of plant species increased with increasing distance from the smelter. Ordination by global non-metric multidimensional scaling (GNMDS) indicated that the floristic composition was differentiated in response to the pollution level. The main compositional gradient of GNMDS was correlated with the heavy metal concentrations in the organic soil layer and with the size of the overstorey trees. Vascular plants were more pollution-resistant than ground lichens, whereas mosses were the most sensitive plant group. In addition to heavy metals, nutrient imbalances and the considerably reduced water-holding capacity of the surface soil also restrict plant recolonisation on the degraded sites.     

Nematode communities in contaminated river sediments

Nematode communities of eight sites from three river catchments were investigated in terms of the genera composition, feeding types, and life-history strategists. The sampling sites showed a gradient of anthropogenic contamination with heavy metals and organic pollutants being important factors in differentiating the sites. Nematode community structure was related to sediment pollution and the hydro-morphological structure of the sampling sites. Heavily contaminated sites were characterized by communities with high relative abundances of omnivorous and predacious nematodes (Tobrilus, c-p 3; Mononchus, c-p 4), while sites with low to medium contamination were dominated by bacterivorous nematodes (Monhystera, Daptonema; c-p 2) or suction feeders (Dorylaimus, c-p 4). The relatively high Maturity Index values in the heavily polluted sites were surprising. Nematodes turned out to be a suitable organism group for monitoring sediment quality, with generic composition being the most accurate indicator for assessing differences in nematode community structure.     

Nematode community structure as bioindicator of soil heavy metal pollution along an urban–rural gradient in southern Shenyang, China

Effects of heavy metals caused by urbanisation on soil nematode communities were investigated along an urban–suburban–rural gradient in southern Shenyang, China. The numbers of total nematodes increased significantly along the urban–rural gradient. Similar trends were observed in the values of Structure Index (SI), with lower values found in urban site and higher in the rural site. Generic richness and SI were sensitive indicators for assessing the effect of heavy metals on soil nematode communities. The Canonical Correspondence Analysis (CCA) indicated that copper concentration and Cation Exchange Capacity (CEC) were most important environmental parameters that influenced nematode distribution.     

Cadmium in soil solutions from a transect of soils away from a fertiliser bin

The effects of high inputs of phosphate fertiliser on Cd concentrations were studied in soil solutions extracted from topsoils. Soils were sampled along a transect at distances of 1-100 m away from a fertiliser bin. The transect was sampled four times during 1 year. Soil solutions were analysed for Cd, pH, major cations and anions, and other heavy metals (As, Cr, Cu, Pb). For one of the transect samplings, soil total Cd, Cr, Cu, Pb and P were also measured. Cd speciation in the soil solutions was calculated by the GEO-CHEM-PC computer program. Chemical composition varied substantially along the transect, and also between samplings, indicative of seasonal effects and the influence of a fresh application of superphosphate fertiliser during the year. Application of fertiliser decreased soil solution pH and increased the levels of heavy metals in soil solution. Generally, soil total Cd, Cr, Cu, Pb, and P decreased with increasing distance from the fertiliser bin. Correlations between P and the four heavy metals were: P and Cd (R2 = 0.978), P and Cr (R2 = 0.712), P and Pb (R2 = 0.538), P and Cu (R2 = 0.267). Less than 1% of the total Cd in the soil samples was found in the soil solution. The free metal ion Cd2+ accounted for 55-90% of solution Cd. Of the complexed species of Cd, the chloride and sulphate complexes were usually the most important, even when nitrate and phosphate concentrations were relatively high. The presence of As, Cr, Cu and Pb had no effect on Cd speciation.     

Assessment of nematode community structure as a bioindicator in river monitoring

Nematode communities from river water and sediments were assessed for the abundance, feeding types, maturity indices and nematode channel ratio (NCR). The sampling sites studied included different levels of pollution and contamination from agricultural, industrial and sewage sources. The nematode abundance found in the sediment samples was more than that in the water samples. The lowest nematode abundance in sediment samples and the lowest NCR in water samples were both found at the industrial pollution site. Water samples showed positive correlation between the NCR and river pollution index (RPI). Mean maturity indices in sediment samples were inversely correlated with RPI. The pollutant source determined the relationship between NCR and pollution level, while maturity index always showed negative correlation with pollutant level regardless of the pollutant sources. The nematode abundance and its community structure were both reliable bioindicators for monitoring long-term river pollution in both qualitative and quantitative aspects.     

Aspects of the ecology of Carabidae (Coleoptera) from woodlands polluted by heavy metals

The carabid faunas of six woodlands at varying distances from a source of heavy metal pollution were studied. Concentrations of zinc, lead, cadmium and copper were determined in three surface layers at each wood. Whereas no gross effects of pollution on populations were identified, some differences relating to the ecology and life histories of the animals were found. The numbers of individuals and numbers of species of Carabidae at each site were not significantly correlated to metal concentration. However, species diversities (Shannon Weiner H') were. Later dates of median capture of total Carabidae were found in the sites nearest to the pollution source. This also occurred with a common species, Nebria brevicollis. At the most polluted site this species also showed an absence of summer diapause. This may be relatd to scarcity of prey. Negative correlations of numbers of spring breeders with metal concentration but positive correlations of numbers of spring breeders with in all the soil layers. The sites were significantly different in the relative distributions of individuals in each of four size categories.     

Effects of heavy metal exposure on the condition and health of adult great tits (Parus major)

We examined the possible effects of heavy metal exposure on the quality and health of adult great tits (Parus major) at four study sites along a pollution gradient near a non-ferrous smelter in Belgium. Tarsus length, wing length, body mass and condition of great tits were compared with respect to study site, age (first-year and older great tits), sex and season (birds caught in winter and during breeding). Tarsus length did not differ significantly among study sites. The wing length of great tits was larger at the study site furthest from the smelter, especially for older great tits. The length of the outermost tail feathers, however, did not differ significantly among study sites. We found no signs of loss of body mass or condition towards the pollution source. The body mass and condition was lowest for female great tits at the site furthest from the smelter, especially during winter. Haematocrit values did not differ significantly among sites. Overall, we found no clear significant effects of heavy metal pollution on morphological measurements and health parameters of great tits.     

Limited effects of heavy metal pollution on foraging and breeding success in the curlew (Numenius arquata)

We examined the effect of heavy metal pollution on the foraging success and breeding performance of the curlew (Numenius arquata) along a documented pollution gradient from a point source, and also by comparing foraging and breeding parameters between the polluted site and two non-polluted areas. Prey biomass and abundance, and foraging success did not vary along the pollution gradient, and were no less at the polluted site than in the non-polluted areas. Furthermore, there was no difference in adult weight during incubation between the polluted and non-polluted areas. There were also no differences in measures of breeding success along the pollution gradient, or between areas, which could be attributed to pollution per se. Egg shells from the polluted area had higher concentrations of heavy metals than in the non-polluted areas, and egg shells close to the pollution source were contaminated more than those further from it. However, there was no difference in calcium concentrations of egg shells or egg-shell thickness between areas. We conclude that in this study there were minimal immediate effects of heavy metal pollution on foraging and breeding success in the curlew.     

The impact of heavy metal pollution gradients in sediments on benthic macrofauna at population and community levels

The effect of sediment pollution on benthos was investigated in the vicinity of a large sewage treatment outflow at Incheon North Harbor, Korea. Animal size, vertical distribution and standard community parameters were analyzed along a 3 km transect line (n = 7). Univariate parameters showed a general trend of increasing species diversity with increasing distance from the pollution source. Multi-dimensional scaling analysis led to the clear separation of 3 locational groups, supporting gradient-dependent faunal composition. The innermost location was dominated by small sub-surface dwellers while the outer locations by large mid to deep burrowers. Looking for the size-frequency distribution, most abundance species (Heteromastus filiformis) showed the presence of larger size animals with increasing proximity to the pollution source. Meanwhile, species-specific vertical distributions, regardless of the pollution gradient, indicated that such shifts were due to species replacement resulting from a higher tolerance to pollutants over some species.     

Relations between Scots pine needle element concentrations and decreased needle longevity along pollution gradients

Scots pine (Pinus sylvestris L.) shoots were sampled along transects near one urban pollution source and two smelters. Needle Mg, P and K concentrations decreased from the second to the fourth age class linearly with needle survival along the urban pollution gradient. Still, over 80% of the average concentration of these nutrients remained in the fourth needle age class. Decreased needle longevity was closely related to the increased heavy metal concentrations near the smelters. Near the urban pollution source, it was related to the increased annual needle mass and the increased needle nutrient concentrations. Decreased Mn accumulation along with needle age was detected near all pollution sources. Leaching of Mn from needles and especially from soil as a cause of decreased needle concentrations is discussed.     

Effects of heavy metal exposure on the condition and health of nestlings of the great tit (Parus major), a small songbird species

In this study we examined the possible effects of heavy metal exposure on the condition and health of great tit nestlings (Parus major) at four study sites along a pollution gradient near a large non-ferrous smelter in Belgium during three consecutive breeding seasons. Our results showed that nestlings were indeed exposed to large amounts of heavy metals. Excrements contained significantly higher concentrations of several heavy metals (silver, arsenic, cadmium, mercury, lead) near the pollution source than at study sites farther away. When taking into account the number of young in the nest at the time of sampling, nestling body mass and condition were significantly reduced at the most polluted site. Nestlings at the two most polluted sites fledged significantly later than at the least polluted site. We also observed growth abnormalities of the legs near the pollution source. Tarsus length, wing length and haematocrit values did not differ significantly among study sites.     

Microbial indicators of heavy metal contamination in urban and rural soils

Urban soils and especially their microbiology have been a neglected area of study. In this paper, we report on microbial properties of urban soils compared to rural soils of similar lithogenic origin in the vicinity of Aberdeen city. Significant differences in basal respiration rates, microbial biomass and ecophysiological parameters were found in urban soils compared to rural soils. Analysis of community level physiological profiles (CLPP) of micro-organisms showed they consumed C sources faster in urban soils to maintain the same level activity as those in rural soils. Cu, Pb, Zn and Ni were the principal elements that had accumulated in urban soils compared with their rural counterparts with Pb being the most significant metal to distinguish urban soils from rural soils. Sequential extraction showed the final residue after extraction was normally the highest proportion except for Pb, for which the hydroxylamine-hydrochloride extractable Pb was the largest part. Acetic acid extractable fraction of Cd, Cu, Ni, Pb and Zn were higher in urban soils and aqua regia extractable fraction were lower suggesting an elevated availability of heavy metals in urban soils. Correlation analyses between different microbial indicators (basal respiration, biomass-C, and sole C source tests) and heavy metal fractions indicated that basal respiration was negatively correlated with soil Cd, Cu, Ni and Zn inputs while soil microbial biomass was only significantly correlated with Pb. However, both exchangeable and iron- and manganese-bound Ni fractions were mostly responsible for shift of the soil microbial community level physiological profiles (sole C source tests). These data suggest soil microbial indicators can be useful indicators of pollutant heavy metal stress on the health of urban soils.     

公路周边土壤重金属污染及植物修复

随着中国公路建设迅猛发展,公路周边土壤重金属污染也日趋严重。文中结合近年来国内外的研究情况,以公路土壤污染中的铅、镉、锌、铜、铬等元素为重点,对土壤重金属污染的危害、分布特征及其影响因素,以及相应的植物修复技术等相关研究进行综述。     

Oribatid mite communities and metal bioaccumulation in oribatid species (Acari, Oribatida) along the heavy metal gradient in forest ecosystems

The responses of oribatid communities to heavy metal contamination were studied. Concentration of cadmium, copper and zinc in nine oribatid species along a gradient of heavy metal pollution was measured. Oribatid mites were sampled seasonally during two years in five forests located at different distances from the zinc smelter in the Olkusz District, southern Poland. The most numerous and diverse oribatid communities were found in the forest with moderate concentrations of heavy metals. Analysis by atomic absorption spectrophotometry revealed large differences in metal body burdens among species. All studied oribatid species appeared to be accumulators of copper with Oppiella nova, Nothrus silvestris and Adoristes ovatus characterized by the highest bioaccumulation factors. Most species poorly accumulate cadmium and zinc. The accumulation of heavy metals in the body of oribatids was not strictly determined by their body size or the trophic level at which they operate.     

雷州半岛土壤重金属分布特征及其污染评价

在雷州半岛采集了106个土壤表层样品,分析了其中8种重金属元素(Cu、Pb、Zn、Cr、Ni、Cd、Hg和As)的全量.结果表明,雷州半岛土壤重金属污染由高到低排序为Ni＞Cr＞Hg＞Cu＞Zn＞Cd＞As＞Pb,Zn、Cd、As和Pb质量浓度均没有超标,Hg和Cu质量浓度超标率亦不高,但Ni和Cr平均质量浓度达49.81、87.13 mg/kg,高于国内外其他对照区域,超标率分别为25.47%和24.53%;重金属元素在雷州半岛各土壤利用类型中分布规律不明显,按4种主要土壤利用类型受重金属污染程度大小排序为甘蔗地＞果园土＞水田＞菜地;雷州半岛土壤综合污染指数总平均为0.970,土壤总体上尚清洁,重金属污染处于警戒水平;雷州半岛各区域中,徐闻、雷州两地土壤重金属质量浓度明显高于其他地区,其主要原因是徐闻、雷州两地成土母质主要为玄武岩,造成土壤Cr、Ni及其他重金属背景值较高.     

Heavy metal contamination characteristic of soil in WEEE (waste electrical and electronic equipment) dismantling community: a case study of Bangkok,Thailand

Sue Yai Utit is an old community located in Bangkok, Thailand which dismantles waste electrical and electronic equipment (WEEE). The surface soil samples at the dismantling site were contaminated with copper (Cu), lead (Pb), zinc (Zn), and nickel (Ni) higher than Dutch Standards, especially around the WEEE dumps. Residual fractions of Cu, Pb, Zn, and Ni in coarse soil particles were greater than in finer soil. However, those metals bonded to Fe-Mn oxides were considerably greater in fine soil particles. The distribution of Zn in the mobile fraction and a higher concentration in finer soil particles indicated its readily leachable character. The concentration of Cu, Pb, and Ni in both fine and coarse soil particles was mostly not significantly different. The fractionation of heavy metals at this dismantling site was comparable to the background. The contamination characteristics differed from pollution by other sources, which generally demonstrated the magnification of the non-residual fraction. A distribution pathway was proposed whereby contamination began by the deposition of WEEE scrap directly onto the soil surface as a source of heavy metal. This then accumulated, corroded, and was released via natural processes, becoming redistributed among the soil material. Therefore, the concentrations of both the residual and non-residual fractions of heavy metals in WEEE-contaminated soil increased.     

某矿区土壤和地下水重金属污染调查与评价

为了解湘南某矿区土壤和地下水重金属污染状况,对该矿区东河流域附近重金属污染源进行了调查,同时,对地下水和土壤样品进行了采样分析,结果表明：（1）该矿区东河流域附近的主要污染源有18个,其中有色金属选厂、尾矿库、采矿场和冶炼厂是排放重金属较多的污染源;（2）20个采样点中土壤重金属Pb、Cd、Zn、As和Hg大部分超过国家土壤环境质量标准（GB15618-1995）,综合污染指数P综〉1,该矿区主要的重金属污染元素为Cd、As和Hg,且土壤中Cd、Zn和As的含量两两之间存在着极显著的正线性相关关系;（3）重金属元素在土壤中的纵向迁移不明显,该矿区附近20个采样点的地下水并未受到污染,综合污染指数P综〈1。20个采样点地下水Pb、Cd、Zn、As、Hg浓度均能达到地下水质量标准（GB／T14848．9）中的Ⅲ类标准。     

Potentially toxic metals in ombrotrophic peat along a 400 km English-Scottish transect

Four samples of ombrotrophic peat were collected from each of 10 upland locations in a transect from the southern Pennines to the Highland Boundary Fault, a total distance of ca. 400 km. Bulk compositions and other properties were determined. Total contents of Al and heavy metals (Ni, Cu, Zn, Cd, Pb) were determined following digestion with hydrofluoric acid, and concentrations of metals extractable with dilute nitric acid were also measured. Supernatants obtained from aqueous extractions of the peat samples were analysed for pH, major cations and anions, dissolved organic carbon and dissolved metals, and concentrations of free metal ions (Al(3+), Ni(2+), etc.) were estimated by applying a chemical speciation model. Both total and HNO(3)-extractable metal concentrations varied along the transect, the highest values being found at locations close to industrial and former mining areas. The HNO(3)-extractable soil metal contents of Ni, Cu and Cd were appreciably lower than lowest-observed-effect-concentrations (LOEC) for toxicity towards microorganisms in acid, organic rich soils. However, the contents of Zn at two locations, and of Pb at five locations exceeded LOECs, suggesting that they may be exerting toxic effects in the peats. Soil solution concentrations of free heavy metal ions (Cu(2+), Zn(2+), Cd(2+), Pb(2+)) were substantially lower than LOECs for toxicity towards vascular plants, whereas concentrations of Al(3+) were near to toxic levels at two locations.