Ecophysiological responses of Empetrum nigrum to heavy metal pollution

Chlorophyll, organic (citric and malic acids) and abscisic acid (ABA) contents and stem water potential were measured to indicate possible physiological effects of heavy metal deposition on Empetrum nigrum L. (crowberry). The leaves and stems of E. nigrum were collected at distances of 0.5 and 8 km from the Cu-Ni smelter at Harjavalta, south-west Finland. All the investigated parameters were clearly affected by heavy metal emissions. Chlorophyll contents in the leaves and organic acid contents in the leaves and stems were lower close to the emission source. Generally found increase in organic acid contents with increasing Ni concentrations was not found, which might be due to the lower production of organic acids measured by decreased photosynthesis near the smelter. In contrast, ABA contents in stems and leaves in general, were higher in plants growing 0.5 km from the pollution source. Close to the smelter the stem water potential of E. nigrum was less negative during the day but more negative during the night. These results suggest that smelter emissions have a negative effect on the ecophysiology of E. nigrum even though it is considered to be a tolerant species to heavy metals.     

微生物矿化修复重金属污染土壤

以选矿厂附近土壤为研究对象,分析了土壤中交换态重金属含量,As、Pb、Cd、Zn和Cu的交换态浓度为14.01、4.95、0.64、33.46和12.95 mg/kg。基于生物矿化原理,利用碳酸盐矿化菌生长代谢过程产生的脲酶来分解底物尿素,产生碳酸根离子,固结重金属离子,使得土壤中活泼的重金属离子转变为碳酸盐矿物态,降低其危险。研究了温度、pH和重金属离子对酶活性的影响,发现环境30℃温度有利于促进酶活性;在弱酸性条件下,底物分解量减少15%;重金属离子在低浓度时对脲酶活性影响不大,浓度提高后对酶活性抑制作用没有加剧。将制备好的微生物矿化修复制剂喷洒于1 000 m2的污染土壤中,实验结果发现,土壤中交换态重金属离子含量在0～20 cm范围内明显减少,As、Pb、Cd、Zn和Cu的交换态浓度分别减少至2.37、1.25、0.31、16.67和3.42 mg/kg。     

Distribution of heavy metal contents of urban soils in parks of Seville

Several metals in urban soils of Seville were extracted by two methods, which respectively give estimates of the available and ‘quasi total’ contents. Although the soils did not show strong heterogeneity in their general properties, high dispersion of the contents in those metals with greater relative availability, Cu, Pb and Zn, as compared to others suggested that pollution with these three metals could occur in some sampling sites. It was shown that the contents in these metals tend to increase as the historic quarters of the city are approached. Using reference values given by the Québec Ministry of Environment it was shown that those green areas closer to the historic centre present contents in Pb, Zn and particularly Cu that often exceed the acceptable limits for residential, recreational and institutional sites. From background contents for Seville soils estimated from a park located on the outskirts, a pollution load index (PLI) for each sampling site was calculated for the set of these three metals. It was shown that the PLI tends to increase as traffic density increases and as distance from main traffic decreases, but poor regressions were obtained, suggesting that other variables different from traffic should be considered.     

城市生活垃圾焚烧处理过程中重金属迁移规律研究

通过采集厦门2个垃圾焚烧发电厂进厂垃圾、渗滤液、飞灰、炉渣和烟气样品，分析垃圾组成成分及各组分的重金属含量，结果表明，垃圾中以厨余、橡塑类和纸类为主，共占到垃圾干基的78．08％，重金属含量大小次序为Zn〉Cu〉Pb〉Cr〉Ni〉Cd〉Hg；垃圾渗滤液中除Zn外，其他金属的含量都较低，一厂渗滤液中重金属Ni、Zn迁移量较大，分别达到24．46％和8．52％。二厂渗滤液中重金属的迁移有相同的趋势，但含量相对较高。垃圾焚烧后其重金属主要分布在飞灰和废渣中，烟气中的含量非常少，不同金属的含量均有差别，这与金属的性质有很大关系；通过浸出毒性分析，飞灰中重金属酸溶态含量多，容易浸出，属于危险废物。同时，不同烟气处理工艺产生的飞灰的重金属浸出量有很大差别。     

Evaluation of heavy metal concentrations of edible wild-grown mushrooms from China

ABSTRACT

The heavy metal contents (Co, Cu, Fe, Mn, Ni, and Zn) of eight species of wild edible mushrooms from China were determined. The analyses were performed using inductively coupled plasma atomic emission spectrophotometry after microwave digestion. The contents of Co, Cu, Fe, Mn, Ni, and Zn in caps of mushroom samples were 0.7–7.2, 16.2–70.4, 371–1315, 12.5–29.8, 7.1–58.5, and 77.8–187.4 mg kg^?1 dry matter (dm), respectively, while considerable differences were found to be 1.8–25.9, 9.8–36.3, 288–6762, 13.3–103.9, 5.9–78.7, and 38.7–118 mg kg^?1 dm for stipes. The results indicated that higher levels of Co, Fe, and Ni were found in the mushrooms samples analyzed. Zinc and manganese levels were similar to previous reports, whereas Cu was lower than literature values. Correlation analysis suggested that significant correlations were found between the minerals determined and the greatest amount of contamination is associated with Co, Mn, Ni, and Fe. The results of this study indicate that heavy metal contents in mushroom species are mainly related to the mineral resources of sampling sites.     

Effect of soil on microbial responses to metal contamination

An experiment was conducted to investigate microbial responses to metal inputs in five soils with varying clay and organic contents; one soil had also a higher pH. These soils were treated with a low metal, sewage sludge control or with this sludge contaminated to achieve Cu=112, Ni=58 and Zn=220 mg kg(-1) in medium and Cu=182, Ni=98 and Zn=325 mg kg(-1) in high metal soils. CO(2) evolution rates were measured at 1 week and at 4-5-day intervals thereafter until the end of the incubation (7 weeks). Extractable metals (CaCl(2) and water), biomass C, metabolic quotient, ergosterol, bacterial-fungal phospholipid fatty acid (PLFA-3 weeks only) ratio and mineral N were measured at 3 and 7 weeks. Metal inputs caused a marked increase in metal availability in the slightly acidic sandy loams, a smaller increase in slightly acidic clays and had little effect in the alkaline loam. After an initial increase in CO(2) evolution with metal inputs in all soils, the high metal treatment alone caused a significant decrease at later stages, mainly in sandy loams. Although biomass C and metabolic quotient decreased in all soils with higher metal inputs, the effect was more pronounced in the sandy loams. Metal inputs increased ergosterol and decreased bacterial-fungal PLFA ratios in most soils. Larger mineral N contents were found in all high metal soils at 3 weeks but, after 7 weeks, metals caused a significant decrease in sandy loams. CaCl(2) and water-extractable Cu, Ni and Zn contents were closely correlated with microbial indices in sandy loam but not in clay soils. Overall, the effect of treatments on microbial and extractable metal indices was greater in loams. Within a single series, higher organic soils showed less pronounced responses to metal inputs, although this trend was not always consistent.     

天津市典型河网区沉积物中重金属分布及生态风险评价

选择天津市典型河网区为研究对象,分析了沉积物中6种重金属(Cr、Cu、Mn、Ni、Pb和Zn)的分布特征,并采用富集系数法和潜在生态危害指数法分析了重金属的来源,进而评价了其生态风险。结果表明,表层沉积物中Cr、Cu、Mn、Ni、Pb和Zn的平均含量分别是58.18、23.52、524.60、22.93、25.24和49.51 mg/kg,其中Cr、Mn和Ni含量均低于天津市土壤背景值,而Cu、Pb和Zn含量在部分样点高于背景值;在垂直分布上,沉积物中Cr和Ni的含量相对稳定,而Cu、Mn、Pb和Zn的含量从底层到表层均先增加后降低。重金属富集系数(EF)分析显示,河网区表层沉积物中Cu和Zn在个别样点以及Pb在近一半样点存在人为输入过程(EF1.5),与接纳上游及区域的生活污水、农田退水有关,而Cr、Mn和Ni均来自自然源。重金属综合潜在生态危害指数(RI)评价表明,整个河网区表层沉积物为轻微生态危害水平,对区域的水环境质量不构成威胁。     

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。     

Evolution of heavy metal speciation during the aerobic composting process of sewage sludge

The contents of heavy metals and their bioavailability to the soil-plant system were the major limitation to the application of sewage sludge compost in soil. This study was conducted to determine the evolution of heavy metal speciation in the course of an aerobic composting, and investigate the influence of changes of composting process parameters including pH, temperature and organic matter (OM) content on distribution of heavy metal speciation in composted sludge. The sequential extraction procedure developed by Tessier et al. was used in sludge compost to determine the heavy metal speciation. Results showed that, during composting, (1) the contents of the residue fraction for Pb, Zn and Cd were decreased but those for Ni and Cr were increased; the Cu residue fraction was almost constant; (2) the contents of the total mobile fractions (including fractions 1-4) for Zn and Pb were significantly increased, but the increase of those for Cu and Ni were not so remarkable; (3) there were significant degrees of correlation between heavy metal fractions and changes of some selected parameters (for example, pH, composting temperature, and OM content). Only the content of the total mobile fractions for Cu could be predictable from its total content. For the prediction of the total mobile fractions of Zn, Ni, Cd and Cr, the R(2) value was significantly increased by the inclusion of other variables such as pH, temperature and OM content.     

Comparison of heavy metal bioaccumulation in freshwater molluscs of urban river habitats in Vienna

Two bivalve species (Anodonta sp. and Unio pictorum) and two gastropod species (Radix ovata and Viviparus sp.) were tested as bioindicators in moderately metal-polluted Danube River habitats of Vienna. Molluscs, two sediment fractions and water samples were collected between April 1993 and May 1994 at six sampling sites located at five waters in Vienna. The unionid clams were dissected into viscera, gill, mantle, adductor muscle and shell, gastropods into soft body and shell. Analyses of Cd, Pb, Cu and Zn were carried out with atomic absorption spectrophotometry. Bioaccumulation of metals varied strongly according to sampling site, metal and mollusc species. Cd, Cu and Zn loads of the molluscs exceeded environmental concentrations, but not so for the apparently less bioavailable Pb. Sampling site had a significant influence on metal bioconcentrations, e.g. the Neue Donau sampling sites, where traffic emissions probably caused increased metal contents. High environmental metal concentrations in Danube harbours were poorly reflected by the bioindicator species. The gastropods showed about 20-fold higher concentrations than the bivalves. This may indicate a higher Cu regulation capacity of bivalves. The suitability of the investigated mollusc species as bioindicators depends on their specific relationship to the environmental compartment. Anodonta sp. and R. ovata concentrations were more likely related to the contents of the fine sediment fraction, which may be explained by their close association to the sediments. The metal concentrations of the deposit- and filter-feeder Viviparus sp. correlated more closely with suspended matter and filtrate contents.     

Impact of a smelter closedown on metal contents of wheat cultivated in the neighbourhood

BACKGROUND: The contamination of soils by heavy metals engenders important environmental and sanitary problems in Northern France where a smelter has been located for more than one hundred of years. It has been one of the most important Pb production sites in Europe until its closedown in March 2003. Ore smelting process generated considerable atmospheric emissions of dust. Despite an active environmental strategy, these emissions were still significant in 2002 with up to 17 tonnes of Pb, 32 tonnes of Zn and 1 tonne of Cd. Over the years, the generated deposits have led to an important contamination of the surrounding soils. Previous studies have shown pollutant transfers to plants, which can induce a risk for human and animal health. The objective of this study was to evaluate the consequences of the smelter closedown on the Cd and Pb contents of wheat (grain and straw) cultivated in the area. METHODS: Paired topsoil and vegetable samples were taken at harvest time at various distances to the smelter. The sample sites were chosen in order to represent a large range of soil metal contamination. Sampling was realised on several wheat harvests between 1997 and 2003. 25 samples were collected before the smelter closedown and 15 after. All ears of about 1 m long of two rows were manually picked and threshed in the lab. Similarly, straw was harvested at the same time. Total metal contents in soil and wheat samples were quantified. RESULTS: A negative correlation between metal concentrations in soil and the distance to the smelter was shown. The wheat grain and straw showed significant Cd and Pb contents. The straw had higher metal contents than the grain. During the smelter activity, the grain contents were up to 0.8 mg kg(-1) DM of Cd and 8 mg kg(-1) DM of Pb. For the straw, maximum contents were 5 mg kg(-1) DM of Cd and 114 mg kg(-1) DM of Pb. After the smelter closedown, we observed a very large decrease of Pb in the grain (82%) and in the straw (91%). A smaller decrease was observed for Cd in grain. Despite this improvement, 80% of the studied samples remained non-acceptable for human consumption, according to the European legislation values, due to a high Cd content. DISCUSSION: Results highlighted a difference in metal accumulation in the plant organs as well as a difference in metal uptake. The approach pointed out the importance of atmospheric fallout in the wheat contamination pathways for Pb. The smelter closedown has lead to a decrease of the Pb content in wheat. It is interesting to relate this finding with the lead blood levels in children living close to the smelter. CONCLUSIONS: Those results have confirmed the importance of dust fallout in the plant contamination pathways. Before the closedown, Pb measured in the plant was principally originating from the smelter dust emissions. It raised the question of the sanitary risks for humans and animals living in the surrounding a of the smelter. RECOMMENDATIONS AND PERSPECTIVES: In the literature, very few articles take the dust deposit as contamination pathways for crops into consideration. However, in highly contaminated sites, this pathway can be very important. Thus, it would be worthy studying the uptake of metal contaminants by plants through the foliar system.     

Study of metal concentrations in the environment near diesel transport routes

In recent years, a river-dredging project has been executed in Nantou, Taiwan. A large number of diesel vehicles carrying gravel and sand shuttle back and forth on the main traffic roads (Tai-16 and Tai-21). The purpose of this study is to figure out the levels of metals contributed by those vehicles to the surrounding environment. Eight stations along the roadside of diesel transport routes were selected as exposure sites, while a small village located about 9 km away from the diesel transport routes was selected as the control site. The mass concentrations of coarse and fine particulate matter indicated that contributions from traffic fleets resulted in a higher percentage of coarse particulate matter in the ambient air at exposure sites in comparison with that at control site. Significantly higher values of EC (elemental carbon) concentrations and ratios of EC/OC (organic carbon) at exposure sites indicate that diesel vehicles at exposure sites contributed a greater amount of pollutants than gasoline vehicles. Exposure site concentrations for all metals measured (Fe, Al, Mn, Pb, Zn, Cu, Ni, Mo and As) for fine and coarse particulate matter were all higher than those at the control site. Recorded levels of metal contents in road dust and riverside soil near Tai-16 and Tai-21 showed that while the traffic fleet did not increase the metal contents of crustal elements in the road dust, it did significantly increase the metal contents of traffic-related elements. Enrichment factors (EFs) were calculated with respect to road dust (EF_road) and with respect to the samples of riverside soil (EF_river). Among these metals, Mo was the most highly-enriched metal. The extremely high EF_river value (4300) of Mo indicates that these stations were highly polluted by diesel emission. Whereas the significantly high EF_road value (810) of Mo implies that a considerable of Mo was emitted from tailpipe of diesel vehicles.     

Heavy metal control in microalgae cultivation with power plant flue gas entering into raceway pond

Environmental Science and Pollution Research - The heavy metal sources of large-scale raceway pond microalgae cultivation with flue gas were investigated to reduce heavy metal contents in...     

Strategies of heavy metal uptake by three plant species growing near a metal smelter

Some higher plant species have developed heavy metal tolerance strategies which enable them to survive and reproduce in highly metal-contaminated soils. We have investigated such heavy metal uptake and accumulation strategies of two absolute metallophyte species (Armeria maritima ssp. halleri and Cardaminopsis halleri) and one pseudometallophyte (Agrostis tenuis) growing near a former metal smelter. Samples of plant parts and soil were analysed for Zn, Cd, Pb, and Cu. In soil, there were two dominant types of metal concentration gradients with depth. Under the absolute metallophytes, extremely high metal contents were measured in the surficial Ah horizon, followed by a strong decrease in the underlying soil horizons (L(11) and L(12)). Under the pseudometallophyte, metal concentrations in the Ah horizon were much lower and fewer differences were observed in metal concentrations among the Ah, L(11), and L(12) horizons. The concentrations of Zn, Cd, Pb, and Cu in Agrostis tenuis roots were greater than concentrations in leaves, indicating significant metal immobilisation by the roots. For C. halleri, Zn and Cd concentrations in leaves were >20,000 and >100 mg kg(-1), respectively, indicating hyperaccumulation of these elements. Armeria maritima ssp. halleri exhibited root concentrations of Pb and Cu that were 20 and 88 times greater, respectively, than those in green leaves, suggesting an exclusion strategy by metal immobilisation in roots. However, Zn, Cd, Pb, and Cu concentrations in brown leaves of Armeria maritima ssp. halleri were 3-8 times greater than in green leaves, suggesting a second strategy, i.e. detoxification mechanism by leaf fall.     

Seasonal changes of metal accumulation and distribution in shining pondweed (Potamogeton lucens)

In this study, submerged aquatic plant Potamogeton lucens, corresponding sediment and water samples were seasonally collected from Lake Sapanca (Turkey) and analysed for their heavy metal contents (Pb, Cr, Cu, Mn, Ni, Zn and Cd). While heavy metals concentrations in the water samples were decreased as Zn > Cr > Ni > Pb > Mn > Cu > Cd, in sediment samples were Mn > Zn > Ni > Cu > Cr > Pb > Cd, respectively. Generally, heavy metals concentrations in the plant tissues were decreased in sequence of Mn > Zn > Cu > Ni > Cr > Pb > Cd. It was determined that Cu, Mn and Zn were actively transported to the root, where they were accumulated especially in autumn. Lower accumulation factor ratios were seen in spring than other seasons. Cd exhibited a relatively clear pattern of increasing accumulation in P. lucens with increasing sediment metal concentrations. Significant positive correlations were observed between Cr, Cu, Ni and Cd contents in sediment and Cd contents in root of P. lucens. The investigations suggested that Ni and Mn have a tendency to be accumulated in leaf especially in autumn and Cr and Cd to be accumulated in shoot especially in summer.     

Decomposition of heavy metal contaminated nettles (Urtica dioica L.) in soils subjected to heavy metal pollution by river sediments

Two incubation experiments were conducted to evaluate differences in the microbial use of non-contaminated and heavy metal contaminated nettle (Urtica dioica L.) shoot residues in three soils subjected to heavy metal pollution (Zn, Pb, Cu, and Cd) by river sediments. The microbial use of shoot residues was monitored by changes in microbial biomass C, biomass N, biomass P, ergosterol, N mineralisation, CO(2) production and O(2) consumption rates. Microbial biomass C, N, and P were estimated by fumigation extraction. In the non-amended soils, the mean microbial biomass C to soil organic C ratio decreased from 2.3% in the low metal soil to 1.1% in the high metal soils. In the 42-d incubation experiment, the addition of 2% nettle residues resulted in markedly increased contents of microbial biomass P (+240%), biomass C (+270%), biomass N (+310%), and ergosterol (+360%). The relative increase in the four microbial properties was similar for the three soils and did not show any clear heavy metal effect. The contents of microbial biomass C, N and P and ergosterol contents declined approximately by 30% during the incubation as in the non-amended soils. The ratios microbial biomass C to N, microbial biomass C to P, and ergosterol to microbial biomass C remained constant at 5.2, 26, and 0.5%, respectively. In the 6-d incubation experiment, the respiratory quotient CO(2)/O(2) increased from 0.74 in the low metal soil to 1.58 in the high metal soil in the non-amended soils. In the treatments amended with 4% nettle residues, the respiratory quotient was constant at 1.13, without any effects of the three soils or the two nettle treatments. Contaminated nettle residues led generally to significantly lower N mineralisation, CO(2) production and O(2) consumption rates than non-contaminated nettle residues. However, the absolute differences were small.     

Patterns of metal soil contamination and changes in terrestrial cryptogamic communities

Correlations between terricolous bryophyte- and lichen- vegetation and edaphic parameters (pH, organic matter, nitrogen, Carbon/nitrogen ratio, Cation Exchange Capacity, and Cd, Pb and Zn soil contents) of soils submitted to a gradient of metal contamination in northern France were performed using statistical analysis. Six classes can be distinguished according to the low-, intermediate- and high-trace metal levels respectively, leading to the conclusion that bryophyte- and lichen-groupings have a strong bioindicative value of the heavy metal pollution of soils.     

Evaluation of heavy metal availability in polluted soils by two sequential extraction procedures using factor analysis

Superficial soil and grass samples from 13 locations affected by several anthropogenic sources (mining, metal factory, traffic emissions) were collected in Gipuzkoa, northern Spain. The more labile metal fractions, the mobile (extracted by 0.01 mol l(-1) CaCl(2)) and the mobilisable (extracted by 0.005 mol l(-1) DTPA), were evaluated using a short sequential procedure with two steps. From the results a short-medium term potential lability of Cd, Cu, Zn and Pb can be concluded. The labile levels were compared with the results obtained using the Tessier sequential procedure. Factor analysis was used to check the associations between the total metal contents in soil and grass, as well as between the levels of the different sequential fractions and the total content in grass. Cd, Cu and Zn labile levels were related to total metal grass contents indicating its suitability for the availability studies in polluted soil-plant system.     

Heavy metal sequential extraction methods--a modification for tropical soils

Sequential extractions of metals can be useful to study metal distributions in various soil fractions. Although several sequential extraction procedures have been suggested in the literature, most were developed for temperate soils and may not be suitable for tropical soils with high contents of Mn and Fe oxides. The objective of this study was to develop a sequential fractionation procedure for Cu and Zn in tropical soils. Extractions were performed on surface (0–20 cm) samples of ten representative soils of Sao Paulo State, Brazil. Chemically reactive Mn forms were satisfactorily assessed by the new modified procedure. Amorphous and crystalline Fe oxides were more selectively extracted in a new two-step extraction. Soil-born Zn and Cu were primarily associated with recalcitrant soil fractions. The proposed procedure provided more detailed information on metal distribution in tropical soils and better characterization of the various components of the soil matrix. The new procedure is expected to be an important tool for predicting the potential effects of environmental changes and land application of metals on the redistribution of chemical forms of metals in tropical soils.     

Response of the lichen Cladonia rei Schaer. to strong heavy metal contamination of the substrate

The phenomenon of mass occurrence of the lichen Cladonia rei in extremely contaminated post-smelting slag dumps was studied in relation to metal accumulation capacity of this lichen. The research was aimed to evaluate the relationships between element contents in the thalli and in the corresponding substrate. The study was conducted in terms of a wide spectrum of Zn, Cd, Pb and As contents. The concentrations of these elements in the lichen thalli and substrate samples were measured. Various regression models were considered to find the best fitted one that greatly reflects the dependencies. Various Cladonia species and the hyperaccumulator Diploschistes muscorum were also included in the study for comparison purposes. Specific non-linear regression models described by a power function reflected relationships between Zn and Cd contents in C. rei thalli and in the host substrate in the most reliable way. The relationship for As was also noted, but none significant model was found. Contrarily, Pb concentrations in the thalli varied independently of the metal levels in the substrate. Nevertheless, the concentrations of all measured heavy metals in C. rei thalli are relatively low considering the frequently enormous substrate contamination. Different Cladonia species demonstrated a generally similar accumulation capacity and could be considered as weak accumulators. The restrained accumulation pattern may be one of the important attributes of C. rei which facilitates its colonisation of extremely contaminated dumps. This finding highlights ecological importance of this species as stable and resistant pioneer in such affected sites.