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1.
The results of long-term studies of the contents of bulk forms of metals (Cu, Zn, Fe, Ni, Pb, Mn, Co, and Cd) and their mobile compounds in soils of background and human-disturbed areas within the Krasnoural’sk–Sibai–Gai copper–zinc and Baimak–Buribai mixed copper mineralization zones in the Bashkir Transural region are discussed. It is shown that soils of the region are characterized by abnormally high natural total contents of heavy metals (HMs) typomorphic for ore mineralization: Cu, Zn, and Fe for the Sibai province and Cu, Zn, and Ni for the Baimak province. In the case of a shallow depth of the ores, the concentrations of HMs in the soils are close to or higher than the tentative permissible concentration values. The concentrations of mobile HM compounds in soils of background areas and their percentage in the total HM content strongly vary from year to year in dependence on weather conditions, position in the soil catenas, species composition of vegetation, and distance from the source of technogenic contamination. The high natural variability in the content of mobile HM compounds in soils complicates the reliable determination of the regional geochemical background and necessitates annual estimation of background parameters for the purposes of the ecological monitoring of soils. The bulk content of Cu and Zn content in soils near mining enterprises exceeds the regional geochemical background values by 2–12 times and the tentative permissible concentrations of these metals by 2–4 times. Anthropogenic contamination results in a sharp rise in the content of mobile HM compounds in soils. Their highest concentrations exceed the maximum permissible concentrations by 26 times for Cu, 18 times for Zn, and 2 times for Pb. Soil contamination in the impact zone of mining enterprises is extremely dangerous or dangerous. However, because of the high temporal variability in the migration and accumulation of HMs in the soils, the recent decline in the ore mining activities, and the construction of purification facilities, no definite temporal trends in the contents of HMs in the soils have been found in the studied region for the period from 1998 to 2015.  相似文献   

2.
Biochar (BC), known as the new black gold, is a stable, novel carbonaceous by-product that is synthesized through pyrolysis of biological materials in the absence of O2. Recently, an emerging interest in the application of BC as a robust soil amendment has given rise to a broad research area in science and technology. It is considered a promising remediation option for heavy metal (HM)-contaminated soils to reduce HM bioavailability to plants. Remediation efficacy of BC depends on the porosity, composition, pyrolysis temperature, feedstock, and residence time of pyrolysis. This review article aimed to present an overview of BC use in the immobilization of HMs, i.e., Cd, As, Pb, Zn, Ni, Cu, Mn, Cr, and Sb, in contaminated soils. The remaining uncertain factors, including the specific soil HM immobilization mechanisms, long-term beneficial effects, and potential environmental risks associated with BC application are analyzed. Future research must be conducted to ensure that the management of environmental pollution is in accord with ecological sustainability and adaptation of the black gold biotechnology on a commercial basis for immobilization of HMs in contaminated soils.  相似文献   

3.
Qualitative and quantitative studies of the kinetics and dynamics of technogenic migration of heavy metals (HMs) have been performed in laboratory experiments. It is shown that the redistribution of HMs applied into soils in neutral form has an impulsive pattern. Soil texture does not have a decisive influence on the migration capacity of metals. An important feature of the technogenic migration of HMs is the effect of the polymetallic contamination, upon which the migration capacity of a set of heavy metals is higher than that of separate metal compounds. An index characterizing the ratio of absolute values of migration rates of ionic forms of metals estimated from electrical conductivity values to the rate of infiltration of the soil solution (vm/vf) is suggested to estimate the kinetics of HM migration in soils.  相似文献   

4.
The effect of natural and technogenic factors on the mobility and transformation of metal compounds was studied from an analysis of the fractional-group composition of Cu, Zn, and Pb compounds in the soils of areas adjacent to the Novocherkassk power station. Changes in the composition of Cu, Zn, and Pb compounds in the soils of technogenic landscapes were estimated. The effect of aerosol technogenic emissions on the mobility of metal compounds was revealed; a higher metal mobility was found in soils with low buffering capacity. Common and specific features of the formation of Cu, Zn, and Pb compounds in soils were determined. The role of individual soil components in the retention of metals in clean and contaminated soils was established.  相似文献   

5.
不同高粱种质对污染土壤中重金属吸收的研究   总被引:2,自引:0,他引:2       下载免费PDF全文
利用重金属含量较高的污水污染土壤,以未污染土壤作对照,种植8个甜高粱品种、2个饲用高粱品种和1个粒用高粱品种,检测8种重金属在高粱植物体内不同器官的含量,以研究不同高粱种质对重金属的吸收特性。结果表明:甜高粱对汞(Hg)、镉(Cd)、锰(Mn)和锌(Zn)的吸收在两种土壤间差异显著,对钴(Co)、铬(Cr)、铅(Pb)和铜(Cu)的吸收差异不显著。Mn在甜高粱体内含量表现为未污染土壤高于污染土壤;而Zn含量在不同器官之间存在差异,未污染土壤叶中含量远高于穗,穗中含量远高于茎和根。不同重金属在甜高粱体内的储存部位不同,污染土壤上Hg、Cd、Co、Cr和Zn在根中积累量较高,Cu、Mn和Pb在穗中的积累量较高。甜高粱、饲用高粱和粒用高粱对重金属的吸收、运输及储存在品种之间差异较大,同一品种对不同重金属的吸收也存在差异。饲用高粱表现为叶部对Cr和Zn的储存量较高,而粒用高粱‘晋中0823’则显示了茎对多种重金属的储存能力。高粱根对土壤中重金属的富集系数较高,为0.02(Pb)~0.23(Cd),转移系数变幅为0.21(Co)~3.42(Pb)。对同一种重金属的吸收量品种间差异较大,甜高粱‘西蒙’根对Co、Cr、Cu、Mn、Pb和Zn具有高富集系数,粒用高粱‘晋中0823’茎对Hg、Cd、Mn、Pb和Zn富集系数较高。高粱对重金属的吸收能力与转移能力不同步,甜高粱‘绿能1号’具有对多种重金属的高转移能力,粒用高粱‘晋中0823’只对Zn有较高的转移能力。因此本文认为甜高粱对不同重金属的吸收和转移有选择性。对Zn吸收并转移到地上部后,首先储存在叶和穗中,当吸收量足够大时,茎和根也成为储存器官;对Mn的吸收与其他重金属的吸收存在竞争作用,Hg吸收后很少向地上部转移;而对Cu、Mn和Pb吸收后在穗部的储存量较大。饲用高粱与甜高粱相比对重金属的吸收未显示明显的不同,甜高粱‘西蒙’根对多种重金属具有强储存能力,而粒用高粱‘晋中0823’的茎秆显示了比甜高粱更强的储存能力,甜高粱‘绿能1号’对多种重金属的转移能力较强。所以,选择富集和转移能力均强的高粱品种能更有效地吸收土壤中的重金属,达到修复污染土壤的目的。  相似文献   

6.
Combined approach for fractioning metal compounds in soils   总被引:1,自引:1,他引:0  
A combined approach for fractioning metal compounds in soils on the basis of sequential and parallel extractions is proposed. This approach has been used to assess the group composition of Zn, Cu, and Pb compounds in an ordinary chernozem and its changes upon the soil contamination with metals. The contents of firmly and loosely bound metal compounds that are presumably fixed by the particular soil components (organic substances, carbonates, and silicate and nonsilicate minerals) have been determined.  相似文献   

7.
The data on the fractional composition of the heavy metal (HM) compounds in the plow horizon of a loamy-sandy soddy-podzolic soil investigated by different methods of fractionation are presented. The use of the BCR (Community Reference Bureau) scheme did not fully allow revealing some regularities governing the state of the copper, zinc, nickel, and lead in the soil. This system does not reflect the existing ideas concerning the interaction between the HMs and soil components. The chemical properties of the elements are manifested more distinctly when the scheme of the HM fractionation elaborated in our country is used. Despite some disadvantages, the method of chemical fractionation of metal compounds permits one to obtain adequate and useful information on the state of the microelements and HMs in soils.  相似文献   

8.
Natural and technogenic compounds of heavy metals in soils   总被引:1,自引:0,他引:1  
The existing geological classification of heavy metals (HMs) is not suitable for their characterization in soils. The carriers of HMs in soils differ from those in the lithosphere. These are clay minerals; iron oxides, whose composition varies between the background and urban soils; various manganese oxides; and different groups of organic substances. The mineral composition of HM carriers can vary significantly. The main iron oxides are ferrihydrite, goethite, feroxyhyte, and lepidocrocite in the background soils and technogenic magnetite in the urban soils. The different structures of manganese oxides determine their affinity for specific HMs. Metallic iron and green rust are very efficient in artificial geochemical barriers, although they act as strong reducers there. HM compounds strongly vary in soils because of the unstable conditions.  相似文献   

9.

Purpose

The main purpose of this study was to evaluate temporal and regional variability of contamination by heavy metals (HMs) in river sediments using their enrichment factors (EFs) and benchmarking according to sediment quality guidelines (SQGs). The Zlin region in the Czech Republic (Morava and Drevnice River basins) represents a model area where several regionally specific ecological risk assessment studies have recently been conducted with a focus on organic pollution, eco-toxicity, geological, and geochemical characteristics.

Materials and methods

Four consecutive sediment sampling campaigns were undertaken in spring and autumn 2005–2006. Aqua-regia leachable content of Cd, Co, Cr, Cu, Ni, Pb, Sb, V, and Zn in surface sediments from 14 sites was analyzed using ICP-MS, and Hg content was analyzed using AMA-254 analyzer. EFs were calculated to identify the human impact on pollution in the area. Comparisons to SGQs were conducted to identify the areas and HMs of greatest risk.

Results and discussion

Calculation of EFs contributed to the effective clustering of HMs. Median EFs of Co, Ni, and V ranged from 0.9 to 1.4 at all sites indicating concentrations very close to natural geological background levels. There was greater enrichment at locally polluted sites, the highest in the cases of Cd, Sb, Hg, and Cr. Widespread influence of diffuse HM sources (traffic, agriculture, and urban wastes) was apparent from elevated concentrations of Pb, Cu, and Zn at all sites. EF values also helped to identify the greatest temporal changes and shifts in HMs contamination between adjacent sites caused by 50-year recurrence interval floods in early spring 2006. The impact was most apparent in downstream sites; namely directly below the confluence of the two major rivers.

Conclusions

The overall contamination of HMs in the region was classified as low-to-moderate with significantly contaminated sub-areas. The study showed relatively stable spatial distributions of HMs, indicating potential sources of pollution. Cu was identified as the HM of greatest risk. The study emphasizes the necessity of considering both environmental circumstances and background HM occurrence to prevent misinterpretation of the pollution situation. The use of EFs which include grain size proxy normalization and HM background levels, along with the comparison of the detected concentrations to SQGs, proved an efficient way to identify hazardous contamination from anthropogenic sources.  相似文献   

10.
Background, aim, and scope  Heavy metal (HM) mobility in soil depends on the HM species in it. Therefore, knowledge of the HM speciation in soil allows the prediction of HM impact on the environment. HM speciation in soil depends on the metal chemical origin, soil texture, and other factors such as the origin and level of soil contamination. Recently, the problem of organic waste utilization is of great importance as the amount of this recyclable material is continually increasing. One of the possible ways of recycling is the use of processed organic wastes for agricultural needs. In this research, aerobically composted sewage sludge was used, the utilization of which is of essential importance. But one of the most serious restrictions is HM transfer from such material to the soil. Therefore, a prediction of HM mobility in soil and its migration in the environment is an important issue when using sewage sludge compost (SSC) in agriculture. Zn, Cu, and Pb speciation was performed according to the modified methodology of Tessier et al. (Anal Chem 51:844–851, 1979) in two different (sandy and clay) soils with background HM amounts and in soil samples amended with aerobically digested SSC to find out the predominant species of the investigated HM and to predict their potential availability. Materials and methods  The modified method of sequential extraction initially proposed by Tessier et al. (Anal Chem 51:844–851, 1979) is designed for HM speciation into five species where HM mobility decreases in the order: F1—exchangeable HM (extracted with 1 M MgCl2 at an initial pH of 7 and room temperature), F2—carbonate-bound HM (extracted with 1 M CH3COONa buffered to pH 5 at room temperature), F3—Fe/Mn oxide-bound HM (extracted with 0.04 M NH2OH·HCl at an initial pH of 2 at 96°C), F4—organic matter-complexed or sulfide-bound HM (extracted with 0.02 M HNO3 and 30% (v/v) H2O2 at a ratio of 1:1 and an initial pH of 2 at 85°C), and F5—the residual HM (digested with HNO3, HF, and HCl mixture). After digestion, HM amounts in solution were determined by atomic absorption spectrometry (AAS ‘Hitachi’). Mixtures of uncontaminated soils of different textures (clay and sandy) with SSC in ratios 20:1, 10:1, and 5:1 were used to simulate the land application with SSC. During a period of 7 weeks, changes in Zn, Cu, and Pb content within species were investigated and compared weekly in soil–SSC mixtures with their speciation in pure soil and in the SSC. Results  Results in the SSC showed that more HM were found as mobile species compared to the soils, and in sandy soil, more were found in the mobile species than in clay soil. But the HM speciation strongly depended on the metal chemical origin. According to the potential availability, HM ranked in the following order: Zn>Pb>Cu. Zinc generally occurred in the mobile species (F1 and F3), especially in sandy soils amended with SSC, and changes of the Zn speciation were insignificant at the end of the experiment. Pb transfer to insoluble compounds (F5) was evident in the SSC–soil mixtures. This confirms that Pb is extremely immobile in the soil. However, the observed increase of Pb amounts in the mobile species (F1 and F2) during the course of experiment shows a critical trend of Pb mobilization under anthropogenic influence. Copper in the soil–SSC mixtures had a trend to form compounds of low mobility, such as organic complexes and sulfides (F4) and nonsoluble compounds (residual fraction F5). Initially, the amounts of mobile Cu species (F1 and F2) increased in the soils amended with SSC, probably due to the influence of SSC of anthropogenic origin with lower pH and high organic matter content, but Cu mobility decreased nearly to the initial level again after 3–4 weeks. Hence, the soil has a great specific adsorption capacity to immobilize Cu of anthropogenic origin. Discussion  Zn mobility and environmental impact was greater than that seen for Cu and Pb, while mobility of both Cu and Pb was similar, but variable depending on soil texture and contamination level. The effect on the shift of HM mobility and potential availability was greater in sandy SSC-amended soils than in clay soils and increased with an increasing amount of SSC. Conclusions  Usage of SSC for land fertilization should be strictly regulated, especially regarding Pb amounts. Recommendations and perspectives  The influence of SSC on Cu and Zn mobility and potential availability was more significant only in the case of sandy soil with a higher SSC ratio. Nevertheless, this waste product of anthropogenic origin increased Pb mobility in all cases in spite of only moderate Pb mobility in SSC itself. Therefore, aerobic processing of sewage sludge must be strictly regulated, especially regarding Pb amounts, and SSC ratios must be in control regarding HM amounts when using it for on-land application.  相似文献   

11.
Heavy metals (HMs) and antibiotic resistance have become serious environmental problems affecting soil and human health. Soil microorganisms play key roles in pollutant degradation and biogeochemical cycling processes; however, the interactions among HMs, soil microbial communities, and antibiotic resistance genes (ARGs) in agricultural soils remain unclear. Using quantitative real-time polymerase chain reaction and NovaSeq sequencing, we evaluated heavy metal contents, abundances of ARGs, soil bacterial community structure and functions, and their correlations in paddy soils at 43 sampling sites along the middle and lower reaches of the Yangtze River, central and eastern China. Our results showed the co-occurrence of HMs, ARGs, and HM resistance genes across all paddy soils. Additionally, significant positive associations were detected between HMs and resistance genes. Cadmium, czcA, and int1 were positively correlated with bacterial community diversity. The Mantel test showed that bacterial community composition and functions were significantly associated with HMs and resistance genes, such as Cd, Cr, Zn, copA, czcA, int1, and sul1. Moreover, HMs and ARGs were the major factors shaping soil bacterial communities; thus, HMs triggered proliferation of HM and antibiotic resistances by influencing the mobile genetic element (int1) and soil microbial communities. Our study revealed that HMs potentially drive the co-selection of ARGs by shifting soil bacterial community structure and functions, thereby increasing the potential risks to human health as well as ecological environment in the paddy soils along the middle and lower reaches of the Yangtze River.  相似文献   

12.
The accumulation of heavy metals (HMs) in soils is the most often cited potential risk of compost application. As the ecological effects of metals are related to mobile fractions rather than to total concentrations in the soil, we measured the total (aqua regia–extractable) HM concentrations, the readily available water‐soluble and the potentially bioavailable LiCl‐extractable fraction of soil HMs in a field experiment after 10 y with total applications of 95, 175, and 255 t ha–1 biowaste compost (fresh matter). Total soil concentrations of Cd, Cr, Cu, Ni, and Pb in the compost treatments were not significantly higher than in the unfertilized control. Total Zn concentrations increased in the treatment with the highest application rate, as expected from the calculation of the Zn load in the composts. In the mobile fractions, as measured in soil saturation extract and LiCl extract, Cd and Pb were not detectable. Concentrations of Cr, Ni, and Zn were in the range published for unpolluted soils in other studies and did not show any differences according to treatment. Easily exchangeable Cu (in LiCl extract) was increased with compost fertilization, most probably due to complexation with low‐molecular organic complexants. Except for Cd and Zn, the results of the mobile HM fractions in the soil were in good agreement with plant HM concentrations. In conclusion, fertilization with high‐quality biowaste compost at such rates and after 10 y of application gives no cause for concern with regard to both total HM concentrations and available HM fractions.  相似文献   

13.
The applicability of phytoextraction to remediate soils contaminated with heavy metals (HMs) depends on, amongst others, the duration before remediation is completed. The impact of changes in the HM content in soil occurring during remediation on plant uptake has to be considered in order to obtain a reliable estimate of the phytoextraction duration. To simulate the decrease in the HM content in soil and to assess the resulting decrease in the uptake of HMs by plants, contaminated soil was mixed with uncontaminated, but otherwise similar soil. Uptake of Cd, Pb, and Zn by the indicator plant Lupinus hartwegii and the Zn hyperaccumulator Thlaspi caerulescens (La Calamine ecotype) was a log-linear function of the in-situ measured HM soil solution concentrations. Over a wide range in dissolved Cd and Zn concentrations, uptake of these HMs by T. caerulescens was (much) greater than by L. hartwegii. Experimentally derived regression models describing the relationships between soil, soil solution, and plant were implemented in a HM mass balance model used to obtain estimates of the phytoextraction duration. For our target soils, estimates of the Cd phytoextraction duration using L. hartwegii or T. caerulescens increased significantly by more than 100 or 50 years when experimental soil—soil solution—plant relationships were used instead of the assumption of constant plant uptake of Cd. The two approaches gave similar results for phytoextraction of Zn by T. caerulescens.  相似文献   

14.
淮南粉煤灰处置场周围土壤中若干金属污染调查   总被引:4,自引:0,他引:4  
通过系统采集高皇和上窑两个贮灰场周围土壤样品,采用ICP-AES分析方法,调查土壤中若干金属元素(Cd、Cr、Cu、Mn、Ni、Pb、Zn)含量,评价淮南市三大热电厂大体积粉煤灰长期处置导致土壤金属污染状况。结果表明:这些元素在土壤中表现积累性富集,Cu、Cd、Cr具有相对高的迁移性。但土壤金属含量除Cu外,均没有超过国家土壤一级质量标准,土壤属无污染或轻微污染类型。因此,有效处置管理措施能够控制淮南粉煤灰中有害金属的环境影响。  相似文献   

15.
ABSTRACT

In

-situ sorbent amendment is a relatively low-cost, low-impact approach for remediation of soil contaminated with heavy metals (HMs), and thus is considered a way to be favored in developing countries. In this study, materials of non-hazardous, alkaline agronomic and industrial by-products were used as sorbents to explore their capacity of in situ immobilization of multiple HMs in mining-impacted arable soil. These sorbents included fly ash (FA), biochar (BC) and apatite (AP) and they were implemented with varying ratios of combinations. Results of soil microcosm tests showed that after incubation for 90 days, concentrations of Pb, Zn, and Cd in their exchangeable forms determined by a sequential extraction method significantly decreased in amended soils, as opposed to the unamended control. Of the five sets of amendments, the composite of FA, BC, and AP resulted in the maximum reduction (up to 80%) in the mobility of Pb, Zn, and Cd in soils. The mechanisms underlying the immobilization of HMs in amended soils might involve processes of surface precipitation, ion exchange and complexation, in which the physicochemical properties of sorbent materials played an important role. The immobilization efficacy of sorbent amendments on HMs in soil was further supported by pot experiments in which significant inhibition of HM accumulation in the belowground and aboveground tissues of maize was observed after 50-day cultivation in amended soils as compared with control soil. Together, these results suggest that the application of cost-saving and environmentally friendly materials derived from wastes as sorbents to remediate soils contaminated with multiple HMs is promising for developing countries like Vietnam.  相似文献   

16.
Background, Aim and Scope   Humic acids (HAs) are the most important humified component of dissolved organic carbon (DOC) present in sewage water used for irrigation. It is well known that HAs affect the toxicity and availability of heavy metals (HMs) in soil-plant systems, and may increase the human exposure to HMs in contaminated soil through plant uptake. This study was conducted to assess the effects of HAs on HM availability, plant growth and HM uptake. Materials and Methods: With wheat (Triticum aestivum) as a test plant, a greenhouse pot experiment was conducted to investigate the effects of HAs in irrigation water on the phytoavailability of cadmium (Cd) and lead (Pb) in soil. Cd and Pb were added to the soil at concentrations of 1.5 and 150 mg/kg, respectively. Wheat seedlings grown in Cd and Pb-contaminated soil were watered with 4 levels of HA solution (0, 140, 280 and 560 mg/kg of HAs, respectively). Results: In control and Pb treatments, both plant biomass and plant HM concentrations increased with increasing concentrations of HAs in the solution. Plant biomass was markedly decreased when metal concentrations in plants increased, particularly in Cd and Cd/Pb treatments. In the soil, extractable metals, and water soluble organic carbon (WSOC) and its fractions significantly increased with increasing HA concentrations. Discussion: The results suggested that the application of HAs in barren soils may improve plant nutrition by mobilizing soil nutrients and providing plants with carbon sources. On the other hand, HAs present in sewage water may increase both the availability and transfer of HMs in the soil-plant continuum and subsequently increase human exposure to HMs in polluted soil. Conclusions. Conclusions: HA solution as irrigation water significantly increased HM availability to plants cultivated in the HM-amended soil and may increase the environmental risk of sewage irrigation. Recommendations and Perspectives: These results suggested that, when assessing the effect of sewage irrigation on soil quality, HAs contained in sewage water should be taken into consideration.  相似文献   

17.
ABSTRACT

Today, soil metal pollution has become a significant environmental issue of great public concern. This is because soil is both a major sink for heavy metal(loid)s (HMs) released into the environment, by both pedogenic and anthropogenic activities; and also a major source of food chain contamination mainly through plant uptake and animal transfer. In addition, HM contamination of soil leads to negative impacts on soil characteristics and function by disturbing both soil biological and physiochemical properties (e.g. extreme soil pH, poor soil structure and soil fertility and lack of soil microbial activity). This eventually leads to decreased crop production. Various soil remediation techniques have been successfully employed to reduce the risks associated with HMs efflux into soil. Among these, the use of low-cost and environmentally safe inorganic and organic amendments for the in-situ immobilization of HMs has become increasingly popular. Immobilization agents have successfully reduced the availability of metal ions through a variety of adsorption, complexation, precipitation, and redox reactions. Soil amendments can also be a source of nutrients and thus can also act as a soil conditioner, improving the soil’s physiochemical properties and fertility, resulting in enhanced plant establishment in metal contaminated soils. This article critically reviews the use of immobilizing agents in HM contaminated agricultural and mining soils paying particular attention to metal immobilization chemistry and the effects of soil amendments on common soil quality parameters.  相似文献   

18.
Heavy metals (HMs) in domestic sewage sludge, applied to land, contaminate soils. Phytoremediation is the use of plants to clean‐up toxic HMs from soil. Chelating agents are added to soil to solubilize the metals for enhanced uptake. Yet no studies report the displacement of HMs in soil with sludge following solubilization with chelates. The objective of this work was to determine the uptake or leaching of HMs due to a chelate added to a soil from a sludge farm that had received sludge for 25 y. The soil was placed in long columns (105 cm long; ?? 39 cm) in a greenhouse. Columns either had a plant (hybrid poplar; Populus deltoides Marsh. × P. nigra L.) or no plant. After the poplar seedlings had grown for 144 d, the tetrasodium salt of the chelating agent EDTA was irrigated onto the surface of the soil at a rate of 1 g per kg of soil. Drainage water, soil, and plants were analyzed for three toxic HMs (Cd, Ni, Pb) and four essential HMs (Cu, Fe, Mn, Zn). At harvest, extractable and total concentrations of each HM in the soil with EDTA were similar to those in soil without EDTA. The chelate did not affect the concentrations of HMs in the roots or leaves. With or without plants, EDTA mobilized all seven HMs and increased their concentrations in drainage water. Lower concentrations of Cd, Cu, Fe, Ni, and Zn in leachate from columns with EDTA and plants compared to columns with EDTA and no plants showed that poplars can reduce groundwater contamination by intercepting these HMs in the soil. But the poplar plants did not reduce Pb and Mn in the leachate from columns with EDTA. Concentrations of Cd and Pb in the leachate mobilized by EDTA remained above drinking‐water standards with or without plants. The results showed that a chelate (EDTA) should not be added to a soil at a sludge farm to enhance phytoremediation. The chelate mobilized HMs that leached to drainage water and contaminated it.  相似文献   

19.
Purpose

The effect of Cu, Zn, and Pb high rates on the physical properties and organic matter of Haplic Chernozem (Clayic) (A1 horizon 0–20 cm) under model experimental conditions was studied.

Materials and methods

In a model experiment, soil samples of Haplic Chernozem (Clayic) were artificially contaminated with 2000 mg/kg of Cu, Zn, and Pb acetates added separately. The particle-size fraction, the microaggregates distribution, the structural status, the total content and fractional and group composition of organic matter, physico-mechanical properties were determined in soil without metals and soil contaminated with metals.

Results and discussion

At the soil contamination with Cu, Zn, and Pb, the content of organo-mineral colloids increased, which results to the increasing of the clay fraction content by 4.5% compared to the control. The analysis of the microaggregate size composition of the studied soil shows that the content of coarser aggregates (1–0.25 mm) increases and the content of finer (0.05–0.001 mm) aggregates decreases after the addition of HMs and correspond to the HMs series: Cu → Zn → Pb. A significant decrease in the coefficient of water stability in the control from 3.0 to 1.4–1.5 in the contaminated treatments. The structural status (estimated from total agronomically valuable aggregates) changes from excellent to good. The addition of Cu, Zn, and Pb to the soil affects the quantitative composition of organic matter. The contents of free and sesquioxide-bound humic acids and free fulvic acids increased. The contamination with Zn and Pb causes the aliphatization of organic matter.

Conclusions

Under conditions of model experiment, the contamination of Haplic Chernozem (Clayic) with high rates of Cu, Zn, and Pb leads to changes of the microaggregates distribution, the structural status, and the qualitative composition of organic matter.

  相似文献   

20.
An investigation was made of the Zn, Cu, Mn, and Pb contents in samples of soil and grass collected along highways and in fields adjoining industrial zones in Belgium. Soil contamination by Zn and Pb was quite pronounced along highways and in some cases contamination by Mn was also observed. Contamination by these heavy metals decreased rapidly with increasing distance from the highway. High values of metal accumulation in plants located near highways were observed. The accumulation of Pb was particularly pronounced. Contamination by Cu, Zn, Pb and possibly Mn in soils of some urban gardens was also recorded.  相似文献   

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