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1.
One of the environmental concerns in recent decades is the prevalence of different pollutants in soil. Hence, the importance of remediation has led to the development of various methods to remediate polluted soil. Among these methods, soil washing has gained significant attention to treat polluted soils. In this paper, the response surface methodology was applied in order to determine the optimal conditions for total petroleum hydrocarbon remediation using nonionic surfactant Brij35 in soil environment. The effect of different factors in soil washing process including surfactant solution concentration and volume, washing time, age of pollution and frequency of washing are evaluated. The predicted values for total petroleum hydrocarbon remediation efficiency by the response functions are in a very close agreement with experimental data (R-2= 98.75 %). The second order model was developed as experimented response and optimal conditions were obtained by analyzing the contour and surface plots and also by solving the regression equation using LINGO 9.0 software. The optimal concentrations (8 g/L), volume of surfactant solution (500 mL), washing time (75 min), age of pollution (29 days) and frequency of washing (three times) are determined. In this optimal condition, the removal efficiency has been observed to be 93.54 % which conforms to the results of process optimization using response surface methodology. Based on the results, it can be concluded that the response surface methodology is a suitable approach to determine the optimal conditions of soil washing to remediate organic hydrophobic pollutants using the nonionic surfactant Brij35 from the soil.  相似文献   

2.
The effects of humic acid (HA) on heavy metal uptake by herbaceous plants in soil simultaneously contaminated with heavy metals and petroleum hydrocarbons were investigated. The results showed that HA reduced readily soluble and exchangeable forms of heavy metals in the contaminated soil but increased their plant-available forms. Potential bioavailability and leachability factors became larger than 1 after adding HA to the soil, except for those of Ni, suggesting that more heavy metals could be potentially phytoavailable for plant uptake. Furthermore, HA increased the accumulation of Pb, Cu, Cd, and Ni in the shoots and roots of selected plants. The greatest increase in the accumulation of heavy metals was 264.7 % in the shoot of Festuca arundinacea, with the bioconcentration factor (BCF) increasing from 0.30 to 1.10. Humic acid also increased the BCFs of the roots of Brassica campestris for Ni and Pb. These results suggest that HA amendment could enhance plant uptake of heavy metals, while concurrently reducing heavy metal leachability and preventing subsurface contamination, even in soils simultaneously contaminated with petroleum hydrocarbons.  相似文献   

3.
Surfactant-enhanced remediation of contaminated soil: a review   总被引：48，自引：0，他引：48  
Extracting aqueous solutions with or without additives are employed to solubilize contaminants in soil. Since water solubility is the controlling removing mechanism, additives are used to enhance efficiencies. These additives can reduce the time to treat a site compared to the use of water alone. Additives must be of low toxicity and biodegradable. The research in this area has focussed mainly on halogenated volatile organic compounds (VOCs) and is still quite limited for metal removal. Additives include surfactants, organic and inorganic acids, sodium hydroxide, which can dissolve organic soil matter, water-soluble solvents such as methanol, displacement of cations with nontoxic ones, complexing agents such as EDTA, acids in combination with complexing agents or oxidizing/reducing agents. Cationic, anionic and nonionic surfactants are particularly used for soil washing or flushing. They contain both hydrophobic and hydrophilic portions, making them ideal for solubilization of hydrophobic compounds. Numerous studies have indicated that surfactants enhance recoveries of non-aqueous phase liquids (NAPLs). There have also been indications that pretreatment of soil with surfactant washing to solubilize hydrophobic compounds such as PAHs enhances biodegradation of these contaminants. A few in situ field studies have been performed with surfactants. Large-scale treatment has been done mostly for organic removal. Soil pH, soil type, cation exchange capacity (CEC), particle size, permeabilities and contaminants all affect removal efficiencies. High clay and organic matter contents are particularly detrimental. Understanding the chemistry of the binding of the contaminant and the hydrogeology of the site are very important. Once the water is pumped from the soil, it must be extracted and then treated to remove the hydrocarbons and metals. Several technologies exist such as sodium hydroxide or sodium sulfide precipitation, ion exchange, activated carbon adsorption, ultrafiltration, reverse osmosis, electrodialysis and biological processes. Recycling of the surfactants is desired to decrease treatment costs.

This paper will provide an overview of the laboratory research, field demonstration and full-scale application of surfactants for the remediation of contaminated soil. The majority of pilot scale in situ flushing tests, particularly in the United States, have involved the use of surfactants and co-solvents. There are only a few full-scale projects however. Recent laboratory scale efforts by the authors concerning the use of biosurfactants, biologically produced surfactants, to enhance the removal of copper, cadmium and zinc from contaminated soils and sediments are discussed. Three types of biosurfactants were evaluated for their effectiveness. They included a lipopeptide called surfactin from Bacillus subtilis, a rhamnolipid from Pseudomonas aeruginosa and a sophorolipid from Torulopsis bombicola. The results indicated the feasibility of removing the metals with the anionic biosurfactants even though the exchangeable fractions were not significant.  相似文献   


4.
The objective of the present paper was to investigate the potential of urban wastes derived soluble bioorganic substances (SBO) to perform as auxiliaries for enhanced washing of urban soil contaminated by industrial activities. The second objective was to show how the SBO could be used for remediating the environmental impact caused by industrial activities and, at the same time, be compatible with the real-world situation demanding zero waste processes. The SBO, isolated from four urban biowastes, were characterized for their lipophilic/hydrophilic (LH) and aliphatic/aromatic C ratios, and for their surface activity properties. Soil, containing about 0.45 % w/w polycyclic aromatic hydrocarbons (PAHs), was sampled from a dismissed coal gasification site. The efficiency of the SBO for washing the contaminated soil was investigated. The most lipophilic SBO, in spite of the highest surface activity, was the least efficient. The products having lower LH, poorer surface activity, but higher concentration of aromatic C were more efficient. All SBO allowed developing a two steps process. This comprised soil washing, and the recovery and chemical treatment of the washing solution, to yield a PAHs–SBO precipitate and the clean water phase to recycle to further soil washing. Data were obtained under the same experimental conditions using Triton X-100 commercial surfactant. The results indicated that, although the commercial surfactant is the most efficient in the soil washing step, it does not allow removal of PAHs from the recovered washing solution. On the contrary, 95–99 % PAHs removal from the recovered SBO washing solutions is attained.  相似文献   

5.
Ulsan mine produced the iron ore minerals of magnetite, arsenopyrite, and scheelite in 1992, and serpentine was developed from 1977 to 2002. The soils of the mine were contaminated by heavy metals such as As, Zn, Ni, and Cd. Heavy metals of Ni and Zn came mostly from serpentinite, and As was derived mainly from arsenopyrite in the scan-type iron ore body. As, Zn, and Ni were major contaminants, but Cd was a minor contaminant on a basis of Korean standard. The heavy metals in the deep depth (>?5 m) came from the host rocks, and those in the shallow depth (<?5 m) were derived from the organic–mineral complexation soil. The remediation plan was a soil washing for highly contaminated soils and the containment of clay materials for less contaminated soils. Even though the remediation methods were successful, the continuous monitoring and the analysis of monitoring data are still necessary for the conservation of soil and groundwater around the study area.  相似文献   

6.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic pollutants in urban environments including urban soils. Elevated concentrations of PAHs in urban soils are caused by incomplete combustion of petroleum and coal. This study assesses 16 individual PAH compounds in a total of 112 surficial soil samples. The objective was to assess and compare the levels of contamination as well as examine the main sources of PAHs in four urban agricultural soils using molecular ratios of some specific hydrocarbons. The study showed that PAH levels in soil ranged from 1.23 ng/kg in soil collected from Dzorwulu to 2.95 ng/kg in soil collected from Ghana Broadcasting Cooperation (GBC) vegetable irrigation site. Of the total PAHs, the more water soluble PAHs (2–4 rings), which tend to be concentrated in the vapour phase were found to dominate the soils. The percentage dominance were Dzorwulu (52.8 %), Marine Drive (62.5 %), CSIR (53.2 %) and GBC (49.2 %). However, there were significant levels of the more carcinogenic PAHs (5–6 rings) present with percentages as 47.1, 37.5 46.8 and 50.8 % for Dzorwulu, Marine Drive, CSIR and GBC vegetable irrigation sites, respectively, and therefore, may impact negatively on public health. Based on the classification by the Institute of Soil Science and Plant Cultivation in Pulawy, Poland, urban soils in Accra could be classified as contaminated to different levels. Molecular ratios of Flu/pyr and PA/Ant were calculated to determine the main sources of PAHs. Results showed that PAHs could originate mainly from incomplete combustion of petroleum products, especially from atmospheric fallout from automobile exhausts. The study further showed that B(a)P concentration of 0.05 ng/kg in soil from GBC urban vegetable irrigation site requires immediate clean-up exercise and monitoring to mitigate human health impact.  相似文献   

7.
Industrial soil systems have become complex due to human activities, as they disturb the natural development of soil and add hazardous elements. Hence, there is a growing public concern over the accumulation of heavy metals in soil due to the rapid industrial development during the last decade in Iran. The objectives of the present study are to carry out comparative assessment of the heavy metals in soils of the Chitgar Industrial Area Tehran (Iran) with average world guidelines and to evaluate enrichment and normalized scatter coefficient. In this work the concentrations of seven heavy metals (Cr, Co, Cd, Cu, Pb, Ni and Zn) from the surface soils of the industrial area were quantified, based on 210 samples collected from 70 sampling stations in three consecutive seasons May 2007, November 2007 and May 2008 using 0.5 × l Km square mesh. Common comparison methods were employed to assess the quality of soils and guideline values were used to represent a desired level of elements. Comparison variables and enrichment factor showed that Pb has high-level value while normalized scatter coefficient demonstrates that Cd increases in soils more rapidly as compared to other elements. This study revealed that normalized scatter coefficient can be effectively used to evaluate soil pollution and is independent of the past.  相似文献   

8.
岩溶地质高背景区土壤中普遍存在的铁锰结核对重金属的赋存状态和有效性有重要影响。选择广西贵港覃塘岩溶地质高背景区富含铁锰结核的表层土壤(0~20 cm)为研究对象,筛分出不同粒径的铁锰结核(10~120目)和细粒径土壤(<120目)样品进行化学分析,针对以下三个方面开展研究:(1)重金属(As、Cd、Cr、Cu、Hg、Ni、Pb和Zn)在铁锰结核和细粒径土壤中的分布分配规律和铁氧化物矿物的组成;(2)铁氧化物矿物对富含铁锰结核的土壤中Cd等重金属富集的影响;(3)重金属在富含铁锰结核的土壤中的赋存机制。研究发现,铁锰结核中的Fe和Mn以及Cd等重金属含量随着粒径的增大而不断增加,说明Cd等重金属元素更倾向于在大粒径铁锰结核中富集;土壤中Cd等重金属总量的约90%赋存在结核中,表明研究区土壤中重金属主要以结核形式赋存;富含铁锰结核的土壤中赤铁矿和针铁矿的平均含量分别为0.61%和4.94%,且结核粒径越大,针铁矿和赤铁矿含量越高;除Hg外,Cd等重金属含量与针铁矿和赤铁矿的含量均呈现极显著正相关,与赤铁矿的相关性稍优于针铁矿,表明铁氧化物矿物与富含铁锰结核土壤中的Cd等重金属元素富集密切相关。铁锰结核的存在既能促进Cd等重金属在土壤中的富集,又能降低土壤中重金属的生物有效性,研究结果为解释岩溶地质高背景区土壤Cd等重金属元素高含量、低生物有效性提供了理论依据。  相似文献   

9.
Column bioreactors were used for studying mechanisms of metal removal, assessment of long-term stability of spent reactive mixtures, as well as potential metal mobility after treating highly contaminated acid mine drainage (AMD; pH 2.9–5.7). Several physicochemical, microbiological, and mineralogical analyses were performed on spent reactive mixtures collected from 4 bioreactors, which were tested in duplicate for two hydraulic retention times (7.3d and 10d), with downward flow over an 11-month period. Consistent with the high metal concentrations in the AMD feed, and with low metal concentrations measured in the treated effluent, the physicochemical analyses indicated very high concentrations of metals (Fe, Mn, Cd, Ni, and Zn) in the top and bottom layers of the reactive mixtures from all columns. Moreover, the concentrations of Fe (50.8–57.8 g/kg) and Mn (0.53–0.70 g/kg) were up to twice as high in the bottom layers, whereas the concentrations of Cd (6.77–13.3 g/kg), Ni (1.80–5.19 g/kg) and Zn (2.53–13.2 g/kg) were up to 50-times higher in the top layers. Chemical extractions and elemental analysis gave consistent results, which indicated a low fraction of metals removed as sulfides (up to 15% of total metals recovered in spent reactive mixtures). Moreover, Fe and Mn were found in a more stable chemical form (residual fraction was 42–74% for Mn and 30–77% for Fe) relative to Cd, Ni or Zn, which seemed more weakly bound (oxidisable/reducible fractions) and showed higher potential mobility. Besides identifying (oxy)hydroxide and carbonate minerals, the mineralogical analyses identified metal sulfides containing Fe, Cd, Ni and Zn. Metal removal mechanisms were, therefore, mainly adsorption and other binding mechanisms with organic matter (for Cd, Ni and Zn), and the precipitation as (oxy)hydroxide minerals (for Fe and Mn). After 15 months, however, the column bioreactors did not lose their capacity for removing metals from the AMD. Although the metals were immobile during the bioreactor treatment, their mobility could increase from spent reactive mixtures, if stored inappropriately. Metal recovery by acidic leaching of spent substrates at the end of bioreactor operation could be an alternative.  相似文献   

10.
氨基泡塑的合成及其应用于富集地质样品中的痕量金   总被引：3，自引：2，他引：1  
采用泡塑(PUF)富集,AAS或ICP-OES测定地质样品中痕量金是常用的分析方法。与活性炭相比,PUF的选择性好,但吸附容量偏低,可将泡塑负载不同的萃取剂或修饰不同的官能团提高吸附容量。本文将聚醚型泡塑经盐酸水解制备成氨基泡塑(PUF-NH_2)。红外光谱和扫描电镜表征显示,PUF-NH_2峰形发生了明显红移(3376.5 cm-1),其中的氨基数量显著增加,另外PUF-NH_2的高分子出现明显断裂,发生水解后裸露出的氨基具有还原性,在吸附金的过程中易与金离子在PUF-NH_2表面发生氧化还原反应,形成金纳米颗粒。改性后的PUF-NH_2吸附容量达到96 mg/g,与PUF相比提高了8倍。将PUF-NH_2应用于富集地质样品中的金,经炭化灼烧、50%王水提取后用ICP-OES测定,金的加标回收率在95.0%~105.0%之间,检出限为0.15μg/g。实验证明用PUF-NH_2处理样品提高了富集倍数和分析灵敏度,有利于低品位矿石的分析。  相似文献   

11.
王图锦  潘瑾  刘雪莲 《岩矿测试》2016,35(4):425-432
消落带是水域与陆地的过渡地带,对水环境有着至关重要的影响。本文以三峡库区消落带面积最大的澎溪河流域作为研究区域,采集消落带土壤及其沿岸土壤样品,分析重金属形态分布特征,并使用地质累积指数法和风险评价准则(RAC)对重金属污染程度及生态风险进行评价。研究表明,消落带土壤中Pb、Cu、Cr、Cd、Zn和Ni平均含量分别为68.70、36.96、55.10、0.68、108.26、31.68 mg/kg,污染程度依次为CdPbZnCuNiCr,以Cd和Pb污染较为突出,普遍高于长江干流土壤,远高于重庆地区土壤。Cd的RAC值为20.62%,呈中等环境风险;其形态稳定性最差,以可还原态和酸提取态为主。Pb、Cu、Cr、Zn、Ni的RAC值为5.45%~10.0%,环境风险较低;且均以残渣态为主,占总量的54.69%~83.05%。以消落带沿岸土壤为对照,消落带形成后土壤中各重金属总量均有不同程度升高,且不同重金属在其增量部分的形态存在差异,Cr和Ni的增量部分以残渣态为主,Cd、Pb、Zn的增量以非残渣态为主。研究发现,由于受到水域与陆地污染源的双重影响,澎溪河流域重金属具有由沿岸向消落带沉积富集的趋势。  相似文献   

12.
Ethylenediaminetetraaceticacid (EDTA) has been proven to be an efficient soil washing liquid to remove metal contaminants from soils. However, EDTA may cause secondary pollution due to its low biodegradability if it is not recycled or destroyed in the washing process. Thus, it is necessary to recycle and recover EDTA for sustainable use. In this paper, the extracting performance of fresh EDTA was firstly studied as a function of EDTA concentration, liquid/sediment (L/S) ratio and pH of the solution, and also extraction time. Then sodium tetraethylenepentamine-multi dithiocarbamate (TEPA-DTC), a heavy metals capturing agent, was synthesized on the base of the research of LIU-Lihua. Compared with Na2S and DDTC, TEPA-DTC shows strong chelating capacity, because it has functional groups of dithiocarbamate that could strongly chelate heavy metals and capture metal ions from Me-EDTA to form precipitates, allowing us to reclaim the EDTA during the process of soil washing. Three divalent heavy metals were investigated (Pb, Cd, and Cu). These three metals could almost precipitate completely with TEPA-DTC under the dosage of 300 mg/l, and EDTA was regenerated. The recovered EDTA was used again in three cycles of soil washing, and the amount of heavy metals extracted just slightly decreased each cycle.  相似文献   

13.
Theeco environmentalpollutioncausedbyminingdevelopmentisaworldwideproblem ,whichhasarousedever increasingattentionofscientists.Inadditiontovegetationdestructionanderosionofcultivatedlanddirectlycausedbyminingdevelopment,scientistshaveplacedmorefocusontheenvironmentalproblemsinducedbythereleaseofharmfulsubstances ( particularlyheavymetals) .Especiallyundersurfaceconditions,thepiled upminewastes (minetailings)undergoweatheringundertheactionofaseriesofgeochemicalfactorssuchasthemineralogyofmineta…  相似文献   

14.
对于人为因素或自然因素造成的农田土壤重金属元素污染,需要进行大面积的土壤环境质量调查和分类管控,然而传统的采样测试方法存在工作量大、代价高等问题。可见—近红外（Vis-NIR）反射光谱是一种快速低成本获取土壤理化信息的手段。为研究Vis-NIR反射光谱预测模型划分土壤重金属污染风险类别的能力,文章以典型人为污染地区（浙江温岭）和典型地质高背景地区（广西横县）的390份农田土壤为样本,测定8种重金属元素（As、Cd、Cr、Cu、Hg、Ni、Pb和Zn）的含量和pH值,并测定土壤Vis-NIR光谱。使用偏最小二乘（PLS）和支持向量机（SVM）算法建立回归模型,对土壤重金属含量和pH值进行预测,并基于预测值进行土壤重金属污染风险分类。结果显示,温岭土壤主要污染元素Cd和Cu的光谱模型回归预测偏差（RPD）分别为1.23和1.19,预测机制与有机质有关。横县土壤主要污染元素As和Cd的RPD分别为1.98和1.93,预测机制与铁氧化物和粘土矿物有关。地质高背景土壤重金属与铁氧化物的正相关性普遍较强,使得光谱模型对重金属含量预测准确度较高。温岭和横县土壤pH值的光谱模型RPD分别为1.76和1.68。土壤重金属污染风险光谱分类的总体 准确度分别为75.0%~100%（温岭）和80.0%~100％（横县）。将Vis-NIR光谱与遥感技术相结合,对农田土壤重金属污染风险进行快速分类总体是可行的。  相似文献   

15.
Consuming edible plants contaminated by heavy metals transferred from soil is an important pathway for human exposure to environmental contaminants. In the past several decades, heavy metal accumulation in contaminated soil has been widely studied; however, few researches investigated the background levels of metals in plants and evaluated the difference in plants grown in soils produced from different parent rocks. In this study, a systemic survey of heavy metal distribution and accumulation in the soil–pepper system was investigated in an unpolluted area, Hainan Island, China. Levels of Cu, Pb, Zn and Cd were measured in soils and pepper fruits from five representative pepper-growing areas with different soil parent rocks (i.e. basalt, granite, sedimentary rock, metamorphic rock and alluvial deposits). Average concentrations of Cu, Pb, Zn and Cd in pepper fruits were 11.52, 0.84, 8.77 and 0.05 mg/kg, respectively. The concentrations of heavy metals in soils are controlled by the parent materials and varied greatly from in different areas. Heavy metal contents in all pepper samples were lower than the Chinese maximum contaminant levels. The relationship between heavy metals in soils and biological absorption coefficient (BAC) of pepper fruits suggests that the uptake ability of pepper for soil metals depends mainly on the physiological mechanism, while in some cases, the soil types and supergene environment are also important.  相似文献   

16.
Various extraction procedures were employed for measuring extractable concentrations of potential toxic elements in soil. The extractability of Cd, Cu, Pb and Zn in four contaminated and four non-contaminated soils of Japan, was compared by single extraction (CaCl2, DTPA, NH4Cl, 0.1 M HCl and 1 M HCl ) and sequential extraction procedures [(six operationally defined chemical phases, viz. water soluble (Fl), exchangeable (F2), carbonate (F3), oxide (F4), organic (F5) and residual (F6) fractions)]. Extractability of metals from soils samples varied depending on metals and/or extradants used. Among the extradants, 1 M HCl extracted the largest proportion of Cd (79 to 96% of total), Cu (61 to 83%), Pb (51 to 99%) and Zn (23 to 52%) from soils followed by 0.1 M HCl, NH4Cl, DTPA and CaCl2. In all the extradants, the proportion of extractability of metals was higher in the contaminated soils than the non-contaminated soils. Regardless of soils and extradants, relative extractability was higher for Cd as compared to other three metals. The use of 1 M HCl may be recommended for first-level screening of soil contamination with heavy metals. The other four weak extradants are believed to provide a better assessment of bioavailable/mobile metals content in soils than 1 M HCl extradant. However, 0.1 M HCl mobilized all four metals irrespective of soil types, therefore, might be the best choice if only one extradant is to be used. The sequential extraction procedures showed 22 to 64% of total Cd was in the mobile fraction (sum of Fl to F3), while the corresponding values for Cu, Pb and Zn in this fractions were 2 to 23% suggesting higher mobility of Cd than other three metals. The single extraction procedures are simple and easy to perform and obtained results are comparable with sequential extraction procedure.  相似文献   

17.
Heavy metals in tailings and mining wastes from abandoned mines can be released into adjacent agricultural field and bioaccumulated in crops or vegetables. Therefore, prediction of metal bioavailability has become an important issue to prevent adverse effect of bioaccumulated metals on human health. In this study, single and sequential extraction methods were compared using multivariate analysis to predict the bioavailability of Cd and As in contaminated rhizosphere soils. Single extraction using 0.1 M HCl for Cd and 1.0 M HCl for As had an extraction efficiency of 8–12% for soil Cd and 14–17% for soil As compared to total concentration extracted with aqua regia. Using sequential extraction, Fe–Mn-bound Cd (FR3) and residual Cd (FR5) were the dominant fractions representing 43 and 41% of total Cd concentration. For As, the strongly absorbed form (FR2) was the most abundant chemical fraction showing 45–54% of the total As concentration in soil. Multivariate analyses showed that single extraction with HCl and total concentration of Cd and As in soil were significantly correlated to potato and green onion plant tissue metal concentration. Although little information was obtained with multiple regression analysis because of multicollinearity of variables, the result of principle component analysis (PCA) revealed that the highest positive loading was obtained using total concentration of Cd and As in soil in the first principle component (PC1). In addition, total concentration of Cd and As in soil was independently grouped with other chemical fractions by cluster analysis. Therefore, the overall result of this research indicated that total concentrations of Cd and As in rhizosphere soils were the best predictors of bioavailability of heavy metals in these contaminated soils.  相似文献   

18.
小秦岭金矿区土壤重金属生物有效性与影响因素   总被引：1，自引：0，他引：1  
张开军  魏迎春  徐友宁 《地质通报》2014,33(8):1182-1187
土壤中重金属生物有效性与影响因素分析是土壤重金属风险管控的关键问题。通过实地调查、现场采样、实验测试、综合分析等方法,分析了研究区100km2内Hg、Pb、Cd、Cr、As、Cu、Zn七种重金属元素的有效态含量特征,研究了这些重金属有效态含量之间、有效态含量与全量、有效态与土壤pH、有机质含量、粒度等基本理化参数之间的相关性,分析了重金属污染来源。结果表明,土壤中Hg、Pb、Cd、Cr、As、Cu、Zn七种重金属有效态的平均含量分别为2.29mg/kg、594mg/kg、2.52mg/kg、6.30mg/kg、2.16mg/kg、48.14mg/kg、50.21mg/kg,其变异系数大小为:HgPbCuZnCdAsCr。Hg的变异系数最大,是由于金矿选矿活动采用混汞法提金排放的尾矿堆(库)分布不均。Hg、Pb、Cd、Cu、Zn有效态量与全量之间均存在显著的相关性;土壤有机质与重金属有效态之间存在显著的相关性;土壤pH与有效态重金属之间存在显著的负相关性;土壤粒度对重金属有效态的累积影响不明显。  相似文献   

19.
Studies on seasonal changes of heavy metal concentration in soils provide vital information for best management options at all times. The study investigated temporal variation in concentration of heavy metals in three towns having automobile service centres in Imo State. The study site is characterized by two major seasons in a year. Heavy metals were found in both arable and automobile soils, but more concentrations were recorded on the latter. Mean values of Cd, Cr, Ni, Hg and Pb were 6.2 mg/kg, 4.7 mg/kg 6.5 mg/kg, 0.02 mg/kg and 71.9 mg/kg respectively in the dry season while 2.9 mg/kg Cd, 2.2 mg/kg Cr, 1.9 mg/kg Ni, 0.01 mg/kg Hg and 51.9 mg/kg Pb were recorded during the rainy season of the experimental period. Higher values of heavy metal concentration were found in automobile soils as follows: 18.1 mg/kg Cd, 12.0mg/kgCr, 16.3 mg/kg Ni, 4.8 mg/kg Hg and312.8 mg/kg Pb in rainy season, and 15.1 mg/kg Cd, 8.1 mg/kg Cr, 11.9 mg/kg Ni 2.7 mg/kg Hg and 267.9 mg/kg Pb. However, Cd showed highest variability in arable soils during the dry season (CV=79%) while Hg varied widely in automobile soils in the rainy season (CV=54%).  相似文献   

20.
洪涛  谢运球  赵一  杨利超 《中国岩溶》2016,35(4):439-445
为探讨硫铁矿冶炼区不同土地利用方式和土壤类型对重金属元素迁移的影响,采集了毕节市林口废弃硫铁矿冶炼厂内耕地砂壤土及附近林地石灰土表层和深层样共40组。室内测试土壤理化指标Pb、Zn、Cd全量和有效态含量,并对重金属元素含量的水平和垂直分布特征及重金属元素含量的相关性进行了讨论。结果表明:土壤中Pb和Zn的含量均符合土壤环境质量二级标准值,耕地表层土壤Cd含量是贵州省农业土壤背景值的7倍。土壤Cd有效态含量占全量的比值最大,而Pb和Zn有效态含量占全量的比值差别较小。耕地砂壤土Zn和Cd的全量随剖面深度的增加表现为先增大后减小,Pb呈减少的趋势;Pb和Zn的有效态含量随剖面深度的增加而减少,Cd有效态含量呈波动变化。林地石灰土中Pb、Zn、Cd的全量和有效态含量均随剖面深度的增加而减少,且Pb、Zn、Cd全量之间及全量与有效态含量之间都具有显著的正相关关系,而在耕地中各元素的相关性不明显。土壤频繁的扰动和偏酸性的环境有利于重金属垂向迁移。   相似文献   

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