铅锌矿区农田土壤重金属有效态空间分布及其影响因子分析

利用地统计学方法,研究了广西岩溶地区某铅锌矿区农田土壤中Cd、Zn、Pb、Cu四种重金属有效态含量的空间分布特征及其影响因子.结果表明:研究区域不同程度地受到Cd、Zn、Pb、Cu的污染,且水田污染较旱地严重;与广西土壤背景值相比,污染程度最严重的是Cd,在水田和旱地中超标率均为100%,平均超标倍数分别为312.94和33.67;其次是Zn,在水田和早地中超标率分别为100%和34%,平均超标倍数分别为38.34和2.11;污染最轻的为Cu,超标率仅为7%.空间分析表明,有效态Cd、Zn、Pb、Cu的块金系数分别为2.7%、0.2%、6.5%、0.13%,体现了强烈的空间自相关性,且四种重金属空间分布特征相似,在离原铅锌选矿厂较近的西北偏西面有效态Cd、Zn、Pb、Cu含量最高,沿着西北偏西至东南偏东的灌溉渠流向,有效态Cd、Zn、Pb、Cu的含量呈递减趋势,东部旱地有效态Cd、Zn、Pb、Cu含量相对较低.土壤有效态Cd、Zn、Pb、Cu在污染区的空间分布与土壤基本理化性质关系密切,有效态Cd、Zn、Pb、Cu与pH、阳离子交换量、粘粒都呈极显著负相关,与有机质含量则呈极显著正相关.     

Sorption of heavy metals on organic and inorganic soil constituents

Sorption of heavy metals to organic matter and mineral soil constituents can hardly be separated experimentally. Here we studied the retention capacity of organic matter and minerals from soils in a long-term field experiment in which the organic carbon content had been altered, but the mineral phase had remained constant over time. The sorption of Cu, Cd and Zn showed a non-additive contribution of soil organic matter and minerals to the sorption capacity of soil. Sorption on organic matter exceeded mineral sorption from 6 to 13 times. This is the first time that sorption to soil organic matter is quantified in bulk soils.     

Heavy-metal fractionation and distribution in soil profiles short-term-irrigated with sewage wastewater

Six soil profiles irrigated and non-irrigated with sewage wastewater were investigated for soil pH, electrical conductivity (EC), organic matter (OM), and CaCO₃. The distributions and chemical fractions of Cu, Zn, Cd, and Pb, and their lability were also studied. The results indicated that pH, EC, OM, and CaCO₃, as well as metal fractionation in soil profiles were affected by wastewater irrigation, especially in the surface layer. The surface layer (0-15 cm) irrigated with wastewater exhibited a 0.6 unit decrease in soil pH, a 40.6% decrease in CaCO₃, and a 200% increase in EC as compared with that of the non-irrigated soil. The soil OM increased from 0.04% to 0.35% in the surface layer. The irrigation of soil with wastewater resulted in transformation of metals from the carbonate fraction (CARB) towards the exchangeable (EXCH), Fe-Mn oxide (ERO), and organic (OM) fraction for Zn, towards the EXCH, the OM, and residual fraction for Cu, and towards the exchangeable (EXCH) fraction for Cd. It was concluded that the use of sewage wastewater led to salt accumulation and an increase in the readily labile fraction of Zn, Cu, and Cd in the surface layer. Therefore, this reason may limit the use of wastewater under arid and semi-arid conditions.     

污染土壤中有机质结合态重金属的研究

用物理与化学相结合的方法研究了2个污染土壤剖面中有机质结合重金属（Cd、Cu、Pb和Zn）的分布，把有机质相结合态重金属分为颗粒状有机质（POM）结合的重金属和与细土腐殖质结合的重金属。结果表明，土壤POM对重金属有明品的富集作用，其中〉2mmPOM重金属Cd、Cu、Pb和Zn的富集系数分别在1．4～3．2、2．5～2．6、2．8—3．9和3．0～3．9之间；而0．05～2mmPOM重金属Cd、Cu、Pb和Zn的富集系数分别在2．7～7．8、3．2～6．4、3．2～9．3和3．2～5．6之间，0．05～2mmPOM组分中重金属的平均富集高于〉2mmPOM组分。POM中重金属的富集程度与土壤重金属的积累呈正相关。有机质结合态重金属占土壤重金属总最的比例随土壤有机质积累而增高，表土层约40％以上的重金属以有机质结合态存在。     

溶解性有机物对土壤中重金属环境行为的影响

为揭示在溶解性有机物（DOM）作用下土壤中重金属的吸附和迁移规律并确定迁移数学模型,通过不同条件下的等温吸附实验和土柱淋滤实验,研究了溶解性有机物对重金属Cu,Cd,Pb,Zn在褐土中吸附和迁移行为的影响。结果表明DOM对Cu和Cd在土壤中的吸附促进作用较明显,对Pb有微弱的促进作用,对Zn的吸附影响不明显;随着pH的改变,25℃下Cu在土壤中的吸附高于15℃和35℃条件下。DOM质量浓度越高,Cd、Zn溶出的促进效果越明显,Cu、Pb则恰好相反。DOM对土壤中Cd、Zn的垂直迁移起着促进作用,而对Cu、Pb迁移起着一定的抑制作用;DOM对土壤重金属的平均迁移量随时间的延长而减少。此迁移模型能够定量计算并预测重金属质量浓度的时空分布。     

淋洗脱盐对滨海滩涂不同植被演替带土壤重金属的影响

为研究围垦对滨海滩涂土壤重金属的影响,采用土柱实验模拟淋洗脱盐过程,分析了滨海滩涂不同植被演替带(光滩、互花米草滩、碱蓬滩、芦苇滩)土壤在淋洗脱盐前后重金属(As、Hg、Cd、Cr、Pb、Cu、Zn)含量的变化,评估了围垦可能导致的滩涂重金属流失量。研究表明,淋洗脱盐后,各植被演替带土壤重金属均显著降低,相比而言,Hg、Cr更易淋洗(淋洗率分别为57.2%、49.9%),而Zn不易淋洗(淋洗率18.5%);不同植被演替带土壤重金属淋洗率表现为:光滩互花米草滩碱蓬滩芦苇滩,光滩土壤重金属更易淋洗,而芦苇滩重金属不易淋洗;根据土壤容重、含水率、淋洗率及重金属含量计算重金属流失量发现,不同植被演替带重金属流失量同样表现为:光滩互花米草滩碱蓬滩芦苇滩;除互花米草滩As流失量较高外(19.26 kg·ha-1),其他重金属流失量均表现为光滩最高,光滩围垦可能会造成更多的重金属流失;在仅考虑淋洗脱盐情况下,以江苏省2010~2020年围垦规划270万亩计,仅表层20 cm滩涂土壤,通过围垦即可能导致As、Hg、Cd、Cr、Pb、Cu、Zn流失2 102.5、7.4、421.3、8 587.9、4 376.3、2 404.3 t,由围垦导致的滩涂重金属流失风险值得关注。     

天津污灌区土壤重金属污染环境质量与环境效应

污水作为天津解决农业用水不足的手段已经有几十年的历史。文章分析了污灌区土壤一作物系统中Cd、Hg、As、Cu、Pb、Zn和Cr等有毒重金属的质量分数，利用单因子污染指数法和加权综合污染指数法进行污染评价。评价结果表明污灌区土壤受到了严重污染，主要重金属污染元素为Cd、Hg；农作物中的主要超标元素为Cd、As。因此，污灌区重金属污染土壤的修复工作迫在眉睫。     

不同来源重金属污染的土壤对水稻的影响

采用人工污染土壤、尾矿砂、污泥等不同载体的污染源来模拟土壤污染 ,研究其对水稻生长、吸收养分和吸收重金属的影响。结果表明 ,不同污染载体对水稻生长的影响不同 ,其影响的大小顺序为人工污染土壤 >尾矿砂 >污泥 >尾矿砂 +污泥。不同污染载体对水稻吸收重金属的影响亦不同 ,以纯化学试剂的形式添加到土壤中的重金属最易被提取出来 ,植物从中吸收的Cu、Zn、Pb、Cd最多 ,而从以污泥为污染载体的土壤中吸收的Zn、Pb、Cd最少。研究表明 ,用添加纯化学试剂的方法来模拟污染土壤对生态与环境的影响是可行的 ,确定土壤负载容量是安全的 ,因为在实验条件下它对供试植物的影响最明显     

Heavy metal contamination of soil,and bioaccumulation in vegetables irrigated with treated waste water in the tropical city of Varanasi,India

The present study was conducted to determine the heavy metal contamination in soil with accumulation in plants in waste water irrigated areas. Results revealed that waste water contained lower concentrations of Cr, Zn, Cu, and Pb except Cd (0.03) than the permissible limits prescribed by the World Health Organization. The maximum metal concentrations occurred in Brassica oleracea (Zn 63.80, Cu 12.25, Cr 10.65, Pb 3.63, and Cd 0.56 mg Kg^?1).The metal enrichment (EF of Cd 1.9, Cr2.9, Zn 4.8, Cu 6.5, and Pb 15.5) and degree of contamination (CF of Cd 2.9, Cr 2.0, Zn 2.3, Cu 2.7, and Pb 2.2) showed that accumulation of the five toxic metals increased during sewage irrigation as compared with the reference values, other Indian regions and globally. However, based on WHO standards for heavy metal contamination of soil and irrigation water, our data does not ensure safe levels for food.     

Eco-friendly approach for leaching out heavy metals from sewage sludge

Sewage sludge contains rich organic matter and nutrients essential for the growth of plants but the presence of toxic heavy metals restricts its land application. To overcome this, the study aims an eco-friendly approach for leaching out heavy metals. Sewage sludge from sewage treatment plant, Chennai, India was characterised. The analysis of total heavy metal concentration was done by digesting in nitric acid and different forms were extracted by community bureau of reference sequential method. Heavy metals: As, Cd, Cr, Cr, Ni, Pb and Zn were determined using inductively coupled plasma optical emission spectrometry Perkin Elmer Optima 5300 DV. The experimental set-up for heavy metal leaching was held for five consecutive days at different concentrations of humic acid (0.1%, 0.5% and 1%) at varied pH (5–9). Results revealed that at the end of fifth day at pH 8, 1% humic acid is capable of leaching out 75.5% cadmium, 66.0% nickel, 52.0% lead, 51.2% zinc, 31.2% copper and 8.5% cadmium from sewage sludge. Statistically positive correlation (0.7088) existed between the percentage of heavy metals leached out and the sum of soluble and reducible fractions. Thus, from ecological point of view, humic acid can be used to leach out heavy metals from sewage sludge serving the need in restoration of soil fertility upon land application.     

改性污泥对矿区铜、镉污染土壤的修复

城市污泥的重金属含量超标是限制其资源化利用的主要瓶颈,论文采用石灰＋硫粉＋生物淋滤的方法去除重金属,制备改性污泥,探讨其对矿区Cu、Cd污染农田土壤的修复效果,以期实现以废治污的目标。供试水稻土采自江西某矿区附近农田,土壤Cu和Cd的TCLP（Toxicity characteristic leaching procedure）浸出量分别为40.34 mg·kg-1和660.1μg·kg-1,其中Cu的质量分数超过国际标准值15 mg·kg-1。通过室内土培的方法,将改性污泥分别按土重的0%、1%、3%、5%和10%施入供试土壤培养30 d后,分析土壤Cu和Cd的活性、形态变化以及土壤蛋白酶和脲酶活性等指标评价改性污泥对污染土壤的修复效果及作用机理。结果表明,改性污泥对土壤Cu产生显著的钝化作用,且各施用量对Cu的有效态含量表现出显著差异。当改性污泥的用量为土重的5%时,Cu的有效态含量降至12.03 mg·kg-1,低于国际标准。改性污泥对土壤Cd的钝化效果相对较弱。当改性污泥的用量为1%时,土壤Cd的活性反而有所增加。当改性污泥的用量为5%时,Cd的活性显著降低,土壤Cd的浸出量降至539.6μg·kg-1。土壤重金属形态分析的结果表明,土壤Cu主要以碳酸盐结合态、有机结合态和残渣态存在。改性污泥用量增加,可交换态Cu含量下降,当改良剂用量为土重的5%时,可交换态Cu由8.10%降至4.10%。相反,有机结合态Cu含量由26.45%增加至32.34%。土壤的可交换态Cd含量由36.80%降至30.69%。说明施用改性污泥,土壤可交换态Cu、Cd向有机结合态发生转化。土壤蛋白酶和脲酶的活性变化能较好地指示修复效果,且土壤脲酶的指示效果优于蛋白酶。     

外源铅铜镉在长三角和珠三角农业土壤中的转化

选择了我国经济发达地区的长江三角洲和珠江三角洲10个代表性农业土壤，采用室内培养和化学分级方法研究了加入外源铅、铜、镉在土壤中的动态变化及转化趋势，探讨了碳酸钙、粉煤灰、猪粪和钢渣等土壤改良剂对土壤重金属形态的影响。结果表明，随着土壤重金属负荷的提高，土壤中交换态重金属的比例增大，残余态比例下降，有效性提高，对环境威胁增大。当重金属加入最较低时，重金属优先向氧化物结合态、有机质结合态转化；而当加入最较高时，向交换态和碳酸盐结合态转化的比例明皿增加。pH和土壤组分对重金属在土壤中的转化有显著的影响，土壤pH下降可使交换态Cd、Cu、Pb的比例递增。加入碳酸钙、粉煤灰、猪粪和钢渣等改良剂可显著地降低土壤中交换态重金属比例，增加其它形态的重金属比例。     

有机酸与表面活性剂联合作用对土壤重金属的浸提效果研究

重金属污染土壤的原位淋洗修复既要实现对重金属的高效去除,还要尽量减少对土壤性质的破坏,这一点在农业污染土壤修复中尤为重要。以张士污灌区农田土壤为研究对象,利用振荡浸提技术筛选有机酸和表面活性剂组合,并确定了两者联合淋洗修复污染土壤的最佳配比。结果表明：有机酸（酒石酸、乙酸、柠檬酸和苹果酸）中的酒石酸浓度为0.5 mol.L-1和表面活性剂（SDBS、鼠李糖和皂素）中的皂素质量分数为0.7%时对土壤Cd、Pb、Zn的浸提效果较好;在酒石酸与皂素体积配比为1∶1时,对重金属Cd、Pb、Zn浸提效果最好,浸提率分别为87.62%、36.30%、20.67%;单一有机酸、表面活性剂或者有机酸与表面活性剂的混合溶液,对土壤重金属的浸提效果均为Cd〉Pb〉Zn。虽然有机酸与表面活性剂联合浸提效果略低于酒石酸浸提,但其弱酸性对土壤性质影响较小,在原位淋洗修复工程中有较好的应用前景。     

Combining potassium chloride leaching with vertical electrokinetics to remediate cadmium-contaminated soils

This study evaluated the feasibility of combining potassium chloride (KCl) leaching and electrokinetic (EK) treatment for the remediation of cadmium (Cd) and other metals from contaminated soils. KCl leaching was compared at three concentrations (0.2%, 0.5%, and 1% KCl). EK treatment was conducted separately to migrate the metals in the topsoil to the subsoil. The combined approach using KCl leaching before or after EK treatment was compared. For the single vertical EK treatment, the removal of Cd, lead (Pb), copper (Cu) and zinc (Zn) from the topsoil (0–20 cm) was 9.38%, 4.80%, 0.95%, and 10.81%, respectively. KCl leaching at 1% KCl removed 84.06% Cd, 9.95% Pb, 4.34% Cu, and 19.93% Zn from the topsoil, with higher removal efficiency than that of the 0.2% and 0.5% KCl leaching treatments. By combining the KCl leaching and EK treatment, the removal efficiency of heavy metals improved, in particular for the 1% KCl + EK treatment, where the removal rate of Cd, Pb, Cu, and Zn from the upper surface soil reached 97.79%, 17.69%, 14.37%, and 41.96%, respectively. Correspondingly, the soil Cd content decreased from 4 to 0.21 mg/kg, and was below the Chinese standard limit of 0.3 mg/kg soil. These results indicate that 1% KCl + EK treatment is a good combination technique to mitigate Cd pollution from contaminated soils used for growing rice and leafy vegetables.

     

Biosolids application affects the competitive sorption and lability of cadmium,copper, nickel,lead, and zinc in fluvial and calcareous soils

The objective of this research was to investigate the effects of biosolids on the competitive sorption and lability of the sorbed Cd, Cu, Ni, Pb, and Zn in fluvial and calcareous soils. Competitive sorption isotherms were developed, and the lability of these metals was estimated by DTPA extraction following their sorption. Sorption of all metals was higher in the fluvial than in the calcareous soil. Sorption of Cu and Pb was stronger than that of Cd, Ni, and Zn in all soils. Biosolids application (2.5%) reduced the sorption of all metals especially Cu and Pb (28–43%) in both soils (especially the calcareous soil) at the lower added metal concentrations (50 and 100 mg L^?1). However, it increased the sorption of all metals especially Pb and Cu in both soils (especially the calcareous soil; 15.5-fold for Cu) at the higher added concentrations (250 and 300 mg L^?1). Nickel showed the highest lability followed by Cd, Zn, and Pb in both soils. Biosolids increased the lability of the sorbed Ni in the fluvial soils at all added concentrations and the lability of Cd, Pb, and Zn at 50 mg L^?1, but decreased the lability of Cd, Pb, and Zn at 250 and 300 mg L^?1 in both soils. We conclude that at low loading rate (e.g., 50 mg L^?1) biosolids treatment might increase the lability and environmental risk of Cd, Cu, Pb, and Zn. However, at high loading rate (e.g., 300 mg L^?1) biosolids may be used as an immobilizing agent for Cd, Cu, Pb, Zn and mobilizing agent for Ni.     

典型城市污染水体底泥中重金属形态分布和相关性

采用Tessier五步连续提取法,研究了南京市莫愁湖、玄武湖、秦淮河13个底泥样品中的重金属的形态分布情况,分析了重金属浸出量与各形态间的相关性及有机质与有机结合态的相关性,并通过红外谱图分析了有机质与重金属结合的机理.结果表明:底泥中Pb,cu,zh,Ni,Cr主要以有机结合态和残渣态俘在,两种形态的含量占总量70%以上,Zn和Cd的可交换态和碳酸盐结合态含量相列较高,Zn约占20%,Cd约占30%;Zn,Cu,Cd,Ni,Cr的浸出量均与可交换离子态呈现显著的相关性,因此可通过减小可交换离子态含量控制底泥重金属污染的风险性;研究还表明,有机质与有机结合态呈现显著的正相关,因此增加底泥中有机质含量有助于重金属向有_棚结合态转化,有机质与重金属的结合主要是由于其中-些官能团和重金属形成稳定的络合物.     

Enrichment and solubility of trace metals associated with magnetic extracts in industrially derived contaminated soils

Magnetic fractions (MFs) in industrially derived contaminated soils were extracted with a magnetic separation procedure. Total, soluble, and bioaccessible Cr, Cu, Pb and Zn in the MFs and non-magnetic fractions (NMFs) were analyzed using aqua regia and extraction tests, such as deionized water, toxicity characteristic leaching procedure (TCLP), and gastric juice simulation (GJST) test. Compared with the non-magnetic fractions, soil MFs were enriched with Fe, Mn, Pb, Cd, Cr, Cu, and Ni. Extraction tests indicated that soil MFs contained higher water, TCLP, and GJST-extractable Cr, Cu, Pb, and Zn concentrations than the soil NMFs. The TCLP-extractable Pb concentration in the MFs exceeded the USEPA hazardous waste criteria, suggesting that soil MFs have a potentially environmental pollution risk. Solubility of trace metals was variable in the different extraction tests, which has the order of GJST?>?TCLP?>?water. TCLP test showed Cu and Zn were more mobile than Cr and Pb while bioaccessibility of trace metal defined by GJST test showed the order of Cu?≈?Cr?≈?Zn?>?Pb. These findings suggested that the MFs in the industrially derived contaminated soils had higher possibility of polluting water bodies, and careful environmental impact assessment was necessary.     

Modelling the potential mobility of Cd,Cu, Ni,Pb and Zn in Mollic Fluvisols

European floodplain soils are frequently contaminated with potentially toxic inorganic substances. We used a multi-surface model to estimate the aqueous concentrations of Cd, Cu, Ni, Pb and Zn in three Mollic Fluvisols from the Central Elbe River (Germany). The model considered complexation in solution and interactions with soil organic matter (SOM), a clay mineral and hydrous Al, Fe and Mn oxides. The amounts of reactive metals were derived from extraction with 0.43 M HNO₃. Modelling was carried out as a function of pH (soil pH ± 1.4) because it varies in floodplain soils owing to redox processes that consume or release protons. The fraction of reactive metals, which were dissolved according to the modelling, was predominantly <1%. Depending on soil properties, especially pH and contents of SOM and minerals of the clay fraction, the modelled concentrations partially exceeded the trigger values for the soil–groundwater pathway of the German soil legislation. This differentiation by soil properties was given for Ni, Pb and Zn. On the other hand, Cd was more mobile, i.e., the trigger values were mostly exceeded. Copper represented the opposite, as the modelling did not predict exceeding the trigger values in any horizon. Except for Pb and partially Zn (where oxides were more important), SOM was the most important adsorbent for metals. However, given the special composition and dynamics of SOM in mollic horizons, we suggest further quantitative and qualitative investigations on SOM and on its interaction with metals to improve the prediction of contaminant dynamics.     

Sewage sludge ditch for recovering heavy metals can improve crop yield and soil environmental quality

• Indirect use of sludge in ditches alongside plants was tested in field experiments. • The dried and stabilized sludge in ditches was recovered with heavy metals. • Cd, Pb, Cu and Zn in the planted soil were all in a safe range. • The indirect use of sludge increased plant yield, soil N content and C storage. The treatment and disposal of municipal sewage sludge (MSS) is an urgent problem to be resolved in many countries. Safely using the nutrients within MSS to increase crop yield and enhance the fertility of poor soil could contribute to achieving sustainable development. An indirect use of MSS in ditches alongside Pennisetum hybridum plants was studied in field plots for 30 months and the contents of heavy metals and macronutrients were monitored in soil, sludge and plant samples. We found that the yield of P. hybridum was significantly increased by 2.39 to 2.80 times and the treated plants had higher N content compared with no sludge. In addition, the organic matter (OM) and N contents in the planted soil increased significantly compared with the initial soil. The OM content in the planted soil of the MSS treatment was 2.9 to 5.2 times higher than that with no sludge, and N increased by 2.0 to 3.8 times. However, MSS had no significant effect on the N, P and K contents in the soil at the bottom of the MSS ditch, and the content of heavy metals (Cd, Pb, Cu and Zn) were also within the safe range. Moreover, the moisture content and phytotoxicity of MSS after this indirect use were reduced and the heavy metal contents changed little, which is favorable to the further disposal of recovered MSS. Therefore, this indirect use of MSS is beneficial to agricultural production, soil quality and environmental sustainability.     

Metals and organic components of sewage and sludges

Sewage and sludge samples were collected from rural areas of Vellore district. The metals like Cu, Zn, Cd, Pb, Fe, Ca and Mg were determined by Inductively coupled plasma atomic emission spectrophotometry (ICP-AES). For this determination HCl - HNO3 and 4N HNO3 extracts were used. The total organic carbon (TOC), chemical oxygen demand (COD) and organic matter (OM) have also been determined to evaluate the presence of organic and metallic contents in sewage and sludge environment.