海南岛砖红壤中铅、镉的化学形态与转化

采用土培实验和连续提取.原子吸收分光光度法,研究了重金属Pb、Cd在海南岛花岗岩砖红壤中的形态组成、外源Pb、Cd污染及化学修复剂磷、钙、硫对土壤重金属形态的影响.结果表明:在供试原土壤中,重金属Pb的化学形态以结合态和残余态为主,土壤有效态Pb含量较低,其中残余态Pb>有机质结合态Pb>铁锰氧化物结合态Pb>碳酸盐结合态Pb>交换态Pb>水溶态Pb,说明土壤Pb的环境风险较低;重金属Cd的化学形态以铁锰氧化物结合态和碳酸盐结合态为主,土壤中交换态Cd含量较高,其中铁锰氧化物结合态Cd>碳酸盐结合态Cd>交换态Cd>有机结合态Cd>残余态Cd>水溶态Cd,说明土壤Cd的环境风险较高.当外源Pb、Cd污染土壤时,有铁锰结合态Pb>残余态Pb>有机态Pb>碳酸盐结合态Pb>交换态Pb>水溶态Pb,交换态Cd>铁锰氧化物结合态Cd>碳酸盐结合态Cd>残余态Cd>有机态Cd>水溶态Cd的趋势.向污染土壤施加化学改良剂过磷酸钙、硫化钠和石灰,能显著降低水溶态Pb、Cd和交换态Pb、Cd的含量,并使有机结合态Pb、碳酸盐结合态Pb和铁锰氧化物结合态Pb含量下降,但残余态Pb、碳酸盐结合态Cd、铁锰氧化物结合态Cd和有机态Cd有增加的趋势,残余态Cd的含量基本稳定.     

河北主要土壤中Cd和Pb的形态分布及其影响因素

采用网室盆栽试验和大田取样 ,运用连续提取方法 ,研究了河北平原潮土和潮褐土两种土壤中Cd、Pb的化学形态特征及与其影响因素的关系。结果表明 :随着Cd、Pb污染程度的增加 ,其交换态有增加趋势。当高浓度重金属污染土壤时 ,Cd(潮土 >1mgkg- 1、潮褐土 >5mgkg- 1)主要以交换态存在 ,并表现为 :交换态 >碳酸盐结合态 >铁锰氧化物结合态 >有机结合态 >残留态 ;Pb主要以碳酸盐结合态和铁锰氧化物结合态存在。在低浓度重金属污染的土壤中 ,Cd (潮土 <1mgkg- 1、潮褐土 <5mgkg- 1)的残留态、有机结合态成倍增加 ,甚至超过交换态 ,表现为 :残留态 >碳酸盐结合态 >有机结合态 >交换态 >铁锰氧化物结合态 ;Pb主要以铁锰氧化物结合态和残留态存在。Cd、Pb在土壤中的分布与土壤的pH值 ,有机质含量密切相关。     

泉州走马埭典型土壤重金属的赋存形态分析

采用改进的Tessier连续萃取方法研究了泉州走马埭国家农田示范保护区典型土壤中重金属(Cr、Ni、Cu、Zn、Cd、Pb)的化学形态分布,通过土壤重金属的赋存形态分析比较了6种重金属的生物可利用性。研究结果表明,土壤中不同重金属元素化学形态分布具有不同的特点:Cr和Ni主要以残渣态存在,其余形态所占的比例很小;Cu以残渣态含量最高,碳酸盐结合态含量最低;Zn以残渣态为主,可交换态含量最低;Cd以可交换态和碳酸盐结合态为主,水溶态含量最低;Pb以残渣态和铁锰氧化物结合态为主,水溶态含量最低。土壤中除Cd外,Zn、Cu、Cr、Pb、Ni在正常自然条件下相对比较稳定。     

珠江三角洲城郊菜地耕层土壤中Cd、Pb赋存形态及其相互关系

选取珠江三角洲典型区域城郊菜地41个耕层土壤样品,采用化学形态分级-连续提取法研究了土壤中Cd、Pb赋存形态,通过统计分析,揭示了菜地耕层土壤Cd、Pb形态分布特征及其相互关系。Cd赋存形态平均含量顺序为:铁锰氧化物结合态(32.4%)≥碳酸盐结合态(27.2%)≥交换态(21.0%)>残渣态(10.4%)>有机态(9.0%);Pb则为:残渣态(54.1%)>铁锰氧化物结合态(27.5%)>有机态(11.6%)>碳酸盐结合态(4.6%)>交换态(2.1%)。非残渣态Cd占各形态Cd总和的平均比例(89.6%)明显高于Pb(45.9%)。碳酸盐结合态Cd分别与铁锰氧化物结合态Cd、有机结合态Cd呈极显著正相关和显著正相关(前者r=0.8482,P<0.01;后者r=0.4090,P<0.05),但与残渣态Cd呈极显著负相关(r=-0.5343,P<0.01),铁锰氧化物结合态Cd和有机结合态Cd分别与残渣态Cd呈极显著正相关(前者r=0.6965,p<0.01;后者r=0.5379,P<0.01);铁锰氧化物结合态Pb与残渣态Pb呈极显著正相关(r=0.5217,P<0.01),但有机结合态Pb却与残渣态Pb呈显著负相关(r=-0.3252,P<0.05)。在散点图矩阵的基础上建立了曲线估计的回归方程,用之可预测土壤中交换态Cd、Pb的大致数量及植物有效性。     

Effect of pH on chemical forms and plant availability of cadmium,zinc, and lead in polluted soils

The effect of pH on chemical forms and plant availability of heavy metals in three polluted soils was investigated. The soils were adjusted to pH values of 7.0, 6.0, and 4.5, then sequentially extracted so that Cd, Zn, and Pb could be partitioned into five operationally defined chemical fractions: exchangeable, carbonate, Fe-Mn oxide, organic, and residual. Kidney beans were grown in the soils to investigate plant availability of the metals in relation to changes of their levels in chemical forms resulting from alteration of soil pH. Alteration of pH resulted in changes of chemical forms of the metals in the soils, and at lower pH the changes were more significant. When soil pH values were decreased from 7.0 to 4.55, levels of Cd, Zn, and Pb in exchangeable form increased, decreased in carbonates and decreased slightly in Fe-Mn oxide forms. Their levels in organic and residual forms were unchanged. Although concentration of metals in plants increased with reduction in soil pH values, dry matter yields were also restricted, so that the amount of metal uptake were almost similar. The uptake rate of the metals in the exchangeable + carbonate forms was the same for the three elements in all the cases.     

Forms of Cd,Cu, Pb,and Zn in soil and their uptake by cereal crops when applied jointly as carbonates

The cereal crops (barley -Hordeum vulgare L., maize -Zea mays L., wheat -Triticum vulgare L.) were grown in a greenhouse using a sandy soil type treated with various doses of cadmium carbonate (salt), copper carbonate (malachite), lead carbonate (cerussite), and zinc carbonate (smithsonite), added jointly. The following levels of these metals were used: Cd ? 5, 10, 50μg g^?1 soil; Cu and Pb - 50,100, 500 μg g^?1 soil; Zn-150, 300, 1500 μg g-1 soil. Sequential extraction was adopted to partition the metals into five operationally-defined fractions: exchangeable, carbonate, Fe-Mn oxides, organic, and residual. The residual was the most abundant fraction in the untreated (control) soil for all the metals studied (50 to 60% of the total metal content). The concentrations of exchangeable Cd, Cu, Pb, and Zn were relatively low in untreated soil but increased (over the three year period) in treated soils for Cd, Zn, and Cu, whereas only small changes were observed for Ph. This experiment showed a significant increase in Cd, Zn, and Cu in tissue of plants grown on the treated soil, but a non-significant change in plant tissue with respect to Pb concentration.     

吉林西部土壤砷的形态分布及其与土壤性质的关系研究

按照生态地球化学土壤样品元素形态分析方法,将土壤无机砷分成水溶态、离子交换态、碳酸盐态、腐植酸结合态、铁锰氧化物结合态、强有机结合态和残渣态。通过对吉林西部36个表层土壤样品的测试,分析了土壤不同形态砷的分布和不同形态砷与土壤性质的关系。研究表明,洮南市不同形态砷的分布为：残渣态（65．30％）〉腐植酸结合态（17．39％）〉铁锰氧化物结合态（10．70％）〉碳酸盐态（2．23％）〉水溶态（2．17％）〉强有机结合态（1．17％）〉离子交换态（1．04％）。通榆县不同形态砷的分布为：残渣态（56．66％）〉腐植酸结合态（23．82％）〉铁锰氧化物结合态（11．08％）〉碳酸盐态（2．81％）〉水溶态（2．18％）〉离子交换态（1．98％）〉强有机结合态（1．46％）。残渣态砷是吉林西部土壤砷的主要形态。土壤水溶态砷和铁锰氧化物结合态砷与土壤pH值皆呈极显著正相关;残渣态砷与土壤有机质皆呈极显著负相关,而与土壤阳离子交换量呈极显著正相关。离子交换态砷、碳酸盐态砷、铁锰氧化物结合态砷和强有机结合态砷与土壤矿质元素的关系不大,而水溶态砷、腐植酸结合态砷和残渣态砷与土壤矿质元素的关系密切。     

水稻子实对不同形态重金属的累积差异及其影响因素分析

在分析成都平原核心区土壤重金属(Cd、Cr、Pb、Cu、Zn)全量、各形态含量及相应点位种植的水稻子实重金属含量的基础上,通过统计分析、空间插值及线性回归方程的模拟,研究了土壤Cd、Cr、Pb、Cu、Zn全量的空间分布状况、各形态重金属含量统计特征,以及水稻子实对重金属各形态的累积差异及其影响因素。结果表明,成都平原水稻土重金属污染较轻,除Cd外,均低于国家土壤环境质量二级标准。土壤中重金属的可交换态含量均较低,Cd主要以铁锰氧化态存在,Cr、Cu、Zn、Pb主要以残渣态存在。水稻子实对5种重金属的累积效应顺序为:Cd>Zn>Cu>Pb>Cr。与水稻重金属累积关系密切的重金属活性形态(可交换态、碳酸盐结合态、铁锰氧化物结合态和有机物结合态)主要有:Cd的碳酸盐结合态、Cr的可交换态、Pb的有机物结合态和Cu的碳酸盐结合态含量;Zn各活性形态对水稻子实含量的影响不明显。土壤理化性质对不同活性形态重金属元素的影响效应各不相同。活性态Cd主要受有机质、pH和容重的影响;活性态Cr与pH、有机质、CEC和容重密切相关;活性态Pb与有机质、容重、中细粉粒、砂粒等均有密切的关系;Cu的活性主要受粘粒、有机质含量的影响;Zn的有效性主要受pH、有机质、砂粒、容重的影响。总的看来,对土壤Cd、Cr、Pb、Cu、Zn各活性形态含量影响效应较强的是有机质、pH、容重,而与土壤吸附性能密切相关的颗粒组成、CEC的影响不甚明显。     

有机质对冻融黑土重金属Zn赋存形态的影响

冻融作用对不同有机质含量的土壤重金属Zn赋存形态转化产生显著影响,以24h为1个冻融周期,对150mg(Zn)·kg-1的黑土冻融8次,结果表明,随着有机质含量的增加,未经冻融土壤的交换态和铁锰氧化物结合态Zn含量逐渐降低,有机结合态Zn含量逐渐增加,残渣态Zn含量变化不显著。冻融作用可促进交换态和铁锰氧化物结合态Zn含量降低,促进有机结合态和残渣态Zn含量增加。随着土壤有机质含量的增加,冻融作用使重金属Zn生物有效态含量降低。通过有机质含量与各形态Zn含量拟合,在未冻融和冻融条件下,各形态Zn含量与有机质含量之间呈二次多项式的函数关系,相关系数r2在0.664和0.995之间。     

Forms of trace metals from inorganic sources in soils and amounts found in spring barley

Barley (Hordeum vulgare L.) was grown on a sandy soil given different doses of cadmium carbonate (salt), copper carbonate (malachite), lead carbonate (cerussite), and zinc carbonate (smithsonite) in a pot experiment conducted in a greenhouse. The element compounds were added to the soil in amounts equivalent to the following levels of the metals: Cd 5, 10, 50 μq ^?1; Cu and Pb 50, 100, 500 μg g^?1; Zn 150, 300, 1500 μg g^?1. Sequential extraction was used for partition these metals into five operationally-defined fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and residual. The residue was the most abundant fraction in the untreated soil for all the metals studied (43 to 61% of the total contents). The concentration of exchangeable Cd (0.2 μg g^?1), Cu (0.01 μg g^?1), Pb (0.1 μg g^?1), and Zn (1.4 μg g^?1) were relatively low in the untreated soil but increased markedly in the treated soils for Cd (up to 31 μg g^?1) and Zn (up to 83 μg g^?1), whereas only small changes were observed for Cu and Pb. The pot experiment showed a significant increase in the Cd and Zn contents of barley grown on the treated soils, but only small changes in Cu and Pb concentrations.     

砂姜黑土中重金属Cu、Cd、Zn形态分布与土壤酶活性研究

采用小麦农田取样,对土壤中的重金属运用连续提取方法,研究了皖北砂姜黑土中Cu、Cd、Zn的化学形态特征及其与四种土壤酶(过氧化氢酶、脲酶、蔗糖酶、中性磷酸酶)活性间的关系。结果表明:在砂姜黑土中,残留态Cu、Cd、Zn在总量中所占比例很高,交换态、有机态、碳酸盐结合态含量明显低于残留态。在三种元素中,Zn的化学形态变化趋势最为一致,表现为残留态>碳酸盐结合态>铁锰结合态>有机态>交换态;砂姜黑土中交换态Cu、Cd、Zn对脲酶活性有显著抑制作用,有机态Cu、Cd、Zn对过氧化氢酶表现为一定程度的促进作用。因此,在砂姜黑土壤中,把交换态Cu、Cd、Zn和脲酶以及中性磷酸酶的活性共同作为评价土壤Cu、Cd、Zn污染程度的主要生化指标是可行的。     

外源铅在土壤中的形态、分布及其对土壤养分的影响

通过对加入外源铅的砂姜黑土、黄褐土、红壤进行培养处理,测定土壤中各形态铅及水溶态NH4 ,K 和速效态磷的含量,研究外源铅在各类土壤中的形态分布特点及对土壤养分的影响。结果表明:交换态和残渣态的铅为红壤>黄褐土>砂姜黑土,碳酸盐态铅为砂姜黑土>黄褐土>红壤,铁锰氧化态铅为红壤>砂姜黑土>黄褐土,有机结合态铅为黄褐土>砂姜黑土>红壤;交换态和残渣态所占比例随着外源铅的浓度增大而提高,有机结合态的比例随着外源铅浓度增大降低,碳酸盐结合态铅在砂姜黑土、铁锰氧化态铅在红壤上则呈现外源铅小于500 m g/kg时比例增高,大于500 m g/kg时比例开始下降的状况;加入外源铅的土壤中,水溶态的NH4 和K 的浓度增大,使其流失的风险性增加;水溶态磷和铅离子生成难溶性磷酸铅盐被固结,使速效磷的浓度减少,降低了水溶性磷肥的功效。     

膨润土和沸石在镉污染土壤治理中的应用

采用通过盆栽试验,研究了膨润土和沸石对镉污染土壤的治理效果。结果表明,施加膨润土后不同污染程度土壤的交换态、碳酸盐结合态镉的质量分数都有所下降,铁锰氧化物结合态、有机结合态和残渣态镉的质量分数则有所上升。沸石和膨润土对轻度、中度镉污染土壤都表现出钝化作用,对重度镉污染土壤,膨润土对镉的钝化效果明显,而沸石却起到了激活镉的作用。在不同程度镉污染土壤上,膨润土可增加乌塌菜的生物量,并可抑制其对镉的吸收,降低乌塌菜植株体内镉的浓度,对乌塌菜的生长具有显著的促进作用。沸石对轻度和中度镉污染土壤均可降低乌塌菜植株体内镉的浓度,促进乌塌菜的生长并增加其生物量;对重度镉污染土壤,沸石对乌塌菜的生长影响较小,乌塌菜植株体内镉的积累显著增加。     

膨润土和沸石在镉污染土壤治理中的应用

采用通过盆栽试验,研究了膨润土和沸石对镉污染土壤的治理效果。结果表明,施加膨润土后不同污染程度土壤的交换态、碳酸盐结合态镉的质量分数都有所下降,铁锰氧化物结合态、有机结合态和残渣态镉的质量分数则有所上升。沸石和膨润土对轻度、中度镉污染土壤都表现出钝化作用,对重度镉污染土壤,膨润土对镉的钝化效果明显,而沸石却起到了激活镉的作用。在不同程度镉污染土壤上,膨润土可增加乌塌菜的生物量,并可抑制其对镉的吸收,降低乌塌菜植株体内镉的浓度,对乌塌菜的生长具有显著的促进作用。沸石对轻度和中度镉污染土壤均可降低乌塌菜植株体内镉的浓度,促进乌塌菜的生长并增加其生物量;对重度镉污染土壤,沸石对乌塌菜的生长影响较小,乌塌菜植株体内镉的积累显著增加。     

Estimation of maximum permissible levels of cadmium in a light soil by using cereal plants

A pot experiment was conducted in a greenhouse to establish the threshold level of Cd in a light soil planted with cereals. During three consecutive years barley, wheat, rye, and corn were grown in the soil treated with 2.5; 5; 25 g g^–1 of Cd applied in sulphate form. The Cd concentration of 5 g g^–1 (plus native Cd content of the soil) was considered as the maximum permissible Cd level in a soil for the soil-plant systems studied. Besides the estimation of total Cd concentrations, several forms of Cd in soils (exchangeable, carbonate, Fe-Mn oxides, organic, and residual) were determined by mean of sequential extraction to define the phytoavailable form of Cd in the soil. The Cd concentration in studied plants increased with the doses of this metal in soil but to different extents for various plant species and various plant parts. The highest Cd enrichment ratios (ER) were found for wheat and corn leaves (2 to 3), whereas, the lowest ERs were detected for corn and rye grains (0.05 to 0.2) grown at the treated soils. All samples of the control plants had ER below 1. A close relationship was found between Cd content of plants and the exchangeable form of Cd in soil, which indicates that this form of the element is readily available for plants. The proposed maximum permissible level of Cd (5 g g^–1 of added metal plus native Cd content of soils) in light soils proved to be too high for cereal plants. The threshold concentration for light soil should not exceed 3 g g^–1.     

Effect of solid-phase speciation on metal mobility and phytoavailability in sludge-amended soil

Sequential extraction was utilized for partitioning Cd, Cr, Ni, and Zn, in soil and sludge samples into five operationally-defined fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and residual. The highest amounts of Cd, Ni, and Zn, expressed as per cent of the total, were found in the Fe-Mn oxide fraction of the sewage sludge. Chromium was significantly associated with the organic fraction of the sludge. The residue was the most abundant fraction for all metals studied in the untreated soil, and for Cd and Ni in the sludge-treated soil. The concentration of exchangeable Cd and Cr was relatively low in the untreated soil and did not change much after sludge application, whereas the concentrations of exchangeable Zn increased about 50 times and the concentrations of exchangeable Ni doubled in the sludge-treated soil. The lysimetric experiment revealed an increase in Zn and Ni uptake by ryegrass and in the percentage of metals leached from the soil profile after massive sludge application. In contrast only negligible changes were observed for Cd and Cr. The assumption that mobility and biological availability are related to metal speciation was confirmed by the agreement between the distribution pattern of Cd, Cr, Ni and Zn in the soils, the uptake of the metals by plants and their capacity for leaching out from the soils.     

草酸活化磷矿粉对矿区污染土壤中Cd的钝化效果

通过盆栽莴苣试验,研究施加草酸活化磷矿粉对矿区农田土壤Cd污染钝化修复的效果。结果表明：施加南漳磷矿粉后,供试土壤交换态Cd的含量比对照降低了12.5%～20.3%;施加不同浓度经草酸活化过的南漳磷矿粉后,交换态Cd的含量与对照相比最高降低了39.5%。施加保康磷矿粉后,随着施加量的增加,与对照相比,交换态Cd的含量变化不显著;施加经草酸活化保康磷矿粉,土壤交换态Cd含量比对照最高降低了21.5%。同时,与对照相比,施加南漳磷矿粉后,残渣态Cd含量最大值是对照的2.03倍,施加经草酸活化的南漳磷矿粉后,残渣态Cd含量最大值是对照的2.61倍;施加保康磷矿粉和活化磷矿粉后,残渣态Cd含量与对照也有显著增加。施加磷矿粉和活化磷矿粉可以显著降低莴苣各部分对Cd的吸收,减少Cd在莴苣植株的累积。在施加两种活化磷矿粉后,与对照相比,莴苣地上部分Cd含量分别最多可降低41.4%、59.3%,根部Cd含量最多降低47.7%、55.1%。因此,低品位磷矿粉经草酸活化后施于Cd污染土壤,可以更好地钝化固定土壤中的Cd。     

生物炭与沸石混施对不同污染土壤镉形态转化的影响

采用室内培养模拟了低(1.0 mg/kg)、高(10 mg/kg)镉污染的土壤,通过向镉污染土壤中添加0.4%,2%,10%的1∶1的生物炭和沸石的混合物,探究了生物炭及沸石混施对不同程度镉污染土壤的pH和镉形态变化的影响。结果表明:2种不同程度镉污染土壤的pH均较CK有所提高,且随钝化剂用量的增加而增大。随着培养时间的延长,低污染土壤pH呈现降低趋势,而高污染土壤pH先升高后降低最后趋于稳定。培养后期,低污染和高污染土壤在混合物添加量分别为2%和10%时有效态镉降低比例最大,降低比例分别为56.78%和27.33%。各处理土壤随生物炭和沸石混合物添加量的增加交换态镉降低比例逐渐增大,培养后期,低污染土壤的交换态镉较CK分别降低8.35%,13.81%,20.65%,高污染土壤的交换态镉较CK分别降低10.02%,22.34%,33.01%。各处理的钝化剂能够明显的降低交换态镉的含量,增加碳酸盐结合态、铁锰氧化物结合态、有机结合态和残渣态镉的含量,低污染土壤的有机结合态明显高于高污染土壤。由此可见,生物炭与沸石混施能够降低土壤重金属的生物有效性,为农田土壤修复奠定了理论基础。     

污染水稻土中重金属的形态分布及其影响因素

通过BCR3步提取法研究了江西省贵溪铜冶炼厂污染区水稻土中重金属的形态分布。研究表明,废渣场渗滤液污染区域(渣场区)的污染较污水灌溉污染区(污灌区)严重,渣场区土壤中Cu、Pb、Cd的含量高于污灌区,而污灌区土壤Ni含量较高。在表层(0～20cm)水稻土中,Cu以可氧化态为主,Pb以可还原态和可氧化态为主,Cd以酸溶态为主,Ni以残渣态为主,不同重金属元素的有效态所占总量百分比大小顺序是Cd>Cu>Pb>Ni。土壤重金属不同形态之间也呈现一定的相关性,说明Cu与Pb、Cd、Ni之间具有同源性。土壤pH主要影响了污灌区中Cu的形态分布,以及渣场区土壤酸溶态Ni的分布。土壤有机质含量对各重金属形态分布的影响不明显。     

添加碳酸钙对土壤中镉形态转化与玉米叶片镉组分的影响

采用土壤培养、盆栽试验及连续提取测定等方法研究添加碳酸钙对外源镉在棕壤中的转化与玉米叶片镉组分的影响。与不加碳酸钙处理比较，添加碳酸钙处理土壤交换态镉含量显著下降，专性吸附态镉、铁锰氧化物结合态镉和残余态镉含量显著增加；添加碳酸钙处理可显著增加土壤ｐＨ、土壤饱和浸提液［Ｃａ２十］及［Ｃａ２十］／［Ｃｄ２十］，并显著降低饱和浸提液［Ｃｄ２＋］碳酸钙处理玉米根、茎、叶干重和全钙量显著增加，全镉含量及叶片Ｈ２Ｏ提取镉、２ｍｏｌ　Ｌ－１　ＮａＮＯ３提取镉、１０％ＨＯＡｃ提取镉、２ｍｏｌ　Ｌ－１　ＨＣＩ提取镉和残余镉含量均明显减少。上述结果显示，添加碳酸钙可降低土壤─植物体系的镉毒害。