土壤镉污染对不同品种杨树生长状况的影响

采用室外盆栽方法,以生长于辽宁省的5种不同杨树品种(分别为辽育1号、938-18、盖杨、辽育3号、小胡杨)为研究对象,通过研究不同杨树品种在土壤Cd胁迫条件下速生杨树品种对重金属Cd的反应,为Cd污染土壤的树木修复提供依据,并借以推动我国污染土壤树木修复工作的开展.研究结果表明,每一树种各处理之间的苗高、地径并没有显著差异.938-18、盖杨及小胡杨的生物量无显著差异,辽育系列苗木的生物量明显受镉污染的影响,低浓度的Cd污染刺激了苗木生长,高浓度的Cd污染对苗木造成了一定程度的伤害,抑制了苗木的生长.土壤中的Cd污染没有对938-18与小胡杨插穗生根数量造成影响.土壤中的Cd2 在一定程度上刺激了盖杨及辽育3号的生根数量.     

大冶市农田土壤中镉的空间分布特征及污染评价

矿山开采和冶炼是造成土壤重金属Cd污染的主要原因,了解典型区域土壤中Cd的空间分布特征及其污染现状,可为区域土壤污染防治与安全利用提供重要信息。本研究针对湖北省大冶市所有农田采集92个表层土壤样品和3个土壤剖面,利用GIS方法对土壤重金属Cd空间分布特征及污染状况进行了研究。结果表明大冶市土壤中Cd的含量范围为0.6 ~ 4.6 mg/kg,平均值为1.41 mg/kg,Cd迁移深度可达 40 cm。区域内土壤Cd污染范围较广,空间变异较大,还地桥镇、罗桥街办、陈贵镇等地农田土壤Cd含量较高。地积累指数评价结果显示大冶市大部分农田土壤为轻度、中度污染程度,在合理调整种植结构等方式下仍可保障农田安全利用。     

Cd、Pb单一及复合污染下土壤酶生态抑制效应及生态修复基准研究

由于土壤酶活性可有效地反映土壤重金属的污染程度,因此,本文通过研究Cd、Pb单一及复合污染对土壤酶（脱氢酶、磷酸酶、脲酶、过氧化氢酶、淀粉酶和蔗糖酶）活性的影响,以期选取合适的土壤酶指标作为Cd、Pb污染的生物标记物,为建立Cd、Pb污染生态修复的基准提供科学依据。研究结果表明,不同的土壤酶活性对Cd、Pb的敏感性各不相同,并且酶活性随土壤重金属浓度增加表现为叠加效应或拮抗效应。Cd、Pb单一及复合污染对脲酶活性抑制作用显著,Cd、Pb复合污染对脲酶活性表现为叠加效应,因此,脲酶可作为土壤Cd、Pb污染的生物标记物。通过半数生态剂量模型研究发现：Cd、Pb污染下,50%脲酶活性受抑制的毒性阈值分别为2273和2703;Cd污染土壤的生态修复基准值为1.33mg·kg-1,Pb污染土壤的生态修复基准值为106mg·kg-1。     

设施黄瓜菜田土壤镉污染预测模型及阈值研究

为指导设施栽培的安全生产,以设施黄瓜为研究对象,通过连续2年镉(Cd)污染微区试验,对设施黄瓜菜田土壤Cd污染预测模型及阈值开展研究。结果表明,设施黄瓜土壤全量Cd和有效态Cd含量均与黄瓜Cd含量呈极显著的线性、对数、幂函数和指数关系,其中,全量Cd含量以指数预测模型的相关系数最高,有效态Cd含量以线性预测模型的相关系数最高。依据国家食品卫生标准,利用呈极显著相关的模型,提出了基于土壤pH≥7.5且质地为壤土的设施黄瓜土壤全量Cd和有效态Cd的风险阈值分别为2.13mg·kg–1和0.26mg·kg–1。利用土壤敏感性指标脲酶活性对该阈值进行验证,结果表明土壤全量Cd污染达2.74 mg·kg–1时才会引起土壤脲酶活性显著下降,而≤2.13 mg·kg–1的土壤全量Cd含量并未对土壤脲酶产生明显影响。可见,通过土壤脲酶指标验证后确定的阈值是可行的;并推荐当土壤中全量Cd0.8 mg·kg–1且Cd≤2.13 mg·kg–1(pH≥7.5)时,选择黄瓜替代其他风险作物能够满足食用农产品质量的安全要求。该研究结果可为我国北方土壤Cd污染地区设施黄瓜的安全生产提供科学理论依据。     

硅酸盐土壤调理剂对蔬菜Cd污染的治理效果

通过田间试验研究了硅酸盐土壤调理剂对4种蔬菜重金属Cd污染的治理效果。结果表明,硅酸盐土壤调理剂能有效提高土壤pH值,显著降低土壤Cd活性及蔬菜对Cd的积累量,治理效果相对较好,是防治蔬菜重金属Cd污染的优选土壤调理剂,硅酸盐施用量以9 000 kg/hm~2为宜。     

纳米羟基磷灰石对重金属污染土壤Cu/Cd形态分布及土壤酶活性影响

通过室内培养实验,研究了纳米羟基磷灰石对重金属污染土壤Cu/Cd形态分布及土壤酶活性的影响。结果表明,施加纳米羟基磷灰石显著提高了土壤pH,其中3%和5%添加剂量处理60 d后使土壤pH分别提高了1.23个和1.35个单位;纳米羟基磷灰石显著减少了毒性较强的离子交换态Cu/Cd的含量,增加了毒性中等的碳酸盐结合态、铁锰氧化物结合态、有机结合态及毒性最低的残留态Cu/Cd含量,使Cu/Cd由植物可利用态向潜在可利用态转变;纳米羟基磷灰石不同程度地提高了土壤过氧化氢酶、脲酶和酸性磷酸酶活性。3种酶活性与Cu/Cd形态分布的相关性表明,过氧化氢酶和酸性磷酸酶对土壤重金属Cu/Cd活性变化比较敏感,可以作为重金属Cu/Cd污染土壤的评价指标。     

葫芦岛市连山区、龙港区土壤重金属空间分布及污染评价

本文利用地理信息系统及地统计学,对葫芦岛市连山区和龙港区土壤中重金属的污染状况进行了空间变异性分析,对Cd、Cu、Zn污染进行单因子评价。结果表明:土壤Cd、Cu、Zn的理论模型均为球状模型。Cu的C0/(C0+C)为26%,说明Cu体现为中等的空间相关性,Cd、Zn的C0/(C0+C)分别为0.3%、3.2%,说明这2种重金属体现为强烈的空间相关性。在已有监测数据的基础上,制作了该地区土壤Cd、Cu、Zn污染的预测表面,得到研究区土壤重金属的分布图及污染分布图。研究表明,龙港区和杨杖子矿区的土壤已达到了重度污染的水平,不再适合于农业生产。     

巨大芽孢杆菌LY02对黑麦草修复重金属污染土壤的影响

采用盆栽试验方法,研究了接种巨大芽孢杆菌LY02对黑麦草修复Cd、Cu污染土壤以及二者复合污染土壤效果的影响。结果表明:在Cd、Cu污染土壤及复合污染土壤中接种巨大芽孢杆菌LY02,可显著提高黑麦草地上部生物量,增幅达65.0%~108.3%;促进了黑麦草在3种污染土壤中对重金属的吸收,其中对Cd污染土壤中黑麦草吸收Cd的影响最为显著,地上部Cd吸收量较对照组增加了45.8%(P0.05);3种污染土壤中黑麦草根际土壤有效磷含量显著升高,较对照组分别增加了18.2%,26.7%,16.2%;黑麦草根际土壤中有效态Fe含量显著提高,Cu单一污染土壤中增幅最大,达到152.5%;3种污染土壤中有效态重金属含量升高,在Cu污染土壤中,有效态Cu增幅达到49.7%(P0.05)。综上所述,巨大芽孢杆菌LY02通过增加污染土壤中生物可利用态P和Fe,促进黑麦草生长;通过提高有效态Cd和Cu的含量,增加黑麦草对其吸收,从而提高了黑麦草对Cu、Cd污染土壤的修复效率。     

基于稻米摄入风险的稻田土壤镉临界值研究:个案研究

研究了浙江富阳某乡土壤Cd的污染,以及水稻对土壤Cd的吸收,并应用基于稻米摄入风险的方法推导了土壤Cd的临界值。结果表明,研究区土壤与稻米Cd污染严重。结合土壤总Cd和土壤pH应用多元回归分析建立了稻米Cd含量的预测模型。应用预测模型计算表明,pH分别为5、6、7、8时土壤Cd的临界值分别为0.42mgkg-1、0.79mgkg-1、1.49mgkg-1和2.81mgkg-1。土壤性质差异使得Cd的临界值具有较大的空间变异。在研究区,有73%地区总Cd含量超过了所对应的临界值,因此需要实施合理的风险管理措施。土壤Cd的临界值推导过程中不确定性来源主要为风险评估模型以及水稻Cd的预测模型,土壤pH是最敏感的参数。     

滇东南农田土壤重金属分布特征及污染风险评价

为了解滇东南农田土壤重金属污染及其环境风险状况,测定分析了该区域农田土壤8种重金属含量,并使用相关统计方法对其重金属进行了来源解析及污染评价。结果表明,研究区土壤Cd、Zn、Ni、Cr和Hg的平均含量均超过了云南省土壤重金属背景值,其中Cd的点位超标率最高、达77.78%。As、Hg主要来源于人类活动,Cu、Zn来源可能受自然和人为叠加影响,Pb、Cd主要来源于工业活动。污染评价结果表明,6.5

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生物炭对红壤和褐土中镉形态的影响

【目的】重金属对环境危害的大小主要取决于其形态分布,尤其是生物有效态镉 (Cd) 的含量和存在比例。添加生物炭可以降低Cd超标土壤中生物有效态Cd的含量,本文研究了施用生物炭后红壤和褐土中Cd形态的变化及其与生物炭施用量的关系,以加深对生物炭修复Cd污染土壤机理的认识。【方法】选择红壤 (pH 5.21) 和褐土 (pH 7.75) 两类土壤进行了室内培养试验。将两个过2 mm筛的自然风干土壤各40 kg,分别装于20 L塑料盒中,加Cd(NO₃)₂溶液使土壤外源Cd含量达到5 mg/kg,保持70%田间最大持水量,于25℃条件下平衡两周;之后,在每1000 g土内,分别添加生物炭0、5、10、20 g,均匀混合后,室温培养50 d;在培养1、4、7、14、21、35、49 d时分别取样,测定土壤pH和有机碳含量,利用Tessier分级法测定土壤Cd形态。【结果】红壤pH随生物炭施用量的增加显著升高,培养14天后,生物炭施加量为2%时,土壤由酸性变为弱碱性,生物炭对褐土pH的提高作用不显著。红壤和褐土有机碳含量均随生物炭施用量的增加而升高。培养49天后,红壤可交换态Cd含量的降幅较大,降幅为0.31～0.82 mg/kg,且处理2%的可交换态Cd含量最低,为1.24 mg/kg,生物炭施用量2%的红壤碳酸盐结合态Cd含量最高,为1.06 mg/kg,施用生物炭的红壤碳酸盐结合态Cd和Fe、Mn氧化物结合态Cd所占比例增加了3.14%～14.21%、8.20%～23.96%,施用生物炭的褐土碳酸盐结合态Cd和Fe、Mn氧化物结合态Cd升高了0.94%～2.61%、0.80%～7.90%。褐土的土壤有机碳含量和生物炭施用量与土壤可交换态Cd呈极显著负相关关系,与土壤碳酸盐结合态Cd,土壤Fe、Mn氧化物结合态Cd和土壤有机结合态Cd呈极显著正相关关系;红壤pH、有机碳含量和生物炭施用量均与土壤可交换态Cd呈极显著负相关关系,与土壤其他四种形态Cd呈极显著正相关关系。但在红壤中土壤有机碳和生物炭施用量与各形态Cd的相关系数均大于在褐土中的相关系数。【结论】综合分析两种类型土壤中Cd形态的变化,发现生物炭对红壤的修复效果优于对褐土的修复效果,因此生物炭可以作为Cd污染的酸性土壤的一种修复改良材料。     

Spatial patterns of cadmium contents related to soil heterogeneity

To investigate Cd behavior in a heterogeneous soil, soil samples were taken along a transect in a field. Total Cd content, Cd concentration in solution, and soil properties controlling Cd sorption were measured. The scale and degree of variability of these parameters were assessed using statistical and spectral analysis. No substantial correlation was found between total Cd and Cd in solution. However, with a scaled sorption model that accounts for effects of pH and organic matter content the variability of total Cd was predicted well as a function of measured concentrations and soil properties. Apparently, total Cd contents of this soil are primarily controlled by the organic matter content and pH.     

Cadmium fractions in an acid sandy soil and Cd in soil solution as affected by plant growth

In a previous experiment, plants were able to immobilize or solubilize Cadmium (Cd) in a sandy acid soil enriched with 40 μmol Cd kg^–1, because Cd solution concentration was decreased by maize (Zea mays) and sunflower (Helianthus annuus), and increased by flax (Linum usitatissimum L. ssp. usitatissimum) and spinach (Spinacia oleracea). It is assumed that the equilibrium with Cd fractions in the soil solid phase and the chemical form of Cd in the soil solution were affected. In the present study, the effect of the four plant species mentioned above on Cd binding in soil was investigated by means of a fractionation of soil Cd with a sequential extraction of seven steps. The seven fractions of Cd are operationally defined by the extraction sequence that follows the order of increasing acidity with extractants of different complexing and redox properties. In the unplanted soil, Cd was predominantly present in the exchangeable Fraction I (F. I) and easily mobilizable Fraction II (F. II) (64%). Significant concentrations of Cd were found in F. III (occluded in Mn oxides; 22%) and F. IV (organically bound; 10%). Fractions V (occluded in poorly crystalline Fe oxides), F. VI (occluded in well crystallized Fe oxides), and F. VII (residual fraction) amounted to less than 5% of the total soil Cd concentration. The plants changed the binding of Cd in soil in a different manner. All plants decreased F. I, but F. II was increased by maize and spinach, decreased by flax or remained unaffected by sunflower. Fraction III was not affected by maize and flax, but decreased by sunflower and spinach, and F. IV was not affected by sunflower and spinach, but was increased by maize and flax. These changes of Cd fractions were not related to the changes the plants had caused in total Cd or Cd²⁺ concentration of the soil solution. These results show that plant species differ in how they affect Cd binding to the soil solid phase, but this effect is not related to how they affect Cd in soil solution. The mechanisms by which plants affect the relationship between the soil solid and liquid phase are still unclear.     

基于RBF神经网络的土壤重金属空间变异研究

本文采用径向基函数神经网络(Radial Basis Function Neural Network,RBFNN)预测太原市晋源区表层土壤中重金属Cr、Cd、Hg的空间变异,并与普通克里格(Ordinary Kriging)插值结果进行对比分析,以选择更合适的土壤重金属空间插值方法。研究结果表明:1)在拟合RBFNN模型过程中,选择合适的spread散布常数可以使模型达到最优,研究区域土壤Cr的最优散布常数为0.08,Cd的最优散布常数为0.10,Hg的最优散布常数为0.14,这组散布常数对于局部区域农田土壤重金属插值模拟有一定的参考意义。2)RBFNN方法与Ordinary Kriging方法对区域重金属浓度分布的预测趋势一致,土壤Cd含量在区域中部较高,尤其是从东北方向到西南方向的轴线上较高,向两侧形成扩散递减趋势;土壤中Cr含量总体分布趋势也是中部较高,其他区域相对较低;土壤Hg含量在区域东北部较高,由东北方向到西南方向浓度逐渐递减。且土壤重金属在区域中的分布与当地的污染源分布相对应。在样本数有限的情况下对土壤重金属进行空间变异研究时,RBFNN方法比Ordinary Kriging方法的预测精度更高更有效。     

典型潮土剖面主要性质和微量金属垂直分布特征

对不同利用方式下石灰性潮土剖面主要性质和微量金属元素含量垂直分异规律进行了初步研究。结果表明,长期耕种的菜地和旱地0～15cm表层土壤有机碳含量高于其他土层,pH和CaCO3含量低于下层土壤;表层土壤Cd已明显积累;但Cd、Pb、Cu、Zn含量均未超过国家土壤环境质量二级标准。几种微量金属全量在菜地和旱地表层土壤之间没有显著差异,但菜地表层土壤DTPA可提取态Cd含量显著高于旱地。从微量金属的剖面分布看,石灰性潮土全量Cd和DTPA可提取态Cd、Pb、Cu、Zn均有明显的表聚现象,这种分布与土壤有机碳含量、pH和CaCO3含量显著相关。聚类分析表明,该区域耕作土壤环境分析样品的采集以表层土壤0～15cm多点混合样品为宜。     

Effect of soil application of cadmium contaminated lime on soil cadmium distribution and cadmium concentration in strawberry leaves and fruit

Heavy metal environmental pollution which occurs as a result of lime contaminated with cadmium (Cd) poses a potential health hazard. This investigation was undertaken to study uptake of Cd by strawberry plants grown in soil amended with three different sources and two different rates of industry waste lime containing 3.4, 14.3, and 60.0 mg Cd/kg, respectively. The effects of Cd applied to the soil were investigated, including its distribution in the soil and effect on Cd concentration in strawberry cv. Senga Sengana (Fragaria anassa) leaves and fruit in response to soil organic matter content and lime rates. Cadmium accumulated mainly in the plough layer, increasing from 0.170 mg Cd/kg (background level) to a maximum of 1.2 mg Cd/kg. Fruit had very high, hazardous Cd concentrations regardless of its content in the soil. This indicates that Cd was easily taken up by strawberry plants and accumulated in upper plant parts, including the fruit. Soil Cd content had no effect on concentration of this element in strawberry fruit. However, plant Cd uptake and fruit concentration was increased in acid soils even when soil Cd concentration was low.     

根瘤菌存在下土壤胶体和矿物对镉的吸附

Experiments were conducted to study the adsorption of Cd on two soil collids(red soil and yellowbrown soil) and three variable-charge minerals (goethite,noncrystalline Fe oxide and kaolin) in the absence and presence of rhizobia.The tested strain Rhizobium fredii C6,tolerant to 0.8 mmol L^-1 Cd,was selected from 30 rhizobial strains.Results showed that the isotherms for the adsorption of Cd by examined soil colloids and minerals in the presence of rhizobia could be described by Langmuir equation.Within the range of the numbers of rhizobial cells studied,the amount of Cd adsorbed by each system increased with increasing rhizobial cells,Greater increases for the adsorption of Cd were found in red soil and kaolin systems.Rhizobia influence on the adsorption of Cd by examined soil colloids and minerals was different from that on the adsorption of Cu.The presence of rhizobia increased the adsorption affinity of soil colloids and minerals for Cd,particularly for the goethite and kaolin systems.The discrepancies in the influence of rhizobia on the adsorbability and affinity of selected soil colloids and minerals for Cd suggesed the different interactions of rhizobia with various soil components.It is assumed that bacterial biomass plays an important role in controlling the mobility and bioavailability of Cd in soils with kaolinite and goethite as the major colloidal compnents,such as in variable-charge soil.     

沿海滩涂区土壤重金属含量分布及其有效态影响因素

为揭示沿海地区土壤重金属含量的空间分布特征及其与自然、人为因素的关联,以近年来围垦开发强度较大的江苏沿海某滩涂区为研究对象,采用经典统计与地统计相结合的方法研究了表层土壤主要重金属Pb、Cr、Cd、As全量与有效态含量状况及其空间分布,分析了沿海滩涂区土地利用方式对重金属含量的影响,探讨了重金属有效态含量与土壤理化性质的相关性。结果表明:目前研究区土壤环境质量状况良好,土壤Pb、Cr、Cd、As均呈累积趋势但基本都低于土壤环境质量一级标准值;土地利用方式不同程度地影响了Pb、Cr、Cd全量与有效态含量,As全量与有效态含量受土地利用方式影响较小;研究区土壤Pb、Cr、Cd全量与Pb、Cr有效态含量具有明显的趋势效应,且研究区土壤重金属全量与有效态含量的空间分布受大尺度的潮汐作用与小尺度的人为因素的共同控制;土壤Pb、Cr、Cd有效态含量与黏粒含量、阳离子交换量和p H显著负相关,与有机质呈显著正相关,土壤As有效态含量仅与土壤p H显著正相关。本研究为沿海滩涂区土壤重金属源头减量、活性钝化、污染消减与风险防范提供科学依据。     

稻壳基生物炭对生菜Cd吸收及土壤养分的影响

探讨稻壳基生物炭对Cd污染土壤上叶菜吸收Cd和土壤Cd形态的影响作用,明确稻壳基生物炭对土壤Cd污染的调控效应,可为合理利用稻壳基生物炭降低叶菜Cd含量提供参考。采用盆栽试验,研究了稻壳基生物炭在不同用量水平下对2茬生菜地上部Cd含量、土壤养分含量及Cd赋存形态的影响。结果表明,在5~25 g-kg-1用量范围内,稻壳基生物炭显著降低了2茬生菜地上部和根系Cd含量,且在最大用量25 g-kg-1时效果最好,地上部Cd含量分别比未施稻壳基生物炭的对照处理降低了19.6%和45.8%,根系Cd含量分别降低了36.8%和28.0%。在25 g-kg-1用量水平下,稻壳基生物炭对土壤p H、有效磷、速效钾及有机质含量提升效果明显,但显著降低了土壤碱解氮含量。施加稻壳基生物炭对土壤有效态Cd含量及Cd化学形态也有不同影响。随着稻壳基生物炭用量的增加,土壤NH4OAc提取态Cd含量和弱酸提取态Cd含量显著降低,在用量为25 g-kg-1时,分别比对照降低17.9%和10.4%,可还原态Cd含量无显著变化,可氧化态Cd含量呈减低趋势,残渣态Cd含量增加17.6%。因此推测,提升土壤p H、降低土壤有效态Cd含量、增加残渣态Cd含量可能是稻壳基生物炭降低生菜体内Cd含量的主要原因。稻壳基生物炭可以作为土壤改良剂,抑制Cd污染土壤上叶菜对Cd的吸收,改善土壤养分状况。     

Effect of microorganisms on extractability of Cd from soil with NaOH and DTPA

Because Cd is extremely toxic, an understanding of the factors that allow or prevent Cd entrance into the food chain is important. The fate of Cd in soil is strongly influenced by microbial activity. Thus, an attempt was made to develop a method for studying the effect of microorganisms on Cd sorption to soil and availability to plants. It was found that the amount of Cd extracted from soil to soil suspensions with 0.1 m NaOH is related to microbial proliferation. In addition, an increase of Cd in NaOH extracts occurred concurrently with a decrease of Cd in DTPA extracts. Our observations suggest that the binding of Cd to microorganisms or their products can immobilize Cd and consequently affect its bioavailability.