【作者】 丁琼；

【导师】 华珞； 马义兵；

【作者基本信息】 首都师范大学 ， 环境科学， 2012， 硕士

【摘要】 土壤-植物系统中镉转移系数是反应土壤中镉生物有效性与植物对镉富集能力的综合指标。植物对重金属的转运能力可以用转移系数(TF)来表示,是指植物体内重金属浓度与土壤中重金属浓度的比值,它与重金属的生物有效性有直接关系,受土壤理化性质以及生物种类及环境条件等各个方面因素影响。本文旨在通过对土壤理化性质对土壤-植物系统中镉转移系数的影响研究,量化土壤性质与镉转移系数之间的关系,建立土壤-植物系统镉转移模型；在此基础上,进一步研究了不同钝化剂对镉在土壤-植物系统转移的影响,可望为重金属镉污染土壤的修复、农产品镉转移系数的预测预报及镉污染土壤的的安全生产提供理论基础。本文主要包括两方面内容：1、土壤性质对土壤-植物系统镉生物有效性的影响。本部分以镉高吸收类蔬菜(菠菜和西红柿)作为供试植物,通过盆栽试验研究了不同土壤理化性质与土壤-植物系统镉转移系数的影响。供试土壤选取全国范围内具有代表性15种未被镉污染的土壤,设置三个镉污染梯度(0、1、2mg/kg),每个梯度设4个重复,共计360个样本。通过分析土壤与植物中的镉总量以及土壤性质之间的关系,发现土壤-植物系统镉转移系数主控因子是土壤pH、二硫酸盐-柠檬酸盐提取态铝(CD-A1);二硫酸盐-柠檬酸盐提取态铁(CD-Fe),其控制变异系数分别为：44.6%-61.8%,42.2%-89.8%,42.2%-90.7%。同时土壤有机质(OMC)、阳离子交换量(CEC)以及粘粒含量(<2μm, Clay)是控制土壤-植物系统镉转移的次要因子。在多因子共同控制下,可进一步提高可控变异系数。不同处理条件下土壤-菠菜系统镉转移系数最优预测方程为：对照土壤-菠菜系统镉转移系数的最优预测方程为：TF1=2.679-0.248pH-0.020CEC+0.0629CD-A1(R2=0.811,p<0.001);外源镉污染土壤-菠菜系统镉转移系数的最优预测方程为：TF1=4.888-0.404pH-0.328OMC+0.0762CD-A1(R2=0.710, p<0.001);外源镉污染土壤-菠菜系统外源镉转移系数的最优预测方程为：TF2=5.433-0.446pH-0.376OMC+0.0517CD-A1(R2=0.701,P<0.001);不同处理条件下土壤-西红柿系统镉转移系数模型为：对照土壤-西红柿系统镉转移系数的最优预测方程为：TF1=5.101-0.596pH-0.064CEC+4.341CD-Mn (R2=0.895,p<0.001);外源镉污染土壤-西红柿系统镉转移系数的最优预测方程为：TF1=0.183+0.532CD-Al-0.821OX-A1+3.700CD-Mn (R2=0.951, p<0.001);外源镉污染土壤-西红柿系统外源镉转移系数的最优预测方程为：TF2=2.459-0.301pH+12.097CD-Mn-10.613OX-Mn (R2=0.950,p<0.001).其中pH代表土壤pH值,CEC代表阳离子交换量,CD-A1代表二硫酸盐-柠檬酸盐提取态铝,OMC代表土壤有机质,CD-Mn代表二硫酸盐-柠檬酸盐提取态锰,OX-Mn代表草酸盐提取态锰。2、研究不同钝化剂对土壤-植物系统镉转移系数的影响。本部分试验以低吸收豆类蔬菜(豇豆)作为供试植物,通过田间试验研究了在轻度Cd污染石灰性土壤(Cd1.5mgkg)中施加赤泥、油菜秸秆、玉米秸秆、赤泥+油菜秸秆等钝化处理并配施硫酸锌肥料对土壤中Cd的生物有效性的影响。结果表明,与对照相比,不同钝化处理可显著(p<0.05)降低豇豆豆角中Cd浓度和土壤中可溶态Cd浓度；钝化处理条件下豇豆豆角中Cd浓度降低了27%(玉米秸秆处理)-83%(赤泥+油菜秸秆处理)。在施加钝化剂的基础上,配施硫酸锌肥料可进一步降低豇豆对Cd的吸收,各钝化处理在配施锌肥后,豇豆豆角中Cd平均浓度与未施锌肥相比降低了27%。对不同作物秸秆而言,富含巯基的油菜秸秆比富含纤维素的玉米秸秆钝化效果好。由此可见,在轻度Cd污染的石灰性土壤中,无机钝化剂赤泥和富含巯基的油菜秸秆复合使用是一种高效且环境友好的钝化手段。同时,合理施用锌肥可能会进一步降低作物对Cd的吸收。本文系统的研究了土壤基本性质及钝化剂对土壤-植物系统镉转移的影响,发现除土壤性质对镉转移系数有较大影响外,一些土壤组分对镉转移系数也有显著影响,如CD-A1和CD-Fe。在轻度镉污染土壤中添加钝化剂可以改变土壤性质及重金属的有效态含量,从而有效控制镉在土壤-植物系统中的转移,保证农产品安全,为污染土壤安全利用提供一定的理论支持。更多还原

【Abstract】 Cadmium transfer factor in soil-plant system represents the comprehensive index of cadmium bioavailability and accumulation ability of plants. Transfer factor (TF) stands for the ability of plants transfer heavy metal, which is the ratio of heavy metal concentrations in plants to that in soil. It directly relates to bioavailability of heavy metals, affecting by physical, chemical and biological factors. This study aims to find the effect of physicochemical properties of soil no cadmium transfer factor, then develop a model, that is helpful for rish assessment and remediation of cadmium contaminated soils:This study involves two parts:One is about the effect of soil properties on cadmium bioavailability in soil-plant system. The plants used were spinach and tomatoes. Uncontaminated soils (15soiis) were collected with various properties over our country. Three concentration gradients (0、1、2mg/kg) of cadmium added to soils. After analyzing the contents of Cd in plants and soils, it was shown that main control factors on TF are pH, citrate/dithionate extractable A1(CD-A1); citrate/dithionate extractable Fe (CD-Fe), they can partly control the coefficients of variation in soil-plant system with44.6%-61.8%,42.2%-89.8% and42.2%-90.7%, respectively, while OMC, CEC and clay content(<2μm, Clay) are secondary factors.The optimal prediction equation of soil-spinach system cadmium transfor factor is:Control the optimal prediction equation of the soil-spinach system cadmium transfer factor is:TF1=2.679-0.248pH-0.020CEC+0.0629CD-Al (R2=0.811,P<0.001);Added exogenous cadmium contaminated soil-spinach system Cd transfer factor of the optimal prediction equation as follows:TF1=4.888-0.404pH-0.328OMC+0.0762CD-A1(R2=0.710,p<0.001);Added exogenous cadmium contaminated soil-spinach system added exogenous cadmium transfer factor of the optimal prediction equation as follows:TF2=5.433-0.446pH-0.376OMC+0.0517CD-Al(R2=0.701,p<0.001); The optimal prediction equation of soil-tomato system cadmium transfor factor is:Control the optimal prediction equation of the soil-tomato system cadmium transfer factor is:TF,=5.101-0.596pH-0.064CEC+4.341CD-Mn (R2=0.895,p<0.001)Added exogenous cadmium contaminated soil-tomato system Cd transfer factor of the optimal prediction equation as follows:TF1=0.183+0.532CD-Al-0.821OX-A1+3.700CD-Mn(R2=0.951,p<0.001;Added exogenous cadmium contaminated soil-tomato system added exogenous cadmium transfer factor of the optimal prediction equation as follows:TF2=2.459-0.301pH+12.097CD-Mn-10.613OX-Mn (R2=0.950,p<0.001)In the above content pH is represents the value of soil pH; CEC is represents cation exchange capacity; OMC is represents soil organic matter; CD-A1is represents citrate/dithionate extractable A1; CD-Mn is represents citrate/dithionate extractable Mn; OX-Mn is represents oxalate extractable Mn.The other is about how to reduce Cd phytoavailability in calcareous soils, the effects of soil amendments of red mud, rape straw, corn straw and red mud plus rape straw in combination with zinc fertilization on Cd extractability and phytoavailability to cowpea were investigated in a calcareous soil with added Cd at1.5mg/kg. The results showed that water soluble and exchangeable Cd in soils was significantly decreased by the amendments, which resulted in significant decrease by about27%(corn straw)-83%(red mud plus rape straw) in Cd concentration in cowpea. Combined with amendments, Zn fertilization further decreased the Cd concentration in cowpea. Compared with amendments only, the concentrations of Cd in the edible parts of cowpea treated with the Zn fertilization plus amendments decreased by27%on average. Also cruciferous rape straw was more effective than gramineous corn straw. In all treatments, rape straw plus red mud combined with Zn fertilization was most effective in decreasing Cd phytoavailability to cowpea in soils, and it is potential to be an efficient, cost-effective and environmentally friendly measure to ensure food safety for crop production in mildly Cd-contaminated and calcareous soils.更多还原