基于梯度薄膜扩散技术评估黑麦草吸收Cd的研究

Assessment of cadmium bioavailability to ryegrass in soils by diffusive gradients in thin films

分别采用固态结合相(Chelex100)和液态结合相(聚丙烯酸钠,PAAS)的梯度薄膜扩散技术(DGT)对盆栽黑麦草实验中的土壤有效态Cd进行了提取,结果表明2种不同结合相的DGT技术提取的土壤有效态Cd含量与黑麦草地上部和地下部的Cd含量都呈显著相关关系,其相关系数分别为0.90,0.89(Chelex100-DGT)和0.90,0.87(PAAS-DGT).运用多元统计分析方法研究土壤pH值、阳离子交换量(CEC)、有机质(OM)和土壤颗粒组成等理化指标的影响,提取出2种主成分因子,建立逐步回归模型.第1主成分与OM和黏粒组成之间呈显著相关,定义为代表土壤中影响重金属生物有效性的"有机指标",第2主成分则土壤pH值和CEC相关程度较高,定义为代表土壤中影响重金属生物有效性的"无机指标".研究表明Chelex100-DGT和PAAS-DGT技术均能较好预测黑麦草对Cd的吸收,且包含了土壤理化性质的影响.

Cd bioavailable concentrations in the rhizosphere soils of ryegrass were measured by DGT with different binding phases（Chelex100-DGT and sodium polyacrylate（PAAS）-DGT）.Simple linear regression analyses showed significant correlation between Cd concentrations in ryegrass shoots and roots and DGT measured Cd concentrations.The correlation coefficients for plots using metals measured by Chelex100-DGT were 0.90 and 0.89,and 0.90 and 0.87 using metals measured by PAAS-DGT.Multivariate analyses were used to assess the impact of pH,cation exchanged capacity（CEC）,soil organic materials（OM） and texture.Two principal components were extracted and the linear regression models were established.The first was well correlated with OM and clay,which was defined as the representative of ＂organic matter＂.The second primarily correlated with pH and CEC,which was defined as the representative of ＂inorganic ions＂.Both Chelex100-DGT and PAAS-DGT could better predict the accumulation of Cd in ryegrass and the potential runoff of Cd from soils,and DGT measurements incorporate the mail soil properties affecting Cd bioavailability.