聚丙烯酸钠为结合相的梯度扩散薄膜技术预测甘蔗田土壤中镉的生物有效性

DGT技术一直以固态结合相原位采集和测量水体、土壤或沉积物中有效态重金属,液态结合相的DGT主要应用于现场水体中金属离子的检测.本研究分别采用固态结合相梯度扩散薄膜(chelex100-DGT)装置和改进的液态结合相梯度薄膜扩散(CDM-PAAS-DGT)装置,对广西甘蔗田土壤中有效态Cd进行了测定.结果表明,2种装置提取的土壤有效态Cd含量与甘蔗(根、茎、叶)体内Cd含量都呈极显著正相关,改进的CDM-PAAS-DGT装置对土壤中有效态Cd的提取能力更强;融合土壤pH、阳离子交换量(CEC)、有机质(OM%)和土壤颗粒组成等理化指标影响,运用多元统计分析,提取出2种主成分因子,建立了多元回归模型.液态结合相DGT技术能较好地预测甘蔗田土壤中Cd的生物有效性,拓展了其应用范围.

Predicting the Cadmium Bioavailability in the Soil of Sugarcane Field Based on the Diffusive Gradients in Thin Films with Binding Phase of Sodium Polyacrylate

The diffusive gradients in thin films(DGT) technique with solid-state binding phases has been widely used for in situ collection and measurement of available heavy metals in waters, soils or sediments, whereas DGT with liquid binding phase is primarily used in the in situ analysis of heavy metals in waters. In this paper, rhizosphere soils of sugarcane were collected in Guangxi and the concentrations of cadmium (Cd) were determined by DGT with a solid-state binding phase of chelex100 (chelex100-DGT) and modified DGT with a liquid binding phase of sodium polyacrylate (CDM-PAAS-DGT). The result showed that the Cd contents in soils measured by DGT with both binding phases and Cd in the roots, leaves and unpolished stems of sugarcane had significant positive correlation. The extraction ability of the CDM-PAAAS-DGT was much higher than that of the chelex100-DGT. In addition, multivariate analyses were used to assess the impact of pH, cation exchange capacity (CEC), soil organic matter (OM) and texture. Two principal components were extracted and the linear regression models were established. The Cd bioavailability in soils could be accurately predicted by the CDM-PAAAS-DGT technique, which expanded its applicable area.