基于土壤质量的改良剂修复镉污染稻田综合效果评价

A comprehensive evaluation of remediation effects on cadmium contamination in paddy fields based on soil quality

受污染农田修复技术应用效果的综合评价,在当前我国土壤污染管控与修复工作中尤为重要和紧迫。本文针对自主研发的改良剂,在我国华南地区受镉(Cd)污染的水稻种植区开展野外大田试验,重点围绕土壤环境、肥力和健康质量的变化,探索改良剂施用对土壤质量的影响;选择DTPA浸提态Cd、有机质、碱解氮、有效磷、速效钾、阳离子交换量(CEC)、糙米Cd和稻谷产量构建指标体系,利用动态加权综合评价模型评判改良剂的修复效果。结果表明,当改良剂施用量为6000 kg·hm^(-2)和7500 kg·hm^(-2)时,DTPA浸提态Cd含量分别减少10.5%和8.8%。当改良剂用量为6000 kg·hm^(-2)时,有机质含量减小6.3%;改良剂没有显著影响碱解氮、有效磷和CEC含量,但是显著提高了速效钾含量。当改良剂用量为1500 kg·hm^(-2)时,糙米Cd含量增加23.9%;当改良剂用量≥4500 kg·hm^(-2)时,糙米Cd含量显著低于国家标准,且修复效率(RE)均超过40%。当改良剂用量为4500 kg·hm^(-2)时,稻谷产量增加18.7%。采用动态加权综合评价模型研究发现,当用量为6000 kg·hm^(-2)时,改良剂修复Cd污染稻田的综合效果最佳。

At present,it is overly important and urgent to carry out a comprehensive evaluation of the effects of some current remediation technologies against cadmium(Cd)contamination in paddy fields in China,which play a key role in promoting the control and remediation of soil pollution.In this study,a self-developed amendment was selected,and a field experiment was carried out in a rice-growing region in South China to investigate the effects of the amendment application on the soil environment,fertility,and health.Additionally,DTPA extractable Cd,organic matter,alkaline hydrolytic nitrogen,available phosphorus and potassium,cation exchange capacity(CEC),brown rice Cd,and rice yield were selected to construct a comprehensive evaluation index system,which was used to comprehensively evaluate the remediation effect of the amendment application in Cd-contaminated paddy fields according to a dynamic weighted comprehensive evaluation method.The results showed that the concentrations of DTPA extractable Cd in treatments of 6000 kg·hm^(-2)and 7500 kg·hm^(-2)were reduced by 10.5%and 8.8%from the control treatment,respectively.The soil organic matter content in the 6000 kg·hm^(-2)treatment decreased by 6.3%compared with the control.Amendment application did not significantly affect alkaline hydrolytic nitrogen and available phosphorus contents and CEC but significantly increased available potassium content.Application at a rate of 1500 kg·hm^(-2)significantly increased brown rice Cd content by 23.9%.When the application rate was≥4500 kg·hm^(-2),brown rice Cd content was significantly lower than the National Food Safety Standard.Moreover,the remediation efficiency(RE)was more than 40%.The 4500 kg·hm^(-2)treatment significantly elevated the rice yield,representing an 18.7%increase from the control treatment.The dynamic weighted comprehensive evaluation method’s results showed that the comprehensive remediation effect of amendment application at a rate of 6000 kg·hm^(-2)on Cd contaminated paddy fields was optimal.