湖南典型酸性镉污染稻田全过程管控技术案例研究

Whole-process Control Technology of Typical Rice Field Polluted with Cadmium in Hunan:A Case Study

长沙县试验稻田属于南方典型的酸性镉污染稻田,水稻对土壤中镉的富集程度较高,镉大米的生产将对食品安全和人类健康产生风险。笔者对选取的镉污染稻田其进行了污染特征分析及污染风险评价,然后根据分析评价结果采用全过程管控模式(前端灌溉水净化,中端稳定化控制,末端植物富集)开展了修复治理研究。结果表明:该试验稻田案例地属于高风险,采用全过程管控模式后,稻米镉下降67.24%;土壤有效态镉下降38.10%,水稻增产8.85%。土壤总镉的去除率达3.17%~8.45%,油菜植株对土壤总镉的富集系数为2.69~3.43。通过估算,本案例地直接治理成本为每季5100元/hm2。本研究对污染稻田修复建立起一套完整的全过程管控集成技术并进行推广及示范有重要意义。

The tested rice field in Changsha County is typically acidic Cd-polluted paddy field,and rice has high accumulation of Cd from the soil.Cadmium rice can bring risk to food safety and human health.In this paper,the characteristics of the selected Cd-polluted paddy field were analyzed and the risk of pollution was evaluated.Then,according to the analysis and evaluation results,the restoration and treatment research was carried out,which used the whole-process control mode(the front-end irrigation water purification,the midend stabilization control and the tail-end plant enrichment).The results showed that the experimental rice field was a high-risk field,and the Cd in rice decreased by 67.24%after the application of whole-process control mode.Available Cd in soil decreased by 38.10%and the yield of rice increased by 8.85%.The removal rate of total Cd was 3.17%-8.45%in soil,and the bio-concentration factor(BCF)of Cd in rape plant was 2.69-3.43.By estimation,the direct remediation cost of this case was 5100 yuan/hm2.This study is of certain significance for establishing a complete set of whole-process control integration technology for the remediation of contaminated rice field and its promotion and demonstration.