工业发达区土壤和作物镉污染风险评价与生态修复研究

Risk Assessment and Ecological Restoration of Cadmium Pollution in Soil and Crops in Developed Industrial Areas

摘要:

开展工业发达区土壤和作物镉污染风险评价,可为农田生态修复和安全利用提供理论依据。 采用单因子污染指数法、改进的地累积指数法、生物富集系数和地统计学方法评价土壤和作物的镉污染,结合潜在生态风险和人体健康风险评价模型进行风险分区并制定生态修复策略。 结果表明,土壤和作物 Cd 含量均存在不同程度的超标, 土壤和水稻 Cd 的超标率分别为 38. 46% 和 46. 15% ,轻度和重度污染占比略高,水稻 Cd 的富集特征明显;空间分布上土壤和水稻 Cd 含量差异性显著,土壤 Cd 高值区主要分布在生产活动密集的城镇和工业区;生态风险属于高生态危害系数、中等生态风险等级,对成人和儿童的致癌风险较低。 研究区应根据土壤和作物的污染分级和风险分区采取差异化的生态修复措施,对安全区应采取低累积作物、钝化和水肥调控修复措施,对潜在风险区应采取超富集植物萃取与低累积作物套作、化学 / 微生物活化 / 钝化调控修复措施,对风险区应采取非食用类能源 / 经济作物种植结构调整、农业生物质高效资源化综合利用修复措施,以实现重金属污染土壤的分类生态修复与安全利用。

Abstract:

Risk assessment of cadmium pollution in soil and crops in developed industrial areas can provide theoretical basis for ecological restoration and safe utilization of farmland. Using the single-factor pollution index method, the modified geo-accumulation index method, the bioconcentration factor, and geostatistical methods, the cadmium contamination in soil and crops is evaluated. These are combined with potential ecological risk and human health risk assessment models to conduct risk zoning and formulate ecological remediation strategies. The results showed that the contents of Cd in soil and crops exceeded the standard to varying degrees. The exceedance rates of Cd in soil and rice were 38. 46% and 46. 15% , respectively. The proportion of mild and severe pollution was slightly higher, the enrichment characteristics of Cd in rice were obvious. There was a significant difference in Cd content between soil and rice in spatial distribution, and high-value of soil Cd areas were mainly distributed in urban and industrial areas with intensive production activities. Ecological risk belonged to high ecological hazard coefficient, medium ecological risk level, and had a low carcinogenic risk for adults and children. The study area adopted differentiated ecological restoration measures based on the pollution classification and risk zoning of soil and crops. For safe areas, low accumulation crops, passivation, and water fertilizer regulation restoration measures should be taken. For potential risk areas, hyper accumulation plant extraction and low accumulation crop intercropping, chemical / microbial activation / passivation regulation restoration measures should be taken. For risk areas, non-edible energy / economic crop planting structure adjustment and comprehensive utilization of agricultural biomass resources should be adopted to achieve classified ecological restoration and safe utilization of heavy metal contaminated soil.