基于土壤标准适宜性评价与环境基准的黔西北高Cd农用地精准管理新思路

A novel approach to accurate management of agricultural land with high level Cd in northwest Guizhou——based on current soil standards suitability evaluation and study of environmental benchmark

我国现行土壤标准(GB 15618-2018)在高重金属背景值农用地评价的准确性难以满足地方政府对农用地的精准管理。以黔西北水城区高镉(Cd)农用地为例,采集了164组土壤-农产品协同监测样品,系统地探讨了现行标准对农用地评价的适应性,并基于物种敏感分布模型(SSD)反推区域农用地环境风险基准值。结果表明,研究区土壤Cd质量分数总体呈高累积特征,而农产品可食部位中Cd质量分数整体偏低。164组样品中有72组适应性分析结果为不适宜,假阴性/阳性错误比率为43.90%。推导所得的土壤风险值临界值(HC5)和警戒值(HC95)分别为:水稻0.7和20.9 mg·kg^(-1)、玉米2.4和48.5 mg·kg^(-1)、叶菜蔬菜2.5和151.2 mg·kg^(-1)。基于上述阈值重新评价研究区农用地,其适应性比率整体从56.10%提高至97.60%。本研究结果可为类似高背景值重金属农用地的精准分类和管理提供新思路。

The accuracy of China’s current soil standard(GB 15618-2018)in the evaluation of agricultural land with high heavy metal content was challenging,which was difficult to meet the accurate management of agricultural land by local government.In this study,164 pairs of soil-corn samples were collected in Shuicheng District,Northwest Guizhou.,the adaptability of current standards to agricultural land evaluation was systematically discussed,and the regional agricultural land environmental risk benchmark value was deduced by means of species sensitive distribution model(SSD).The results showed that the Cd accumulation in the soil of the study area was generally high.However,the Cd content in the edible parts of agricultural products was low as a whole.The results of adaptability analysis of 72 of 164 pairs samples were inappropriate,and the false negative/positive error rate was 43.9%.The hazardous concentration of 5%(HC5)and of 95%(HC95)of soil Cd were:0.7 and 20.9 mg·kg^(-1)for rice,2.4 and 48.5 mg·kg^(-1)for corn,2.5 and 151.2 mg·kg^(-1)for leafy vegetables,respectively.After re-evaluating the agricultural land in the study area by the deduced value,the adaptability ratio increased from 56.10%to 97.60%.Those results would provide a positive idea for the accurate classification and management of region with high heavy metals level.