地质高背景区土壤-玉米重金属综合质量评价

为了研究地质高背景区土壤及农产品的污染程度及原因，为农产品安全生产及土壤重金属风险管控提供依据，在重庆市巫山县抱龙镇耕地区采集了土壤-玉米协同样品36套，分析了土壤-玉米中重金属(Cd、 Hg、 Pb、 As和Cr)含量及土壤pH,利用内梅罗综合污染指数法(P_N)和综合质量影响指数(IICQ)对土壤-玉米中重金属的污染程度进行了评价，并分析了土壤重金属来源及玉米重金属超标的影响因素.结果表明，研究区土壤重金属含量的平均值高于全国及重庆土壤背景值，土壤重金属富集效应明显.Cd是土壤-玉米超标的主要因子，土壤和玉米Cd的总体超标率分别为91.67%和30.55%.内梅罗综合污染指数评价结果显示，土壤以重度污染为主，占比63.89%,玉米轻度污染、中度污染和重度污染的占比分别为5.56%、 11.11%和11.11%.土壤-玉米综合质量影响指数以中度和重度污染为主，分别占比44.44%和47.22%.从重金属污染空间分布来看，玉米与土壤污染区域不一致.土壤重金属污染主要受到二叠系和三叠系地层的影响，与黑色岩系和灰岩区次生富集作用有关.玉米Cd含量主要受到土壤pH的影响，...

Comprehensive Quality Assessment of Soil-Maize Heavy Metals in High Geological Background Area

The aim of this study was to analyze the pollution degree and causes of soil and agricultural products in high geological background areas and to provide a basis for the safe production of agricultural products and the risk control of soil heavy metals. A total of 36 sets of soil-corn collaborative samples were collected in the farming area of Baolong Town, Wushan County, Chongqing City; the contents of heavy metals (Cd, Hg, Pb, As, and Cr) and soil pH in the soil-maize were analyzed, the pollution degree of heavy metals in the soil-maize was evaluated using the Nemerow comprehensive pollution index method (P_N) and comprehensive quality impact index (IICQ). The sources of heavy metals in the soil and the influencing factors of heavy metal excess in corn were also analyzed. The results showed that the average value of soil heavy metal content in the study area was higher than the national and Chongqing soil background values, and the soil heavy metal enrichment effect was obvious. Cd was the main factor of soil-maize exceeding the standard, and the overall exceeding rates of soil and corn Cd were 91.67% and 30.55%, respectively. The evaluation results of the Nemerow comprehensive pollution index showed that the soil was dominated by heavy pollution, accounting for 63.89%. The soil-maize comprehensive quality impact index was dominated by moderate and severe pollution, accounting for 44.44% and 47.22%, respectively. From the perspective of the spatial distribution of heavy metal pollution, corn and soil pollution areas were inconsistent. Soil heavy metal pollution was mainly affected by the Permian and Triassic strata and was related to the secondary enrichment of black rock series and limestone areas. The Cd content of maize was mainly affected by soil pH, and maize was relatively safe under alkaline conditions. It is suggested that the soil in the study area should be divided into risk zones according to the stratum distribution, and the planting structure should be adjusted in the high-risk areas. For the low- and medium-risk areas, it is recommended to strengthen the monitoring of agricultural inputs and reduce the input of heavy metals in the soil. Additionally, we recommend carrying out agronomic regulation in acidic soil areas to improve soil acidification, plant corn varieties with low accumulation of heavy metals, and reduce the risk of agricultural products exceeding the standard.