广西天峨主要耕地区农作物中重金属元素富集特征与影响因素

Enrichment Characteristics and Influencing Factors of the Heavy Metal Elements in Crops from the Primary Cultivated Areas of Tian’e County,Guangxi

重金属污染制约着农产品安全问题,本文选择广西天峨县为研究切入点,以揭示农作物中重金属元素生态风险情况。系统采集60套水稻和玉米样品以及根系土壤样品,测试Cd、Cr、Hg、As和Pb等5种重金属元素含量,采用地累积指数、生物富集系数及相关性分析等方法进行数据处理。研究结果表明:除了Hg之外,其它重金属元素Cd、Cr、As和Pb含量均未超标,属于食品安全范围;其中Cr含量最高,平均值为0.094 mg/kg,而Cd含量变异系数极大,高达103%;水稻籽实中Cd、Hg和As等重金属含量普遍高于玉米籽实。根系土壤处于酸性环境,有机质养分较丰富,并存在中等程度Cd污染情况;重金属形态绝大多数为残渣态,其中Cd离子活性较高。农作物对Cd和Hg具有较强的富集能力,碎屑岩区土壤中重金属的生物富集系数高于碳酸盐岩区。经相关性分析表明,水稻中Hg含量与根系土壤中Cd含量呈极显著正相关关系,同时土壤酸碱度及有机质是影响农作物中重金属元素含量的重要因素。因此,适当调整土壤酸性程度、合理增施有机肥料,能够有效控制重金属污染风险,这对保障农产品安全具有基础性意义。

Heavy metal pollution poses a significant challenge to the safety of agricultural product.This study focuses on Tian’e County,Guangxi,as a study entry to reveal the ecological risks associated with heavy metal contamination in crops.In this study,sixty sets of rice and corn samples and their corresponding rhizosphere soils were collected for analysis.The contents of five heavy metals,Cd,Cr,Hg,As,and Pb,were measured.Data analysis was performed using multiple approaches,including the geo-accumulation index,bioconcentration factor,and correlation analysis.The results indicate that except of Hg,levels of Cd,Cr,As and Pb fall within acceptable limits of food safety,with Cr being the most prevalent at an average concentration of 0.094 mg/kg.Notably,Cd exhibits a high variation coefficient of 103%.In general,rice seeds contain higher concentrations of Cd,Hg,and As than the corn seeds.The soil was detected to have an acidic environment with a high organic nutrient content,and shows a moderate Cd contamination.Most heavy metals in the soil were in residual forms,but Cd ions demonstrated increased activity.Moreover,the crops display a pronounced ability to accumulate Cd and Hg,and the bioconcentration factor of heavy metals in clastic rock areas was higher than in the carbonate areas.Correlation analysis demonstrates that a strong positive correlation existing between the Hg content in rice and the Cd concentration in rhizosphere soil.Additionally,the soil pH and organic content considerably influence the heavy metal levels in crops.Therefore,adjusting soil acidity appropriately and reasonably utilizing organic fertilizers can effectively mitigate heavy metal pollution risks,which was crucial for ensuring the safety of agricultural products.