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重金属镉(Cd)在土壤-蔬菜系统中转移方程的建立是农田Cd污染控制和风险评估的关键.本研究通过调查湖南省攸县745个土壤-蔬菜样品Cd含量,应用转移方程、敏感性分布曲线(SSD)和多元回归方法分析不同类别蔬菜Cd累积特征和影响因素,预测不同土壤条件下蔬菜Cd含量并推导相应土壤Cd风险阈值.结果表明:叶菜对Cd胁迫较根菜敏感;土壤pH、土壤总Cd和土壤有机质(SOM)是影响蔬菜Cd富集的3个主要因子;转移方程对叶菜和根菜的解释程度分别为54.2%和69.1%.土壤Cd风险阈值随土壤pH和SOM的增加而增加,根菜在严重酸化土壤区Cd累积风险较高.当前国家土壤环境质量标准对于严重酸化、有机质含量较低的土壤过于宽泛.
The establishment of the transfer equation of heavy metal cadmium in soil-vegetable system is the key to Cd pollution control and risk assessment in farmland.In this study, we investigated the Cd content of 745 soil-vegetable samples from You County, Hunan Province, and applied the transfer equation and sensitivity distribution (SSD) and multiple regression analysis were used to analyze the accumulation characteristics and influencing factors of Cd in different types of vegetables, and to predict the Cd concentration in vegetables under different soil conditions and to derive the corresponding Cd risk thresholds. The results showed that Cd stress was more sensitive to Cd than leafy vegetables, Soil total Cd and soil organic matter (SOM) were the three main factors affecting the enrichment of Cd in vegetables. The transfer equation explained 54.2% and 69.1% of leafy and root vegetables respectively. The threshold of soil Cd risk increased with soil pH and SOM However, the root vegetables had a higher risk of Cd accumulation in severely acidified soils.At present, the national soil environmental quality standards are too broad for heavily acidified soils with low organic matter content.