中国典型设施栽培土壤Cu、Zn累积特征及风险预测

为了探明铜(Cu)和锌(Zn)在设施栽培土壤中的累积现状及潜在风险,该研究基于中国8个省16个州市典型区域的设施栽培土壤全量和有效态含量,系统分析了Cu、Zn的累积现状及风险特征,并采用分段线性模型(Split-line Model)拟合了土壤Cu、Zn有效态累积量与种植年限的关系,预测了土壤Cu、Zn累积量超风险限量...

Accumulation characteristics and risk prediction of Cu and Zn contents in typical facility soils in China

Excessive accumulation of trace elements in the protected cultivation soil has become an important factor for the degradation of soil quality. In particular, both copper (Cu) and zinc (Zn) are micronutrient elements required for plant growth and heavy metal in the soil environment. It is highly demanding to consider the Cu, Zn cumulative risks. Therefore, this study aims to investigate the accumulation characteristics and risk prediction of Cu, Zn content in the protected cultivation soil. A total of 131 soil samples were also collected using 5-point sampling in the typical regions of 16 cities in 7 provinces and 1 autonomous region (including Liaoning, Hebei, Shandong, Henan, Shaanxi, , Jiangsu, Yunnan, and Ningxia) in China. The cumulative status and risk characteristics of Cu and Zn were systematically analyzed using the total and available content of the soil. The relationship between the accumulation of available Cu, Zn, and the planting years was fitted to predict the risk of Cu and Zn accumulation exceeding the limit value. The results showed that: 1) The total Cu and Zn exhibited an accumulative characteristic in the protected cultivation soil, except that Cu presented a slight decrease in Jiangsu. The effective state content of Cu and Zn (except that Zn at a relatively rich level both in Shaanxi and Jiangsu) reached an extremely rich level, where there was no state below the critical value. Noted that the soil background values in each province were compared with the abundance and deficiency indexes of soil available trace elements in the agricultural system. 2) The total amount of Cu and Zn in the soil exceeded the standard by 16.03% and 4.58%, respectively, compared with the screening value of farmland soil. The average exceeding limit rate reached 16.92%, while Liaoning, Henan and Yunnan were observed the most serious up to 33.33%, 62.50%, and 32.00%, respectively, compared with the risk limits of soil available Cu and Zn. 3) The risk assessment showed that the overall performance of protected cultivation soil was safe using the effective state. The samples from Liaoning, Henan, and Yunnan reached the level of lightly, lightly pollution, and warning value level, respectively. The cumulative risks of elemental Cu were more serious than Zn element. 4) There was a significant positive correlation between the accumulations of soil available Cu and Zn with the corresponding planting years (P<0.05). The continuous replanting for 6.7, 20.5, and 19.3 years led to the accumulation of available Cu in soils with acidic, neutral, and alkaline limit values of characteristics reach risk, respectively, under the current protected cultivated conditions. At the same time, the continuous replanting for 32.5, 67.9, 91.9 years led to the accumulation of available Zn in the soils with acidic, neutral, and alkaline limit values of characteristic reach risk. The bioavailable state of trace element was used to evaluate the exceeding limit rate of Cu and Zn, while the cumulative risk in the protected cultivated soil, in order to achieve the safe utilization via transforming the excess bioavailable to low state, (such as residue, oxidizable, and reducible state). Therefore, there was a high risk in the accumulations of Cu and Zn in the protected cultivated soil in the practice, where the trends were ever increasing year by year. Consequently, it is necessary to take reasonable and safe measures (including restoration technology and selection of agricultural materials), further to ensure the healthy and sustainable development of protected cultivated agriculture.