Qu Mingkai, Li Weidong, Zhang Chuanrong, Huang Biao, Zhao Yongcun
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, 210008 Nanjing, China.
Department of Geography and Center for Environmental Sciences and Engineering, University of Connecticut, Storrs, Connecticut 06269.
Sci Rep. 2015 Dec 17;5:18451. doi: 10.1038/srep18451.
The accumulation of a trace metal in rice grain is not only affected by the total concentration of the soil trace metal, but also by crop variety and related soil properties, such as soil pH, soil organic matter (SOM) and so on. However, these factors were seldom considered in previous studies on mapping the pollution risk of trace metals in paddy soil at a regional scale. In this study, the spatial nonstationary relationships between rice-Cr and a set of perceived soil properties (soil-Cr, soil pH and SOM) were explored using geographically weighted regression; and the relationships were then used for calculating the critical threshold (CT) of soil-Cr concentration that may ensure the concentration of rice-Cr being below the permissible limit. The concept of "loading capacity" (LC) for Cr in paddy soil was then defined as the difference between the CT and the real concentration of Cr in paddy soil, so as to map the pollution risk of soil-Cr to rice grain and assess the risk areas in Jiaxing city, China. Compared with the information of the concentration of the total soil-Cr, such results are more valuable for spatial decision making in reducing the accumulation of rice-Cr at a regional scale.
水稻籽粒中微量金属的积累不仅受土壤微量金属总浓度的影响，还受作物品种以及相关土壤性质（如土壤pH值、土壤有机质等）的影响。然而，在以往关于区域尺度稻田土壤微量金属污染风险制图的研究中，很少考虑这些因素。本研究利用地理加权回归探讨了水稻-铬与一组可感知土壤性质（土壤-铬、土壤pH值和土壤有机质）之间的空间非平稳关系；然后利用这些关系计算土壤-铬浓度的临界阈值（CT），以确保水稻-铬浓度低于允许限值。随后定义了稻田土壤中铬的“承载能力”（LC）概念，即CT与稻田土壤中铬实际浓度的差值，从而绘制土壤-铬对水稻籽粒的污染风险图，并评估中国嘉兴市的风险区域。与土壤总铬浓度信息相比，这些结果对于在区域尺度上减少水稻-铬积累的空间决策更有价值。
