我国南方水稻产地镉环境质量类别划分技术

针对我国耕地质量类别划分技术及方法体系不完善的现状,提出应用物种敏感性分布法（SSD）基于不同保护率建立"优先保护类、安全利用类和严格管控类"的土壤镉划分阈值,并对其合理性和科学性验证.结果表明,我国南方水稻产地土壤pH、土壤有机质（SOM）和阳离子交换量（CEC）对水稻富集镉的影响均达到了极显著水平（P<0.01）,并由其构建的三因子生物有效性模型可解释水稻富集系数62.0%的变异;水稻对镉的SSD曲线表明,不同水稻品种对镉的敏感性差异明显,主要与其基因型相关;依据SSD曲线基于保护率为80%和5%推导出我国南方水稻产地"优先保护类和严格管控类"的土壤镉划分阈值分别为0.26 mg·kg^-1和1.67 mg·kg^-1,且当土壤镉≤0.26 mg·kg^-1时划分为优先保护类耕地,土壤镉≥1.67 mg·kg^-1时划分为严格管控类耕地,土壤镉介于0.26~1.67 mg·kg^-1时划分为安全利用类耕地,并通过134组独立数据验证其具有一定合理性和科学性.本研究表明应用SSD法对我国南方水稻产地镉环境质量类别划分时体现出较好的普适性、科学性和合理性,同时可为我国农用地土壤环境质量类别划分技术及方法体系的建设和完善奠定坚实的工作基础.

Technological Classification of Cadmium Quality in the Rice Producing Areas of South China

Classifying the quality of agricultural products is an important means of managing the arable land quality and guaranteeing the quality and safety of agricultural products. This work is planned to be completed in 2020. However, there is still no perfect method or technology for classifying the quality of arable lands. The species sensitivity distribution (SSD) has become commonly used for determining ecological safety thresholds since it takes into account differences in species sensitivity, the physical and chemical properties of soils, biological availability, and sources of pollutants. However, it has not yet been applied to the classification of arable land quality. Therefore, based on the routine monitoring data of rice production areas in southern China from the Agro-environmental Monitoring Center of China, this study proposes the use of species sensitivity distributions to classify the environmental quality of cadmium in rice production areas. The scientific rationale of this method was also discussed in order to provide an important reference for the construction and improvement of the classification system for arable land quality in China. The results showed that the pH, soil organic matter, and cation exchange capacity of the physical and chemical properties of soils significantly affected the enrichment of cadmium in rice, and this relationship was used to establish the cadmium transfer equation in the soil-rice system. It was found that there were obvious differences in the cadmium enrichment abilities of different rice varieties, which were mainly caused by the differences in their genotypes. According to the species sensitivity distributions, soil cadmium thresholds were obtained, which yielded a priority protection class of less than 0.26 mg·kg^-1 and strict control class of greater than 1.67 mg·kg^-1, between which are the safe use classes. The results were verified through independent datasets, and it was found that the application of species sensitivity distributions to classify the environmental quality of cadmium in rice producing areas reflected good scientific rationale and operability. This study may provide a foundation for the construction and improvement of the arable land quality classification system in China.