湛江水稻生产环境及其稻米中Cd的安全性评价

Safety Evaluation of Cadmium in Rice Production Area:A Case Study in Zhanjiang City of Guangdong Province,China

为研究湛江稻米生产环境及其稻米中Cd的安全性,抽样测定了湛江4个水稻主产区的大田土壤、灌溉水、植株器官和稻米中重金属镉(Cd)的含量。结果表明:早稻与晚稻均表现为,Cd在根中的积累量显著地高于茎、叶和稻米。同时,Cd在稻米中的积累量显著地低于茎、叶,Cd在茎、叶中的含量水平相当,水稻植株器官对Cd的富集水平基本为根>叶>茎>稻米,根系是吸收和积累Cd的主要植株器官;湛江市4个水稻主产区生产的稻米中Cd的含量范围为0.034～0.047mg.kg-1,符合国家粮食卫生控制标准值(GB2715—2005),尚不存在Cd暴露的风险。水稻种植区的土壤中Cd含量为0.155～0.180mg.kg-1,达到国家土壤环境质量一级标准(GB15618—1995),仍属于自然背景值范围;灌溉水的重金属Cd含量的范围为0.0019～0.0049mg.L-1,均达到国家农田灌溉水标准(GB5084—2005)的要求。因此,湛江市水稻生产的土壤和灌溉水环境是安全的,生产的稻米Cd的安全性高,不会危害消费人群的身体健康。

As the main rice producing base in Guangdong Province, Zhanjiang has the rice planting area about 220,000 hm2 and total yields of 1.1 million tons. To investigate Cd level in the rice growing environments and grains of Zhanjiang City, paddy soil and irrigation water samples together with rice plants and grains were analyzed. Results indicated that the accumulation of Cd in roots of spring rice or autumn rice was significantly higher than that in stems, leaves or grains, and the grains had the lowest content of Cd. Meanwhile, the content of Cd in stems and leaves was almost equal. The level of Cd in the rice organs was found to decrease as the following order：root〉leaf〉stem〉grain, which clearly indicated that Cd was mainly accumulated in roots. In addition, Cd contents in rice grains from the four main production areas of Zhanjiang varied from 0.034 mg. kg^-1 to 0.047 mg＂ kg^-1, which met the national hygienic standard for grains of China（ GB 2715-2005 ）. According to the Environmental Quality Standard for Soils in China（ GB 15618-1995 ）, the paddy soil quality was excellent because the concentrations of Cd did not exceed its background value and ranged from 0.155 rag＂ kg^-1 to O. 180 mg＂ kg^-1. The concentration of Cd in the irrigation water quality varied from 0.001 9 mg·L^-1 to 0.004 9 mg＂ L^-1, which met the Standards for Irrigation Water Quality（ GB 5084-2005 ）. In brief, the qualities of rice growing environments and grains in Zhanjiang city were safe, which would not pose a threat to peoples＇s health.