重庆市某典型区域土壤和水稻中重金属含量研究

Study on Heavy Metal Contents in Soil and Brown Rice Samples of a Typical Area in Chongqing

2019年按点位采集稻田土壤及其对应的水稻糙米样品,对重庆市某典型水稻重金属含量超标区域进行镉、铬、镍、铜、锌、铅、汞和砷8种污染元素含量的监测。结果表明:该区域18个点位中有77.8%的点位土壤镉含量超过风险筛选值,超标倍数范围为0.02~0.65;除镉之外,其余7项元素均未超过风险筛选值;由Nemerow综合污染指数可知,18个点位中有44.4%的点位土壤处于轻度污染水平,存在土壤镉污染风险,应加强土壤环境监测和农产品协同监测;各点位的水稻糙米中铜、锌、汞和砷含量均未超过限量值,但镉、铬、镍和铅均有超标,超标比例分别为5.6%、16.7%、16.7%和22.2%;由富集系数可知,调查区域水稻糙米对重金属的富集能力由高到低排列依次为锌>镉>镍≈铜>铬>铅≈砷,其中锌和镉极易从土壤中被水稻糙米吸收,吸收比例分别为12.3%和11.3%。

Paddy soils and their corresponding brown rice samples were collected by point sampling from a typical heavy metal contaminated area of Chongqing for the assay of cadmium,chromium,nickel,copper,zinc,lead,mercury and arsenic contents in 2019.The results showed that 77.8%of 18 sites in the typical area exceeded the risk screening value by 0.02-0.65 times in soil cadmium content.The other 7 elements did not exceed the risk screening value except cadmium.According to the Nemerow pollution index,the proportion of light pollution was 44.4%of 18 sites,existing a risk of soil cadmium pollution,so collaborative monitoring of soil environment and agricultural products should be strengthened.The contents of copper,zinc,mercury and arsenic in brown rice samples of all sites did not exceed the limit value,but 5.6%,16.7%,16.7%and 22.2%of brown rice samples respectively exceeded the national safety standard of cadmium,chromium,nickel and lead contents.The enrichment capacity of brown rice to heavy metals is zinc>cadmium>nickel≈copper>chromium>lead≈arsenic.Zinc and cadmium are easily absorbed by brown rice from the soil,and the absorption ratio is 12.3%and 11.3%,respectively.