【摘要】 镉(Cd)是一种剧毒重金属元素,可引起呼吸系统、肾损伤等多种疾病,对人体毒性极高,可通过多种途径暴露于人体,危害人体健康。土壤-植物-食品-人的迁移途径在人类对环境镉的暴露中占主导地位。近年来,Cd通过饮食途径对人体健康造成的风险日益引起人们的关注和重视。本文在对研究区不同土地利用类型下土壤和作物进行大规模采样调查的基础上,对其蔬菜、水稻、旱地、果园等4种土地类型土壤及其种植作物中镉含量积累进行了研究。结果表明,菜地和水稻地有明显的污染超标现象,其中菜地土壤镉含量最高。根据不同土地利用类型下各作物镉富集系数,进行聚类分析,比较其对镉富集能力的差异,结果表明水稻地稻米镉的富集能力最高,单独划为一类。利用定性风险分析技术,对不同土地利用类型下土壤镉对人体健康的风险商值进行了计算,结果表明不同土地类型下,作物镉风险商值为水稻>深色蔬菜>浅色蔬菜>水果>玉米。镉对个人致癌年风险的计算结果表明,水稻个人年致癌风险为0.6270×10-4/年,高于防护委员会(ICRP)推荐的最大可接受年风险水平0.5×10-4/年,为不可接受水平,居民面临较大的致癌风险,应采取积极措施对研究区土壤镉污染进行治理和修复。更多还原

【Abstract】 Cadmium is a toxic heavy metal from both natural and manmade sources. Cadmium is poisonous to humans,and is known to cause lung and prostate cancer and is toxic to the gastrointestinal tract,kidneys,respiratory,cardiovascular and endocrine systems.In the environment,cadmium can cause adverse effects on human health through many exposure pathways.Cadmium transfer via soil-plantfood-human is ranked as the dominant pathway for human exposure to cadmium.In recent years,risks of cadmium to human health through the food chain have been a topic of wide concern.Such information is important for the understanding of food safety and human health.This study is based on a large-scale survey of cadmium concentration in soil and crops under four different land use types in the study area.We analyzed the accumulation characteristics of cadmium levels in the soil and crops of vegetable fields,paddy fields,dry land and orchards.Cadmium concentrations were measured using graphite furnace atomic absorption spectrometry.The mean cadmium concentration was highest in the vegetable field.Of the four land use types,the level of soil cadmium pollution of the vegetable fields and paddy fields were clearly higher than the standard.With the enrichment factors of cadmium by crops under different land use types,hierarchical cluster analysis was done to compare the difference in cadmium accumulation.The results indicated that land use greatly affected the accumulation of cadmium in crops.Rice in paddy fields was the strongest in accumulating cadmium,which can be independently classified in the hierarchical cluster.Based on qualitative risk assessments,hazard quotients of soil cadmium to human health in the four different land use types were analyzed.The hazard quotients of crops under different land use type were in the order: rice>dark vegetable>light vegetable>fruit>maize.In addition,the results show that the annual carcinogenic risk of rice to individual human health was 0.627×10^-4/a,which is much higher than the acceptable risk threshold of 0.500×10^-4/a as recommended by the International Commission on Radiological Protection.The health risks caused by cadmium in soil and rice system are unacceptable,and people living in the study area were faced with high carcinogenic risk.Active measures should be taken to control and remediate soil cadmium pollution in the study area.更多还原