摘要
本研究系统调查了湖南郴州邓家塘砷污染区水稻田抛荒后自然恢复的植被和旱地 (蔬菜) 两大农业土地利用类型的植物中砷含量, 分析了当地居民砷暴露途径, 并进行污染区健康风险评估。结果表明: 砷污染程度对抛荒农田自然恢复植被类型有显著影响。在轻度污染条件下, 植物物种数量中等但总生物量最大; 在中度污染条件下, 植物物种数量最多; 在严重污染条件下, 植物物种数量最少且总生物量最小。恶性杂草雀稗是自然恢复植被物种丰富度的直接控制因子。当地蔬菜可食部位砷浓度超标现象严重, 呈现出叶菜类 >葱蒜类 >根茎类>果菜类的趋势。人体通过食用蔬菜摄入的砷量在春夏和秋冬季节分别为每日 4 1μg/kg体重和每日 2 9μg/kg体重, 都超过了WHO限定的安全标准 (每日 2 1μg/kg体重)。
Intake excess of arsenic (As) can damage human health and may cause diseases. Routes of As intake are respiratory for dust and fumes, and oral for As in water, soil, beverage, and food. Consumption of vegetables from contaminated soils may be harmful to consumers health. In 1999, a serious As poisoning incident due to As contamination happened, more than 300 people were hospitalized in Dengjiatang, Chenzhou City, Hunan Province. Some 50 ha of paddy fields were contaminated and the farmlands were wasted for 4 years, though the source of As contamination had been cut off by local authority in time. Only a few vegetable fields can still be cultivated on the fields. There are few reports on revegetation or potential risk study of wasted As-contaminated farmland.We investigated the As concentration of plants and soils on the fields with different levels of As contaminations. Processes of natural revegetation of waste paddy and health risk of cosumed vegetables cultivated were investigated in the As-contaminated erea. It was found that revegetation in As-contaminated soil was significantly affected by the As-contaminated level. The amount of plant species was small and the weed biomass was the greatest in soil contaminated with low arsenic. The weeds grown on soil contaminated with medium level of As had the highest amount of plant species. The amount of plant species was the least and biomass of weed was the lowest in soil contaminated with high level of As. The species diversity was reduced by the present of Paspalum sp., a dominated weed, in the wasted fields. As concentrations in the edible parts of most vegetables were higher than the maximal permissible limit of As in food. Intake of As from consumed vegetables was 4.1 μg/kg body wt. per day in spring and summer, and 2.9 μg/kg body wt. per day in autumn and winter, respectively, both of which exceeded the level (2.1 μg/kg body wt. per day) set by World Health Organization (WHO).
出处
《地理研究》
CSCD
北大核心
2005年第1期151-159,共9页
Geographical Research
基金
国家杰出青年基金项目(40325003)
国家重点基础研究前期研究专项(2002CCA03800)
国家高新技术研究发展计划(2001AA645010)
国家自然科学基金(40232022)