摘要
为了解高地质背景区稻鱼共生系统中汞的潜在环境和健康风险,本研究选取贵州省喀斯特地质高背景区黔东南丹寨县、麻江县和非喀斯特地区从江县、榕江县和锦屏县为研究对象,采集稻鱼共生系统中稻田土壤、稻米和稻花鱼样品,测定总汞(THg)和甲基汞(MeHg)含量.采用地累积指数法和潜在生态风险指数法评估土壤环境风险;通过稻米和稻花鱼MeHg含量及不同年龄段居民膳食摄入情况,评估了居民摄入稻米和稻花鱼的汞暴露风险.结果表明:喀斯特地区土壤THg和MeHg含量均高于非喀斯特地区,但其甲基化率却弱于后者;喀斯特区域分别有28％和37％的稻田土壤样品THg含量超过我国水稻生产土壤汞阈值标准(0.65 mg·kg-1)和农用地水田土壤污染风险管控标准(0.50 mg·kg-1),而非喀斯特区域土壤均未超标.土壤生态风险评估结果显示:喀斯特地区土壤的汞污染水平和生态风险更高.喀斯特地区稻米THg和稻花鱼MeHg含量分别为(5.15±4.19)ng·g-1 和(32.80±23.05)ng·g-1,高于非喀斯特区域分别为(3.43±0.87)ng·g-1 和(11.77±7.08)ng·g-1,但稻米汞的富集系数更低,鱼米汞含量均低于我国食品安全标准限值规定的THg 0.02 mg·kg-1和MeHg 0.50 mg·kg-1.居民膳食风险评估表明:"稻米+稻花鱼"食用模式的居民风险值HQ较高,且随居民年龄增加而降低,女性高于男性,但总体HQ＜1,对居民没有汞暴露风险.以上结果表明,地质高背景区的稻鱼共生系统整体呈现低风险水平.
Abstract
In order to understand the potential environmental and health risks of mercury in rice-fish coculture sys-tems at natural high geologic background areas,we collected soil,rice and fish samples from two Karst areas(Danzhai and Majiang),and three non-Karstic areas(Congjiang,Rongjiang and Jinping)in southeast Guizhou Province,and the total mercury(THg)and methylmercury(MeHg)concentrations in these samples were measured.The environmental pollution risk of mercury in soil was evaluated by geoaccumulation index and potential ecologi-cal risk index,and health risks for residents of different age groups were estimated based on rice and fish MeHg data.Results showed that soil THg and MeHg concentrations in Karst soils were higher than those in non-Karstic areas,while the ratio of MeHg to THg in Karst area,which represents mercury methylation potential,was lower than in the non Karst areas.28％of paddy soil samples from Karst regions exceeded the domestic safety threshold values of soil THg for rice production(0.65 mg·kg-1),and 37％of them exceeded the risk control standard of soil THg in agricultural paddy field(0.50 mg·kg-1),while none of soil samples from non-Karstic areas exceeded the above standards.The ecological risk assessment of soil showed that higher mercury pollution level and ecological hazard occurred in the Karst area.The levels of THg in rice were(5.15±4.19)ng·g-1 and(3.43±0.87)ng·g-1,and fish MeHg were(32.80±23.05)ng·g-1and(11.77±7.08)ng·g-1in the Karst and non-Karstic regions,respectively.The mean rice THg and fish MeHg concentrations in the Karst region were higher than those in the non-Karstic region,however,lower bioconcentration factor(BCF)in rice samples.The THg in rice and MeHg in fish from all the samples,including Karst and non-Karst,were below the national food safety limits,which were 0.02 mg·kg-1 for rice THg and 0.5 mg·kg-1 for fish MeHg.Dietary risk assessment indicated that the HQ via"rice+fish"consumption pattern was higher for residents and decreased with age.The HQ in females was higher than in males,but overall HQ＜1,suggesting that there is no mercury exposure risk to the population.Overall,the results showed that the whole risk level in the rice-fish coculture system from geological high background area was low.
维普
万方数据