铀尾矿库中重金属元素的生态迁移风险研究

Study on Ecological Migration Risks of Heavy Metals in Uranium Tailings Dam

用ICP-AES方法检测了铀尾矿库内人工修复植被生境与自然修复植被生境覆土中重金属元素镉、铅、铜、锌、锰、铬、镍的含量,同时检测了自然修复植被生境中先锋植物加拿大蓬与鸡眼草茎叶、植食性昆虫蝗虫、蝽与捕食性节肢动物螳螂、蜘蛛体内的镉、铅、铜、锌、锰、铬、镍的含量。结果显示,人工栽植蜈蚣草覆土中镉、铜、锌、锰、铬的含量均显著高于对照土壤、人工栽植苍耳、商陆与自然修复植被覆土中的含量,其中锰、镉、锌与铬的含量分别是对照土壤中的7.6,2.8,1.4,1.8倍。自然修复植被生境覆土中铅的含量显著高于人工栽植苍耳、商陆生境、人工栽植蜈蚣草生境覆土与对照土壤,其锰含量约为对照土壤的2倍。人工栽植苍耳、商陆生境中覆土中锰、铬含量显著高于对照。加拿大蓬与鸡眼草茎、叶中均含有被检测的7种重金属,加拿大蓬茎与鸡眼草茎叶对Zn、鸡眼草叶对Mn具有明显富集作用。蝗虫对铜与铬有一定的富集作用,对镉、铅、锌、锰与镍未表现富集作用。蝽对镉、铅、铜、锌、锰、铬与镍均具有较强的生物放大作用,其中蝽体内Cr的含量是土壤含量的191.26倍。蜘蛛与螳螂体内的重金属含量很高,对7种被检测重金属均具有非常明显的生物放大作用。蜘蛛体内各种重金属的含量显著高于螳螂体内的含量,蜘蛛体内Cd含量是其环境土壤中含量的693.13倍。研究表明,被检测的7种重金属均能从尾矿沙向上层覆土中迁移,且均能沿着"土壤-生产者-初级消费者-次级消费者"生态链迁移。

The content of heavy metals, which were cadmium, lead, copper, zinc, manganese, chromium and nickel in the covering soil sampled from habitats both with artificial vegetation transplanted plants Pteris viitara, Xanthium sibiricopperm and Phytolacca americana and growing spontaneousl vegetation with main plant species Erigeron canadensis and Kummerowia striata in uranium tailing dam, was tested by using the ICP--AES method. The eontent of the same 7 kinds of heavy metals above-mentioned in stem and leaf of plants,which were E. canadensis and K. striata, in herbivorous insects, whieh were locust and stinkbug, in predatory arthropods, which were mantis and spiders all sampled from the habitats with growth natural vegetation in uranium tailing dam, was also tested by using the ICP--AES method at the same time. The results showed that The eontent of cadmium, eopper, zine, manganese and chromium in covering soil sampled from transplanted P. vittata habitats were markedly higher than that in covering soil sampled from transplanted X. sibiricopperm and P. americana habitat, with growing spontaneousl vegetation habitat and control soil, and compared the content of manganese, cadmium, zinc and chromium with that in the control soil, it was the multiples of 7.6, 2.8, 1.4 and 1.8, respectively. The content of lead in eovering soil sampled from the habitats with growth natural vegetation was obviously higher than that in covering soil sampled from transplanted X. sibiricopperm and P. americana, P. vittata vegetation habitat and control soil, and compared the content of manganese with that in the control soil, it was about the multiples of 2. The content of manganese and chromium in covering soil sampled from transplanted X. sibiricopperm and P. americana vegetation habitat remarkably higher than that in contorl soil. Cadmium, lead, copper, zinc, manganese, chromium and nickel were detected both in the stem and leaf of E. canadensis and K. striata. The stem of E. canadensis and the stem and leaf of K. striata could accumulate zinc and the leaf of K. striata could accumulate manganese. Locust could accumulate copper and chromium and could not gather cadmium, lead, zinc, manganese and nickel elements. Stinkbug had strongly biological magnifying, to cadmium, lead, copper, zinc, manganese, chromium and nickel and the content of chromium in the stinkbug was the 191.26 times as that in soil. Both spiders and mantis were excellent accumulators of cadmium, lead, copper, zinc, manganese, chromium and nickel but the content of heavy metals in spiders was higher than that in mantis. The spiders could magnify the content ofcadmium to multiples of 693.13. In conclusion, 7 kinds of heavy metals, cadmium, lead, copper, zinc, manganese, chromium and nickel could migrate from tailings up to covering soil and further transfer along the ecological chain that was from soil to producer, then to primary consumer and finally to the secondary or higher trophie grade.