砷和汞在水生蔬菜及其生长环境中的迁移富集

摘要

为研究砷和汞在茭白、菱角植株及其生长环境的迁移富集变化,以“浙911号”茭白品种和“水红菱”为实验材料,采用在土壤中添加砷和汞的处理方法,测定处理后18 d内茭白、菱角器官及水体-土壤中砷和汞的积累量.结果表明:随栽培时间的延长,水体中砷和汞出现不断向土壤、水生蔬菜迁移的趋势,一段时间后达到动态平衡;当砷和汞共处水环境中时,汞的存在会抑制水体中砷向土壤、水生蔬菜迁移.茭白叶、茎中砷和汞含量呈现先升高后降低的趋势,茎是茭白富集重金属的主要器官之一.菱角中砷和汞含量总体呈现上升趋势,最终逐渐向杆、根迁移富集,叶、根是菱角富集重金属的主要器官.茭白和菱角对水体中砷和汞的富集系数远大于对土壤的富集系数,且对汞的富集能力都大于砷;茭白不同器官富集能力:茎＞叶;菱角不同器官富集能力:根＞叶(杆).说明砷和汞在水生蔬菜及生长环境中的迁移与富集能力因蔬菜种类、器官类型及重金属种类的不同而存在明显的差异.%The migration and enrichment of arsenic and mercury in aquatic vegetables,including Zizania latifolia (Zhejiang No.911),red Water caltrop,and their surroundings were studied.By adding arsenic and mercury solution in the soil,the content was measured in 16 days after treatment.The results showed that:as the growth time increased,there was a trend that arsenic and mercury steadily moved from water to soil and aquatic vegetables,which would reach a dynamic equilibrium after some time.When arsenic and mercury were both in water,mercury added in water inhibited the migration of arsenic from water to soil and aquatic vegetables.For migration of arsenic among water,soil and aquatic vegetables was active,arsenic absorbed by soil,which were re-dissolved,would be absorbed by aquatic vegetables,while a lot of mercury were absorbed into the soil.The content of arsenic and mercury in the leaves and stems of Zizania latifolia showed a trend of first increase and then decrease,and stem was one of the organs accumulating arsenic and mercury.The arsenic and mercury accumulation amounted in Water caltrop showed increasing trend,and leaf was significant organ accumulating arsenic and mercury,moreover,arsenic and mercury in water and soil accumulated in the roots and stems gradually.Bioaccumulation coefficient in water was far more than the soil,and mercury enrichment capacity was greater than arsenic;The enrichment capacity of Zizania latifolia organs was stems ＞ Ieaves,while that of Water caltrop was roots ＞ leaves (stems).It was concluded that arsenic and mercury migration and accumulation ability varied from vegetable species,aquatic habitat,the type of organ and heavy metal species.