水生植物对水体中低浓度^(95)Zr的富集效应

EFFECT OF AQUATIC PLANTS ON ^(95)Zr CONCENTRATION IN SLIGHTLY POLLUTED WATER

采用模拟污染物的同位素示踪技术研究了 3种水生植物对水体中低浓度95Zr的富集效应。结果表明 :( 1 )水生植物 (金鱼藻、卡州萍和水葫芦 )对低浓度水体中的95Zr均具有较强的富集能力 ,富集系数CF值达 5 6 78～ 1 1 2 94,因此这 3种水生植物可作为检测水体95Zr污染的指示生物 ;( 2 )在 95Zr轻微污染的水体中放养水生植物后 ,水中的95Zr比活度随时间呈下降趋势 ,放养 3d就下降了 5 0 % ,因此 ,可用这 3种水生植物净化被95Zr轻微污染的水体 ,其中以水葫芦最为合适 ;( 3)放养水生植物前后 ,底泥中95Zr的比活度和总活度均非常接近 ,仅下降0 5 % ,表明底泥吸附的95Zr不易解吸而进入水体 ,底泥对95Zr具有强烈的吸附和固定作用。因此 。

Effect of three aquatic plants(Ceratophyllum demersum, Azolla caroliniana and Eichhornia crassipes) on 95Zr concentration in slightly polluted water was studied by using isotope tracer techniques. The results showed that the aquatic plants had strong ability of 95Zr concentration in water. The concentration factor (CF) were from 56.78 to 112.94,so three aquatic plants were suggested be bio-indicators for 95Zr polluted water. The specific activity of 95Zr in water decreased with time when the aquatic plants were put in slightly 95Zr polluted water. The descent of specific activity of 95Zr in water was very quick during the beginning period(0～3d). The time for the specific activity reduced to 50% was only 3 days,indicating that thres aquatic plants could be used to purge slightly 95Zr polluted water. The effect of Eichhornia crassipes on purging 95Zr in water was the best among the three aquatic plants. The specific activity of 95Zr in bottom clay only decreased 5% after putting aquatic plants in water,indicating that desorption of 95Zr from bottom clay was not easy. As the bottom clay had strong ability of adsorption and fixation to 95Zr, the effect of aquatic plant on purging 95Zr adsorpted by bottom clay was not visible.