低浓度富里酸对底泥中重金属铅的生物有效性影响

Effects of Trace Fulvic Acid on Bioavailability of the Heavy Metal Lead in Sediment

通过向模拟水生生态系统添加低浓度的富里酸(FA),考察其对重金属铅的生物有效性影响,并试图找出铅在鲫鱼组织中的分布规律。结果表明,低浓度的FA能够对底泥中的铅起到活化作用,使从底泥中解吸出来铅浓度增大。鲫鱼各组织器官对铅的蓄积作用均表现为在同一污染浓度下,加入FA的大于未加入FA的;在不同污染浓度下,高浓度的大于低浓度的,且在加入FA后这种蓄积作用的增大效应也将进一步增大。铅在鲫鱼组织中的分布规律为:鱼肝>鱼鳃>鱼鳞、鱼皮>鱼肉,但是鱼血对铅的蓄积作用与其他器官的差异性较大。

Previous studies have shown the importance of humic substance in increasing the solubility and toxic heavy metals, but the bioavailability of the heavy metal when the ratios of humic acid （HA） and fulvic acid（FA） changed in the freshwater was little researched. A method stimulating aquatic ecosystem was used to determine the effect of trace fulvic acid （FA） on the bioavailability of lead to carassius auratus. Lead was applied into sediment with two concentrations of 100 and 500 mg· kg^-1, fulvic acid （FA） of 5 mg· L^-1 was added in the aquatic ecosystem. At the end of the two-months experiment, the trace fulvic acid could activate the heavy metal lead, and caused the increase of the lead desorption concentration from the sediment. The accumulation content of all the carassius auratus tissue organs were as follows： under 100 mg·kg^-1 and 500 mg·kg^-1 lead treatment of added trace fulvic acid compared with the control, about 0.38-1.32 μg·g^-1 and 1.10-3.81 μg·g^-1 were increased in fish muscle and fish liver respectively （P〈0.05）. The lead content at the treatment of 100 mg·kg^-1 increased in a range of 1.35-4.31 μg·g^-1 from fish muscle to fish liver respectively compared with the low concentration treatment, it was in a range of 2.07- 6.97 μg·g^- 1 when added fulvie acid. Although the treatment of fish blood was different from other organs, it also had the similar results. The accumulation of the lead in earassius auratus tissues followed the order： fish liver〉fish gill〉fish scale, fish skin〉fish muscle, but the aeeumulation of the lead in fish blood was evidently different from other organs.