鸟粪对同里湿地底泥重金属含量分布及形态影响

Influences of Bird Droppings on Content Distribution and Form of Heavy Metals in Tongli Wetland Sediments

以同里国家湿地公园为研究区,探讨鸟类排泄物对河流底泥重金属全量及形态的影响。选取有鸟粪区域底泥和无鸟粪区域底泥样品,用元素分析仪测定C、N、H、S含量,ICP-OES测定重金属Cr、Ni、Cu、Zn和Co含量,运用Tessier五步法提取可交换态(F1)、碳酸盐结合态(F2)、铁锰氧化态(F3)、有机物结合态(F4)和残渣态(F5),并对两区域底泥潜在生态风险进行了研究。结果表明:C、N、H、S含量在两区域无显著差异,但有鸟粪区域变异系数高于无鸟粪区域。Cr、Ni和Co均呈现有鸟粪区域显著高于无鸟粪区域(P=0.017,0.004,0.001<0.05)。同里湿地底泥重金属形态以残渣态为主,但有鸟粪区域底泥重金属有效态占比高于无鸟粪区域。潜在生态风险评估表明同里湿地底泥中5种重金属单因子潜在生态风险和综合潜在风险值均较低,但有鸟粪区域值较高,其潜在生态风险大于无鸟粪区域。综上,有鸟粪区域底泥的重金属含量以及生态风险高于无鸟粪区域,所以对该湿地鸟粪的清理很有必要。

To study the effects of bird droppings on the total amount and form of the heavy metals in river sediments,samples were collected from regions with and without bird droppings in the Tongli wetland national park,respectively. The contents of C,N,H and S were determined by elemental analyzer. The concentrations of Cr,Ni,Cu,Zn and Co were measured by inductively coupled plasma optical emission spectrometry（ ICP-OES）.The chemical forms of heavy metals were determined by Tessier＇s five step shape extraction method（ F1,F2,F3,F4,F5）. The method proposed by Hankanson for evaluating PER index was applied to the ecological risk assessments. The results showed that： the contents of C,N,H and S in river sediments display no significant differences between these two regions,but the variation coefficients in the region with bird droppings are higher than those in the region without bird droppings. Moreover,the Cr,Ni and Co in the region with bird droppings show significantly higher contents than those in the region without bird droppings（ P = 0. 017,0. 004,0. 001 0. 05）. The forms of heavy metal in Tongli wetland are dominated by the residue state. However,the effective state form of heavy metal in the sediments with bird droppings is higher than that in the sediments without bird droppings. And the potential ecological risk assessments in the region without bird droppings showed that the single factor potential ecological risk and the comprehensive potential ecological risks（ RI） of these 5 heavy metals were low,while as regards to the region with bird droppings the risks are relatively higher. In sum,the heavy metal contents and ecological risks of the sediments in the region with bird droppings are higher than those of the region without bird droppings,and thus it is necessary to clean the bird droppings in the Tongli wetland.