荣成天鹅湖沉积物中重金属的分布特征研究

通过对表层沉积物中重金属及粒度的分析,研究了荣成天鹅湖重金属的含量水平及分布特征,并对沉积物的环境质量进行了初步评价。结果表明,天鹅湖重金属的总体水平较低,Cd、Cr、Pb、Cu、Zn的平均含量均低于国家海洋沉积物I类质量标准,其中Cr和Pb存在轻度污染。Cd、Cr、Ni、Pb、Cu、Zn的含量范围分别为0～0.84、1.75～116.11、1.50～29.06、17.36～27.25、2.00～34.98mg.kg-1和11.48～92.61mg.kg-1,平均含量排序为Zn〉Cr〉Pb〉Cu、Ni〉Cd。天鹅湖重金属的富集状况与沉积物的粒度以及人类活动密切相关,大部分元素的高值区出现在颗粒较细的湖中央以及污染严重的西北部,东南部含量较低。相关分析表明,各重金属之间的相关性较好,其中Cd、Cu、Mn、Zn、Fe间呈高度的正相关,空间分布规律相似;重金属与有机质、粘粒含量呈极显著正相关,而与砂粒呈极显著负相关。根据加拿大制定的沉积物评价标准,天鹅湖沉积物中Cr具有较大的生态危害性。

Distribution Characteristics of Heavy Metals in Surface Sediments of Rongcheng Swan Lake,China

Rongcheng Swan Lake,a natural shallow lagoons,is located at the eastern end of Shandong Province,and is connected to the Rongcheng Bay through a narrow channel in southeast lake.The ecological environment in Swan Lake wetland has been destroyed due to the over-exploitation and wastewater discharge during the past few decades.Lake sediments play an important role in the assessment of heavy metal contamination in most lakes.In the present study,surface sediment samples were collected from 20 sites in the whole lake in 2009.Heavy metals,organic matter concentrations and grain sizes in sediments were measured to study the distribution of heavy metals and its affecting factors,and environmental quality of sediments was evaluated also in Swan Lake.The results showed that heavy metal concentrations of sediments were low,and levels of Cd,Cr,Pb,Cu and Zn were superior to the national primary standard of marine sediment quality.Slight contamination was observed in Cr and Pb in Swan Lake.The concentrations of Cd,Cr,Ni,Pb,Cu and Zn changed at the range of 0~0.84,1.75~116.11,1.50~29.06,17.36~27.25,2.00~34.98 mg.kg-1 and 11.48~92.61 mg.kg-1 respectively,and the mean concentrations followed a order of FeMnZnCrPbCu、NiCd.The accumulation of heavy metal had a close relationship with sediment sizes and anthropogenic load in this area.For the most elements,high levels were found in the sediments of central and northwest part of the study area,where grain sizes of sediments were fine and external pollution was serious respectively;while low concentrations were found in those of the southeast area.The correlation among heavy metals was very good,and a highly significant correlation was observed among Cd,Cu,Mn,Zn and Fe,whose spatial distributions were similar.Heavy metals had a significant positive correlation with organic matter and clay concentrations,and a significant negative correlation with sand concentrations.According to the evaluation standard of sediments made in Canada,the potential ecological risk of Cr in sediments was high in Rongcheng Swan Lake.