抚仙湖表层沉积物AVS与SEM分布特征及其生态风险评估

Distribution characteristic and ecological risk assessment of AVS and SEM in surface sediments of Lake Fuxian

以高原深水抚仙湖为研究对象,分析了全湖16个样点表层沉积物(0～5 cm)的酸可挥发性硫化物(AVS)和同步提取重金属(SEM)的分布特征,并利用∑SEM和AVS的物质的量浓度比对全湖重金属潜在生态风险进行了评估.结果表明:AVS在南北湖区分布存在明显差异,南部湖区分布均匀,平均含量仅为0.074±0.043μmol/g,而北部湖区则由湖岸带向北湖心(N9)呈现出递增趋势,平均含量高达0.317±0.485μmol/g. SEM在南北湖区分布较为集中,南部湖区主要集中在路居河口(S2),北部湖区主要分布在老凹地(N5)和东大河口(N4).除牛摩河口(S5)、梁王河口(N3)和北湖心(N9)外,其余所有点位[∑SEM]/[AVS]>1,且南部湖区平均[∑SEM]/[AVS]值(3.51±1.91)显著高于北湖湖区(2.19±2.10).因此抚仙湖全湖尤其是南部湖区重金属生态风险应引起高度重视.

The concentrations of acid volatile sulfide(AVS)and simultaneously extracted metals(SEM)were analyzed in 16 surface sediment samples(0-5 cm)from Lake Fuxian.The potential ecological risks of heavy metals were also evaluated by the molar ratio of∑SEM to AVS.Results show that obvious distinction of AVS distribution are existed in the south and north lake zone.There is uniform distribution in the south lake zone which has an average AVS concentration of 0.074±0.043μmol/g.However,the north lake zone displays a increasing trend from the littoral to pelagic area(N9)and has an average AVS concentration as high as 0.317±0.485μmol/g.SEM is mainly concentrated at two points,Laoaodi(N5)and Dongda River estuary(N4)in the north lake zone.As for the south lake zone,SEM is mainly concentrated at S2,Luju River estuary.With the exception of Niumo River estuary(S5),Liangwang River estuary(N3)and N9,[∑SEM]/[AVS]of all the remaining sites are higher than 1,and the average[∑SEM]/[AVS]in south lake zone(3.51±1.91)significantly exceeds that in north lake zone(2.19±2.10).Therefore,ecological risk in Lake Fuxian especially in south lake zone should be taken seriously.