风浪扰动对太湖水体悬浮物重金属含量的影响

Effects of wind-wave disturbance on heavy metal contents in suspended solids of Lake Taihu

通过离心浓缩的方法,获取太湖梅梁湾口东岸处(即梅梁湾与贡湖湾的交界处)不同风浪条件下的悬浮颗粒物．冷冻干燥,微波消解,ICP-AES的方法测定了其中Co、Cr、Cu、Ni、Pb、Zn等重金属元素及Al、Ca、Fe、Mn等相关金属元素的含量．结果发现,小风浪(2 m/s)、中风浪(7 m/s)和大风浪(11 m/s)下：①水体总悬浮颗粒态金属的量依次大幅度增加；②单位悬浮颗粒物中各金属元素的含量在不同风浪下变化不同．Ca在小、中、大风浪下含量依次增大；Zn在小、中、大风浪下含量依次减少；Mn和Cu的含量变化趋势相同：与小风浪相比,中风浪下Mn、Cu的含量显著增大；与中风浪相比,大风浪下含量显著减少；其它元素Al、Fe、Ni、Pb、Co、Cr等在单位悬浮物中,中风浪与小风浪相比含量减少,大风浪与中风浪相比含量略微增加．研究表明：①金属元素在水体总悬浮物中的含量主要受风浪影响,但风浪对单位悬浮物中金属含量的影响则因元素而异；②除Cu、Mn、Zn外,悬浮物中重金属含量随粒径增大含量减少．

Surface water was taken from the east shore of the mouth of Meiliang Bay, Lake Taihu. The lake water was sampled under weak （2 m/s）, modest （7 m/s） and strong wind- wave （ 11 m/s）, respectively. Suspended solids （SS） were obtained by centrifuging 25L surface water. SS were further freeze-dried and microwave digested, and the contents of Co, Cr, Cu, Ni, Pb, Zn, Al, Ca, Fe, Mn in SS were determined by ICP-AES. It was found that the particulate metal amounts increased gradually with wind speed. Moreover, different metal contents in SS showed different variation trend with wind speed. The contents of Zn in SS decreased with wind speed; the contents of Mn and Cu were highest at middle wind speed; and contents of Al, Fe, Ni, Pb, Co, Cr were lowest at the middle wind speed. These results suggested the metal contents in the shallow lake water were mainly influenced by wind-wave disturbance.