连环湖敖包泡沉积物磷形态垂向分布特征

应用SMT连续提取法对连环湖敖包泡北部(AB1)和南部(AB2)柱状沉积岩芯中磷形态的含量和垂向分布特征进行对比分析,结合沉积岩芯年代测定,探讨了该湖区沉积物中磷的演化特征与人为污染历史以及内源磷的释放风险。结果表明,AB1、AB2沉积物中磷形态的含量和垂向变化不同,AB1沉积物中各形态磷含量均高于AB2,且随深度变化波动较大。20世纪40年代中期至1981年,AB1沉积物各形态磷和OM含量波动较大;AB2沉积物中Ca-P、IP、TP含量呈先增加后减少之势,Fe/Al-P、OP、OM含量变化较稳定。1981—2009年,AB1沉积物Ca-P、IP、OM含量变化较小,Fe/Al-P、OP、TP含量相对波动较大;AB2沉积物Ca-P、Fe/Al-P、TP含量不同程度上先增加后减少,IP、OP、OM含量变化均呈增加趋势。连环湖敖包泡沉积物磷人为来源以工业废水、居民生活污水和农药化肥的流失为主。湖泊北部磷含量高于南部,这与人类活动强度密切相关,敖包泡北部附近村落密集而南部没有村落。应用单一因子标准指数法对湖泊表层沉积物磷素进行生态风险评价表明,湖区北部表层沉积物总磷含量超标,存在一定的安全风险,同时AB1沉积物上部较底部活性磷(Fe/Al-P和OP)增加较多、且活性磷(Fe/Al-P和OP)是AB1沉积物磷增加的主要形态,因此连环湖敖包泡沉积物中磷向上覆水体释放的风险增加,对湖泊水体的富营养化的影响应予以关注。

Vertical Distribution Characteristics of Phosphorus Fractions in the Sediments from Aobao in Lianhuan Lake

The contents and vertical distribution of phosphorus fractions were analysed comparatively for core sediment samples taken from north sampling site for Core AB1 and south sampling site for Core AB2 of Aohao Lake in Lianhuan Lake using the SMT sequential extraction method.With the dating approach,the evolution characteristics and polluted history of phosphorus and the risk of phosphorus release in lake sediments were discussed.The results showed that the contents and vertical distribution of phosphorus fractions in Core AB1 and Core AB2 varied and the contents of phosphorus fractions in Core AB1 were higher than those in Core AB2,with fluctuated significantly with the depth.During the mid-1940s and 1981,the contents of phosphorus fractions and OM in Core AB1 showed large fluctuations;the contents of Ca-P,IP,and TP in Core AB2 first increased and then decreased,while the contents of Fe/Al-P,OP,and OM were relatively constant.During 1981 to 2009,the contents of Ca-P,IP,and OM changed less and the contents of Fe/Al-P,OP,and TP showed relatively large fluctuations in Core AB1;the contents of Ca-P,Fe/Al-P,and TP first increased and then decreased to different degrees and the contents of IP,OP,and OM tended to increase in Core AB2.The sources of phosphorus in core sediments of Aobao Lake were mainly from industrial wastewater,sewage,and the loss of pesticides and fertilizers.The content of phosphorus in the north of the lake was higher than that in the south,which was closely related with human activity.There were several villages in the northern part of the Aobao Lake but none in the southern part.By using single factor standard index method,the assessment of ecological risk of phosphorus in surface sediments showed that the content of total phosphorus in the northern part of the lake exceeded the standard and showed a certain safety risk.Meanwhile,active phosphorus (Fe/Al-P and OP) in the upper part of the sediment showed a greater increase than that at the bottom of Core AB1,and active phosphorus (Fe/Al-P and OP) were the dominant fractions of the increasing phosphorus sedimentation in Core AB1.It was indicated that phosphorus in the sediment in Aobao Lake would release more easily to the overlying water,and the effect on the eutrophication of lake water should be given attention.