近200年桑沟湾养殖海域柱状沉积剖面的污染有机质记录与评价

Study of sedimentary section records of organic matter in Sanggou Bay over the last 200 years

通过对取自桑沟湾南部和北部养殖海域2个站位的柱状沉积物样品进行TOC和TN测定,分析了桑沟湾沉积物中TOC和TN的分布情况,结合沉积物年代序列的测定,估算了工业革命之前、之中及规模化养殖之后桑沟湾海域沉积物中水生有机碳和总氮的含量,并对近200年来桑沟湾养殖海域有机质沉积情况进行了评价。结果显示:19世纪70年代以前,TOC含量较稳定,TN含量随深度增加而缓慢降低;19世纪70年代至20世纪70年代,TOC,TN含量波动均较大;20世纪70年代以后,TOC含量逐渐减小并趋于稳定,TN含量随养殖规模的扩大显著增加,且扇贝养殖区表层沉积物中TOC,TN的含量均低于海带养殖区。近200年桑沟湾沉积物中有机质来源变化趋势为混源-陆源-混源,近40年来的规模化养殖明显增加了水生有机碳及水生总氮在TOC和TN中所占比例。对桑沟湾沉积物中有机质污染评价结果显示,大规模的养殖活动增加了底质中沉积物TOC和TN的含量,海带筏式养殖对沉积物中的TN造成了一定的累积性自身污染。

For study of sedimentary section records of organic matter in Sanggou Bay,the content of TOC and TN of the sediment from two stations was determined.Combined with sedimentary chronosequence,the TOC and TN of aquatic source before the Industrial Revolution,during the Industrial Revolution and after large-scale farming in Sanggou Bay was estimated.Meanwhile,an assessment of the quality of organic matter in the cultivated area of Sanggou Bay was generated.The main results are as follows： before the Industrial Revolution,TOC was steady relatively,but TN decreased slowly with increasing depth;during the Industrial Revolution,fluctuation of TOC and TN were both great;after the large-scale farming,TOC decreased gradually and stabilized,and TN increased significantly with the expansion of farming,moreover,TOC and TN in surface sediments in scallop farming area were lower than that in the kelp farming area.The change tendency of the source of organic matter was mix source-terrigenous source-mix source.In addition,the percentage of TOC and TN of aquatic source increased due to the action of large-scale farming,and there was a cumulative pollution of nitrogen in the kelp ocean-based cultivation area.