摘要
1993年,波罗的海诸国之间相互合作,共同进行了波罗的海沉积物中多氯联苯(PCB)的大规模调查。地表沉积物中PCB(IUPAC#52,101,118,105,153,138,180)从北(平均213ng/gC)至南(平均382ng/gC)呈增加趋势,表明了大气的影响。与远海生物群中PCB的下降趋势相反,波罗的海本体中已确定年代的沉积物中的PCB在最近几十年中呈增加趋势或持续富集。岩心内同类物格局显示在20世纪没有变化。在假定年际干物质沉积发生变化的条件下,重新计算了PCB沉积,结果发现PCB沉积物的沉淀趋势与所观察到的波罗的海生物群中的PCB富集趋势是一致的,只不过近几十年来沉积物中减少得较少。PCB的沉积物埋藏计算表明,波罗的海本体的纹层沉积是有效的捕集剂;质量平衡表明,水体中PCB的保留时间少于1年。
In 1993, a large-scale investigation of polychlorinated biphenyls (PCBs) in Baltic Sea sediments was performed in cooperation between the Baltic states. sPCB (IUPAC # 52, 101, 118 105, 153, 138, 180) in surficial sediments increased from north (mean 213 ng g-1 C) to south (mean 382 ng g-1 C), indicating atmospheric influence. In contrast to decreasing PCB trends in pelagic biota, the sPCB in dated sediment cores from the Baltic proper showed increased or constant concentrations during recent decades. Down-core congener patterns showed no changes during the 20th century. After re-calculation of sPCB deposition, assuming interannually variable dry matter deposition, the sPCB sediment deposition trend matches the observed sPCB concentration trend in Baltic biota although the reductions in recent decades are less for the sediments. A calculation of sediment burial of sPCB indicated that laminated Baltic proper sediments are efficient traps, and a mass balance showed that the sPCB retention time in the water mass is less than one year.
