摘要
本文用取自波罗的海的生物基质和取自缺氧的波罗的海沉积区域(没有生物扰动)的经过年代测定的沉积物岩心纹层对渡罗的海的污染进行了时ΣDDT和PCB的时间趋势对比研究。对岩心中代表各个年代的连续纹层的化学分析与在每年取样和分析基础工对波罗的海生物的长期时间趋势监测结果进行对比。对波罗的海沉积物岩心的早期研究结果往往显示近期卤化有机化合物的富集有所增强,但是另一方面,对波罗的海生物相的监测显示自70年代以来富集有所减少。在目前的研究中从波罗的海本体西北部取得的两块沉积物岩心显示富集(干重为基准的)的峰值与生物相的出现在同一时段,但是最近数千年来的下降比生物相要缓慢。在代表1940～1950时段的纹层中,发现PCB和ΣDDT的富集程度都非常高。有趣的是在这些老的纹层中还发现了很高比例未代谢的DDT,而1960～1970年的代表层显示未代谢的DDT比例很低,且1970～1998时间段内DDE和DDD代谢物的比例很高。对这些结果与沉积物的再悬浮,沉积物岩心中的卤化有机化合物的扩散与隙间搬运之间的关系进行了讨论。结果显示了沉积物再悬浮的重要性及碳杯准化数据奉适用于解释时间趋势。结果还表明我们没有合适的模型去通过卤化有机化合物,通过使用取自缺氧的沉积物岩心的纹层去回溯解释波罗的海的污染,但是我们急需更多的有关沉积物中重要的沉积机制的知识。
Comparative temporal trend studies of IDDT and PCB on the Baltic pollution, using matrices from Baltic biota and dated lamina from sediment cores in anoxic sediment areas of the Baltic (no bioturbation) have been carried out. Chemical analyses of consecutive laminas of the cores representing individual years were compared to long-term temporal trend monitoring of Baltic biota'based on annual sampling and analyses. Earlier studies of sediment cores from the Baltic have often indicated increasing concentrations of halogenated organic compounds in recent time whereas monitoring of Baltic biota showed decreasing concentrations from the 1970s and onwards. In the present study two sediment cores from the northwestern Baltic proper indicate a concentration (dry weight basis) peak in the same time period as for biota, but the decrease during recent decades is slower than for biota. In lamina representing the period 1940-1950 remarkably high concentrations of both PCB and LDDT were found. Interestingly also a high proportion of nonmetabolized DDT was found in these old lamina, whereas lamina representing 1960-1970 showed a low portion of nonmetabolized DDT and high portions of the metabolites DDE and DDD during the period 1970-1998. The results are discussed in relation to resuspension of sediments, diffusion and interstitial transport of halogenated organic compounds in the sediment cores. The results indicate the importance of resuspension of sediment and that carbon normalized data are inappropriate for interpretation of temporal trends. The results also show that we have no appropriate model to interpret the pollution of the Baltic by halogenated organic compounds, retrospectively, by using lamina from anoxic sediment cores, but that we urgently need more knowledgfe on the important retention mechanisms in sediment.
