Grimalt Joan O, van Drooge Barend L, Ribes Alejandra, Vilanova Rosa M, Fernandez Pilar, Appleby Peter
Department of Environmental Chemistry, Institute of Chemical and Environmental Research (ICER-CSIC), Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain.
Chemosphere. 2004 Mar;54(10):1549-61. doi: 10.1016/j.chemosphere.2003.09.047.
The composition of persistent organochlorine compounds (OC) in soils and sediments from two high altitude European mountain lakes, Redon in the Pyrenees and Ladove in the Tatra mountains, has been studied. Sediment cores from two additional lakes in the Tatra mountains, Starolesnianske Pleso and Dlugi Staw, have also been examined. DDTs (1.7-13 ng g(-1)) were the most abundant OC in soils followed by total polychlorobiphenyls (PCBs; 0.41-1.5 ng g(-1)) and hexachlorobenzene (HCB; 0.15-0.91 ng g(-1)). In sediments, the dominant OC were also DDTs (3.3-28 ng g(-1)) and PCBs (2.3-15 ng g(-1)). These concentrations are low, involving absence of major pollution sources in these high mountain regions. The downcore OC profiles in soils and sediments were similar but higher concentrations and steeper vertical gradients were observed in the latter. Radiometric determinations showed absence of significant OC transport from catchment to lake. The sediment-soil difference points therefore to a better retention of the OC load in sediments than soils which may be related to the low temperatures that are currently encountered at the bottom of the lake water column and the depletion of sediment bioturbation in these cold environments. Significant qualitative changes in the soil PCB distributions are observed downcore. These involve a dominance of the high molecular weight congeners in the top core sections and those of lower weight (i.e. less chlorinated) in the bottom. Anaerobic dechlorination of higher molecular weight congeners occurring in microsites, e.g. as observed in flooded or poorly drained soils, could be responsible for these changes. This process could be concurrent to bioturbation.
对欧洲两个高海拔山区湖泊(比利牛斯山脉的雷东湖和塔特拉山脉的拉多维湖)土壤和沉积物中持久性有机氯化合物(OC)的组成进行了研究。还对塔特拉山脉另外两个湖泊——旧莱什尼亚斯克湖和杜吉斯塔湖的沉积物岩芯进行了检测。土壤中最主要的有机氯化合物是滴滴涕(1.7 - 13纳克/克),其次是多氯联苯总量(PCBs;0.41 - 1.5纳克/克)和六氯苯(HCB;0.15 - 0.91纳克/克)。沉积物中占主导地位的有机氯化合物也是滴滴涕(3.3 - 28纳克/克)和多氯联苯(2.3 - 15纳克/克)。这些浓度较低,表明这些高山地区没有主要污染源。土壤和沉积物中沿岩芯深度的有机氯化合物分布情况相似,但后者的浓度更高,垂直梯度更陡。放射性测定表明,没有明显的有机氯化合物从集水区传输到湖泊。沉积物与土壤的差异表明,沉积物比土壤对有机氯化合物负荷的保留能力更强,这可能与当前湖底水柱的低温以及这些寒冷环境中沉积物生物扰动的减少有关。沿岩芯深度观察到土壤中多氯联苯分布存在显著的定性变化。这些变化包括岩芯上部高分子量同系物占主导,而底部则是低分子量(即氯含量较低)的同系物占主导。在微环境中发生的高分子量同系物的厌氧脱氯作用,例如在水淹或排水不良的土壤中观察到的情况,可能是造成这些变化的原因。这个过程可能与生物扰动同时发生。