Ren Jiao, Wang Xiaoping, Wang Chuanfei, Gong Ping, Wang Xiruo, Yao Tandong
Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China.
Environ Pollut. 2017 Jan;220(Pt A):636-643. doi: 10.1016/j.envpol.2016.10.019. Epub 2016 Oct 15.
Biomagnification of some persistent organic pollutants (POPs) has been found in marine and freshwater food chains; however, due to the relatively short food chains in high-altitude alpine lakes, whether trophic transfer would result in the biomagnification of POPs is not clear. The transfer of various POPs, including organochlorine pesticides and polychlorinated biphenyls (PCBs), along the aquatic food chain in Nam Co Lake (4700 m), in the central Tibetan Plateau, was studied. The POPs levels in the water, sediment and biota [plankton, invertebrates and fish (Gymnocypris namensis)] of Nam Co were generally low, with concentrations comparable to those reported for the remote Arctic. The composition profiles of POPs in the fish were different from that in the water, but similar to their food. DDEs, DDDs, PCB 138, 153 and 180 displayed significant positive correlations with trophic levels, with trophic magnification factors (TMFs) ranged between 1.5 and 4.2, implying these chemicals can undergo final biomagnification along food chain. A fugacity-based dynamic bioaccumulation model was applied to the fish with localized parameters, by which the simulated concentrations were comparable to the measured data. Modeling results showed that most compounds underwent net gill loss and net gut uptake; only when the net result of the combined gut and gill fluxes would be positive, bioaccumulation could eventually occur. The net accumulation flux increased with fish age, which was caused by the continuous increase of gut uptake by aged fish. Due to the oligotrophic condition, efficient food absorption is likely the key factor that influences the gut POPs uptake. Long residence times with half-lives up to two decades were found for the higher chlorinated PCBs in Gymnocypris namensis.
在海洋和淡水食物链中已发现某些持久性有机污染物（POPs）的生物放大作用；然而，由于高海拔高山湖泊中的食物链相对较短，营养转移是否会导致POPs的生物放大作用尚不清楚。本研究了包括有机氯农药和多氯联苯（PCBs）在内的各种POPs在青藏高原中部纳木错湖（4700米）水生食物链中的转移情况。纳木错湖的水、沉积物和生物群[浮游生物、无脊椎动物和鱼类（纳木错裸鲤）]中的POPs水平普遍较低，其浓度与偏远北极地区报告的浓度相当。鱼类中POPs的组成特征与水中不同，但与它们的食物相似。滴滴伊、滴滴滴、多氯联苯138、153和180与营养级呈显著正相关，营养放大因子（TMFs）在1.5至4.2之间，这意味着这些化学物质可沿食物链最终发生生物放大作用。将基于逸度的动态生物累积模型应用于具有局部参数的鱼类，模拟浓度与实测数据相当。建模结果表明，大多数化合物经历了鳃净损失和肠道净吸收；只有当肠道和鳃通量的综合净结果为正时，生物累积最终才会发生。净累积通量随鱼龄增加，这是由于老龄鱼肠道吸收的持续增加所致。由于贫营养条件，高效的食物吸收可能是影响肠道对POPs吸收的关键因素。在纳木错裸鲤中发现，较高氯代的多氯联苯具有长达二十年的长停留时间和半衰期。
