Abstract：
Enhanced anthropogenic activity strength has altered the watershed particulate transport and material cycle resulting in organic pollutant deposition changes in Dongting Lake associated with unclear ecological risk. In the present study, dual biomarkers i.e. n-alkanes and polycyclic aromatic hydrocarbon (PAHs) were applied in the 210Pb-dated sediment cores for traceability of centennial organic pollutants in the lake mouth area. The partial least squares path model and risk quotients method were used to explore the controlling pathways and ecological risk. The results show a range of sedimentary organic carbon (C), nitrogen (N), and phosphorus (P) was at 1.76-185.66, 0.97-89.80, and 0.01-0.97 g m-2 yr-1 with total reserves of 51.68, 18.44, and 0.27 t ha-1, respectively, over the past 179 years. The presence of PAHs rapidly increased by 2.47 fold from 535.60 ng g-1, while PAHs and carcinogenic PAHs (ΣCPAHs) burial fluxes increased by about 6 and 5 folds, respectively. Accompanied by anthropogenic activities and climate change, the exotic sources gradually becoming predominant. The n-alkane diagnostic ratios indicated a shift of organic matter (OM) from autotrophic bacteria, algae, and phytoplankton-derived sources to macrophyte and terrestrial plants. The exotic origins rose to approximately 73.61 %, while endogenous sources decreased to 26.39 %. The direct effects of anthropogenic activities and their indirect negative impacts on climate and sedimentary structure are the key ways for sediment material loading. The nutrient accumulation in sediments coincides with the lake\'s eutrophication history over the past decades. The ΣCPAHs accounted for about 89.37 ± 17.14 % of the total TEQ, reflecting a strong ecological risk. The contribution of anthropogenic activities such as fuel usage, fertilizer application, hard pavement coverage, and OM loss from the ecosystem to the sources of organic pollutants and their component types may be a focus of attention in the middle reaches of the Yangtze River plain lake.
摘要：
人为活动强度的增强改变了流域颗粒物的迁移和物质循环，导致洞庭湖中有机污染物的沉积变化与不明确的生态风险有关。在本研究中,在210Pb年代的沉积物岩心中应用了双重生物标志物，即正烷烃和多环芳烃（PAHs），以追踪湖口地区的百年有机污染物。采用偏最小二乘路径模型和风险商方法探索控制路径和生态风险。结果表明，一系列沉积有机碳(C)，氮(N),磷（P）分别为1.76-185.66、0.97-89.80和0.01-0.97gm-2yr-1，总储量分别为51.68、18.44和0.27tha-1，在过去的179年中。PAHs的存在从535.60ngg-1迅速增加了2.47倍，而PAHs和致癌PAHs（ΣCPAHs）埋葬通量增加了约6倍和5倍，分别。伴随着人为活动和气候变化，外来资源逐渐成为主导。正构烷烃诊断比表明自养细菌中有机物（OM）的转移，藻类,以及浮游植物来源的大型植物和陆生植物。异国情调的起源上升到大约73.61％，而内源性来源下降到26.39%。人为活动的直接影响及其对气候和沉积结构的间接负面影响是沉积物物质负荷的关键途径。沉积物中的养分积累与湖泊过去几十年的富营养化历史相吻合。ΣCPAHs约占总TEQ的89.37±17.14%，反映了强烈的生态风险。人为活动的贡献，如燃料使用，施肥，硬路面覆盖,从生态系统到有机污染物来源的OM损失及其组分类型可能是长江中游平原湖泊关注的焦点。
