School of Geography, South China Normal University, Guangzhou, 510631, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
Environ Sci Pollut Res Int. 2019 Aug;26(22):22472-22484. doi: 10.1007/s11356-019-05536-w. Epub 2019 Jun 3.
During the past few decades, the Yangtze River basin has undergone massive anthropogenic change. In order to evaluate the impacts of human interventions on sediment n-alkanes of lakes across this region, the aliphatic hydrocarbon fractions of 19 surface sediment samples collected from lakes along the middle reaches of the Yangtze River (MYR) were analyzed using gas chromatography-mass spectrometry. The n-alkanes extracted from the sediments contained a homologous series from C15 to C34, with a notable predominance of odd carbon compounds except for sediments from the more intensively industrialized Lake Daye, in which > C21 n-alkanes showed no odd/even predominance, and carbon preference index (CPI) approached unity. Abundance values of middle-chain (C21, C23, and C25) and long-chain (C27, C29, C31, and C33) n-alkanes in Lake Daye were approximately 4 to 3 times greater than the average for other lakes, reaching 272.4 and 486.3 μg/g TOC, respectively, in the study. Short-chain n-alkanes (C15, C17, and C19) in the sediments varied in abundance from 10.0 to 76.2 μg/g TOC across the study and showed a moderate correlation with total phosphorus (TP) concentrations in the overlying water. The results indicated anthropogenic eutrophication enhanced the accumulation of short-chain n-alkanes in sediments because the primary producers in which they are synthesized are highly susceptible to nutrient forcing. Middle-chain n-alkane abundances were less affected by eutrophication and generally enriched in macrophyte lakes, while long-chain n-alkanes tend to be low in sediments from more eutrophic water. In the case of Lake Daye, direct discharges of petroleum products from heavy industry have introduced quantities of petroleum n-alkanes (> C21), far exceeding the amounts of biogenic input, and the sediment > C21 n-alkanes detected in this study showed typical characteristics of petroleum source. In other lakes, inputs of petroleum products from surface runoff of vehicle/traffic emissions associated with urbanization and economic growth contributed comparatively few n-alkanes to sediments, resulting in declines in CPI for > C21 n-alkanes, most obviously in Lakes Huanggai, Donghu, and Futou. Calculated CPI values suggest that a major proportion of the n-alkanes present in these lakes are derived from biogenic input. The results of this study provided evidences that n-alkane profiles of lake sediments respond sensitively to human-induced eutrophication and different sources of petroleum pollution.
在过去的几十年中，长江流域发生了大规模的人为变化。为了评估人类干预对该地区湖泊沉积物正构烷烃的影响，使用气相色谱-质谱法分析了取自长江中游（MYR）沿线湖泊的 19 个表层沉积物样本的脂肪族烃馏分。从沉积物中提取的正构烷烃包含 C15 到 C34 的同系物系列，除了更工业化的大冶湖的沉积物外，除了沉积物外，大多数都是奇数碳化合物，其中> C21 正构烷烃没有奇数/偶数优势，并且碳优势指数（CPI）接近 1。大冶湖沉积物中中链（C21、C23 和 C25）和长链（C27、C29、C31 和 C33）正构烷烃的丰度值大约是其他湖泊平均值的 4 到 3 倍，分别达到 272.4 和 486.3μg/g TOC。研究中，沉积物中的短链正构烷烃（C15、C17 和 C19）的丰度从 10.0 到 76.2μg/g TOC 不等，与上覆水中的总磷（TP）浓度呈中度相关。结果表明，人为富营养化增强了沉积物中短链正构烷烃的积累，因为它们合成的初级生产者极易受到养分的影响。中链正构烷烃丰度受富营养化的影响较小，通常在大型植物湖中富集，而长链正构烷烃在更富营养化的水中的沉积物中含量较低。就大冶湖而言，重工业的石油产品直接排放带来了大量的石油正构烷烃（> C21），远远超过了生物输入的数量，本研究中检测到的沉积物> C21 正构烷烃显示出石油源的典型特征。在其他湖泊中，城市化和经济增长带来的地表径流和交通排放物中的石油产品输入对沉积物的正构烷烃输入相对较少，导致> C21 正构烷烃的 CPI 下降，在黄盖湖、东湖和浮头湖最为明显。计算出的 CPI 值表明，这些湖泊中存在的大部分正构烷烃均来自生物输入。本研究的结果提供了证据，表明湖泊沉积物中正构烷烃分布对人为富营养化和不同来源的石油污染非常敏感。
