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A comparison of n-alkane contents in sediments of five lakes from contrasting environments
Organic Geochemistry ( IF 2.6 ) Pub Date : 2020-01-01 , DOI: 10.1016/j.orggeochem.2019.103943 Yongdong Zhang , Jinlei Yu , Yaling Su , Yingxun Du , Zhengwen Liu
Organic Geochemistry ( IF 2.6 ) Pub Date : 2020-01-01 , DOI: 10.1016/j.orggeochem.2019.103943 Yongdong Zhang , Jinlei Yu , Yaling Su , Yingxun Du , Zhengwen Liu
Abstract In paleolimnology studies, the trajectories of n-alkane abundances and distributions in dated sediments are widely used indicators of changing environmental and ecological status in the overlying water over time. However, the factors contributing to the variable n-alkane profiles of lake systems are not yet fully understood. Here, a comparative study was conducted to examine natural and anthropogenic influences on the sediment n-alkane profiles of five representative lakes in China. Core samples from the deep oligo- mesotrophic lakes Fuxian and Lugu (FX-1 and LG-1 cores), the shallow eutrophic lakes Taibai and Changdang (TB-1 and CD-1 cores) and the alpine Lake Heihai (HH-1 core) were used. While there were striking differences in n-alkane abundances and distributions between the cores, the results suggested that the n-alkanes in all five studied lakes were derived mainly from biogenic sources, rather than from petroleum contamination. The short-chain ( C21 n-alkane profiles of different cores varied significantly. Abundances of long-chain n-alkanes (C29, C31 and C33) in HH-1 were approximately 3–7 times greater than in other cores. Coupled with the lowest Paq (average 0.29) values recorded in the study, this indicates a predominantly terrestrial plant origin for the >C21 n-alkanes, most likely the dense alpine meadow which surrounds the lake. In other cores, however, aquatic macrophytes appear to be more important contributors of the n-alkanes, a result that corresponds with the relatively low density of terrestrial plants in those catchments.
更新日期：2020-01-01
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