Driving forces underlying changes in carbon molecular component deposition in a river-lake ecotone. (March 2023)

• Record Type: Journal Article
• Authors: Tian, Jiaming; He, Xinghua; Wu, Hanzhi; Chen, Yan; Yu, Kangkang; Zhang, Mingli; Wang, Yanhua
• Is Part Of: Ecological indicators. Volume 147(2023)
• Publication Date: 2023-03
• Subjects: River-lake ecotone -- Poyang Lake -- Lipid biomarker -- Source apportionment -- Driving force; Environmental monitoring -- Periodicals; Environmental management -- Periodicals; Environmental impact analysis -- Periodicals; Environmental risk assessment -- Periodicals; Sustainable development -- Periodicals; 333.71405
• DOI: 10.1016/j.ecolind.2023.109976
• Languages: English
• ISSNs: 1470-160X

Abstract

Graphical abstract: Highlights: Anthropogenic-driven carbon burial in estuarine sediments limits GHG emission. 5–6 ring PAH deposition increased yearly, accounting for 66.48% of the total. Long-chain n -alkanes with an odd-even predominance peaked at n C31 . Rapid changes in fuel combustion and land surface drive sediment carbon sink. Abstract: Carbon molecular deposition in sediments removes organic carbon (OC) from the biosphere-atmosphere carbon cycle and therefore limits the emission of greenhouse gases (i.e. CH4 and CO2 ) from natural water systems. At present, the occurrence characteristics, deposition fluxes, and driving force of OC components in the river-lake ecotone are unclear. Here, the tempo-spatial distribution of polycyclic aromatic hydrocarbons (PAHs) and Σ n -alkanes ( n C13 – n C32 ) related to organic nitrogen (ON) and OC in the estuarine sediments from Poyang Lake and their sources and effects were investigated. The ON and OC contents in the sediment cores ranged from 0.35−0.64 % and 1.9–4.24 %, respectively, and the PAH fluxes varied between 672.19 and 24703.97 ng cm −2 a -1, showing an upward risk to the water bodies and human health. In particular, it is worth noting that the 5–6 ring monomers were dominant, accounting for 66.48 % of the ΣPAHs in the sediment profile. The sources were mainly derived from biomass combustion and automobile exhaust emissions, while the latter proportion has increased in recent decades. In the sediment profile, the n -alkane abundance peak was found at n C31 with a marked odd-even predominance. The deposition flux for Σ n -alkanes ranged between 10.92 and 73.46 μg cm −2 a -1 . In addition, long-chain monomers dominated the Σ n -alkanes and were found to be herbaceous in origin. An analysis of the environmental indicators in the sediment layers showed that forest restoration and the eutrophication of water bodies caused by anthropogenic stress and climate change were mainly responsible for the relatively large contribution made by vascular plants and autochthonous organisms.