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Human activities changed organic carbon transport in Chinese rivers during 2004-2018.

Authors :
Liu, Dong
Tian, Liqiao
Jiang, Xintong
Wu, Huawu
Yu, Shujie
Source :
Water Research. Aug2022, Vol. 222, pN.PAG-N.PAG. 1p.
Publication Year :
2022

Abstract

• OC transport variations in 41 rivers across China during 2004-2018 were studied. • Human activities were the main driving forces decreasing the riverine OC content. • Chinese rivers are losing their Asian features of low DOC/POC ratios. Rivers serve as regulators of global climate by releasing greenhouse gases, burying particulate carbon, and connecting different ecosystem carbon pools. However, long-term organic carbon (OC) transport features across different Asian rivers are not well known due to unavailable data. Based on routinely monitored environmental and hydrological data during 2004-2018, this study investigated the spatiotemporal variations in dissolved (DOC) and particulate OC (POC) transport across 41 rivers in China. Across different rivers, both DOC (1.35 – 16.8 mg/L) and POC (0.27 – 4.48 mg/L) concentrations covered wide ranges. The DOC content was high in the north and low in the south, with significantly higher (t test, p < 0.01) values for rivers north of 30°N (5.39 ± 3.66 mg/L vs. 2.39 ± 1.14 mg/L). Human activities greatly influenced the riverine DOC and POC distributions. The riverine ammonia nitrogen (NH+ 4-N) content was positively correlated with DOC (r = 0.81 and p < 0.01) and explained 85.59% of its spatial variation. High vegetation coverage had significant effects on decreasing the riverine POC content, with r = -0.55 and p < 0.05. During 2004-2018, water pollution prevention and control strategies decreased DOC concentrations in 60.98% of rivers; meanwhile, anthropogenic vegetation restoration and dam construction led to POC content decreases in 90.48% of rivers. Importantly, along with DOC and POC changes, increasing DOC/POC ratios were found in 90.48% of the rivers, with 42.86% being significant, which indicated that Chinese rivers are losing their Asian features of low DOC/POC ratios due to artificial disturbance. This study is significant for accurately quantifying greenhouse gas emissions, carbon burial, and OC export to estuaries by Chinese rivers. [Display omitted] [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00431354
Volume :
222
Database :
Academic Search Index
Journal :
Water Research
Publication Type :
Academic Journal
Accession number :
158671445
Full Text :
https://doi.org/10.1016/j.watres.2022.118872