TY - JOUR
T1 - How hydrology and anthropogenic activity influence the molecular composition and export of dissolved organic matter
T2 - Observations along a large river continuum
AU - Zhou, Yongqiang
AU - Yao, Xiaolong
AU - Zhou, Lei
AU - Zhao, Zhonghua
AU - Wang, Xiaolong
AU - Jang, Kyoung Soon
AU - Tian, Wei
AU - Zhang, Yunlin
AU - Podgorski, David C.
AU - Spencer, Robert G.M.
AU - Kothawala, Dolly N.
AU - Jeppesen, Erik
AU - Wu, Fengchang
N1 - Publisher Copyright:
© 2021 Association for the Sciences of Limnology and Oceanography
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/5
Y1 - 2021/5
N2 - Large rivers are the main arteries for transportation of carbon to the ocean; yet, how hydrology and anthropogenic disturbances may change the composition and export of dissolved organic matter along large river continuums is largely unknown. The Yangtze River has a watershed area of 1.80 × 106 km2. It originates from the Qinghai-Tibet Plateau and flows 6300 km eastward through the center of China. We collected samples (n = 271) along the river continuum and analyzed weekly samples at the most downstream situated gauging station in 2017–2018 and gathered long-term (2006–2018) water quality data. We found higher gross domestic product, population density, and urban and agricultural land use downstream than upstream of the Three Gorges Dam, coinciding with higher dissolved organic carbon (DOC), UV absorption (a254), specific ultraviolet absorbance (SUVA254), parallel factor analysis-derived C1–C5, aliphatic compounds, and lower a250:a365 and spectral slope (S275–295). Chemical oxygen demand, humic-like C1–C2 and C6, and protein-like C4 and C7 increased, while dissolved oxygen and ammonium decreased with increasing discharge at most of the sites studied, including the intensively monitored downstream site. The annual DOC fluxes were ca. 1.5–1.8 Tg yr−1, and 12–18% was biodegradable in a 28-d bio-incubation. Our results highlight that urbanization and stormwater periods enhanced the export of both terrestrial organic-rich substances and household effluents from nearshore residential areas. Our study emphasizes the continued need to protect the Yangtze River watershed as increased organic carbon loading or altered composition and bio-lability may change the ecosystem function and carbon cycling.
AB - Large rivers are the main arteries for transportation of carbon to the ocean; yet, how hydrology and anthropogenic disturbances may change the composition and export of dissolved organic matter along large river continuums is largely unknown. The Yangtze River has a watershed area of 1.80 × 106 km2. It originates from the Qinghai-Tibet Plateau and flows 6300 km eastward through the center of China. We collected samples (n = 271) along the river continuum and analyzed weekly samples at the most downstream situated gauging station in 2017–2018 and gathered long-term (2006–2018) water quality data. We found higher gross domestic product, population density, and urban and agricultural land use downstream than upstream of the Three Gorges Dam, coinciding with higher dissolved organic carbon (DOC), UV absorption (a254), specific ultraviolet absorbance (SUVA254), parallel factor analysis-derived C1–C5, aliphatic compounds, and lower a250:a365 and spectral slope (S275–295). Chemical oxygen demand, humic-like C1–C2 and C6, and protein-like C4 and C7 increased, while dissolved oxygen and ammonium decreased with increasing discharge at most of the sites studied, including the intensively monitored downstream site. The annual DOC fluxes were ca. 1.5–1.8 Tg yr−1, and 12–18% was biodegradable in a 28-d bio-incubation. Our results highlight that urbanization and stormwater periods enhanced the export of both terrestrial organic-rich substances and household effluents from nearshore residential areas. Our study emphasizes the continued need to protect the Yangtze River watershed as increased organic carbon loading or altered composition and bio-lability may change the ecosystem function and carbon cycling.
UR - http://www.scopus.com/inward/record.url?scp=85101050619&partnerID=8YFLogxK
U2 - 10.1002/lno.11716
DO - 10.1002/lno.11716
M3 - Journal article
AN - SCOPUS:85101050619
SN - 0024-3590
VL - 66
SP - 1730
EP - 1742
JO - Limnology and Oceanography
JF - Limnology and Oceanography
IS - 5
ER -