Large-river dominated black carbon flux and budget: A case study of the estuarine-inner shelf of East China Sea, China

Yin Fang; Yingjun Chen; Limin Hu; Chongguo Tian; Yongming Luo; Jun Li; Gan Zhang; Mei Zheng; Tian Lin

doi:10.1016/j.scitotenv.2018.10.156

Large-river dominated black carbon flux and budget: A case study of the estuarine-inner shelf of East China Sea, China

Sci Total Environ. 2019 Feb 15;651(Pt 2):2489-2496. doi: 10.1016/j.scitotenv.2018.10.156. Epub 2018 Oct 13.

Authors

Yin Fang¹, Yingjun Chen², Limin Hu³, Chongguo Tian⁴, Yongming Luo⁴, Jun Li⁵, Gan Zhang⁵, Mei Zheng⁶, Tian Lin⁷

Affiliations

¹ Key Laboratory of Cities' Mitigation and Adaptation to Climate Change in Shanghai, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
² Key Laboratory of Cities' Mitigation and Adaptation to Climate Change in Shanghai, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China. Electronic address: yjchentj@tongji.edu.cn.
³ Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China.
⁴ Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China.
⁵ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
⁶ SKL-ESPC and BIC-EAST, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
⁷ State Key Laboratory of Environmental Geochemistry, Guiyang Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China. Electronic address: lintian@vip.gyig.ac.cn.

PMID: 30336438
DOI: 10.1016/j.scitotenv.2018.10.156

Abstract

Mobilization of terrestrial-derived and recalcitrant black carbon (BC), including char and soot, from land to ocean exerts a significant influence on the global carbon cycle. This study elaborated the occurrence and spatial distributions of BC, char, and soot concentrations, as well as their burial fluxes, in the estuarine-inner shelf surface sediments of the East China Sea (ECS), an epicontinental sea adjacent to Chinese high-intensity BC emission source regions. Using a combination of BC measurements in the Yangtze River water and coastal ECS aerosol samples, a preliminary BC budget was concurrently constrained. The spatial distribution of char concentrations resembled largely that of BC, but differed significantly from that of soot, indicating that char and soot exhibited different geochemical behaviors. In contrast to concentrations, BC, char, and soot burial fluxes exhibited highly consistent spatial patterns, and all declined as the distance from the coastline increased. For the coastal ECS, riverine discharge dominated (~92%) the total BC input, with the Yangtze River alone accounting for as high as ~72%. The area-integrated sedimentary BC sink flux (630 ± 728 Gg/yr) in the coastal ECS was equivalent to the total BC influx (670 ± 153 Gg/yr), which coincided well with the regional sediment budget. This suggested that the terrestrial-derived and recalcitrant BC could be regarded as an alternative geochemical proxy for tracing the sediment source-to-sink processes in this region. Comparisons between BC and co-generated polycyclic aromatic hydrocarbons (PAHs) budgets in the coastal ECS revealed similarities in their input pathways, but dramatic differences in their ultimate fates. Despite these, the ECS estuarine-inner shelf could serve as a major sink of these terrestrial-based materials in the global ocean.

Keywords: Black carbon; Carbon cycle; East China Sea; Riverine discharge; Yangtze River.