Correcting a major error in assessing organic carbon pollution in natural waters

Nianzhi Jiao, Jihua Liu, Bethanie Edwards, Zongqing Lv, Ruanhong Cai, Yongqin Liu, Xilin Xiao, Jianning Wang, Fanglue Jiao, Rui Wang, Xingyu Huang, Bixi Guo, Jia Sun, Rui Zhang, Yao Zhang, Kai Tang, Qiang Zheng, Farooq Azam, John Batt, Wei-Jun Cai, Chen He, Gerhard J Herndl, Paul Hill, David Hutchins, Julie LaRoche, Marlon Lewis, Hugh MacIntyre, Luca Polimene, Carol Robinson, Quan Shi, Curtis A Suttle, Helmuth Thomas, Douglas Wallace, Louis Legendre

Microbial degradation of dissolved organic carbon (DOC) in aquatic environments can cause oxygen depletion, water acidification, and CO2 emissions. These problems are caused by labile DOC (LDOC) and not refractory DOC (RDOC) that resists degradation and is thus a carbon sink. For nearly a century, chemical oxygen demand (COD) has been widely used for assessment of organic pollution in aquatic systems. Here, we show through a multicountry survey and experimental studies that COD is not an appropriate proxy of microbial degradability of organic matter because it oxidizes both LDOC and RDOC, and the latter contributes up to 90% of DOC in high-latitude forested areas. Hence, COD measurements do not provide appropriate scientific information on organic pollution in natural waters and can mislead environmental policies. We propose the replacement of the COD method with an optode-based biological oxygen demand method to accurately and efficiently assess organic pollution in natural aquatic environments.

Functional and Evolutionary Ecology
External organisation(s)
Xiamen University, Macquarie University, Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Institute Ruder Boskovic (RBI), University of Delaware, State Key Laboratory of Heavy Oil Processing, Jepson Herbarium and Department of Integrative Biology, Plymouth Marine Laboratory, University of East Anglia, Columbia University in the City of New York, Joint Laboratory for Ocean Research and Education at Dalhousie University, Shandong University and Xiamen University, Chinese Academy of Sciences (CAS), Louisiana State University, Université Paris VII - Paris-Diderot
Science Advances
Publication date
Peer reviewed
Austrian Fields of Science 2012
106021 Marine biology
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