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Temporal variation in riverine organic carbon concentrations and fluxes in two contrasting estuary systems: Geum and Seomjin, South Korea

Title
Temporal variation in riverine organic carbon concentrations and fluxes in two contrasting estuary systems: Geum and Seomjin, South Korea
Author
신경훈
Keywords
Estuary dam; Riverine organic carbon; Geum River; Seomjin River
Issue Date
2019-12
Publisher
PERGAMON-ELSEVIER SCIENCE LTD
Citation
ENVIRONMENT INTERNATIONAL, v. 133, Article no. 105126
Abstract
In this study, surface water samples were collected at sites located in the lowest reaches of closed (Geum) (i.e. with an estuary dam at the river mouth) and open (Seomjin) estuary systems between May 2016 and May 2018. We analyzed concentrations and stable isotopes of particulate organic carbon (POC) and dissolved organic carbon (DOC) to assess OC sources, to estimate fluxes of riverine OC, and to assess some of the factors driving OC exports in these two contrasting Korean estuary systems. Our geochemical results suggest that the contribution of the phytoplankton-derived POC to the total POC pool was larger in the Geum River than in the Seomjin River. Notably, a heavy riverine algae bloom occurred in the Geum River in August 2016, resulting in a high carbon isotopic composition (-19.4%) together with low POC/PN ratio (˂ 10) and POC/Chl-a ratio (˂ 100). In contrast, potential DOC sources in both the Geum River and the Seomjin River were a mixture of C3-derived forest soils and cropland organic matter. During the study period, the catchment area-normalized fluxes of POC and DOC were 0.40x10(-3) tC/km(2)/yr and 6.5x10(-2) tC/km(2)/yr in the Geum River and 5.2x10(-4) tC/km(2)/yr and 8.6x10(-4) tC/km(2)/yr in the Seomjin River, respectively. It appears that the POC flux was more weakly associated with the water discharge in the Geum River than in the Seomjin River, but the DOC fluxes were in general controlled by the water discharges in both rivers. Accordingly, the estuary dam of the Geum River might be one of the most strongly influencing factors on seasonal patterns in POC fluxes into the adjacent coastal seas, strongly modifying water residence times and thus biogeochemical processes.
URI
https://www.sciencedirect.com/science/article/pii/S0160412019318811http://repository.hanyang.ac.kr/handle/20.500.11754/122265
ISSN
0160-4120; 1873-6750
DOI
10.1016/j.envint.2019.105126
Appears in Collections:
COLLEGE OF SCIENCE AND CONVERGENCE TECHNOLOGY[E](과학기술융합대학) > MARINE SCIENCE AND CONVERGENCE ENGINEERING(해양융합공학과) > Articles
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