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Tracing nitrogen sources fueling coastal green tides off a volcanic island using radon and nitrogen isotopic tracers

Title
Tracing nitrogen sources fueling coastal green tides off a volcanic island using radon and nitrogen isotopic tracers
Author
신경훈
Keywords
Green tide; Eutrophication; Submarine groundwater discharge; Jeju Island; Nitrogen isotope; Radon
Issue Date
2019-05
Publisher
ELSEVIER SCIENCE BV
Citation
SCIENCE OF THE TOTAL ENVIRONMENT, v. 665, Page. 913-919
Abstract
The main sources of nutrients fueling coastal green tides off a volcanic island surrounded by an oligotrophic ocean are obscure, although they result in many societal and ecosystem problems. In this study, we attempted to trace the source inputs of nutrients in coastal waters off a volcanic island, Jeju, Korea, where the formation of green tides is perennial, using a radioisotope (Rn-222) and stable isotopes (delta N-15 and delta O-18) as tracers. Sampling of groundwater, seawater, fish-farm water, and Ulva spp. was performed during April and July 2015. The contribution of submarine fresh groundwater discharge (SFGD) to the dissolved inorganic nitrogen input was ˃70%, with additional inputs from aqua-cultural activities and bottom sediments. The delta N-15-NO3 and delta O-18-NO3 values in the coastal seawater and groundwater indicate that the main source of NO3- is fertilizer, rather than other potential sources, such as aquacultural wastewater, sewage/manure contamination, or precipitation, in this region. The delta N-15 value (+7.3-+7.7 parts per thousand) in Ulva spp. also indicates the same source. Thus, our results suggest that the rapid infiltration of land N-fertilizer and subsequent leakage into the coastal ocean through submarine groundwater discharge (SGD) results in green tide massive occurrence in coastal waters off a high-permeability volcanic island. (c) 2019 Elsevier B.V. All rights reserved.
URI
https://www.sciencedirect.com/science/article/pii/S0048969719307004https://repository.hanyang.ac.kr/handle/20.500.11754/121334
ISSN
0048-9697; 1879-1026
DOI
10.1016/j.scitotenv.2019.02.212
Appears in Collections:
COLLEGE OF SCIENCE AND CONVERGENCE TECHNOLOGY[E](과학기술융합대학) > MARINE SCIENCE AND CONVERGENCE ENGINEERING(해양융합공학과) > Articles
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