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Environmental multi-media distributions and bioaccumulation characteristics of cyanobacterial toxins (microcystins) in the Geum River Estuary, Korea

Environmental multi-media distributions and bioaccumulation characteristics of cyanobacterial toxins (microcystins) in the Geum River Estuary, Korea
Other Titles
금강 하구역 내 담수 남조류 독소 마이크로시스틴의 환경 다매체 분포 및 생물농축 특성
Dokyun Kim
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남조류 기원 독성물질 마이크로시스틴(MCs)은 수 생태계 생물에게 간 독성 및 생물 축적을 일으키며 최근 수십 년 동안 국내외 담수환경에서 남조류 대 발생과 함께 높은 농도로 발견되었다. 담수 생태계에서 MCs에 대한 연구는 비교적 활발히 이루어져 왔지만, 강 하구를 통해 연안으로 흘러 나왔을 때의 거동에 대해서는 거의 알려지지 않았다. 따라서 본 연구의 목적은 남조류 독성물질 MCs가 해양 환경으로 유입되었을 때 I) 연안 생태계 내 환경 다매체 거동을 파악하고, II) 수 생태계 내 생물 축적 특성을 명확히 밝혀내며, III) 연안 생물 먹이 망 전이 여부를 알아보고자 함이다. 본격적인 연구에 앞서, 환경 다매체 시료에서 MCs 분석방법을 최적화 하기 위해 정도 보증 / 정도 관리 가 수행되었다. 2017년 6월과 7월 하구 둑 내 / 외측에서 표층 수, 부유물질, 표층 퇴적물 시료가 채집되었다. 연안 지역에서 어류, 이매패류, 복족류, 게류 및 다모류를 포함한 생물 시료 또한 채집되었다. 생물들의 주요 먹이원과 영양 단계를 파악하기 위해 EA-IRMS 와 GC-IRMS를 이용하여 생물 조직에서의 탄소, 질소 안정동위원소분석과 아미노산의 질소 안정동위원소 분석을 각각 수행하였다. 6월 하구 둑에서 해양으로 갈수록 용존 및 입자상 MCs 농도는 130 ng L-1에서
Microcystins (MCs) cause toxicity (e.g., hepatotoxicity) and bioaccumulation in aquatic organisms and have been found in great concentrations in freshwater environments along with cyanobacterial blooms in recent decades. Although most studies of MCs dynamics in freshwater ecosystems have been focused, fate of MCs entering the coastal environments through rivers is largely unknown. In this study, we performed the analysis in order i) to determine fate of MCs on environmental multi-media distributions in estuary
ii) to clarify bioaccumulation characteristics of MCs in aquatic ecosystem
and iii) to elucidate food web transfer of MCs when the cyanobacterial toxins are introduced into marine environment. Prior to the all study, QA / QC was performed to optimize the microcystin analysis method in an environmental multi-media samples. Surface water, suspended solid (SS), and sediments were collected from 7 stations (inside and outside of sea dike) in June and July 2017. Biological samples including fishes, bivalves, gastropod, crab, and polychaete were collected from the estuarine areas. Concentrations of MCs (MC-LR, -RR, and -YR) were measured in discharged water and marine multimedia samples using HPLC-MS/MS. In order to determine the main food source and trophic position of organisms, C and N stable isotope analysis in bulk tissue, and N stable isotope analysis in amino acid were conducted using EA-IRMS and GC-IRMS, respectively. From inner to outer estuary in June, concentrations of dissolved and particulate MCs gradually decreased from 130 ng L-1 to < DL and from 6 ng L-1 to < DL, respectively. On the other hand, dissolved MCs concentrations increased from 19 to 50 ng L-1 after freshwater discharge. Concentrations of MCs were delivered to the area near the sea dike in June when it was little rainfall, but spread far away at the time of large discharge after July heavy rainfall as mainly dissolved phase. Meanwhile, concentrations of MCs in marine organisms varied among species, ranging from 40 to 870 ng g-1 dw. Concentrations of MCs in biota tended to decrease with increasing TP, indicating that MCs seem to be biodilution in marine food web.
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