낙동강 Microcystis aeruginosa 군체에 부착생활하는 미세조류 2종

신재기 ( Shin Jae-ki ),박용은 ( Park Youngeun ),김영성 ( Kim Youngsung ),황순진 ( Hwang Soon-jin ) 한국물환경학회 2020 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2020 No.-

This study was carried out to determine the distribution of cyanobacterium Pseudoanabaena and epiphytic diatom populations in 13 weir pools in the Nakdong River during the summer of 2018 and 2019. The cyanobacterium Microcystis aggregates into colonies with a mucilaginous sheath that constitutes a special microhabitat for many microorganisms that associate to it. Here, we examine the notorious, yet scarcely studied case of epiphytic association by the cyanobacterium Pseudoanabaena spp. to colonial Microcystis aeruginosa (MA). In decades, Pseudoanabaena species have been frequently reported as cyanobacterial bloom components. However, these species are always overlooked because they cannot be observed easily owing to their small sizes. The observed species composition was P. limnetica and P. mucicola. The observation of Pseudoanabaena started from the upstream and the amount increased exponentially toward the downstream. Maximum density was 4.5×10⁶ cells/mL. The dynamics pattern of Pseudoanabaena was similar to that of Microcystis. In terms of their density, it could be attributed to sufficient potential sources of toxin and off-flavour (especially 2-MIB) due to harmful cyanobacterial bloom in the Nakdong River. Furthermore, the cyanobacterial colonies were in turn colonized by the diatom species. This co-occurrence has been previously reported only fourth in the literature and this study will be the first in Korea. This diatom (identified as Nitzschia palea) had selectivity on MA and the phytoplankton biotic habitat of epiphyton was related to colony size and density. Field observation as well as a literature revision, suggest that the association of between the two types of organisms is symbiotic, assuring a continuous supply of nutrients of exogenous and endogenous origin. Besides obtaining nutrients, an epiphytic diatom also benefits from suspension in the upper part of the photic zone, where availability of light and nutrients is higher. The species was observed up to 2.0×10⁵ cells/mL only from Hapcheon-Changnyeong weir to the mouth barrages of Nakdong River, and during that time, the inorganic silicate was dramatically depleted. The epiphytic diatom observed this study could be recommended as an ecological pollutant species with Microcystis population colonies.

낙동강 Microcystis aeruginosa 군체에 부착생활하는 미세조류 2종

신재기 ( Shin Jae-ki ),박용은 ( Park Youngeun ),김영성 ( Kim Youngsung ),황순진 ( Hwang Soon-jin ) 한국물환경학회 2020 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2020 No.-

This study was carried out to determine the distribution of cyanobacterium Pseudoanabaena and epiphytic diatom populations in 13 weir pools in the Nakdong River during the summer of 2018 and 2019. The cyanobacterium Microcystis aggregates into colonies with a mucilaginous sheath that constitutes a special microhabitat for many microorganisms that associate to it. Here, we examine the notorious, yet scarcely studied case of epiphytic association by the cyanobacterium Pseudoanabaena spp. to colonial Microcystis aeruginosa (MA). In decades, Pseudoanabaena species have been frequently reported as cyanobacterial bloom components. However, these species are always overlooked because they cannot be observed easily owing to their small sizes. The observed species composition was P. limnetica and P. mucicola. The observation of Pseudoanabaena started from the upstream and the amount increased exponentially toward the downstream. Maximum density was 4.5×10⁶ cells/mL. The dynamics pattern of Pseudoanabaena was similar to that of Microcystis. In terms of their density, it could be attributed to sufficient potential sources of toxin and off-flavour (especially 2-MIB) due to harmful cyanobacterial bloom in the Nakdong River. Furthermore, the cyanobacterial colonies were in turn colonized by the diatom species. This co-occurrence has been previously reported only fourth in the literature and this study will be the first in Korea. This diatom (identified as Nitzschia palea) had selectivity on MA and the phytoplankton biotic habitat of epiphyton was related to colony size and density. Field observation as well as a literature revision, suggest that the association of between the two types of organisms is symbiotic, assuring a continuous supply of nutrients of exogenous and endogenous origin. Besides obtaining nutrients, an epiphytic diatom also benefits from suspension in the upper part of the photic zone, where availability of light and nutrients is higher. The species was observed up to 2.0×10⁵ cells/mL only from Hapcheon-Changnyeong weir to the mouth barrages of Nakdong River, and during that time, the inorganic silicate was dramatically depleted. The epiphytic diatom observed this study could be recommended as an ecological pollutant species with Microcystis population colonies.

낙동강 하구에서 플라스틱 배출특성 실시간 모니터링

신재기 ( Shin Jae-ki ),박용은 ( Park Youngeun ),김영성 ( Kim Youngsung ) 한국물환경학회 2020 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2020 No.-

Land-based macroplastic across the river channels is considered one of the major sources of marine plastic debris. However, estimations of plastic emission from the rivers into the oceans remain scarce and uncertain, mainly due to a severe lack of standardized observations. To properly assess global plastic fluxes, detailed information on spatiotemporal variation in river plastic quantities and composition are urgently needed. We present a new methodology to characterize riverine macroplastic dynamics. The proposed methodology was applied to estimate the plastic emission from the Nakdong River, Korea. During the three typhoons (Lingling, Tapah and Mitag) impact periods of autumn 2019, real-time cross-sectional profiles of plastic transport were made across the river width. Simultaneously, sub-samples were taken to determine the composition, size, and weight of riverine macroplastics (>5 cm). Finally, extrapolation of the observations based on available hydrological data yielded estimates of daily, monthly and annual macroplastic emission into the ocean. Our results suggest that plastic emissions from the Nakdong River are the first estimates. Importantly, our flexible methodology can be adapted to local hydrological circumstances and data availability, thus enabling a consistent characterization of macroplastic dynamics in rivers worldwide. Such data will provide crucial knowledge for the optimization of future mediation and recycling efforts.

낙동강 하구에서 플라스틱 배출특성 실시간 모니터링

신재기 ( Shin Jae-ki ),박용은 ( Park Youngeun ),김영성 ( Kim Youngsung ) 한국물환경학회 2020 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2020 No.-

Land-based macroplastic across the river channels is considered one of the major sources of marine plastic debris. However, estimations of plastic emission from the rivers into the oceans remain scarce and uncertain, mainly due to a severe lack of standardized observations. To properly assess global plastic fluxes, detailed information on spatiotemporal variation in river plastic quantities and composition are urgently needed. We present a new methodology to characterize riverine macroplastic dynamics. The proposed methodology was applied to estimate the plastic emission from the Nakdong River, Korea. During the three typhoons (Lingling, Tapah and Mitag) impact periods of autumn 2019, real-time cross-sectional profiles of plastic transport were made across the river width. Simultaneously, sub-samples were taken to determine the composition, size, and weight of riverine macroplastics (>5 cm). Finally, extrapolation of the observations based on available hydrological data yielded estimates of daily, monthly and annual macroplastic emission into the ocean. Our results suggest that plastic emissions from the Nakdong River are the first estimates. Importantly, our flexible methodology can be adapted to local hydrological circumstances and data availability, thus enabling a consistent characterization of macroplastic dynamics in rivers worldwide. Such data will provide crucial knowledge for the optimization of future mediation and recycling efforts.

내성천 상류 수생태계의 인공 부영양화에 대한 육수학적 고찰

신재기 ( Shin Jae-ki ),박용은 ( Park Youngeun ),김영성 ( Kim Youngsung ) 한국물환경학회 2020 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2020 No.-

내성천은 낙동강의 중상류로 유입되는 지류로서 전형적인 사질 기반 수생태계를 이루고 있다. 유역의 구조로 볼 때 상하류에서 소도시(봉화, 영주 및 예천)지역의 생활하수와 축산분뇨 처리수가 연중 배수되는 유일한 통로에 해당하여 부영양화에 대한 근본적인 취약성을 가지고 있다. 그러나 이러한 문제점이 모래 하상과 자연 유수 환경에 의해 그동안 잘 드러나지 않았다. 기존 지천의 농업용 보에 더하여 본류에 댐이 추가되면서 그 구간에는 고수온기를 중심으로 유해남조의 극성 현상이 장기화 되어 사회적 이슈가 되었다. 본 연구는 내성천에서 야기되고 있는 유해남조의 번성을 이해하기 위하여 2019년 9월, 12월 및 2020년 4월에 내성천 상류 약 40 km구간에서 하도 특성, 기초 수질 및 藻類 생물량을 중심으로 수행하였다. 조사지점은 내성천 4개, 낙화암천 1개 및 토일천 1개로서 총 6개이었다. 내성천 지점은 봉화읍 하류를 기점으로 낙화암천 합류 전 후 각 1개 및 유사조절지댐과 영주댐 직하류 각 1개이었고, 2개 지류는 하구에서 조사하였다. 주요 항목의 실험분석은 표준법(APHA, 2018)으로 하였다. 생물학적 수질의 총체적 결과를 나타내는 Chlorophyll-a 농도 중 식물플랑크톤은 상류(< 10 mg/㎥)에서 하류( >20 mg/㎥)로 갈수록 점진적으로 증가하였고, 부착조류는 시공간적으로 부영양 수준(>10 μg/㎠)을 초과하였다. 미세조류 생물량을 비교할 때, 하천 내의 증가량에 대해 주의 깊게 관찰해야함을 암시하였다. 본 연구는 단기 조사이긴 하지만 내성천에서 인간 활동이 하천 수질과 수생태계에 어떻게 영향을 미치는가를 확연하게 설명할 수 있었다. 그리고 하천의 인위적 변형으로 생긴 잠재적 문제점은 현재에도 축적 심화되는 방향으로 진행 중이었으며, 그 내용을 육수학적 측면에서 고찰하였다.

저수지 수위 변동성과 유해 남조의 동태학적 비교

신재기 ( Shin Jae-ki ),이형근 ( Lee Hyung-kun ),박용은 ( Park Youngeun ),김영성 ( Kim Youngsung ) 한국물환경학회 2020 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2020 No.-

본 연구는 2019년 6월-2020년 1월 동안에 대청호의 본류(방아실, 회남대교) 및 소옥천만(환평리, 추소리)에서 유해남조의 발생특성과 그 영향을 비교하기 위해 수행되었다. 주요 대상항목은 수문(수위, 방류량 중심), 수온, chlorophyll-a (CHLA) 및 식물플랑크톤 종조성, 현존량 등 이었고, 현장조사는 강우패턴을 고려하여 월 1-2회 하였다. 최근 대청호의 수위는 과거에 비해 연중 높게 유지하는 상태이었다. 그래서 지류하천의 상류(전이대)는 예전과 달리 하상 바닥을 드러내지 않는 지형적 특성을 보여 부착조류 생태계의 규모가 급감하였다. 실시간 연속적으로 측정된 일 수온은 8월 초에 최고값을 나타냈다. 그 시기 이후에 본류에서 CHLA는 높아지기 시작하였으나, 지류에서는 조사기간 내내 폭발적인 수준을 나타내어 시공간적으로 확연히 다른 양상과 차이를 보였다. 식물플랑크톤 종조성 변화에서도 다소 상이하였다. 본류와 소옥천만에서 CHLA의 범위는 각각 2.2-278.4 mg/㎥ 및 7.1-52,333.8 mg/㎥으로서 변동성이 매우 컸다. 연구기간동안 CHLA의 증가는 본류에서 1회(9월) 관찰되었는데 수위가 높아지는 시기이었으나, 지류는 매우 복잡하였다. 저수지의 수위가 연중 높게 유지될 경우, 하류(댐)의 수질은 상류(본류)의 영향이 보다 큰 것으로 파악되었고, 지류는 고립되는 형태로 볼 수 있었다. 그러나 평상시 발전방류 이외 홍수시 여수로 방류조건이 주어진다면 그 양상은 다를 것으로 예상되었다. 특히 효과적인 물관리 측면에서 유해 남조가 대발생하는 과영양화된 수역은 이러한 상황을 연중 예의 주시해야 함을 암시하였다.