The Yeongsan River is one of the four major rivers in South Korea. Since the construction of two weirs as part of the Four Major Rivers Project to secure water resources in 2011, issues with algal blooms have frequently arisen, prompting the Ministry of Environment of Korea to conduct continuous monitoring of water quality and algal outbreaks. This study, conducted between 2019 and 2023, examined the relationship between the phytoplankton community structure and physicochemical factors at the Seungchon and Juksan weirs. Phytoplankton were categorized into four groups (Bacillariophyceae, Chlorophyceae, Cyanophyceae, and other phytoplankton), and 20 dominant genera were selected for analysis. As microalgal species vary depending on environmental conditions, understanding the specific relationships among the microalgae observed in the study area can help explain their occurrence mechanisms and contribute to the development of effective management strategies. Therefore, we used principal component analysis (PCA) to analyze the seasonal variation patterns of the four microalgal groups and visualize key data features through dimensionality reduction. Additionally, PCA was employed to identify and visualize environmental factors related to seasonal variations in phytoplankton communities. PCA helped elucidate how different environmental factors influence phytoplankton fluctuations across seasons. We used canonical correspondence analysis (CCA) to investigate the relationships among the 20 dominant genera in each group and environmental factors. Additionally, CCA was used to analyze the relationship between the distribution of the top five dominant phytoplankton taxa in each group and various environmental factors. CCA allowed for a detailed examination of how these dominant taxa interact with environmental conditions. PCA revealed significant correlations between other phytoplankton and Chl-a in spring and Cyanophyceae and water temperature in summer. Bacillariophyceae was positively correlated with nitrogen-based nutrients but negatively with phosphate phosphorus (PO₄-P). CCA revealed significant correlations between dominant genera and environmental factors. Stephanodiscus sp. was associated with nitrogen-based nutrients, whereas Microcystis sp. and Dolichospermum sp. were associated with water temperature and PO₄-P. Stephanodiscus sp. affected water treatment through filtration and sedimentation issues, whereas Microcystis sp. and Dolichospermum sp. produced the toxin microcystin. These findings offer valuable insights for water quality management.

During the coronavirus disease 2019 (COVID-19) pandemic, 24,289 tons of infectious waste was generated in 2021 in Korea, a 320% increase compared to that generated in 2020 (5788 tons). The disposal of other healthcare waste has been delayed because COVID-19 infectious waste must be disposed of first, leading to long-term concerns related to the lack of healthcare waste disposal capacity. To solve this problem, this study investigated healthcare waste classification systems in Korea and overseas. We analyzed the current state of healthcare waste in Korea and compared the treatment methods and healthcare waste treatment systems by country. The results showed that Korea has a strict healthcare waste management system compared to other countries, which relies on dedicated incinerators and transport. It is difficult to expand incinerators exclusively for healthcare waste due to site selection issues because they incinerate infectious waste. Therefore, to solve the healthcare waste disposal problem, Korea should improve its management system to reduce treatment amounts. This study suggests that general healthcare waste that is considered less infectious should be excluded from healthcare waste-exclusive treatment and that sterilization/grinding as an intermediate treatment method should be allowed.