Search Results (30)

Rural sustainability planning requires spatially explicit methods that integrate agricultural resource bases, ecological condition, low-carbon feasibility, community implementation support, and cultural landscape values. Although the Circular and Ecological Sphere (CES) concept offers an integrative framework for rural transition, empirical CES studies remain largely qualitative or policy-oriented. This study develops a FarmMap-integrated Python-GIS workflow for proxy-based CES-oriented spatial prioritization in Yangpyeong-gun, a peri-rural county on the eastern fringe of the Seoul metropolitan region in Korea. Public spatial and administrative datasets were integrated into thirteen indicators grouped under five CES-relevant axes. The model does not measure realized circular material flows, governance quality, resident participation, or carbon emission reduction directly; instead, it identifies where CES-relevant spatial potentials co-occur. An axis-balanced entropy model assigned equal total weight to each axis while applying entropy weighting within axes. Robustness was tested through equal-weight, axis-emphasis, raw entropy diagnostic, Monte Carlo perturbation, and spatial-scale sensitivity analyses using 100 m diagnostic, 500 m, and eup/myeon supports. The final 250 m priority surface identified the top fifth of analyzed Yangpyeong-gun area as very-high relative priority and remained stable across weighting and spatial-support diagnostics. Rural-experience villages and village enterprises had significantly higher CES scores than random background locations. The results demonstrate a reproducible first-stage spatial screening workflow for CES-oriented rural planning while clarifying the limits of proxy-based circularity, governance, and low-carbon indicators. Full article

Climate change has increased the frequency and intensity of extreme weather events worldwide. In South Korea, annual precipitation in 2014–2015 was only 50% of the long-term average, resulting in severe drought conditions. This drought extended water residence time in dam reservoirs, enhancing internal nutrient recycling, degrading water quality, and promoting harmful cyanophyta blooms in downstream reservoirs. Using the Standardized Precipitation Index—for drought assessment, and monthly water sampling—for environmental factors and phytoplankton analyses, this study examined the impacts of drought on water quality and phytoplankton communities in a series of interconnected dam reservoirs (Uiam, Cheongpyeong, Sambong-ri, and Paldang Lakes) within the Bukhan River system from 2013 to 2016. The prolonged residence time during drought facilitated nutrient accumulation and recycling within the reservoirs, intensifying eutrophication and water quality deterioration, alongside a pronounced cyanobacterial dominance and harmful algal blooms. These findings suggest that changes in upstream dam discharges directly influence water quality and ecosystem health in downstream reservoirs and that diverse hydrological changes associated with drought pose a significant threat to water source management. These findings may inform the development of integrated water management strategies for maintaining water quality and protecting water sources during droughts and extreme climatic events. Full article

This study aimed to determine the seasonal variations in the growth and species composition of phytoplankton in Lake Paldang, South Korea’s largest freshwater body, based on environmental factors. Weekly surface water samples were collected and analyzed for three years (2015–2017). A total of 160 species of phytoplankton were distributed across eight divisions. Diatoms were dominant in all seasons except summer and their seasonal equivalents. All seven indices—Shannon, equitability, Simpson, Menhinick, evenness, dominance, and Berger-Parker—presented a clear trend in September, which may be attributed to rainfall in July. Canonical correspondence analysis (CCA) was employed to analyze the relationship between the occurrence and the abundance of phytoplankton species and environmental factors. The results showed that WTE, TP, PO₄-P, and rainfall were negatively correlated with Ulnaria acus, Asterionella formosa, and Stephanodiscus hantzschii, whereas Scenedesmus sp. and Merismopedia tenuissima presented positive correlations. Microcystis demonstrated positive correlations with TOC, NH₃-N, and HRT, and appeared primarily in the summer and fall of 2015, a dry season. According to the Palmer pollution index, which is calculated based on phytoplankton species, Lake Paldang showed no signs of pollution for the top 99.8% of phytoplankton species, but was evaluated as organically polluted for overall phytoplankton, especially in spring and summer. Full article

Background/Objectives: The spread of antibiotic resistance, particularly through Enterococcus spp., in wastewater treatment plants (WWTPs) poses significant public health risks. Given that research on antibiotic-resistant enterococci and their antibiotic-resistance genes in aquatic environments is limited, we evaluated the role of Enterococcus spp. in WWTPs by comparing the antibiotic resistance rates, gene prevalence, biofilm formation, and residual antibiotics in the influent and effluent using culture-based methods. Methods: In 2022, influent and effluent samples were collected from 11 WWTPs in South Korea. Overall, 804 Enterococcus strains were isolated, and their resistance to 16 antibiotics was assessed using the microdilution method. Results: High resistance to tetracycline, ciprofloxacin, kanamycin, and erythromycin was observed. However, no significant differences in the overall resistance rates and biofilm formation were observed between the influent and effluent. Rates of resistance to ampicillin, ciprofloxacin, and gentamicin, as well as the prevalence of the tetM and qnrS genes, increased in the effluent, whereas resistance rates to chloramphenicol, florfenicol, erythromycin, and tylosin tartrate, along with the prevalence of the optrA gene, decreased. E. faecium, E. hirae, and E. faecalis were the dominant species, with E. faecalis exhibiting the highest resistance. Conclusions: Our results suggest that WWTPs do not effectively reduce the rates of resistant Enterococcus spp., indicating the need for continuous monitoring and improvement of the treatment process to mitigate the environmental release of antibiotic-resistant bacteria. Full article

We evaluated the thermal and chemical stratifications of Paldang Lake using Schmidt’s stability index (SSI) and the chemical stratification index (IC-i) with weekly data from 2013 to 2022. The temporal trends of stratification were analyzed alongside correlations with meteorological, hydrological, and water quality variables. Thermal stratification intensified with rising air temperature and sunshine duration, while hydrological factors like discharge and retention time affected SSI during periods with less than five days of water retention. During summer, fewer occurrences of intense rainfall or early rainfall before August led to stronger stratification. In fall, nutrient influx from external sources during summer stimulated algal growth, increasing Chlorophyll-α (Chl-α) concentrations. Summer rainfall had a significant impact on the strength and duration of stratification in Paldang Lake. Annual rainfall patterns and subsequent changes in discharge were key factors affecting the physical environment of the lake, which in turn determined water quality and the extent of algal blooms. We provide insights into the seasonal stratification and water quality variations in temperate river-type reservoirs like Paldang Lake. SSI and IC-i from this research can be applied to understand stratification and mixing dynamics in other lakes. Full article

Multidrug-resistant (MDR) Escherichia coli poses a significant threat to public health, contributing to elevated rates of morbidity, mortality, and economic burden. This study focused on investigating the antibiotic resistance profiles, resistance and virulence gene distributions, biofilm formation capabilities, and sequence types of E. coli strains resistant to six or more antibiotic classes. Among 918 strains isolated from 33 wastewater treatment plants (WWTPs), 53.6% (492/918) demonstrated resistance, 32.5% (298/918) were MDR, and over 8% (74/918) were resistant to six or more antibiotic classes, exhibiting complete resistance to ampicillin and over 90% to sulfisoxazole, nalidixic acid, and tetracycline. Key resistance genes identified included sul2, bla_TEM, tetA, strA, strB, and fimH as the predominant virulence genes linked to cell adhesion but limited biofilm formation; 69% showed no biofilm formation, and approximately 3% were strong producers. Antibiotic residue analysis detected ciprofloxacin, sulfamethoxazole, and trimethoprim in all 33 WWTPs. Multilocus sequence typing analysis identified 29 genotypes, predominantly ST131, ST1193, ST38, and ST69, as high-risk clones of extraintestinal pathogenic E. coli. This study provided a comprehensive analysis of antibiotic resistance in MDR E. coli isolated from WWTPs, emphasizing the need for ongoing surveillance and research to effectively manage antibiotic resistance. Full article

The Paldang Reservoir (PDR), the largest artificial lake in the Republic of Korea, has recently experienced increased chemical oxygen demand (COD), eutrophication, and algal blooms due to climate change. This study aimed to analyze the hydrological characteristics and water quality of the PDR and assess its spatial and seasonal eutrophication status changes using the Korean-type trophic quality index (TSI_KO) and the seasonal Mann–Kendall Test (SMK). The PDR’s water was graded “good” in terms of biochemical oxygen demand (BOD) and “fair” for COD, total phosphorous (TP), and chlorophyll-a (Chl-a), according to Korean water quality standards. COD and Chl-a had a significant positive monotonic relationship. According to the TSI_KO calculations, the trophic state of the PDR was mesotrophic, but eutrophic during the summer season. TSI_KO (Chl-a) in summer tended to increase with a slope value of 0.22 mg/m³/year. The main causes of eutrophication in the PDR were proposed to be TP and phytoplankton overgrowth. Therefore, lake and reservoir functions need to be assessed, and solutions that can effectively protect them from excessive eutrophication to ensure sustainable clean water use and protect freshwater ecosystems need to be found. Full article

Lake Uiam is situated midway through a basin with dams at both the upstream and downstream ends; considerable environmental fluctuations have been observed here. However, studies on changes in environmental factors and plankton community fluctuations remain limited. This study analyzed the seasonal physicochemical factors and changes in the phytoplankton community structure in Lake Uiam (2015–2016). Organic matter, phosphorus, total suspended solids (TSS), and Chl-a concentrations were high in the summer. Seasonal changes in the dominant taxa followed the typical succession pattern of temperate phytoplankton, with Bacillariophyceae (Ulnaria acus) being dominant in spring and Cyanophyceae (Pseudanabaena limnetica) dominant in summer. However, Cryptophyceae (Rhodomonas sp.) showed unusually high dominance in autumn. Cell abundance showed no seasonal differences. Rhodomonas sp. was negatively correlated with water temperature, suggesting its dominance in spring and autumn. Cryptophyceae showed a significant correlation with Chl-a (0.708 **), indicating its contribution to spring Chl-a concentrations. Cryptophyceae (Rhodomonas sp. and Cryptomonas spp.) commonly appear in spring but are dominant in autumn in Lake Uiam. Despite disturbances from various environmental factors, they showed higher adaptability than other algae, resulting in their consistent appearance and dominance, differing from the general succession patterns of temperate phytoplankton. Full article

Organic matter in lakes is categorized into allochthonous organic matter, such as leaves and sewage effluent, and autochthonous organic matter, generated by microorganisms within the water system. In this study, organic matter composition was analyzed using UV-vis spectroscopy and liquid chromatography-organic carbon detection (LC-OCD). Several allochthonous natural organic matter substances were collected including leaves, green leaves, forest soils, and paddy soils. The organic matter composition analysis in our study sites revealed that humic substances comprised the highest proportion (36.5–42.3%). Also, individual samples at each site exhibited distinct characteristics. This study used a humic substance-diagram (HS-diagram) and principal component analysis (PCA) to trace the sources affecting the river water quality and identify their origins. The humic substances of soil origin predominantly influenced the water quality, with the impact of organic matter significantly pronounced during the July rainfall period. Compared with the PCA results, the contribution of the humic substance (HS, 48.9%) and building block (BB, 42.0%) indices appeared higher between June and July in summer, likely due to non-degradable substances released by heavy rain. In fall, the contribution of low molecular weight neutrals increased from 71.2% to 85.2%, owing to a humic substance influx and decomposition. This study demonstrated the application of estimating the relative contributions of source materials in lakes utilized for drinking and agricultural water to identify sources, aiding in the development of efficient watershed management plans. Full article

The Paldang Reservoir (PDR) in South Korea is vital for supplying drinking water and maintaining ecosystems; thus, a comprehensive understanding of its water quality is necessary. Spatiotemporal changes in reservoir water quality were evaluated by applying Korean water quality indices and multivariate statistical techniques (MSTs). A dataset of 15 water quality parameters at five sites in the PDR were evaluated from 2017 to 2021. The organic matter, suspended matter, total phosphorus (TP), chlorophyll a (Chl-a), and total coliforms in the PDR exhibited a fair grade or higher. Chemical oxygen demand was found to correlate with biochemical oxygen demand, Chl-a, and TP. The average real-time water quality index (RTWQI) and average trophic state index (TSI_KO) of the PDR were excellent and mesotrophic, respectively, and 46% of eutrophic conditions occurred during the monsoon season. For a hierarchical cluster analysis (HCA), the five sites were grouped into three polluted areas and 12 months were grouped into dry and wet seasons. Principal component analysis and factor analysis identified four potential pollution sources (domestic sewage, industrial wastewater, intensive agricultural activities, and livestock wastewater) in the PDR and explained 79.7% of the total changes. Thus, the RTWQI, TSI_KO, and MSTs are useful tools for assessing freshwater quality in Korea, predicting potentially harmful conditions, and potentially assisting policymakers in PDR management. Full article

This study aimed to investigate the irrigation water quality, major pollution sources, and human health hazards by focusing on heavy metal concentrations in the surface water of the Han River watershed, South Korea that supplies water for consumption and irrigation. Here, Mn was found to have the highest mean concentration, with the maximum concentration recorded at IH-2. The heavy metal concentrations were higher during summer and fall than that during spring. The mean concentration of heavy metals was relatively high in the downtown area (1.8 times) and downstream of the wastewater treatment facilities (1.3 times), indicating that the wastewater treatment facilities (WTFs) may be the primary source of pollution. Water at most of the sites were found to be suitable for irrigation. However, the sodium absorption ratio and soluble sodium percentage indicated that IH-2 was unsuitable. The results of the principal component analysis indicated that anthropogenic (vehicle and industrial) activities were the primary sources of metal pollution. Ingestion was identified as the primary exposure pathway in terms of health risks. However, the hazard quotients and hazard index for all pathways were below the safety limit (<1) for children and adults. Full article

Given water pollution increases in aquatic ecosystems resulting from industrialization and rapid urbanization, appropriate treatment strategies to alleviate water pollution are crucial. The spatiotemporal distribution, sources, and potential risk of heavy metals and organic compounds were determined in surface water from the Han River watershed (n = 100) in wet and dry seasons. The inductively coupled plasma mass spectrometer (Cr and As), mercury analyzer (Hg), and ultra-high performance liquid chromatography tandem mass spectrometer (organic compounds) were used to analyze the target compounds. Total concentration and detection frequency were in the order: Cr (2.375 µg/L, 100%) > As (1.339 µg/L, 100%) > Hg (0.007 µg/L, 100%) for heavy metals, and carbofuran (0.051 µg/L, 75%) > bisphenol A (0.040 µg/L, 47%) > quinoline (0.020 µg/L, 32%) for organic compounds. The target compounds showed the highest concentration in the area near industrial facilities. High concentrations and risk levels of all target compounds, except quinoline, were observed during the wet season. Principal component analysis indicated anthropogenic activities were the primary source of pollution. Cr showed the most prominent environmental impact in the wet season, suggesting its ecological risk. Additional monitoring is required for clear risk pollutant assessments in aquatic ecosystems to aid policy implementation. Full article

To safeguard aquatic environments in and around the Han River watershed in South Korea, a multivariate statistical evaluation of trace elements, a trace element concentration analysis and source determination, and a human health risk assessment were conducted on 10 trace elements at 25 sites. The results demonstrated that the Han River watershed was mainly affected by anthropogenic activities (traffic/industrial activity). The range of concentrations was arranged in descending order: Fe (217.13 ± 301.03 µg/L) > Mn (102.36 ± 153.04 µg/L) > Zn (23.33 ± 79.63 µg/L) > Ba (29.05 ± 12.37 µg/L) > Ni (5.14 ± 11.57 µg/L) > Cu (3.80 ± 3.56 µg/L) > Pb (0.46 ± 0.52 µg/L) > Se (0.06 ± 0.04 µg/L) > Cd (0.01 ± 0.01 µg/L) > Ag (0.004 ± 0.013 µg/L). The hazard index values of trace elements in surface water for combined pathways (ingestion and dermal contact) were < 1.0 for both adults and children, indicating no possible human health hazards. The estimated total cancer risk did not exceed the acceptable limit (1 × 10⁻⁴) for adults and children. The findings of this study provide data-driven guidelines for water environment policy decisions in the study area. Full article

Reliable water quality monitoring data, identifying potential pollution sources, and quantifying the corresponding potential pollution source apportionment are essential for future water resource management and pollution control. Here, we collected water quality data from seven monitoring sites to identify spatiotemporal changes in surface water in the Imjin River Watershed (IRW), South Korea, distinguish potential pollution sources, and quantify the source apportionment from 2018–2020. An analysis was performed based on multivariate statistical techniques (MST) and the absolute principal component score-multiple linear regression (APCS-MLR) model. Statistically significant groups were created based on spatiotemporally similar physicochemical water quality characteristics and anthropogenic activities: low-pollution (LP) and high-pollution (HP) regions, and dry season (DS) and wet season (WS). There were statistically significant mean differences in water quality parameters between spatial clusters, rather than between temporal clusters. We identified four and three potential factors that could explain 80.75% and 71.99% in the LP and HP regions, respectively. Identification and quantitative evaluation of potential pollution sources using MST and the APCS-MLR model for the IRW may be useful for policymakers to improve the water quality of target watersheds and establish future management policies. Full article

This study evaluated the spatiotemporal variability of water quality in the Han River Basin (HRB) as well as the contributions of potential pollution sources using multivariate statistical and absolute principal component score-multiple linear regression (APCS-MLR) modeling techniques. From 2011 to 2020, data on water quality parameters were collected from 14 sites in the Ministry of Environment’s water quality monitoring network. Using spatiotemporal cluster analysis, these sites were classified into two periods over the year (dry and wet seasons) and into three regions: low pollution region (LPR), moderate pollution region (MPR), and high pollution region (HPR). Through principal component analysis, we identified four potential factors accounting for 80.1% and 74.1% of the total variance in the LPR and MPR, respectively, and three that accounted for 72.7% of the total variance in the HPR. APCS-MLR results indicated domestic sewage and phytoplankton growth (25%), domestic sewage and seasonal influence (29%), and point pollution sources caused by domestic sewage and industrial wastewater discharge (31%) as potential factors for the LPR, MPR, and HPR. These results demonstrate that the multivariate statistical techniques and the APCS-MLR model can be effectively used to monitor network design, quantitatively evaluate potential pollution sources, and establish efficient water quality management policies. Full article