Development of water quality criteria for arsenic to protect aquatic life based on species sensitivity distribution.

Arsenic is a hazardous environmental pollutant widely distributed globally. Arsenic toxicity is well known and it is regulated by many countries in terms of managing water quality and protecting aquatic organisms. Unfortunately, water quality criterion (WQC) to protect aquatic organisms has not been introduced in Korea yet. Thus, it is of great importance and necessity to introduce WQC to protect aquatic organisms from arsenic, as WQC play a significant role in protecting aquatic ecosystems from pollutants. Therefore, the purpose of this study is to derive arsenic water quality criterion for aquatic life in Korea. Arsenic acute toxicity tests were performed with 10 Korean native aquatic species, which belong to 7 different taxonomic groups. Based on the results of acute toxicity test and additional toxicity data from literature, the species sensitivity distribution (SSD) method was used in ecological risk assessment. The arsenic concentration of 95% protection level for aquatic life was 0.229 mg L-1 in this study. An assessment factor 3 and a background concentration 0.0004 mg L-1 were applied to the concentration value in consideration of the uncertainty of the data and the amount of arsenic natural generation. Consequently, the WQC value derived for arsenic was found to be 0.077 mg L-1. These results will serve as reference values to establish water quality criterion for the protection of aquatic life in Korea.

Occurrence of microplastics in the Han River and riverine fish in South Korea.

Microplastic pollution has been paid attention due to the possibly global threat to human health and ecosystem in recent years. In this study, we investigated the distribution of microplastics in the Han River and its tributaries, South Korea, and in six species of inhabiting fish, namely carp (C. carpio), crucian carp (C. cuvieri), bluegill (L. macrochirus), bass (M. salmoides), catfish (S. asotus), and snakehead (C. argus). We found that the concentration of microplastics in the surface waters (0 m) was 0-42.9 particles/m3 (mean: 7.0 ± 12.9 particles/m3) compared to 20.0-180.0 particles/m3 (mean: 102.0 ± 50.3 particles/m3) at a depth of 2 m. Concentrations in the river tributaries ranged from 1.2 to 234.5 particles/m3 (mean: 91.1 ± 72.3 particles/m3). The most common types the plastic identified were polyethylene (PE), silicone, and polystyrene, while polytetrafluoroethylene (PTFE), polyethylene, and polyester dominated in the tributaries. With respect to shape, >73% of the recovered microplastics were fragments and the rest were fibers in the water. We also measured the concentration of microplastics in the intestines of fish, which ranged from 4 to 48 particles/fish (mean: 22.0 ± 16.0 particles/fish). The most common types of plastic found in the sampled fish were polytetrafluoroethylene (PFTE), polyethylene (PE), and rayon, and >94% of all the microplastic found in fish was in the form of fragments with the remainder being fibers. The concentrations of microplastic in the gills of fish ranged from 1 to 16 particles/fish (mean: 8.3 ± 6.0 particles/fish). In contrast, no microplastic was found in the flesh of the sampled fish. Our results imply that the ingestion of microplastics by fish is more closely related to habitat rather than feeding habits.

Development of water quality criteria of ammonia for protecting aquatic life in freshwater using species sensitivity distribution method.

Ammonia is deemed one of the most important pollutants in the freshwater environment because of its highly toxic nature and ubiquity in surface water. This study thus aims to derive the criteria for ammonia in freshwater to protect aquatic life because there are no water quality criteria for ammonia in Korea. Short-term lethal tests were conducted to perform the species sensitivity distribution (SSD) method. This method is widely used in ecological risk assessment to determine the chemical concentrations to protect aquatic species. Based on the species sensitivity distribution method using Korean indigenous aquatic biota, the hazardous concentration for 5% of biological species (HC5) value calculated in this study was 44mg/L as total ammonia nitrogen (TAN). The value of the assessment factor was set at 2. Consequently, the criteria for ammonia were derived as 22mg/L at pH7 and 20°C. When the derived value was applied to the monitoring data nationwide, 0.51%, 0.09%, 0.18%, 0.20%, and 0.35% of the monitoring sites in Han River, Nakdong River, Geum River, Youngsan River, and lakes throughout the nation, respectively, exceeded this criteria. The Ministry of Environment in Korea has been considering introducing water quality standard of ammonia for protecting aquatic life. Therefore, our results can provide the basis for introducing the ammonia standard in Korea.