Diagnostic Evaluation and Preparation of the Reference Information for River Restoration in South Korea.

We assessed the naturalness of rivers based on the riparian vegetation index throughout the national territory of South Korea as a preparatory process for restoration to improve the ecological quality of rivers. The riparian vegetation index was obtained by incorporating the diversity of species and community, vegetation profile, and ratios of the number of species and areas occupied by exotic, obligate upland, and annual plants. The evaluation was conducted based on both the riparian vegetation index and each vegetation component. The result of the evaluation based on the riparian vegetation index showed that more than 70% of the river reaches were graded as less than "moderate" and exotic and obligate upland plants were more common than endemic aquatic plants. The reaches recorded as "very good" and "good" grades were usually restricted around the upstream of the north and central-eastern parts, whereas reaches of the other areas showed "poor" naturalness (less than "moderate"). The vegetation components selected for the evaluation showed a significant correlation with each other as well as the riparian vegetation index. The degree of contribution of each vegetation component showed that the vegetation profile played the most significant role, followed by species diversity, community diversity, and the ratio of area occupied by annual plants. The riparian vegetation index revealed a significant correlation with the indices based on other taxa such as benthic invertebrates, periphytic algae, and fish, habitat conditions in the waterway, and water quality based on biochemical oxygen demand (BOD). The diagnostic evaluation results imply that most reaches need ecological restoration. The reference information was prepared by incorporating the vegetation condition with the highest score in each reach in the diagnostic evaluation. The river reach was divided into five reaches of upper and lower valley streams, upstream, midstream, and downstream. Information on the reference vegetation for restoration was prepared with the stand profile including both horizontal and vertical arrangements of riparian vegetation and species composition classified by the reach divided into five types. The levels of restoration were determined based on the diagnostic evaluation results. The lower the naturalness grade, the higher the level of restorative treatment was recommended.

Distribution Patterns of Odonate Assemblages in Relation to Environmental Variables in Streams of South Korea.

Odonata species are sensitive to environmental changes, particularly those caused by humans, and provide valuable ecosystem services as intermediate predators in food webs. We aimed: (i) to investigate the distribution patterns of Odonata in streams on a nationwide scale across South Korea; (ii) to evaluate the relationships between the distribution patterns of odonates and their environmental conditions; and (iii) to identify indicator species and the most significant environmental factors affecting their distributions. Samples were collected from 965 sampling sites in streams across South Korea. We also measured 34 environmental variables grouped into six categories: geography, meteorology, land use, substrate composition, hydrology, and physicochemistry. A total of 83 taxa belonging to 10 families of Odonata were recorded in the dataset. Among them, eight species displayed high abundances and incidences. Self-organizing map (SOM) classified sampling sites into seven clusters (A⁻G) which could be divided into two distinct groups (A⁻C and D⁻G) according to the similarities of their odonate assemblages. Clusters A⁻C were characterized by members of the suborder Anisoptera, whereas clusters D⁻G were characterized by the suborder Zygoptera. Non-metric multidimensional scaling (NMDS) identified forest (%), altitude, and cobble (%) in substrata as the most influential environmental factors determining odonate assemblage compositions. Our results emphasize the importance of habitat heterogeneity by demonstrating its effect on odonate assemblages.

Organotin compounds act as inhibitor of transcriptional activation with human estrogen receptor.

In aquatic invertebrates, particularly marine gastropods, organotin compounds induce irreversible sexual abnormality in females, which is termed imposex, at very low concentrations. Organotin compounds are agonists for nuclear receptors such as RXRs and PPARgamma. However, the imposex phenomenon has not been reported to act as an antagonist on estrogen receptors in other species, including vertebrates and invertebrates. In order to gain insights into the antagonistic activity of organotin compounds on estrogen receptors (ERs), we examined the inhibitive effect of these compounds on estradiol-dependent beta-galactosidase activity using the yeast two-hybrid detection system consisting of a combination of the human estrogen receptor (hERbeta) ligand-binding domain and the co-activator steroid receptor co-activator-1 (SRC1). Tributyltin-hydroxide (TBT-OH) and triphenyltin-chlorine (TPT-Cl) exhibited an inhibitive effect on E2-dependent transcriptional activity, similar to antagonistic chemicals such as 4-hydroxytamoxifen (OHT) or ICI 182,780, at a very low concentration of 10⁻¹4 M TBT or 10⁻¹° M TPT, respectively. The yeast growth and transcriptional activity with transcriptional factor GAL4 did not exhibit any effect at the tested concentration of TBT or TPT. Moreover, the yeast two-hybrid system using the interaction between p53 and the T antigen of SV40 large did not describe any effect at the tested concentration of OHT or ICI 182,780. However, the interaction between p53 and T antigen was inhibited at a TBT or TPT concentration of 10⁻9 M, respectively. These results indicate that TBT and TPT act as inhibitors of ER-dependent reporter gene transcriptional activation and of the interaction between hERbeta LBD and the co-activator SRC1 in the yeast two-hybrid system. Consequently, our data could partly explain the occurrence of organotin compound-induced imposex on the endocrine system of mammals, including humans.

Respiratory health effects among schoolchildren and their relationship to air pollutants in Korea.

The objective of this study is to investigate the relationship between five air pollutants (PM(10), SO(2), NO(2), O(3), CO) measured on the daily basis, and adverse health symptoms using epidemiological surveillance data. The generalized estimated equation (GEE) model, a logistic regression analysis model, was used to estimate the effects of air pollution on children's daily health symptoms, focusing on the morbidity including both respiratory and allergic symptoms in four different cities. Analysis of the effects of each pollutant on children's respiratory and allergic symptoms demonstrated that CO affected all symptoms in all the study areas. When the concentration of SO(2) and NO(2) was elevated, upper respiratory symptoms increased significantly. In contrast, when the concentration of O(3) rose, the symptoms decreased significantly. The relationship between measured concentrations and health symptoms was site-dependent for each pollutant.