With increasing anthropogenic activities, rivers and streams have become vulnerable to pollution; therefore, monitoring potential contaminants and the pollution status of surface sediments is essential. This study analyzed the concentrations of organic matter, metals, and metalloids; indices for organic, metal, and metalloid pollution; and ecological risk in river and stream sediments at 82 stations across Korea in 2017, 2018, and 2020. We performed bootstrapped analysis of variance, principal component analysis, and cluster analysis and used a structural equation model (SEM) to investigate spatiotemporal changes in the pollution status, main pollutant chemicals, and the exogenous factors affecting pollution status. The results suggest no significant differences in any of the twelve single chemical parameters and three pollution indices across the surveyed years. Metals, metalloids (Cu, Zn, Pb, and Hg), and organic matter with nutrients were identified as the main pollutants. The SEM demonstrated the significant influence of pollution sources—water used for industrial purposes, landfill wastewater discharge, and industrial wastewater discharge—on organic pollution, metal and metalloid pollution load, and environmental toxicity. This study identified consistently polluted areas, proposed additional management policies and stricter regulations on major point pollution sources rather than on broader land-use types, and suggested the combined consideration of metal toxicity risk with nutrient accumulation for future risk assessments. Supplementary Information The online version contains supplementary material available at 10.1007/s11356-023-27080-4.

Roadkill has been one of the most problematic issues with wildlife under urbanization. South Korea, one of the fastest industrializing countries in the world, has been affected by the same roadkill issues and has researched how to mitigate wildlife–vehicle collisions (WVCs). In the present study, we aimed to (i) review scientific studies concerning roadkill conducted in South Korea (51 domestic, 15 international papers, 19 reports, and 1 thesis), (ii) compare bibliographic networks between international and South Korean roadkill studies, and (iii) discuss future challenges. From a search in the core collection of Web of Science peer-reviewed papers published from 1992 to 2022, keywords were extracted to create a bibliometric visualization map, using VOSviewer. Among the 85 articles related to WVCs, those about eco-corridors have steadily increased since 1998, while mitigation system and roadkill articles have been published since the mid-2000s. With increased awareness, more systems have been established, and research related to WVCs has been increasingly established. Currently, there are two systematic roadkill monitoring systems in South Korea, and an increasing number of modeling studies have suggested where roadkill hotspots are located. How to mitigate roadkill incidents has also been explored. A comparison of associations between international and Korean research shows that the network structures of Korean society were more disconnected and less dispersed. In addition, the keywords were narrower than those used in studies from the international community. Although studies on landscape connectivity and road ecology are few, their number and scope in South Korea have increased and broadened. These studies could be more rapidly developed in the future as some systems are equipped.