Characteristics of River Sites with Elevated Concentrations of Linear Alkylbenzene Sulfonate: Implications for Water Environmental Management for Protection of Aquatic Life

Nationwide evaluation of the exceedance of environmental water quality standards （ EQS ） in the water environment plays a key role in establishing EQSs and effluent regulations. To understand the characteristics of river sites with annual mean concentrations of linear alkylbenzene sulfonate （ LAS ） that exceed the EQS, we compared （ 1 ） channel width as an indicator of river size, （ 2 ） surrounding land use, and （ 3 ） biochemical oxygen demand （ BOD ） as an indicator of organic pollution between “LAS-contaminated sites” with annual mean LAS concentrations of > 0.02 mg L -1 and “uncontaminated sites” with concentrations of ≤ 0.02 mg L -1 using water quality monitoring results from 2015-2016. Results indicated that, compared with uncontaminated sites, LAS-contaminated sites were found more frequently （ 1 ） in rivers with smaller and less variable channel width, （ 2 ） in rivers located in urban and residential areas with less forested and agricultural areas, and （ 3 ） in organic-polluted rivers indicated by higher annual mean of BOD. Generally, aquatic organisms in the natural environment are affected by many physicochemical factors including chemicals. Thus, as we demonstrated, the investigation of the physicochemical characteristics of water quality monitoring sites with higher concentrations of the chemicals of concern is valuable for evaluating management options that are substantially effective for protecting aquatic life.