Tomomi Iwamura

Screening analysis of hundreds of sediment pollutants and evaluation of their effects on benthic organisms in Dokai Bay, Japan

Dokai Bay in Kitakyushu, Japan, is polluted with complex mixtures of micro-pollutants originating from the extensive industry and urbanization. In order to evaluate effects of these micro-pollutants on benthic organisms in this almost completely enclosed bay, we screened for the occurrence of approximately 900 organic chemicals and heavy metals, and in addition quantified the density and biomass of benthic animals. For the chemical analysis, we used a newly developed comprehensive analytical method using an automated identification and quantification system with a GC-MS database. We detected 184 organic chemicals in the sediments. Since their concentrations, as well as those of metals, increased with proximity to the innermost part of the bay, their source seem to be factories and a sewage treatment plant located in this area. Confirming this, the identified pollutants in this area are characteristic of industrial chemicals and residues, as well as household chemicals, fecal matter and sewage effluent. Several polycyclic aromatic hydrocarbons (PAHs) and metals had concentrations higher than the effects range-median of the sediment quality guidelines of National Oceanic and Atmospheric Administration. The species richness and abundance of benthic animals were lowest in areas where concentrations of metals, PAHs and other organic pollutants were high, suggesting that these contaminants are having an adverse effect on benthic animals in the bay.