Distribution and contamination status of chromium in surface sediments of northern Kaohsiung Harbor, Taiwan

Thedistribution, enrichment, accumulation, and potential ecological risk of chromium (Cr) in the surface sediments of northern Kaohsiung Harbor, Taiwan, Chinawere investigated. Sediment samples from ten locations located between the river mouths and harbor entrance of northern Kaohsiung Harborwere collected quarterly in 2011 and characterized for Cr, aluminum,water content, organic matter, total nitrogen, total phosphorous, total grease, and grain size. Results showed that the Cr concentrations varied from 27.0 to361.9 mg/kgwith an average of (113.5 ± 87.0) mg/kg. High Cr concentrationwas observed near the Jen-Gen River mouth. The mean Cr concentrationwas high at 255.5 mg/kg,whichwas at least 2 to 7 times than that of other sites. This might imply significant Cr contribution from upstream receiving tannerieswastewater into the Jen-Gen River. The spatialdistribution of Cr reveals relatively high in the river mouth region, especially in Jen-Gen River, and graduallydiminishes toward the harbor entrance region. This indicates that the major sources of Cr pollution from upstream industrial and municipalwastewatersdischarged along the river bank; and Cr maydriftwith sea current and bedispersed into open sea. Moreover, Cr concentrations correlated closely to the physical-chemical properties of the sediments,which suggested the influence of industrial and municipalwastewatersdischarged from the neighboring industrial parks and river basins. Results from the enrichment factor andgeo-accumulation index analyses imply that the Jen-Gen River sediments can be characterized as moderate enrichment and none to medium accumulation of Cr, respectively. However, results of potential ecological risk index indicate that the sediment has low ecological potential risk. The results can provide valuable information todeveloping future strategies for the management of river mouth and harbor.