Contamination of Zinc in Sediments at River Mouths and Channel in Northern Kaohsiung Harbor, Taiwan

Abstract

The distribution, enrichment, accumulation, and potential ecological risk of zinc (Zn) in sediments at river mouths and channel of northern Kaohsiung Harbor, Taiwan were investigated. Sediment samples from 12 locations of northern Kaohsiung Harbor were collected and characterized for Zn, aluminum, water content, organic matter, total nitrogen, total phosphorous, total grease and grain size. Results showed that the Zn concentrations varied from 75-2,537 mg/kg with an average of 590±677 mg/kg. The spatial distribution of Zn reveals that the Zn concentration is relatively high in the river mouth region, and gradually diminishes toward the harbor entrance region. This indicates that upstream industrial and municipal wastewater discharges along the river bank are major sources of Zn pollution. Results from the enrichment factor analyses imply that the sediments collected from the river mouth can be characterized between severe and very severe degree enrichment of Zn. However, results of potential ecological risk index indicate that the sediment has low ecological potential risk. River and Canon River are located in Kaohsiung City's northern, basin area of about 45% of the entire Kaohsiung City, and regions along river have dense population with prosperous business and industrial establishments. The major pollution source includes domestic wastewater discharges, industrial wastewater discharges (e.g. paint and dye, chemical production, metal processing, electronic and foundry), municipal surface runoff, and transportation pollution (2). All the pollutants will eventually be transported to the river mouth and/or harbor to deposit and accumulate in the bottom sediment. The objective of this study is to investigate the Zn distribution in the surface sediment at river mouths and channel of northern Kaohsiung Harbor, Taiwan so that the degree of Zn enrichment, accumulation, and potential ecological risk can be evaluated.