A Field Experiment of Sulfide Reduction in Silty Sediment Using Steel-making Slag

摘要

Hydrogen sulfide is often generated through sulfate reduction under anaerobic conditions in enclosed coastal seas. It is highly toxic, depletes oxygen and forms blue tides. To evaluate the sulfide reduction effect of steel-making slag, we conducted field experiments in Fukuyama inner harbor, where people have suffered from odors caused by gasses including hydrogen sulfide generated from the sediments. We placed steel-making slag on the sediments, and monitored the quality of interstitial water in the sediments and the overlying water. Hydrogen sulfide gas was also collected and measured. Dissolved sulfides in the interstitial water of the steel-making slag construction area were suppressed to below 5 mg/L (as sulfur), while levels ranged from 100 to 350 mg/L in control plots; this reduction lasted for about 2 years. It was assumed that Fe ions eluted from steel-making slag may have reacted with the sulfide. Species number and individual numbers of macrobenthos increased in the steel-making slag construction area. The results imply that capping deteriorated sediments with steel-making slag can effectively improve water and sediment quality of coastal areas.