A Simple in situ Extraction Method for Dissolved Sulfide in Sandy Mud Sediments Followed by Spectrophotometric Determination and Its Application to the Bottom Sediment at the Northeast of Ariake Bay

Abstract

We developed a simple in situ extraction method for dissolved sulfide (H2S, HS−, S2−) in sandy mud sediments. All analytical procedures were performed in a sealed system of glass syringes to prevent the volatilization of hydrogen sulfide and the oxidation of sulfide by air. An adequate amount of sandy mud sediment was put in a graduated glass syringe on site immediately after sampling. This procedure was performed using a unique and useful tool ; a plastic syringe had its front portion cut, so as to avoid the attachment of sediment to the inside wall of the syringe. To the sediment sample in the syringe, distilled water, deoxygenated by babbling with nitrogen gas, was injected via a three-way stopcock with another syringe. After mixing well, the sample was filtrated into the other syringe through a filter (0.45 μm). In addition, zinc acetate solution was added to the filtrate in the syringe, and was then spectrophotometrically determined by the methyleneblue method after being brought back to laboratory. The proposed method was successfully applied to bottom sediment samples taken from northeast of Ariake Bay. A high concentration of dissolved sulfide was detected in a warmer season. This method should be useful to evaluate sediment quality and to assess the influence of dissolved sulfide on benthos such as bivalves.