TOXICITY OF ELEMENTAL SULFUR IN SEDIMENTS

Elemental sulfur occurs naturally in marine and limnic sediments. Elem ental sulfur, brought in solution in aqueous media by using organic so lvents such as methanol as carrier solvent, was toxic in a bacterial l uminescence test, known as the Microtox test. Previously, it has been shown that the toxicity in the luminescence test of whole sediments al so was correlated to i.a. elemental sulfur using multivariate statisti cal analysis. Organic solvent extracts of sediments obtained in receiv ing waters of effluents from a pulp and paper mill was toxic in the lu minescence test, and using a toxicity evaluation procedure, the toxic substance was identified as octameric cyclic sulfur, S-8. The substanc e dominated the toxicity in extracts of both a contaminated sediment a nd a sediment from a control area. Since the toxicity in the Microtox test of aqueous solutions of S-8 decreased upon storage, a conversion process of the toxic form was indicated. Acute toxicity of S-8 was not limited to the luminescent bacteria in the Microtox test, but was obs erved in tests with fish larvae if tested with the transient form of e lemental sulfur. Tests of acute toxicity with zebra fish and perch lar vae were responsive to elemental sulfur. Probably, the toxic form of e lemental sulfur is the single cyclic octamer, that due to low aqueous solubility, binding to particulate sediment material or aggregation is converted into a nontoxic form. Acute toxic effects may occur in sulf ur containing sediments of varying,redox potentials or where elemental sulfur deposits are turbated. (C) 1998 by John Wiley & Sons, Inc. Env iron Toxicol Water Qual 13: 217-224,1998.