Sulfur Speciation in the Surface Sediments of Lakes from Different Regions, China: Characterization by S K-Edge XANES Spectroscopy

Abstract EN

X-ray absorption near edge structure (XANES) spectroscopy affords the opportunity to determine redox status for element S in the aquatic ecosystems.

However, there have been relatively few studies of S XANES spectroscopy in the terrestrial aquatic ecosystems.

In this study, XANES technology was used to examine changes in S speciation in the sediments collected from Taihu Lake, Qinghai Lake, Dianchi Lake, Caohai Lake, and Hongfeng Lake located in distinct geological background areas of China.

The results showed that sedimentary S in Qinghai Lake has a high proportion of sulfate averaged 88.9% due to physical weathering of watershed rocks, while deposited S in Taihu Lake has a high fraction of intermediate S (36.5%), which may be the response of the agricultural nonpoint source pollution in drainage basin.

The three lakes located in Southwest China have similar composition characteristics of S species, indicating similar S sources including chemical weathering of carbonate and atmospheric deposition.

60–90% of S compounds in the surface sediments were in the form of sulfate and FeS.

In deeper layers, the ratio of FeS2 and the intermediate S significantly increased, suggesting rapid processes of sulfate reduction and sulfide reoxidation with the increasing depths.