Speciation Analysis Of Sulfur In Sediments And Its Applications

Sediment, as the accumulation library of matter migration and transformation, recorded the biogeochemical cycle of sulfur, having the buried information of sulfate reduction and sulfide formation, which would provide important information for global iron and carbon cycle, paleo-climate change and early diagenetic processes through research of sulfur cycle.This study discussed the influence of matrix effect on sulfur determination and compared different quantitative correction methods for the matrix effect, so as to establish a simple and fast method with effective sample pretreatment and accurate determination. At the same time, a sequential extraction method were established for sulfur speciation (H2O-S+A-S、AVW、HCl-S、S0、Spy、Sorg) in sediments using heat distillation method. Sulfur speciation in inner continental shelf in the East China Sea sediments were analyzed using sequential extraction method, this paper discussed the distribution of sulfur forms and sulfur isotope composition.The conclusions are as follows:1. A robust method for measuring sulfur content in sediments was established using double focusing inductively coupled plasma mass spectrometry at medium resolution combined with microwave digestion technique. The capability of Standard Curve Method (SCM) and Standard Addition Method (SAM) using Rh as internal standard was compared regarding correction of the matrix effect. The results showed that the matrix effect was not suppressed by SCM, but was effectively eliminated by SAM with drawback of low sample throughout. Therefore, the Standard addition calibration method (SACM) was creatively proposed in this study, which could simply and easily correct the matrix effect when the matrix content of sample and standard solution was matched within ±50%.2. A sequential extraction method was established for sulfur speciation (H2O-S +A-S、AVS、HCl-S、S0、Spy、Sorg)in sediments using self-made reaction device. To achieve best extraction efficiency and reproducibility, several parameters were selected and optimized systematically, including the extraction concentration and dosage, extraction temperature and time and others. Surface sediment samples were measured repetitively with spiked recovery of 94.1±2.3%, the accuracy was better than previous study.3. The established technique was applied to the analysis of sulfur content and isotopic composition distribution of various forms of the East China Sea continental shelf. Results showed that H2O-S+A-S and Spy were mainly dominant sulfur forms at site A and B, which account of 83.6% and 90.0% in overall proportion respectively, but the proportion of AVS and S0 were less than 2.0%. There may be a risk of biology toxicity of heavy metals at site A and B through the value of AVS/SEM and SEM-AVS evaluation. AVS:Spy ratio was far less than 0.3, reflecting the high conversion of AVS to pyrite. The sulfur isotope of 834SH2O-S+A-S(‰) was range of 12.13 ‰～18.92‰.The range of δ34SHCl-S (‰) was 2.41‰～16.43‰. However, the ratio of 834SAVS(‰),δ34Ss0(‰)、δ34Spy(‰),δ34Sorg(‰) were negative respectively, range from-13.09‰～-46.51%o. Meanwhile, the extent of variation of 834SAVS(‰), δ34Ss0(%o) and δ34Spy(‰) were consistent(first increase and then basically stable), which indicated Spy significantly controlled by AVS and S0.