Organic carbon and reduced inorganic sulfur accumulation in subtropical saltmarsh sediments along a dynamic coast, Yancheng, China

Conversion mechanisms between organic sulfur and inorganic sulfur in surface sediments in coastal rivers

“…The values of AVS/CRS ratios, DOP and DOS are typically used to ascertain factors controlling the formation of AVS, CRS and the conversion of AVS to CRS (Gagnon et al, 1995). In this study, the AVS/CRS ratios in JL (mean 2.29 ± 0.17) and GD (mean 1.18 ± 0.08) were higher than 1, which were close to the ratios in adjacent coastal rivers in Laizhou Bay (mean 1.27, Sheng et al, 2015) and saltmarsh wetlands (mean 1) along coast of the North Yellow Sea (Yang et al, 2020), indicating low conversion from AVS to CRS occurred in study area. This notion was confirmed by low DOP and high DOS values in JL (DOP, 0.13 ± 0.02; DOS, 0.68 ± 0.05) and GD (DOP, 0.39 ± 0.03; DOS, 1.34 ± 0.13).…”

“…The low TOC (0.25 ± 0.01%) and high DO (7.9 ± 0.02 mg/L) and ORP (259.5 ± 0.01 mV) in JL (Table S1) suggested that the top layers of surface sediment were aerobic; these conditions would inhibit sulfate reduction and enhance S\ \Fe oxidation (Brocławik et al, 2020;Yang et al, 2020). This finding was consistent with low RIS retention fractions in JL (15.2% of total S).…”

“…AVS and CRS are two major end products of RIS in coastal sediments (Kraal et al, 2013;Sheng et al, 2015;Sun et al, 2016). The transformation from AVS to CRS is typically controlled by the OM, reactivity of Fe minerals and the availability of dissolved sulfate buried in sediments (Morgan et al, 2012;Yang et al, 2020), which can be identified by the AVS/CRS ratios, the degree of pyritization (DOP) and sulfurization (DOS).…”

Coupling mechanisms of S–Fe–P in surface sediments under the stresses of high salinity and heavy metals in coastal rivers

“…S2 f) in JH. This might suggest that the availabilities of TOC and ES played important roles in controlling CRS formation in JH (Zhu et al 2012;Yang et al 2020). Such relationships could also be attributed to the transformations of AVS and ES, which accelerate pyritization and increase RFe availability (Oueslati et al 2018;Łukawska-Matuszewska et al 2019).…”

“…3 since the sulfate-reducing reaction at lower pH was less efficient due to the accumulation of hydrogen ions, which inhibited the formation of polysulfide (Eqs. 5 and 6) (Yang et al 2020). Temporary aerobic conditions followed the inflow of highly saline surface water from the salt fields on both sides, thereby enhancing the oxidation of RFe and H 2 S (Latour et al 2018;Zhao et al 2019).…”