Abstract:
Objective The aim is to understand the speciation content and distribution characteristics of inorganic sulfur (S) in Dongping Lake Wetland.
Method Twenty soil surface samples (0 - 5 cm) were collected around Dongping Lake, and soil column samples (0 - 10 cm) were also collected in different seasons from vegetable areas (reed area, Potamogeton crispus area, mixed vegetation area and control area with no vegetation). The contents of inorganic S in different forms which according to the order of extraction are H2O-S (HS), Adsorbed-S (AS), HCl-Soluble-S (HSS) and HCl-Volatile-S (HVS) were analyzed. Furthermore, the spatial distribution characteristics and its influencing factors were discussed.
Result The results showed that the content of total inorganic S (TIS) in the surface soils of Dongping Lake Wetland ranged from 31.26 mg kg−1 to 117.36 mg kg−1 with the mean value of 75.85 mg kg−1, and the average proportions of the inorganic S speciation contents were in the order of HS (43.49%) > HSS (27.37%) > AS (26.78%) > HVS (2.36%). The spatial distribution of inorganic S speciation contents in surface soils showed that they were generally significantly higher near the wharves of the lake area but were lower at the entrance of the Dawen River. The contents of TIS, HS, AS and HSS in the columnar soils were significantly different in vegetation areas, depths and seasons. Specifically, the inorganic S speciation contents were the highest in summer and in reed area, and the contents decreased with the increase of depth. Nevertheless, the TIS, AS and HSS contents in the Potamogeton crispus area had no significant seasonal change due to the influence of the interaction effect. Some forms of inorganic S in the surface and columnar soils were significantly positively correlated with each other, and there were generally significant positive correlations between the inorganic S forms and organic matter. Besides, the inorganic S forms except HVS in columnar soils were also positively correlated with soil pH but negatively correlated with soil Eh.
Conclusion The spatial distribution of soil inorganic S in Dongping Lake wetland was mainly affected by human activities, vegetation distribution and hydrodynamic conditions; and soil organic matter, temperature, soil pH and Eh were the key influencing factors.