废黄河口盐沼土硫酸盐还原速率的研究

A study on sulfate reduction in salt marsh near the estuary of obsolete Huanghe Ri vel

本文报道了江苏省北部废黄河口滩面盐沼土中的硫酸盐还原速率。两年内,用同位素标记法测定了两块试验地的硫酸盐还原速率。结果表明,它们均有较高的还原速率。积分得大米草地和互花米草地年总还原值分别为77.75mol SO_4^(2-)·m^(-2)和110.3mol SO_4^(2-)·m^(-2)。硫酸盐还原速率高可能有3个原因:①米草地下部分向上层提供大量有机物;②SO_4^(2-)可由渗透潮水补充,不会因SO_4^(2-)亏损而影响还原率;③硫化物浓度保持在低于引起毒害的水平。硫酸盐还原主要终产物是FeS_2。FeS_2作为被还原的临时贮存库,其浓度有季节性变化。此外,还讨论了硫酸盐还原在有机碳矿化中的作用及在盐沼生态系统中能流的意义。

In this paper, sulfate reduction rate in salt marshes near the estuary of obsolete Huanghe River was reported. The rates were measured for 2 years (1980—1988) in salt marsh ve getated with two species of Spartina by isotopic label technique. Results indicated that the integrated annual rate is about 77.75mol SO_4^(2-)·m^(-2)·yr^(-1) in Spartina anglica peat and about 110.3mol SO_4^(2-)·m^(-2)·yr^(-1) in S. alterniflora peat. Sulfate reduction rates in these experimental fields are probaly higher for three reasons: 1) underground production of Spartina spp. provides a large annual amount of organic substrates over a depth of 20 cm; 2) sulfate is rapidly resuplied to the peat by infiltrating tidal water, so that sulfa te depletion never limits the rate of reduction; 3) sulfate concentration remains below to xic levels. FeS_2 is a main end product of sulfur reduction, while FeS is not. FeS_2 acts as a temporary store of reduced sulfur, changing with seasons in its cocentration. The important role of sulfate reduction in mineralizing organic carbon and the significance of energy flow in salt marsh ecosystem were discussed.