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研究报告

摘要：用¹⁵N同位素配对法对太湖流域江苏和上海境内主要河流沉积物的反硝化作用及其影响因素进行研究.结果表明,河流沉积物反硝化作用具有显著空间差异.25℃时, 河流总反硝化速率D_tot在0~4.03 mmol·m^-2·d^-1之间;10℃时, D_tot在0~2.27 mmol·m^-2·d^-1之间,平均值分别为0.79 mmol·m^-2·d^-1和0.26 mmol·m^-2·d^-1.相关性分析显示,沉积物的反硝化作用与沉积物氮含量和实验过程中的耗氧速率(SOD)呈显著相关关系(p<0.01).以总反硝化速率大小为依据将沉积物分成4组后的相关分析表明,反硝化速率与原位上覆水中的NO₃^--N含量之间亦存在显著的相关关系(p<0.05),预示着反硝化作用对水体氮负荷起到的氮汇作用.

Abstract：Using N-15 isotope pairing technology(IPT),the denitrification processes of sediments as well as the possible affecting factors from main inflow and outflow rivers of Lake Taihu in Jiangsu and Shanghai were studied. Statistically significant differences of river sediment denitrification processes were observed. The total denitrification rates(D_tot)of the river sediments were 0~4.03 mmol·m^-2·d^-1 and 0~2.27 mmol·m^-2·d^-1,with average of 0.79 mmol·m^-2·d^-1 and 0.26 mmol·m^-2·d^-1,in 25℃ and 10℃, respectively. Significant correlations were observed between denitrification rates and nitrogen contents,as well as SOD in sediments(p<0.01). Four groups,based on D_tot value,were divided and used to evaluate the potential affecting factors for D_tot. Correlation analysis showed that the different nitrogen forms(NO₃^--N) in river water,were correlated with the sediments denitrification rates(p<0.05). This implied the river sediment denitrification would play an important role on nitrogen removal in these rivers.