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首页> 外文期刊>Limnology >Response of denitrification rate associated with wetting and drying cycles in a littoral wetland area of Lake Biwa, Japan
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Response of denitrification rate associated with wetting and drying cycles in a littoral wetland area of Lake Biwa, Japan

机译：日本琵琶湖沿岸湿地地区反硝化率与干湿循环相关的响应

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摘要

To clarify the relationship between denitrification activity and dry–wet levels in the littoral wetland sediments of Lake Biwa, Japan, denitrification rates and their regulating parameters (degree of dryness, redox potential, nitrate concentration) were measured on different moisture sediments. Redox potential in sediments was higher in the exposed region in contact with atmosphere than the flooded region covered with water. The nitrate concentration in interstitial waters was undetectable in the flooded region. On the other hand, concentration in the exposed region increased with increase in the degree of sediment dryness. The denitrification rate ranged from 0.001 to 0.88 μg N cm−3 h−1 in the exposed region and increased with the increase in the degree of dryness. In the flooded region, on the other hand, no detectable rate (0.001 μg N cm−3 h−1) was observed. This indicates that the rates in the exposed region were mainly influenced by nitrate concentration in the interstitial waters accumulated by desiccation of sediments, whereas rates in the flooded region were strongly limited by no accumulation of nitrate in the anaerobic conditions. The potential denitrification rate, under the application condition of nitrate, ranged from 0.13 to 0.26 μg N cm−3 h−1 in the flooded region and from 0.77 to 1.5 μg N cm−3 h−1 in the exposed region. The potential rates in the flooded region had a tendency to be lower than those in the exposed region, implying that the number of denitrifying bacteria in the flooded region was low due to inactivation of aerobic respiration and denitrification in the denitrifying bacteria community. Kinetic parameters, maximum rate (V max) and half-saturation constant (K s) for denitrification were calculated on the experimental procedures of the wetting–drying cycles of sediments. Both parameters decreased by the wetting treatment and increased by the drying treatment. The fluctuation of V max values with wetting–drying cycles indicated that the number of denitrifying bacteria was influenced by aerobic respiration and denitrification in the denitrifying bacteria community similar to the potential rates, and denitrifying enzyme was induced by the nitrate supplied by nitrification accelerated through the drying process. On the other hand, the fluctuation of K s values implied that members of denitrifying bacteria were shifted to members of high nitrate affinity by wetting treatment and of low nitrate affinity by drying treatment.
机译：为了阐明日本琵琶湖沿岸湿地沉积物中反硝化活性与干湿水平之间的关系，对不同水分沉积物的反硝化率及其调节参数（干燥度，氧化还原电位，硝酸盐浓度）进行了测量。与大气接触的裸露区域中，沉积物中的氧化还原电势高于被水淹没的区域。在淹没区域无法检测到间隙水中的硝酸盐浓度。另一方面，随着沉积物干燥度的增加，暴露区域的浓度增加。暴露区域的反硝化率范围为<0.001至0.88μgN cm−3 h-1 ，并随干燥度的增加而增加。另一方面，在水淹区域未观察到检出率（<0.001μgN cm-3 h-1 ）。这表明裸露区域的速率主要受沉积物干燥所累积的间隙水中硝酸盐浓度的影响，而淹水区域的速率受厌氧条件下无硝酸盐累积的强烈限制。在硝酸盐的施用条件下，淹水区的潜在反硝化速率为0.13至0.26μgN cm−3 h-1 ，且为0.77至1.5μgN cm−3 > h-1 在暴露区域。淹水区的潜在比率趋于低于裸露区域，这表明由于需氧呼吸的失活和反硝化细菌群落中的反硝化作用，淹没区的反硝化细菌数量很低。根据沉积物的干湿循环实验程序，计算了反硝化的动力学参数，最大速率（V max ）和半饱和常数（K s ）。两种参数均通过润湿处理而降低，而通过干燥处理而提高。 V max 值随干湿循环的波动表明，反硝化细菌的数量受反硝化细菌群落中有氧呼吸和反硝化作用的影响，与潜在速率相似，而反硝化酶则是由硝酸盐提供的硝酸盐诱导的。在干燥过程中硝化作用加快。另一方面，K s值的波动表明，反硝化细菌的成员通过润湿处理转变为硝酸盐亲和力高的成员，而通过干燥处理转变为硝酸盐亲和力低的成员。

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