Presence of Nitrate-Accumulating Sulfur Bacteria and Their Influence on Nitrogen Cycling in a Shallow Coastal Marine Sediment
Presence of Nitrate-Accumulating Sulfur Bacteria and Their Influence on Nitrogen Cycling in a Shallow Coastal Marine Sediment
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浅海沿岸海洋沉积物中积累硝酸盐的硫细菌的存在及其对氮循环的影响
DOI：
10.1128/aem.67.8.3481-3487.2001
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发表时间：
2001
影响因子：
4.4
通讯作者：
Mikio Sayama
中科院分区：
文献类型：
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作者：
Mikio Sayama
摘要对日本东京湾最深处沉积物-水之间的硝态氮通量、沉积物-水界面硝态氮浓度剖面以及原位沉积物反硝化活性进行了季节性测定。为了测定沉积物硝酸盐浓度，将未受扰动的沉积物岩心切成5 mm深的间隔，并将每段在−30°C下冷冻储存。测定冷冻和解冻沉淀物后上清液的硝酸盐浓度。表层沉积物中硝酸盐含量具有明显的季节性变化，在10月份达到最高值，可达400 μM。从界面浓度梯度预测的硝酸盐扩散通量的方向是全年的沉积物。相反，全柱培养法测得的总硝态氮通量的方向在所有季节都是进入沉积物。这种方向之间的矛盾表明，从冻结的表层沉积物中提取的硝酸盐池的很大一部分是不是孔隙水成分，和初步的检查表明，硝酸盐被包含在细胞内的空泡的丝状硫细菌居住或在表层沉积物。基于原位沉积物反硝化活性和总硝态氮通量的比较，认为细胞内硝态氮不能被沉积物反硝化直接利用，细胞内硝态氮的可能命运被推测为异化还原为铵态氮。因此，硝酸盐积累硫细菌的存在可能会降低自然界的自我净化能力（脱氮），并加剧浅水沿海海洋环境的富营养化。
ABSTRACT Nitrate flux between sediment and water, nitrate concentration profile at the sediment-water interface, and in situ sediment denitrification activity were measured seasonally at the innermost part of Tokyo Bay, Japan. For the determination of sediment nitrate concentration, undisturbed sediment cores were sectioned into 5-mm depth intervals and each segment was stored frozen at −30°C. The nitrate concentration was determined for the supernatants after centrifuging the frozen and thawed sediments. Nitrate in the uppermost sediment showed a remarkable seasonal change, and its seasonal maximum of up to 400 μM was found in October. The directions of the diffusive nitrate fluxes predicted from the interfacial concentration gradients were out of the sediment throughout the year. In contrast, the directions of the total nitrate fluxes measured by the whole-core incubation were into the sediment at all seasons. This contradiction between directions indicates that a large part of the nitrate pool extracted from the frozen surface sediments is not a pore water constituent, and preliminary examinations demonstrated that the nitrate was contained in the intracellular vacuoles of filamentous sulfur bacteria dwelling on or in the surface sediment. Based on the comparison between in situ sediment denitrification activity and total nitrate flux, it is suggested that intracellular nitrate cannot be directly utilized by sediment denitrification, and the probable fate of the intracellular nitrate is hypothesized to be dissimilatory reduction to ammonium. The presence of nitrate-accumulating sulfur bacteria therefore may lower nature's self-purification capacity (denitrification) and exacerbate eutrophication in shallow coastal marine environments.