海洋碎屑小生境形成演化过程中营养盐特殊迁移过程及脱氢酶活性的变化

研究了海洋碎屑小生境形成、演化过程中营养盐特殊迁移过程和脱氢酶活性的变化。结果表明,在充氧水体中同时存在硝化和反硝化过程,并有高浓度No(?)富集。脱氢酶活性在实验第4天达到最高值,在第96天和192天出现波动。碎屑聚集体表面不但有微生物群落的演替,而且存在物理化学微环境的连续变化;当碎屑表面O_2被消耗而出现氧化还原电位梯度时,电子最终受体出现更替,非平衡过程发生改变,为适应这种改变,微生物群落重新调节新陈代谢,在分叉点附近,脱氢酶活性增大。

SPECIFIC NUTRIENT TRANSFORMATION PROCESSES AND CHANGE IN DEHYDROGENASE ACTIVITY DURING FORMATION AND EVOLUTION OF MARINE DETRITAL MICROZONE

Fragile and flocculent detrital aggregates in the sea known as marine snow are ubiquitous and abundant components of the sea environment, an important site of phytosynthesis and nutrient regeneration. Detrital microzones as unique microenvi-ronments in oceanic waters support biochemical properties distinct from the ambient (such as high metabolic activity), and play an important role in the flux of energy and matter. This investigation on the specific nutrient transformation processes and change in dehydrogenase activity during the formation and evolution of the detrital microzone revealed the simultaneous presence of the processes of nitrification, den-itrification, and accumulation of high concentration of NO2- in aerobic waters. Dehydrogenase activity (DHA) reached maxium on the 4th day and oscillation of DHA occurred around the 92nd and 192nd day. The paper pointed out that marine detritus surfaces not only support a succession of microbial communities but also undergo successional change in non-equilibrium processes. When organic compounds are oxidized and the resulting depletion of O2 leads to the formation of a redox gradient and a reduced microzone on the detritus surface, NO3-, SO42-, CO32- may serve as terminal electron acceptors of respiration in the reduced region during evolution of microzone. The redox gradient of the detrital microzone allows aerobic and anerobic processes to coexist in close proximity, indicating different terminal electron acceptors may distribute spatially in the detrital microzone. The detrital microzone permits specific nutrient transformation processes which may not prosper or even be inhibited in the ambient waters. In response to the change in the detrital microzone nonequilibrium processes microbial communities regulate metabolism. The DHA increases at the change in terminal acceptors. The mechanism maintaining the stability of the detrital microzone is also discussed.