期刊论文详细信息
Aquatic Microbial Ecology
Effects of solar radiation on the utilization of dissolved organic matter (DOM) from two headwater streams
Susan Ziegler1  Sherri Brisco1 
关键词: Dissolved organic matter (DOM);    Ultraviolet radiation;    Streams;    Bioavailability;   
DOI  :  10.3354/ame037197
学科分类:生物科学(综合)
来源: Inter-Research
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【 摘 要 】

ABSTRACT: The effect of solar radiation on dissolved organic matter (DOM) utilization was studied in 2 contrasting streams in Arkansas, USA, from June 2002 through July 2003. Moores Creek is an agricultural stream with elevated nutrient and dissolvedorganic carbon (DOC) concentrations. Huey Hollow is a forest stream with low nutrient and DOC concentrations. A series of in situ experiments were conducted seasonally in both streams to assess how exposure of DOM to solar radiation impacted itsutilization, measured as bacterial production following exposure and subsequent inoculation with whole stream water. Exposure of DOM to solar radiation significantly decreased its utilization during most seasons in both streams. Both streams experiencedone period when exposure of DOM significantly increased bacterial production; during these periods, DOM appeared to be the least bioavailable and most photochemically reactive. In spring, ultraviolet absorption coefficients, normalized to DOCconcentration, suggested a greater proportion of photoreactive DOM in Huey Hollow. Additionally the δ13C signature of DOM (δ13CDOM) suggested the largest terrestrial input occurred in spring whenexposure of DOM significantly increased bacterial production. Both the proportion of photoreactive DOM and δ13CDOM exhibited little seasonal variation in Moores Creek; however, the relative bioavailability of DOM did vary,suggesting some change in DOM composition. In spring the relative bioavailability of DOM was lowest in Moores Creek, and DOM exposure appeared to have further reduced its bioavailability. Elevated ammonium concentrations at this time suggestphotochemically enhanced humification may be an important mechanism influencing DOM cycling, and warrants study in streams impacted by agricultural land use.

【 授权许可】

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