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首页> 外文期刊>Journal of great lakes research >Enhancement of Dissolved Organic Matter Bioavailability by Sunlight and Its Role in the Carbon Cycle of Lakes Superior and Michigan
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Enhancement of Dissolved Organic Matter Bioavailability by Sunlight and Its Role in the Carbon Cycle of Lakes Superior and Michigan

机译：阳光增强溶解有机物生物利用度及其在苏必利尔湖和密歇根州碳循环中的作用

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The degree to which sunlight and microbes interact in the cycling of dissolved organic matter (DOM) of natural waters is unclear. During 1999 and 2000, the effects of sunlight on the lability of DOM in two of the Laurentian Great Lakes were examined. Bacteria-free (< 0.2 μm) water samples collected in Lake Superior and Lake Michigan were exposed to ambient sunlight for several days and subsequently inoculated (1:10) with < 1.0 μm lake water containing natural bacteria and assayed for bacterial growth rates (~3H-leucine incorporation into protein) in the dark. Exposure of water collected from offshore surface layers to sunlight caused a net reduction of DOM bioavailability (bacterial growth ～20 to 30% of dark control), whereas both exposure of deep water and river water to sunlight resulted in a net enhancement of DOM bioavailability (bacterial growth ～150 to 260% of dark control). Irradiated water from nearshore exhibited an intermediate response in terms of changes in DOM bioavailability (bacterial growth ～75 to 115% of dark control). Despite the reduction of DOM bioavailability in surface waters by sunlight exposure in the short-term (relative to dark control), subsequent incubation of these waters in the dark increased bacterial production rates relative to in situ rates, suggesting that the net effect of exposure to sunlight, even in surface waters, was to increase DOM bioavailability. Rapid and sustained photochemical alterations of DOM bioavailability occurring in the euphotic zone of natural waters should accelerate the turnover of surface water, older deep water, and refractory terrigenous carbon.
机译：目前尚不清楚阳光和微生物在天然水的溶解有机物（DOM）循环中相互作用的程度。在1999年和2000年期间，研究了日光对两个Laurentian大湖中DOM的不稳定性的影响。将在苏必利尔湖和密歇根湖中收集的无细菌（<0.2μm）水样品暴露于环境日光下数天，然后用<1.0μm含天然细菌的湖水接种（1:10），并测定细菌生长速率（〜 3H-亮氨酸掺入蛋白质）在黑暗中。从近海表层收集的水暴露在阳光下会导致DOM生物利用度的净降低（细菌生长约为暗害控制的20％至30％），而深水和河水暴露在阳光下都会导致DOM生物利用度的净提高（细菌的生长〜黑暗控制的150％至260％）。从DOM的生物利用度变化来看，近岸辐射水表现出中等响应（细菌生长约为暗害控制的75％至115％）。尽管短期内（相对于黑暗控制）日光暴露会降低地表水中DOM的生物利用度，但随后在黑暗中进行这些水的孵育相对于原位速率而言却增加了细菌的产生速率，这表明暴露于水中的净效应即使在地表水中，阳光也可以增加DOM的生物利用度。在自然水的富营养区发生的DOM生物利用度的快速而持续的光化学变化将加速地表水，较旧的深水和难处理的陆源碳的周转。

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