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首页> 外文期刊>Aquatic Microbial Ecology >Photochemical transformations of riverine dissolved organic matter: effects on estuarine bacterial metabolism and nutrient demand
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Photochemical transformations of riverine dissolved organic matter: effects on estuarine bacterial metabolism and nutrient demand

机译：河流溶解性有机物的光化学转化：对河口细菌代谢和营养需求的影响

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ABSTRACT: By experimentally simulating the exposure of terrigenous dissolved organic matter (DOM) to sunlight during the mixing of river water and seawater in an estuary (St. Helena Sound, South Carolina), this study examined how photochemical alterations may affect both the magnitude and fate of DOM utilization by estuarine bacteria. In a series of experiments performed with water samples collected from 3 blackwater rivers draining into an estuary of the South Atlantic Bight (USA), exposure to light resulted in significant decreases in dissolved organic carbon (DOC) concentration and DOM absorption at 350 nm relative to dark controls. When these water samples were subsequently inoculated with an estuarine bacterial community, prior exposure to light significantly increased bacterial growth, respiration and total DOC consumption relative to that observed in control treatments. Increases in respiration (46 to 78%) were, however, always greater than increases in growth (19 to 35%). This resulted in decreases in bacterial growth efficiency that ranged from 16 to 33% and appeared predictable from initial differences in DOM optical characteristics. In addition, although light exposure consistently resulted in significant NH4 production, bacterial metabolism in light treatments was accompanied by a significant increase in bacterial demand for inorganic nutrients (117 to 243% over dark controls). These results indicate that irradiation of terrigenous DOM significantly alters its ultimate fate (CO2 vs. bacterial biomass) and that bacterial carbon metabolism of photoaltered DOM is coupled to an enhanced demand for inorganic nutrients, which may considerably influence ecosystem-scale carbon and nutrient interactions in the coastal zone.
机译：摘要：通过实验模拟河口和海水在河口（南卡罗来纳州圣赫勒拿海峡）混合过程中陆源性溶解有机物（DOM）在阳光下的暴露，该研究研究了光化学变化如何影响其幅度和强度。河口细菌利用DOM的命运。在一系列的实验中，对从3条流入南大西洋海岸线（美国）河口的黑水河中收集的水样进行了测试，暴露于光下导致相对于350 nm的溶解有机碳（DOC）浓度和DOM吸收显着降低。黑暗的控制。当这些水样品随后用河口细菌群落接种时，相对于对照处理中观察到的情况，事先暴露在光下会显着增加细菌的生长，呼吸和总DOC消耗。但是，呼吸的增加（46％至78％）始终大于增长的增加（19％至35％）。这导致细菌生长效率降低，范围从16％到33％，并且可以通过DOM光学特性的初始差异来预测。此外，尽管光照持续导致大量的NH 4 产生，但光照条件下的细菌代谢会伴随细菌对无机营养的需求显着增加（比黑暗对照组高117至243％）。这些结果表明，陆源DOM的辐射显着改变了其最终命运（CO 2 与细菌生物量的关系），并且光改变的DOM的细菌碳代谢与对无机养分的需求增加有关，这可能会大大影响沿海地区生态系统规模的碳和养分相互作用。

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