Dissolved Organic Matter Quality and Bioavailability Changes Across an Urbanization Gradient in Headwater Streams
Dissolved Organic Matter Quality and Bioavailability Changes Across an Urbanization Gradient in Headwater Streams
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DOI：
10.1021/es501422z
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发表时间：
2014-07-15
影响因子：
11.4
通讯作者：
Palmer, Margaret A.
中科院分区：
文献类型：
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作者：
Hosen, Jacob D.;McDonough, Owen T.;Palmer, Margaret A.
景观城市化广泛地改变流域和河流生态系统，但非点源城市投入的数量，质量和溶解有机物（DOM）的最终命运的影响知之甚少。我们评估了沿着城市化梯度（即，百分比流域不透水覆盖）;没有一条溪流有点源排放。DOM的质量进行了测量，使用荧光激发-发射矩阵（EEMs）与并行因子分析（PARAFAC）。使用可生物降解的溶解有机碳（BDOC）孵育评估生物利用度。结果表明，流域不透水覆盖显着相关流DOM组成：增加不透水覆盖与天然腐殖酸样DOM和人为富里酸样和蛋白质样DOM的量减少。DOM的微生物生物有效性在春季和夏季的城市化流更大，并与减少比例的腐殖类DOM和增加比例的蛋白质类DOM。增加的生物利用度与BDOC孵育过程中提供给样品的初始微生物群落的胞外酶活性升高有关。这些研究结果表明，流DOM质量的变化，由于流域城市化可能会影响流生态系统的新陈代谢，并最终通过河流系统输送的有机碳的命运。
Landscape urbanization broadly alters watersheds and stream ecosystems, yet the impact of nonpoint source urban inputs on the quantity, quality, and ultimate fate of dissolved organic matter (DOM) is poorly understood. We assessed DOM quality and microbial bioavailability in eight first-order Coastal Plain headwater streams along a gradient of urbanization (i.e., percent watershed impervious cover); none of the streams had point source discharges. DOM quality was measured using fluorescence excitation-emission matrices (EEMs) coupled with parallel factor analysis (PARAFAC). Bioavallability was assessed using biodegradable dissolved organic carbon (BDOC) incubations. Results showed that watershed impervious cover was significantly related to stream DOM composition: increasing impervious cover was associated with decreased amounts of natural humic-like DOM and enriched amounts of anthropogenic fulvic acid-like and protein-like DOM. Microbial bioavailability of DOM was greater in urbanized streams during spring and summer, and was related to decreasing proportions of humic-like DOM and increasing proportions of protein-like DOM. Increased bioavallability was associated with elevated extracellular enzyme activity of the initial microbial community supplied to samples during BDOC incubations. These findings indicate that changes in stream DOM quality due to watershed urbanization may impact stream ecosystem metabolism and ultimately the fate of organic carbon transported through fluvial systems.