Agriculture delivers significant amounts of dissolved organic matter (DOM) to streams, thereby changing the composition and biodegradability of the aquatic DOM. This study focuses on the interactive effects of DOM quality and biofilm composition on the degradation of DOM in a laboratory flume experiment. Half of the flumes were exposed to light to stimulate algal growth, the other half was shaded. Leachates of deciduous leaves, maize leaves, and cow dung were added to the flumes in a single pulse and changes of DOC (dissolved organic carbon) and nutrient concentrations, DOM composition (absorbance and fluorescence data), chlorophyll-a concentrations, bacterial abundances, and enzymatic activities were recorded over a week. DOM was taken up with rates of 50, 109, and 136 µg DOC L−1 h−1 for dung, leaf, and maize leachates, respectively, in the light flumes and 37, 80, and 170 µg DOC L−1 h−1 in the dark flumes. DOC uptake correlated strongly with initial SRP (soluble reactive phosphorus) and DOC concentrations, but barely with DOM components and indices. Algae mostly stimulated the microbial DOC uptake, but the effects differed among differently aged biofilms. We developed a conceptual model of intrinsic (DOM quality) and external (environmental) controlling factors on DOM degradation, with the microbial community acting as biotic filter.

中文翻译：

---

溶解的有机物质量和生物膜组成影响流槽中微生物有机物的吸收

农业向河流输送了大量溶解有机物 (DOM)，从而改变了水生 DOM 的组成和生物降解性。本研究侧重于实验室水槽实验中 DOM 质量和生物膜成分对 DOM 降解的交互影响。一半的水槽暴露在光下以刺激藻类生长，另一半则被遮蔽。落叶叶、玉米叶和牛粪的渗滤液以单脉冲方式添加到水槽中，DOC（溶解有机碳）和养分浓度、DOM 组成（吸光度和荧光数据）、叶绿素-a 浓度、细菌丰度、并记录酶活性超过一周。DOM 分别以 50、109 和 136 µg DOC L−1 h−1 的比率用于粪便、树叶和玉米渗滤液，在浅水槽中和 37、80 和 170 µg DOC L−1 h−1 在黑暗水槽中。DOC 吸收与初始 SRP（可溶性活性磷）和 DOC 浓度密切相关，但与 DOM 成分和指数几乎没有相关性。藻类主要刺激微生物 DOC 吸收，但不同老化生物膜的作用不同。我们开发了一个关于 DOM 降解的内在（DOM 质量）和外部（环境）控制因素的概念模型，其中微生物群落充当生物过滤器。