Kinetics and mechanisms of dissolved organic carbon retention in a headwater stream
Kinetics and mechanisms of dissolved organic carbon retention in a headwater stream
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源头水流中溶解有机碳滞留的动力学和机制
DOI：
10.1007/bf02187376
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发表时间：
1985
期刊：
影响因子：
4
通讯作者：
W. H. Dowell
中科院分区：
文献类型：
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作者：
W. H. Dowell
将秋季脱落的枫叶、桦叶和云杉针叶的冻干水提取物添加到新罕布什尔州贝尔布鲁克的三级河段中，其浓度与预测的落叶高峰期间的浓度相似。每个物种的渗滤液都被迅速从溶液中去除。添加的渗滤液初始浓度约为 5 mgl−1，从添加点向下游移动的前 5 小时内，溶解有机物 (DOC) 的吸收范围为 73 至 130 mg m−2 h−1。相对于酚类或未鉴定的 DOC，低分子量的 DOC 或单体碳水化合物没有被优先去除。在实验室实验中，流沉积物和有机碎片迅速从溶液中去除了 DOC。糖枫渗滤液单独在溪水中没有发生明显的絮凝或微生物同化。溪流沉积物显示，随着叶渗滤液的添加，呼吸作用略有增加，但向有机碎片中添加渗滤液后，呼吸作用没有增加。由于河流沉积物中高浓度的可交换铁和铝而产生的非生物吸附可能是现场实验中观察到的叶子渗滤液快速去除的原因。非生物过程似乎将 DOC 保留在溪流中，从而允许溪流微生物群对溶解的有机碳进行后续代谢。
Freeze-dried aqueous extracts of autumn-shed maple leaves, birch leaves, and spruce needles were added to a third-order reach of Bear Brook, New Hampshire at concentrations similar to those predicted to occur during peak leaf fall. Leachate from each species was rapidly removed from solution. With initial concentrations of added leachate of approximately 5 mgl−1, dissolved organics (DOC) uptake ranged from 73 to 130 mg m−2 h−1 for the first five hours of travel downstream from the point of addition. There was no preferential removal of DOC of low molecular weight, or of monomeric carbohydrates relative to phenolics or unidentified DOC.Stream sediments and organic debris rapidly removed DOC from solution in laboratory experiments. No significant flocculation or microbial assimilation of sugar maple leachate occurred in stream water alone. Stream sediments showed small increases in respiration with addition of leaf leachate, but no increase in respiration occurred upon addition of leachate to organic debris. Abiotic adsorption due to the high concentrations of exchangeable iron and aluminium in stream sediments may be responsible for much of the rapid removal of leaf leachate observed in field experiments. Abiotic processes appear to retain DOC within the stream, thereby allowing subsequent metabolism of dissolved organic carbon by stream microflora.