Biodegradability of fractions of dissolved organic carbon leached from decomposing leaf litter.
Biodegradability of fractions of dissolved organic carbon leached from decomposing leaf litter.
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从分解的落叶中浸出的溶解有机碳部分的生物降解性。
DOI：
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发表时间：
2005
影响因子：
11.4
通讯作者：
R. Qualls
中科院分区：
文献类型：
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作者：
R. Qualls
有机物分解过程中浸出的溶解有机物对于生态系统根部营养物质的浸出、金属的淋溶和疏水性污染物的运输非常重要。本研究的目的是比较完整土壤核心中不同比例的水溶性溶解有机物的微生物矿化率。将经过 1 年分解的均匀 14C 标记的弗里蒙胡杨落叶在水中提取，并将该提取物分级为酚类、腐殖酸、黄腐酸、亲水酸和亲水中性级分。黄腐酸包含从垃圾中提取的溶解有机碳 (DOC) 中的 42.1% C。将这些部分添加到完整的土壤或沙子核心中，并收集呼吸的 14CO2。一年结束时土壤中矿化的标记底物 C 的百分比从最小到最大依次为：亲水酸 (30.5)、黄腐酸 (33.8)、腐殖酸 (39.0)、完整的未分级 DOC (43.5)、未分离的亲水酸和中性 (44.7)、酚类 (63.3)、葡萄糖 (66.4) 和亲水中性（70.2）。在接种土壤微生物的酸洗营养改良砂中，黄腐酸和葡萄糖的矿化率较低。分馏似乎将 DOC 分离成矿化率差异很大的组分。结果还支持这样的观点，即溶解的腐殖质和亲水酸部分本质上很难被微生物矿化，并且这种特性可能有助于难熔碳在土壤中移动并进入水生生态系统。
Dissolved organic matter leached from decomposing organic matter is important in the leaching of nutrients from the root zone of ecosystems, eluviation of metals, and transport of hydrophobic pollutants. The objective of this study was to compare microbial mineralization rates in intact soil cores of various fractions of water-soluble dissolved organic matter. Uniformly 14C-labeled Populus fremontii leaf litter that had decomposed for 1 year was extracted in water and this extract was fractionated into phenolic, humic acid, fulvic acid, hydrophilic acid, and hydrophilic neutral fractions. Fulvic acid comprised 42.1% of C in dissolved organic carbon (DOC) extracted from the litter. These fractions were added to intact cores of soil or sand, and respired 14CO2 was collected. The percentage of labeled substrate C mineralized in soil at the end of 1 year was, in order from least to greatest, hydrophilic acid (30.5), fulvic acid (33.8), humic acid (39.0), whole, unfractionated DOC (43.5), unseparated hydrophilic acid and neutral (44.7), phenolic (63.3), glucose (66.4), and hydrophilic neutral (70.2). In acid-washed nutrient-amended sand that was inoculated with soil microbes, mineralization rates of fulvic acid and glucose were lower. The fractionation appeared to separate the DOC into components with widely different rates of mineralization. Results also supported the ideas that the dissolved humic substance and hydrophilic acid fractions are inherently difficult for microbes to mineralize, and this property can contribute to movement of refractory C in soil and into aquatic ecosystems.