Re-evaluation of dissolved organic matter (DOM) in detritus food web

碎屑食物网中溶解有机物（DOM）的重新评估

• 批准号: 16510003
• 负责人: SATOH Yasuhiro
• 金额: $ 1.15万
• 依托单位: Yamagata University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16510003/
• 关键词: dissolved organic matter; Fe(III) precipitates; coprecipitation; availability of DOM; anoxic hypolimnion; aeration experiment; microbial loop; re-evaluation; 湖沼; 嫌気層; 曝気実験; 鉄の酸化還元; 溶存有機物の共沈; Dissolved organic matter; 微生物可使性; 鉄、マンガン

Dissolved organic matter (DOM) dominates over organic matter pool in lakes. Until 1980s, DOM was thought to be waste and useless substances in the energy flow in the lakes. However, the importance of DOM was re-evaluated. Azam et al. (1983) named "microbial loop" in which bacteria used DOM to build up their body, protozoa ate bacteria, and then zooplankton ate protozoa. Thus energy flow of microbial loop stems from DOM.On the other hand, hypolimnion of a productive lake becomes anoxic in summer, because of bacterial decomposition of organic matter from productive photosynthetic layer. Fe(III) and Mn(IV) in the lake sediment are reduced to Fe(II) and Mn(II), respectively and dissolved into hypolimnetic water. On the autumnal water circulation, these dissolved metals are oxidized to Fe(III) and Mn(IV) and the solubility of these compounds are small, resulting in the precipitation. Fe(III) precipitates coprecipitate many inorganic and organic compounds. Some DOM in natural lake water shou … More ld be coprecipitated by Fe(III) precipitates. However, no information is available on this phenomenon.The present study revealed that when hypolimnetic anoxic water from Lake Hibara agitated by a magnetic stirrer for 24 hr, dissolved oxygen (DO) increased from 0 to 7.6 mgl^<-1>, Fe(II) decreased from 98% of the total Fe to 5% and simultaneously massive yellow precipitate formed, and 32-48% DOC disappeared. When the water sample left unstirred for 48 hr, DO increased to 2.2 mgl-1, Fe(II) decreased to 31%, and 20% of DOC disappeared. The amount of disappeared DOC is too large to explain bacterial decomposition. The yellow precipitates should be Fe(III) precipitates and these precipitates must coprecipitated disappeared DOC.The mixing experiments of hypolimnetic anoxic water with aerobic surface water to simulate autumnal water circulation of a lake were conducted in this year. Duplicate incubations were carried out. The results likely suggested the coprecipitation. However, precision of the incubations were not enough to predict the difference between controls and treated samples. Methodological improvement is desired in the nest step. Less

溶解有机质（DOM）是湖泊有机质库的主要组成部分。直到20世纪80年代，DOM被认为是湖泊能量流中的废物和无用物质。然而，DOM的重要性被重新评估。Azam等人（1983）将细菌利用DOM构建身体，原生动物吃细菌，然后浮游动物吃原生动物的过程命名为“微生物环”。另一方面，由于细菌分解生产性光合层的有机质，生产性湖泊的低层在夏季变得缺氧。湖泊沉积物中的Fe（III）和Mn（IV）分别被还原为Fe（II）和Mn（II），并溶解于深湖水中。在秋季水循环中，这些溶解的金属被氧化成Fe（III）和Mn（IV），这些化合物的溶解度很小，导致沉淀。Fe（III）沉淀物共沉淀许多无机和有机化合物。天然湖水中的某些DOM应 ...更多信息 LD被Fe（III）沉淀物共沉淀。本研究表明，采用磁力搅拌器搅拌24小时后，溶解氧（DO）从0增加到7.6mgl/L<-1>，Fe（II）从占总Fe的98%下降到5%，同时形成大量黄色沉淀，32-48%的DOC消失。当水样不搅拌48小时，DO增加到2.2 mgl-1，Fe（II）下降到31%，和20%的DOC消失。DOC的消失量太大，无法解释细菌的分解。黄色沉淀物应是Fe（III）沉淀物，这些沉淀物应与消失的DOC共沉淀。进行一式两份孵育。结果可能表明共沉淀。然而，孵育的精密度不足以预测对照品和处理样品之间的差异。下一步需要改进方法。少

项目成果

Potential capacity of coprecipitation of dissolved organic carbon (DOC) with iron(III) precipitates

• DOI: 10.1007/s10201-006-0184-y
• 发表时间: 2006-10
• 期刊: Limnology
• 影响因子: 1.6
• 作者: Y. Satoh;Keiko Kikuchi;S. Kinoshita;H. Sasaki