湖泊水-沉积物界面DIC和DOC交换通量及耦合关系

Exchange Fluxes and Coupling Relationship of Dissolved Inorganic Carbon and Dissolved Organic Carbon Across the Water-Sediment Interface in Lakes

以乌梁素海和岱海为研究对象,采用柱状芯样模拟法,开展了2个湖泊水-沉积物界DIC和DOC交换通量及耦合关系研究.结果表明,在夏季90 d的时间内,乌梁素海明水区沉积物表现为上覆水中DIC和DOC的碳源,DIC和DOC的平均释放速率分别为71.07 mmol·(m2·d)-1和185.09 mmol·(m2·d)-1;岱海浅、深水区沉积物整体上表现为上覆水中DIC和DOC的碳汇,浅水区DIC和DOC的平均释放速率分别为155.75 mmol·(m2·d)-1和-1 478.08 mmol·(m2·d)-1,深水区DIC和DOC的平均释放速率分别为-486.53 mmol·(m2·d)-1和-1 274.02 mmol·(m2·d)-1;岱海浅水区和乌梁素海水-沉积物界面DIC与DOC耦合作用(含量、释放速率、总量变化量的同步变化)主要受微生物摄取、微生物或非生物降解及水生植物的影响;岱海深水区水-沉积物界面DIC与DOC耦合作用则主要与Ca CO3共沉淀作用及沉积物中无机碳形态分布特征等有关.总体上,不同类型湖泊或同一湖泊不同湖区的DIC或DOC源/汇功能差异是湖泊类型、离岸距离、湖泊水文地球化学及无机碳形态分布等多种因素综合作用的结果.

In this work,the exchange fluxes and coupling relationship of dissolved inorganic carbon( DIC) and dissolved organic carbon( DOC) were investigated across the water-sediment interface in Lake Wuliangsuhai and Daihai by employing columnar simulation method. The results showed that the sediments in non-Phragmitescommunis area from Lake Wuliangsuhai functioned as the sources of DIC and DOC for overlying water,whereas the sediments from Lake Daihai as the sinks during the period of summer( 90days). In the experimental period, the average exchange rates of DIC and DOC were 71. 07 mmol·( m2·d)- 1and 185. 09mmol·( m2·d)- 1in non-Phragmitescommunis area from Lake Wuliangsuhai,respectively; while in Lake Daihai,they were 155. 75mmol·( m2·d)- 1and- 1 478. 08 mmol·( m2·d)- 1in shoal water zone, and- 486. 53 mmol·( m2·d)- 1and- 1 274. 02mmol·( m2·d)- 1in deep water zone,respectively. The coupling effects between DIC and DOC were governed by hydrobios,microbial uptake,abiotic and microbiological degradation in Lake Wuliangsuhai and in shoal water zone of Lake Daihai; while they were closely related to the coprecipitation process of Ca CO3 and the fraction distribution of inorganic carbon in sediments in deep water zone of Lake Daihai. In summary,the sink or source functions of sediments could be considered as the results of synthetic action of lake types,offshore distance,geohydrochemistry and the fraction distribution of inorganic carbon.