School of Environmental Science and Spatial Informatics, China University of Mining and Technology
School of Architectural Decoration, Jiangsu Vocational Institute of Architectural Technology

湿地作为陆地生态系统最重要的碳汇，是减缓全球大气中二氧化碳含量上升和全球气候变暖的重要途径。目前研究多针对于自然湿地中储碳量和碳密度的研究，对于因煤炭开采形成的采煤塌陷湿地碳密度及其变化研究则相对较少。基于对采煤塌陷湿地水体和沉积物中碳含量和影响因子的调查，研究采煤沉陷湿地沉积物−水界面不同形态碳交换通量规律，评估沉积物对于上覆水中碳素的源/汇特征，探讨不同环境因子单一及交互作用下沉积物−水界面各形态碳的交换通量的变化规律。针对徐州九里湖采煤塌陷湿地沉积物和水体进行研究，分别于 2020年12月、2021年4月和2021年8月采集沉积物和上覆水，分析沉积物和水体中碳素的赋存特征以及影响碳素含量的关键因子。通过室内模拟试验，进行沉积物−水界面溶解性碳交换通量研究，并探讨主要环境因子对溶解性碳交换通量的影响。最后基于响应面法构建沉积物−水界面溶解性碳交换通量回归模型，预测采煤沉陷湿地溶解性碳最小释放条件，估算采煤塌陷湿地溶解性碳释放总量。结果如下：温度升高会导致溶解性碳交换通量增大，而pH对其影响较小；在高氧(9.0 mg/L)和低氧(3.0 mg/L)条件下，溶解性有机碳(DOC)和溶解性无机碳(DIC)交换通量相对较高，在中氧(6.0 mg/L)条件下，相对较小。得出在环境因子交互作用下的最优化条件，当温度为 5.69 ℃、pH为7.18、溶解氧DO为6.38 mg/L时，DOC和DIC交换通量区的最小值分别为2.32、3.54 mg/(m2·h)。估算出湿地8月沉积物DOC和DIC释放总量最高，分别为1.75、5.76 t；12月沉积物DOC和DIC释放总量最低，分别为0.98、2.01 t。结果表明，环境因子对 DOC 和 DIC 交换通量均有不同程度影响，温度通过改变吸附能力和生物活性的方式使 DOC 和DIC 交换通量随温度增加而增大；pH 影响着沉积物中碳酸盐的溶解度使得 DIC在碱性环境中增加不明显，但对 DOC 交换通量影响较小。DOC和DIC释放总量变化规律一致，夏季温度较高，沉积物微生物活性强，促进DOC和DIC向上覆水中大量释放，冬季温度低，释放作用显著下降。沉积物−水界面溶解性碳交换通量只考虑了温度、pH 和 DO三个条件，然而影响物质在沉积物−水界面的迁移转化还包括沉积物自身特性、生物扰动以及重金属等因素，对于因采煤形成的湿地，沉积物中金属离子对溶解性碳的释放更应引起注意，在后面的研究中可以微生物为切入点，探究沉积物碳“源”与“汇”转换的临界条件。

The most important thing for wetlands as terrestrial ecosystems is carbon, which is an important way to slow down the rise of dihydride carbon content in the global atmosphere and global warming. At present, most studies focus on carbon storage and carbon density in natural wetlands. However, there are relatively few studies on carbon density and its changes in coal mining collapse wetlands. Based on the investigation of carbon content and influencing factors in water bodies and sediments of coal mining subsidence wetlands, this paper studies the carbon exchange fluxes of different forms at the sediment-water interface of coal mining subsidence wetlands, evaluates the source/sink characteristics of sediments for carbon in overlying water, and discusses the changes of the exchange fluxes of various forms of carbon at the sediment-water interface under the single and interactive interaction of different environmental factors. The sediment and overlying water were collected in December 2020, April 2021 and August 2021, respectively, to analyze the occurrence characteristics of carbon in the sediment and water and the key factors affecting carbon content in the coal mining collapse wetland of Jiuli Lake. The dissolved carbon exchange fluxes at the sediment-water interface were studied through laboratory simulation experiments, and the effects of major environmental factors on dissolved carbon exchange fluxes were discussed. Finally, a regression model of dissolved carbon exchange flux at the sediment-water interface was constructed based on the response surface method to predict the minimum release conditions of dissolved carbon in coal mining subsidence wetlands and estimate the total amount of dissolved carbon release in coal mining subsidence wetlands. The results are as follows: temperature increase leads to the increase of dissolved carbon exchange flux, while pH has little effect on it; The exchange fluxes of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) were relatively high under high oxygen (9.0 mg/L) and low oxygen (3.0 mg/L) conditions, and relatively small under medium oxygen (6.0 mg/L) conditions. The optimal conditions under the interaction of environmental factors are obtained. When the temperature is 5.69 ℃, the pH is 7.18, and the DO is 6.38 mg/L the minimum exchange flux region of DOC and DIC is 2.32 and 3.54 mg/(m2·h), respectively. It was estimated that the total amount of DOC and DIC released in wetland sediments in August was the highest, which was 1.75 t and 5.76 t respectively. The total release of DOC and DIC was the lowest in December, which were 0.98 t and 2.01 t, respectively. The results showed that the environmental factors had different degrees of influence on the exchange fluxes of DOC and DIC, and the exchange fluxes of DOC and DIC increased with the increase of temperature by changing the adsorption capacity and biological activity. pH affects the solubility of carbonate in the sediment, so DIC does not increase significantly in alkaline environment, but has little effect on DOC exchange flux. The variation law of total release of DOC and DIC is consistent. The high temperature in summer and strong microbial activity in sediments promote the release of DOC and DIC in the upward overlying water, while the low temperature in winter significantly reduces the release effect. Only temperature, pH and DO are considered for dissolved carbon exchange fluxes at the sediment-water interface. However, factors affecting the migration and transformation of substances at the sediment-water interface include the characteristics of sediments themselves, bioturbation and heavy metals, etc. For wetlands formed by coal mining, the release of dissolved carbon by metal ions in sediments should be paid more attention. In the following research, microorganisms can be used as the starting point to explore the critical conditions for the conversion of sediment carbon “source” and “sink”.

路平，张浩然，任峰，等. 基于响应面法游湖沉积物−水界面溶解性碳交换通量[J]. 煤炭学报，2023，48(7)：2906−2915.

LU Ping，ZHANG Haoran，REN Feng，et al. Dissolved carbon exchange flux at sediment-water interface in coal mine subsidence wetland based on response surface method[J]. Journal of China Coal Society，2023，48(7)：2906−2915.