芦岭矿塌陷塘温室气体溶存特征及水–气界面交换通量研究

Study on Dissolved Characteristics of Greenhouse Gases and Water-Air Interface Exchange Fluxes in the Subsidence Pond of Luling Coal Mine

摘要: 为探究采煤沉陷区水域温室气体排放的季节动态及其环境影响机制，本研究以安徽省芦岭矿塌陷塘为研究对象，基于顶空法、静态箱法分别对水体温室气体二氧化碳(CO₂)、甲烷(CH₄)溶存浓度及水–气界面交换通量进行季节监测，结合环境因子pH、氧化还原电位(ORP)、溶解有机碳(DOC)、总氮(TN)、总磷(TP)分析其时空变化特征与驱动因素。结果表明：(1) CH₄和CO₂浓度与通量呈现显著季节性差异，夏季CH₄浓度整体最高(8.38~9.41 ppm)，通量最高(远岸带(1#)达(42.53 ± 8.30) μmol•m⁻²•min⁻¹)，冬季最低(近岸带(3#)仅(0.33 ± 0.30) μmol•m⁻²•min⁻¹)；CO₂在春、夏季表现为“汇”(通量最低为(−64.51 ± 32.75) μmol•m⁻²•min⁻¹)，秋、冬季转为“源”(最高达(107.59 ± 19.10) μmol•m⁻²•min⁻¹)；(2) 区域差异显著：在远岸带(1#)，夏、冬季节的CH₄通量和秋、冬季节的CO₂通量均高于近岸带(3#)，可能与有机质沉积结构分布特征与矿化差异有关；(3) 相关性分析表明，CO₂排放影响水体酸碱环境，与TN、TP生物地球化学过程联系紧密(pH与CO₂通量显著负相关，r = −0.829，与TN显著正相关，r = 0.690)，CH₄通量主要依赖产甲烷菌活性及厌氧还原环境的形成。研究揭示了采煤沉陷区水域温室气体排放的季节动态与关键驱动因子，能够为矿区生态修复及“双碳”目标实现提供数据参考。

Abstract: To explore the seasonal dynamics of greenhouse gas emissions and their environmental impact mechanisms in the water area of coal mining subsidence zones, this study selected the water area of the Luling Mine subsidence zone in Anhui Province as the research object. Based on the headspace method and static chamber method, the concentrations and fluxes of greenhouse gases, including carbon dioxide (CO₂) and methane (CH₄), at the water-air interface were monitored in four seasons. The temporal and spatial variation characteristics and driving factors of these gases were analyzed in combination with environmental factors such as pH, oxidation-reduction potential (ORP), dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP). The results showed that: (1) The concentrations and fluxes of CH₄ and CO₂ exhibited significant seasonal differences. The CH₄ concentration was the highest in summer (8.38~9.41 ppm), and the flux was also the highest (up to (42.53 ± 8.30) μmol•m⁻²•min⁻¹ at the far shore (1#)), while it was the lowest in winter (only (0.33 ± 0.30) μmol•m⁻²•min⁻¹ at the near shore (3#)). CO₂ acted as a sink in spring and summer (with the lowest flux of (−64.51 ± 32.75) μmol•m⁻¹•min⁻¹), and turned into a source in autumn and winter (with the highest flux of (107.59 ± 19.10 μmol•m⁻²•min⁻¹). (2) There were significant regional differences: the CH₄ fluxes in summer and winter at the far shore zone (1#) and the CO₂ fluxes in autumn and winter were both higher than those at the near shore zone (3#), which might be related to the composition features and mineralization differences of organic matter in the sediment. (3) CO₂ emissions were significantly regulated by pH, TN, and TP (pH was extremely significantly negatively correlated with CO₂ flux, r = −0.829, and significantly positively correlated with TN, r = 0.690), while there was no significant linear relationship between CH₄ flux and physical and chemical indicators, suggesting that its generation mainly relied on the activity of methanogenic bacteria and generation of anaerobic reducing environments. This study revealed the seasonal dynamics and key driving factors of greenhouse gas emissions in the water area of coal mining subsidence zones, providing a scientific basis for ecological restoration in mining areas and the achievement of the “dual carbon” goals.