Abstract The objective of this paper is to determine the origin and variability of methane and carbon dioxide concentrations in the near-surface zone and of coalbed methane in the SW part of the Chwalowice Trough and adjacent areas of the Main Syncline of the Upper Silesian Coal Basin (USCB). For this purpose soil-gas samples were taken at 202 measuring points, arranged along 5 profiles located in the mining area of the abandoned 1 Maja mine and directly adjacent areas as well as in the vicinity of four abandoned and remediated mining shafts. The maximum methane and carbon dioxide concentrations in the gas samples measured exceeds 22 and 9 vol%, respectively. The carbon isotope composition of methane and carbon dioxide was determined in samples in which elevated concentrations of these gases were found. Moreover, seven coalbed gas samples and bituminous coals were collected from coal seams exclusively from virgin parts of the Anna, Marcel, Jastrzebie, and Zofiowka mines. These data were supplemented with results of archival research for genetic interpretation of coalbed gases. Research reveals that typical humic low- and medium-volatile bituminous coals occur in Mississippian and Pennsylvanian coal-bearing strata in the study area. Fluctuations in methane and carbon dioxide concentration in the near-surface zone are related to the lithostratigraphy and tectonics of the area as well as to complicated methane depth distribution. Faults may play an important role in the microseepage of gases from deep to the near-surface zone. The connection of near-surface gases with subsurface gases was confirmed by similar stable carbon isotope composition in the methane recorded in the soil-gas samples and in the gas samples from the coal seams and sandstones of the Carboniferous formations. Distribution of anomalous methane concentrations recorded in soil-gas samples taken from profiles may indicate natural gas accumulations in the top zone of the Pennsylvanian coal-bearing formations. One example of this kind of accumulation is the Marklowice natural gas field, located within the mining area of the Marcel coal mine. Relatively high methane concentrations measured in soil gas in the vicinity of shafts I and III indicate that the degassing systems of closed and remediated mining shafts are not fully effective. Increases in carbon dioxide concentrations in the surface zone and frequent associated decreases in methane concentration were most often the result of microbial methane oxidation.

中文翻译：

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波兰上西里西亚煤矿西南部分废弃和活跃煤矿近地表区甲烷和二氧化碳浓度的波动及其成因特征

摘要 本文的目的是确定近地表区甲烷和二氧化碳浓度以及 Chwalowice 海槽西南部分和上西里西亚煤盆地主要向斜附近地区煤层气的来源和变异性。 (USCB)。为此目的，在 202 个测量点采集了土壤气体样本，这些测量点沿着位于废弃 1 Maja 矿区和直接相邻区域以及四个废弃和修复的矿井附近的矿区的 5 个剖面排列。测量的气体样品中的最大甲烷和二氧化碳浓度分别超过 22 和 9 vol%。甲烷和二氧化碳的碳同位素组成是在发现这些气体浓度升高的样品中测定的。而且，七个煤层气样品和烟煤仅从 Anna、Marcel、Jastrzebie 和 Zofiowka 矿的原始部分的煤层中收集。这些数据得到了对煤层气成因解释的档案研究结果的补充。研究表明，研究区密西西比和宾夕法尼亚的含煤地层中含有典型的腐殖质中低挥发性烟煤。近地表区甲烷和二氧化碳浓度的波动与该地区的岩石地层和构造以及复杂的甲烷深度分布有关。断层可能在气体从深部到近地表带的微渗流中起重要作用。近地表气体与地下气体的联系通过土壤气体样品和石炭纪煤层和砂岩的气体样品中记录的甲烷中相似的稳定碳同位素组成得到证实。从剖面采集的土壤气体样本中记录的异常甲烷浓度分布可能表明天然气在宾夕法尼亚州含煤地层的顶部区域聚集。这种聚集的一个例子是位于 Marcel 煤矿矿区内的 Marklowice 天然气田。在矿井 I 和 III 附近的土壤气体中测得的甲烷浓度相对较高，这表明封闭和修复矿井的脱气系统并不完全有效。