Managing Methane Emissions in Abandoned Coal Mines: Comparison of Different Recovery Technologies by Integrating Techno-Economic Analysis and Life-Cycle Assessment.

Methane emissions from worldwide increasing abandoned coal mines have posed multiple challenges of global warming, energy waste, and explosion risk. This study first profiles the dynamic patterns of coal mine methane emissions in different recovery technologies, methane extraction with drainage (MEWD, mine-water concurrently extracted and treated) and direct methane extraction (DME, noncontrol on mine-water), in two abandoned mines from Ningxia and Inner Mongolia as China's leading coal provinces. Then, we conducted a techno-economic analysis and life-cycle assessment to quantify their comprehensive benefits. The key findings are as follows: (1) MEWD can long recover methane, although the economic profits decrease with declining methane extraction volume. DME can only work for ∼5 years, after which the mine is flooded, where methane is sealed underground and not recoverable. (2) MEWD drains and further treats the mine-water with an additional 29.4-35.9 million CNY cost compared with DME, while MEWD can achieve greater life-cycle environmental benefits with more cumulative methane recovery, whose CO2-eq (GWP-100) and SO2 reductions are 64.4 and 53.4% higher than those of DME. (3) MEWD is more promising for large-scale implementation, where feed-in tariffs and carbon market measures can improve the economics for sustainable management of incremental abandoned mine methane.

Bacteria are better predictive biomarkers of environmental estrogen transmission than fungi.

The heavy reliance on estrogens in the food industry worldwide greatly contributes to the environmental release of these compounds, begetting serious public concern of their fate. Various microorganisms capable of estrogen degradation, and their catabolic pathways, have been isolated, suggesting that they can eliminate estrogens in both engineered and natural environments. Nonetheless, it remains little understood as to how potential estrogen-degrading microorganisms are distributed within those habitats. An estrogen transmission chain from swine manure to compost, compost-amended soil, and neighboring agricultural soil was investigated in five suburban areas of Beijing, China. The concentrations of major estrogen classes decreased by > 90% from manure to soils, which did not co-vary with environmental antibiotics and heavy metal concentrations. Many bacterial taxa, such as Lactobacillus and Bacteroides, could serve as potential biomarkers of estrogen concentrations, while fungi were only occasionally accurate. To explain this phenomenon, stochasticity was found to be dominant in shaping the fungal communities across all samples, while deterministic selection, arising from biotic interactions, was important for bacterial communities. Metabolic genes involved in oxidizing phenol and catalyzing oxidative ring cleavage of catechol were detected, co-varying with estrogen concentrations. These findings are important as identifying microbial biomarkers of estrogen dynamics, spanning the levels of both taxonomy and functional genes, provides valuable information for assessing estrogen bioavailability and biomarking of estrogen fate in the environment.

Analysis of the PM2.5 emission inventory and source apportionment in Jilin City, Northeast of China.

This study collected and compiled statistical data on atmospheric pollution in Jilin City, China during 2013-2014, using models and methods to calculate the source proportion of PM2.5 emitted by various sources. The statistical activity levels and emission factors of various pollution sources were found to be key parameters for obtaining the total amount of PM2.5 in the exhaust gas emitted from all types of pollution sources using an emissions model. In this study, relevant data were collected by the top-down method, and pollutant emission was calculated by the emission factor method to establish the PM2.5 pollution emission inventory of Jilin City. The source apportionment was calculated using the Chemical Mass Balance (CMB) model. Industrial process source and fixed combustion source are the largest sources of PM2.5 emission from all sources, respectively. Among the two calculation results, the results of pollution emission inventory are more accurate. The PM2.5 emission inventory in Jilin was established and countermeasures were proposed focused on the coordinated control of air pollution and the prevention and control of industrial dust pollution sources, as well as environmental management and impact assessment.