A novel biocover with passive air diffusion system (PADS) was designed in this study. Its effect on landfill gas components in the macrocosms of simulated biocover systems was also investigated. The results show that O2 concentration increased in the whole profile of the macrocosms equipped with PADS. When simulated landfill gas (SLFG) flow rate was no more than 40 mL min(-1), the methane oxidation rate was 100%. The highest CH4 oxidation capacity reached to 31.34 mol m(-3) day(-1). Molecular microbiology analysis of the soil samples taken from the above macrocosm showed that the growth of type I methanotrophs was enhanced, attributable to enhanced air diffusion and distribution, whereas the microbial diversity and population density of type II methanotrophs were not so affected, as evidenced by the absence of any difference between the biocover equipped with PADS and that of the control. According to a phylogenic analysis, Methylobacter Methylosarcinafor type I, and Methylocystis, Methylosinus for type II, were the most prevalent species in the macrocosm with PADS. 相似文献
Environmental Science and Pollution Research - Top coal caving is a process for the rational extraction of large amounts of coal resources. However, this process readily causes release of excessive... 相似文献
It remains unclear why the area of a cyanobacterial bloom increases in a shallow lake after a typhoon passes. In this study, the mechanisms of cyanobacterial bloom expansion were investigated by studying meteorological factors, water quality, algal biomass, and bloom area in Lake Taihu before and after typhoons (2007–2016). Our results showed that typhoon-induced sediment resuspension caused a short-term increase in nutrients, but nutrients returned to pre-typhoon levels after the typhoon passages. The short-term nutrient release during a typhoon did not result in an obvious increase in Microcystis cell density in two bays of Lake Taihu (Gonghu and Meiliang). Under strong winds, Microcystis aggregates were uniformly distributed in the water column downwind and then dispersed into different directions by wind-driven currents. In particular, Microcystis in the surface water were transported to the center of Lake Taihu. After a typhoon, dispersed Microcystis refloated and formed blooms. Thus, the bloom area was enlarged compared with before a typhoon. Several days after a typhoon, the bloom area gradually reduced as a result of a steady breeze on the horizontal accumulation of Microcystis.
Synchrotron radiation offers important advantages with the use of tunable vacuum ultraviolet (VUV) lasers for molecular beam sampling mass spectrometry (MBMS). These advantages include superior signal-to-noise, soft ionization, and access to photon energies outside the limited tuning ranges of current VUV laser sources. Combining MBMS with tunable synchrotron radiation photoionization, two similar types of fuels, gasoline/oxygen and gasoline/MTBE/oxygen in low-pressure premixed laminar flame were investigated. Photoionization efficiency (PIE) measurements were used to identify the intermediates isomers within flame. The two combustion processes are discussed by comparing the intermediates and their spatial profiles within the two kinds of flame mentioned above. 相似文献
Converting biomass materials to humic acid is a sustainable method for humic acid production and achieve biomass valorization. A two-step hydrothermal treatment method was adopted in this study to produce humic acid from corn stalks. In the first step of the process, hydrochar was prepared at different hydrothermal temperatures and pH values. Their chemical properties were then analyzed, and the hydrochar-derived humic acids were produced under alkaline hydrothermal conditions (denoted as HHAalk). The hydrochar, prepared under high temperature (200 °C) and strong acidic (pH 0) conditions, achieved high HHAalk yields (i.e., 67.9 wt% and 68.8 wt% calculated based on weight of hydrochar). The sources of HHAalk formation were as follows: 1) production in the hydrochar preparation stage, and 2) increment under the alkaline hydrothermal treatment of hydrochar. The degree of hydrochar unsaturation was suggested as an indicator for evaluating the hydrochar humification potential under alkaline hydrothermal conditions. This study provides an important reference for the preparation of suitable hydrochar with high hydrothermal humification potential. 相似文献