Simulation study of CO2 sequestration potential of the Mary Lee coal zone, Black Warrior basin

Significant potential exists for CO₂ sequestration in coalbed methane reservoirs of the Black Warrior basin. Reservoir simulation is an appropriate approach to estimate both the storage capacity and methane recovery enhancement. However, prior to a reliable reservoir modeling and simulation, conducting an accurate and comprehensive reservoir characterization study is necessary. The purpose of the present study is twofold: (a) to provide a rigorous reservoir characterization study required for modeling Mary Lee coal group in the Blue Creek field of the Black Warrior basin; (b) to run fluid flow simulations to predict the performance of ECBM process applied to an under pressured zone of the Mary Lee coal group. According to the current well configuration of Blue Creek field, three applicable well patterns, namely a direct line drive, an inverted 5-spot and a normal 5-spot were separately (i.e., in three distinct cases) used for simulating ECBM. Simulations were run on an approximately 32 ha (80-acre) drainage area, and included coal matrix shrinkage/swelling effects. The injected gas was assumed to be pure CO₂. Using an inverted 5-spot pattern, simulations predicted that after 7.5 years of CO₂ injection, approximately 32,000 tonnes of CO₂ would be sequestered per 32 ha of this zone and that methane recovery would be enhanced by 36 %. Using a normal 5-spot pattern, CO₂ breakthrough would occur 2.4 years earlier, and about 40,000 tonnes CO₂ would be sequestered. However, methane production would be enhanced by 33 %. Considering methane recovery enhancement, direct line drive pattern delivered poor results in comparison with two other patterns. As expected, the results also showed that CO₂ injection would increase water production.     

Effects of Compost Addition on Pyrene Removal from Soil Cultivated with Three Selected Plant Species

A greenhouse pot experiment was conducted to investigate the effect of compost addition on the phytoremediation ability of Medicago sativa, Brassica napus, and Lolium perenne in soils contaminated with pyrene. Pyrene concentrations were evaluated after 90 days in contaminated uncultivated amended‐soil, cultivated amended‐soils, and shoots and roots of the three plant species. The addition of compost enhances significantly pyrene dissipation from 16 to 26% in uncultivated soil, whereas in cultivated soils it appears not to have any significant effect on pyrene dissipation, neither pyrene was detectable in shoots and roots of the three species examined. The high partition coefficient of pyrene to compost dissolved organic matter (DOM) and the molar absorptivity values at 280 nm (ε₂₈₀) indicate a high affinity of pyrene to compost DOM molecules, likely due to their aromatic character. These results suggest that compost improves pyrene removal from soil, possibly by promoting its adsorption onto compost DOM. This property is very important in indicating that compost can be used, besides for its amendment capacity, also as a potential tool for remediation of contaminated soils.     

Development of a thermal desorption method for the analysis of particle associated polycyclic aromatic hydrocarbons in ambient air

An investigation for the analysis of polycyclic aromatic hydrocarbons in airborne particulates using thermal desorption and gas chromatography-mass spectrometry is described. Samples are obtained from ambient air using fibreglass filters and the volatile material from the filter is thermally desorbed to gas chromatograph. A 30 meter capillary column is used to separate the hydrocarbons and eight polyaromatic hydrocarbons are used to test the method and recovery is >95%. The eight polycyclic aromatic hydrocarbons anthracene, phenanthrene, fluoranthrene, pyrene, benzo (a) anthracene, chrysene, benzo (a) pyrene and benzo (e) pyrene were the most abundant PAHs found in the samples of ambient air with current method at Uxbridge-London. Application of the measurement of polycyclic aromatic hydrocarbons in ambient air samples shows that the hydrocarbons trapped in the particle phase to a lesser degree at higher ambient temperature. In conclusion a method has been developed to transfer the PAHs in particle phase from a filter to GC-MS by thermal desorption. A standard mixture of PAHs, when absorbed onto the filter, did lead to strong analyte absorbent interactions by the high percent recovery of the sample.     

Inelastic seismic response of stiffening systems and development of demand spectrum: Application to MSSS bridges

A stiffening system is a system that increases its stiffness as it goes under large displacements. Such behavioural characteristic can result from constitutive behaviour or at the structural level often from closure of gaps between various components (sub‐systems) of the structure. An example of the latter situation is multi‐span simply supported (MSSS) bridges under horizontal earthquake ground motion. Unlike softening systems, stiffening systems have not been studied. In addition to the need for more understanding of the seismic response of stiffening systems, there is a need to develop response spectrum that can be used in design. Several parameters including gap size and ratios of sub‐systems stiffness, strength, and mass control the behaviour of a stiffening system. In this study, a simplified stiffening model is developed and over 367 000 cases are analysed to investigate the nonlinear stiffening behaviour and pounding. Parameters considered also include ground motion characteristic. Results are evaluated and compared in terms of displacement and dissipated hysteretic energy. Parameter study results show that, on average, the displacement response is lower for stiffening systems, however, they dissipates higher hysteretic energy, due to higher yield cycles and yield excursions, and can possibly sustain more damage than a bilinear, elastic–plastic system. Using parameter study database, design response spectrum for stiffening systems is also proposed and its practical application is demonstrated through its application to an MSSS bridge. Results of this study goes beyond MSSS bridges and will have application for many structural systems where response is characterized by a stiffening behaviour. Copyright © 2007 John Wiley & Sons, Ltd.     

Using stable isotopes to estimate travel times in a data‐sparse Arctic catchment: Challenges and possible solutions

Use of isotopes to quantify the temporal dynamics of the transformation of precipitation into run‐off has revealed fundamental new insights into catchment flow paths and mixing processes that influence biogeochemical transport. However, catchments underlain by permafrost have received little attention in isotope‐based studies, despite their global importance in terms of rapid environmental change. These high‐latitude regions offer limited access for data collection during critical periods (e.g., early phases of snowmelt). Additionally, spatio‐temporal variable freeze–thaw cycles, together with the development of an active layer, have a time variant influence on catchment hydrology. All of these characteristics make the application of traditional transit time estimation approaches challenging. We describe an isotope‐based study undertaken to provide a preliminary assessment of travel times at Siksik Creek in the western Canadian Arctic. We adopted a model–data fusion approach to estimate the volumes and isotopic characteristics of snowpack and meltwater. Using samples collected in the spring/summer, we characterize the isotopic composition of summer rainfall, melt from snow, soil water, and stream water. In addition, soil moisture dynamics and the temporal evolution of the active layer profile were monitored. First approximations of transit times were estimated for soil and streamwater compositions using lumped convolution integral models and temporally variable inputs including snowmelt, ice thaw, and summer rainfall. Comparing transit time estimates using a variety of inputs revealed that transit time was best estimated using all available inflows (i.e., snowmelt, soil ice thaw, and rainfall). Early spring transit times were short, dominated by snowmelt and soil ice thaw and limited catchment storage when soils are predominantly frozen. However, significant and increasing mixing with water in the active layer during the summer resulted in more damped steam water variation and longer mean travel times (~1.5 years). The study has also highlighted key data needs to better constrain travel time estimates in permafrost catchments.     

Origin and Formation of Sulfate in Soils from Three Ohio Counties

Sulfate induced heave has been attributed to ettringite, which can form when there is an elevated pH as well as sufficient amounts of aluminum, sulfate, calcium and water present. The primary objective of this project was to study the origin and formation of sulfate in Ohio soils in order to assist with selecting appropriate soil stabilization strategies for future roadway construction. Three roadway construction project areas were evaluated: State Route 2 in Lake (LAK) County, US Highway 24 in Paulding and Defiance Counties and Interstate-71 in Morrow (MRW) County. Defiance County had the most soil samples with sulfate concentrations above acceptable risk level (3000 mg/kg SO₄). Morrow County had the next highest number of unacceptable sulfate levels. Of the 42 Lake County soils analyzed, 11 contained sulfate above acceptable risk level. The soils surrounding the road construction activities along State Route 2 and US-24 had similar geological characteristics. A potential source of sulfate in Paulding and Defiance Counties was attributed to the direct deposition of gypsum as a soil amendment for farmlands. The most likely sources of soil sulfate in Morrow County were deposition of gypsum for farmland activities and the oxidative weathering of pyrite.     

科尔沁沙地沙丘植被对丘间低地水体的影响北大核心CSCD

在流动沙丘以建立固沙植被的方式向固定沙丘转化的过程中,植被将改变沙丘水分再分配过程,影响沙丘的水文调节功能,甚至可能引起沙丘生态系统水资源失衡。为探明植被对沙丘水文调解功能的影响,以科尔沁沙地不同植被盖度的沙丘-丘间地水体组合体为研究对象,于2021年生长季开展了沙丘植被盖度、丘间低地水体变化特征、气象因素的动态观测,以期明确沙丘植被变化对丘间低地水体的影响。结果表明:(1)沙丘植被盖度影响沙丘水分对外补给能力,随着沙丘表面固沙植被盖度增加,单位面积沙丘对外水分补给能力降低,表现为流动沙丘(58.25 mm)>半固定沙丘(24.75 mm)>固定沙丘(14.87 mm),占同期降水量的比例分别为21.39%、9.09%、5.46%。(2)生长季流域降水补给量、植被盖度、气温显著影响沙丘对丘间低地水体的水分补给量,丘间低地水体获补量与流域降水补给量显著正相关,与植被盖度、气温极显著负相关。(3)依据水量平衡原理推导出沙丘水分对外补给量(Y)与影响因素(降水补给量X_(1),植被盖度X_(2),平均气温X_(3))的关系模型,Y=1052.737+0.1X_(1)-11.459X_(2)-37.585X_(3),R2=0.641。可根据模型预测沙丘水分对外补给量,为流动沙丘生物治理模式的合理选择提供支持。     

Evaluation of oxidative enzymes for efficient oxidation of aniline and phenolic pollutants

Tyrosinases, laccases, and peroxidases are three important groups of oxidative enzymes. A characteristic feature of these enzymes is their ability for the oxidation of aniline and phenolic compounds. Literature review reveals some overlap between the organic substrates of these enzymes, but how exactly they are different and how much they have in common from both substrate structure and rate of oxidation points of views. Can they complete functional efficiency of each other when co-immobilized in a multi-enzymes system? To address these questions, edible mushroom (Agaricus bisporus) tyrosinase, Neurospora crassa laccase, and horseradish peroxidase were examined for the oxidation of azo derivatives of anilines and phenols. These substances were selected because their enzymatic degradation is of interest to environmentalists and can be followed spectrophotometrically. Experiments showed that tyrosinase and laccase had limitations in oxidizing these substances, especially anilines, while peroxidase oxidized all the selected compounds. However, substrates carrying electron-withdrawing substituents had slower oxidation. Co-immobilization of tyrosinase and laccase would be effective against phenolic compounds, but phenols oxidation proceeds faster (between 100 and 500 times) if peroxidase and H₂O₂ are used. Combination of peroxidase and H₂O₂, instead of co-immobilization of tyrosinase, laccase, and peroxidase, seems to be more promising for the removal of organic pollutants from contaminated water resources.     

Failure Behavior of Room and Pillar with Different Room Configuration Under Uniaxial Loading Using Experimental Test and Numerical Simulation

Geotechnical and Geological Engineering - This paper investigates different configuration of the room and pillar under uniaxial loading using experimental and particle flow code in two dimension...