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The composite fuel of coal gangue and biomass is expected to increase the utilization rate of solid waste and compensate for the disadvantages of separate fuels. However, the NO and SO2 emissions from this composite fuel during the combustion process are a concern, but there are few studies on it. In this paper, corn cobs and wheat straws, typical agricultural biomass discarded in North China, and coal gangue from the mine in Xilingol, China, were selected for co-combustion in a fluidized bed. The emission characteristics of NO and SO2 were studied by changing the ratio of biomass to coal gangue and the combustion temperature. Studies had shown that: to a certain extent, mixing biomass, and coal gangue can reduce the NO and SO2 emissions, and mixing 20% of biomasses had the best effect on NO and SO2 emissions reduction. The SO2 emission reduction effect of wheat straws was better than that of corn cobs, and the NO emission reduction effect of corn cobs was better than that of wheat straws. The NO emissions of wheat straws and corn cobs added to the coal gangue were 6.45% and 7.93% less than those of coal gangue alone. The SO2 emissions of wheat straws and corn cobs added to the coal gangue were 27.45% and 25.94% less than those of coal gangue alone. Both NO and SO2 emissions decreased with the growth of the biomass rate; NO and SO2 emissions increased with the growth of the combustion temperature. [ABSTRACT FROM AUTHOR]

Oxygen concentration and biomass content are key factors of the combustion of a mixed sample of biomass and coal gangue. Herein, we studied the effect of oxygen concentration and biomass content and their corresponding combustion and kinetic characteristics. Experiments were conducted in a thermogravimetric analyzer under an O2/CO2 atmosphere. Results showed that the fixed carbon combustion temperature, ignition temperature, and exothermic peak temperature decreased with oxygen concentration increased. By contrast, the burning rate of volatilization increased with oxygen concentration increased. The total and maximum loss rates of the sample, the burnout temperature, the exothermic peak temperature, and the comprehensive combustion index S gradually increased. As oxygen concentration increased, the activation energy at the initial stage of combustion gradually decreased, whereas the activation energy at the end of the reaction gradually increased when the oxygen concentration increased. Activation energy could be rapidly reduced after a small amount of biomass was added, whereas the biomass content had no significant influence on the activation energy of the samples at the end of combustion. [ABSTRACT FROM AUTHOR]

Vegetation is a significant factor in the energy and water cycles. Changes in vegetation are affected by the natural environment and human activities. In this study, the Dalong Reservoir on the Ningyuan River in Sanya, Hainan, China, was taken as an example to set one type of buffer zone with the reservoir dam site as the center, and two types of horizontal and vertical buffer zones outwards from both banks of the river, and Landsat 5 remote sensing image data and the vegetation data were applied. A coverage estimation model was used to study the temporal and spatial changes in surface vegetation in three types of buffer zones, and the characteristics of the surface vegetation changes in the preterm, midterm and late-term reservoir construction periods were analyzed. The results showed that, (1) During the years 2000 and 2010, the vegetation coverage first decreased and then increased with time in the scope of the research. During preterm construction (2000-2004), the vegetation coverage in the upstream region decreased while that in the downstream region increased. During midterm construction (2004-2006), the declining rate of vegetation coverage downstream was greater than that upstream, but the influence of reservoir construction on vegetation coverage decreased over time in the late-term construction period (2007-2010); (2) Along the direction of the river length, the vegetation coverage showed a downtrend along with the river flow direction during the whole period (2000-2010), and the influence of reservoir construction on vegetation coverage gradually decreased as the distance from the reservoir increased; (3) Along the direction of the river width, the vegetation coverage in the preterm and midterm construction periods (2000-2006) increased with increasing distance from the riverbanks; (4) The vegetation coverage showed a significant increasing trend with increasing distance from the reservoir. The research results can provide a theoretical reference for reducing the risk of vegetation degradation, strengthening the governance of the ecological environment, and promoting the ecological construction of "landscapes, forests, fields, lakes and grass". [ABSTRACT FROM AUTHOR]