Search

Changes in land-use, caused by rapid urbanization, lead to changes in the supply and demand for ecosystem services. Significant research has been conducted to investigate the impact of changes in the physical supply of ecosystem services on their value. However, quantifying the effects of simultaneous changes in supply and demand on the scarcity value of ecosystem services can provides a more reasonable assessment of ecosystem services, guiding their sustainable use. Therefore, this paper analyzed the changing trend of ecosystem services value in Chengdu in southwestern China from 1995 to 2015 by adjusting the value coefficients with relative changes in scarcity value. Naïve assessment, without considering the supply and demand effect on scarcity value, quantified a decline in the total value of the physical supply of ecosystem services from 1995 to 2015, with a reduction in the areas of cultivated land and woodland. However, the scarcity value of ecosystem services increased from US$ 6.04 billion in 1995 to US$ 12.03 billion (+99.17%) in 2015, when the effects of changes in supply and demand were considered. In addition, the demand for all the public-good ecosystem services increased during the study period, consistenting with Maslow's hierarchy of need and indicating that the demand structure of residents had changed during the process of urbanization. • The value of physical supply of ecosystem services declines along with the development of urbanization. • The scarcity value of ecosystem services has experienced a dramatically increase. • People's demand structure has changed with the increasing value of all the public-good ecosystem services. • The price elasticity of different ecosystem services is a key factor of scarcity value. [ABSTRACT FROM AUTHOR]

Coal resources play an important role in the world's energy development. China's coal consumption in 2022 was as high as 88.41 EJ. However, the process of energy extraction generates dust and gas, which is a serious threat to efficient production and workers' health. More than 7000 new cases of pneumoconiosis are diagnosed in China each year. To improve this situation, numerical simulation experiments were used to obtain the coupling diffusion law of airflow-gas-dust during tunnel excavation under long-pressure short-extraction ventilation and to determine the optimal distance of the exhaust duct from the working face (L E) for the purpose of cleaner production. Our experimental results demonstrated that the spatial and temporal evolution of gas-dust coupling largely depends on the distribution of the airflow field. By comparing the concentration distribution of gas and dust at different distances from the working face, the average gas concentration in the tunnels was found to be low (0.249 %) when L E = 4 m. Furthermore, the average dust concentration in the tunnel was the lowest (242.5 mg/m3) and therefore the least harmful to workers. The optimal exhaust duct distance was L E = 4 m , which not only reduces the environmental pollution in a tunnel but also ensures the occupational health of workers. [Display omitted] • Pollutant diffusion pattern under mixed ventilation was studied. • The concentration of the gas field in this case has a step distribution. • Variation of dust concentration in the work area was studied. • The optimal location for a tunnel's dust-gas control duct was determined. [ABSTRACT FROM AUTHOR]