Abstract Miyun County, located in the northeast of Chinese capital Beijing, was underwent remarkable variations in land use in recent years. This paper aimed to detect changes in land use of Miyun from 1997 to 2005, and to qualify the response of ecosystem to LUCC based on ecosystem services valuation. With two-periods TM images, we got land use change data, and then ecosystem services values were calculated using ecosystem services valuation coefficients proposed by Chinese scholar Xie Gaodi. Results showed that water area, farm land and unused land decreased while residential land, forest land, grassland and orchard land increased during the study period. The loss of ESV was RMB 206 million and the main reason was the decrease of water area and farm land area. As for spatial variation, there were most dramatically land use change and ESV decline in reservoir ecological protection region. The coefficient sensitivity analysis indicates that valuation coefficients used in the study are suitable and results are reasonable. The driving forces of ESV loss were rapid population growth and economic development. More work should be done to make eco-environment stay healthy. 相似文献
The wide use of polyacrylamide (PAM) in enhanced oil recovery generates a large amount of polymer-bearing wastewater featuring high viscosity and difficult viscosity reduction, making the treatment of wastewater increasingly difficult. In this paper, the experimental study on reducing the viscosity of wastewater containing polyacrylamide by using the plasma generated by dielectric barrier discharge (DBD) and the synergistic effect of catalyst γ-Al2O3 is carried out. The law of plasma reducing the viscosity of wastewater containing polyacrylamide is studied under the different conditions of amounts of γ-Al2O3 catalyst, discharge voltages, and initial concentrations of polyacrylamide-containing wastewater. The mechanism of viscosity reduction of polyacrylamide is studied through environmental scanning electron microscope (ESEM), Fourier transform infrared (FTIR) spectrometer, and X-ray photoelectron spectroscopy (XPS). The results show that the catalytic viscosity reduction is the best when the discharge voltage is 18 kV and the discharge time is 15 min. With the increase in the input of the γ-Al2O3 catalyst, the viscosity of the PAM solution decreases gradually. When the amount of γ-Al2O3 is 375 mg, the shear rate changes from 0.5 1/sec to 28 1/sec, and the viscosity of the solution containing polyacrylamide changes from 434.5 mPa·s to 40.2 mPa·s. The viscosity reduction rate of the PAM solution is 90.7%. After the catalytic viscosity reduction, the functional groups of polyacrylamide do not change much. The elemental composition of the catalyst has not changed, which is still Al, C, and O.
The atmospheric mixing ratios of methacrolein (MACR) and methyl vinyl ketone (MVK), the two specific products from isoprene oxidation in the atmosphere, were measured in Beijing from March to November, 2006. Distinct amounts of MACR and MVK were detected during vegetable growing seasons from April to October with ambient levels of 0.11–0.67 ppbv and 0.19–1.36 ppbv, respectively. The reacted isoprene and its ozone formation potentials (OFPs) in Beijing were evaluated in the range of 0.49–3.46 ppbv and 6.4–44.7 ppbv, respectively, from April to October. OFP of the reacted isoprene accounted for 10.6–23.6% of the total OFPs of VOCs (including carbonyls and isoprene) and 6.38–29.9% of the photo-chemically produced ozone. The maximum OFP of the original emitted isoprene prior to its photo-oxidation was calculated as 56.0 ppbv in August. The contribution from the reacted isoprene in Beijing to HCHO formation was also estimated to be in the range of 0.35–2.45 ppbv from April to October, which accounted for 4.6–11.5% of ambient HCHO. 相似文献