Western China has experienced rapid industrialization and urbanization since the implementation of the National Western Development Strategies (the "Go West" movement) in 1999. This transition has affected the spatial and temporal characteristics of nitrogen dioxide (NO₂) pollution. In this study, we analyze the trends and variability of tropospheric NO₂ vertical column densities (VCDs) from 2005 to 2013 over Western China, based on a wavelet analysis on monthly mean NO₂ data derived from the Ozone Monitoring Instrument (OMI) measurements. We focus on the anthropogenic NO₂ by subtracting region-specific "background" values dominated by natural sources. After removing the background influences, we find significant anthropogenic NO₂ growth over Western China between 2005 and 2013 (8.6 ± 0.9 % yr⁻¹ on average, relative to 2005), with the largest increments (15 % yr⁻¹ or more) over parts of several city clusters. The NO₂ pollution in most provincial-level regions rose rapidly from 2005 to 2011 but stabilized or declined afterwards. The NO₂ trends were driven mainly by changes in anthropogenic emissions, as confirmed by a nested GEOS-Chem model simulation and a comparison with Chinese official emission statistics. The rate of NO₂ growth during 2005–2013 reaches 11.3 ± 1.0 % yr⁻¹ over Northwestern China, exceeding the rates over Southwestern China (5.9 ± 0.6 % yr⁻¹) and the three well-known polluted regions in the east (5.3 ± 0.8 % yr⁻¹ over Beijing-Tianjin-Hebei, 4.0 ± 0.6 % yr⁻¹ over the Yangtze River Delta, and −3.3 ± 0.3 % yr⁻¹ over the Pearl River Delta). Subsequent socioeconomic analyses suggest that the rapid NO₂ growth over Northwestern China is likely related to the fast developing resource- and pollution-intensive industries along with the "Go West" movement as well as relatively weak emission controls. Further efforts should be made to alleviate NO_x pollution to achieve sustainable development in Western China.

By following an empirical approach, this study proves that joint regional air pollution control (JRAPC) in the Beijing-Tianjin-Hebei region will save the expense on air pollution control compared with a locally-based pollution control strategy. The evidences below were found. (A) Local pollutant concentration in some of the cities is significantly affected by emissions from their surrounding areas. (B) There is heterogeneity in the marginal pollutant concentration reduction cost among various districts as a result of the cities' varying contribution of unit emission reduction to the pollutant concentration reduction, and their diverse unit cost of emission reduction brought about by their different industry composition. The results imply that the cost-efficiency of air pollution control will be improved in China if the conventional locally based regime of air pollution control can shift to a regionally based one.

Development of shale gas resources is expected to play an important role in China's projected transition to a low-carbon energy future. The question arises whether the availability of water could limit this development. The paper considers a range of scenarios to define the demand for water needed to accommodate China's projected shale gas production through 2020. Based on data from the gas field at Fuling, the first large-scale shale gas field in China, it is concluded that the water intensity for shale gas development in China (water demand per unit lateral length) is likely to exceed that in the US by about 50%. Fuling field would require a total of 39.9–132.9Mm3 of water to achieve full development of its shale gas, with well spacing assumed to vary between 300 and 1000m. To achieve the 2020 production goal set by Sinopec, the key Chinese developer, water consumption is projected to peak at 7.22Mm3 in 2018. Maximum water consumption would account for 1% and 3%, respectively, of the available water resource and annual water use in the Fuling district. To achieve China's nationwide shale gas production goal set for 2020, water consumption is projected to peak at 15.03Mm3 in 2019 in a high-use scenario. It is concluded that supplies of water are adequate to meet demand in Fuling and most projected shale plays in China, with the exception of localized regions in the Tarim and Jungger Basins