A tree-ring based precipitation reconstruction for the Baluntai region on the southern slope of the central Tien Shan Mountains, China, since AD 1464

July-June precipitation has been reconstructed back to A.D. 1464 for the Baluntai region on the southern slope of the central Tien Shan Mountains, China, using the Picea schrenkiana tree-ring width. The reconstruction explains the variance of 51% in the observed precipitation from 1959 to 2005. By employing a 21-year moving average to the reconstruction, nine periods with above average reconstructed precipitation comprised similar to 1474-1503, 1550-1577, 1588-1619, 1658-1713, 1790-1812, 1833-1867, 1890-1907, 1923-1944, and 1988-1995 similar to; eight periods with below average reconstruction consisted of 1504-1549, 1578-1587, 1620-1657, 1714-1789, 1813-1832, 1868-1889, 1908-1922 and 1945-1987. The wet/dry periods of the reconstructed precipitation correspond well with other reconstructions. Some droughts in the historical documents are also precisely captured in the reconstruction. Precipitation variations for the southern slope of the central Tien Shan Mountains are roughly synchronous with that of the northern slope in the recent -300 year. Power spectral and wavelet analysis demonstrated the existence of significant similar to 100-y, similar to 60-y, similar to 50-y, similar to 16-y, similar to 10-y and similar to 2-y cycles of variability.</p

A tree-ring based temperature reconstruction for the Kaiduhe River watershed, northwestern China, since AD 1680: Linkages to the North Atlantic Oscillation

September March mean temperature has been reconstructed to A.D. 1680 for the Kaiduhe River watershed on the southern slope of the Tien Shan Mountains, China, using the Picea schrenkiana tree-ring width. The reconstruction explains the variance of 47% in the observed mean temperature from 1953 to 2011. Power spectral and wavelet analyses demonstrated the existence of significant 50-year and 2- to 7-year cycles of variability. The results of the spatial correlations suggest that our reconstruction contains climatic signals for Central Asia. Warm periods occurred during 1696-1708, 1730-1748, 1784-1804, 1832-1855, 1892-1903, 1924-1928, 1937-1943, and 1987-2006; while the periods of 1685-1695,1709-1729,1749-1783,1805-1831,1856-1891,1904-1923,1929-1936, and 1944-1986 were relatively cold. The significant correlation coefficient between the reconstruction and the temperature reconstruction for the Urumqi River source reveals that the temperature variations in the annual cold period for the southern and the northern slope of the central Tien Shan Mountains are roughly synchronous over the last nearly 300 years. A comparison between the reconstruction and three winter North Atlantic Oscillation indexes revealed similar long-term trends.</p

Systematic review of Chinese studies of short-term exposure to air pollution and daily mortality

Health effects attributable to air pollution exposure in Chinese population have been least understood. The authors conducted a meta-analysis on 33 time-series and case-crossover studies conducted in China to assess mortality effects of short-term exposure to particulate matter with aerodynamic diameters less than 10 and 2.5 mu m (PM10 and PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O-3) and carbon monoxide (CO). Significant associations between air pollution exposure and increased mortality risks were observed in the pooled estimates for all pollutants of interest. In specific, each 10 mu g/m(3) increase in PM2.5 was askwiated with a 0.38% (95% Confidence Interval, CI: 0.31, 0.45) increase in total mortality, a 0.51% (95% CI: 0.30, 0.73) in respiratory mortality, and a 0.44% (95% CI: 033, 0.54) in cardiovascular mortality. When current annual PM2.5 levels in mega-Chinese cities to be reduced to the WHO Air Quality Guideline (AQG) of 10 mu g/m(3), mortality attributable to short-term exposure to PM2.5 could be reduced by 2.7%, 1.7%, 2.3%, and 62% in Beijing, Shanghai, Guangzhou and Xi&#39;an, respectively. The authors recommend future studies on the nature of air pollution concentration and health effect relationships in Chinese population to support setting stringent air quality standards to improve public health.</p