Time filter

Source Type

Mamat Z.,Xinjiang University | Yimit H.,Xinjiang Normal University | Ji R.Z.A.,Xinjiang Meteorological Observatory | Eziz M.,Xinjiang Normal University
Science of the Total Environment

A total of 469 surface soil samples were collected from the Yanqi basin in northwest China and evaluated for levels of ten heavy metals. Multivariate statistical analyses were used to study sources of and map the spatial distribution of heavy metals, as well as determine the relationship between land use types and soil source materials. It was found that: (1) the average amounts of ten heavy metals in the Yanqi basin were all below the national soil environmental quality standards of China (GB15618-1998), but the average amount of Cd, Hg, Mn, Ni, Pb, and Zn all exceeded the heavy metal background levels of soil in Xinjiang, China and exhibited accumulation. The ten heavy metals analyzed in this study can be categorized into four principal components as follows: Principal component 1 was Co, Cr, Mn, Ni, and Zn, and principal component 3 was As and Cu. Both of these originated from a natural geological background. Principal component 2 consisted of Cd and Pb and originated from industrial, agricultural and transportation influences. Principal component 4 consisted of Hg and was due to industrial influences. Our study found that Pb and Zn were a large part in the principal components 1 and 3 and were influenced by a combination of geologic background and human activity. (2) Heavy metals Cd and Hg were at high levels in construction land and farmland, while Co, Cr, Cu, Mn, and Ni were significantly higher in lacustrine deposits than in sandy shale from weathered material, coarse crystalline rock weathered material, and diluvial material. The land use types correlated significantly with the accumulation of Cd and Hg, and the soil parent material was the major factor for the accumulation of As, Co, Cr, Cu, Mn, and Ni. (3) The single element, element integration and the corresponding principal component presented similar spatial patterns of hazardous risk. Following comprehensive assessment of all elements, the high risk regions were found to be located in densely-populated urban areas and western parts of the study area. This was attributed to the higher geological background in the western part and strong human influence in the central part. Research shows that Cd, Hg, Pb, and Zn were locally enriched in the basin and this warrants increased attention. © 2014. Source

Comprehensive 25-year analysis of dense fog at Urumqi Diwopu International Airport (a major airport in western China) is performed using hourly weather data from January 1985 through December 2009 in an effort to better understand the climatological aspects of the phenomenon. The results show that dense fog is typically a cold-season phenomenon with more than 99 % of dense fog days occur from November through March. Within a day, dense fog peaks during the early morning hours and reaches a minimum in the late afternoon to early night. Most of dense fog events (68.2 %) lasted less than 3 h. Temperatures cooling to the range of −10 to −5 °C, and wind speeds of under 2 m s−1 are optimum for dense fog occurrences. Dense fog occurrences as brief as a couple of hours can disrupt air traffic locally even nationwide and affect flight on-time performance significantly, causing huge losses to both commercial airlines and passengers. There is a critical need for improving air traffic flow management. More importantly, aviation forecasters of airport should provide more timely and accurate information relating to dense fog to accommodate demands of different specific end users. However, the current situation is far from satisfactory. From a practical standpoint, some implications for dense fog forecasting are presented with the hope of improving the forecast of this phenomenon at the site. © 2015, Springer Science+Business Media Dordrecht. Source

Zhao Y.,Institute of Desert Meteorology | Fang Y.J.,Beijing Climate Center | Cui C.X.,Xinjiang Meteorological Observatory | Huang A.N.,Nanjing University
Journal of Arid Land

Soil moisture is an important parameter for the interaction between soil and atmosphere. It is the second important factor that influences climate change, next to sea surface temperature (SST). Most previous studies focused on the monsoon regions in East China, and only a few laid emphases on arid environments. In Xinjiang, which is located in Northwest China, the climate is typically arid and semi-arid. During the past 20 years, the precipitation in Xinjiang has shown a significant increasing trend, and it is closely related to oasis irrigation. This paper aims at discussing whether abnormal soil moisture in spring can be the signal to forecast summer precipitation. The effects of abnormal soil moisture due to farm irrigation in spring in arid environments on regional climate are investigated by using a regional climate model (RegCM3). The results indicate that positive soil moisture anomaly in irrigated cropland surface in May led to an increase in precipitation in spring as well as across the whole summer. The impact could last for about four months. The effects of soil moisture on the surface air temperature showed a time-lagging trend. The summer air temperature declined by a maximum amplitude of 0.8°C. The increased soil moisture could enhance evaporation and ascending motion in the low troposphere, which brought in more precipitation. The soil moisture affected regional weather and climate mainly by altering the surface sensible and latent heat fluxes. Source

Peng D.,Xinjiang Institute of Ecology and Geography | Peng D.,University of Chinese Academy of Sciences | Wang X.,Xinjiang Institute of Ecology and Geography | Wang X.,The Interdisciplinary Center | And 4 more authors.

There has been evidence of warming rate varying largely over space and between seasons. However, little has been done to evaluate the spatial and temporal variability of air temperature in the Tarim Basin, northwest China. In this study, we collected daily air temperature from 19 meteorological stations for the period of 1960-2012, and analyzed annual mean temperature (AMT), the annual minimum (Tmin) and maximum temperature (Tmax), and mean temperatures of all twelve months and four seasons and their anomalies. Trend analyses, standard deviation of the detrended anomaly (SDDA) and correlations were carried out to characterize the spatial and temporal variability of various mean air temperatures. Our data showed that increasing trend was much greater in the Tmin (0.55°C/10a) than in the AMT (0.25°C/10a) and Tmax (0.12°C/10a), and the fluctuation followed the same order. There were large spatial variations in the increasing trends of both AMT (from 20.09 to 0.43°C/10a) and Tmin (from 0.15 to 1.12°C/10a). Correlation analyses indicated that AMT had a significantly linear relationship with Tmin and the mean temperatures of four seasons. There were also pronounced changes in the monthly air temperature from November to March at decadal time scale. The seasonality (i.e., summer and winter difference) of air temperature was stronger during the period of 1960-1979 than over the recent three decades. Our preliminary analyses indicated that local environmental conditions (such as elevation) might be partly responsible for the spatial variability, and large scale climate phenomena might have influences on the temporal variability of air temperature in the Tarim Basin. In particular, there was a significant correlation between index of El Niño-Southern Oscillation (ENSO) and air temperature of May (P= 0.004), and between the index of Pacific Decadal Oscillation (PDO) and air temperature of July (P =0.026) over the interannual to decadal time scales. © 2014 Peng et al. Source

Mamat Z.,Xinjiang University | Halik U.,Xinjiang University | Halik U.,Catholic University of Eichstatt-Ingolstadt | Aji R.,Xinjiang Meteorological Observatory | And 3 more authors.
Chinese Journal of Applied Ecology

In this paper, we used land use/cover ecosystem service value estimation model and ecological economic coordination degree model to analyze the changes of the ecosystem service value by the land use/cover changes during 1985, 1990, 1996, 2000, 2005 and 2011 in Yanqi Basin, Xinjiang. Then we evaluated the ecology-economy harmony and the regional differences. The results showed that during 1985-2011, there was an increasing trend in the areas of waters, wetland, sand, cultivated land and construction land in Yanqi Basin. In contrast, that of the saline-alkali land, grassland and woodland areas exhibited a decreasing trend. The ecosystem service value in Yanqi Basin during this period presented an increasing trend, among which the waters and cultivated land contributed most to the total value of ecosystem services, while the grassland and the woodland had obviously declined contribution to the total value of ecosystem services. The research showed that the development of ecological economy in the study area was at a low conflict and low coordination level. So, taking reasonable and effective use of the regional waters and soil resources is the key element to maintain the ecosystem service function and sustainable and harmonious development of economy in Yanqi Basin. ©, 2015, Editorial Board of Chinese Journal of Applied Ecology. All right reserved. Source

Discover hidden collaborations