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15 November 2017, Volume 34 Issue 6 Previous Issue    Next Issue

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Spatio temporal Variation of the Days of Low Visibility in China during the Period from 1957 to 2015 KONG Feng,WANG Yifei,FANG Jiayi,LI Shuangshuang,FANG Jian,LV Lili,Shi Peijun,GUO Jianping 2017, 34 (6):  1203-1213.  doi: 10.13866/j.azr.2017.06.01 Abstract ( 847 )   PDF (3253KB) ( 593 )   Visibility reduction is an important feature of air pollution,which has its own distinct characteristics. There are significant differences in visibility among different cities. The meteorological data observed by 753 stations during the period of 1957-2015 and provided by National Meteorological Center of China Meteorological Administration were used to diagnose the spatiotemporal variation of visibility at different levels in China. Results showed that the days of visibility at level 1 and level 2 in the east of “Hu Huanyong Line” were in a significant decrease trend,those at level 0 in the same region were in an increase or a decrease trend,and the increase trend was dominant in the west; the change trend of days of visibility at level 3,4 and 5 was not significant at the most stations,and there was a decrease trend at a few stations. With the increase of visibility level,the stations with the decrease of days of visibility became less and less. The annual days of low visibility were on the rise. Temporally,the days of low visibility were on the rise and occurred in all seasons,and absolutely,their increase was the highest in winter but the lowest in summer,and their proportion was in an increase in summer and autumn. Spatially,the days of low visibility were increased from the east edge of croppingnomadic ecotone to the southeast coastal area,especially in winter,and the increase trend was not significant in summer. The time series correlation analysis revealed that there was a positive correlation between the days of low visibility in China and the total energy production,car ownership,urbanization rate,gross domestic product (GDP) and the second industry,which passed the test of 0.01 significance level. The spatial correlation analysis revealed that there was a high spatially negative correlation between the days of low visibility and the countylevel population density and average wind speed,which passed the test of 0.01 significance level. Therefore,the rapid urbanization and industrialization as well as the decrease of average wind speed may be the main causes of the significant increase of days of low visibility in China. References | Related Articles | Metrics

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Change of Stable Isotopes in Summer Precipitation in Central Inner Mongolia LI Wenbao,LI Changyou,JIA Debin,HAO Shiqi,LIU Zhijiao,LI Ruizhen 2017, 34 (6):  1214-1221.  doi: 10.13866/j.azr.2017.06.02 Abstract ( 727 )   PDF (1481KB) ( 591 )   Abstract：Stable isotopes in precipitation,such as δD and δ18O,are two important indicators of analyzing water vapor sources and transport pathways in rainfall process. The values of δD and δ18O can be used to analyze the factors affecting precipitation. In this paper,the samples of summer rainfall in Hohhot,Zhenglan Banner of Xilin Gol League and Dali Nor Lake in Hexigten Banner of Chifeng City,Inner Mongolia were collected. Based on the values of δD and δ18O in precipitation in the study areas,the characteristics of summer precipitation in central Inner Mongolia were discussed in detail. The results are as follows: ① The meteoric water lines over central Inner Mongolia were significantly different,which showed that the water vapor sources were different. The slope and intercept of meteoric water line over Baotou City were both lower,and their values were 5.84 and -8.88 respectively. Correspondingly,the slope and intercept of meteoric water line over the Dali Nor Lake were both higher,and their values were 8.26 and 7.21 respectively,which was similar to the global or Chinese meteoric water line; ② The change of δD and δ18O was mainly affected by the process of rainfall and local evaporation. Meanwhile,the value of deuterium surplus parameter (d) was also different from different months in summer. As a whole,the precipitation intensity and local evaporation might be the main factors affecting the change of d value. The proportion of precipitation in July was higher than that in other three months in summer,which could lead to the lowest d value in July,and also showed that the precipitation intensity might have stronger influence on the change of d value than the local evaporation in July. The d value was high in June and September,which revealed that the local evaporation might have stronger influence on process of rainfall. References | Related Articles | Metrics

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Identification of Soil Water Migration and Recharge Sources in The Southern Marginal Zone of the Junggar Basin, China SUN Fangqiang,YIN Lihe,MA Hongyun,ZHANG Jun,WANG Xiaoyong,DONG Jiaqiu,HE Shuaijun 2017, 34 (6):  1271-1277.  doi: 10.13866/j.azr.2017.06.08 Abstract ( 1070 )   PDF (1526KB) ( 493 )   Abstract：Soil water is the basis of all terrestrial plants in desert area. Investigation on the migration patterns of soil water is necessary for identifying the recharge sources of soil water and for the ecological regeneration in desert area. In this paper, the origin and migration patterns of soil water in a desert area in the southern marginal zone of the Junggar Basin were investigated based on measuring soil moisture content, stable isotopes (δD and δ18O) of soil water and soluble salt ions. The results indicated that the vertical profiles of stable isotopes, water content and soluble salt ions of soil water were in a cyclic variation. The Cl- composition in soil was positively correlated to soil moisture content. The influencing depth of evaporation was 0-1.6 m; soil water in a deep range of 1.6-8.0 m moved downward, and soil water below 8.0 m was influenced by groundwater. The vertical variations of stable isotopes and Cl- composition in soil water indicated that soil water originated from precipitation in desert area. The low values of Cl- composition corresponded to the depleted values of δD and δ18O; δD of soil water varied from -124.10‰ to -97.39‰, which suggested that soil water originated from precipitation or snow melt winter. References | Related Articles | Metrics

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Variation of Soil Enzyme Activity among Four Typical Plant Communities in the Ebinur Lake Wetland Nature Reserve,Xinjiang YANG Xiaodong,LV Guanghui,HE Xueming,LI Yan,ZHANG Xueni,WANG Xiyuan,LIU Weiguo 2017, 34 (6):  1278-1285.  doi: 10.13866/j.azr.2017.06.09 Abstract ( 954 )   PDF (1132KB) ( 466 )   Abstract：Soil enzyme is an important driving force for metabolic process of soil ecosystem,its change among soil layers and among plant communities can help us to understand the material cycle and energy conversion of soil ecosystem. In this study,four typical plant communities,i.e.Populus euphratica,Haloxylon persicum,Tamarix chinensis and [WTBX]Halocnemum strobilaceum communities,were set as the research subjects,and subsequently the variations of soil enzyme activities,i.e. catalase,urease,phosphatase and invertase,and the soil physicochemical properties and community quantity characteristics were investigated so as to reveal the relationships among them. The results are as follows: ① Soil enzyme activities were not significantly different among soil layers of 0-15,15-30 and 30-50 cm in depth in the four typical communities (P>0.05); ② There were no significant changes of activities of catalase and phosphatase among the four typical communities at the same soil depth (P>0.05), whereas the urease and invertase activities were opposite (P<0.05); ③ The results of multivariate linear stepwise regression revealed that there were little relations between the activities and community quantity characteristics for other soil enzymes except for the variation of catalase activity influenced by community quantity characteristics. In conclusion,soil physicochemical properties and community quantity characteristics can affect the changes of soil enzymes activity across soil layers and plant communities,however,the essential factors affecting soil enzyme activity was related to soil type. References | Related Articles | Metrics

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Effect of Soil Microbiotic Crust on Plant Community in the Gurbantunggut Desert ZHUANG Weiwei,ZHANG Yuanming 2017, 34 (6):  1338-1344.  doi: 10.13866/j.azr.2017.06.16 Abstract ( 921 )   PDF (1046KB) ( 631 )   Abstract：The plant communities in the microbiotic crustintact and microbiotic crustremoved plots in the Gurbantonggut Desert were investigated. The desert is mosaicspatched by vascular plants and soil microbiotic crust. The influence of soil microbiotic crust on seed germination,seedling survival,soil nutrient content and water distribution was firstly discussed,and then the influence of soil microbiotic crust on plant diversity was studied. The results showed that the sum of the biomass of five dominant herb species including Erodium oxyrrhynchum,Alyssum linifolium,Hyalea pulchella,Alyssum desertorum and Eremopyrum triticeum contributed more than 90% of the total aboveground biomass of the synusia. Compared with the microbiotic crustintact plot,the plant height,Shannon Wiener diversity index (H) and species richness (R) were significantly increased after the microbiotic crust was removed. However,the plant density,productivity and coverage were lower than those in microbiotic crustintact plot. These results indicated that the diversity and coverage of herbaceous plants were significantly affected by microbiotic crust. It is concluded that microbiotic crust could promote the restoration of desert ecosystem. References | Related Articles | Metrics

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Flood Prediction Models and Their Application for the Medium and Small Rivers in Alpine Area in Xinjiang CHEN Xinchi,ZHANG Liping,SHAN Lijie,YANG Wei,JIA Junwei 2017, 34 (6):  1426-1435.  doi: 10.13866/j.azr.2017.06.27 Abstract ( 891 )   PDF (6464KB) ( 517 )   Abstract：Commonly low standards of flood control for medium and small rivers and frequently occurred flood disaster usually lead to extremely serious economic loss in China. Two typical medium and small rivers, the Jingou River and Kuytun River in alpine areas in Xinjiang, were selected in this study. Based on snowmelt runoff model, stepwise multivariate regression and nearest neighbor bootstrap regression, the daily runoff volumes of the two catchments were simulated after collecting the hydrological data, meteorological data and the snow cover data extracted from MODIS remote sensing imags. The results showed that the three models could be used to well simulate the runoff process of the Jingou River and Kuytun River catchments, Nash efficiency coefficients in both calibration and validation periods were higher than 0.7, and each model had its own advantages and disadvantages, which means that the snowmelt runoff model, stepwise multivariate regression and nearest neighbor bootstrap regression could be applied to predict flood in the Jingou River and Kuytun River catchments. The study results are of some guiding significance for preventing and earlywarning flood of the medium and small rivers in alpine area. References | Related Articles | Metrics