Jinglong Fan

Characteristics of the soil microbial population in forest land irrigated with saline water in the desert area

The study of soil microbial populations and diversity is an important way to understanding the soil energy process.In this study we analyzed the characteristics of soil microbial populations of the Tarim Desert Highway shelter-forest,by identifying microbial fatty acids and using methods of conventional cul-tivation.The results illustrated that the amount of soil microbial activity and the diversity of soil microbial fatty acid increased significantly with the plantation age of the shelter-forest;the soil microbial population was dominated by bacteria.The fatty acids of C14︰0,C15︰0,C16︰0,C17︰0,C18︰1ω9,C18︰0,C18︰2ω6 and C21︰0 were found to be dominant soil microbial fatty acids in the shelter-forest soil.Prin-cipal analysis and regression analysis showed that(1) concentrations of fatty acids of C14︰0,C16︰0 and C18︰0 could be used as indicators of total soil microbial population;(2) soil bacteria and actinomycetes populations were closely correlated with the amount of fatty acids of C15︰0 and C17︰0;and(3) soil fungi were closely correlated with the amount of fatty acids of C18︰1ω9 and C18︰2ω6.

Comparative Analysis of Reference Crop Evapotranspiration and Pan Evaporation of Taklimakan Desert Hinterland

Using the meteorological data of Taklimakan Desert Hinterland from 2005 to 2010, reference crop evapotranspiration (ET0) of extreme arid region of Taklimakan Desert Hinterland was calculated with FAO Penman-monteith calculation method, and the comparative analysis was conducted with pan evaporation (Ø20) in the meteorological station, the influencing factors that had an effect on ET0 and Ø20 meteorological factors were sequenced with the grey association degree analysis theory. The results were shown that ET0 maximum value appeared in July, and the minimum value appeared in January; Ø20 maximum value appeared in June, and the minimum value appeared in December; monthly potential reference crop evapotranspiration coefficients ranged between 0.30 and 0.46. Grey correlation analysis showed that the meteorological factors that were most closely relationship with ET0 was Umean, second was Tmax, while the meteorological factors that was most closely relationship with Ø20 was Tmax, second was Umean. The meteorological factors that affected ET0 and Ø20 were different in the Spring, summer, autumn and winter, and the biggest difference between them appeared in summer. ET0 presented highly significant linear relationship with Ø20 in spring, autumn and winter, while there was significant linear relationship in summer. The research results could provide theoretical support for the rational use of water resources and the sustainable development of Tarim desert highway shelterbelt.

Chemical Characteristics and Evolution Simulation of Shallow Groundwater in the Taklimakan Desert

The chemistry data of shallow groundwater round was obtained through positional observation section at Luntai-Tazhong-Minfeng in the Taklimakan desert and the main chemistry indicators of groundwater were carried out system analysis. The relationship between the major ions and TDS in the desert shallow groundwater was clarified by using descriptive statistical methods and correlation coefficient methods. The spatial distribution characteristics of the groundwater TDS and pH were discussed by using the graphical method. The cross-section groundwater chemistry types and their spatial distribution were also studied by using Piper graphical method. the hydrogeochemistry simulation was carried out by using hydrogeochemical NETPATH interactive program, and the process of chemical evolution of desert shallow groundwater and its laws were also discussed. The results were shown that the TDS in desert shallow groundwater was relatively high, its value ranged between 30.246 ~ 3.093 g/L. The spatial distribution characteristics were high in the north and lower in the south, and the south was slightly higher than central region. Groundwater chemical type was mainly Na-Mg-Cl-SO4 and Na-Cl-SO4 type. NETPATH simulation results showed that with the diminishing sources of minerals, there was a decreasing trend of the amount of Water rock reaction products from upstream to downstream of ground water flow, the increased ion concentration in the downstream was due to the continual influence of leaching and evaporation factors. Rock salt in groundwater was always in solution, but the calcite was always in precipitation state, so that decreased the concentration of HCO3-, the mirabilite was dissolved to provide enough SO42-; the amount of orthoclase that took part in the reaction was very small, while muscovite mainly generated precipitation, thus the content of K+ in the groundwater is extremely low. These processes could make the groundwater ultimately evolve into the Na-Cl-SO4 type, and gradually formed the hypersalinity salt groundwater in the downstream region.

Groundwater Response to Pumping Process of Tarim Desert Highway Shelter Forest Project

In order to study the influence process of pumping on the groundwater in shelter forest project in the extremely arid desert regions, and provide a theoretical basis for sustainable maintenance and management of Tarim Desert Highway Shelter Forest Ecological Project, in this paper, through the observation field that was located in No.69 irrigation water source well in the Tarim Desert Highway Shelter Forest Ecological Project, the changes of water level and salinity in the well were observed in two pumping stress periods during the pumping process of water source well, and the hydrogeological parameters were determined by using Neuman model, as well as the changing regularity of water level in the pumping process was also analyzed. The studies had shown that in the two pumping stress periods, the rapid decline and rise process of water level could be completed within 11min after the start, and then changed into the slowly changing phase; after the pumping being stopped, the water level could be restored to the level before pumping, and did not cause the consecutive drops of natural groundwater level.