Sand and dust storms (SDS) are common phenomena in arid and semi-arid areas. In recent years, SDS frequencies and intensities have increased significantly in Iran. A research on SDS sources is important for understanding the mechanisms of dust generation and assessing its socio-economic and environmental impacts. In this paper, we developed a new approach to identify SDS source areas in Iran using a combination of nine related datasets, namely drought events, temperature, precipitation, location of sandy soils, SDS frequency, human-induced soil degradation (HISD), human influence index (HII), rain use efficiency (RUE) and net primary productivity (NPP) loss. To identify SDS source areas, we firstly normalized these datasets under uniform criteria including layer reprojection using Lambert conformal conic projection, data conversion from shapefile to raster, Min-Max Normalization with data range from 0 to 1, and data interpolation by Kriging and images resampling (resolution of 1 km). After that, a score map for the possibility of SDS sources was generated through overlaying multiple datasets under average weight allocation criterion, in which each item obtained weight equally. In the score map, the higher the score, the more possible a specific area could be regarded as SDS source area. Exceptions mostly came from large cities, like Tehran and Isfahan. As a result, final SDS source areas were mapped out, and Al-Howizeh/Al-Azim marshes and Sistan Basin were identified as main SDS source areas in Iran. The SDS source area in Al-Howizeh/Al-Azim marshes still keeps expanding. In addition, Al-Howizeh/Al-Azim marshes are now suffering rapid land degradation due to natural and human-induced factors and might totally vanish in the near future. Sistan Basin also demonstrates the impacts of soil degradation and wind erosion. With appropriate intensity, duration, wind speed and altitude of the dust storms, sand particles uplifting from this area might have developed into extreme dust storms, especially during the summer.

The Badain Jaran Desert is the second-largest area of shifting sands in China. Our first measurements of the energy components and water vapor fluxes on a megadune using eddy covariance technology were taken from April 2012 to April 2013. The results indicate that the longwave and shortwave radiative fluxes exhibited large fluctuations and seasonal dynamics. The total radiative energy loss by longwave and shortwave radiation was greater on the megadune than from other underlying surfaces. The radiation partitioning was different in different seasons. The land-atmosphere interaction was primarily represented by the sensible heat flux. The average sensible heat flux (40.1 W/m²) was much larger than the average latent heat flux (14.5 W/m²). Soil heat flux played an important role in the energy balance. The mean actual evaporation was 0.41 mm/d, and the cumulative actual evaporation was approximately 150 mm/a. The water vapor would transport downwardly and appear as dew condensation water. The amount of precipitation determined the actual evaporation. The actual evaporation was supposed to be equal to the precipitation on the megadune and the precipitation was difficult to recharge the groundwater. Our study can provide a foundation for further research on land-atmosphere interactions in this area.

Wind and water erosion are among the most important causes of soil loss, and understanding their interactions is important for estimating soil quality and environmental impacts in regions where both types of erosion occur. We used a wind tunnel and simulated rainfall to study sediment yield, particle-size distribution and the fractal dimension of the sediment particles under wind and water erosion. The experiment was conducted with wind erosion firstly and water erosion thereafter, under three wind speeds (0, 11 and 14 m/s) and three rainfall intensities (60, 80 and 100 mm/h). The results showed that the sediment yield was positively correlated with wind speed and rainfall intensity (P<0.01). Wind erosion exacerbated water erosion and increased sediment yield by 7.25%–38.97% relative to the absence of wind erosion. Wind erosion changed the sediment particle distribution by influencing the micro-topography of the sloping land surface. The clay, silt and sand contents of eroded sediment were also positively correlated with wind speed and rainfall intensity (P<0.01). Wind erosion increased clay and silt contents by 0.35%–19.60% and 5.80%–21.10%, respectively, and decreased sand content by 2.40%–8.33%, relative to the absence of wind erosion. The effect of wind erosion on sediment particles became weaker with increasing rainfall intensities, which was consistent with the variation in sediment yield. However, particle-size distribution was not closely correlated with sediment yield (P>0.05). The fractal dimension of the sediment particles was significantly different under different intensities of water erosion (P<0.05), but no significant difference was found under wind and water erosion. The findings reported in this study implicated that both water and wind erosion should be controlled to reduce their intensifying effects, and the controlling of wind erosion could significantly reduce water erosion in this wind-water erosion crisscross region.

Although scientists have performed many studies in the Taklimakan Desert, few of them have reported the blown sand motion along the southern edge of the Taklimakan Desert Highway, which differs significantly from the northern region in terms of aeolian sand geomorphology and formation environment. Based on the field observation data of airflow and aeolian sand transport, continuous monitoring data of erosional and depositional processes between 14 April 2009 and 9 April 2011 and data of surface sand grains from the classical section along the southern edge of the Taklimakan Desert Highway, this paper reported the blown sand motion within the sand-control system of the highway. The main results are as follows: 1) The existing sand-control system is highly effective in preventing and controlling desertification. Wind velocities within the sand-control system were approximately 33%–100% of those for the same height above the mobile sand surface. Aeolian sand fluxes were approximately 0–31.21% of those of the mobile sand surface. Sand grains inside the system, with a mean diameter of 2.89 φ, were finer than those (2.15 φ) outside the system. In addition, wind velocities basically followed a logarithmic law, but the airflow along the classical section was mainly determined by topography and vegetation. 2) There were obvious erosional and depositional phenomena above the surface within the sand-control system, and these phenomena have very consistent patterns for all observation points in the two observed years. The total thicknesses of erosion and deposition ranged from 0.30 to 14.60 cm, with a mean value of 3.67 cm. In contrast, the deposition thicknesses were 1.90–22.10 cm, with a mean value of 7.59 cm, and the erosion thicknesses were 3.51–15.10 cm, with a mean value of 8.75 cm. The results will aid our understanding of blown sand within the sand-control system and provide a strong foundation for optimizing the sand-control system.

Chemical records from alpine ice cores provide an invaluable source of paleoclimatic and environ-mental information. Not only the atmospheric chemical composition but also depositional and post-depositional processes are recorded within snow/firn strata. To interpret the environmental and climatic significance of ice core records, we studied the variability of glacier snowpack chemistry by investigating homogeneous snowpacks from October 2003 to September 2006 on Urumqi Glacier No. 1 in eastern Tianshan Mountains, Central Asia. Principle Component Analysis of ionic species in dry and wet seasons revealed the impact of meltwater in redistributing ions in the snowpacks. The 1^st, 2^nd and 3^rd principle components for dry seasons differ significantly, reflecting complex associations between depositional or/and post-depositional processes. The variability trend of ionic concentrations during the wet seasons was found to fit a Gauss Function with significant parameters. The elution factor revealed that more than half of ions are leached out during the wet seasons. Differences with respect to ion snowpack mo-bility were found. Of the ions studied SO₄^2– was the most mobile and Mg²⁺ the least mobile. A threshold relationship between air temperatures and the elution process was investigated over the study period. The results indicate that the strong melt /ablation processes and iconic redistribution occur at a threshold air temperature of 0°C. The study found that surface melt on the snowpacks is the main factor causing the alteration of the snowpack chemistry. Rainfall also has an impact on the chemistry but plays a less significant role than the surface melt.

Stable isotopic compositions (δ¹⁸O and δD) have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationship between the stable isotopic contents in lake water and the variations of lake level, particularly in Lake Qinghai, China. In this study, we analyzed the variations of isotope compositions (δ¹⁸O, δD and d-excess) in lake water and precipitation by using the samples that were collected from Lake Qinghai region during the period from 2009 to 2012. The results showed that the average isotopic contents of δ¹⁸O and δD in lake water were higher than those in precipitation, which were contrary to the variations of d-excess. The linear regression correlations between δ¹⁸O and δD in lake water and precipitation showed that the local evaporative line (LEL) in lake water (δD=5.88δ¹⁸O–2.41) deviated significantly from the local meteoric water line (LMWL) in precipitation (δD=8.26δ¹⁸O+16.91), indicating that evaporative enrichment had a significant impact on isotopic contents in lake water. Moreover, we also quantified the E/I ratio (evaporation-to-input ratio) in Lake Qinghai based on the lake water isotopic enrichment model derived from the Rayleigh equation. The changes of E/I ratios (ranging from 0.29 to 0.36 between 2009 and 2012) clearly revealed the shifts of lake levels in Lake Qinghai in recent years. The average E/I ratio of 0.40 reflected that water budget in Lake Qinghai was positive, and consistent with the rising lake levels and the increasing lake areas in many lakes of the Tibetan Plateau. These findings provide some evidences for studying the hydrological balance or water budget by using δ¹⁸O values of lake sedimentary materials and contribute to the reconstruction of paleolake water level and paleoclimate from an isotopic enrichment model in Lake Qinghai.

Soil labile organic carbon (C) plays an important role in improving soil quality. The relatively stable fractions of soil organic C (SOC) represent the bulk of SOC, and are also the primary determinant of the long-term C balance of terrestrial ecosystems. Different land use types can influence the distribution patterns of different SOC fractions. However, the underlying mechanisms are not well understood. In the present study, different fractions of SOC were determined in two land use types: a grazed grassland (established on previously cultivated cropland 25 years ago, GG) and a long-term cultivated millet cropland (MC). The results showed that C concentration and C storage of light fractions (LF) and heavy fractions (HF) presented different patterns along the soil profiles in the two sites. More plant residues in GG resulted in 91.9% higher LF storage at the 0–10 cm soil depth, further contributed to 21.9% higher SOC storage at this soil depth; SOC storage at 20–60 cm soil depth in MC was 98.8% higher than that in GG, which could be mainly attributed to the HF storage 104.5% higher than in GG. This might be caused by the long-term application of organic manure, as well as the protection from plough pan and silt- and clay-sized particles. The study indicated that different soil management practices in this region can greatly influence the vari-ations of different SOC fractions, while the conventional tillage can greatly improve the storage of SOC by in-creasing heavy fractions.

The biological and chemical conditions of the rhizosphere are known to considerably differ from those of the bulk soil, as a consequence of a range of processes that are induced either directly by the activity of plant roots or indirectly by the stimulation of microbial population and activity in the rhizosphere. Information about phosphorus (P) fractionation in the rhizosphere soils amended with municipal sewage sludge (MSS) is limited. were We carried out greenhouse experiments using a rhizobox in order to evaluate the effects of bean rhizosphere on the various inorganic P (Pi) fractions, organic P (Po), P in particulate fraction (PF-P), Olsen-P, dissolved organic C (DOC), microbial biomass P (MBP) and alkaline phosphatase (ALP) enzyme in 10 calcareous soils amended with MSS (10 g MSS was added to 1 kg soil). Non-occluded P, occluded P, calcium phosphate and residual P were also quantitated. The results showed that DOC, MBP and ALP activity strongly increased and PF-P and Olsen-P de-creased in the rhizosphere soils compared with in the bulk soils (P<0.05). The contents of non-occluded P, oc-cluded P and residual-P fractions in the rhizosphere soils were lower than in the bulk soils, while the contents of calcium phosphate and organic P in the rhizosphere soils were higher than in the bulk soils. Simple correlation coefficients showed that P uptake had positive relationship with non-occluded P, occluded P, calcium phosphate fractions and PF-P in the rhizosphere soils. The results suggest that the short-term application of MSS to the cal-careous soils may increase Po and calcium phosphate fractions in the rhizosphere soils, and calcium phosphate fraction is potentially available to crops.

 Human-environment relationship is a focus of academic researches and an understanding of the rela-tionship is important for making effective policies and decisions. In this study, based on rural household survey data of Taibus Banner, Duolun county and Zhengxiangbai Banner in the Inner Mongolia autonomous region of China, we identified the impact of livelihood diversification on ecosystems in these agro-pastoral areas by using the ecological footprint theory and methodology together with the one-way analysis of variance (ANOVA) and correlation analysis methods. In 2011, the total ecological footprint of consumption (EFC) was 0.665 g hm2, and the total ecological footprint of production (EFP) was 2.045 g hm2, which was more than three times the EFC. The ecological footprint of arable land consumption (EFAC) accounted for a large proportion of the EFC, and the ecological footprint of grassland production (EFGP) occupied a large proportion of the EFP. Both the ecological footprint of grassland consumption (EFGC) and EFGP had a significant positive correlation with the income, indicating that income was mainly depended on livestock production and the households with higher incomes consumed more livestock prod-ucts. The full-time farming households (FTFHs) had the highest EFP, ecological footprint of arable land production (EFAP), EFGP and EFGC, followed by the part-time farming households (PTFHs) and non-farming households (NFHs), which indicated that part-time farming and non-farming employment reduced the occupancy and con-sumption of rural households on local ecosystems and natural resources to some extent. When farming households engaged in livestock rearing, both the EFAP and EFAC became smaller, while the EFP, EFC, EFGC and EFGP increased significantly. The differences in ecological footprints among different household groups should be taken into account when making ecosystem conservation policies. Encouraging the laborers who have the advantages of participating in non-farming employment to move out of the rural areas and increasing the diversification of liveli-hoods of rural households are important in reducing the environmental pressures and improving the welfare of households in the study area. Moreover, grassland should be utilized more effectively in the future.

Nighttime sap flow is a potentially important factor that affects whole-plant water balance and water-use efficiency (WUE). Its functions include predawn disequilibrium between plant and soil water potentials as well as between the increments of oxygen supply and nutrient uptake. However, main factors that drive nighttime sap flow remain unclear, and researches related to the relationship between nighttime sap flow velocity and environmental factors are limited. Accordingly, we investigated the variations in the nighttime sap flow of Populus euphratica in a desert riparian forest of an extremely arid region, Northwest China. Results indicated that P. euphratica sap flow occurred throughout the night during the growing season because of the partial stomata opening. Nighttime sap flow for the P. euphratica forest accounted for 31%–47% of its daily sap flow during the growing season. The high value of nighttime sap flow could be the result of high stomatal conductance and could have significant implications for water budgets. Throughout the whole growing season, nighttime sap flow velocity of P. euphratica was positively correlated with the vapor pressure deficit (VPD), air temperature and soil water content. We found that VPD and soil water content were the main driving factors for nighttime sap flow of P. euphratica.

The present research was undertaken to explor the possibility of arbuscular mycorrhizal (AM) associa-tion with Asteraceae plants in the arid lands of Saudi Arabia (Al-Ghat, Buraydah, Thumamah and Huraymila). AM fungal colonization in the roots, spore numbers in the rhizosphere soil, fungal species diversity and correlation between AM properties and soil properties were determined. The highest colonization was in Conyza bonariensis (65%) from Al-Ghat, Anthemis cotula (52%) from Buraydah and C. bonariensis (53%) from Thumamah. The lowest was in Vernonia schimperi (41%) from Al-Ghat, Pulicaria undulata (25%) from Buraydah, Acanthospermum hispidum (34%) from Thumamah, Asteriscus graveolens (22%) and V. schimperi (22%) from Huraymila. Vesicular and arbuscular colonization were also presented in all plant species examined. The number of spores were 112–207 in Al-Ghat, 113–133 in Buraydah, 87–148 in Thumamah and 107–158 in Huraymila. Funneliformis mosseae, Glomus etunicatum, G. fasciculatum and G. aggregatum were identified. Relative frequency of AM fungal species varied widely and was irrespective of location and plant species. Diversity index varied with the rhizosphere soils of dif-ferent plant species at various locations. Soil properties varied with locations and no distinct correlations were ob-served among the soil properties, root colonization and the number of spores. The results of the present study specified the association of AM fungi in different plants of Asteraceae and its significance in the ecological func-tioning of annual plants in the punitive environments of the rangelands in Saudi Arabia.

The amount and the form of precipitation have significant effects on glacier mass balances in high al-titude mountain areas by controlling the accumulation, the ablation and the energy balance of a glacier through impact on the surface albedo. The liquid precipitation has negative effects on glacier accumulation and may in-crease the ablation of surface ice through the heat input for melting. The timing and the forms of precipitation over glacierized regions depend on the weather processes both locally and regionally. Early studies showed that regional to large-scale atmospheric circulation processes play a key role in affecting the precipitation events over glaciers. This paper analyzed the relationship between the inter-annual variability of the summertime precipitation over the Tuyuksu Glacier and the atmospheric circulation types, which related to various atmospheric circulation types in the Northern Hemisphere. Results indicated that the decrease in the duration of zonal processes and the increase in the meridional northern processes were observed in the last decade. The total summer precipitation associated with these processes also increased along with an increase of summertime solid precipitation. Although the decadal fluctuation of glaciological parameters were found in dependent of the above large-scale atmospheric circulation processes, global warming was a dominant factor leading to the mass loss in the recent decades under the back-ground of the increase in precipitation over the Tuyuksu Glacier.

Soil salinization is a major concern for agricultural development in arid areas. In this paper, a modified Dobson dielectric model was applied to simulate the dielectric constant of saline soil in the Ugan-Kuqa river delta oasis of Xinjiang Uygur autonomous region, northwestern China. The model performance was examined through analyzing the influences of its parameters on the soil dielectric constant and the relationship between radar back-scattering coefficient and the dielectric constant of saline soil. The results of the study indicate that: (1) The real part of the soil dielectric constant is affected by soil water content at low radar frequencies; the imaginary part is closely related with both the soil water content and soil salt content. (2) The soil water and salt contents are related with the coefficient of dialectical loss, which is consistent with the natural conditions of saline soil in arid areas and provides valuable references for the study of soil dielectric properties. (3) The changes of soil water content and soil salt content have instant influences on the dielectric constant of saline soil. Subsequently, the radar backscattering coefficient is affected to respond to the dielectric constant of saline soil. The radar backscattering coefficient is most responsible to the radar’s cross polarization pattern with a correlation coefficient of R²=0.75. This study provides a potential method to monitor soil salinization and soil water content by using a soil dielectric model and radar tech-niques.

Fossil energy is the material basis of human survival, economic development and social progress. The relationship between energy consumption and economic growth is becoming increasingly close. However, energy consumption is the major source of greenhouse gases, which can significantly affect the balance of the global ecosystem. It has become the common goal of countries worldwide to address climate change, reduce carbon dioxide emissions, and implement sustainable development strategies. In this study, we applied an approximate relationship analysis, a decoupling relationship analysis, and a trend analysis to explore the relationship between energy consumption and economic growth using data from Kazakhstan for the period of 1993–2010. The results demonstrated: (1) the total energy consumption and GDP in Kazakhstan showed a ”U”-type curve from 1993 to 2010. This curve was observed because 1993–1999 was a period during which Kazakhstan transitioned from a republic to an independent country and experienced a difficult transition from a planned to a market economy. Then, the economic system became more stable and the industrial production increased rapidly because of the effective financial, monetary and industrial policy support from 2000 to 2010. (2) The relationships between energy consumption and carbon emissions, economic growth and energy exports were linked; the carbon emissions were mainly derived from energy consumption, and the dependence of economic growth on energy exports gradually increased from 1993 to 2010. Before 2000, the relationship between energy consumption and economic growth was in a recessional decoupling state because of the economic recession. After 2000, this relationship was in strong and weak decoupling states because the international crude oil prices rose and energy exports increased greatly year by year. (3) It is forecasted that Kazakhstan cannot achieve its goal of energy consumption by 2020. Therefore, a low-carbon economy is the best strategic choice to address climate change from a global perspective in Kazakhstan. Thus, we proposed strategies including the improvement of the energy consumption structure, the development of new energy and renewable energy, the use of cleaner production technologies, the adjustment and optimization of the industrial structure, and the expansion of forest areas.