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Zhu B.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Zhu B.,CAS Institute of Geology and Geophysics | Yang X.,CAS Institute of Geology and Geophysics | Rioual P.,CAS Institute of Geology and Geophysics | And 4 more authors.
Applied Geochemistry | Year: 2011

In the arid region of northern Xinjiang, one of the least-studied areas in China, three watersheds, namely those of the Yili, Zhungarer and Erlqis, have become the focus of attention due to rapidly increasing human population and water demands. The hydrogeochemistry of natural water from the three watersheds was investigated. The ionic chemistry of natural waters from these watersheds changes considerably on a regional scale. The waters are neutral to alkaline in nature and most of them are soft-fresh waters. The total dissolved solid (TDS) varies over two orders of magnitude with a mean value of 580. mg/L, about 1.2 times and 4.6 times those of the Huanghe (Yellow River) and the world spatial median, respectively, but only 40% and 0.8% of those of the Tarim and the western Alashan watersheds, respectively. Much of the solutes and physicochemical parameters in these waters are under the highest desirable limits of the World Health Organization (WHO) for drinking purpose and a plot of sodium adsorption ratio versus EC shows that most waters are of good water quality for irrigation. Water-rock interaction and saturation index (SI) for selected minerals are evaluated. The SI of these natural waters is out of equilibrium (undersaturated) with respect to major carbonates (calcite and dolomite) and evaporites (gypsum and halite). The high concentrations of alkali earth metals, alkalinity and the high (Ca. +. Mg)/(Na. +. K) and Na/Cl ratios indicate that the release of major solutes in these waters is controlled largely by dissolution processes of carbonate and partly by silicate weathering, while, cation exchange reactions, soil-salt leaching and evaporation processes also play an important role. The effects of local pollution are minimal in the montane and piedmont areas of these watersheds but are significant in the oases and central areas of the drainage basins. © 2011 Elsevier Ltd.


Zhu B.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Yu J.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Qin X.,CAS Institute of Geology and Geophysics | Rioual P.,CAS Institute of Geology and Geophysics | Xiong H.,Key Laboratory of Oasis Ecology
Geomorphology | Year: 2012

A natural water hydrochemical investigation was carried out on three watersheds in northern Xinjiang, China to evaluate the climatic, geological and anthropogenic influence on aqueous major element chemistry in an arid environment. Wide spatial variations are observed in the dissolved solids (TDS) and water chemistry. The hydrochemistry is typically carbonate and alkaline in nature, with Ca 2+, HCO 3 - and SO 4 2- dominating the major ion composition. Four major water types, Ca-HCO 3, Ca-NDA (non-dominant anion), Ca-SO 4 and NDC (non-dominant cation)-NDA or Na-NDA type, are identified in terms of the Piper model. The water chemistry agrees well with the "rock dominance" mechanism, with a TDS value of 80-600mg/L and a Na +/(Na ++Ca 2+) ratio of 0.1-0.6. Correlation analysis suggests that most of the ions derive from multiple sources. Stoichiometric analyses indicate that carbonate weathering is the primary source of dissolved ions, followed by silicate weathering and evaporite dissolution. The effects of local pollution have somewhat greater contribution on the oases and central areas of the Zhungarer watershed. Most parts of the rivers show an increasing trend in the dissolved load toward the lower reaches, which is primarily attributed to an evaporation process control along the water course. Variations in water chemistry show clear correlation with the regional lithological distribution, topography and atmospheric precipitation. Using rainwater as a baseline, contributions from atmospheric precipitation and rock weathering to the tributary chemistry are roughly evaluated to be in the range of 2-39% (average 13%) and 59-98% (average 86%), respectively, implying a high effective control of regional geology on stream chemistry compared with that of atmospheric input. © 2012 Elsevier B.V.


Zhu B.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Zhu B.,CAS Institute of Geology and Geophysics | Yang X.,CAS Institute of Geology and Geophysics | Liu Z.,CAS Institute of Geology and Geophysics | And 3 more authors.
Environmental Earth Sciences | Year: 2012

Two large sandy seas in northern China, the Taklamakan and Badanjilin deserts, were investigated for geochemical variations of soluble salts in aeolian sands. The aim was to explore factors influencing the composition and distribution of soluble salts in aeolian sands and their environmental implications. The total concentrations of soluble salt in the aeolian sands range between 0.14 and 1.32‰, with pH ranging between 8.4 and 9.6, indicating a primary degree of salt accumulation and alkaline soil conditions in these regions. Sodium chloride and bicarbonate are the major salts. High inter-regional homogenization and small local differences in the chemical compositions and distributional patterns of salt occur in the two deserts. The spatial variations in salt content correlate with regional climatic parameters, such as precipitation and temperature. This suggests that the regional air temperature and moisture conditions of climate have a significant influence on the soluble salts in aeolian sands. The domination of sedimentation of soluble salts in aeolian sands deposited via atmospheric processes, which is heavily associated with dry deposition, is discussed. Case studies from the two deserts suggest that variations in salt content in sedimentary sequences, interlaid by aeolian and lacustrine sediments, should be interpreted with care if the aim is to reveal palaeo-environmental changes. To a certain extent, the two deserts, as inferred from the carbon-bearing salts and the alkalinity of the sandy soils, appear to have potential to provide a significant contribution to the global carbon cycle. © 2011 Springer-Verlag.


Zhu B.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Yu J.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Qin X.,CAS Institute of Geology and Geophysics | Rioual P.,CAS Institute of Geology and Geophysics | And 7 more authors.
Journal of Hydrology | Year: 2013

Rivers draining the sedimentary platform of northern Xinjiang (the center of Asian continent) are characterized by low discharge under a temperate and arid climate. The influence of rock mineralogy, climate, relief and human activity on natural water composition and export as a result of weathering is a major scientific concern both at the local and the global scale. While comprehensive work on the controlling mechanism of chemical weathering has been less carried out in the sedimentary platform of northern Xinjiang. Thus, the effects of climate and rock weathering on the inorganic hydrogeochemical processes are not well quantified at this climatic extreme. To remedy this lack a comprehensive survey has been carried out of the geochemistry of the large, pristine rivers in northern Xinjiang, the Erlqis, Yili, Wulungu, Jingou and numerous lesser streams which has not experienced the pervasive effects of glaciation and subsequent anthropogenic impacts. The scale of the terrain sampled, in terms of area, is comparable to that of the Huanghe and includes a diverse range of geologic and climatic environments. In this paper the chemical fluxes from the stable sedimentary basin of the northern Xinjiang platform will be presented and compared to published results from analogous terrains in the monsoon basins of China and world. Overall, the fluvial geochemistry of northern Xinjiang in westerly climate is similar to that of the Chinese rivers (Huanghe and Yangtze) in the East-Asian monsoon Climate, both in property-property relationships and concentration magnitudes. The range in the chemical signatures of the various tributaries is large; this reflects that lithology exerts the dominant influence in determining the weathering yield from the sedimentary terrains rather than the weathering environment. The effect of different rock weathering ranges from rivers dominated by aluminosilicate weathering, mainly of granites, sandstones and shales, to those bearing the signatures of dissolution of carbonates and evaporites and of continental playa deposits. Carbonates are the general predominant lithology undergoing dissolution particularly within the lesser arid areas. The pCO2 in the study rivers is out of equilibrium with respect to atmospheric pCO2, about up to ∼20 times supersaturated relative to the atmosphere but not to such an extent as the Amazon in the floodplain. A roughly positive relationship is observed between solute concentrations and the drought index (DI) for natural waters in the region, indicating a coupled mountain-basin climate has a direct effect. The relative contributions of end-member solute sources to the total dissolved cations from each watershed have been quantitatively estimated using dissolved load balance models, showing the results as evaporite dissolution>carbonate weathering>silicate weathering>atmospheric input for the whole catchment. The areal total dissolved fluxes range from 0.05 to 2.53×106mol/km2/yr, 0.02-2.09×106mol/km2/yr and 0.01-1.04×106mol/km2/yr in the Yili, Zhungarer and Erlqis, respectively, comparable to those of Chinese and Siberia rivers draining sedimentary platforms, even though they are in drastically different climatic regimes. In general, the fluxes from rivers in sedimentary basins are comparable to those from orogenic zones, but are much higher than in the shield regions. The CO2 consumption by aluminosilicate weathering (0.2-284×103mol/km2/yr) is much smaller than in active orogenic belts (19-1750×103mol/km2/yr in similar latitudes and 143-1000×103mol/km2/yr in the tropical basins), but comparable to those of the Chinese (7-106×103mol/km2/yr) and Siberia (16-112×103mol/km2/yr) rivers. © 2013 Elsevier B.V.


Zhu B.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Yu J.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Qin X.,CAS Institute of Geology and Geophysics | Rioual P.,CAS Institute of Geology and Geophysics | And 2 more authors.
Journal of Geographical Sciences | Year: 2014

Based on the palaeoclimatic and palaeoenvironmental evidences of geological history and human history periods, this paper reviews the researches and progresses on the development of the sandy deserts in Xinjiang. It pointed out that the features of tectonic structure in Xinjiang had made both the Tarim Basin and the Junggar Basin being influenced greatly by the foehn effects originated from the planetary wind system of westerly, the East Asian ocean-continental monsoon and the topographical mountain-valley winds. The regional patterns of climate and environment since the Quaternary were characterized by the overall persistent drought accompanied by fluctuations in the secondary scale. Formations of aeolian sediments in the basins and at the margins are a potential response to global climate change, particularly the aridification of the Asian hinterland deduced by the uprising of the Tibetan Plateau and its surrounding highlands. For the question about the formation time of the Taklamakan Desert, because the research methods, objects and information carriers used in previous studies are different, there are many disputes in the academic circles at present. Evidences from aeolian deposits/rocks at the edge and in the hinterland of these sandy deserts and their chronological data indicate that an arid climate and land surface aeolian processes have occurred at the edge of the Tarim Basin and its hinterland areas since the Tertiary period. However, the duration time of these processes at mass scale should have begun after the middle Pleistocene and lasted to the Holocene. Occurrence of dune fields in recent 2000 years in the oasis areas should be greatly influenced by human factors. © 2014 Science Press and Springer-Verlag Berlin Heidelberg.

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