Soda lakes and origin of their trona deposits on the Nei Mongol Plateau of China

The Nei Mongol (Inner Mongolia) Plateau is one of the most important salt lake areas in China. Its trona deposits are well known in the world. The soda lakes spread mainly over the northern part of the Ordos Basin, the central part of the Eren Basin, the southeastern part of the Hailar Basin and the Badain Jaran Desert are generally several to several dozen square kilometers, and surrounded by sand dunes. The salinity of soda lake brines is 200–350 g/l, the pH values, 9.09–10.67. The brines mainly consist of Na(K), Cl, SO₄, CO₃, and HCO₃ of the Na(-CO₃-SO₄-Cl) type. Trona deposits in soda lakes on the plateau always occur in “bull’s eye pattern” and are usually in two layers of natron, mirabilite, halite and trona interbedded with black mud containing much illite clay and some gayllussite, dolomite and calcite. Commonly, the soda lakes on the plateau were formed on the depressions from the beginning of early Holocene, but the trona deposits were mainly precipitated under the low temperature in Mid-Holocene (as proved by our freezing experiments and sporo-pollen analysis).     

“Tear drop pattern” potash deposits in lacustrine facies

It is well known that there are two patterns of potash deposition in lacustrine facies: “tear drop pattern” (the Dabsan saline lake is a typical example) and “bull's eye pattern”. Potash-forming in tear drop pattern is still continuing. The 2,678 m A. S. L. lake in the middle of the Qarhan playa in the Qaidam Basin covers an area of 210 km², and has an average depth of 0.39 m. Its MgCl₂ type surface brine is 280–340 g/l in salinity and mainly consists of Na, K, Mg and Cl. As a rule, the potash deposits occur as evaporite distributed in tear drop pattern at the northern and northeastern lakeshore zones. They mostly consist of carnallite and halite, occasionally sylvite. The deposition is very unstable and controlled principally by the varying supply of deposit materials from the Golmud River in the south. The potash deposits were formed when concentration of the surface brine reached a certain degree in the main evaporating season. Their forming process followed some crystalization paths in the phase diagram for the Na, K, Mg/Cl H₂O equilibrium system. Such a sedimentary model of potash deposits in the lacustrine facies is relatively common in nature. Under the extremely arid climate, differential concentration of the nonhomogeneous potassium-rich surface brine produced the potash deposits. Qarhan Salt Lake also had the same pattern of potash depositions and so, in a sense, the Dabsan saline lake is the continuation of the Qarhan salt lake in terms of potash formation. Schmalz (1970) put forward two distributive patterns for evaporite: “tear drop pattern” and “bull's eye pattern”. These patterns exist in both marine and continental salt-bearing basins (including recent salt lakes), and are controlled by the conditions of physical geography, hydrogeology, sedimentology and climatology of each basin. In his works (Sun, 1981; 1984; 1986; 1988) on the origins of potash deposits, the author always referred to them as two models of potash formation. The “tear drop pattern” is one of the salt-forming models and also an important potash-forming model. This paper deals with the formative mechanism of the tear drop pattern potash deposition by presenting the Dabsan saline lake as an example and elucidates on the distributive characteristics and formative processes of potash deposits in the lake.     

The components of the saline lake in Xizang and an approach to their origin

Component data of the saline lakes in Xizang were obtained from field observations in recent years (1976, 1978). Laboratory studies show that there are nearly 37 chemical components in 63 lakes brine and 27 evaporative minerals in nearly 40 saline lakes that reach their depositional stage. Their formative conditions, distributive properties, assemblage properties of some salt minerals, and mechanisms affecting the components of the saline lakes are discussed. A sedimentary model of the early Holocene epoch saline lake is suggested. This work is an aid not only to the understanding of the formation of the saline lakes in the said area, but also to the use of their mineral resources. This paper was published in Chinese inOcean. Limn. Sinica, 1983,14 (4): 342–352.     

VARIATIONS IN ISOTOPIC COMPOSITIONS OF CHLORINE IN EVAPORATION-CONTROLLED SALT LAKE BRINES OF QAIDAM BASIN，CHINA

ＩＮＴＲＯＤＵＣＴＩＯＮＣｈｌｏｒｉｎｅｈａｓｔｗｏｎａｔｕｒａｌｌｙｏｃｃｕｒｉｎｇｓｔａｂｌｅｉｓｏｔｏｐｅｓ,　35Ｃｌａｎｄ　37Ｃｌ.Ｓｅｖｅｒａｌｓｔｕｄｉｅｓｒｅｐｏｒｔｅｄｔｈｅｖａｒｉａｔｉｏｎｓｉｎｔｈｅｉｓｏｔｏｐｉｃｃｏｍｐｏｓｉｔｉｏｎｏｆｃｈｌｏｒｉｎｅｉｎｎａｔｕｒｅ.Ｈｏｗｅｖｅｒ,ｉｎｔｈｅｅａｒｌｙｙｅａｒｓＯｗｅｎａｎｄＳｃｈａｅｆｆｅｒ(1955)ｒｅｐｏｒｔｅｄｎｏｏｂｓｅｒｖａｂｌｅｄｉｆｆｅｒｅｎｃｅｉｎｔｈｅ　37Ｃｌ35Ｃｌｒａｔｉｏｓｉｎｔｅｎｓａｍｐｌｅｓｅｘ…     

Salt lakes and their origins in Xinjiang,China

This paper, based on field data and experimental results, gives an analysis and summary of the types and salt-forming characteristics of salt lakes in Xinjiang, and the distribution and chemical compositions of their brines and groups of salt minerals. The evolution and substance origins of the salt lakes and their salt-forming regularities as seen from analyses of their paleogeographic environment and geological tectonics are also reported. This paper will serve as a reference for further investigation of the Xinjiang salt lakes, and as a guide for fuller utilization of their resources. This paper was published in Chinese inOcean. Limn. Sinica 15(2):168–178, 1984.     

Lake retreat in the Qinghai-Xizang plateau with additional reference to its climatic significance

The author made an approximate dating of the highest shorelines of the three larger interior lakes and proved that during late Q₃ or early Q₄, there existed a higher lake level in the plateau, reflecting that the climate then was much more moist than it is today. It could be presumed from a study of these two ages that such higher lake levels correspond with both the last glacial epoch (i. e., the latter half) and the lowest sea level of the East China Sea then. Moreover, interpretations of aerial photos and an on-the-spot survey revealed that since then these lakes had 8–10 rhythms of retreat, indicating that the climate in central Asia and the plateau at that time had 8–10 comparatively arid periods. As the plateau is still in the faster process of upheaval, it is expected that on a longterm basis, the climate in this region will tend to be continuously dry. However, should there be a neo-glacial epoch in the world, and if the higher lake level really corresponds to the glacial epoch, then in the not distant future, the lake level will possibly rise again to some extent. Thanks are due to the No. 2 Institute of Oceanography of SOA for its analyses of C¹⁴ dating specimens. This paper was published in Chinese inOceanologia et Limnologia Sinica 17(3): 207–216, 1986.     

Effects of temperature,soil moisture,soil type and their interactions on soil carbon mineralization in Zoigê alpine wetland,Qinghai-Tibet Plateau

Wetland stores substantial amount of carbon and may contribute greatly to global climate change debate. However, few researches have focused on the effects of global climate change on carbon mineralization in Zoigê al-pine wetland, Qinghai-Tibet Plateau, which is one of the most important peatlands in China. Through incubation ex-periment, this paper studied the effects of temperature, soil moisture, soil type (marsh soil and peat soil) and their in-teractions on CO2 and CH4 emission rates in Zoigê alpine wetland. Results show that when the temperature rises from 5℃ to 35℃, CO2 emission rates increase by 3.3-3.7 times and 2.4-2.6 times under non-inundation treatment, and by 2.2-2.3 times and 4.1-4.3 times under inundation treatment in marsh soil and peat soil, respectively. Compared with non-inundation treatment, CO2 emission rates decrease by 6%-44%, 20%-60% in marsh soil and peat soil, respec-tively, under inundation treatment. CO2 emission rate is significantly affected by the combined effects of the tempera-ture and soil type (p < 0.001), and soil moisture and soil type (p < 0.001), and CH4 emission rate was significantly af-fected by the interaction of the temperature and soil moisture (p < 0.001). Q10 values for CO2 emission rate are higher at the range of 5℃-25℃ than 25℃-35℃, indicating that carbon mineralization is more sensitive at low temperature in Zoigê alpine wetland.     

Chemical characteristics of four kinds of water in the rongbuk glacier basin, Mount Qomolangma

ＤｕｒｉｎｇｔｈｅｔｈｒｅｅＭｔ．ＱｏｍｏｌａｎｇｍａＥｘｐｅｄｉｔｉｏｎｓｏｆ１９５９－１９６０,１９６６－１９６８ａｎｄ１９７５,ＣｈｉｎｅｓｅｓｃｉｅｎｔｉｓｔｓｈａｄｏｂｔａｉｎｅｄｍａｎｙｄａｔａｏｆｇｌａｃｉｅｒｓｉｎｔｈｅｄｉｓｔｒｉｃｔｏｆＭｔ．Ｑｏｍｏｌａｎｇｍａ（Ｗａｎｇｅｔａｌ．,１９８０;Ｘｉｅｅｔａｌ．,１９７５;Ｚｈａｎｇｅｔａｌ．,１９７５）．ＩｎＭａｙ１９９７,Ｐｒｏｆ．ＱｉｎＤａｈｅａｎｄＰｒｏｆ．ＰａｕｌＡ．Ｍａｙｅｗｓｋｉｏｒｇａｎｉｚｅｄａｎｏｔｈｅ…     

Phytoplankton Community Dynamics in West Lake After Drawing Water from the Qiantang River

1INTRODUCTIONTheWestLake ( 30°1 5′N ,1 2 0°1 6′E)isasmallshallowlakeinthewesternpartofHangzhouCityinthesoutheasterncoastalareaofChina.Thelakeissur roundedonthreesidesbyhills ;andisfamousforitspicturesquesceneryandinterfusionofhillsandwaterbodies.Thesurfaceareaisabout 5 .66km2 andmeandepthis 1 .8m .Beforethe 1 95 0s ,thelakewaterwascleanandmacrophytesgrewveryluxuriantlyinthelit toralareasofthelake .In 1 95 2 ,WestLakewasdredgedand 70 0× 1 0 4m3 mudwasremovedfromthebottomofthelake …     

Progress of limnology in China

The following six aspects in the utilization of lake resources and progress of limnological research in China are described: 1. Expeditions for comprehensive investigation of lakes; 2. Physical limnology; 3. lacustrine sedimentology and paleolimnology; 4. Hydrobiology and ecology; 5. Hydrochemistry and environmental protection; 6. Development and utilization of lake resources. This paper was published in Chinese inScientia Limnologica Sinica 1 (1): 1–11, 1989.     

RELATIONSHIP BETWEEN QINGHAI LAKE LEVEL DESCENDING AND ARTIFICIAL WATER－CONSUMPTION

ＲＥＬＡＴＩＯＮＳＨＩＰＢＥＴＷＥＥＮＱＩＮＧＨＡＩＬＡＫＥＬＥＶＥＬＤＥＳＣＥＮＤＩＮＧＡＮＤＡＲＴＩＦＩＣＩＡＬＷＡＴＥＲ－ＣＯＮＳＵＭＰＴＩＯＮ￥ＰｅｎｇＭｉｎ（彭敏）ＣｈｅｎＧｕｉｃｈｅｎ（陈桂琛）ＺｈｏｕＬｉｈｕａ（周立华）（Ｎｏｒｔｈｗｅ...     

Abundance and production ofBranchiura sowerbyi (Oligochaeta: Tubificidae) in two typical shallow lakes (Hubei, China)

An April 1996 to March 1997 comparative study on the abundance and secondary production ofBranchiura sowerbyi Beddard, 1892 in two typical shallow lakes showed that in Houhu, an algae-dominated lake, the worm density (68 ind·m⁻²) peaked in July, biomass (1.930 g·m⁻²) peaked in June, while in Biandantang, a macrophyte-dominated lake, standing stock (density: 60 ind·m⁻²; biomass: 1.019 g·m⁻² in wet weight) peaked in December. Secondary production of the animal in Houhu Lake was 3.413 g wet wt m⁻² a⁻¹, a little more than that (2.675 g wet wt m⁻² a⁻¹) in Biandantang Lake. Their turnover rates (P/B ratios) were 4.0 and 5.0, respectively. Project (39600019 and 39430101) supported by NSFC.     

Preliminary studies on the role of protozoa in the food web of Donghu Lake

ＩＮＴＲＯＤＵＣＴＩＯＮＪｏｈａｎｎｅｓ (1 965)ｆｉｒｓｔｓｈｏｗｅｄｔｈｅｉｍｐｏｒｔａｎｃｅｏｆｐｒｏｔｏｚｏａａｓｒｅｍｉｎｅｒａｌｉｚｅｒｓｉｎｍａｒｉｎｅｅｎｖｉｒｏｎｍｅｎｔｓ.Ｔｈｅｓｉｇｎｉｆｉｃａｎｃｅｏｆｐｒｏｔｏｚｏａｉｎｔｈｅｆｒｅｓｈｗａｔｅｒｆｏｏｄｗｅｂｈａｓｂｅｅｎｋｎｏｗｎｆｏｒｔｈｅｐａｓｔ2 0ｙｅａｒｓ.Ｐｒｏｔｏｚｏａｉｓａｍａｉｎｐｒｅｄａｔｏｒｏｆｐｌａｎｋｔｏｎｉｃｂａｃｔｅｒｉａａｎｄｐｈｙｔｏｐｌａｎｋｔｏｎ ,ａｎｄａｌｓｏａｆｏｏｄｓｏｕｒｃｅｏ…     

察尔汗盐湖卤水结盐条件分析与防治结盐的措施

本文通过对近年来在盐湖开采和试验过程中采卤设备以及输卤管、渠结盐实例的分析,得出如下结论:控制卤水结盐的主要因素是卤水的水化学类型以及矿化度、Na~+/Mg~(++)、Na~+/SO_4~=系数和CaCl_2的含量,其中Na~+/Mg~(++)系数是控制各类型卤水结盐的关键。并提出用回灌老卤的措施来解决卤水结盐问题。     

Wetlands in China: Feature, value and protection

The estimated total area of wetland in China is more than 25.9 million hectares including about 11.9 million hectares of marshes and bogs, 9.1 million hectares of lake and about 2.2 million hectares of coastal salt marshes and mudflats. The area of wetland is equivalent to 2.7% of the land surface. China also has 2.7 million hectares of shallow sea water (less 5m in depth at low tide). Marshes and bogs are equivalent 1.3% of the land surface. Only three provinces (regions)—Qinghai, Xizang (Tibet) and Heilongjiang — have a larger total area of marsh and bog. According to the structure, type and development of wetland in different river basins, wetland can be classified nine main regions. The experiments indicate that the coefficient of the marsh to regulate flood is similar to that of lakes. Wetlands occupy 17.8% of the Sanjiang Plain area, the annual carbon contribution is 0.78 × 10⁴t. Carbon released from marsh soil return into atmosphere is 3.95 × 10⁶t/a. At present there is a sharp contradiction between population growth and natural resources shortage, causing wetland to be exerted with huge pressures and serious threats. Foundation item: Under the auspices of the Key B Item of the Chinese Academy of Sciences (KZ951-B1-201-02). Biography: LU Xian-guo (1957 —), male, a native of Changchun City, Jilin Provice, professor. His research interests include wetland process and environmental effect.     

Distributions of sulfur pollutants in East Asia

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｖｅｒｙｉｍｐｏｒｔａｎｔｔｏｒｅａｌｉｚｅｔｈｅｄｉｓｔｒｉｂｕｔｉｏｎｓｏｆｐｏｌｌｕｔａｎｔｓｂｅｆｏｒｅｔｈｅｐｏｌｌｕｔｉｏｎｃａｎｂｅｃｏｎｔｒｏｌｌｅｄｓｕｃ ｃｅｓｓｆｕｌｌｙ .Ｏｗｉｎｇｔｏｔｈｅｌａｃｋｏｆｓｙｓｔｅｍａｔｉｃａｌｏｂｓｅｒｖａ ｔｉｏｎｓｉｎａｂｒｏａｄａｒｅａ ,ｎｕｍｅｒｉｃａｌｓｉｍｕｌａｔｉｏｎｈａｓｂｅ ｃｏｍｅａｐｏｗｅｒｆｕｌｔｏｏｌｔｏｕｎｄｅｒｓｔａｎｄｔｈｅｄｉｓｔｒｉｂｕｔｉｏｎｓｏｆｐｏｌｌｕｔａｎｔｓａ…     

ORGANIC GEOCHEMISTRY MARKERSOF CLIMATIC EVOLUTION IN LOESSREGION OF CHINA

Two hundred and thirty-five samples collected from Weinan loess section (L₂ – S₀) have been analyzed by TOC (total organic carbon) and pyrolysis hydrocarbons. The curve of TOC with depth has been set up and compared well with other climatic markers. The main periods of TOC variation of the last 0.14 Ma are 67.08 ka and 18.29 ka, which is near with the periods of the variation of sunshine, showing that the TOC variation may be controlled by the variation of 65°N sun-shine. The distribution of pyrolysis hydrocarbon and its parameters shows that there are two kinds of hydrocarbon associated with climatic change. One is called hydrocarbon pyrolysted directly from organism (pHC_2–1) which is in the range of T _max350°C – 500°C, and associated with atmospheric water. The other is called carbonate inclusion hydrocarbon (pHC_2–2) which is in the range of T _max 500°C – 600°C and formed by evaporation and associated with dry climate. The formula calculating humidity has been deduced Og=pHC_2–1/(pHC_2–1 + pHC_2–2). The range of humidity of the section is 47% – 77% and the reducing order is S_1–3, S_1–2, S₀, S_1–1, S_1–4, S_1–1, L_1–1, L_1–3, and L_1–5. And the trend of the humidity is still increasing today.     

Nutrients in seawater and interstitial water of the sediments in the Huanghe River estuarine area (November)

The investigation shows that the concentrations of nutrients are high in estuarine and coastal waters and low in offshore waters. The concentration of nitrate in estuaries is controlled through a physical mixing process and is also affected by biotic activity. The annual transport of total inorganic nitrogen and dissolved phosphate-phosphorus from the Huanghe River water to the sea is about 8.45 ×10⁴ and 1.45×10³ tons respectively. The distributions of inorganic nitrogen and silicate in interstitial water of surface sediments are similar to those in surface and bottom seawater. Their contents in interstitial water are 227–552 μmol/l (average375) for ammonia, 0.31–9.0 μmol/l (average 1.6) for nitrite, 0–41 μmol/l (average6.0) for nitrate, and 41–139 μmol/l (average 77) for silicate. The average concentrations of phosphate in the surveyed area are 0.64 μmol/l for seawater and 1.2 μmol/l for interstitial water. A cycle of phosphate in the estuary is also suggested in this paper. Contribution No. 1434 from Institute of Oceanology, Academia Sinica.     

EVOLUTIONARY CHARACTERISTICS OF LAKES AND PALAEOCLIMATIC UNDULATION IN THE Q AID AM BASIN,CHINA

The Qaidam Basin is. a tectonically controlled depression at 2700 m altitude on the northern margin of the Tibet Plateau. A succession of Neogene clastic sediments indicates lake depocentre migration from NW to SE. Towards late Pliocene, evaporative conditions developed with formation of gypsum, halite, celestite, mirabilite and bloedite. Continued deformation through Pleistocene developed a series of NW- SE trending domes and troughs. This setting continued to exert a controlling influence on basin and brine evolution and the progressive development of sulfate to chloride brines as, dry conditions intensified in late Pleistocene, at the end of which, extensive flat floors were formed in Dalangtan, Qarhan and other playas.The, model, which was set up based on the synthetic analyses, divides the fluctuating palaeoclimate since 750ka,B. P. into 11 warm and humid stages and 10 dry and cold stages. The water of the lakes evaporated during the dry-cold periods and were freshened during the warm-humid periods