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Nutrient fluxes induced by disturbance in Meiliang Bay of Lake Taihu

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Science china Earth sciences 2006年第z1期49卷 186-192页

作者： LUO Liancong, QIN Boqiang, ZHU Guangwei, SUN Xiaojing, HONG Dalin, GAO Yajun & XIE Rui nanjing institute of {2. & Limnology, chinese academy of sciences, nanjing 2.0008, china nanjing Hydraulic Research institute, Ministry of Water Resources, nanjing 2.002., china 1. nanjing institute of {2. & Limnology Chinese Academy of Sciences Nanjing 210008 China2. Nanjing Hydraulic Research Institute Ministry of Water Resources Nanjing 210024 China

A wave flume experiment was conducted to study nutrient fluxes at water-sediment interface of Meiliang Bay under different hydrodynamic conditions. The results reveal that hydrodynamics has remarkable effects on nutrient fluxes in this area. With a bottom wave stress of 0.019 N m-2.(equivalent to disturbance caused by wind SE 5-7 m s-1 at the sediment sample site of Meiliang Bay), the fluxes of TN, TDN and NH4+-N were separately 1.92. 10-3, -1.81 × 10-4 and 5.2.× 10-4 mg m-2.s-1(positive for upward and negative for downward), but for TP, TDP and SRP, the fluxes were 5.69 × 10-4, 1.68 × 10-4 and -1.2. × 10-4 mgm-2.s-1. In order to calculate the released amount of nutrients based on these results, statistic analysis on the long-term meteorological data was *** result shows that the maximum lasting time for wind SE 5-7 m s-1 in this area is about 15 h in summer. Further calculation shows that 111 t TN, 32.t NH4+-N, 34 t TP and 10 t TDP can be released into water (the sediment area was 47.45% of the whole surface area), resulting in concentration increase of 0.02., 0.007, 0.007 and 0.002.mg L-1 separately. With stronger disturbance (bottom wave stress is 0.2.7 N m-2.which is equivalent to disturbance caused by wind SE 10-11 m s-1 at the same site), there has been significant increase of nutrient fluxes (1.16× 10-2. 6.76×10-3, 1.14× 10-2.and 2.14× 10-3 mgm-2.s-1 for TN, DTN and NH4+-N and TP). The exceptions were TDP with flux having a decrease (measured to be 9.54× 10-5 mgm-2.s-1 ) and SRP with flux having a small increase (measured to be 5.42.× 10-5 mgm-2.s-1). The same statistic analysis on meteorological data reveal that the maximum lasting time for wind SE 10-11 m s-1 is no more than 5 h. Based on the nutrient fluxes and the wind lasting-time, similar calculations were also made suggesting that 2.2.t TN, 134.9 t TDN, 2.8 t NH4+-N, 42.7 t TP, 2.0 t TDP and 1.1 t SRP will be released from sediment at this hydrodynamic condition resulting in the concentration

关键词： hydrodynamics disturbance water-sediment interface nutrient release flux Lake Talhu.

Background contents of heavy metals in sediments of the Yangtze River system and their calculation methods

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Journal of Environmental sciences 1995年第4期7卷 422-429页

作者： Zhang Chaosheng, Zhang Shen, Zhang Licheng, Wang Lijun(institute of geography ,{2. , Beijing 100101 , china) Inst of geography Chinese Academy of Sci Beijing China China

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关键词： Yangtze River sediments heavy metalsi robust statistics data transformation.

Economic development and major guarantee projects in the region along the Yangtze River

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Journal of Geographical sciences 1998年第3期8卷 83-92页

作者： CHEN Wen YU Xiaogan nanjing institute of {2. & Limnology, chinese academy of sciences nanjing 2.0008 china

The region along the Yangtze River is the major exploitation belt and a linkage of eastern and western parts of china. It plays an essential role in the national economic development. Since the implementation of the reform and open door policy, regional economy has got rapidly developed. In the process of development, the region also faces difficulties like energy shortage, backward transportation facilities, grain output reduction, and environmental deterioration. Countermeasures are put forward in the paper to cope with the difficulties.

关键词： regional economy development strategy industry transportation energy Yangtze Valley.

THE CHARACTERISTICS AND MAIN PROBLEMSOF MINORITY REGIONS IN china

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chinese Geographical Science 2001年第4期11卷 8-13页

作者： ZHANG Luo-cheng, WU Chu-cai(nanjing institute of {2. & Limnology, the chinese academy of sciences, nanjing 2.0008, P. R. china) nanjing institute of {2. & Limnology the Chinese Academy of Sciences Nanjing P. R. China

ABSTRACT: china is a country that has a large number of minorities, who live in specific regions which are mainly located in central and west china. These regions are abundant in natural resources, which are potential advantages and also an important basis for economic development in these regions. They are of general importance for china in strategic and ecological terms. They will not only affect the environment for survival of the minority regions but also affect the sustainable development of the eastern and central parts of china and even the survival and development of the chinese nation as a whole. Minorities live in relatively compact communities, among the 55 minorities, 35 of them were highly compact minorities, with a compact level of more than 90% . Here the development in infrastructure as well as social and economic development (e. g. export-oriented economy) has been and is still slow, regional poverty are most concentrated. The economic structures in minority areas are still in the low stage, which have resulted in underdevelopment in these regions.

关键词： minority regions development problems

Daily variation of carbon flux in soils of Populus euphratica forests in the middle and lower reaches of the Tarim River

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Progress in Natural Science:Materials International 2007年第5期17卷 584-590页

作者： Huang Xiang , Chen Yaning , Li Weihong , Ma Jianxin and Chen Yapeng (Xinjiang institute of Ecology and geography,{2., Urumqi 830011, china Graduate University,{2., Beijing 100039, china) [a]Xinjiang institute of Ecology and geography Chinese Academy of Sciences Urumqi China [b]chinese academy of {2. Graduate University Beijing China

In order to lucubrate the daily variation of respiration in soils of Populus euphratica forests and analyze its relationship with environmental factors in the middle and lower reaches of the Tarim River, the LI-8100 instrument of soil CO2.flux system was used to measure the parameters of soil carbon flux and air temperature 10 cm above ground surface along the profiles of Usyman, Archy River, Yengisu and Karday, and the relationships between the soil carbon flux and the soil moisture content were analyzed. The nonlinear regression analysis was carried out with the software SPSS13.0. We observed that: (1) soil respiration began to be restrained when the air temperature was up to 30℃10 cm above the ground surface; (2. the rates of soil respiration under the forests of Populus euphratica were significantly different at various moisture contents, the soil carbon flux was high along the Usyman profile, which has a high soil moisture content, and it was low along the profiles of Archy River, Yengisu and Karday, which has a low soil moisture content; (3) the exponential model can be used to explain the relationship between soil respiration and air temperature 10 cm above the ground surface. The average Q10 values along the profiles of Usyman, Archy River, Yengisu and Karday are 0. 61, 0.16, 0. 2. and 0. 35 respectively, much lower than the average of the world; (4) there is a positive correlation between the soil carbon flux and the soil moisture content.

关键词： Populus euphratica soil carbon flux air temperature 10 cm above ground surface soil moisture content the Tarim River.

The reconstruction and interpretations of lake status at 6 ka and 18 ka *** inland mainland Asia

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chinese Science Bulletin 1998年第14期43卷 1145-1157页

作者： QIN Boqiang 1, SHI Yafeng 1 and YU Ge 2. 3 1. nanjing institute of {2. & Limnology, chinese academy of sciences, nanjing 2.0008, china 2. Dynamic Palaeoclimatology, Lund University, PO Box 117, S 2.1 00, Lund, Sweden 3. Department of nanjing institute of {2. & Limnolagy Chinese Academy of Sciences Nanjing China Dynamic Palaeoclimatology Lund University Lund Sweden Department of Geology and Ocean sciences Nanjing University Nanjing China

By means of survey of literature through compilations of sedimentological, biogeological and geomorphologic data, the inland lake level changes in arid or semi arid mainland Asia at 6 and 18 ka B.P. have been reconstructed. The results showed that the lakes from western and northwestern Asia were characterized by very high water levels at 18 ka B.P., but low or intermediate water stands at 6 ka B.P. The high lake level in this region was associated with the southward displacement of westerlies, therefore, the extent of the high lake stand indicated the southern flank of westerlies during the glaciation. Conversely, the lakes from the eastern and southern Asia registered comparative low levels at 18 ka B.P. and significantly high one at 6 ka B.P. The lowering of lake level at 18 ka B.P. was caused by the weakened summer monsoon and the high lake level at 6 ka B.P. by the enhanced summer monsoon induced by the enlarged thermal contrast between land and ocean. The extent of high lake levels indicated the northern boundary of monsoon expansion. Between the above two regions, there is a climatic transitional zone in the Central Asia where the lake behavior was close to that in southeastern Asia at 6 ka B.P. but became similar to that in northwestern Asia at 18 ka B.P. Thus this zone became a transitional sector from the monsoon to the westerlies.

关键词： lake status inland mainland Asia westerlies monsoon.

Seasonal variation of potential denitrification rates of surface sediment from Meiliang Bay, Taihu Lake, china

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Journal of Environmental sciences 2010年第7期22卷 961-967页

作者： Jicheng Zhong, Chengxin Fan, Guofeng Liu, Lei Zhang, Jingge Shang, Xiaozhi GuState Key Laboratory of Lake Science and Environment, nanjing institute of {2. and Limnology, chinese academy of sciences, nanjing 2.0008, china. [a] State Key Laboratory of Lake Science Environment Nanjing Institute of Geography Limnology Chinese Academy of Sciences Nanjing 210008 China

The regulatory effects of environmental factors on denitrification were studied in the sediments of Meiliang Bay, Talhu Lake, in a monthly sampling campaign over a one-year period. Denitrification rates were measured in slurries of field samples and enrichment experiments using the acetylene inhibition technique. Sediment denitrification rates in inner bay and outer bay ranged from 2.8 to 51.5 nmol N2.（g dw （dry weight）·hr） and from 1.5 to 81.1 nmol N2.（g dw·hr）, respectively. Sediment denitrification rates were greatest in the spring and lowest in the summer and early autumn, due primarily to seasonal differences in nitrate concentration and water temperature. For each site, positive and linear relationships were regularly observed between denitrification rate and water column nitrate concentration. Of various environmental factors on denitrification that we assessed, nitrate was determined to be the key factor limiting denitrification rates in the sediments of Meiliang Bay. In addition, at the two sites denitrification rates were also regulated by temperature. The addition of organic substrates had no significant effect on denitrification rate, indicating that sediment denitrification was not limited by organic carbon availability in the sediments. Nitrate in the water column was depleted during summer and early autumn, and this suppressed effective removal of nitrogen from Taihu Lake by denitrification.

关键词： denitrification sediment environmental factors Taihu Lake

SEDIMENT HAZARDS IN THE LOWER YELLOW RIVER

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International Journal of Sediment Research 1999年第2期14卷 25-30页

作者： SHI Changxing (Supported by the National Natural Science Foundation of china) (institute of {2., chinese academy of sciences, china)

The main sediment hazards in the lower Yellow River are flooding, channel erosion, desertification of cultivated lands, waterlogging. and soil salinization. Some of the hazards are the direct results of sediment movement and the others are related with sediment movement by the special landforms which themselves are the results of sediment movement. On the one hand, the sediment hazards,such as flooding. bank erosion and soil salinization, are aggravated by serious sediment accumulation in the Yellow River channel and irrigation canals due to heavy sediment load of the rived On the other hand, the distribution of the sediment deposit of different grain sizes is also a main factor influencing flooding, desertification, waterlogging and soil salinization hazards. The paper suggests to change the distribution of sedimentation as a measure of mitigating sediment hazards.

关键词： Sediment hazard The lower Yellow Rived Mitigation of sediment hazard

Geomorphologic evidence of phased uplift of the northeastern Qinghai-Tibet Plateau since 14 million years ago

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Science china Earth sciences 2004年第9期47卷 822-833页

作者： LU Huayu1, WANG Xiaoyong1, AN Zhisheng1, MIAO Xiaodong1, ZHU Rixiang3, MA Haizhou2. LI Zhen4, TAN Hongbing2.& WANG Xianyan1 1. State Key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, chinese academy of sciences, Xi’an 710075{2. 2. Qinghai institute of Salt Lakes, chinese academy of sciences. Xining 810008,{2. 3. institute of Geology and Geophysics, chinese academy of sciences, Beijing 10002.,{2. 4. Department of geography, Qinghai Normal University, Xining 810008,{2. chinese Acad Sci Inst Earth Environm State Key Lab Loess & Quaternary Geol Xian 710075 Peoples R China chinese Acad Sci Qinghai Inst Salt Lakes Xining 810008 Peoples R China chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China Qinghai Normal Univ Dept Geog Xining 810008 Peoples R China

A typical sequence of fluvial terraces and aeolian deposits overlying these ter- races were multidisciplinary investigated. New evidences for uplift process of the northeastern Qinghai-Tibetan Plateau in the past 14 million years were obtained. At least 11 river terraces along Huangshui, the first-class tributary of Yellow River, at the Xining-Huzhu region are identi- fied. While the first one (T1) is classified as an accumulation terrace, the others are all basement river terraces, which consist of the Tertiary sandstone and siltstone bedrock, fluvial gravel and pebbles and the overlying aeolian loess-Red Clay deposit. Samples from the aeolian deposits were examined for paleomagnetic stratigraphic reconstruction (1030 samples), luminescence dating (16 samples), magnetic susceptibility and grain-size distribution (more than 4000 sam- ples). The luminescence dating and stratigraphic correlation suggest that terraces of Tll, T10, T8, T7, T3, T2. T1 were formed at 14, 11.3, 1.55, 1.2. 0.15, 0.07 and 0.01 million years ago, re- spectively. Sedimentological analysis and geomorphological observation indicate that formation and evolution of these terraces were mainly driven by tectonic uplift. Therefore, the terrace se- quence provides an ideal geological record, of the uplift process of the northeastern during the past 14 million years, and the timings of the terraces formation are regarded as the timings of tectonic uplift. The significant uplifting events took place at 14, 11.3, 1.2.and 0.15 mil- lion years ago, respectively. The fluvial incision at the Xining-Huzhu region is less than 100 m during a period of ~12.million years in the Miocene era (between the Tll and T9), while the Huangshui River had incised 432.m during the past 1.2.million years (from T7 to the present floodplain). The river incision process clearly demonstrates that accelerated rising of the north- eastern Qinghai-Tibet Plateau during the late Cenozoic, and provides new evidence of previous thoughts

关键词： river terrace, tectonic uplift, loess-Red Clay, the past 14 million years, northeastern Qinghai-Tibet Plateau.