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Reconstructing Centennial-Scale Water Level of Large Pan-Arctic lake. Using Machine Learning Methods

Journal of Earth Science 2023年第4期34卷 1218-1230页

作者： Xinge Liang Chunqiao Song Kai Liu Tan Chen Chenyu Fan Key Laboratory of Watershed Geographic Sciences Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China College of Surveying and Geotechnical Engineering Henan Polytechnic UniversityJiaozuo 454000China University of Chinese Academy of Sciences Beijing 100049China

The pan-Arctic region has the largest number of lake. in the world,which is rather sensitive to changing climate.It is urgently needed to understand how these lake. were changing in the long term.However,there are few lake. with long-term historical monitoring of water level,understanding the hydrologic changes of pan-Arctic lake. over the past century requires the data reconstruction by state-of-art techniques.This study used machine learning algorithms to reconstruct the water level of pan-Arctic lake. on a centennial scale.It further investigated their relationship with long-term hydrological and climatic variables.Comparison of the reconstructed results by four different machine learning models shows that the extreme gradient boosting tree(XGBoost) is better than other three models.Overall,the centennial-scale reconstruction using the XGBoost model performs best for most study lake..Based on the reconstructed results,we can observe that water level changes of several North American lake. are correlated with potential evapotranspiration,followed by precipitation,while the Eurasian lake. are more strongly associated with temperature and wet day frequency.The water level dynamics of pan-Arctic lake. could be largely attributed to Arctic Oscillation and Atlantic Multidecadal Oscillation.This study is expected to advance our understanding of the pan-Arctic lake.water level changes in the past century and to provide a feasible method for reconstructing the regional lake.water level in the long term.

关键词： machine learning water level pan-Arctic lake.

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Distribution and origin of biologically available phosphorus in the water of the Meiliang Bay in summer

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Science China Earth Sciences 2006年第Z1期49卷 146-153页

作者： HUANG Qinghui, WANG Zijian, WANG Donghong, MA Mei & WANG Chunxia State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China Key Laboratory of Yangtze Aquatic Environment (Ministry of Education), College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing China Key Laboratory of Yangtze Aquatic Environment (Ministry of Education) College of Environmental Science and Engineering Tongji University Shanghai China

The investigation and continuous monitoring with an innovative iron oxide embedded cellulose acetate membrane (FeO/CAM) on the concentrations of biologically available phosphorus (BAP) were conducted in the Meiliang Bay of the Taihu lake.during summer in 2004. The results showed that the concentrations of dissolved (FeO-DP), particulate (FeO-PP) and total bioavailable phosphorus (FeO-P) had similar horizontal distribution. The BAP concentrations were the highest in those estuaries in the northern bay. With the decrease of the distance to the estuary or long shore,there was little difference between BAP concentrations in an open lake.area. During the observation period, algal blooms occurred in most waters of the northern bay, which was reflected from the high concentrations of chlorophyll a (Chl-a). While they were not highest in the estuarine waters of those major rivers, this is the case for the BAP concentrations. The concentrations of Chl-a had a significantly positive correlation with those of bioavailable phosphorus in the open area of the Meiliang Bay.With the sediment resuspension induced by wind and wave, BAP concentrations increased in a short-term, indicating that the riverine P inputs mainly contribute to the concentrations of BAP in the estuarine water while internal P release was the major source of BAP in the open lake.area. In the eutrophic shallow lake. the blooms of alga may cause pH increase and further result in internal P release. The above results showed that the new membrane of FeO/CAM can be used to monitor the concentrations of BAP and provide the scientific justifications for the control strategy of the lake.eutrophication.

关键词： phosphorus, bioavailability, eutrophication, resuspension, Taihu lake.

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Characteristics of an early Holocene climate and environment from lake.sediments in Ebinur region, NW China

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Science China Earth Sciences 2005年第2期48卷 258-265页

作者： WU Jinglu SHEN Ji WANG Sumin JIN Zhangdong YANG Xiangdong Nanjing Institute of Geography & Limnology Chinese Academy of SciencesNanjing210008China Nanjing Institute of Geography & LimnologyChinese Academy of SciencesNanjing210008China Nanjing Institute of Geography & LimnologyChinese Academy of SciencesNanjing210008China Nanjing Institute of Geography & LimnologyChinese Academy of SciencesNanjing210008China Nanjing Institute of Geography & LimnologyChinese Academy of SciencesNanjing210008China

The characteristics of climatic environment in the early Holocene epoch were studied through analyzing environmental proxies from the sediments in the Ebinur lake.-a closed one in the arid region. The pollen assemblage and other geochemical indices showed that, the temperature was somewhat low in the period (8.0-11.5 cal kaBP) as a whole, but in the early period (11.5-10.6 cal kaBP) the temperature was higher, in company with more precipitation. In the conversion period from the early Holocene epoch to the middle Holocene epoch (8.9-8.0 cal kaBP) the climate fluctuated remarkably. Particularly the three layers of peat sediment revealed the strong instability of climate in the early Holocene epoch in the Ebinur region. All information on the development of peat and the experimental data of pollen and stable isotopes implied that, the climatic condition at 8.2, 8.6 and 10.5 cal kaBP was characterized by noticeable cold and humidness, and could be regarded as three cold and humid events in the early Holocene epoch.

关键词： early Holocene epoch, climatic evolution, pollen assemblege, stable isotopic record, Ebinur lake.

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Discrimination between extraneous nitrogen input and interior nitrogen release in lake.

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Science China Earth Sciences 2004年第9期47卷 813-821页

作者： XIAO Huayun LIU Congqiang The Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China The Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China

In this study the authors determined the nitrogen isotopes of nitrate and the carbon and nitrogen contents of water samples from the Hongfeng lake.and inflowing streams, and, on this basis, discriminated the extraneous nitrogen input and the interior nitrogen release (organic matter decomposition) in the lake. The results showed that the amount of extraneous nitrogen input into the Hongfeng lake.increases and the interior nitrogen release from the lake.is intensified in winter and spring. Nitrogen mixing is relatively obvious at the catchments between the lake.inlet and inflowing streams, while organic matter decomposition (nitrification) is most intense in the middle and lower reaches of the lake. In winter and spring the organic matter decomposition takes place mainly at the middle level of the water column in the middle and lower reaches of the lake. which has a bearing on the abundance of degraded organic matter at this water level. This part of degraded organic matter contains a considerable proportion of hydrogenous nitrogen in the lake.

关键词： extraneous nitrogen input, interior nitrogen release, Hongfeng lake.

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Origin of Aldehydes in Sediments of Qinghai lake

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Science China Chemistry 1993年第4期36卷 507-512页

作者：应光国范璞 Lanzhou Institute of Geology Academia Sinica Lanzhou 730000 PRC

This paper has analysed the aldehyde fractions in sediments and living organisms of Qinghai lake.using GC-MS and discussed their origin, n-Aldehydes detected in the sediments ranged from C16 to C32 with a maximum at C22 C24 or C26 and showed a strong even over odd predominance. n-Aldehydes in the living organisms analysed ranged from C16 to C32 with a maximum at C26 or C28. The authors believed that aldehydes in modern sediments may directly derive from biosynthesis.

关键词： aldehyde sediment Qinghai lake.

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Geophysical survey on the tectonic and sediment distribution of Qinghai lake.basin

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Science China Earth Sciences 2006年第8期49卷 851-861页

作者： AN Zhisheng1, WANG Ping2, SHEN Ji3, ZHANG Yixiang2, ZHANG Peizhen4, WANG Sumin3, LI Xiaoqiang1, SUN Qianli1, SONG Yougui1, AI Li1, ZHANG Yechun2, JIANG Shaoren2, LIU Xingqi3 & WANG Yong31. Institute of Earth Environment, Chinese Academy of Sciences (CAS), Xi’an 710075, China 2. South China Sea Institute of Oceanology, CAS, Guangzhou 510301, China 3. Nanjing Institute of Geography and Limnology, CAS, Nanjing 210008, China 4. Institute of Geology, China Earthquake Administration, Beijing 100029, China Institute of Earth Environment Chinese Academy of Sciences (CAS) Xi’an China South China Sea Institute of Oceanology CAS Guangzhou China Nanjing Institute of Geography and Limnology CAS Nanjing China Institute of Geology China Earthquake Administration Beijing China

The intensive geophysical survey of Qinghai lake.reveals the buried depth of lake.sediments and their distribution features. The result indicates that there are three important inter- phases of Qinghai lake.sediments: T1 is the rife interphase of the lake. above which sediments are spread all over the lake.basin with roughly the same thickness; T5 is the interphase from which the neotectonic sedimentary cycle begins, and its above sedimentary environment is relatively stable; Tg is the base of the lake.basin. Five west-northwest (WNW) fault belts defined the tectonic structure of Qinghai lake.basin: the central hunch around Haixin Shan with two subbasins both in its north and south. The thickness of the lake.sediments varies at different places, the thickest sediments are found within the two subbasins. According to the depth that the Sparker System can reach, sediment in the northern subbasin is deeper than 560 m, while sediment in the southern subbasin is deeper than 700 m. The correlation between the seismic sequence stratigraph and the lithology of onshore core shows that Qinghai lake.sediments consist of muddy silt, clay silt, silty clay, gravel silty clay, etc.

关键词： sediment, geophysical survey, Qinghai lake.

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Origin of Ketones in Sediments of Qinghai lake

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Science China Chemistry 1993年第2期36卷 237-241页

作者：应光国范璞 Lanzhou Institute of Geology Academia Sinica Lanzhou 730000 PRC

This paper analysed the ketone fractions in sediments and living organisms of Qinghai lake.using GC-MS and discussed their origin,n-Alkan-2-ones detected in the sediments ranged from C12 to C33 with a maximum at n-C25 or n-C29 and showed a strong odd predominance, n-Alkan-2-ones in the living organisms analysed ranged from C15 to C31 with a maximum at n-C27.The authors believed that ketones in modern sediments may directly derive from biosynthesis.

关键词： ketone sediment Qinghai lake.

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Diatom assemblages and quantitative reconstruction for paleosalinity from a sediment core of Chencuo lake.southern Tibet

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Science China Earth Sciences 2004年第6期47卷 522-528页

作者： C. Kamenik R.Schmidt Institute of Limnology Austrian Academy of Sciences A-5310 Mondsee AustriaInstitute of Limnology Austrian Academy of Sciences A-5310 Mondsee Austria

Combining with the diatom-based conductivity transfer function from Qinghai-Xizang (Tibetan) Plateau lake., the lake.salinity for the past 300 years was quantitatively reconstructed based on the analysis of diatom assemblages from a sediment core in Chencuo lake. southern Tibet. The distinct negative relationship between inferred conductivity and re-corded lake.evels in recent years suggests that the lake.salinity can reflect the fluctuations of effective moisture of climate in lake.area. The salinity inferred from diatoms reveals several major hydrological episodes. An obvious desalination of lake.water occurred during the last cold inter-val of the Little Ice Age (about 1845—1885 AD), indicating a cold and moist climate. The lake.salinity presented a rapid increase trend since the middle 1960s, with a peak value and high amplitude of salinity variability in the whole past 300 years. The low effective moisture inferred from the lake.salinity may have contributed to the enhanced evaporation by the continuous in-crease of temperature in recent years.

关键词： diatoms, conductivity or salinity, quantitative reconstruction, Chencuo lake.

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Variation characteristics of heavy metals and nutrients in the core sediments of Taihu lake.and their pollution history

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Science China Earth Sciences 2006年第Z1期49卷 82-91页

作者： LIU Enfeng SHEN Ji LIU Xingqi ZHU Yuxin WANG Sumin Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China

The sedimentary environment change, trophic evolution and heavy metals pollution history of the northern Taihu lake.in the last 100 years are studied according to the sedimentary geochemical proxies of the core sediments, such as grain size, nutrients, heavy metals, diatom, etc. The nutrients in the sediments depended mainly on the lake.internal circulation and the heavy metals were from natural geogenic sources before the 1920s, which were not influenced by human activities generally, and grain size was one of the key factors influencing heavy metals content in the sediments.The alternation of manner and strength of human activities in Taihu lake.catchment before and after the 1920s made the lake.sediments coarser, and hence heavy metals and TP content decreased contrasted with that before the 1920s. TP content in sediments and water increased from the 1950s to late 1970s due to anthropogenic pollutants discharge, and the lake.belonging to mesotrophic state.TN and TOC content and C/N ratio increased due to the increasing external pollutants into Taihu lake.by human activities, TP content also increased obviously in water and sediments, and the diatom association was dominated by eutrophic species since the late 1970s, indicating the eutrophication state of Taihu lake.in this period. Meanwhile the increasing in heavy metals content, such as Cu, Mn,Ni, Pb and Zn, and their proportion of valid fractions in the sediments indicates that they all result from human pollutants since the late 1970s. The heavy metals in the surface sediments have certain potential biological toxicity due to the higher SEM/AVS ratio.

关键词： sediments, heavy metals, nutrients, human activities, pollution history, Taihu lake.

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Soluble salt deposit in the Nihewan beds and its environmental significance

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Science China Earth Sciences 2000年第5期43卷 464-479页

作者：李容全乔建国邱维理翟秋敏李永良 Department of Resources and Environmental Science Beijing Normal University Beijing 100875 China Dean's Office of Shanxi Normal University Linfen 041004 China The Center for Analyses and Tests Beijing Normal University Beijing 100875 China

Observation and experimental analysis of soluble salt deposit along four profiles across the strata deposited in Nihewan paleolake.basin enabled us to recognize the nature and evolution stages of the Nihewan paleolake.and its significance in stratigraphical division and pa-leo-environmental reconstruction. The Nihewan paleolake.was at least a weak-saline to semi-saline lake.and represents an intracontinental lake.in the semi-arid region. The lower member of sedimentary strata in the paleolake.contains gypsum layer and gypsum lamellae. Soluble salt is mainly composed of SO42- and Ca2+ ions, representing a trend of the paleolake.evolvinginto a stage of sulfate lake. The upper member of the strata has predominantly Cl-, K+, and Na+ ions in soluble salt, indicating a starting development of the paleolake.to chlorite lake. but no salt rock was deposited, indicating a drying trend of the area.

关键词： Nihewan beds soluble salt deposit paleo-environment semi-saline lake.

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