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Sample records for lake region china

  1. Establishing eutrophication assessment standards for four lake regions, China.

    PubMed

    Huo, Shouliang; Ma, Chunzi; Xi, Beidou; Su, Jing; Zan, Fengyu; Ji, Danfeng; He, Zhuoshi

    2013-10-01

    The trophic status assessment of lakes in different lake regions may provide important and fundamental information for lake trophic state classification and eutrophication control. In this study, a region-specific lake eutrophication assessment standard was established through a frequency distribution method based on chlorophyll-a concentration. The assessment standards under the oligotrophic state for lakes in the Eastern plain, Yungui Plateau, Northeast Plain and Mountain Mongolia-Xinjiang regions are total phosphorus of 0.068, 0.005, 0.011, 0.005 mg/L; total nitrogen of 1.00, 0.16, 0.37, 0.60 mg/L; Secchi depth of 0.60, 8.00, 1.55, 3.00 m; and COD(Mn) of 2.24, 1.00, 5.11, 4.00 mg/L, respectively. Moreover, a region-specific comprehensive trophic level index was developed to provide an understandable assessment method for the public. The results indicated that the frequency distribution analysis based on chlorophyll-a combined with trophic level index provided a useful metric for the assessment of the lake trophic status. In addition, the difference of eutrophication assessment standards in different lake regions was analyzed, which suggested that the sensitivities of algae to nutrients and the assessment standard of trophic status possessed significant regional differences for the four lake ecoregions. Lake eutrophication assessment standards would contribute to maximizing the effectiveness of future management strategies, to control and minimize lake eutrophication problems.

  2. Surveillance of Schistosoma japonicum Infection in Domestic Ruminants in the Dongting Lake Region, Hunan Province, China

    PubMed Central

    Liu, Jinming; Zhu, Chunxia; Shi, Yaojun; Li, Hao; Wang, Lanpin; Qin, Shangtian; Kang, Saie; Huang, Yanpin; Jin, Yamei; Lin, Jiaojiao

    2012-01-01

    Background Schistosomiasis japonica is prevalent in Asian countries and it remains a major public health problem in China. The major endemic foci are the marsh and lake regions of southern China, particularly the Dongting Lake region bordering Hunan and Hubei provinces, and the Poyang Lake region in Jiangxi province. Domestic ruminants, especially bovines, have long been considered to play a major role in the transmission of Schistosoma japonicum to humans. Methods and Findings A miracidial hatching technique was used to investigate the prevalence of S. japonicum infections in domestic ruminants and field feces collected from two towns located to the south and east of Dongting Lake, Hunan province, between 2005 and 2010. The overall prevalence of infection was not significantly reduced from 4.93% in 2005 to 3.64% in 2008, after which it was maintained at this level. Bovines comprised 23.5–58.2% of the total infected ruminants, while goats comprised 41.8–76.5%. Infection rates in cattle and goats were significantly higher than those found in buffalo in most study years. The prevalence in buffalo younger than three years was significantly higher than that in those aged over three years. All the positive field samples of feces were derived from bovines in Nandashan. In Matang Town, 61.22% of the positive field feces were from bovines, while the rest were from goats. The positive rates for field feces were approximately the same in April and November/October. Conclusions The present study found that bovines and goats are major sources of S. japonicum infection in the Dongting lake region and there was age-related resistance in buffalo. Both bovines and goats should be treated equally when controlling S. japonicum infections in the Dongting lake region. It is essential to conduct an additional mass treatment in late March or early April, in addition to the original treatment scheme. PMID:22359638

  3. Identifying Watershed Regions Sensitive to Soil Erosion and Contributing to Lake Eutrophication--A Case Study in the Taihu Lake Basin (China).

    PubMed

    Lin, Chen; Ma, Ronghua; He, Bin

    2015-12-24

    Taihu Lake in China is suffering from severe eutrophication partly due to non-point pollution from the watershed. There is an increasing need to identify the regions within the watershed that most contribute to lake water degradation. The selection of appropriate temporal scales and lake indicators is important to identify sensitive watershed regions. This study selected three eutrophic lake areas, including Meiliang Bay (ML), Zhushan Bay (ZS), and the Western Coastal region (WC), as well as multiple buffer zones next to the lake boundary as the study sites. Soil erosion intensity was designated as a watershed indicator, and the lake algae area was designated as a lake quality indicator. The sensitive watershed region was identified based on the relationship between these two indicators among different lake divisions for a temporal sequence from 2000 to 2012. The results show that the relationship between soil erosion modulus and lake quality varied among different lake areas. Soil erosion from the two bay areas was more closely correlated with water quality than soil erosion from the WC region. This was most apparent at distances of 5 km to 10 km from the lake, where the r² was as high as 0.764. Results indicate that soil erosion could be used as an indicator for identifying key watershed protection areas. Different lake areas need to be considered separately due to differences in geographical features, land use, and the corresponding effects on lake water quality.

  4. Identifying Watershed Regions Sensitive to Soil Erosion and Contributing to Lake Eutrophication—A Case Study in the Taihu Lake Basin (China)

    PubMed Central

    Lin, Chen; Ma, Ronghua; He, Bin

    2015-01-01

    Taihu Lake in China is suffering from severe eutrophication partly due to non-point pollution from the watershed. There is an increasing need to identify the regions within the watershed that most contribute to lake water degradation. The selection of appropriate temporal scales and lake indicators is important to identify sensitive watershed regions. This study selected three eutrophic lake areas, including Meiliang Bay (ML), Zhushan Bay (ZS), and the Western Coastal region (WC), as well as multiple buffer zones next to the lake boundary as the study sites. Soil erosion intensity was designated as a watershed indicator, and the lake algae area was designated as a lake quality indicator. The sensitive watershed region was identified based on the relationship between these two indicators among different lake divisions for a temporal sequence from 2000 to 2012. The results show that the relationship between soil erosion modulus and lake quality varied among different lake areas. Soil erosion from the two bay areas was more closely correlated with water quality than soil erosion from the WC region. This was most apparent at distances of 5 km to 10 km from the lake, where the r2 was as high as 0.764. Results indicate that soil erosion could be used as an indicator for identifying key watershed protection areas. Different lake areas need to be considered separately due to differences in geographical features, land use, and the corresponding effects on lake water quality. PMID:26712772

  5. Carbon dioxide and methane supersaturation in lakes of semi-humid/semi-arid region, Northeastern China

    NASA Astrophysics Data System (ADS)

    Wen, Zhidan; Song, Kaishan; Zhao, Ying; Jin, Xiuliang

    2016-08-01

    Understanding concentrations of carbon dioxide (CO2) and methane (CH4) in lakes is an important part of a comprehensive global carbon budget. We estimated data on the partial pressure of CO2 (pCO2) and CH4 (pCH4) from sampling with 95 lakes in semi-humid/semi-arid region of Northeastern China during ice-free period. Both pCO2 and pCH4 varied greatly among the study sites. p(CO2) values in these lakes ranged from 21.9 to 30,152.3 μatm (n = 403), and 91% of lakes in this survey were supersaturated with CO2. p(CH4) values ranged from 12.6 to 139,630.7 μatm with all sites in this study of CH4 sources to the atmosphere during the ice-free period. The collected urban lakes samples exhibited higher pCO2 and pCH4 than wild lakes samples. Either the mean value of p(CO2) or p(CH4) in saline waters is higher than in fresh waters. Correlation analysis implied that the partial pressure of the GHGs (CO2 and CH4) showed statistically correlations with water environment indicators like pH, dissolved organic carbon (DOC), total nitrogen (TN), total phosphorus (TP), and chlorophyll a (Chla). However, the most of the relationships showed a high degree of scatter, only pH might be used as the predictor of the gas partial pressure based on the result of this study (rpCO2 = -0.437, p < 0.01, n = 382; rpCH4 = -0.265, p < 0.01, n = 400). Furthermore, salinity could be a good predictor for p(CO2) and p(CH4) in 83 freshwater lakes in our study (rpCO2 = 0.365, rpCH4 = 0.323, p < 0.01, n = 348). The mean CO2 flux increased with the decreasing lake area size. The calculated annual areal carbon emission rate is 560.2 g C m-2 from 95 lakes in Northeastern China. We could not extrapolate carbon emission from these lakes to the boreal region or a wider scale because of the change of environmental conditions.

  6. Spatial distribution and source apportionment of PFASs in surface sediments from five lake regions, China

    PubMed Central

    Qi, Yanjie; Huo, Shouliang; Xi, Beidou; Hu, Shibin; Zhang, Jingtian; He, Zhuoshi

    2016-01-01

    Perfluoroalkyl substances (PFASs) have been found in environment globally. However, studies on PFAS occurrence in sediments of lakes or reservoirs remain relatively scarce. In this study, two hundred and sixty-two surface sediment samples were collected from forty-eight lakes and two reservoirs all over China. Average PFAS concentrations in surface sediments from each lake or reservoir varied from 0.086 ng/g dw to 5.79 ng/g dw with an average of 1.15 ng/g dw. Among five lake regions, average PFAS concentrations for the lakes from Eastern Plain Region were the highest. Perfluorooctanoic acid, perfluoroundecanoic acid and perfluorooctane sulfonic acid (PFOS) were the predominant PFASs in surface sediments. The significant positive correlations between PFAS concentrations and total organic carbon, total nitrogen and total phosphorus contents in sediments revealed the influences of sedimentary characteristics on PFAS occurrence. A two-dimensional hierarchical cluster analysis heat map was depicted to analyze the possible origins of sediments and individual PFAS. The food-packaging, textile, electroplating, firefighting and semiconductor industry emission sources and the precious metals and coating industry emission sources were identified as the main sources by two receptor models, with contributions of 77.7 and 22.3% to the total concentrations of C4-C14- perfluoroalkyl carboxylic acids and PFOS, respectively. PMID:26947748

  7. Spatial distribution and source apportionment of PFASs in surface sediments from five lake regions, China

    NASA Astrophysics Data System (ADS)

    Qi, Yanjie; Huo, Shouliang; Xi, Beidou; Hu, Shibin; Zhang, Jingtian; He, Zhuoshi

    2016-03-01

    Perfluoroalkyl substances (PFASs) have been found in environment globally. However, studies on PFAS occurrence in sediments of lakes or reservoirs remain relatively scarce. In this study, two hundred and sixty-two surface sediment samples were collected from forty-eight lakes and two reservoirs all over China. Average PFAS concentrations in surface sediments from each lake or reservoir varied from 0.086 ng/g dw to 5.79 ng/g dw with an average of 1.15 ng/g dw. Among five lake regions, average PFAS concentrations for the lakes from Eastern Plain Region were the highest. Perfluorooctanoic acid, perfluoroundecanoic acid and perfluorooctane sulfonic acid (PFOS) were the predominant PFASs in surface sediments. The significant positive correlations between PFAS concentrations and total organic carbon, total nitrogen and total phosphorus contents in sediments revealed the influences of sedimentary characteristics on PFAS occurrence. A two-dimensional hierarchical cluster analysis heat map was depicted to analyze the possible origins of sediments and individual PFAS. The food-packaging, textile, electroplating, firefighting and semiconductor industry emission sources and the precious metals and coating industry emission sources were identified as the main sources by two receptor models, with contributions of 77.7 and 22.3% to the total concentrations of C4-C14- perfluoroalkyl carboxylic acids and PFOS, respectively.

  8. Seasonal and diurnal variations in methane emissions from Wuliangsu Lake in arid regions of China

    NASA Astrophysics Data System (ADS)

    Duan, Xiaonan; Wang, Xiaoke; Mu, Yujing; Ouyang, Zhiyun

    CH 4 emissions have been widely studied in various wetlands, such as boreal peatlands, rice paddies, and tropical swamps. However, little investigation has been carried out for CH 4 emissions from lakes or wetlands in arid regions where these freshwaters play a vital role in providing ecosystem services for local people. To quantify the spatial and temporal variations of CH 4 flux and understand its key controlling factors in shallow lakes in arid regions of Western China, CH 4 fluxes from Wuliangsu Lake were measured at different vegetation zones and water depths with a static chamber technique during a growing season from April to October in 2003. Results showed that the average emission flux of CH 4 from submerged plant ( Potamogeton pectinatus) growing zones was 2.16 mg CH 4 m -2 h -1, which was 85.8% lower than that from emergent macrophyte ( Phragmites australis) growing zones. CH 4 emissions increased with increasing water depth in Phragmites Community. Significant seasonal and diurnal variations of CH 4 emission were observed for P. australis during the plant growth stage, for P. pectinatus growing zones, however, the variations were minor. In addition to vegetation cover and water depth, bottom silt temperature and light intensity were also important factors influencing seasonal and diurnal variations of CH 4 flux from Phargmites growing zone.

  9. Malachite green and chloramphenicol in aquatic products from regions around Dongting Lake in Hunan, China.

    PubMed

    He, Jiang; Cui, Jingzhen

    2016-01-01

    Aquatic products are important sources of animal proteins in human diet, especially in developing countries. As such, the safety of aquatic products is of primary concern. In this study, a standard method is used to detect malachite green (MG) and chloramphenicol (CAP) and to analyse the contents of these banned chemicals in turtle, mandarin fish and grass carp sampled from the region surrounding Dongting Lake area in Hunan, China. Results showed that 10.6% of the samples were MG-positive, most of them turtles. CAP was found in 8.3% of the samples, mostly in mandarin fish. These data indicated that these banned substances are still used in the surveyed area. Hence, adequate strategies must be implemented by the local government to control these banned substances.

  10. Regional environmental change and human activity over the past hundred years recorded in the sedimentary record of Lake Qinghai, China.

    PubMed

    Sha, ZhanJiang; Wang, Qiugui; Wang, Jinlong; Du, Jinzhou; Hu, Jufang; Ma, Yujun; Kong, Fancui; Wang, Zhuan

    2017-03-01

    Environmental change and human activity can be recorded in sediment cores in aquatic systems such as lakes. Information from such records may be useful for environmental governance in the future. Six sediment cores were collected from Lake Qinghai, China and its sublakes during 2012 and 2013. Measurements of sediment grain-size fractions indicate that sedimentation in the north and southwest of Lake Qinghai is dominated by river input, whereas that in Lake Gahai and Lake Erhai is dominated by dunes. The sedimentation rates in Lake Qinghai were calculated to be 0.101-0.159 cm/y, similar to the rates in other lakes on the Qinghai-Tibetan Plateau. Using these data and sedimentation rates from the literature, we compiled the spatial distribution of sedimentation rates. Higher values were obtained in the three main areas of Lake Qinghai: two in river estuaries and one close to sand dunes. Lower values were measured in the center and south of the lake. Measurements of total organic carbon (TOC), total nitrogen (TN), phosphorus concentrations, and TOC/TN ratios in three cores (QH01, QH02, and Z04) revealed four horizons corresponding to times of increased human activity. These anthropogenic events were (1) the development of large areas of cropland in the Lake Qinghai watershed in 1960, (2) the beginning of nationwide fertilizer use and increases in cropland area in the lake watershed after 1970, (3) the implementation of the national program "Grain to Green," and (4) the rapid increase in the tourism industry from 2000. Profiles of Rb, Sr concentrations, the Rb/Sr ratio, and grain-size fraction in core Z04 indicate that the climate has become drier over the past 100 years. Therefore, we suggest that lake sediments such as those in Lake Qinghai are useful media for high-resolution studies of regional environmental change and human activity.

  11. Utah: Salt Lake Region

    Atmospheric Science Data Center

    2014-05-15

    article title:  Winter and Summer Views of the Salt Lake Region     View Larger Image Magnificent views of the region surrounding Salt Lake City, Utah are captured in these winter and summer images from the ...

  12. The farmers' perceptions of ANPS pollution and its influencing factors in Poyang Lake Region, China.

    PubMed

    Chen, Meiqiu; Chen, Mengjiao; Lu, Yanfei; Wang, Liguo; Huang, Yujiao

    2016-01-01

    Individual farmers represent the main management entities of agricultural production under the family-contract responsibility system in China, and thus play crucial roles in the prevention and control of agricultural nonpoint source (ANPS) pollution. The analysis of the farmers' perceptions of ANPS pollution as well as the factors affecting their perceptions can provide valuable information for relevant policy-making to preserve high quality water in Poyang Lake and regional quality of arable land. Through a survey titled 'Farmers' perceptions of ANPS pollution and farming behaviors in the Poyang Lake Region', the data related to the perceptions of farmers on ANPS pollution were collected. The factors that affect their awareness of ANPS pollution were identified with the method of boosted regression trees (BRT). The results indicated that the farmers had awareness of the risk of ANPS pollution to some extent, but they lacked adequate scientific knowledge. Generally, they had no consciousness about how to prevent and control ANPS pollution and did not understand techniques needed for proper scientifically sound application of fertilizers and pesticides. The main factors that influenced their perceptions of ANPS pollution are (from high to low): the ratio of total income which comes from farming, per capita farmland, age, education level, and household income. Some measures targeted to improve the prevention and control of ANPS pollution were proposed: developing modern agricultural techniques and promoting large-scale farming, increasing public campaigns related to ANPS pollution prevention and control with the goal of raising the level of awareness of farmers, and reforming the methods used to promote science and technology in agriculture and encourage the proper use of chemical fertilizers and pesticides.

  13. Large Water Management Projects and Schistosomiasis Control, Dongting Lake Region, China

    PubMed Central

    Li, Yue-Sheng; Zhao, Zheng-Yuan; He, Yong-Kang; Ellis, Magda K.; McManus, Donald P.

    2007-01-01

    Construction of the Three Gorges Dam across the Yangtze River will substantially change the ecology of the Dongting Lake in southern China. In addition, the Central and Hunan Provinces’ governmental authorities have instigated a Return Land to Lake Program that will extend the Dongting Lake surface area from the current 2,681 km2 to 4,350 km2.The previous construction of embankments and the large silt deposits made by the Yangtze River and other connecting rivers have contributed to frequent disastrous flooding. As a consequence of the 2 water projects, >2 million persons and their domestic animals are being resettled. This article provides an overview of the historical background of these 2 large water management projects, the associated population movement, and their impact on future transmission and control of schistosomiasis in the Dongting Lake area. The dam will likely substantially extend the range of the snail habitats and increase schistosome transmission and schistosomiasis cases. PMID:18214167

  14. Development stages of hazardous mountain lakes and simulation of their outbursts (Central Caucasus, Russia; Sichuan mountain region, China).

    NASA Astrophysics Data System (ADS)

    Kidyaeva, Vera; Krylenko, Inna; Chernomorets, Sergey; Petrakov, Dmitry

    2013-04-01

    The importance of mountain lakes studies is related to the increasing threat of natural disasters, associated with lake outbursts and debris flows formation, because of population growth on exposed areas. The outburst hazard has not been sufficiently researched, there is a lack of data because of the lakes inaccessibility and remote sensing data is usually not detailed enough. The main scientific topics include assessment of outburst possibility and further simulation of possible outbursts scenarios. There are two types of mountain lakes: glacial (cirque, cirque-moraine, barrier-moraine, glacial-barrier, etc.) lakes and barrier (landslide, rockfall, debris flow, etc.) lakes. The first type was studied in the Central Caucasus (Russia), and the second type - in the Sichuan mountain region (China). The group of scientists, including authors, has been monitoring glacial lakes in the Mnt. Elbrus area for more than ten years. The unique data were collected, including detailed hydrological characteristics of more than ten lakes (water level dynamics, temperature, morphometrical characteristics, water balance components, etc.). Outbursts of at least three glacial lakes were observed. Hydrological characteristics of landslide Tangjiashan Lake were collected with Chinese colleagues during field studies in 2010 and 2011 years. Analysis of the collected data was used to understand the outburst mechanisms, formation factors, dam breaking factors, development stages of mountain lakes. Statistical methods of analysis in this case can be applied with some limitations because of the lack of sufficient monitoring objects, and therefore the results has been verified by experts. All types of possible outbursts mechanisms were divided by the authors into five groups: geomorphologic (caused by changes in lake dams), seismic, or geodynamic (caused by seiches, waves from rockfalls, landslides), glacial (caused by breaks in impounding glaciers, ice floating and melting), water

  15. Identifying risk factors of avian infectious diseases at household level in Poyang Lake region, China.

    PubMed

    Jiang, Qian; Zhou, Jieting; Jiang, Zhiben; Xu, Bing

    2014-09-01

    Poultry kept in backyard farms are susceptible to acquiring and spreading infectious diseases because of free ranging and poor biosecurity measures. Since some of these diseases are zoonoses, this is also a significant health concern to breeders and their families. Backyard farms are common in rural regions of China. However, there is lack of knowledge of backyard poultry in the country. To obtain first-hand information of backyard poultry and identify risk factors of avian infectious diseases, a cross-sectional study was carried out at household level in rural regions around Poyang Lake. A door-to-door survey was conducted to collect data on husbandry practices, trading practices of backyard farmers, and surrounding environments of backyard farms. Farms were categorized into cases and controls based on their history of poultry death. Data were collected for 137 farms, and the association with occurrence of poultry death event was explored by chi-square tests. Results showed that vaccination implementation was a protective factor (odds ratio OR=0.40, 95% confidence interval CI: 0.20-0.80, p=0.01), while contact with other backyard flocks increased risk (OR=1.72, 95% CI: 0.79-3.74, p=0.16). A concept of "farm connectivity" characterized by the density of particular land-use types in the vicinity of the farm was proposed to characterize the degree of contact between poultry in one household farm and those in other household farms. It was found that housing density in a 20-m buffer zone of the farmhouse was most significantly associated with poultry death occurrence (OR=1.08, 95% CI: 1.02-1.17, p=0.03), and was in agreement with observation of villagers. Binary logistic regression was applied to evaluate the relationship between poultry death event and density of land-use types in all buffer zones. When integrated with vaccination implementation for poultry, prediction accuracy of poultry death event reached 72.0%. Results combining questionnaire survey with

  16. Changing land use and its impact on the habitat suitability for wintering Anseriformes in China's Poyang Lake region.

    PubMed

    Tang, Xuguang; Li, Hengpeng; Xu, Xibao; Yang, Guishan; Liu, Guihua; Li, Xinyan; Chen, Dongqiang

    2016-07-01

    As an internationally important wetland for migratory waterbirds, China's Poyang Lake region has experienced substantial changes in land use during the past two decades owing to climate change and anthropogenic disturbances. Recent dam constructions on the Yangtze River and its tributaries for agriculture and hydroelectric power exert strong effects on the hydrological regimes of this lake. However, few studies have investigated how the land-use changes through time affect the habitat suitability for wintering Anseriformes-the largest community in this region. Thus, it is necessary to timely monitor changes in the habitat quality and understand the potential factors that alter it. In this study, three periods (1995, 2005 and 2014) of typical environmental indicators that have direct impacts on foraging and resting for the Anserformes, including proximity to water (density of lakes, rivers and ponds), human disturbances (density of residences and various road networks), preferred land cover types and food availability (NDVI), are integrated to develop a habitat suitability index model for habitat mapping. The results indicate that long-term lake shrinkage in low-water periods led to greatly expanded wetlands in these years, which provided more suitable habitat for migratory waterfowl. The amount of highly suitable habitat in 2014 was nearly twice as much as in 1995. Recent survey data from 1997 to 2013 also revealed an increase in the population size, and confirmed the improvement of habitat suitability in the Poyang Lake region. Spatial analysis revealed that land use changes contributed most to the improved habitat coverage between 1995 and 2014. However, the relative significances of these transformations for highly suitable and moderately suitable habitats are strikingly different. Increases in wetland and paddy field area are the main reasons for explaining these improvements, respectively. The framework model proposed in this study will help governments to

  17. Genetic diversity of mitochondrial control region (D-Loop) polymorphisms in Coilia ectenes taihuensis inhabiting Taihu Lake, China.

    PubMed

    Zhang, J J; Duan, J R; Zhou, Y F; Peng, J Y; Fang, D A

    2017-03-16

    Coilia ectenes is a commercially important fishery species in China. C. ectenes taihuensis is an endemic and dominant species found in Taihu Lake of China. When compared with C. ectenes, C. ectenes taihuensis lacks anadromous behavior, and can independently grow and reproduce in Taihu Lake. In this study, the mitochondrial DNA control region (D-loop) sequences were employed to investigate the genetic diversity and population structure of C. ectenes taihuensis. Sixty-eight individuals collected from 4 localities in Taihu Lake were examined. Results indicated that in the 887-bp D-loop region, seventy-seven (8.68%) sites were variant, contributing to 53 distinct haplotypes. Although the population haplotype diversity (Hd = 0.971 to 1.000) was generally high, the nucleotide diversity (π = 0.616 to 0.731%) was relatively low among the 4 populations. Additionally, the genetic distances ranged from 0.62 to 0.74% within the populations and from 0.67 to 0.74% between the populations. The neighbor-joining tree indicated that a distinct distribution of phylogenetic structure existed among haplotypes. Analysis of molecular variance and FST statistics suggested that a divergence existed among populations in 4 localities, indicating that gene communication might have occurred among those populations. Furthermore, neutral tests and analysis of mismatch distribution reflected that C. ectenes taihuensis might have undergone a population expansion during the evolution process. Our study showed the population genetic diversity and structure of C. ectenes taihuensis. Results from this study might be helpful in the development and protection of fishery resource within the localities in Taihu Lake in future.

  18. Dongting Lake, China

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These images show dramatic change in the water at Dongting Lake in Hunan province, China. A flood crest surged down the Yangtze River in late August of this year, but the embankments made by residents there held. The left image was acquired on September 2, 2002 and shows the extent of the lake. The right image was obtained March 19, 2002 before the flooding began.

    These images were acquired on September 2, 2002 and March 19,2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is part of NASA's Earth Science Enterprise, a long-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as

  19. Immune factors and fatty acid composition in human milk from river/lake, coastal and inland regions of China.

    PubMed

    Urwin, Heidi J; Zhang, Jian; Gao, Yixiong; Wang, Chunrong; Li, Lixiang; Song, Pengkun; Man, Qingqing; Meng, Liping; Frøyland, Livar; Miles, Elizabeth A; Calder, Philip C; Yaqoob, Parveen

    2013-06-01

    Breast milk fatty acid composition may be affected by the maternal diet during gestation and lactation. The influence of dietary and breastmilk fatty acids on breast milk immune factors is poorly defined. We determined the fatty acid composition and immune factor concentrations of breast milk from women residing in river/lake, coastal and inland regions of China, which differ in their consumption of lean fish and oily fish. Breast milk samples were collected on days 3–5 (colostrum), 14 and 28 post-partum (PP) and analysed for soluble CD14 (sCD14), transforming growth factor (TGF)-b1, TGF-b2, secretory IgA (sIgA) and fatty acids. The fatty acid composition of breast milk differed between the regions and with time PP. The concentrations of all four immune factors in breast milk decreased over time, with sCD14, sIgA and TGF-b1 being highest in the colostrum in the river and lake region. Breast milk DHA and arachidonic acid (AA) were positively associated, and g-linolenic acid and EPA negatively associated, with the concentrations of each of the four immune factors. In conclusion, breast milk fatty acids and immune factors differ between the regions in China characterised by different patterns of fish consumption and change during the course of lactation. A higher breast milk DHA and AA concentration is associated with higher concentrations of immune factors in breast milk, suggesting a role for these fatty acids in promoting gastrointestinal and immune maturation of the infant.

  20. Phylogenetic analysis of Newcastle disease viruses isolated from wild birds in the Poyang Lake region of China.

    PubMed

    Fan, Shengtao; Wang, Tiecheng; Gao, Xiaolong; Ying, Ying; Li, Xue; Li, Yongcheng; Li, Yuanguo; Ma, Jinzhu; Sun, Heting; Chu, Dong; Xu, Yu; Yang, Songtao; Li, Qihan; Gao, Yuwei; Xia, Xianzhu

    2015-09-01

    Newcastle disease virus (NDV) causes a highly contagious viral disease in poultry and wild birds, and it can cause significant economic loss worldwide. Eight viral strains were isolated by inoculating embryonated chicken eggs from the Poyang Lake region of China with swab samples. All eight of the NDV isolates were identified as class I genotype 3 strains, but they diverged notablely from class II viruses. Further analysis revealed that all eight NDV isolates were lentogenic strains containing the (112)ERQER↓L(117) motif at the F protein cleavage site. The strains were highly identical and were more species specific (chicken and waterfowl) than site specific (Nanchang and Duchang regions). The close phylogenetic proximity of these isolates indicates that viral transmission may happen between poultry and wild birds. Our study demonstrates that lentogenic class I NDVs exist in clinically healthy wild waterfowl and poultry within the Poyang Lake region. Active surveillance of these viruses to determine their evolution and origin is one of the most realistic strategies for preventing and controlling NDV outbreaks.

  1. Land use investigation with remote sensing based on spectral character analyses in Poyang Lake region, China

    NASA Astrophysics Data System (ADS)

    Huang, Shu-e.; Wang, Baosheng; Wang, Huaiqing

    2004-01-01

    Based on Landsat TM data combined with practical investigation information obtained using Global Positioning Systems (GPS), we created a training field of land use classification. Using the methods of spectral distance analysis, we analyzed spectral signature value of different training fields in TM3, TM4, TM5 and TM7 band, and compared these with the standard deviation analysis. Based on these results, we selected the best spectral bands for classification and created remote sensing interpretation marks of land use classification. Supervising classification was used with the image classification of TM and the maximum likelihood was used for parametric rule of supervised classification. We applied the method of spectral signature analysis to the individual study of land use classification of Poyang Lake region. The land use was classified into 9 classes: paddy field, non-irrigated farmland, forestland, grassland, water area, lake beach, grass beach, sandy land and residential area. Based on the data of GPS investigation, we assessed the classification accuracy. Result indicated that classification accuracy reached 91.43% and the classification effect was better than the common supervised classifying and unsupervised classifying.

  2. Genetic variation between Schistosoma japonicum lineages from lake and mountainous regions in China revealed by resequencing whole genomes.

    PubMed

    Yin, Mingbo; Liu, Xiao; Xu, Bin; Huang, Jian; Zheng, Qi; Yang, Zhong; Feng, Zheng; Han, Ze-Guang; Hu, Wei

    2016-09-01

    Schistosoma infection is a major cause of morbidity and mortality worldwide. Schistosomiasis japonica is endemic in mainland China along the Yangtze River, typically distributed in two geographical categories of lake and mountainous regions. Study on schistosome genetic diversity is of interest in respect of understanding parasite biology and transmission, and formulating control strategy. Certain genetic variations may be associated with adaptations to different ecological habitats. The aim of this study is to gain insight into Schistosoma japonicum genetic variation, evolutionary origin and associated causes of different geographic lineages through examining homozygous Single Nucleotide Polymorphisms (SNPs) based on resequenced genome data. We collected S. japonicum samples from four sites, three in the lake regions (LR) of mid-east (Guichi and Tonglin in Anhui province, Laogang in Hunan province) and one in mountainous region (MR) (Xichang in Sichuan province) of south-west of China, resequenced their genomes using Next Generation Sequencing (NGS) technology, and made use of the available database of S. japonicum draft genomic sequence as a reference in genome mapping. A total of 14,575 SNPs from 2059 genes were identified in the four lineages. Phylogenetic analysis confirmed significant genetic variation exhibited between the different geographical lineages, and further revealed that the MR Xichang lineage is phylogenetically closer to LR Guich lineage than to other two LR lineages, and the MR lineage might be evolved from LR lineages. More than two thirds of detected SNPs were nonsynonymous; functional annotation of the SNP-containing genes showed that they are involved mainly in biological processes such as signaling and response to stimuli. Notably, unique nonsynonymous SNP variations were detected in 66 genes of MR lineage, inferring possible genetic adaption to mountainous ecological condition.

  3. The impact of educational videotapes on water contact behaviour of primary school students in the Dongting Lakes region, China.

    PubMed

    Yuan, L; Manderson, L; Tempongko, M S; Wei, W; Aiguo, P

    2000-08-01

    Multimedia has become increasingly important in educational programmes in schools in all societies, and has potential value for health education. We developed a video and a comic book on the transmission and prevention of schistosomiasis for use in primary schools in endemic areas of China. The material was designed to increase children's knowledge of schistosomiasis as an environmental disease and to encourage them to reduce their contact with unsafe water sources. To test the effectiveness of the video and booklet, a quasi-experimental study was conducted among 1,739 children in 50 primary schools in the Dongting Lake region. A self-administered questionnaire pre- and post-intervention showed a significant increase in knowledge about schistosomiasis in the intervention schools. Significantly, this change was associated with a decrease in contact with unsafe water sources, as established from water contact observations. This behavioural change suggests the value of short, targeted educational interventions to decrease risk of infection.

  4. Concentrations and potential health hazards of organochlorine pesticides in (shallow) groundwater of Taihu Lake region, China.

    PubMed

    Wu, Chunfa; Luo, Yongming; Gui, Tong; Huang, Yujuan

    2014-02-01

    A total of 27 shallow groundwater samples were collected from the Taihu Lake region (TLR), to determine the concentrations of 14 organochlorine pesticide (OCP) species, identify their possible sources, and estimate health risk of drinking the shallow groundwater. All OCP species occurred in the shallow groundwater of TLR with high detection frequency except p, p'-dichlorodiphenyldichlorothane (p, p'-DDD) and p, p'-dichlorodiphenyltrichloroethane (p, p'-DDT). DDTs and hexachlorocyclohexanes (HCHs) were the dominant OCP contaminants in the shallow groundwater of TLR, and they account for 44.2% total OCPs. The low α-HCH/γ-HCH ratio, high β-HCH/(α+γ)-HCH ratio and β-HCH being the dominant HCH isomers for the majority of samples suggest that the HCHs were mainly from the historical use of lindane after a period of degradation. p, p'-DDE being the dominant DDT metabolite for all the samples indicated that the DDTs were mainly from the historical residues. Compositional analysis also suggested that there were fresh input sources of heptachlors, aldrins and endrins in addition to the historical residues. Correlation analysis indicated the hexachlorobenzene (HCB) impurity in the shallow groundwater of TLR was likely from the historical application of lindane and technical HCH (a mixture of HCH isomers that is produced by photochlorination of benzene). Carcinogenic risk values for α-HCH, heptachlor, heptachlor epoxide, aldrins and dieldrin in the shallow groundwater in majority area of TLR were found to be >10(-6), posing a potentially serious cancer risk to those dependant on shallow groundwater for drinking water.

  5. Economic optimal nitrogen application rates for rice cropping in the Taihu Lake region of China: taking account of negative externalities

    NASA Astrophysics Data System (ADS)

    Xia, Y.; Yan, X.

    2011-07-01

    Nitrogen application rates (NARs) is often overestimated over the rice (Oryza sativa L.) growing season in the Taihu Lake region of China. This is largely because only individual nitrogen (N) losses are taken into account, or the inventory flows of reactive N have been limited solely to the farming process when evaluating environmental and economic effects of N fertilizer. Since N can permeate the ecosystem in numerous forms commencing from the acquisition of raw material, through manufacturing and use, to final losses in the farming process (e.g., N2O, NH3, NO3- leaching, etc.), the costs incurred also accumulate and should be taken into account if economically-optimal N rates (EONRs) are to be established. This study integrates important material and energy flows resulting from N use into a rice agricultural inventory that constitutes the hub of the life-cycle assessment (LCA) method. An economic evaluation is used to determine an environmental and economic NAR for the Taihu Lake region. The analysis reveals that production and exploitation processes consume the largest proportion of resources, accounting for 77.2 % and 22.3 % of total resources, respectively. Regarding environmental impact, global warming creates the highest cost with contributions stemming mostly from fertilizer production and raw material exploitation processes. Farming process incurs the biggest environmental impact of the three environmental impact categories considered, whereas transportation has a much smaller effect. When taking account of resource consumption and environmental cost, the marginal benefit of 1 kg rice would decrease from 2.4 to only 1.01 yuan. Accordingly, our current EONR has been evaluated at 185 kg N ha-1 for a single rice-growing season. This could enhance profitability, as well as reduce the N losses associated with rice growing.

  6. Winter runoff losses of phosphorus from paddy soils in the Taihu Lake Region of South China.

    PubMed

    Zhang, Huanchao; Cao, Zhihong; Wang, Gaiping; Zhang, Hongai; Wong, M H

    2003-09-01

    A winter wheat field plot experiment was conducted on two types of paddy soils, from November, 2000 to June, 2001 to assess P losses to its surrounding watercourses by runoff in the Taihu Lake Region. Commercial NPK compound fertilizer and single superphosphate fertilizer were applied to furnish 0, 20, 80, and 160 kg P ha(-1). The experiments consisted of six replicates of each treatment in Changshu site and four replicates in Anzhen site, with a plot size of 5x6 m2 in a randomized block design. Results revealed that the average concentration of dissolved P (DP), particulate P (PP), and total P (TP) in runoff water during the winter season was 0.13, 0.90 and 1.04 mg P l(-1) respectively, from P20 plots in Anzhen site. While it was 0.67, 1.08 and 1.75 mg P l(-1) respectively, from P20 plots in Changshu site. The seasonal TP load (mass loss) from P20 plot ranged from a low of 290.88 g P ha(-1)season(-1) to a high of 483.54 g P ha(-1)season(-1), with a mean of 382.29 g P ha(-1)season(-1) in Anzhen, but from 444.92 to 752.21 g P ha(-1)season(-1), with a mean of 539.13 g P ha(-1)season(-1) in Changshu. Both in Anzhen and Changshu PP represented a major portion of the TP lost in runoff, the average PP/TP was about more than 80% in P0 and P20 plot, but it was decreased with the increase of P rate. The average seasonal P loads (DP, PP, and TP) in Changshu were greater than in Anzhen although runoff volume in Anzhen (45 mm season(-1)) was more than in Changshu (36 mm season(-1)). This was probably associated with the differences of soil physical and chemical properties between the two sites. Phosphate fertilizer rate significantly affected P concentrations and P loads by runoff. Both the mean concentrations and the average seasonal P loads from the P80 plots were lower than from the P160 plots, but obviously higher than from the P20 and P0 plots. There was no significant difference found between the P20 plots and the P0 plots both in Anzhen and Changshu sites. It indicated

  7. Unified Scaling Law for Earthquakes: Seismic hazard and risk assessment for Himalayas, Lake Baikal, and Central China regions

    NASA Astrophysics Data System (ADS)

    Nekrasova, Anastasia; Kossobokov, Vladimir; Parvez, Imtiyaz; Tao, Xiaxin

    2015-04-01

    The Unified Scaling Law for Earthquakes (USLE), that generalizes the Gutenberg-Richter recurrence relation, has evident implications since any estimate of seismic hazard depends on the size of the territory that is used for investigation, averaging, and extrapolation into the future. Therefore, the hazard may differ dramatically when scaled down to the proportion of the area of interest (e.g. territory occupied by a city) from the enveloping area of investigation. In fact, given the observed patterns of distributed seismic activity the results of multi-scale analysis embedded in USLE approach demonstrate that traditional estimations of seismic hazard and risks for cities and urban agglomerations are usually underestimated. Moreover, the USLE approach provides a significant improvement when compared to the results of probabilistic seismic hazard analysis, e.g. the maps resulted from the Global Seismic Hazard Assessment Project (GSHAP). We apply the USLE approach to evaluating seismic hazard and risks to population of the three territories of different size representing a sub-continental and two different regional scales of analysis, i.e. the Himalayas and surroundings, Lake Baikal, and Central China regions.

  8. [Estimating of decadal accumulation rates of heavy metals in surface rice soils in the Tai Lake region of China].

    PubMed

    Li, Lianqing; Pan, Genxing; Zhang, Pingjiu; Cheng, Jiemin; Zhu, Qiuhua; Qiu, Duosheng

    2002-05-01

    Estimation of decadal accumulation of some heavy metals in surface rice soils from the Tai Lake region, southern Jiangsu Province, China was made by means of calculating the monitoring data and/or analysis data of the archived soil samples. For the last decade, the estimated annual accumulation rate for Cu or Zn, Pb and Cd was 0.3-1 mg.(kg.a)-1, 0.2-1 mg.(kg.a)-1 and 0.3-3 micrograms.(kg.a)-1 respectively, the apparent pollution loading was, therefore, respectively 0.5-1 kg.(hm2.a)-1, 0.5-1.0 kg.(hm2.a)-1, 0.5-3.0 kg.(hm2.a)-1 [symbol: see text] 0.8-10 x 10(-3) kg.(hm2.a)-1. The accumulation rate for the content of available form was shown to be greater than that of total content. The non-point source pollution marked bigger contribution to the total annual loading for the Pb and Cd than the other source pollutions, while the Cd loading was prominently higher than those reported in Europe. These results may indicate that the food safety in this region may be constrained by the soil pollution of these heavy metals at high accumulation rates.

  9. Response of sediment calcium and magnesium species to the regional acid deposition in eutrophic Taihu Lake, China.

    PubMed

    Tao, Yu; Dan, Dai; Chengda, He; Qiujin, Xu; Fengchang, Wu

    2016-11-01

    Acid deposition causes carbonate dissolution in watersheds and leads to profound impacts on water chemistry of lakes. Here, we presented a detailed study on the seasonal, spatial, and vertical variations of calcium and magnesium species in the overlying water, interstitial water, and sediment profiles in eutrophic Taihu Lake under the circumstance of regional acid deposition. The result showed that both the acid deposition and biomineralization in Taihu Lake had effects on Ca and Mg species. In the lake water, calcium carbonate was saturated or over-saturated based on long-term statistical calculation of the saturation index (SI). On the sediment profiles, significant difference in Ca and Mg species existed between the surface sediment (0-10 cm) and deeper sediments (>10 cm). The interstitial water Ca(2+) and Mg(2+), ion-exchangeable Ca and Mg in the surface sediment were higher than those in the deeper sediment. In the spring, when the acid deposition is more intensive, the acid-extracted Ca and Mg in the surface sediment were lower than that in the deeper sediment in the northwest lake, due to carbonate dissolution caused by the regional acid deposition. Spatially, the higher concentration of acid-extracted Ca and Mg in the northwest surface sediment than that in the east lake was observed, indicating the pronounced carbonate biomineralization by algae bloom in the northwest lake. Statistical analysis showed that acid deposition exerted a stronger impact on the variation of acid-extracted Ca and Mg in the surface sediment than the biomineralization in Taihu Lake. For the total Ca and Mg concentration in the spring, however, no significant change between the surface and deeper sediment in the northwest lake was observed, indicating that the carbonate precipitation via biomineralization and the carbonate dissolution due to acidic deposition were in a dynamic balance. These features are of major importance for the understanding of combined effects of acid

  10. Genetic characterization of H9N2 avian influenza virus in plateau pikas in the Qinghai Lake region of China.

    PubMed

    Yan, Yan; Gu, Jin-Yan; Yuan, Zhuang-Chuan; Chen, Xin-Yu; Li, Zeng-Kui; Lei, Jing; Hu, Bo-Li; Yan, Li-Ping; Xing, Gang; Liao, Min; Zhou, Ji-Yong

    2017-04-01

    Qinghai Lake is a major migratory-bird breeding site that has experienced several highly pathogenic avian influenza virus (AIV) epizootics. Plateau pikas (Ochotona curzoniae) have previously been implicated in the ecology of avian influenza virus in this region. We first isolated an H9N2 AIV (A/Pika/Menyuan/01/2008) from plateau pikas between November 2008 and October 2009. Sequence analysis showed that the A/Pika/Menyuan/01/2008 AIV was closely related to the H9N2 AIV strain (A/Turkey/Wisconsin/ 1/1966). Our findings suggested that plateau pikas may contribute to AIV epidemiology in the Qinghai Lake region.

  11. Indicator Development for Potential Presence of Schistosomiasis Japonicum's Vector in Lake and Marshland Regions- A Case Study of Poyang Lake, Jiangxi Province, P.R. China

    NASA Astrophysics Data System (ADS)

    Marie, Tiphanie; Yesou, Herve; Huber, Claire; De Fraipont, Paul; Uribe, Carlos; Lacaux, Jean-Pierre; Lafaye, Murielle; Lai, Xijun; Desnos, Yves-Louis

    2013-01-01

    Earth observation data and bibliography on environmental parameters were used for mapping Oncomelania hupensis distribution, the Schistosomiasis japonicum’s intermediate host snail, within Poyang Lake (Jiangxi Province, P.R. China). Areas suitable for the development of O. hupensis, the vector of schistosomiasis, were derived from submersion time parameters and vegetation community indicators. ENVISAT time series data acquired from 2000 to 2009 were used for submersion times mapping, and 5 Beijing-1 data acquired during the dry season between 2006 and 2008 were used to map suitable vegetation for vector development. Yearly maps obtained indicate four principally potential endemic areas: the Gan Delta, the bank of the Fu He River, the Dalianzi Hu sector and the Poyang Lake Nature Reserve. Monthly maps from December 2005 to December 2008 show the dynamic of potential O. hupensis presence areas.

  12. Seasonal variation and controlling factors of anaerobic ammonium oxidation in freshwater river sediments in the Taihu Lake region of China.

    PubMed

    Zhao, Yongqiang; Xia, Yongqiu; Kana, Todd M; Wu, Yucheng; Li, Xiaobo; Yan, Xiaoyuan

    2013-11-01

    Anaerobic ammonium oxidation (anammox) has been recently recognized as an important pathway for the removal of fixed nitrogen (N) from aquatic systems. However, the functions of anammox in freshwater river systems remain uncertain. In this study, we evaluated the occurrence of anammox activity in two rivers in the Taihu Lake region in China during a seasonal survey. Homogenized sediments were incubated with (15)N-labeled NO3(-) and NH4(+) amendments to determine the potential importance of the anammox process relative to canonical denitrification. Production of (29)N2 and (30)N2 in slurries was determined using membrane inlet mass spectrometry. Potential anammox rates in the two river sediments ranged from 0.11±0.07 to 6.79±1.28 μmol N m(-2) h(-1) and the remove of N by anammox accounted for 0.8±0.00% to 10.7±0.03% of total N2 production. Potential anammox rates varied spatially and temporally in the two rivers, with the highest and lowest mean anammox rates appearing during summer and early autumn and during winter, respectively. The variation of the percentage of anammox to total N2 production displayed the same trend with potential anammox rates. Water temperature and NO3(-) content in sediments were the main factors affecting anammox activity. Anammox bacteria were detected in sediment samples using barcode pyrosequencing. The 16S rRNA anammox gene sequences in the river sediments were affiliated with Candidatus Kuenenia, Candidatus Jettenia, and Candidatus Scalindua, among which C. Kuenenia dominated the anammox bacterial communities. Our results confirmed the presence of anammox bacteria but their role is relatively small in removing fixed N from freshwater river systems.

  13. Restoration in northern Lake Gehu, a eutrophic lake in China

    NASA Astrophysics Data System (ADS)

    Wu, Xiaodong; Li, Wenchao; Pan, Jizheng; Ma, Shuzhan; Chen, Bingfa; He, Shangwei

    2017-02-01

    Lake Gehu is a severely eutrophic lake in southeast China. A series of restoration measures have been implemented since 2009 in northern Lake Gehu. This study compared aquatic plants, water quality, sediment, and phytoplankton between restoration and control areas to investigate the effect of restoration measures. The results demonstrated that aquatic macrophyte coverage increased from 0% to 10.6%; mean TP, TN, and CODMn concentrations increased by 50.0%, 42.4%, and 40.8%, respectively, compared with those before the measures were carried out; the mean Secchi depth (SD) increased to 42.5 cm, which is 1.4 times higher than that before restoration; the mean euphotic depth (Zeu) in the summer increased from 91 to 130 cm; the mean chl a concentration decreased from 34.8 to 20.2 μg/L, compared with that before restoration; the Shannon-Wiener index of phytoplankton increased by 28.7%. The mean TP and TN concentrations in sediments decreased by 63.8% and 52.4%, respectively, compared with that before dredging. These results indicate that the restoration in northern Lake Gehu was effective. To complete the transformation from an algae- to a macrophyte-stable state within the region, further measures must be adopted. This restoration of a eutrophic lake can serve as a reference for similar eutrophic lakes.

  14. Microplastics in Taihu Lake, China.

    PubMed

    Su, Lei; Xue, Yingang; Li, Lingyun; Yang, Dongqi; Kolandhasamy, Prabhu; Li, Daoji; Shi, Huahong

    2016-09-01

    In comparison with marine environments, the occurrence of microplastics in freshwater environments is less understood. In the present study, we investigated microplastic pollution levels during 2015 in Taihu Lake, the third largest Chinese lake located in one of the most developed areas of China. The abundance of microplastics reached 0.01 × 10(6)-6.8 × 10(6) items/km(2) in plankton net samples, 3.4-25.8 items/L in surface water, 11.0-234.6 items/kg dw in sediments and 0.2-12.5 items/g ww in Asian clams (Corbicula fluminea). The average abundance of microplastics was the highest in plankton net samples from the southeast area of the lake and in the sediments from the northwest area of the lake. The northwest area of the lake was the most heavily contaminated area of the lake, as indicated by chlorophyll-α and total phosphorus. The microplastics were dominated by fiber, 100-1000 μm in size and cellophane in composition. To our best knowledge, the microplastic levels measured in plankton net samples collected from Taihu Lake were the highest found in freshwater lakes worldwide. The ratio of the microplastics in clams to each sediment sample ranged from 38 to 3810 and was negatively correlated to the microplastic level in sediments. In brief, our results strongly suggest that high levels of microplastics occurred not only in water but also in organisms in Taihu Lake.

  15. Risk Transmission Indicator of Schistosomiasis Japonicum Considering Human Activities in Lake and Marshland Regions- A Case Study of Poyang Lake, Jiangxi Province, P.R. China

    NASA Astrophysics Data System (ADS)

    Marie, Tiphanie; Yesou, Herve; Huber, Claire; De Fraipont, Paul; Uribe, Carlos; Lacaux, Jean-Pierre; Lafaye, Murielle; Lai, Xijun; Desnos, Yves-Louis

    2013-01-01

    This paper present the method used to determine the areas where schistosomiasis transmission is the higher. A primary work was necessary to this study: identification of potential presence of schistosomiasis japonicum’s vector in Poyang lakeshore area (Jiangxi Province, P.R. China). Results obtained from its first work were crossing with the most risky human activities and with villages to elaborate a level of transmission risk. The first parameter determined concern fishing, which was identified like the most risky activity for schistosomiasis transmission, and fish traps were digitalized using a very high resolution ALOS data. The second parameter is about the risky areas for buffalo grazing, and vector potential presence areas were crossed with village proximity to determine the most risky areas for human transmission. The third parameter built is a level of risk for each village digitalized around Poyang Lake, taking into account the proximity and level of potential presence of vector’s areas.

  16. Field scale interaction and nutrient exchange between surface water and shallow groundwater in the Baiyang Lake region, North China Plain.

    PubMed

    Brauns, Bentje; Bjerg, Poul L; Song, Xianfang; Jakobsen, Rasmus

    2016-07-01

    Fertilizer input for agricultural food production, as well as the discharge of domestic and industrial water pollutants, increases pressures on locally scarce and vulnerable water resources in the North China Plain. In order to: (a) understand pollutant exchange between surface water and groundwater, (b) quantify nutrient loadings, and (c) identify major nutrient removal pathways by using qualitative and quantitative methods, including the geochemical model PHREEQC) a one-year study at a wheat (Triticum aestivum L.) and maize (Zea mays L.) double cropping system in the Baiyang Lake area in Hebei Province, China, was undertaken. The study showed a high influence of low-quality surface water on the shallow aquifer. Major inflowing pollutants into the aquifer were ammonium and nitrate via inflow from the adjacent Fu River (up to 29.8mg/L NH4-N and 6.8mg/L NO3-N), as well as nitrate via vertical transport from the field surface (up to 134.8mg/L NO3-N in soil water). Results from a conceptual model show an excess nitrogen input of about 320kg/ha/a. Nevertheless, both nitrogen species were only detected at low concentrations in shallow groundwater, averaging at 3.6mg/L NH4-N and 1.8mg/L NO3-N. Measurement results supported by PHREEQC-modeling indicated cation exchange, denitrification, and anaerobic ammonium oxidation coupled with partial denitrification as major nitrogen removal pathways. Despite the current removal capacity, the excessive nitrogen fertilization may pose a future threat to groundwater quality. Surface water quality improvements are therefore recommended in conjunction with simultaneous monitoring of nitrate in the aquifer, and reduced agricultural N-inputs should be considered.

  17. [Effects of different rotation systems on greenhouse gas (CH₄ and N₂O) emissions in the Taihu Lake region, China].

    PubMed

    Hu, An-yong; Sun, Xing; Liu, Qin

    2016-01-01

    We conducted a greenhouse gas emissions study of different rice-based cropping systems in the Taihu Lake region. The results indicated that the seasonal CH₄ emission initially increased, but declined over time. CH₄emission mainly occurred during the early stages of rice growth and decreased after the paddy soil dried. N₂O emission mainly occurred during the fertilizer application and paddy field drying stages. Compared with N20 emission, CH₄ emission contributed significantly more to the global warming potential (GWP) during the rice season. The proportion of CH4 emission to the total greenhouse gas emissions, which this study aimed to reduce, ranged from 94.7%-99.6%. CH₄emissions and their GWP during the rice season varied significantly under different rotation systems, with the order of wheat-rice rotation>Chinese milk vetch-rice rotation>fallow-rice rotation, while the N2O emissions and their GWP exhibited no significant differences. Compared with no nitrogen fertilization, applying N fertilizer significantly reduced CH₄ emission and GWP of the Chinese milk vetch-rice rotation. However, CH₄ emission and GWP did not vary with N application rates. The rice yield was largest when the N application rate was 240 kg · hm⁻². Taking economic and environmental benefits into account, we found that a N application rate of 240 kg · hm⁻² and a straw-return application of Chinese milk vetch not only reduced greenhouse gas emissions but also achieved the highest rice grain yield, which was recommended as a suitable cropping system for the Taihu Lake region.

  18. Does Landscape Fragmentation Influence Sex Ratio of Dioecious Plants? A Case Study of Pistacia chinensis in the Thousand-Island Lake Region of China

    PubMed Central

    Yu, Lin; Lu, Jianbo

    2011-01-01

    The Thousand-Island Lake region in Zhejiang Province, China is a highly fragmented landscape with a clear point-in-time of fragmentation as a result of flooding to form the reservoir. Islands in the artificial lake were surveyed to examine how population sex ratio of a dioecious plant specie Pistacia chinensis B. was affected by landscape fragmentation. A natural population on the mainland near the lake was also surveyed for comparison. Population size, sex ratio and diameter at breast height (DBH) of individuals were measured over 2 years. More than 1,500 individuals, distributed in 31 populations, were studied. Soil nitrogen in the different populations was measured to identify the relationship between sex ratio and micro-environmental conditions. In accordance with the results of many other reports on biased sex ratio in relation to environmental gradient, we found that poor soil nitrogen areas fostered male-biased populations. In addition, the degree of sex ratio bias increased with decreasing population size and population connectivity. The biased sex ratios were only found in younger individuals (less than 50 years old) in small populations, while a stable 1∶1 sex ratio was found in the large population on the mainland. We concluded that the effects of landscape fragmentation on the dioecious population sex ratio were mainly achieved in relation to changing soil nitrogen conditions in patches and pollen limitation within and among populations. Large populations could maintain a more suitable environment in terms of nutrient conditions and pollen flow, subsequently maintaining a stable sex ratio in dioecious plant populations. Both micro-environmental factors and spatial structure should be considered in fragmented landscape for the conservation of dioecious plant species. PMID:21829667

  19. Microbial profiles of a drinking water resource based on different 16S rRNA V regions during a heavy cyanobacterial bloom in Lake Taihu, China.

    PubMed

    Zhang, Junyi; Zhu, Congming; Guan, Rui; Xiong, Zhipeng; Zhang, Wen; Shi, Junzhe; Sheng, Yi; Zhu, Bingchuan; Tu, Jing; Ge, Qinyu; Chen, Ting; Lu, Zuhong

    2017-03-31

    Understanding of the bacterial community structure in drinking water resources helps to enhance the security of municipal water supplies. In this study, bacterial communities were surveyed in water and sediment during a heavy cyanobacterial bloom in a drinking water resource of Lake Taihu, China. A total of 325,317 high-quality sequences were obtained from different 16S ribosomal RNA (rRNA) regions (V3, V4, and V6) using the Miseq sequencing platform. A notable difference was shown between the water and sediment samples, as predominated by Cyanobacteria, Proteobacteria, and Actinobacteria in the water and Proteobacteria, Chloroflexi, and Verrucomicrobia in the sediment, respectively. The LD12 family dominated the water surface and was tightly associated with related indicators of cyanobacterial propagation, indicating involvement in the massive proliferation of cyanobacterial blooms. Alternatively, the genus Nitrospira dominated the sediment samples, which indicates that nitrite oxidation was very active in the sediment. Although pathogenic bacteria were not detected in a large amount, some genera such as Mycobacterium, Acinetobacter, and Legionella were still identified but in very low abundance. In addition, the effects of different V regions on bacterial diversity survey were evaluated. Overall, V4 and V3 were proven to be more promising V regions for bacterial diversity survey in water and sediment samples during heavy water blooms in Lake Taihu, respectively. As longer, cheaper, and faster DNA sequencing technologies become more accessible, we expect that bacterial community structures based on 16S rRNA amplicons as an indicator could be used alongside with physical and chemical indicators, to conduct comprehensive assessments for drinking water resource management.

  20. Spatial heterogeneity of lake eutrophication caused by physiogeographic conditions: An analysis of 143 lakes in China.

    PubMed

    Ding, Jingtao; Cao, Jinling; Xu, Qigong; Xi, Beidou; Su, Jing; Gao, Rutai; Huo, Shouliang; Liu, Hongliang

    2015-04-01

    In order to identify the effect of geographic characteristics on the variations of nutrient concentrations and the utilization efficiency of nutrients by phytoplankton, data from 143 lakes, from 2008 to 2010, including three very different types of topography, i.e., the first topography ladder (FTL), second topography ladder (STL), and third topography ladder (TTL), were statistically analyzed. Lakes in the FTL and STL, located at high elevation (above 1000 m) and low longitudes (lower than 105° E), were sporadically oligotrophic, whereas lakes in the TTL were almost all mesotrophic and eutrophic. The trophic level index (TLI) became higher with the rise of longitude. Two turning points (5 and 15°C) on the curve of TLI as function of the average annual temperature (AAT) corresponded with the AAT in different lake regions in the STL and TTL. Because the responses of TLI to AAT differ significantly, there were variations of nutrient and algal biomass concentrations in different lake regions in the same type of topography ladder. According to the differences in utilization efficiency of total nitrogen or total phosphorus by phytoplankton, China could be partitioned into six lake regions. Scientific nutrient criteria for each lake region shall be established considering these differences in China.

  1. Genotypes of ITS region of rRNA in Microcystis (Cyanobacteria) populations in Erhai Lake (China) and their correlation with eutrophication level.

    PubMed

    Song, Gaofei; Jiang, Yongguang; Yu, Gongliang; Li, Renhui

    2015-10-01

    Previous studies on spatiotemporal changes of Microcystis genotypes have shown that the existence and succession of dominant genotypes always occur in eutrophicated freshwater bodies. However, few studies have focused on the correlation between genotype composition and eutrophication level. In the present study, clone libraries of the internal transcribed spacer (ITS) of rrn operon were sequenced from Microcystis populations in Erhai Lake, a subtropical plateau lake in the preliminary eutrophication stage. The genotype composition of the Microcystis populations was highly variable at spatiotemporal scales, and 473 ITS genotypes were identified from the 800 ITS sequences obtained. However, no significantly dominant ITS genotypes existed in the lake. Comparison of Erhai Lake with four major lakes in China, namely, Taihu, Chaohu, Gucheng, and Shijiu Lakes, showed that the Microcystis ITS genotypes and genetic diversity were negatively correlated with eutrophication level. Extensive comparison of the Microcystis ITS genotypes from waters worldwide revealed that 440 ITS genotypes were unique to Erhai Lake, and no obvious phylogenetic correlations can be detected among the dominant genotypes from different water bodies. The high genetic diversity of the Microcystis populations in Erhai Lake may have resulted from the effect of the early stage of eutrophication.

  2. Linking sedimentary total organic carbon to (210)Pbex chronology from Changshou Lake in the Three Gorges Reservoir Region, China.

    PubMed

    Anjum, Raheel; Gao, Jinzhang; Tang, Qiang; He, Xiubin; Zhang, Xinbao; Long, Yi; Shi, Zhonglin; Wang, Mingfeng

    2017-05-01

    The influences of total organic carbon (TOC) and total nitrogen (TN) on Lead-210 ((210)Pb) dating have recently been of increasing concern in lacustrine research. Sediment core from Changshou Lake in the Longxi catchment was investigated for influence of TOC on (210)Pb dating. Lead-210 excess ((210)Pbex), Cesium-137 ((137)Cs) activities, TOC, TN, and particle size were measured. We proposed a dating index based on (137)Cs chronology and particle size distribution of the lake sediment profile and rainfall erosivities calculated from Longxi catchment metrological records. Increasing trends in TOC and TN were specifically caused by commercial cage fish farming after 1989. The statistically significant correlation between (210)Pbex activity, TOC (0.61, p = 0.04) and TN (0.51, p = 0.04), respectively explained post-1989 (210)Pb scavenging. The (210)Pbex activity was closely related with coupled peaks of TOC and TN from mass depth 5-10 g cm(-2). Higher TOC/TN ratio (8.33) indicated submerged macrophytes and native aquatic algal growth as main source of carbon from enhanced primary productivity because of massive fertilizer use and coherent climate warming. The study supported key hypothesis on vital role of fertilizer usage and algal derived TOC in controlling sedimentary (210)Pbex activity at Changshou Lake sediment. (137)Cs profile and erosive events as time markers provided reliable and consistent sedimentation rate of (1.6 cm y(-1)). (210)Pbex activity decayed exponentially after peak at mass depth 5.68 g cm(-2). Therefore, violation of (210)Pb dating primary assumptions made it inappropriate for sediment dating at Changshou Lake. TOC content must be considered while using (210)Pb as dating tool for lake sediment profiles.

  3. [Natural environment and schistosomiasis transmission in Poyang Lake region].

    PubMed

    Lv, Shang-Biao; Lin, Dan-Dan

    2014-10-01

    Schistosomiasis is closely related to natural environmental factors. The changes of environmental factors, such as temperature, hydrology, vegetation, soil etc., all impact the scope and extent of schistosomiasis transmission. Poyang Lake is the largest freshwater lake and one of the major endemic areas with schistosomiasis in China. With global warming, the implementation of the Three Gorges Dam operation, and the Poyang Lake Ecological Economic Planning, the natural environment in Poyang Lake area has been and will continue to change, especially, the water environment and climate environment, which are more closely related to the schistosomiasis transmission. These changes, to some extent, have affected and will continue to affect the prevalence and transmission of schistosomiasis. This article reviews the relationship between the natural environment and its changes and schistosomiasis transmission in the Poyang Lake region.

  4. Mapping rice cropping systems using Landsat-derived Renormalized Index of Normalized Difference Vegetation Index (RNDVI) in the Poyang Lake Region, China

    NASA Astrophysics Data System (ADS)

    Li, Peng; Jiang, Luguang; Feng, Zhiming; Sheldon, Sage; Xiao, Xiangming

    2016-06-01

    Mapping rice cropping systems with optical imagery in multiple cropping regions is challenging due to cloud contamination and data availability; development of a phenology-based algorithm with a reduced data demand is essential. In this study, the Landsat-derived Renormalized Index of Normalized Difference Vegetation Index (RNDVI) was proposed based on two temporal windows in which the NDVI values of single and early (or late) rice display inverse changes, and then applied to discriminate rice cropping systems. The Poyang Lake Region (PLR), characterized by a typical cropping system of single cropping rice (SCR, or single rice) and double cropping rice (DCR, including early rice and late rice), was selected as a testing area. The results showed that NDVI data derived from Landsat time-series at eight to sixteen days captures the temporal development of paddy rice. There are two key phenological stages during the overlapping growth period in which the NDVI values of SCR and DCR change inversely, namely the ripening phase of early rice and the growing phase of single rice as well as the ripening stage of single rice and the growing stage of late rice. NDVI derived from scenes in two temporal windows, specifically early August and early October, was used to construct the RNDVI for discriminating rice cropping systems in the polder area of the PLR, China. Comparison with ground truth data indicates high classification accuracy. The RNDVI approach highlights the inverse variations of NDVI values due to the difference of rice growth between two temporal windows. This makes the discrimination of rice cropping systems straightforward as it only needs to distinguish whether the candidate rice type is in the period of growth (RNDVI<0) or senescence (RNDVI>0).

  5. Carbon accumulation and sequestration of lakes in China during the Holocene.

    PubMed

    Wang, Mei; Chen, Huai; Yu, Zicheng; Wu, Jianghua; Zhu, Qiu'an; Peng, Changhui; Wang, Yanfen; Qin, Boqiang

    2015-12-01

    Understanding the responses of lake systems to past climate change and human activity is critical for assessing and predicting the fate of lake carbon (C) in the future. In this study, we synthesized records of the sediment accumulation from 82 lakes and of C sequestration from 58 lakes with direct organic C measurements throughout China. We also identified the controlling factors of the long-term sediment and C accumulation dynamics in these lakes during the past 12 ka (1 ka = 1000 cal yr BP). Our results indicated an overall increasing trend of sediment and C accumulation since 12 ka, with an accumulation peak in the last couple of millennia for lakes in China, corresponding to terrestrial organic matter input due to land-use change. The Holocene lake sediment accumulation rate (SAR) and C accumulation rate (CAR) averaged (mean ± SE) 0.47 ± 0.05 mm yr(-1) and 7.7 ± 1.4 g C m(-2)  yr(-1) in China, respectively, comparable to the previous estimates for boreal and temperate regions. The SAR for lakes in the East Plain of subtropical China (1.05 ± 0.28 mm yr(-1) ) was higher than those in other regions (P < 0.05). However, CAR did not vary significantly among regions. Overall, the variability and history of climate and anthropogenic interference regulated the temporal and spatial dynamics of sediment and C sequestration for lakes in China. We estimated the total amount of C burial in lakes of China as 8.0 ± 1.0 Pg C. This first estimation of total C storage and dynamics in lakes of China confirms the importance of lakes in land C budget in monsoon-influenced regions.

  6. Dynamics of soil available phosphorus and its impact factors under simulated climate change in typical farmland of Taihu Lake region, China.

    PubMed

    Yu, Kaihao; Chen, Xiaomin; Pan, Genxing; Zhang, Xuhui; Chen, Can

    2016-02-01

    Global climate change affects the availability of soil nutrients, thereby influencing crop productivity. This research was conducted to investigate the effects of elevated CO2, elevated temperature, and the interaction of the elevated CO2 and temperature on the soil available phosphorus (P) of a paddy-wheat rotation in the Taihu Lake region, China. Winter wheat (Triticum aestivum L.) was cultivated during the study period from 2011 to 2014 at two CO2 levels (350 μL•L(-1) ambient and 500 μL•L(-1) elevated by 150 μL•L(-1)) and two temperatures (ambient and 2 °C above the ambient). Soil available P content increased at the first season and decreased at the last season during the three wheat growing seasons. Soil available P content showed seasonal variation, whereas dynamic changes were not significant within each growing season. Soil available P content had no obvious trends under different treatments. But for the elevated temperature, CO2, and their combination treatments, soil available P content decreased in a long time period. During the period of wheat ripening stage, significant positive correlations were found between soil available P content and saturated hydraulic conductivity (Ks) and organic matter, but significant negative correlations with soil clay content and pH value; the correlation coefficients were 0.9400 (p < 0.01), 0.9942 (p < 0.01), -0.9383 (p < 0.01), and -0.6403 (p < 0.05), respectively. Therefore, Ks, organic matter, soil clay, and pH were the major impact factors on soil available P content. These results can provide a basis for predicting the trend of soil available P variation, as well as guidance for managing the soil nutrients and best fertilization practices in the future climate change scenario.

  7. Detection of Critical LUCC Indices and Sensitive Watershed Regions Related to Lake Algal Blooms: A Case Study of Taihu Lake

    PubMed Central

    Lin, Chen; Ma, Ronghua; Su, Zhihu; Zhu, Qing

    2015-01-01

    Taihu Lake in China has suffered from severe eutrophication over the past 20 years which is partly due to significant land use/cover change (LUCC). There is an increasing need to detect the critical watershed region that significantly affects lake water degradation, which has great significance for environmental protection. However, previous studies have obtained conflicting results because of non–uniform lake indicators and inadequate time periods. To identify the sensitive LUCC indices and buffer distance regions, three lake divisions (Meiliang Lake, Zhushan Lake and Western Coastal region) and their watershed region within the Taihu Lake basin were chosen as study sites, the algal area was used as a uniform lake quality indicator and modeled with LUCC indices over the whole time series. Results showed that wetland (WL) and landscape index such as Shannon diversity index (SHDI) appeared to be sensitive LUCC indices when the buffer distance was less than 5 km, while agricultural land (AL) and landscape fragmentation (Ci) gradually became sensitive indices as buffer distances increased to more than 5 km. For the relationship between LUCC and lake algal area, LUCC of the WC region seems to have no significant effect on lake water quality. Conversely, LUCC within ML and ZS region influenced algal area of corresponding lake divisions greatly, while the most sensitive regions were found in 3 km to 5 km, rather than the whole catchment. These results will be beneficial for the further understanding of the relationship between LUCC and lake water quality, and will provide a practical basis for the identification of critical regions for lake. PMID:25642691

  8. Detection of critical LUCC indices and sensitive watershed regions related to lake algal blooms: a case study of Taihu Lake.

    PubMed

    Lin, Chen; Ma, Ronghua; Su, Zhihu; Zhu, Qing

    2015-01-29

    Taihu Lake in China has suffered from severe eutrophication over the past 20 years which is partly due to significant land use/cover change (LUCC). There is an increasing need to detect the critical watershed region that significantly affects lake water degradation, which has great significance for environmental protection. However, previous studies have obtained conflicting results because of non-uniform lake indicators and inadequate time periods. To identify the sensitive LUCC indices and buffer distance regions, three lake divisions (Meiliang Lake, Zhushan Lake and Western Coastal region) and their watershed region within the Taihu Lake basin were chosen as study sites, the algal area was used as a uniform lake quality indicator and modeled with LUCC indices over the whole time series. Results showed that wetland (WL) and landscape index such as Shannon diversity index (SHDI) appeared to be sensitive LUCC indices when the buffer distance was less than 5 km, while agricultural land (AL) and landscape fragmentation (Ci) gradually became sensitive indices as buffer distances increased to more than 5 km. For the relationship between LUCC and lake algal area, LUCC of the WC region seems to have no significant effect on lake water quality. Conversely, LUCC within ML and ZS region influenced algal area of corresponding lake divisions greatly, while the most sensitive regions were found in 3 km to 5 km, rather than the whole catchment. These results will be beneficial for the further understanding of the relationship between LUCC and lake water quality, and will provide a practical basis for the identification of critical regions for lake.

  9. Effects of sedimentation on soil physical and chemical properties and vegetation characteristics in sand dunes at the Southern Dongting Lake region, China

    PubMed Central

    Pan, Ying; Zhang, Hao; Li, Xu; Xie, Yonghong

    2016-01-01

    Sedimentation is recognized as a major factor determining the ecosystem processes of lake beaches; however, the underlying mechanisms, especially in freshwater sand dunes, have been insufficiently studied. To this end, nine belt transects from nine freshwater sand dunes, classified into low (<23.7 m), medium (25.4–26.0 m), and high-elevation groups (>28.1 m) based on their elevations in 1972, were sampled to investigate differences in sedimentation rate and soil and vegetation characteristics in Southern Dongting Lake, China. Sedimentation rate, soil sand content, and soil pH increased, whereas soil clay, fine silt, moisture (MC), organic matter (OM), total N, and total K content, in addition to the growth and biodiversity of sand dune plants generally decreased with decreasing belt transect elevation. Regression analyses revealed that the negative effects of sedimentation on the ecosystem functions of sand dunes could be attributed to higher fine sand content in deposited sediments and stronger inhibition of plant growth. These results are consistent with previous studies performed in coastal sand dunes, which highlights the importance of sedimentation in determining ecological processes. PMID:27808154

  10. Effects of sedimentation on soil physical and chemical properties and vegetation characteristics in sand dunes at the Southern Dongting Lake region, China

    NASA Astrophysics Data System (ADS)

    Pan, Ying; Zhang, Hao; Li, Xu; Xie, Yonghong

    2016-11-01

    Sedimentation is recognized as a major factor determining the ecosystem processes of lake beaches; however, the underlying mechanisms, especially in freshwater sand dunes, have been insufficiently studied. To this end, nine belt transects from nine freshwater sand dunes, classified into low (<23.7 m), medium (25.4–26.0 m), and high-elevation groups (>28.1 m) based on their elevations in 1972, were sampled to investigate differences in sedimentation rate and soil and vegetation characteristics in Southern Dongting Lake, China. Sedimentation rate, soil sand content, and soil pH increased, whereas soil clay, fine silt, moisture (MC), organic matter (OM), total N, and total K content, in addition to the growth and biodiversity of sand dune plants generally decreased with decreasing belt transect elevation. Regression analyses revealed that the negative effects of sedimentation on the ecosystem functions of sand dunes could be attributed to higher fine sand content in deposited sediments and stronger inhibition of plant growth. These results are consistent with previous studies performed in coastal sand dunes, which highlights the importance of sedimentation in determining ecological processes.

  11. Structure and spatial patterns of macrobenthic community in Tai Lake, a large shallow lake, China

    USGS Publications Warehouse

    Di Li,; Erickson, Richard A.; Song Tang,; Xuwen Li,; Niu, Zhichun; Xia Wang,; Hongling Liu,; Hongxia Yu,

    2016-01-01

    Tai Lake (Chinese: Taihu), the third-largest freshwater lake in China, suffers from harmful cyanobacteria blooms that are caused by economic development and population growth near the lake. Several studies have focused on phytoplankton in Tai Lake after a drinking water crisis in 2007; however, these studies primarily focused on microcystin bioaccumulation and toxicity to individual species without examining the effects of microcystin on macrobenthic community diversity. In this study, we conducted a survey of the lake to examine the effects of microcystine and other pollutants on marcobenthic community diversity. A totally of forty-nine species of macroinvertebrates were found in Tai Lake. Limnodrilus hoffmeisteri and Corbicula fluminea were the most abundant species. Cluster-analysis and one-way analysis of similarity (ANOSIM) identified three significantly different macrobenthic communities among the sample sites. More specifically, sites in the eastern bays, where aquatic macrophytes were abundant, had the highest diversity of macrobenthic communities, which were dominated by Bellamya aeruginosa, Bellamya purificata, L. hoffmeisteri, and Alocinma longicornis. Sites in Zhushan Bay contained relatively diverse communities, mainly composed of L. hoffmeisteri, C. fluminea, L. claparederanus, R. sinicus, and Cythura sp. Sites in the western region, Meiliang Bay and Wuli Bay had the lowest diversity, mainly composed ofL. hoffmeisteri, C. fluminea, Branchiura sowerbyi, and Rhyacodrilus sinicus. In addition, the relationships between macrobenthic metrics (Shannon–Wiener, Margalef, and Pielou) and environmental variables showed that community structure and spatial patterns of macrobenthos in Tai Lake were significantly influenced by chemical oxygen demand (CODCr), biochemical oxygen demand (BOD5), lead (Pb), and microcystin-LR (L for leucine and R for arginine). Our findings provide critical information that could help managers and policymakers

  12. Lake sediment records on climate change and human activities in the Xingyun Lake catchment, SW China.

    PubMed

    Zhang, Wenxiang; Ming, Qingzhong; Shi, Zhengtao; Chen, Guangjie; Niu, Jie; Lei, Guoliang; Chang, Fengqin; Zhang, Hucai

    2014-01-01

    Sediments from Xinyun Lake in central Yunnan, southwest China, provide a record of environmental history since the Holocene. With the application of multi-proxy indicators (total organic carbon (TOC), total nitrogen (TN), δ13C and δ15N isotopes, C/N ratio, grain size, magnetic susceptibility (MS) and CaCO3 content), as well as accelerator mass spectrometry (AMS) 14C datings, four major climatic stages during the Holocene have been identified in Xingyun's catchment. A marked increase in lacustrine palaeoproductivity occurred from 11.06 to 9.98 cal. ka BP, which likely resulted from an enhanced Asian southwest monsoon and warm-humid climate. Between 9.98 and 5.93 cal. ka BP, a gradually increased lake level might have reached the optimum water depth, causing a marked decline in coverage by aquatic plants and lake productivity of the lake. This was caused by strong Asian southwest monsoon, and coincided with the global Holocene Optimum. During the period of 5.60-1.35 cal. ka BP, it resulted in a warm and dry climate at this stage, which is comparable to the aridification of India during the mid- and late Holocene. The intensifying human activity and land-use in the lake catchment since the early Tang Dynasty (∼1.35 cal. ka BP) were associated with the ancient Dian culture within Xingyun's catchment. The extensive deforestation and development of agriculture in the lake catchment caused heavy soil loss. Our study clearly shows that long-term human activities and land-use change have strongly impacted the evolution of the lake environment and therefore modulated the sediment records of the regional climate in central Yunnan for more than one thousand years.

  13. Lake Sediment Records on Climate Change and Human Activities in the Xingyun Lake Catchment, SW China

    PubMed Central

    Zhang, Wenxiang; Ming, Qingzhong; Shi, Zhengtao; Chen, Guangjie; Niu, Jie; Lei, Guoliang; Chang, Fengqin; Zhang, Hucai

    2014-01-01

    Sediments from Xinyun Lake in central Yunnan, southwest China, provide a record of environmental history since the Holocene. With the application of multi-proxy indicators (total organic carbon (TOC), total nitrogen (TN), δ13C and δ15N isotopes, C/N ratio, grain size, magnetic susceptibility (MS) and CaCO3 content), as well as accelerator mass spectrometry (AMS) 14C datings, four major climatic stages during the Holocene have been identified in Xingyun′s catchment. A marked increase in lacustrine palaeoproductivity occurred from 11.06 to 9.98 cal. ka BP, which likely resulted from an enhanced Asian southwest monsoon and warm-humid climate. Between 9.98 and 5.93 cal. ka BP, a gradually increased lake level might have reached the optimum water depth, causing a marked decline in coverage by aquatic plants and lake productivity of the lake. This was caused by strong Asian southwest monsoon, and coincided with the global Holocene Optimum. During the period of 5.60–1.35 cal. ka BP, it resulted in a warm and dry climate at this stage, which is comparable to the aridification of India during the mid- and late Holocene. The intensifying human activity and land-use in the lake catchment since the early Tang Dynasty (∼1.35 cal. ka BP) were associated with the ancient Dian culture within Xingyun’s catchment. The extensive deforestation and development of agriculture in the lake catchment caused heavy soil loss. Our study clearly shows that long-term human activities and land-use change have strongly impacted the evolution of the lake environment and therefore modulated the sediment records of the regional climate in central Yunnan for more than one thousand years. PMID:25033404

  14. Using multiple environmental methods to estimate groundwater discharge into an arid lake (Dakebo Lake, Inner Mongolia, China)

    NASA Astrophysics Data System (ADS)

    Su, Xiaosi; Cui, Geng; Du, Shanghai; Yuan, Wenzhen; Wang, Huang

    2016-11-01

    It is important to have both a qualitative and quantitative understanding of the hydraulic exchange between groundwater and surface water to support the development of effective management plans for sustainable use of water resources. Groundwater is a major source of surface-water recharge and plays an important role in maintaining the integrity of ecosystems, especially within wetlands in semi-arid regions. The Ordos Desert Plateau of Inner Mongolia (China) is a vulnerable ecosystem that suffers from an extreme lack of water. The hydraulic exchange between groundwater and lake water in Dakebo Lake (the largest of hundreds of lakes on the Ordos Desert Plateau) was evaluated using multiple environmental methods. Continuous monitoring of the groundwater and lake-water levels indicated that the lake was recharged vertically by groundwater. Application of hydrodynamic and temperature tracing methods to the western side of the lake indicated that the rate of groundwater discharge to the lake was about 2 × 10-6 to 3 × 10-6 m/s in spring, summer, and autumn, but that there was no recharge in winter because the hypolentic zone (HZ) was frozen. Mixing ratios of groundwater and lake water in the HZ, estimated from the 18O and 2H ratios, showed that there were spatial variations in the hydrodynamic exchange between groundwater and lake water within the HZ.

  15. Regional Monitoring of Acidic Lakes and Streams

    EPA Pesticide Factsheets

    This asset provides data on the acid-base status of lakes and streams. Key chemical indicators measured include: sulfate, nitrate, ammonium, chloride, Acid Neutralizing Capacity (ANC), pH, base cations, dissolved organic carbon (DOC), total aluminum. TIME and LTM are part of EPA's Environmental Monitoring and Assessment Program (EMAP). Long-term monitoring of the acid-base status (pH, ANC, SO4, NO3, NH4, DOC, base cations, Al) in lakes and streams. Monitoring is conducted in acid sensitive regions of the Eastern U.S.

  16. Effect of a large and very shallow lake on local summer precipitation over the Lake Taihu basin in China

    NASA Astrophysics Data System (ADS)

    Gu, Hongping; Ma, Zhuguo; Li, Mingxing

    2016-08-01

    Lake Taihu is the third largest freshwater lake in China and is situated in the Middle and lower Yangtze River delta. It is characterized by its shallowness (~1.9 m), large area (~2338 km2), and high turbidity in recent years. The lake's effect on local summer precipitation is first studied in this paper through the use of an atmosphere-lake coupled model. By enlarging the light extinction coefficient, modifying the radiation scheme, and setting the roughness length to constants, the coupled model after adjustment realistically reproduces the thermal stratification and magnitude of diurnal variation over Lake Taihu, with mean biases of 0.7°C for lake surface temperature and 0.4°C for near-surface air temperature, respectively. Based on this calibrated coupled model, two high-resolution numerical simulations with and without the lake (lake grid cells replaced by cropland) were conducted to identify the lake effects. The results show that an overall effect of Lake Taihu on local summer precipitation is negative during daytime and positive during nighttime and the precipitation pattern may be modified to some extent. The lake effect varies between areas and with time of day and occurs primarily on the downwind shore. A composite analysis for a representative decreased precipitation region reveals that during daytime in the summer, the combination of decreased air temperature and latent heat flux, along with intensified divergence and downdraft, acts together to stabilize the lower atmosphere and suppress thermal convective activities, ultimately resulting in less precipitation over this region.

  17. Relationships between testate amoeba communities and water quality in Lake Donghu, a large alkaline lake in Wuhan, China

    NASA Astrophysics Data System (ADS)

    Qin, Yangmin; Fournier, Bertrand; Lara, Enrique; Gu, Yansheng; Wang, Hongmei; Cui, Yongde; Zhang, Xiaoke; Mitchell, Edward A. D.

    2013-06-01

    The middle Yangtze Reach is one of the most developed regions of China. As a result, most lakes in this area have suffered from eutrophication and serious environmental pollution during recent decades. The aquatic biodiversity in the lakes of the area is thus currently under significant threat from continuous human activities. Testate amoebae (TA) are benthic (rarely planktonic) microorganisms characterized by an agglutinated or autogenous shell. Owing to their high abundance, preservation potential in lacustrine sediments, and distinct response to environmental stress, they are increasingly used as indicators for monitoring water quality and reconstructing palaeoenvironmental changes. However this approach has not yet been developed in China. This study presents an initial assessment of benthic TA assemblages in eight lakes of Lake Donghu in the region of Wuhan, China. Testate amoeba community structure was most strongly correlated to water pH. In more alkaline conditions, communities were dominated by Centropyxis aculeata, Difflugia oblonga, Pontigulasia compressa, Pon. elisa and Lesquereusia modesta. These results are consistent with previous studies and show that TA could be useful for reconstructing past water pH fluctuations in China. To achieve this, the next step will be to expand the database and build transfer function models.

  18. Advantages of China Lake for laser power beaming

    NASA Astrophysics Data System (ADS)

    Bennett, Harold E.

    1995-04-01

    The site for the proposed National Advanced Optic Mission Initiative (NAOMI) facility will be in the mountains near China Lake, California. This location has 260 clear days per year (more than any other feasible site in the U.S.). In 1993 there were 5 completely overcast days all year. The area near the proposed site is unpopulated. The solar insolation in this general area is the greatest of any area in the United States. The NAOMI system will be installed at an altitude of 5600 feet. Astronomical seeing there is excellent. Even at a less favored site than that planned for NAOMI the average Fried seeing coefficient ro is 12 cm in the visible region and 20 cm values of ro (comparable to the best observatories) are commonly observed. The area is centrally located in and entirely surrounded by one of the largest restricted airspace/military operating airspace complexes in the United States, 12% of the entire airspace in California. Electrical power is available from either the nearly Coso Geothermal plant, second largest in the United States, or from the even closer cogeneration plant at Trona, California. Cooling water can be obtained from the nearby area or from the lake itself. Although a dry playa, the lake has a high brackish groundwater level. Most of the commercial satellites over the U.S. could be reached by a laser/telescope system located on government land at the Naval Air Weapons Station (NAWS) military reservation at China Lake. This telescope/laser system will be a prototype for five other systems planned for around the world. The complex will provide laser power beaming to all satellites and put the United States into the position of world leader in satellite technology and power beaming to space.

  19. Pyrosequencing analysis of bacterial communities in Lake Bosten, a large brackish inland lake in the arid northwest of China.

    PubMed

    Zhang, Lei; Gao, Guang; Tang, Xiangming; Shao, Keqiang; Gong, Yi

    2016-06-01

    The bacteria inhabiting brackish lake environments are poorly known, and there are few studies on the microbial diversity of these environments. Lake Bosten, a large brackish inland lake, is the largest lake in Xinjiang Province in northwestern China. Because sediments record past limnic changes, the analysis of sedimentary bacteria in Lake Bosten may help elucidate bacterial responses to environmental change. We employed 454 pyrosequencing to investigate the diversity and bacterial community composition in Lake Bosten. A total of 48 230 high-quality sequence reads with 16 314 operational taxonomic units were successfully obtained from the 4 selected samples, and they were numerically dominated by members of the Deltaproteobacteria (17.1%), Chloroflexi (16.1%), Betaproteobacteria (12.6%), Bacteroidetes (6.6%), and Firmicutes (5.7%) groups, accounting for more than 58.1% of the bacterial sequences. The sediment bacterial communities and diversity were consistently different along the 2 geographic environmental gradients: (i) freshwater-brackish water gradient and (ii) oligotrophic-mesotrophic habitat gradient. Deltaproteobacteria, Chloroflexi, and Betaproteobacteria were amplified throughout all of the sampling sites. More Bacteroidetes and Firmicutes were found near the Kaidu River estuary (site 14). Our investigation showed that Proteobacteria did not display any systematic change along the salinity gradient, and numerous 16S rRNA sequences could not be identified at the genus level. Our data will provide a better understanding of the diversity and distribution of bacteria in arid region brackish lakes.

  20. A 100 year sedimentary record of heavy metal pollution in a shallow eutrophic lake, Lake Chaohu, China.

    PubMed

    Zan, Fengyu; Huo, Shouliang; Xi, Beidou; Su, Jing; Li, Xiang; Zhang, Jingtian; Yeager, Kevin M

    2011-10-01

    This study has worked on the evaluation of the temporal and spatial evolution of heavy metal contamination in sediment taken from a shallow eutrophic lake, Lake Chaohu, China, over the last 100 years, and thereby used (137)Cs and (210)Pb dating, a PIRLA procedure, statistical analysis, geochemical normalization and a enrichment factor calculation (EF). Concentrations of 5174, 29 325, 10.7, 36.4, 20.4, 386.0, 21.1 and 38.4 mg kg(-1) for Ti, Fe, Co, Cr, Cu, Mn, Pb and Zn, respectively, are proposed as natural background values for the Lake Chaohu based on a PIRLA procedure. The contamination history from the last 100 years can be divided into two periods. Before the 1960s, heavy metal contamination did not occur and there was no spatial difference for heavy metal distribution. Since the 1960s, heavy metal enrichment and contamination has occurred, and the west half of the lake region showed a higher degree of contamination than the east half to various intensified anthropogenic activities. In the east half of the lake region, the anthropogenic source of heavy metals mainly originated from agricultural intensification, whereas in the west half of the lake it originated from city runoff and industry as well as agriculture. In all anthropogenic heavy metals, Co is only from industry.

  1. Eutrophication of lake waters in China: cost, causes, and control.

    PubMed

    Le, C; Zha, Y; Li, Y; Sun, D; Lu, H; Yin, B

    2010-04-01

    Lake water eutrophication has become one of the most important factors impeding sustainable economic development in China. Knowledge of the current status of lake water eutrophication and determination of its mechanism are prerequisites to devising a sound solution to the problem. Based on reviewing the literature, this paper elaborates on the evolutional process and current state of shallow inland lake water eutrophication in China. The mechanism of lake water eutrophication is explored from nutrient sources. In light of the identified mechanism strategies are proposed to control and tackle lake water eutrophication. This review reveals that water eutrophication in most lakes was initiated in the 1980s when the national economy underwent rapid development. At present, the problem of water eutrophication is still serious, with frequent occurrence of damaging algal blooms, which have disrupted the normal supply of drinking water in shore cities. Each destructive bloom caused a direct economic loss valued at billions of yuan. Nonpoint pollution sources, namely, waste discharge from agricultural fields and nutrients released from floor deposits, are identified as the two major sources of nitrogen and phosphorus. Therefore, all control and rehabilitation measures of lake water eutrophication should target these nutrient sources. Biological measures are recommended to rehabilitate eutrophied lake waters and restore the lake ecosystem in order to bring the problem under control.

  2. Eutrophication of Lake Waters in China: Cost, Causes, and Control

    NASA Astrophysics Data System (ADS)

    Le, C.; Zha, Y.; Li, Y.; Sun, D.; Lu, H.; Yin, B.

    2010-04-01

    Lake water eutrophication has become one of the most important factors impeding sustainable economic development in China. Knowledge of the current status of lake water eutrophicatoin and determination of its mechanism are prerequisites to devising a sound solution to the problem. Based on reviewing the literature, this paper elaborates on the evolutional process and current state of shallow inland lake water eutrophication in China. The mechanism of lake water eutrophication is explored from nutrient sources. In light of the identified mechanism strategies are proposed to control and tackle lake water eutrophication. This review reveals that water eutrophication in most lakes was initiated in the 1980s when the national economy underwent rapid development. At present, the problem of water eutrophication is still serious, with frequent occurrence of damaging algal blooms, which have disrupted the normal supply of drinking water in shore cities. Each destructive bloom caused a direct economic loss valued at billions of yuan. Nonpoint pollution sources, namely, waste discharge from agricultural fields and nutrients released from floor deposits, are identified as the two major sources of nitrogen and phosphorus. Therefore, all control and rehabilitation measures of lake water eutrophication should target these nutrient sources. Biological measures are recommended to rehabilitate eutrophied lake waters and restore the lake ecosystem in order to bring the problem under control.

  3. Influence of the African Great Lakes on the regional climate

    NASA Astrophysics Data System (ADS)

    Thiery, Wim; Davin, Edouard; Panitz, Hans-Jürgen; Demuzere, Matthias; Lhermitte, Stef; van Lipzig, Nicole

    2015-04-01

    Although the African Great Lakes are important regulators for the East-African climate, their influence on atmospheric dynamics and the regional hydrological cycle remains poorly understood. We aim to assess this impact by conducting a regional climate model simulation which resolves individual lakes and explicitly computes lake temperatures. The regional climate model COSMO-CLM, coupled to a state-of-the-art lake parameterization scheme and land surface model, is used to dynamically downscale the COSMO-CLM CORDEX-Africa evaluation simulation to 7 km grid spacing for the period 1999-2008. Evaluation of the model reveals good performance compared to both in-situ and satellite observations, especially for spatio-temporal variability of lake surface temperatures and precipitation. Model integrations indicate that the four major African Great Lakes almost double precipitation amounts over their surface relative to a simulation without lakes, but hardly exert any influence on precipitation beyond their shores. The largest lakes also cool their near-surface air, this time with pronounced downwind influence. The lake-induced cooling happens during daytime, when the lakes absorb incoming solar radiation and inhibit upward turbulent heat transport. At night, when this heat is released, the lakes warm the near-surface air. Furthermore, Lake Victoria has profound influence on atmospheric dynamics and stability as it induces cellular motion with over-lake convective inhibition during daytime, and the reversed pattern at night. Overall, this study shows the added value of resolving individual lakes and realistically representing lake surface temperatures for climate studies in this region. Thiery, W., Davin, E., Panitz, H.-J., Demuzere, M., Lhermitte, S., van Lipzig, N.P.M., The impact of the African Great Lakes on the regional climate, J. Climate (in review).

  4. The Great Lakes' regional climate regimes

    NASA Astrophysics Data System (ADS)

    Sugiyama, Noriyuki

    For the last couple of decades, the Great Lakes have undergone rapid surface warming. In particular, the magnitude of the summer surface-warming trends of the Great Lakes have been much greater than those of surrounding land (Austin and Colman, 2007). Among the Great Lakes, the deepest Lake Superior exhibited the strongest warming trend in its annual, as well as summer surface water temperature. We find that many aspects of this behavior can be explained in terms of the tendency of deep lakes to exhibit multiple regimes characterized, under the same seasonally varying forcing, by the warmer and colder seasonal cycles exhibiting different amounts of wintertime lake-ice cover and corresponding changes in the summertime lake-surface temperatures. In this thesis, we address the problem of the Great Lakes' warming using one-dimensional lake modeling to interpret diverse observations of the recent lake behavior. (Abstract shortened by ProQuest.).

  5. Satellite-Observed Algae Blooms in China's Lake Taihu

    NASA Astrophysics Data System (ADS)

    Wang, Menghua; Shi, Wei

    2008-05-01

    During the spring of 2007, a massive blue-green algae (Microcystis) bloom broke out in Lake Taihu, one of the largest inland lakes in China. This freshwater lake is located in the Yangtze River delta (Figure 1), one of the world's most urbanized and heavily populated areas. The massive bloom event became an environmental crisis that prompted officials to cut tap water supply to several million residents in nearby Wuxi city in China's Jiangsu province. The outbreak, which the Chinese government identified as a major natural disaster, forced unprepared residents to rush to buy bottled water for their normal usage. This article presents results from an analysis of that event that demonstrate an application of satellite-derived imagery for inland lake water quality monitoring, assessment, and management.

  6. Effects of lake trout refuges on lake whitefish and cisco in the Apostle Islands Region of Lake Superior

    USGS Publications Warehouse

    Zuccarino-Crowe , Chiara M.; Taylor, William W.; Hansen, Michael J.; Seider, Michael J.; Krueger, Charles C.

    2016-01-01

    Lake trout refuges in the Apostle Islands region of Lake Superior are analogous to the concept of marine protected areas. These refuges, established specifically for lake trout (Salvelinus namaycush) and closed to most forms of recreational and commercial fishing, were implicated as one of several management actions leading to successful rehabilitation of Lake Superior lake trout. To investigate the potential significance of Gull Island Shoal and Devils Island Shoal refuges for populations of not only lake trout but also other fish species, relative abundances of lake trout, lake whitefish (Coregonus clupeaformis), and cisco (Coregonus artedi) were compared between areas sampled inside versus outside of refuge boundaries. During 1982–2010, lake trout relative abundance was higher and increased faster inside the refuges, where lake trout fishing was prohibited, than outside the refuges. Over the same period, lake whitefish relative abundance increased faster inside than outside the refuges. Both evaluations provided clear evidence that refuges protected these species. In contrast, trends in relative abundance of cisco, a prey item of lake trout, did not differ significantly between areas inside and outside the refuges. This result did not suggest indirect or cascading refuge effects due to changes in predator levels. Overall, this study highlights the potential of species-specific refuges to benefit other fish species beyond those that were the refuges' original target. Improved understanding of refuge effects on multiple species of Great Lakes fishes can be valuable for developing rationales for refuge establishment and predicting associated fish community-level effects.

  7. Variation of phytoplankton functional groups modulated by hydraulic controls in Hongze Lake, China.

    PubMed

    Tian, Chang; Pei, Haiyan; Hu, Wenrong; Hao, Daping; Doblin, Martina A; Ren, Ying; Wei, Jielin; Feng, Yawei

    2015-11-01

    Hongze Lake is a large, shallow, polymictic, eutrophic lake in the eastern China. Phytoplankton functional groups in this lake were investigated from March 2011 to February 2013, and a comparison was made between the eastern, western, and northern regions. The lake shows strong fluctuations in water level caused by monsoon rains and regular hydraulic controls. By application of the phytoplankton functional group approach, this study aims to investigate the spatial and temporal dynamics and analyze their influencing factors. Altogether, 18 functional groups of phytoplankton were identified, encompassing 187 species. In order to seek the best variable describing the phytoplankton functional group distribution, 14 of the groups were analyzed in detail using redundancy analysis. Due to the turbid condition of the lake, the dominant functional groups were those tolerant of low light. The predominant functional groups in the annual succession were D (Cyclotella spp. and Synedra acus), T (Planctonema lauterbornii), P (Fragilaria crotonensis), X1 (Chlorella vulgaris and Chlorella pyrenoidosa), C (Cyclotella meneghiniana and Cyclotella ocellata), and Y (Cryptomonas erosa). An opposite relationship between water level and the biomass of predominant groups was observed in the present study. Water level fluctuations, caused by monsoonal climate and artificial drawdown, were significant factors influencing phytoplankton succession in Hongze Lake, since they alter the hydrological conditions and influence light and nutrient availability. The clearly demonstrated factors, which significantly influence phytoplankton dynamics in Hongze Lake, will help government manage the large shallow lakes with frequent water level fluctuations.

  8. Drastic change in China's lakes and reservoirs over the past decades

    PubMed Central

    Yang, Xiankun; Lu, Xixi

    2014-01-01

    Using remote sensing images, we provided the first complete picture of freshwater bodies in mainland China. We mapped 89,700 reservoirs, covering about 26,870 km2 and approximately 185,000 lakes with a surface area of about 82,232 km2. Despite relatively small surface area, the total estimated storage capacity of reservoirs (794 km3) is triple that of lakes (268 km3). Further analysis indicates that reservoir construction has made the river systems strongly regulated: only 6% of the assessed river basins are free-flowing; 20% of assessed river basins have enough cumulative reservoir capacity to store more than the entire annual river flow. Despite the existence of 2,721 lakes greater than 1 km2, we found that about 50 lakes greater than km2 have formed on the Tibetan Plateau resulting from climate change. More than 350 lakes of ≥1 km2 vanished in four other major lake regions. Although the disappearance of lakes happened in the context of global climate change, it principally reflects the severe anthropogenic impacts on natural lakes, such as, the excessive plundering of water resources on the Inner Mongolia-Xinjiang Plateau and serious destruction (land reclamation and urbanization) on the eastern plains. PMID:25116335

  9. The accumulation and potential ecological risk of heavy metals in microalgae from a eutrophic lake (Taihu Lake, China).

    PubMed

    Yuan, Hezhong; Liu, Enfeng; Shen, Ji

    2015-11-01

    This study aimed to evaluate the bioaccumulation and enrichment of heavy metals in dominant microalgae and assess the potential ecological risk to the microalgae located at the northern region of Taihu Lake, China, a shallow freshwater lake. The concentrations of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in water and microalgae (predominant cyanophyta) collected from the north of Taihu Lake were analyzed. Subsequently, enrichment factors (EF) for heavy metals in microalgae relative to water were calculated. The concentrations and EF values of heavy metals were significantly higher in water and microalgae from the northern region compared with other regions for all the metals except As and Hg. Among the metals, Pb and Cd possessed higher enrichment levels, approx. 200 and 400 for Pb and Cd, respectively. This suggested that Pb and Cd had stronger chemisorption on microalgae, even though present at lower concentrations. Moreover, Ni and Zn in microalgae from the north of the lake also exhibited risk to the ecosystem owing to their high concentrations. In general, the microalgae tended to enrich Pb, Cd, Ni, and Zn by biosorption and bioaccumulation and thus exert a risk to the ecosystem and human populations.

  10. Sample representativeness: A must for reliable regional lake condition estimates

    SciTech Connect

    Peterson, S.A.; Urquhart, N.S.; Welch, E.B.

    1999-05-15

    Reliable environmental resource estimates are essential to informed regional scale decisions regarding protection, restoration, and enhancement of natural resources. Reliable estimates depend on objective and representative sampling. Probability-based sampling meets these requirements and provides accuracy estimates. Non-probability-based sampling often is biased, thus less reliable, and potentially misleading. The authors compare results from a probability- and a non-probability-based Secchi transparency sampling of lakes in the northeastern geographic region of the United States and its three primary ecoregions. Results from these samplings are compared on the basis of sample representativeness relative to the regional lake population and subsequent reliability of lake condition estimates. Statistically derived sampling indicates the northeast lake population median lake size to be about 9.5 ({+-}2.3) ha and the Secchi disk transparency (SDT) to be about 2.4 ({+-}0.4) m. On the basis of judgment sampling estimates, the median SDT for lakes in the same area would be 4.2 m. However, only about 15% of the regional lake population based on statistically designed sampling estimates has a SDT {ge} 4.2 m. Estimate unreliability of this magnitude can have profound effects on lake management decisions. Thus, regional extrapolation of non-probability-based sampling results should be avoided.

  11. Eighteen Years of the Great Lakes Regional Counseling Psychology Conference: Revisiting the Need for Regional Conferences

    ERIC Educational Resources Information Center

    Delgado-Romero, Edward A.; Bowman, Sharon L.; Gerstein, Lawrence H.

    2006-01-01

    The Great Lakes Regional Conference on Counseling Psychology is the only conference to continuously fulfill the 1987 mandate issued by Division 17 for regional counseling conferences. The rationale for regional conferences is reviewed, and the 18-year history of the Great Lakes Regional Conference is examined. The authors conclude by noting the…

  12. Temporal and spatial changes of water quality and management strategies of Dianchi Lake in southwest China

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Zeng, W. H.; Wang, S. R.; Ni, Z. K.

    2014-04-01

    Temporal and spatial changes to the water quality of Dianchi Lake in southwest China were investigated using monthly monitoring data from 2005 to 2012. Dianchi Lake is divided into two parts, Caohai Lake and Waihai Lake, by a man-made dike. Caohai Lake lies at the north of Dianchi Lake, while Waihai Lake is the main water body of Dianchi Lake and accounts for 96.7% of the whole area of the lake. Based on the analysis of total phosphorus (TP), total nitrogen (TN), and chlorophyll a (Chl a) concentrations, it was determined that, in Caohai Lake, the annual concentrations of these variables ranged from 0.19-1.46 mg L-1, 6.11-16.79 mg L-1, 0.06-0.14 mg L-1, respectively. In addition, the annual concentrations of TP, TN and Chl a in Waihai Lake ranged between 0.13 and 0.20 mg L-1, 1.82 and 3.01 mg L-1, and 0.04 and 0.09 mg L-1, respectively. Cluster analysis (CA) classified the 10 monitoring sites into two clusters (cluster A and cluster B) based on similarities of water quality characteristics. Our data revealed that the current status of water quality within Caohai Lake was much worse than that of Waihai Lake. Water quality was seriously degraded during the economic boom near the period of the "Eleventh Five-Year Plan" (2005-2010), and gradually improved from 2010 to 2012 because of the "standard emission directive to industry". The main factors that influenced the spatial and temporal changes to water quality were natural factors including lake evolution and regional characteristic as well as human factors such as pollution load into the lake and management strategies that were already adopted. Some activities and regulations were implemented to enhance the lake environment by controlling wastewater emissions and establishing regulations to protect the lakes in the Yunnan Province. However, problems with institutional fragmentation (horizontal and vertical), simple treatment methods, low-intensity investment in pollution control, and lack of meaningful endogenous

  13. Effect of continuous application of inorganic nitrogen fertilizer on selenium concentration in vegetables grown in the Taihu Lake Region of China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Selenium is an essential trace element in humans and other animals. Selenium enters the food chain primarily through plants and consequently, the consumption of Se-containing plants is necessary for maintaining adequate Se nutrition levels in humans and animals in Se-sensitive regions of the world, ...

  14. Pirla 2 project: Regional assessment of lake acidification trends

    SciTech Connect

    Charles, D.F.; Smol, J.P.

    1990-01-01

    PIRLA II (Paleoecological Investigation of Recent Lake Acidification) is the first paleolimnological study designed to make statistically based regional population estimates of lake acidification. It is also the first project in which only tops and bottoms of cores are analyzed so that a large number of lakes can be studied. The PIRLA II project consists of several components that are designed to address specific questions and are integrally related to several other projects. PIRLA II builds on the foundation laid by PIRLA I; together they make up one of the largest paleolimnological projects in terms of number of lakes investigated (over 120 lakes analyzed stratigraphically). PIRLA has made and will continue to make important contributions to the understanding of lake acidification and to the development of the field of paleolimnology.

  15. Methane efflux from the pelagic regions of four lakes

    SciTech Connect

    Miller, L.G.; Oremland, R.S. )

    1988-09-01

    Methane emission to the atmosphere was studied in the deepest, central (pelagic) regions of one freshwater and three meromictic, alkaline saline lakes. The range of methane emissions was 0.004 to 2.916 mmol/sq m/hr (n=41). Outward flux was dominated by bubble ebullition only in the freshwater lake. Diffusive gas exchange was the sole mechanism of transfer in the meromictic lakes, and flux from these lakes was equivalent to or lower than that from the freshwater lake during its periods of ebullition. A comparison of measured flux with flux calculated using a model of gas exchange in Mono Lake suggested that floating chambers provide reasonable estimates of the magnitude of methane emissions from diffusion-dominated systems. 43 refs., 4 figs., 2 tabs.

  16. Temporal and spatial changes of water quality and management strategies of Dianchi Lake in southwest China

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Zeng, W. H.; Wang, S. R.; Ni, Z. K.

    2013-12-01

    Temporal and spatial changes to the water quality of Dianchi Lake in Southwest China were investigated using monthly monitoring data from 2005 to 2012. Based on the analysis of total phosphorus (TP), total nitrogen (TN), and chlorophyll a (Chl a) concentrations, it was determined that, in Caohai Lake, the annual concentrations of these variables ranged from 0.19-1.46, 6.11-16.79, 0.06-0.14 mg L-1, respectively. In addition, the annual concentrations of TP, TN and Chl a in Waihai Lake ranged between 0.13-0.20, 1.82-3.01, 0.04-0.09 mg L-1, respectively. Cluster Analysis (CA) classified the 10 monitoring sites into two groups (group A and group B) based on similarities of water quality characteristics. Our data revealed that the current status of water quality within Caohai Lake was much worse than that of Waihai Lake. Water quality was seriously degraded during the economic boom near the period of the "Eleventh Five-Year Plan" (2005-2010), and gradually improved from 2010 to 2012 because of the "standard emission directive to industry". The main factors that influenced the spatial and temporal changes to water quality were natural factors including lake evolution and regional characteristic as well as human factors such as pollution load into the lake and management strategies that were already adopted. Some activities and regulations were implemented to enhance the lake environment by controlling wastewater emissions and establishing regulations to protect the lakes in the Yunnan Province. However, problems with institutional fragmentation (horizontal and vertical), simple treatment methods, low-intensity investment in pollution control, and lack of meaningful endogenous pollution control strategies were still present in the lake management strategy. To solve these problems, suitable control measures are needed, especially considering the current old-age status of Dianchi Lake. The fundamental improvement of the water quality within Caohai Lake was dependent on the

  17. Regional climate model performance in the Lake Victoria basin

    NASA Astrophysics Data System (ADS)

    Williams, Karina; Chamberlain, Jill; Buontempo, Carlo; Bain, Caroline

    2015-03-01

    Lake Victoria, the second largest freshwater lake in the world, plays a crucial role in the hydrology of equatorial eastern Africa. Understanding how climate change may alter rainfall and evaporation patterns is thus of vital importance for the economic development and the livelihood of the region. Regional rainfall distribution appears, up to a large extent, to be controlled by local drivers which may be not well resolved in general circulation model simulations. We investigate the performance over the Lake Victoria basin of an ensemble of UK Met Office Hadley Centre regional climate model (HadRM3P) simulations at 50 km, driven by five members of the Hadley Centre global perturbed-physics ensemble (QUMP). This is part of the validation of an ensemble of simulations that has been used to assess the impacts of climate change over the continent over the period 1950-2099. We find that the regional climate model is able to simulate a lake/land breeze over Lake Victoria, which is a significant improvement over the driving global climate model and a vital step towards reproducing precipitation characteristics in the region. The local precipitation correlates well with large-scale processes in the Pacific Ocean and Indian Ocean, which is in agreement with observations. We find that the spatial pattern of precipitation in the region and the diurnal cycle of convection is well represented although the amount of rainfall over the lake appears to be overestimated in most seasons. Reducing the observational uncertainty in precipitation over the lake through future field campaigns would enable this model bias to be better quantified. We conclude that increasing the spatial resolution of the model significantly improves its ability to simulate the current climate of the Lake Victoria basin. We suggest that, despite the higher computational costs, the inclusion of a model which allows two-way interactions between the lake and its surroundings should be seriously considered for

  18. Lake breezes in the southern Great Lakes region and their influence during BAQS-Met 2007

    NASA Astrophysics Data System (ADS)

    Sills, D. M. L.; Brook, J. R.; Levy, I.; Makar, P. A.; Zhang, J.; Taylor, P. A.

    2011-08-01

    Meteorological observations from the BAQS-Met field experiment during the summer months of 2007 were integrated and manually analyzed in order to identify and characterize lake breezes in the southern Great Lakes region of North America, and assess their potential impact on air quality. Lake breezes occurred frequently, with one or more lake breezes identified on 90 % of study days. They affected all parts of the study region, including southwestern Ontario and nearby portions of southeast Lower Michigan and northern Ohio, with lake-breeze fronts occasionally penetrating from 100 km to over 200 km inland. Occurrence rates and penetration distances were found to be higher than previously reported in the literature. This comprehensive depiction of observed lake breezes allows an improved understanding of their influence on the transport, dispersion, and production of pollutants in this region. The observational analyses were compared with output from subsequent runs of a high-resolution numerical weather prediction model. The model accurately predicted lake breeze occurrence and type in a variety of synoptic wind regimes, but selected cases showed substantial differences in the detailed timing and location of lake-breeze fronts, and with the initiation of deep moist convection. Knowledge of such strengths and weaknesses aids in the interpretation of results from air quality models driven by this meteorological model.

  19. Hydroclimatological influences at multi-spatial scales on recently increased droughts in China's largest freshwater lake

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Wu, G.

    2014-05-01

    Lake droughts are the consequences of climatic, hydrologic and anthropogenic influences. It may produce substantial impacts on local water sources, inhabitants and economy, but few studies have determined the contributions from the individual influences, especially under the changing climate, which is of highly valuable for policymakers to make effective adaption. This study proposes to use a multi-scale hydroclimatic analysis for the determination, taking Poyang Lake as an example. It is the China's largest freshwater lake, which has been undergoing drastic hydrological alterations in recent decade. Our analysis demonstrates that in the recent decade the lake droughts worsened in terms of duration, frequency, magnitude and severity, and intensified in magnitude significantly. At the lake region, water deficiency severed as the hydroclimatic foundation for the worsening droughts. Overall contribution to the lake droughts included decreased inflow (45%), increased outflow (24%), reduced local precipitation (23%), and increased evapotranspiration (8%). At the basin scale, the decreased inflow was ascribed to reduced basin-scale precipitation (82%) and increased evapotranspiration (18%). The increased outflow was principally controlled by the weakened blocking effects of the Yangtze River, which serves as a boundary condition of Poyang Lake. Water impoundments of the Three Gorges Dam (TGD) established upstream should not be responsible for the increased drought occurrence, but they may have enhanced the drought magnitude with a limit contribution. The findings provide an example of intensified lake droughts, and offer an insightful view into lake droughts under the changing climate and anthropogenic influences. It should be valuable for improving our understanding and for promoting effective climate adaptation and water resources management practices.

  20. Establishment of a Riparian Buffer Strip for Alleviating Lake Eutrophication in Eastern China

    NASA Astrophysics Data System (ADS)

    Kennedy, M.; Naka, K.; Wu, Y.

    2014-12-01

    Riparian buffer strips are a growing conservation practice to control and mitigate non-point source pollution in Asia. China has seen rapid population growth and economic development in the last fifty years, coupled with a rapid increase in environmental pollution. Freshwater ecosystems have been particularly affected. Lake Tai, China's 3rd largest freshwater lake by volume, has seen a severe reduction in water quality since economic reforms began in the 1970s. Thus, significant interest for establishing riparian buffer strips in agricultural watersheds and freshwater systems within China is warranted. Eight 50 m x 20 m plots adjacent to a rice-phragmites farm were cleared within the Lake Tai basin region in Jiangsu Province, China. Seven plots were planted with either a Poplar hybrid, Cypress hybrid or a combination of both at varying densities, while the control and final plot allowed only for local vegetation to grow naturally. Soil, tree and groundwater samples were collected from all plots and analyzed for nitrogen and phosphorus concentrations. At this time in the study, results have been analyzed only for nitrogen concentrations using the ANOVA procedure. Results for both nitrogen and phosphorus concentrations are currently being analyzed.

  1. Microbial Diversity in Water and Sediment of Lake Chaka, an Athalassohaline Lake in Northwestern China

    PubMed Central

    Jiang, Hongchen; Dong, Hailiang; Zhang, Gengxin; Yu, Bingsong; Chapman, Leah R.; Fields, Matthew W.

    2006-01-01

    We employed culture-dependent and -independent techniques to study microbial diversity in Lake Chaka, a unique hypersaline lake (32.5% salinity) in northwest China. It is situated at 3,214 m above sea level in a dry climate. The average water depth is 2 to 3 cm. Halophilic isolates were obtained from the lake water, and halotolerant isolates were obtained from the shallow sediment. The isolates exhibited resistance to UV and gamma radiation. Microbial abundance in the sediments ranged from 108 cells/g at the water-sediment interface to 107 cells/g at a sediment depth of 42 cm. A major change in the bacterial community composition was observed across the interface. In the lake water, clone sequences affiliated with the Bacteroidetes were the most abundant, whereas in the sediments, sequences related to low G+C gram-positive bacteria were predominant. A similar change was also present in the archaeal community. While all archaeal clone sequences in the lake water belonged to the Halobacteriales, the majority of the sequences in the sediments were related to those previously obtained from methanogenic soils and sediments. The observed changes in the microbial community structure across the water-sediment interface were correlated with a decrease in salinity from the lake water (32.5%) to the sediments (approximately 4%). Across the interface, the redox state also changed from oxic to anoxic and may also have contributed to the observed shift in the microbial community. PMID:16751487

  2. Occurrence and distribution of microcystins in Lake Taihu, China.

    PubMed

    Sakai, Hiroshi; Hao, Aimin; Iseri, Yasushi; Wang, Song; Kuba, Takahiro; Zhang, Zhenjia; Katayama, Hiroyuki

    2013-01-01

    The occurrence and distribution of microcystins were investigated in Lake Taihu, the third largest lake in China. An extensive survey, larger and broader in scale than previous studies, was conducted in summer 2010. The highest microcystin concentration was found at southern part of Taihu, which was newly included in this survey. In northern coastal areas, total cellular concentrations of 20 to 44 μg/L were observed. In northern offshore waters, levels were up to 4.8 μg/L. Microcystin occurrence was highly correlated with chemical oxygen demand, turbidity, and chlorophyll-a. Extracellular/total cellular microcystin (E/T) ratios were calculated and compared to other water quality parameters. A higher correlation was found using E/T ratios than original microcystin values. These results show that algal blooms are having a severe impact on Lake Taihu, and further and extensive monitoring and research are required to suppress blooms effectively.

  3. Anomalous plutonium isotopic ratios in sediments of Lake Qinghai from the Qinghai-Tibetan Plateau, China.

    PubMed

    Wu, Fengchang; Zheng, Jian; Liao, Haiqing; Yamada, Masatoshi; Wan, Guojiang

    2011-11-01

    The vertical profiles of (239+240)Pu and (137)Cs activities and (240)Pu/(239)Pu isotopic ratios are determined for three sediment cores of Lake Qinghai from the Qinghai-Tibetan Plateau, China, and compared with those in sediments of another three lakes (Lakes Bosten, Sugan, and Shuangta), the only existing ones closest to Lop Nor area, China's nuclear weapons test site in the northwestern part of the country. The mean inventory of 47.7 ± 18.7 MBq km(-2) for (239+240)Pu activity in Lake Qinghai is comparable to the average value of global fallout expected at the same latitude, yet the mean inventory of 1112.0 ± 78.0 MBq km(-2) for (137)Cs is slightly lower than that of global fallout. Anomalously low (240)Pu/(239)Pu isotopic ratios (0.038-0.125) were found in the 3-6.5 cm deep sediment layers, indicating the trace Pu input from early nuclear weapons research activities at Atomic City in the lake's watershed during the 1950-60s. Model calculation indicated that the Pu input accounted for approximately 5-16% of the total Pu inventory. The observation of low (240)Pu/(239)Pu ratio in the deep sediment layer provided a new time marker for recent sediment dating in the lake and around the area. The results are of great significance to the further understanding of sources, records, and environmental impacts of global and regional nuclear activities in the environment and provide important chronological information for further studies on the water eutrophication process and climatic change, and reconstruction of pollution history of organic contaminants and heavy metals in the watershed of Lake Qinghai.

  4. Dynamics of the lakes in the middle and lower reaches of the Yangtze River basin, China, since late nineteenth century.

    PubMed

    Cui, Lijuan; Gao, Changjun; Zhao, Xinsheng; Ma, Qiongfang; Zhang, Manyin; Li, Wei; Song, Hongtao; Wang, Yifei; Li, Shengnan; Zhang, Yan

    2013-05-01

    The middle and lower reaches of the Yangtze River basin have the most representative and largest concentration of freshwater lakes in China. However, the size and number of these lakes have changed considerably over the past century due to the natural and anthropogenic impact. The lakes, larger than 10 km(2) in size, were chosen from relief maps and remotely sensed images in 1875, 1950, 1970, 1990, 2000, and 2008 to study the dynamics of lakes in the middle and lower reaches of the Yangtze River basin and to examine the causes and consequences of these changes. Results indicated that there was a dramatic reduction in lake areas, which decreased by 7,841.2 km(2) (42.64 %) during the study period (1875-2008), and the number of lakes in this region changed moderately. Meanwhile, a large number of lakes in the middle and lower reaches of the Yangtze River basin were directly converted into paddy fields, ponds, building lands, or other land-use types over the study period. Therefore, all kinds of lake reclamation should be identified as the major driving factors for the loss of lake in this region. Furthermore, flooding, soil erosion, and sedimentation were also the main factors which triggered lake changes in different periods. Some wetland conservation and restoration projects have been implemented since the 1970s, but they have not reversed the lake degradation. These findings were of great importance to managers involved in making policy for the conservation of lake ecosystems and the utilization of lake resources.

  5. Great Lakes nearshore-offshore: Distinct water quality regions

    EPA Science Inventory

    We compared water quality of nearshore regions in the Laurentian Great Lakes to water quality in offshore regions. Sample sites for the nearshore region were from the US EPA National Coastal Condition Assessment and based on a criteria or sample-frame of within the 30-m depth co...

  6. Forecasting Lake-Effect Precipitation in the Great Lakes Region Using NASA Enhanced-Satellite Data

    NASA Technical Reports Server (NTRS)

    Cipullo, Michelle; Molthan, Andrew; Shafer, Jackie; Case, Jonathan; Jedlovec, Gary

    2011-01-01

    Lake-effect precipitation is common in the Great Lakes region, particularly during the late fall and winter. The synoptic processes of lake-effect precipitation are well understood by operational forecasters, but individual forecast events still present a challenge. Locally run, high resolution models can assist the forecaster in identifying the onset and duration of precipitation, but model results are sensitive to initial conditions, particularly the assumed surface temperature of the Great Lakes. The NASA Short-term Prediction Research and Transition (SPoRT) Center has created a Great Lakes Surface Temperature (GLST) composite, which uses infrared estimates of water temperatures obtained from the MODIS instrument aboard the Aqua and Terra satellites, other coarser resolution infrared data when MODIS is not available, and ice cover maps produced by the NOAA Great Lakes Environmental Research Lab (GLERL). This product has been implemented into the Weather Research and Forecast (WRF) model Environmental Modeling System (WRF-EMS), used within forecast offices to run local, high resolution forecasts. The sensitivity of the model forecast to the GLST product was analyzed with a case study of the Lake Effect Storm Echinacea, which produced 10 to 12 inches of snowfall downwind of Lake Erie, and 8 to 18 inches downwind of Lake Ontario from 27-29 January 2010. This research compares a forecast using the default Great Lakes surface temperatures from the Real Time Global sea surface temperature (RTG SST), in the WRF-EMS model to the enhanced NASA SPoRT GLST product to study forecast impacts. Results from this case study show that the SPoRT GLST contained less ice cover over Lake Erie and generally cooler water temperatures over Lakes Erie and Ontario. Latent and sensible heat fluxes over Lake Ontario were decreased in the GLST product. The GLST product decreased the quantitative precipitation forecast (QPF), which can be correlated to the decrease in temperatures and heat

  7. Novel Virophages Discovered in a Freshwater Lake in China.

    PubMed

    Gong, Chaowen; Zhang, Weijia; Zhou, Xuewen; Wang, Hongming; Sun, Guowei; Xiao, Jinzhou; Pan, Yingjie; Yan, Shuling; Wang, Yongjie

    2016-01-01

    Virophages are small double-stranded DNA viruses that are parasites of giant DNA viruses that infect unicellular eukaryotes. Here we identify a novel group of virophages, named Dishui Lake virophages (DSLVs) that were discovered in Dishui Lake (DSL): an artificial freshwater lake in Shanghai, China. Based on PCR and metagenomic analysis, the complete genome of DSLV1 was found to be circular and 28,788 base pairs in length, with a G+C content 43.2%, and 28 predicted open reading frames (ORFs). Fifteen of the DSLV1 ORFs have sequence similarity to known virophages. Two DSLV1 ORFs exhibited sequence similarity to that of prasinoviruses (Phycodnaviridae) and chloroviruses (Phycodnaviridae), respectively, suggesting horizontal gene transfer occurred between these large algal DNA viruses and DSLV1. 46 other virophages-related contigs were also obtained, including six homologous major capsid protein (MCP) gene. Phylogenetic analysis of these MCPs showed that DSLVs are closely related to OLV (Organic Lake virophage) and YSLVs (Yellowstone Lake virophages), especially to YSLV3, except for YSLV7. These results indicate that freshwater ecotopes are the hotbed for discovering novel virophages as well as understanding their diversity and properties.

  8. Novel Virophages Discovered in a Freshwater Lake in China

    PubMed Central

    Gong, Chaowen; Zhang, Weijia; Zhou, Xuewen; Wang, Hongming; Sun, Guowei; Xiao, Jinzhou; Pan, Yingjie; Yan, Shuling; Wang, Yongjie

    2016-01-01

    Virophages are small double-stranded DNA viruses that are parasites of giant DNA viruses that infect unicellular eukaryotes. Here we identify a novel group of virophages, named Dishui Lake virophages (DSLVs) that were discovered in Dishui Lake (DSL): an artificial freshwater lake in Shanghai, China. Based on PCR and metagenomic analysis, the complete genome of DSLV1 was found to be circular and 28,788 base pairs in length, with a G+C content 43.2%, and 28 predicted open reading frames (ORFs). Fifteen of the DSLV1 ORFs have sequence similarity to known virophages. Two DSLV1 ORFs exhibited sequence similarity to that of prasinoviruses (Phycodnaviridae) and chloroviruses (Phycodnaviridae), respectively, suggesting horizontal gene transfer occurred between these large algal DNA viruses and DSLV1. 46 other virophages-related contigs were also obtained, including six homologous major capsid protein (MCP) gene. Phylogenetic analysis of these MCPs showed that DSLVs are closely related to OLV (Organic Lake virophage) and YSLVs (Yellowstone Lake virophages), especially to YSLV3, except for YSLV7. These results indicate that freshwater ecotopes are the hotbed for discovering novel virophages as well as understanding their diversity and properties. PMID:26834726

  9. Sources appointment and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in sediments of Erhai Lake, a low-latitude and high-altitude lake in southwest China.

    PubMed

    Hezhong, Yuan; Enlou, Zhang; Qi, Lin; Rong, Wang; Enfeng, Liu

    2016-03-01

    Sixteen polycyclic aromatic hydrocarbons (PAHs) were analyzed from the surficial sediments in Erhai Lake, a plateau lake in China. The results showed that except for acenaphthylene (Ace) Ace and Dibenz(a,h)anthracene (DBA), the central region contained individual PAHs at concentrations lower than those in other lake regions. Total concentration of the PAHs (ΣPAHs) in the sediments from Erhai Lake ranged from 32.42 to 558.53 mg/kg with a mean value of 256.70 mg/kg. The maximum value of ΣPAHs was observed in the north region of the lake and more than 10-fold higher than the minimum values. Moreover, high molecular weight (HMW) PAHs, especially 5-ring PAHs, accounted for higher ratios up to 76 % relative to other PAHs compound in almost all sampling sites. Molecular diagnostic ratios including anthtacene (Ant)/(Ant + phenanthrene (Phe)), fluoranthene (Flt)/(Flt + pyrene (Pyr)), benz(a)anthracene (BaA)/(BaA + chrysene (Chr)), and indeno(1,2,3-cd)pyrene (IPY)/(IPY + benz(g,h,i)perylene (BPE)) were recorded at all sampling sites and indicated that the origin of PAHs in Erhai Lake was predominately pyrolytic. Furthermore, principal component analysis with component dominating by HMW PAHs showed that combustion origins were the primary contamination sources of PAHs in the sediments of Erhai Lake. Finally, ecological risk assessment indicated that the sediments from Erhai Lake are exposed to potential low risk for ΣPAHs, and the ecological risk decreases in the order of northern region > southern region > central region.

  10. A drinking water crisis in Lake Taihu, China: linkage to climatic variability and lake management.

    PubMed

    Qin, Boqiang; Zhu, Guangwei; Gao, Guang; Zhang, Yunlin; Li, Wei; Paerl, Hans W; Carmichael, Wayne W

    2010-01-01

    In late May, 2007, a drinking water crisis took place in Wuxi, Jiangsu Province, China, following a massive bloom of the toxin producing cyanobacteria Microcystis spp. in Lake Taihu, China's third largest freshwater lake. Taihu was the city's sole water supply, leaving approximately two million people without drinking water for at least a week. This cyanobacterial bloom event began two months earlier than previously documented for Microcystis blooms in Taihu. This was attributed to an unusually warm spring. The prevailing wind direction during this period caused the bloom to accumulate at the shoreline near the intake of the water plant. Water was diverted from the nearby Yangtze River in an effort to flush the lake of the bloom. However, this management action was counterproductive, because it produced a current which transported the bloom into the intake, exacerbating the drinking water contamination problem. The severity of this microcystin toxin containing bloom and the ensuing drinking water crisis were attributable to excessive nutrient enrichment; however, a multi-annual warming trend extended the bloom period and amplified its severity, and this was made worse by unanticipated negative impacts of water management. Long-term management must therefore consider both the human and climatic factors controlling these blooms and their impacts on water supply in this and other large lakes threatened by accelerating eutrophication.

  11. Geochemical Responses to Anthropogenic and Natural Influences in Ebinur Lake Sediments of Arid Northwest China

    PubMed Central

    Wu, Jinglu; Abuduwaili, Jilili; Liu, Wen

    2016-01-01

    Geochemical concentrations were extracted for a short sediment core from Ebinur Lake, located in arid northwest China, and mathematical methods were used to demonstrate the complex pattern of the geochemical anomalies resulting from the temporal changes in natural and anthropogenic forces on the lake sediments. The first element assemblage (C1) (aluminum, potassium, iron, magnesium, beryllium, etc.) was predominantly terrigenous; among the assemblage, total phosphorus and titanium were generally consistent with aluminum except with regards to their surface sequences, which inferred the differences of source regions for terrigenous detrital material led to this change around ca. 2000AD. The second assemblage (C2) (calcium and strontium) was found to have a negative relationship with aluminum through a cluster analysis. The third assemblage (C3) included sodium and magnesium, which were influenced by the underwater lake environment and deposited in the Ebinur depression. The concentration ratio of C1/(C1+C2) was used as an indicator for denudation amount of detrital materials, which was supported by the values of magnetic susceptibility. The enrichment factors for heavy metals suggested that the influence of human activities on heavy-metal enrichment in Ebinur Lake region was not severe over the past century. Prior to the 1960s, geochemical indicators suggested a stable lacustrine environment with higher water levels. Beginning in the 1960s, high agricultural water demand resulted in rapid declines in lake water level, with subsequent increases of lake water salinity, as evidenced by enhanced sodium concentration in lake core sediments. During this period, anthropogenic activity also enhanced the intensity of weathering and the denudation of the Ebinur watershed. PMID:27176765

  12. Geography of Alaska Lake Districts: Identification, Description, and Analysis of Lake-Rich Regions of a Diverse and Dynamic State

    USGS Publications Warehouse

    Arp, Christopher D.; Jones, Benjamin M.

    2009-01-01

    Lakes are abundant landforms and important ecosystems in Alaska, but are unevenly distributed on the landscape with expansive lake-poor regions and several lake-rich regions. Such lake-rich areas are termed lake districts and have landscape characteristics that can be considered distinctive in similar respects to mountain ranges. In this report, we explore the nature of lake-rich areas by quantitatively identifying Alaska's lake districts, describing and comparing their physical characteristics, and analyzing how Alaska lake districts are naturally organized and correspond to climatic and geophysical characteristics, as well as studied and managed by people. We use a digital dataset (National Hydrography Dataset) of lakes greater than 1 hectare, which includes 409,040 individual lakes and represents 3.3 percent of the land-surface area of Alaska. The selection criteria we used to identify lake districts were (1) a lake area (termed limnetic ratio, in percent) greater than the mean for the State, and (2) a lake density (number of lakes per unit area) greater than the mean for the State using a pixel size scaled to the area of interest and number of lakes in the census. Pixels meeting these criteria were grouped and delineated and all groups greater than 1,000 square kilometers were identified as Alaska's lake districts. These lake districts were described according to lake size-frequency metrics, elevation distributions, geology, climate, and ecoregions to better understand their similarities and differences. We also looked at where lake research and relevant ecological monitoring has occurred in Alaska relative to lake districts and how lake district lands and waters are currently managed. We identified and delineated 20 lake districts in Alaska representing 16 percent of the State, but including 65 percent of lakes and 75 percent of lake area. The largest lake districts identified are the Yukon-Kuskokwim Delta, Arctic Coastal Plain, and Iliamna lake districts with

  13. Monitoring the Changes of Lakes in the Source Region of Three Rivers with Remote Sensing Data from 1976 TO 2009

    NASA Astrophysics Data System (ADS)

    Chengfeng, L.; Yuan, W.; Haoyan, J.; Zhengjun, L.

    2013-07-01

    As the birthplace of Yangtze River, the Yellow River and Lancang Rive, Source Region of Three Rivers (SRTR) is an important resource for fresh water supplement in China. SRTR also has very obvious ecological function which forms ecological security barrier for China's Qinghai-Tibet plateau. The inland lakes here play an important role for the water cycle in the plateau. The monitoring results were extracted with TM data from 1976 to 2009. The results show that from 1976 to 2009 the lakes' area in SRTR dropped first and then expanded with 2000 as sector. The lakes area was 6778 km2 in 2009, about 1.90% of the whole region, and increased than 1976 by 133.15 km2. Most of the large lakes above 80 km2 have the same change trend. The expanded lakes increased in number gradually, while the changes in the amplitude and time characteristics were different. From 1976 to 2000, the number of new lakes increased while died lakes dropped; and from 2000 to 2009 it is just on the contrary. In the study the index of lake change trend (ILCT) was adopted to contrast lake atrophy condition. With ILCT 24.55 there is an expansion trend for the lakes in SRTR during the last 35 years. The lakes with ILCT's absolute value greater than 1 were those merged with or disconnected from surrounding smaller lakes. Here the precipitation and snow melt are main supplies for the lakes. The change of lakes' area has well correlated with precipitation, and weak correlated with temperature from 1976 to 2009. But from 2000 to 2009, there has a strong correlation with precipitation, temperature. All these show from the side that the precipitation and snow melt are important factors to influence the lakes' change. The lakes have the coordination function for the good ecological environment in the region. The conclusions from the study can provide references in response to climate change research and rational utilization of water resources in SRTR.

  14. Winter and Summer Views of the Salt Lake Region

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Magnificent views of the region surrounding Salt Lake City, Utah are captured in these winter and summer images from the Multi-angle Imaging SpectroRadiometer's vertical-viewing (nadir) camera. Salt Lake City, situated near the southeastern shore of the Great Salt Lake, is host to the 2002 Winter Olympic Games, which open Friday, February 8. Venues for five of the scheduled events are at city (indoor) locations, and five in mountain (outdoor) facilities. All ten can be found within the area contained in these images. Some of the outdoor events take place at Ogden, situated north of Salt Lake City and at Park City, located to the east. Salt Lake City is surrounded by mountains including the Wasatch Range to the east, and the temperature difference between the Great Salt Lake and the overlying atmosphere enhances the moisture content of winter storms. These factors, in combination with natural cloud seeding by salt crystals from the lake, are believed to result in greater snowfall in neighboring areas compared to more distant locales. In addition to the obvious difference in snow cover between the winter and summer views, water color changes in parts of the Great Salt Lake are apparent in these images. The distinctly different coloration between the northern and southern arms of the Great Salt Lake is the result of a rock-filled causeway built in 1953 to support a permanent railroad. The causeway has resulted in decreased circulation between the two arms and higher salinity on the northern side. The southern part of the lake includes the large Antelope Island, and at full resolution a bridge connecting it to the mainland can be discerned. These images are natural color views acquired on February 8, 2001 and June 16, 2001, respectively. Each image represents an area of about 220 kilometers x 285 kilometers. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team.

  15. Influence of the Laurentian Great Lakes on Regional Climate

    NASA Astrophysics Data System (ADS)

    Notaro, M.; Holman, K.; Zarrin, A.; Fluck, E.; Vavrus, S. J.; Bennington, V.

    2012-12-01

    The influence of the Laurentian Great Lakes on climate is assessed by comparing two decade-long simulations, with the lakes either included or excluded, using the Abdus Salam International Centre for Theoretical Physics Regional Climate Model Version 4. The Great Lakes dampen the variability in near-surface air temperature across the surrounding region, while reducing the amplitude of the diurnal cycle and annual cycle of air temperature. The impacts of the Great Lakes on the regional surface energy budget include an increase (decrease) in turbulent fluxes during the cold (warm) season and an increase in surface downward shortwave radiation flux during summer due to diminished atmospheric moisture and convective cloud amount. Changes in the hydrologic budget due to the presence of the Great Lakes include increases in evaporation and precipitation during October-March and decreases during May-August, along with springtime reductions in snowmelt-related runoff. Circulation responses consist of a regionwide decrease in sea-level pressure in autumn-winter and an increase in summer, with enhanced ascent and descent in the two seasons, respectively. The most pronounced simulated impact of the Great Lakes on synoptic systems traversing the basin is a weakening of cold-season anticyclones.

  16. Lake breezes in the southern Great Lakes region and their influence during BAQS-Met 2007

    NASA Astrophysics Data System (ADS)

    Sills, D. M. L.; Brook, J. R.; Levy, I.; Makar, P. A.; Zhang, J.; Taylor, P. A.

    2011-02-01

    Mesoscale observations from the BAQS-Met field experiment during the summer of 2007 were integrated and manually analyzed in order to identify and characterize lake breezes in the southern Great Lakes region of North America, and assess their potential impact on air quality. Lake breezes were found to occur on 90% of study days, often occurring in conditions previously thought to impede their development. They affected all parts of the study region, including southwestern Ontario and nearby portions of southeast Michigan and northern Ohio, occasionally penetrating inland from 100 km to over 200 km. Occurrence rates and penetration distances were found to be higher than previously reported in the literature. This more accurate depiction of observed lake breezes allows a better understanding of their influence on the production and transport of pollutants in this region. The observational analyses were compared with output from subsequent runs of a high-resolution numerical weather prediction model. The model accurately predicted lake breeze occurrence in a variety of synoptic wind regimes, but selected cases showed substantial differences in the detailed timing and location of lake-breeze fronts, and with the initiation of deep moist convection. Knowledge of such strengths and weaknesses will assist with interpretation of results from air quality modelling driven by this meteorological model.

  17. The Effect of Lake Temperatures and Emissions on Ozone Exposure in the Western Great Lakes Region

    SciTech Connect

    Fast, Jerome D. ); Heilman, Warren E.

    2003-09-01

    A meteorological-chemical model with a 12-km horizontal grid spacing was used to simulate the evolution of ozone over the western Great Lakes region during a 30-day period in the summer of 1999. High ozone production rates were produced over the surface of the lakes as a result of stable atmospheric conditions that trapped ozone precursors within a shallow layer during the day. Simulations with lake temperatures derived from either satellite measurements or climatological values produced ozone mixing ratios over the lakes and around the lake shores that differed by as much as 50 ppb while differences over land were usually 10 ppb or less. Through another series of sensitivity studies that varied ozone precursor emissions, it was shown that a reduction of 50% NOx or VOC would lower the 60 ppb ozone exposure by up to 50 h per month in the remote forest regions over the northern Great Lakes. The implications of these results on future climate change and air quality in the region is discussed.

  18. Spatiotemporal variations of temperature and precipitation extremes in the Poyang Lake basin, China

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Xiao, Mingzhong; Singh, Vijay P.; Wang, Yeqiao

    2016-05-01

    Daily temperature and precipitation data from 15 rain gauges covering a period of 1957-2011 were analyzed using the Mann-Kendall trend test with the aim to investigate changing characteristics of weather extremes in the Poyang Lake basin, the largest freshwater lake in China. Also, the connection between El Niño Southern Oscillation (ENSO) and precipitation extremes is analyzed and possible causes for the connection are briefly discussed. Results indicate that (1) warming, characterized by a decreasing trend in frost days and a significant decrease of temperature extremes defined by lower temperature, in the Poyang Lake basin is observed. Temperature extremes, defined by higher temperature indices such as hot days, exhibit moderate changes with no significant trends. Moreover, warming occurs mainly in the northern part of the Poyang Lake basin; (2) precipitation changes are intensifying as reflected by increasing precipitation extremes. However, these changes are different from 1 month to another and the intensification is found mainly in winter and/or summer months; (3) the influence of ENSO on precipitation changes in the Poyang Lake basin is evident with a time lag of longer than 3 months. This should be due to the fact that higher sea surface temperature tends to trigger the occurrence of convective precipitation regimes. Results of this study are important for modeling the occurrence of precipitation extremes in a changing climate and regional climatic responses to global climate changes.

  19. 30+ year evolution of Cu in the surface sediment of Lake Poyang, China.

    PubMed

    Wang, Hua; Zhao, Yijun; Liang, Dongfang; Deng, Yanqing; Pang, Yong

    2017-02-01

    Poyang Lake, the largest freshwater lake in China, is increasingly experiencing Cu crises. Combining field data, laboratory experiments, and long-term simulations, we retrieved 30 + year evolution of Cu in surface sediments (SCu). SCu evolution between 1983 and 2015 may be separated into two distinguishable periods. During the first period (1983-2003), SCu underwent a continuous increase at a mean rate of 1.80 mg/kg/yr; however, since 2003 it displayed a stepwise reduction tendency. The average SCu concentration of the entire lake in 2015 fell to 54.26 mg/kg, which is approximately 30.01% lower than that in 2003. The operation of Three Gorges Dam (TGD) markedly altered the river-lake relationship, pulled more deposited Cu along with sediment out toward the Yangtze River, and made the regions of high SCu emanate from the southeastern lake extend northwestward between 2003 and 2015. SCu in the reserves showed significant inter-annual variations, with the exception of the Jiangxi Whitebait Spawning Reserve (JWSR), where SCu generally has not been significantly impacted and has displayed no departure from the 30 + year mean of 30.57 mg/kg. The National Germplasm Reserve (NGR) and Nanjishan National Nature Reserve (NNNR) were detected with the highest SCu, with the peak concentrations, respectively, of 123.15 mg/kg and 103.1 mg/kg.

  20. Evaluation of water quality and management of Hongze Lake and Gaoyou Lake along the Grand Canal in Eastern China.

    PubMed

    Li, Shuheng; Guo, Wei; Mitchell, Bruce

    2011-05-01

    Hongze Lake and Gaoyou Lake are the source of water for the Grand Canal and the eastern route of the South-to-North Water Transfer (SNWT) project. With the accelerating pace of construction of the SNWT and the initiative to achieve "World Heritage " status for the canal, the water quality and management of the lakes have gained attention in China. Based on analysis of water samples, monitoring data, and the content of heavy metal elements in surface sediments, the water quality of Gaoyou Lake and Hongze Lake have been examined. According to the analysis of the water samples taken in 2003, the content of the heavy metals met the water demands for Hongze Lake and Gaoyou Lake. However, monitoring data of 2004 indicate that the water quality of Hongze Lake and Gaoyou Lake both were worse than grade III which cannot meet the required standard. The heavy metal elements of sediment samples also were above the acceptable environmental standard values. Some projects were launched to promote the lake environment by controlling wastewater emissions, standardizing the types of boats and introducing regulations to protect the lakes. However, problems of vertical and horizontal fragmentation and insufficient public participation in the current management system still exist in the area. Considering the problems confronting the lakes, Integrated Water Resource Management is discussed as an effective approach to overcome the problems.

  1. From eutrophic lake to river: phytoplankton composition changes in river-lake system (Tanglangchuan River, China)

    NASA Astrophysics Data System (ADS)

    Yu, Qian; Chen, Yongcan; Liu, Zhaowei; Zhu, Dejun; van de Giesen, Nick

    2014-05-01

    Due to the fact that the Dianchi Lake is a hypereutrophic lake, we assume it is a potential source of cyanobacteria seed contributing to harmful algal blooms in the upper reach of the Tanglangchuan River (China). However, cyanobacteria, unlikely to survive in the short-retention-time river, are possibly replaced by other fast-growing algae along the river. To determine longitudinal changes of phytoplankton structures from Dianchi Lake to downstream Tanglangchuan River, samplings were carried out in June and September 2013 at 7 different stations. Among these stations, two of them are located in the mouth of Dianchi Lake (D1~D2) while the remaining five are along the main stream of the Tanglangchuan River (T1~T5). Then phytoplankton species were defined. We found that in June cyanobacteria dominated with more than 95% of the total cells in D1 and D2. The cyanobacteria sustained a long distance from T1 to T4 with a clear dominance of the total cells from 85.6% to 90.4%. However, in the last station (T5) which is located about 100km downstream the mouth of the Dianchi Lake, chlorophytes and bacillariophytes took the place of cyanobacteria and dominated (56.3% of the cells were chlorophytes and 27.1% were bacillariophytes). In autumn, the cyanobacteria dominated from D1 to T5 but the percentage and biomass of the cyanobacteria decreased along the river. The dominance of the cyanobacteria in the upper reach of the river indicates that the Dianchi Lake provides the cyanobacteria seed to the downstream river. Additionally, the transition of the algae dominance in the lower reach suggests that longitudinal changes in phytoplankton composition do exist. In view of the high concentration of total nitrogen and total phosphorus, changes of flow velocity and residence time should be key factors causing spatial succession.

  2. Reaching Regional and Local Learners via a Great Lakes MOOC

    NASA Astrophysics Data System (ADS)

    Mooney, M. E.; Ackerman, S. A.

    2015-12-01

    The Cooperative Institute of Meteorological Satellite Studies (CIMSS) took a regional approach to climate change education in a 4-week MOOC (Massive Open On-line Course) on the Changing Weather and Climate in the Great Lakes Region launched in February 2015. Featuring a different season each week, this Great Lakes MOOC includes lectures about seasonal weather conditions, observed changes, and societal impacts of regional climate change, as well as actions with co-benefits to slow future climate change. To better connect with learners, CIMSS facilitated 21 discussion groups at public libraries around Wisconsin each week. Participants discussed climate change impacts in their communities as well as strategies to mitigate climate change. Not surprisingly, initial survey results show library participants were more committed, engaged, climate literate, and community minded. This session will share lessons learned and survey results from the Great Lakes MOOC which remains open and accessible on Coursera through February 2016 at https://www.coursera.org/course/greatlakesclimate.

  3. The influence of natural and human factors in the shrinking of the Ebinur Lake, Xinjiang, China, during the 1972-2013 period.

    PubMed

    Zhang, Fei; Tiyip, Tashpolat; Johnson, Verner Carl; Kung, Hsiang-te; Ding, Jian-li; Sun, Qian; Zhou, Mei; Kelimu, Ardak; Nurmuhammat, Ilyas; Chan, Ngai Weng

    2015-01-01

    The Ebinur Lake is a closed inland lake located within the arid region of the Xinjiang Autonomous Region in the northwestern part of China, near the Kazakhstan border. The shrinkage of the lake area is believed to be caused by ecological environmental deterioration and has become an important restraining factor for the social development of the local population. Of all the lakes in the Xinjiang Autonomous Region, the Ebinur Lake is the most severely impacted water body. The lake has undergone change in size naturally for over thousands of years due to natural causes. However, the authors observed the dramatic changes in the freshwater resources of this region from the aerial images from 1972 to 2013. Thus, this paper traces and analyzes the change in the Ebinur Lake surface area in the past 41 years. A set of six satellite images acquired between 1972 and 2013 was employed to map the change in the surface area of the Ebinur Lake using the water index approach. The authors applied the traditional normalized difference water index (NDWI) and the modified normalized difference water index (MNDWI) to quantify the change in the water body area of the Ebinur Lake during the study period. The results indicate that the lake area has experienced a dramatic decrease of 31.4% from 1972 to 2013. The paper also examines the natural processes and human activities that may have contributed to the decrease in the lake area. The results show that the decrease in total lake area appears to coincide with periods of rapid land reclamation in the study area. Moreover, the uncontrolled land reclamation activities, such as irrigation, can increase the sedimentation in the Ebinur Lake thereby reducing the lake size. Reduction of the lake area has a negative ecological impact on the environment and on human life and property. The lake area is the most important factor to ensure the environment of the watershed and the key index to measure the environment balance.

  4. Effect of hydrological variability on diatom distribution in Poyang Lake, China

    NASA Astrophysics Data System (ADS)

    Qian, Kuimei; Liu, Xia; Chen, Yuwei

    2017-01-01

    Poyang Lake is the largest freshwater lake in China, and it has a seasonal flooding cycle that significantly changes the water level every year. The aim of this paper was to explain how these hydrological changes influence diatom populations in Poyang Lake. The yearly hydrological cycle can be divided into 4 phases: low water-level phase, increasing water-level phase, high water-level phase and decreasing water-level phase. Variations in the abundance of planktonic diatoms were studied using quarterly monitoring data collected from January 2009 to October 2013. Generally, diatoms were dominant in Poyang Lake and accounted for more than 50% of the total phytoplankton biomass except in July 2009 (26%) and January 2012 (35%). Aulacoseira granulata and Surirella robusta were the predominant species in all four phases, and they accounted for 25.02% to 56.89% and 5.07% to 14.78% of the total phytoplankton biomass, respectively. A redundancy analysis (RDA) showed that changes in physico-chemical parameter were related to the water level, and changes in diatom biomass were related to nitrite levels and pH. These results indicate that changes in environmental parameters related to both seasonal variations and water-level fluctuations caused variations in diatom biomass and community composition in Poyang Lake. Furthermore, extreme hydrological events can have different influences on the diatom community composition in the main channel and lentic regions. This research provides data on the diatom variations in Poyang Lake and will be useful for establishing biological indicators of environmental change and protecting Poyang Lake in the future.

  5. Regionalization of precipitation characteristics in Iran's Lake Urmia basin

    NASA Astrophysics Data System (ADS)

    Fazel, Nasim; Berndtsson, Ronny; Uvo, Cintia Bertacchi; Madani, Kaveh; Kløve, Bjørn

    2017-03-01

    Lake Urmia in northwest Iran, once one of the largest hypersaline lakes in the world, has shrunk by almost 90% in area and 80% in volume during the last four decades. To improve the understanding of regional differences in water availability throughout the region and to refine the existing information on precipitation variability, this study investigated the spatial pattern of precipitation for the Lake Urmia basin. Daily rainfall time series from 122 precipitation stations with different record lengths were used to extract 15 statistical descriptors comprising 25th percentile, 75th percentile, and coefficient of variation for annual and seasonal total precipitation. Principal component analysis in association with cluster analysis identified three main homogeneous precipitation groups in the lake basin. The first sub-region (group 1) includes stations located in the center and southeast; the second sub-region (group 2) covers mostly northern and northeastern part of the basin, and the third sub-region (group 3) covers the western and southern edges of the basin. Results of principal component (PC) and clustering analyses showed that seasonal precipitation variation is the most important feature controlling the spatial pattern of precipitation in the lake basin. The 25th and 75th percentiles of winter and autumn are the most important variables controlling the spatial pattern of the first rotated principal component explaining about 32% of the total variance. Summer and spring precipitation variations are the most important variables in the second and third rotated principal components, respectively. Seasonal variation in precipitation amount and seasonality are explained by topography and influenced by the lake and westerly winds that are related to the strength of the North Atlantic Oscillation. Despite using incomplete time series with different lengths, the identified sub-regions are physically meaningful.

  6. A Drinking Water Crisis in Lake Taihu, China: Linkage to Climatic Variability and Lake Management

    NASA Astrophysics Data System (ADS)

    Qin, Boqiang; Zhu, Guangwei; Gao, Guang; Zhang, Yunlin; Li, Wei; Paerl, Hans W.; Carmichael, Wayne W.

    2010-01-01

    In late May, 2007, a drinking water crisis took place in Wuxi, Jiangsu Province, China, following a massive bloom of the toxin producing cyanobacteria Microcystis spp. in Lake Taihu, China’s third largest freshwater lake. Taihu was the city’s sole water supply, leaving approximately two million people without drinking water for at least a week. This cyanobacterial bloom event began two months earlier than previously documented for Microcystis blooms in Taihu. This was attributed to an unusually warm spring. The prevailing wind direction during this period caused the bloom to accumulate at the shoreline near the intake of the water plant. Water was diverted from the nearby Yangtze River in an effort to flush the lake of the bloom. However, this management action was counterproductive, because it produced a current which transported the bloom into the intake, exacerbating the drinking water contamination problem. The severity of this microcystin toxin containing bloom and the ensuing drinking water crisis were attributable to excessive nutrient enrichment; however, a multi-annual warming trend extended the bloom period and amplified its severity, and this was made worse by unanticipated negative impacts of water management. Long-term management must therefore consider both the human and climatic factors controlling these blooms and their impacts on water supply in this and other large lakes threatened by accelerating eutrophication.

  7. Geospatial analysis of lake and landscape interactions within the Toolik Lake region, North Slope of Alaska

    NASA Astrophysics Data System (ADS)

    Pathak, Prasad A.

    The Arctic region of Alaska is experiencing severe impacts of climate change. The Arctic lakes ecosystems are bound to undergo alterations in its trophic structure and other chemical properties. However, landscape factors controlling the lake influxes were not studied till date. This research has examined the currently existing lake landscape interactions using Remote Sensing and GIS technology. The statistical modeling was carried out using Regression and CART methods. Remote sensing data was applied to derive the required landscape indices. Remote sensing in the Arctic Alaska faces many challenges including persistent cloud cover, low sun angle and limited snow free period. Tundra vegetation types are interspersed and intricate to classify unlike managed forest stands. Therefore, historical studies have remained underachieved with respect thematic accuracies. However, looking at vegetation communities at watershed level and the implementation of expert classification system achieved the accuracies up to 90%. The research has highlighted the probable role of interactions between vegetation root zones, nutrient availability within active zone, as well as importance of permafrost thawing. Multiple regression analyses and Classification Trees were developed to understand relationships between landscape factors with various chemical parameters as well as chlorophyll readings. Spatial properties of Shrubs and Riparian complexes such as complexity of individual patches at watershed level and within proximity of water channels were influential on Chlorophyll production of lakes. Till-age had significant impact on Total Nitrogen contents. Moreover, relatively young tills exhibited significantly positive correlation with concentration of various ions and conductivity of lakes. Similarly, density of patches of Heath complexes was found to be important with respect to Total Phosphorus contents in lakes. All the regression models developed in this study were significant at 95

  8. Global fallout Pu recorded in lacustrine sediments in Lake Hongfeng, SW China.

    PubMed

    Zheng, Jian; Wu, Fengchang; Yamada, Masatoshi; Liao, Haiqing; Liu, Congqiang; Wan, Guojiang

    2008-03-01

    Studies on the distribution and isotope compositions of fallout Pu are important for source characterization of possible future non-fallout Pu contamination in aquatic environments, and useful for dating of recent sediments to understand the pollution history of environmental contaminants. We present the historical record of atmospheric Pu fallout reconstructed from a sediment core from Lake Hongfeng, China. The Pu activity profile was in agreement with the 137Cs profile. Inventories were 50.7 Bq m(-2) for 239+240Pu and 1586 Bq m(-2) for 137Cs. The average 240Pu/239Pu atom ratio was 0.185+/-0.009, indicating that Pu originated from global stratospheric fallout rather than from direct tropospheric or close-in fallout from the Chinese nuclear testing conducted in the 1970s. Our data suggested that Lake Hongfeng would be an ideal setting for monitoring atmospheric fallout and environmental changes in this region.

  9. [Ecological compensation standard in Dongting Lake region of returning cropland to lake based on emergy analysis].

    PubMed

    Mao, De-Hua; Hu, Guang-Wei; Liu, Hui-Jie; Li, Zheng-Zui; Li, Zhi-Long; Tan, Zi-Fang

    2014-02-01

    The annual emergy and currency value of the main ecological service value of returning cropland to lake in Dongting Lake region from 1999 to 2010 was calculated based on emergy analysis. The calculation method of ecological compensation standard was established by calculating annual total emergy of ecological service function increment since the starting year of returning cropland to lake, and the annual ecological compensation standard and compensation area were analyzed from 1999 to 2010. The results indicated that ecological compensation standard from 1999 to 2010 was 40.31-86.48 yuan x m(-2) with the mean of 57.33 yuan x m(-2). The ecological compensation standard presented an increase trend year by year due to the effect of eco-recovery of returning cropland to lake. The ecological compensation standard in the research area presented a swift and steady growth trend after 2005 mainly due to the intensive economy development of Hunan Province, suggesting the value of natural ecological resources would increase along with the development of society and economy. Appling the emergy analysis to research the ecological compensation standard could reveal the dynamics of annual ecological compensation standard, solve the abutment problem of matter flow, energy flow and economic flow, and overcome the subjective and arbitrary of environment economic methods. The empirical research of ecological compensation standard in Dongting Lake region showed that the emergy analysis was feasible and advanced.

  10. Regional variability among nonlinear chlorophyll-phosphorus relationships in lakes

    USGS Publications Warehouse

    Filstrup, Christopher T.; Wagner, Tyler; Soranno, Patricia A.; Stanley, Emily H.; Stow, Craig A.; Webster, Katherine E.; Downing, John A.

    2014-01-01

    The relationship between chlorophyll a (Chl a) and total phosphorus (TP) is a fundamental relationship in lakes that reflects multiple aspects of ecosystem function and is also used in the regulation and management of inland waters. The exact form of this relationship has substantial implications on its meaning and its use. We assembled a spatially extensive data set to examine whether nonlinear models are a better fit for Chl a—TP relationships than traditional log-linear models, whether there were regional differences in the form of the relationships, and, if so, which regional factors were related to these differences. We analyzed a data set from 2105 temperate lakes across 35 ecoregions by fitting and comparing two different nonlinear models and one log-linear model. The two nonlinear models fit the data better than the log-linear model. In addition, the parameters for the best-fitting model varied among regions: the maximum and lower Chl aasymptotes were positively and negatively related to percent regional pasture land use, respectively, and the rate at which chlorophyll increased with TP was negatively related to percent regional wetland cover. Lakes in regions with more pasture fields had higher maximum chlorophyll concentrations at high TP concentrations but lower minimum chlorophyll concentrations at low TP concentrations. Lakes in regions with less wetland cover showed a steeper Chl a—TP relationship than wetland-rich regions. Interpretation of Chl a—TP relationships depends on regional differences, and theory and management based on a monolithic relationship may be inaccurate.

  11. Utilization of a Marketing Strategy at Naval Regional Medical Center Great Lakes, Great Lakes, Illinois

    DTIC Science & Technology

    1983-06-01

    22 Analysis of the Mare.....................22 Development of the Marketing Mix .. .......... 29 A Marketing Mix --Recommendations...problem. Marketing strategy, marketing mix and ultimately the marketing orientation will allow hospitals to persevere and possibly thrive in a somewhat...market are currently being met at Naval Regional Medical Center Great Lakes. The fourth objective is to demonstrate an appropriate marketing mix for

  12. Spatial and temporal ecological risk assessment of unionized ammonia nitrogen in Tai Lake, China (2004-2015).

    PubMed

    Li, Yabing; Xu, Elvis Genbo; Liu, Wei; Chen, Yi; Liu, Hongling; Li, Di; Liu, Zhengtao; Giesy, John P; Yu, Hongxia

    2017-06-01

    Ammonia toxicity varies largely due to its pH- and temperature-dependent speciation (unionized ammonia nitrogen, NH3-N). The seasonal and long-term trend of ammonia risk in ecologically significant sections of Tai Lake, China was unknown. In this study, a two-level (deterministic and quantitative) method was developed to assess the special ecological risks posed by NH3-N at 37 sites during two seasons (February and September) of 2014 in Tai Lake. The long-term temporal (2004-2015) risk posed by NH3-N was also assessed by comparing annual quantitative risk values (probability of exceeding acute or chronic threshold values) in three key sections of Tai Lake. The results indicated the species living in the Tai Lake were at a 0.04% and 32.45% chance of risk due to acute exposure, and a 1.97% and 92.05% chance of risk due to chronic exposure in February and September of 2014, respectively. Alarmingly, the chronic ecological risks of NH3-N in the Lanshanzui section of the Tai Lake remained >30% from 2004 to 2011. The chronic risk of NH3-N in all three key sections of Tai Lake started to decrease in 2011. This was likely the consequence of the control practice of eutrophication implemented in the Tai Lake. A significant decline in diversity of the benthic invertebrate community of the Tai Lake could be associated with continuous exposure to ammonia over decades given different sensitivity of taxa to ammonia. The results laid a scientific foundation for risk assessment and management of ammonia in Tai Lake, China, and the developed two-level risk assessment approach can also be applied to other similar aquatic regions.

  13. Wind energy resource atlas. Volume 3. Great Lakes Region

    SciTech Connect

    Paton, D.L.; Bass, A.; Smith, D.G.; Elliott, D.L.; Barchet, W.R.; George, R.L.

    1981-02-01

    The Great Lakes Region atlas assimilates six collections of wind resource data, one for the region and one for each of the five states that compose the Great Lakes region: Illinois, Indiana, Michigan, Ohio, Wisconsin. At the state level, features of the climate, topography, and wind resource are discussed in greater detail than in the regional discussion and the data locations on which the assessment is based are mapped. Variations over several time scales in the wind resource at selected stations in each state are shown on graphs of monthly average and interannual wind speed and power, and of hourly average wind speed for each season. Other graphs present speed, direction, and duration frequencies of the wind at these locations.

  14. Winter and Summer Views of the Salt Lake Region

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Magnificent views of the region surrounding Salt Lake City, Utah are captured in these winter and summer images from the Multi-angle Imaging SpectroRadiometer's vertical-viewing (nadir) camera. Salt Lake City, situated near the southeastern shore of the Great Salt Lake, is host to the 2002 Winter Olympic Games, which open Friday, February 8. Venues for five of the scheduled events are at city (indoor) locations, and five in mountain (outdoor) facilities. All ten can be found within the area contained in these images. Some of the outdoor events take place at Ogden, situated north of Salt Lake City and at Park City, located to the east.

    Salt Lake City is surrounded by mountains including the Wasatch Range to the east, and the temperature difference between the Great Salt Lake and the overlying atmosphere enhances the moisture content of winter storms. These factors, in combination with natural cloud seeding by salt crystals from the lake, are believed to result in greater snowfall in neighboring areas compared to more distant locales.

    In addition to the obvious difference in snow cover between the winter and summer views, water color changes in parts of the Great Salt Lake are apparent in these images. The distinctly different coloration between the northern and southern arms of the Great Salt Lake is the result of a rock-filled causeway built in 1953 to support a permanent railroad. The causeway has resulted in decreased circulation between the two arms and higher salinity on the northern side. The southern part of the lake includes the large Antelope Island, and at full resolution a bridge connecting it to the mainland can be discerned.

    These images are natural color views acquired on February 8, 2001 and June 16, 2001, during Terra orbits 6093 and 7957, respectively. Each image represents an area of about 220 kilometers x 285 kilometers.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth

  15. Great Lakes/St. Lawrence Seaway Regional Transportation Study; Great Lakes Area Industries.

    DTIC Science & Technology

    1981-11-01

    Regional Transportation Study is an element of this planning process . The objective of the GL/SLS Regional Transportation Study is to develop an up-to-date...system performance and ability to process future cargo flows Evaluation of the performance and economic feasibility of improvements to increase the...section is organized as follows: Basic steelmaking processes Production centers in the U.S. and Canada The industry in the Great Lakes area. These

  16. Wind and submerged aquatic vegetation influence bio-optical properties in large shallow Lake Taihu, China

    NASA Astrophysics Data System (ADS)

    Liu, Xiaohan; Zhang, Yunlin; Yin, Yan; Wang, Mingzhu; Qin, Boqiang

    2013-06-01

    studied the bio-optical properties and sediment dynamics of typical phytoplankton-dominated (PD) and macrophyte-dominated (MD) regions in shallow Lake Taihu in China, from long-term site-specific studies and short-term high-frequency observations. The long-term studies showed that five parameters were significantly lower in the MD region than in the PD region: photosynthetically active radiation (PAR) diffuse attenuation coefficient (Kd(PAR)), concentrations of total suspended matter (CTSM), tripton (CTripton), and phytoplankton pigment (CChla+Pa), and CDOM absorption coefficient (aCDOM(350)). In winter in the MD region, with only scarce submerged aquatic vegetation (SAV) coverage, the Kd(PAR), CTSM, and CTripton were significantly higher than in the PD region with no SAV; in contrast, CChla+Pa and aCDOM(350) were significantly lower in the MD region than in the PD region. In the other three seasons with high SAV coverage, Kd(PAR), CTSM, CTripton, CChla+Pa, and aCDOM(350) were all significantly lower in the MD region than in the PD region. The appearance and growth of SAV decreased CTSM, CTripton, and Kd(PAR). The short-term high-frequency study showed that phytoplankton and tripton absorption coefficients were significantly lower in the MD region than in the PD region. In the PD region, there were highly significant exponential relationships between wind speed, wave height, and wave shear stress, and CTripton and Kd(PAR), showing that wind-driven sediment resuspension could significantly affect both the tripton concentration and PAR attenuation. However, in the MD region, there were only weakly significant correlations, or no significant correlations, between wind speed, wave height, and wave shear stress, and CTripton, and Kd(PAR). The combination of the long-term site-specific and short-term high-frequency observations is an excellent tool for study of the bio-optical properties in lake environments.

  17. Economic development influences on sediment-bound nitrogen and phosphorus accumulation of lakes in China.

    PubMed

    Ni, Zhaokui; Wang, Shengrui

    2015-12-01

    China has been confronted with serious water quality deterioration concurrent with rapid socioeconomic progress during the past 40 years. Consequently, knowledge about economic growth and lake water quality dynamics is important to understand eutrophication processes. Objectives were to (i) reconstruct historical nutrient accumulation and the basin economic progress on burial flux (BF); (ii) determine forms and structures of nitrogen (N) and phosphorus (P) in sediment and water using six cores in three of the most severely eutrophic lake areas in China (i.e., Eastern Plain, Yunnan-Guizhou Plain, and Inner Mongolia-Xinjiang regions). Results suggest that BFs of total nitrogen (TN) continued to increase in sediment, whereas total phosphorus (TP) levels were consistent or only slightly increased, except in highly polluted lakes during the past decades. Similar results were observed for concentrations of nutrients in water (i.e., increased N/P). This historical distribution pattern was correlated to long-term fertilization practices of farmers in the watershed (N fertilization exceeds that of P) and was contingent upon pollution control policies (e.g., emphasized P whereas N was ignored). Vertical profiles of BFs indicated that lake nutrient accumulation included three stages in China. Nutrient accumulation started in the 1980s, accelerated from the 1990s, and then declined after 2000. Before the 1980s, nutrients were relatively low and stable, with nutrient inputs being controlled by natural processes. Thereafter, N- and P-bound sediments dramatically increased due to the increasing influence of anthropogenic processes. Nutrients were primarily derived from industries and domestic sewage. After 2000, BFs of nutrients were steady and even decreased, owing to implementation of watershed load reduction policies. The decreasing NaOH-extracted P (Fe/Al-P) and increasing organic phosphorus (OP) indicated that the source of exogenous pollution underwent a shift. Inputs of

  18. Source apportionment of sediment-associated aliphatic hydrocarbon in a eutrophicated shallow lake, China.

    PubMed

    Wang, Ji-Zhong; Yang, Ze-Yu; Chen, Tian-Hu

    2012-11-01

    Chaohu Lake, one of the most eutrophicated lakes in China, has been suffering from long-term outside pollution, urban sewage, river outflows, and agricultural runoff which expectedly have been the main contributors of hydrocarbons. However, the contributions from these various sources have not been specified. The present study is aimed at identifying the potential sources of hydrocarbons in surface sediment around the whole lake and assessing the relative contributions using principal components analysis-multiple linear regression (PCA-MLR). Sixty-one surface sediments covering the whole Chaohu Lake and three main estuaries of inflowing rivers were collected, dried, extracted, and analyzed for 27 normal alkanes (n-alkanes, from C(12) to C(38), defined Σ(27)AH) and unresolved complex mixture (UCM) by GC/MS. Diagnostic ratios and PCA-MLR were utilized to apportion their sources. The concentrations of Σ(27)AH and UCM ranged from 434 to 3,870 ng/g and 11.9 to 325 μg/g dry weight, respectively, for all samples. The concentrations of Σ(27)AH in western region and estuary of Nanfei River were slightly higher but without statistical significance than those from eastern region and estuaries of Yuxi River and Hangbu River. The concentration of UCM from western region was significantly higher than that obtained from eastern region. These results reflect the importance of input of urban runoff by Nanfei River and serious eutrophication in western region. Aliphatic hydrocarbons in Chaohu Lake were mainly derived from high plant wax with mixed sources of phytoplankton and petroleum. Weak microbial decomposition of n-alkanes would be expected to occur from the low ratios of isoprenoid hydrocarbons pristine (pri) and phytane (phy) to n-C(17) and n-C(18), respectively. Higher plant, fossil combustion, petroleum residue, and phytoplankton were proposed as the main origines of aliphatic hydrocarbons by PCA while the contributions of individual n-alkane homologues, pri and phy

  19. Sedimentary record of polycyclic aromatic hydrocarbons and DDTs in Dianchi Lake, an urban lake in Southwest China.

    PubMed

    Guo, Jian-yang; Wu, Feng-chang; Liao, Hai-qing; Zhao, Xiao-li; Li, Wen; Wang, Jing; Wang, Li-fang; Giesy, John P

    2013-08-01

    Unique time trends of polycyclic aromatic hydrocarbons (PAHs) and dichlorodiphenyltrichloroethanes (DDTs) were found in a dated sediment core from Dianchi Lake (DC), an urban lake in Southwest China. The temporal trend of PAHs in DC was not only different from those in China's coastline and remote lakes of China, but also different from those in more developed countries. Identification of sources suggested that PAHs in DC originated primarily from domestic combustion of coal and biomass. However, a change of source from low- and moderate-temperature combustion to high-temperature combustion processes was observed. Different from those in China's coastline and some developed countries, the temporal trend of DDTs in DC mirrored the historical usage of DDTs in China, with erosion of soils and surface runoff from its drainage area the most likely routes of DDT introduction to the lake. Rapid urbanization and industrialization in its catchment, effective interception of point-source pollution, and changes in sources of energy during the last few decades have significantly influenced the vertical profiles of PAHs in DC.

  20. Holocene lake level fluctuations of a small alpine lake in the Qilian Mountains, NW China: a comparison of chironomid, ostracod, pollen and geochemistry data.

    NASA Astrophysics Data System (ADS)

    Mischke, S.; Herzschuh, U.

    2003-04-01

    A core of 14 m length was drilled in a small alpine lake in the Qilian Mountains, NW China. The lake Luanhaizi has a drainage area of about 30 km2 and is situated at an altitude of 3200 m which represents the altitude of the present regional upper timberline. Due to the small size of the open-basin lake (surface area about 1 km2) and the sharply outlined catchment area the lake is regarded as a very sensitively and rapidly responding ecosystem. Analyses of ostracod shells, head capsules of larval chironomids and pollen and spores were conducted and the organic and carbonate content (LOI), element concentrations and magnetic susceptibility of core samples determined. Ostracod taxa mainly comprise Candona candida, C. neglecta, C. rawsoni, Cyclocypris ovum, Cypridopsis vidua, Fabaeformiscandona caudata, F. danielopoli, F. hyalina, Herpetocypris chevreuxi, Heterocypris salina, Ilyocypris cf. bradyi, I. echinata, I. lacustris and Limnocythere inopinata. They may be used to distinguish periods of low lake levels corresponding to a dense cover of aquatic plants at the lake bottom from stages of higher lake levels and a corresponding decrease in macrophytes at the core site. Chironomid taxa belonging to Chironomus, Cladopelma, Glyptotendipes, Micropsectra, Paratanytarsus, Polypedilum, Psectrocladius and Tanytarsus further provide information on variations in benthic oxygen availability and lake level fluctuations. Several units of the core show high abundances of pollen and spores of higher aquatic and wetland plants and fungi (Cyperaceae, Hippuris, Myriophyllum and Glomus) indicating low lake levels. In contrast, algae such as Botryococcus, Pediastrum and Tetraedron were regarded to reflect higher water levels. Typha angustifolia-type, Typha latifolia, Alisma and Potamogeton were recorded in low abundances as well. The organic content of core samples averages 6 % displaying four alternating stages of distinct minima and maxima. Lowest values of about 1 % occur at the core

  1. Dramatic variations in emergent wetland area in China's largest freshwater lake, Poyang Lake

    NASA Astrophysics Data System (ADS)

    Mei, Xuefei; Dai, Zhijun; Fagherazzi, Sergio; Chen, Jiyu

    2016-10-01

    Freshwater wetlands are important ecosystems experiencing rapid degradation around the world. As much as 64% of world's wetland area has been lost since 1900; the situation is even more serious in Asia, where land reclamation and anthropogenic modifications of rivers are increasing the rate of wetland disappearance. In this study, we provide a first complete estimation of daily Emergent Wetland Area (EWA) in Poyang Lake, China's largest freshwater lake, from 1955 to 2012. A wavelet analysis indicates a strong periodicity in the monthly EWA time series with two oscillations having a period of 12 and 60-72 months, respectively. A dramatic increase in mean annual EWA is detected since 2003, when the Three Gorges Dam (TGD) was completed, mainly due to the seasonal drying of 1078 km2 of wetlands in October. It is found that the timing of wetland emergence during the dry season has been anticipated of one month, from November to October, since the establishment of TGD. It is argued that a significant increase in wetland exposure and an observable shift in the seasonal timing of flooding and drying will seriously degrade the wetland system and threaten the endangered migratory birds that inhabit it unless effective countermeasures are implemented.

  2. Heavy metal pollution of lakes along the mid-lower reaches of the Yangtze River in China: intensity, sources and spatial patterns.

    PubMed

    Zeng, Haiao; Wu, Jinglu

    2013-02-26

    Lakes in the middle and lower reaches of the Yangtze River form a shallow lake group unique in the World that is becoming increasingly polluted by heavy metals. Previous studies have largely focused on individual lakes, with limited exploration of the regional pattern of heavy metal pollution of the lake group in this area. This paper explores the sources, intensity and spatial patterns of heavy metal pollution of lake sediments. A total of 45 sample lakes were selected and the concentrations of key metal elements in the sediments of each lake were measured. The cluster analysis (CA), principal component analysis (PCA) and Geo-accumulation index (I(g)) analysis permitted analysis of the source and pollution intensity of the target lakes. Results suggested a notable spatial variation amongst the sample lakes. Lakes in the upper part of the lower reach of the Yangtze River surrounded by typical urban landscapes were strongly or extremely polluted, with high concentrations of Pb, Zn, Cu and Cd in their sediments. This was attributed to large amount of untreated industrial discharges and municipal sewage produced within the lake catchments. In contrast, the heavy-metal pollution of lakes in the Taihu Delta area was notably lower due to industrial restructuring and implementation of effective environmental protection measures. Lakes along the middle reach of Yangtze River surrounded by agricultural areas were unpolluted to moderately polluted by heavy metals overall. Our results suggested that lakes in the central part of China require immediate attention and efforts should be made to implement management plans to prevent further degradation of water quality in these lakes.

  3. Heavy Metal Pollution of Lakes along the Mid-Lower Reaches of the Yangtze River in China: Intensity, Sources and Spatial Patterns

    PubMed Central

    Zeng, Haiao; Wu, Jinglu

    2013-01-01

    Lakes in the middle and lower reaches of the Yangtze River form a shallow lake group unique in the World that is becoming increasingly polluted by heavy metals. Previous studies have largely focused on individual lakes, with limited exploration of the regional pattern of heavy metal pollution of the lake group in this area. This paper explores the sources, intensity and spatial patterns of heavy metal pollution of lake sediments. A total of 45 sample lakes were selected and the concentrations of key metal elements in the sediments of each lake were measured. The cluster analysis (CA), principal component analysis (PCA) and Geo-accumulation index (Ig) analysis permitted analysis of the source and pollution intensity of the target lakes. Results suggested a notable spatial variation amongst the sample lakes. Lakes in the upper part of the lower reach of the Yangtze River surrounded by typical urban landscapes were strongly or extremely polluted, with high concentrations of Pb, Zn, Cu and Cd in their sediments. This was attributed to large amount of untreated industrial discharges and municipal sewage produced within the lake catchments. In contrast, the heavy-metal pollution of lakes in the Taihu Delta area was notably lower due to industrial restructuring and implementation of effective environmental protection measures. Lakes along the middle reach of Yangtze River surrounded by agricultural areas were unpolluted to moderately polluted by heavy metals overall. Our results suggested that lakes in the central part of China require immediate attention and efforts should be made to implement management plans to prevent further degradation of water quality in these lakes. PMID:23442559

  4. Reconstructing Late Holocene Climate Variability in North East China From Varved Maar Lake Sediments

    NASA Astrophysics Data System (ADS)

    Panizzo, V. N.; Mackay, A. W.; Rioual, P.; Chu, G.; Leng, M. J.

    2008-12-01

    Reconstructing climatic variability over the past c. 2 ka years is recognised as a key PAGES timeframe (focus 2). However few high-resolution records exist from the climate sensitive region of N) China which receives the majority of its precipitation from the east Asian summer monsoon (EASM). Interactions between the EASM and the global climate system have great resonance. Such examples include how the EASM responded to changes in climate over the documented e.g. "Medieval Warm Period" (c. AD 900 - 1300), "Little Ice Age" (c. AD 1350-1850) and recent warming. At present, literature remains contradictory to such environmental changes in NE China over this time-frame due to poor chronological control, low resolution of existing studies and even due to the inexact terminology of these climatic periods. Xiaolongwan Lake (XLW) is a small, closed, maar lake located in the Long Gang Volcanic Field, NE China (42°18'N; 126°19'E). It is at an elevation of 655 m a.s.l. with a maximum depth of 15 m. A varve chronology has been created for a 143 cm composite core (2 cores collected in 2006), and here we present diatoms and organic geochemistry (δ13C, TOC, C/N) evidence for environmental change over the past c. 2 ka years. Results show a gradual change in diatom species, moving from a composition where opportunistic species (e.g. Achnanthidium minutissimum) dominate (between c. 100 BC to 500 years AD) at the beginning of the record to one comprised of benthic/epiphytic species (e.g. Staurosira construens var venter, Punctastriata discoidea, Gomphonema parvulum). The introduction after c. 1850 years AD of the planktonic diatom species, Discotella woltereckii, not previously seen in the record, coincides with recent warming. This may be a response to changing limnological conditions, such as decreasing duration of lake ice-cover. Bulk organic δ13C results conducted on a short core collected from XLW in summer 2007, show that over the past c. 350 years there is a distinct

  5. Box model and 1D longitudinal model of flow and transport in Bosten Lake, China

    NASA Astrophysics Data System (ADS)

    Li, Ning; Kinzelbach, Wolfgang; Li, WenPeng; Dong, XinGuang

    2015-05-01

    Bosten Lake in the southeast of Yanqi Catchment, China, supports the downstream agricultural and natural environments. Over the last few decades the intensive agricultural activities in Yanqi Catchment resulted in decreased lake levels and deteriorated lake water quality. A two-box model is constructed to understand the evolution of lake level and salinity between 1958 and 2008. The two-box model of the lake indicates that the evaporation does have the same trend as the observed lake area and the annual average evaporation agrees with the value obtained from the Penman-Monteith approach. To achieve a correct salt balance, the ratio of outflow concentration and average lake concentration has to be around 0.7. This is due to the incomplete mixing of the lake caused by short-circuiting between tributary inflow and the main outflow via the pump stations abstracting water from the lake. This short-circuiting is investigated in more detail by a 1D numerical flow and transport model of the lake calibrated with observations of lake level and lake concentrations. The distributed model reproduces the correct time-varying outflow concentration. It is used for the assessment of two basic management options: increasing river discharge (by water saving irrigation, reduction of phreatic evaporation or reduction of agricultural area) and diverting saline drainage water to the desert. Increasing river discharge to the lake by 20% reduces the east basin salt concentration by 0.55 kg/m3, while capturing all the drainage water and discharging it to depressions instead of the lake reduces the east basin salt concentration by 0.63 kg/m3. A combination of increasing river inflow and decreasing drainage salt flux is sufficient to bring future lake TDS below the required 1 kg/m3, to keep a lake level that sustains the lake ecosystem, and to supply more water for downstream development and ecosystem rehabilitation.

  6. Investigation of avian influenza infections in wild birds, poultry and humans in Eastern Dongting Lake, China.

    PubMed

    Shi, Jinghong; Gao, Lidong; Zhu, Yun; Chen, Tao; Liu, Yunzhi; Dong, Libo; Liu, Fuqiang; Yang, Hao; Cai, Yahui; Yu, Mingdong; Yao, Yi; Xu, Cuilin; Xiao, Xiangming; Shu, Yuelong

    2014-01-01

    We investigated avian influenza infections in wild birds, poultry, and humans at Eastern Dongting Lake, China. We analyzed 6,621 environmental samples, including fresh fecal and water samples, from wild birds and domestic ducks that were collected from the Eastern Dongting Lake area from November 2011 to April 2012. We also conducted two cross-sectional serological studies in November 2011 and April 2012, with 1,050 serum samples collected from people exposed to wild birds and/or domestic ducks. Environmental samples were tested for the presence of avian influenza virus (AIV) using quantitative PCR assays and virus isolation techniques. Hemagglutination inhibition assays were used to detect antibodies against AIV H5N1, and microneutralization assays were used to confirm these results. Among the environmental samples from wild birds and domestic ducks, AIV prevalence was 5.19 and 5.32%, respectively. We isolated 39 and 5 AIVs from the fecal samples of wild birds and domestic ducks, respectively. Our analysis indicated 12 subtypes of AIV were present, suggesting that wild birds in the Eastern Dongting Lake area carried a diverse array of AIVs with low pathogenicity. We were unable to detect any antibodies against AIV H5N1 in humans, suggesting that human infection with H5N1 was rare in this region.

  7. Lake states regional forest resources assessments: Technical papers. Forest Service general technical report

    SciTech Connect

    Webster, H.H.; Vasievich, J.M.

    1997-07-23

    Contains 21 technical working papers prepared for the Lake States regional forest resources assessment, Lake States Forestry Alliance 1995. They represent significant contributions from many individuals and organizations and form the technical background for the Assessment.

  8. Regional characteristics of dust storms in China

    NASA Astrophysics Data System (ADS)

    Qian, Weihong; Tang, Xu; Quan, Linsheng

    2004-09-01

    Regional characteristics of dust storms in northern China are analyzed using a rotated empirical orthogonal function (REOF), based on the annual days of dust storms from 1954 to 1998. The relationships between regional dust storms corresponding to other factors such as precipitation and temperature are explored. The results show that five leading modes of dust storms exist in the following areas: the Taklamakan Desert (Tarim Basin) over the Xinjiang region (far northwestern China), the eastern part of Inner Mongolia (North China), the Tsaidam Basin, the Tibetan Plateau, and the upper reaches of the Yellow River (Gobi Desert). These areas are associated with an arid climate and frequent winds. For the first mode in the Tarim Basin, most dust storms appear in the 1980s, while dust storms become less frequent in the 1990s. The second mode (North China) shows the highest frequency of dust storms in the mid-1960s but the frequency decreases afterward. The third mode indicates a decreasing trend of annual dust storms after the mid-1960s but with a high interannual variability. The fourth mode also shows a decreasing trend but with a low interannual variability. The fifth mode displays a high frequency of dust storms in the 1970s followed by a decreasing trend. For the five modes of dust storm distribution, four of the centers are located in desert regions. The annual dust storms of a selected station in each mode region are shown to compare the coefficient time series of these modes. The negative correlation between the prior winter temperature and dust storm frequency is identified for most stations. There is no consistency in the correlation between the dust storm frequency and the annual rainfall as well as the prior winter rainfall at these stations. The activity of dust storms in northern China are directly linked to the cyclone activity, especially for the interdecadal variability.

  9. Nitrogen deposition to lakes in national parks of the western Great Lakes region: Isotopic signatures, watershed retention, and algal shifts

    NASA Astrophysics Data System (ADS)

    Hobbs, William O.; Lafrancois, Brenda Moraska; Stottlemyer, Robert; Toczydlowski, David; Engstrom, Daniel R.; Edlund, Mark B.; Almendinger, James E.; Strock, Kristin E.; VanderMeulen, David; Elias, Joan E.; Saros, Jasmine E.

    2016-03-01

    Atmospheric deposition is a primary source of reactive nitrogen (Nr) to undisturbed watersheds of the Great Lakes region of the U.S., raising concerns over whether enhanced delivery over recent decades has affected lake ecosystems. The National Atmospheric Deposition Program (NADP) has been measuring Nr deposition in this region for over 35 years. Here we explore the relationships among NADP-measured Nr deposition, nitrogen stable isotopes (δ15N) in lake sediments, and the response of algal communities in 28 lakes situated in national parks of the western Great Lakes region of the U.S. We find that 36% of the lakes preserve a sediment δ15N record that is statistically correlated with some form of Nr deposition (total dissolved inorganic N, nitrate, or ammonium). Furthermore, measured long-term (since 1982) nitrogen biogeochemistry and inferred critical nitrogen loads suggest that watershed nitrogen retention and climate strongly affect whether sediment δ15N is related to Nr deposition in lake sediment records. Measurements of algal change over the last ~ 150 years suggest that Nr deposition, in-lake nutrient cycling, and watershed inputs are important factors affecting diatom community composition, in addition to direct climatic effects on lake physical limnology. The findings suggest that bulk sediment δ15N does reflect Nr deposition in some instances. In addition, this study highlights the interactive effects of Nr deposition and climate variability.

  10. Quantifying regional vegetation cover variability in North China during the Holocene: implications for climate feedback.

    PubMed

    Liu, Guo; Yin, Yi; Liu, Hongyan; Hao, Qian

    2013-01-01

    Validating model simulations of vegetation-climate feedback needs information not only on changes in past vegetation types as reconstructed by palynologists, but also on other proxies such as vegetation cover. We present here a quantitative regional vegetation cover reconstruction for North China during the Holocene. The reconstruction was based on 15 high-quality lake sediment profiles selected from 55 published sites in North China, along with their modern remote sensing vegetation index. We used the surface soil pollen percentage to build three pollen-vegetation cover transfer models, and used lake surface sediment pollen data to validate their accuracy. Our results showed that vegetation cover in North China increased slightly before its maximum at 6.5 cal ka BP and has since declined significantly. The vegetation decline since 6.5 cal ka BP has likely induced a regional albedo change and aerosol increase. Further comparison with paleoclimate and paleovegetation dynamics in South China reproduced the regional cooling effect of vegetation cover decline in North China modelled in previous work. Our discussion demonstrates that, instead of reconstructing vegetation type from a single site, reconstructing quantitative regional vegetation cover could offer a broader understanding of regional vegetation-climate feedback.

  11. Quantifying Regional Vegetation Cover Variability in North China during the Holocene: Implications for Climate Feedback

    PubMed Central

    Liu, Guo; Yin, Yi; Liu, Hongyan; Hao, Qian

    2013-01-01

    Validating model simulations of vegetation-climate feedback needs information not only on changes in past vegetation types as reconstructed by palynologists, but also on other proxies such as vegetation cover. We present here a quantitative regional vegetation cover reconstruction for North China during the Holocene. The reconstruction was based on 15 high-quality lake sediment profiles selected from 55 published sites in North China, along with their modern remote sensing vegetation index. We used the surface soil pollen percentage to build three pollen-vegetation cover transfer models, and used lake surface sediment pollen data to validate their accuracy. Our results showed that vegetation cover in North China increased slightly before its maximum at 6.5 cal ka BP and has since declined significantly. The vegetation decline since 6.5 cal ka BP has likely induced a regional albedo change and aerosol increase. Further comparison with paleoclimate and paleovegetation dynamics in South China reproduced the regional cooling effect of vegetation cover decline in North China modelled in previous work. Our discussion demonstrates that, instead of reconstructing vegetation type from a single site, reconstructing quantitative regional vegetation cover could offer a broader understanding of regional vegetation-climate feedback. PMID:23977110

  12. Regional species pools control community saturation in lake phytoplankton.

    PubMed

    Ptacnik, Robert; Andersen, Tom; Brettum, Pål; Lepistö, Liisa; Willén, Eva

    2010-12-22

    Recent research has highlighted that positive biodiversity-ecosystem functioning relationships hold for all groups of organisms, including microbes. Yet, we still lack understanding regarding the drivers of microbial diversity, in particular, whether diversity of microbial communities is a matter of local factors, or whether metacommunities are of similar importance to what is known from higher organisms. Here, we explore the driving forces behind spatial variability in lake phytoplankton diversity in Fennoscandia. While phytoplankton biovolume is best predicted by local phosphorus concentrations, phytoplankton diversity (measured as genus richness, G) only showed weak correlations with local concentrations of total phosphorus. By estimating spatial averages of total phosphorus concentrations on various scales from an independent, spatially representative lake survey, we found that close to 70 per cent of the variability in local phytoplankton diversity can be explained by regionally averaged phosphorus concentrations on a scale between 100 and 400 km. Thus, the data strongly indicate the existence of metacommunities on this scale. Furthermore, we show a strong dependency between lake productivity and spatial community turnover. Thus, regional productivity affects beta-diversity by controlling spatial community turnover, resulting in scale-dependent productivity-diversity relationships. As an illustration of the interaction between local and regional processes in shaping microbial diversity, our results offer both empirical support and a plausible mechanism for the existence of common scaling rules in both the macrobial and the microbial worlds. We argue that awareness of regional species pools in phytoplankton and other unicellular organisms may critically improve our understanding of ecosystems and their susceptibility to anthropogenic stressors.

  13. Great Lakes Biomass State and Regional Partnership (GLBSRP)

    SciTech Connect

    Kuzel, Frederic

    2009-09-01

    The Council of Great Lakes Governors administered the Great Lakes Biomass State and Regional Partnership (GLBSRP) under contract with the U. S. Department of Energy (DOE). This Partnership grew out of the existing Regional Biomass Energy Program which the Council had administered since 1983. The GLBSRP includes the States of Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio and Wisconsin. The GLBSRP's overall goal is to facilitate the increased production and use of bioenergy and biobased products throughout the region. The GLBSRP has traditionally addressed its goals and objectives through a three-pronged approach: providing grants to the States; undertaking region-wide education, outreach and technology transfer projects; and, providing in-house management, support and information dissemination. At the direction of US Department of Energy, the primary emphasis of the GLBSRP in recent years has been education and outreach. Therefore, most activities have centered on developing educational materials, hosting workshops and conferences, and providing technical assistance. This report summarizes a selection of activities that were accomplished under this cooperative agreement.

  14. Local to regional emission sources affecting mercury fluxes to New York lakes

    NASA Astrophysics Data System (ADS)

    Bookman, Revital; Driscoll, Charles T.; Engstrom, Daniel R.; Effler, Steven W.

    Lake-sediment records across the Northern Hemisphere show increases in atmospheric deposition of anthropogenic mercury (Hg) over the last 150 years. Most of the previous studies have examined remote lakes affected by the global atmospheric Hg reservoir. In this study, we present Hg flux records from lakes in an urban/suburban setting of central New York affected also by local and regional emissions. Sediment cores were collected from the Otisco and Skaneateles lakes from the Finger Lakes region, Cross Lake, a hypereutrophic lake on the Seneca River, and Glacial Lake, a small seepage lake with a watershed that corresponds with the lake area. Sediment accumulation rates and dates were established by 210Pb. The pre-anthropogenic regional atmospheric Hg flux was estimated to be 3.0 μg m -2 yr -1 from Glacial Lake, which receives exclusively direct atmospheric deposition. Mercury fluxes peaked during 1971-2001, and were 3 to more than 30 times greater than pre-industrial deposition. Land use change and urbanization in the Otisco and Cross watersheds during the last century likely enhanced sediment loads and Hg fluxes to the lakes. Skaneateles and Glacial lakes have low sediment accumulation rates, and thus are excellent indicators for atmospheric Hg deposition. In these lakes, we found strong correlations with emission records for the Great Lakes region that markedly increased in the early 1900s, and peaked during WWII and in the early 1970s. Declines in modern Hg fluxes are generally evident in the core records. However, the decrease in sediment Hg flux at Glacial Lake was interrupted and has increased since the early 1990s probably due to the operation of new local emission sources. Assuming the global Hg reservoir tripled since the pre-industrial period, the contribution of local and regional emission sources to central New York lakes was estimated to about 80% of the total atmospheric Hg deposition.

  15. The reflectance and fluorescence properties of Adirondack mountain region lakes applied to the remote sensing of lake chemistry

    SciTech Connect

    Vertucci, F.A.

    1988-01-01

    This study defines the feasibility of the remote monitoring of lake chemistry in the Adirondack Region of New York. The purpose of this thesis is to determine the relationship between the optical properties of lakes and their chemical constituents. The work is intended to derive useful relationships between lake chemistry and lake spectral properties so that lake chemistry can be estimated by remote means. Chemical constituents associated with lake acidification are of particular interest. Constituents of the water column which are known to directly affect lake optical properties (plant pigments, dissolved organic carbon (DOC) and turbidity) correlated well with field reflectance measurements and allowed for a consistent prediction of the concentrations of these constituents using reflectance measurements. However, parameters associated with acidification (pH, alkalinity and aluminum concentrations) correlated poorly with reflectance measurements and no models for prediction of these constituents were possible. A relationship does exist between DOC and fluorescence intensity and also between lake pH, aluminum and DOC concentrations and spectral fluorescence and intensity. In the Adirondack Region, water column constituents which directly affect lake optical properties may e remotely estimated with reflectance measures while constituents correlated with DOC composition may be estimated by laser fluorsensing, including pH and aluminum.

  16. 40 CFR 81.67 - Lake Michigan Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Quality Control Regions § 81.67 Lake Michigan Intrastate Air Quality Control Region. The Menominee-Escanaba (Michigan)-Marinette (Wisconsin) Interstate Air Quality Control Region has been renamed the Lake Michigan Intrastate Air Quality Control Region (Wisconsin) and revised to consist of the territorial...

  17. 40 CFR 81.67 - Lake Michigan Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Quality Control Regions § 81.67 Lake Michigan Intrastate Air Quality Control Region. The Menominee-Escanaba (Michigan)-Marinette (Wisconsin) Interstate Air Quality Control Region has been renamed the Lake Michigan Intrastate Air Quality Control Region (Wisconsin) and revised to consist of the territorial...

  18. 40 CFR 81.67 - Lake Michigan Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Quality Control Regions § 81.67 Lake Michigan Intrastate Air Quality Control Region. The Menominee-Escanaba (Michigan)-Marinette (Wisconsin) Interstate Air Quality Control Region has been renamed the Lake Michigan Intrastate Air Quality Control Region (Wisconsin) and revised to consist of the territorial...

  19. 40 CFR 81.67 - Lake Michigan Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Quality Control Regions § 81.67 Lake Michigan Intrastate Air Quality Control Region. The Menominee-Escanaba (Michigan)-Marinette (Wisconsin) Interstate Air Quality Control Region has been renamed the Lake Michigan Intrastate Air Quality Control Region (Wisconsin) and revised to consist of the territorial...

  20. Biological and chemical factors driving the temporal distribution of cyanobacteria and heterotrophic bacteria in a eutrophic lake (West Lake, China).

    PubMed

    Song, Hao; Xu, Jiahui; Lavoie, Michel; Fan, Xiaoji; Liu, Guangfu; Sun, Liwei; Fu, Zhengwei; Qian, Haifeng

    2017-02-01

    Physico-chemical parameters, hydrological conditions, and microbial interactions can affect the growth and persistence of cyanobacteria, but the interacting effects among these bloom-forming factors are still poorly known. This hampers our capacity to predict the occurrence of cyanobacterial bloom accurately. Here, we studied the relationship between temperature, N and P cycles, and the microbial community abundance and diversity at 0.5 m under the surface of West Lake (China) from January 21 to November 20, 2015, in order to better understand the key factors regulating temporal changes in the cyanobacterial community. Using high throughput sequencing of the 16S rRNA gene V3-V4 region, we studied the diversity and abundance of bacteria. In parallel, we measured physico-chemical parameters and followed the abundance of key genes involved in N fixation, denitrification, and nutrient uptake. Multivariate analyses suggest that P concentration and water temperature are the key factors controlling the outbreak of summer cyanobacterial bloom. RT-qPCR analyses of the bacterial community and measurements of the copy number of denitrification-related gene (nirK, nosZ, nirS) show that denitrification potential and denitrifying bacteria relative abundance (Pseudomonas and Bacillus) increased in concert with diazotrophic cyanobacterial genera (Anabaena, Nostoc, Aphanizomenon flos-aquae) and the common bloom-forming non-diazotrophic cyanobacterium genus Microcystis. The present study brings new insights on the complex interplay between physico-chemical parameters, heterotrophic bacterial community composition, nitrogen cycle, and cyanobacteria dominance in a eutrophic lake.

  1. Impacts of Land-Use Changes on the Lakes across the Yangtze Floodplain in China.

    PubMed

    Xie, Cong; Huang, Xin; Mu, Hongqiang; Yin, Wei

    2017-04-04

    The middle and lower Yangtze (MLY) floodplain has one of the most densely distributed lake clusters in China but suffered from long-term lake reclamation and wetland degradation due to intensive cultivation, fish rearing, and urban expansion over the past several decades. As a land-use alternation to support human life, the conversion of lakes to cropland, aquaculture ponds, and human settlements provides essential ecosystem goods at the expense of the deterioration of wetland environment. To quantify the driving factors of lake changes, we investigated the land-use transitions from lakes (≥1 km(2)) between 1975 and 2015 using Landsat remote sensing data. We found that the dramatic decline in lake area (a net decrease of 13.8 ± 1.4%) over the four decades was largely attributed to human-induced transformation from lakes to cropland, fish ponds, and built-up areas, accounting for 34.6%, 24.2%, and 2.5% of the total area reduction, respectively. The remaining loss, associated with vegetation (37.3%) and bare land (1.4%) and coming mainly from China's two largest freshwater lakes (Poyang and Dongting), can be explained by climate variation, sediment deposition, and hydrological regulation. These findings shed new light on the quantitative impacts of human activities and climate variation on lake changes and provide a scientific foundation for wetland management decision-making.

  2. Spatial distribution and multiple sources of heavy metals in the water of Chaohu Lake, Anhui, China.

    PubMed

    Li, Guolian; Liu, Guijian; Zhou, Chuncai; Chou, Chen-Lin; Zheng, Liugen; Wang, Jizhong

    2012-05-01

    In this study, a survey for the spatial distribution of heavy metals in Chaohu Lake of China was conducted. Sixty-two surface water samples were collected from entire lake including three of its main river entrances. This is the first systematic report concerning the content, distribution, and origin of heavy metals (Cu, Cr, Cd, Hg, Zn, and Ni) in the Chaohu Lake water. The results showed that heavy metals (Cu, Cr, Zn, and Ni) concentrations in the estuary of Nanfei River were relatively higher than those in the other areas, while content of Hg is higher in the southeast lake than northwest lake. Moreover, Cd has locally concentration in the surface water from the entire Chaohu Lake. The heavy metal average concentrations, except Hg, were lower than the cutoff values for the first-grade water quality (China Environment Quality Standard) which was set as the highest standard to protect the social nature reserves. The Hg content is between the grades three and four water quality, and other heavy metals contents are higher than background values. The aquatic environment of Chaohu Lake has apparently been contaminated. Both the cluster analysis (CA) and correlation analysis provide information about the origin of heavy metals in the Lake. Our findings indicated that agricultural activities and adjacent plants chimneys may contribute the most to Cd and Hg contamination of Chaohu Lake, respectively.

  3. Air pollution and environmental justice in the Great Lakes region

    NASA Astrophysics Data System (ADS)

    Comer, Bryan

    While it is true that air quality has steadily improved in the Great Lakes region, air pollution remains at unhealthy concentrations in many areas. Research suggests that vulnerable and susceptible groups in society -- e.g., minorities, the poor, children, and poorly educated -- are often disproportionately impacted by exposure to environmental hazards, including air pollution. This dissertation explores the relationship between exposure to ambient air pollution (interpolated concentrations of fine particulate matter, PM2.5) and sociodemographic factors (race, housing value, housing status, education, age, and population density) at the Census block-group level in the Great Lakes region of the United States. A relatively novel approach to quantitative environmental justice analysis, geographically weighted regression (GWR), is compared with a simplified approach: ordinary least squares (OLS) regression. While OLS creates one global model to describe the relationship between air pollution exposure and sociodemographic factors, GWR creates many local models (one at each Census block group) that account for local variations in this relationship by allowing the value of regression coefficients to vary over space, overcoming OLS's assumption of homogeneity and spatial independence. Results suggest that GWR can elucidate patterns of potential environmental injustices that OLS models may miss. In fact, GWR results show that the relationship between exposure to ambient air pollution and sociodemographic characteristics is non-stationary and can vary geographically and temporally throughout the Great Lakes region. This suggests that regulators may need to address environmental justice issues at the neighborhood level, while understanding that the severity of environmental injustices can change throughout the year.

  4. One century sedimentary record of lead and zinc pollution in Yangzong Lake, a highland lake in southwestern China.

    PubMed

    Zhang, Enlou; Liu, Enfeng; Shen, Ji; Cao, Yanmin; Li, Yanling

    2012-01-01

    Reconstruction of trace metal pollution histories and sources may help us to regulate current pollutant discharge. This is especially important for the highland lakes in southwestern China, which are facing trace metals pollution. We present sedimentary records of 11 metals accumulated in Yangzong Lake since the 1870's, a highland lake in southwestern China. Pollution of lead and zinc (Pb and Zn) was differentiated based on principal component analysis, geochemical normalization, and lead isotope ratios. Nearly all the metals as well as grain size composition show generally constant values before the mid-1980's, denoting stable detrital input in the catchment. Fluctuations in the concentrations of the metals as well as grain size composition since the mid-1980's indicate an increase in soil erosion with strengthened human disturbance in the catchment. After geochemical normalization, Pb and Zn showed constant values before 1990 AD and then a gradual increase in parallel with the variations in 208Pb/206Pb and 207Pb/206Pb ratios, indicating that Pb and Zn pollution occurred. Combining the data of 208pb/206Pb and 207Pb/6Pb ratios in the sediments of Yangzong Lake, leaded gasoline, Pb-Zn ore and coal, and consumption or production historical trends, we deduced that the enhanced Pb and Zn pollution in Yangzong Lake is caused primarily by ore mining and refining.

  5. Lake level changes in Hala Lake(NW China) based on ostracodassemblages during the LGM and Post-LGM

    NASA Astrophysics Data System (ADS)

    Yan, D.; Wuennemann, B.

    2012-12-01

    The Hala Lake, located in the Qilian Mountains, Qinghai Province, China, at 4078 m a.s.l. may archive in its sediments hydrological and climate changes during the Late Quaternary time, as it is close to the area impacted by the East-Asian Summer monsoon and westerly-driven air masses. Based on the sediment core H7, which was taken in the center of the lake at 65m water depth,ostracod assemblages and stable isotopes from ostracode shells were investigated in details. Three main species were found, which are common species in high altitude saline lakes of the Tibetan Plateau: Leucocythere sp.,Limnocythereinopinata and Eucypris sp.They started to occur in deeper part of H7,indicating an early onset of favorable living conditions during the LGM and post-LGM periods. Besides, algae occurred between 25 and 32m water depth. According to the unevenly distributed amount of ostracods and oxygen isotope data, our results indicate important lake level changes during the global LGM and Lateglacial. The lake experienced lowest levels of 25-50 m below the present water line. Ostracods disappeared with the onset of the early Holocene.A stepwise refilling started already at ca. 16 kyr BP and reached -25 m level during the Bølling/Allerød warm phase at ca. 13.5 kyr BP.Latest at ca.7.6 kyr BP, the lake reached a stable highstand similar to the present level until ca.6 kyr BPas . The subsequent lake development remains unclear due to strong mismatches of the data but may indicate a general trend to deteriorating conditions and lake level lowstands at ca. 5.0-4.2, 2.0 and at around 0.5 kyr BP.; Ostracods Distribution in H2 ; Ostracods plate in Hala lake

  6. Reconstruction of atmospheric soot history in inland regions from lake sediments over the past 150 years

    PubMed Central

    Han, Y. M.; Wei, C.; Huang, R.-J.; Bandowe, B. A. M.; Ho, S. S. H.; Cao, J. J.; Jin, Z. D.; Xu, B. Q.; Gao, S. P.; Tie, X. X.; An, Z. S.; Wilcke, W.

    2016-01-01

    Historical reconstruction of atmospheric black carbon (BC, in the form of char and soot) is still constrained for inland areas. Here we determined and compared the past 150-yr records of BC and polycyclic aromatic compounds (PACs) in sediments from two representative lakes, Huguangyan (HGY) and Chaohu (CH), in eastern China. HGY only receives atmospheric deposition while CH is influenced by riverine input. BC, char, and soot have similar vertical concentration profiles as PACs in both lakes. Abrupt increases in concentrations and mass accumulation rates (MARs) of soot have mainly occurred since ~1950, the establishment of the People’s Republic of China, when energy usage changed to more fossil fuel contributions reflected by the variations in the concentration ratios of char/soot and individual PACs. In HGY, soot MARs increased by ~7.7 times in the period 1980–2012 relative to the period 1850–1950. Similar increases (~6.7 times) were observed in CH. The increase in soot MARs is also in line with the emission inventory records in the literature and the fact that the submicrometer-sized soot particles can be dispersed regionally. The study provides an alternative method to reconstruct the atmospheric soot history in populated inland areas. PMID:26750586

  7. Reconstruction of atmospheric soot history in inland regions from lake sediments over the past 150 years

    NASA Astrophysics Data System (ADS)

    Han, Y. M.; Wei, C.; Huang, R.-J.; Bandowe, B. A. M.; Ho, S. S. H.; Cao, J. J.; Jin, Z. D.; Xu, B. Q.; Gao, S. P.; Tie, X. X.; An, Z. S.; Wilcke, W.

    2016-01-01

    Historical reconstruction of atmospheric black carbon (BC, in the form of char and soot) is still constrained for inland areas. Here we determined and compared the past 150-yr records of BC and polycyclic aromatic compounds (PACs) in sediments from two representative lakes, Huguangyan (HGY) and Chaohu (CH), in eastern China. HGY only receives atmospheric deposition while CH is influenced by riverine input. BC, char, and soot have similar vertical concentration profiles as PACs in both lakes. Abrupt increases in concentrations and mass accumulation rates (MARs) of soot have mainly occurred since ~1950, the establishment of the People’s Republic of China, when energy usage changed to more fossil fuel contributions reflected by the variations in the concentration ratios of char/soot and individual PACs. In HGY, soot MARs increased by ~7.7 times in the period 1980–2012 relative to the period 1850–1950. Similar increases (~6.7 times) were observed in CH. The increase in soot MARs is also in line with the emission inventory records in the literature and the fact that the submicrometer-sized soot particles can be dispersed regionally. The study provides an alternative method to reconstruct the atmospheric soot history in populated inland areas.

  8. RESEARCH NOTE: A Late Holocene geomagnetic secular variation record from Erhai Lake, southwest China

    NASA Astrophysics Data System (ADS)

    Hyodo, Masayuki; Yoshihara, Arata; Kashiwaya, Kenji; Okimura, Takashi; Masuzawa, Toshiyuki; Nomura, Ryotaro; Tanaka, Shingo; Xing, Tang Bang; Qing, Liu Su; Jian, Liu Shi

    1999-03-01

    A secular variation record of the geomagnetic field direction for the last 6.5 kyr has been obtained from the magnetization of sediment cores from Erhai Lake, southwest China. In order to make a comparison with this record, secular variation in east-central China was investigated by combining available magnetic field data from historical records and archaeomagnetic measurements since about 350 bc. The secular variation in Erhai Lake shows features consistent with the combined record, except for the oldest three observed declination swings in Sian from 720 to 900 ad. Many features of declination and inclination in China also occur in Japan. From 500 to 1000 ad, declination was westerly ranging from about -20° to -5° in Erhai Lake, east-central China, and Japan.

  9. Quantitative Development and Distribution of Zooplankton in Medium Lakes of the Kostanay Region (North Kazakhstan Region)

    ERIC Educational Resources Information Center

    Aubakirova, Gulzhan A.; Syzdykov, Kuanysh N.; Kurzhykayev, Zhumagazy; Uskenov, Rashit B.; Narbayev, Serik; Begenova, Ainagul B.; Zhumakayeva, Aikumys N.; Sabdinova, Dinara K.; Akhmedinov, Serikbay N.

    2016-01-01

    The assessment of water resources plays an important environmental and economic role, since it allows developing an effective program of regional development with regard to the environmental load. The hydro-chemical regime of lakes includes water temperature, content of biogenic elements, total mineralization, oxygen regime, and other parameters…

  10. Moving target feature phenomenology data collection at China Lake

    NASA Astrophysics Data System (ADS)

    Gross, David C.; Hill, Jeff; Schmitz, James L.

    2002-08-01

    This paper describes the DARPA Moving Target Feature Phenomenology (MTFP) data collection conducted at the China Lake Naval Weapons Center's Junction Ranch in July 2001. The collection featured both X-band and Ku-band radars positioned on top of Junction Ranch's Parrot Peak. The test included seven targets used in eleven configurations with vehicle motion consisting of circular, straight-line, and 90-degree turning motion. Data was collected at 10-degree and 17-degree depression angles. Key parameters in the collection were polarization, vehicle speed, and road roughness. The collection also included a canonical target positioned at Junction Ranch's tilt-deck turntable. The canonical target included rotating wheels (military truck tire and civilian pick-up truck tire) and a flat plate with variable positioned corner reflectors. The canonical target was also used to simulate a rotating antenna and a vibrating plate. The target vehicles were instrumented with ARDS pods for differential GPS and roll, pitch and yaw measurements. Target motion was also documented using a video camera slaved to the X-band radar antenna and by a video camera operated near the target site.

  11. Lake Morphometry for NHD Lakes in Souris Red Rainy Region 9 HUC

    EPA Pesticide Factsheets

    Lake morphometry metrics are known to influence productivity in lakes and are important for building various types of ecological and environmental models of lentic systems. The lake morphometry dataset included here contains estimates of Surface Area, Shoreline Length, Shoreline Development, Maximum Depth, Mean Depth, Lake Volume, Maximum Lake Length, Mean Lake Width, Maximum Lake Width, and Fetch for each of the ??lakepond?? waterbodies in the NHDPlus V2. The current release of the datasets is version 0.1 and future refinements to the data are expected.

  12. Isotopic structure of Lake Whitefish in Lake Huron: Evidence for regional and local populations based on resource use

    USGS Publications Warehouse

    Eberts, Rebecca L.; Wissel, Bjorn; Simpson, Gavin L.; Crawford, Stephen S.; Stott, Wendylee; Hanner, Robert H.; Manzon, Richard G.; Wilson, Joanna Y.; Boreham, Douglas R.; Somers, Christopher M.

    2017-01-01

    Lake Whitefish Coregonus clupeaformis is the most commercially valuable species in Lake Huron. The fishery for this species has historically been managed based on 25 management units (17 in Canada, 8 in the USA). However, congruence between the contemporary population structure of Lake Whitefish and management units is poorly understood. We used stable isotopes of carbon (δ13C) and nitrogen (δ15N), food web markers that reflect patterns in resource use (i.e., prey, location, habitat), to assess the population structure of spawning-phase Lake Whitefish collected from 32 sites (1,474 fish) across Lake Huron. We found large isotopic variation among fish from different sites (ranges: δ13C = 10.2‰, δ15N = 5.5‰) and variable niche size and levels of overlap (standard ellipse area = 1.0–4.3‰2). Lake Huron contained spawning-phase fish from four major isotopic clusters largely defined by extensive variation in δ13C, and the isotopic composition of fish sampled was spatially structured both within and between lake basins. Based on cluster compositions, we identified six putative regional groups, some of which represented sites of high diversity (three to four clusters) and others with less (one to two clusters). Analysis of isotopic values from Lake Whitefish collected from summer feeding locations and baseline prey items showed similar isotopic variation and established spatial linkage between spawning-phase and summer fish. Our results show that summer feeding location contributes strongly to the isotopic structure we observed in spawning-phase fish. One of the regional groups we identified in northern Georgian Bay is highly distinct based on isotopic composition and possibly ecologically unique within Lake Huron. Our findings are congruent with several previous studies using different markers (genetics, mark–recapture), and we conclude that current management units are generally too small and numerous to reflect the population structure of Lake Whitefish

  13. Determining the water age of Lake Taihu during the water transfer from Yangtze River, China

    NASA Astrophysics Data System (ADS)

    Li, Yiping; Acharya, Kumud; Zhu, Jianting; Yu, Zhongbo

    2010-05-01

    To improve water quality and alleviate the eutrophication problem for Lake Taihu, the third largest shallow lake in China, water transfer project from Yangtze River, was initiated to dilute the polluted water and export pollutants out of the lake in 2002. The impact of water transfer on transport processes of dissolved substance in the lake is studied by using the concept of water age using a three-dimensional numerical model, Environmental Fluid dynamic Code (EFDC). Influences of inflow tributaries and wind forcing on water age distribution are investigated. Model results show that the effect of water transfer on transport processes in the lake is strongly affected by hydrodynamic conditions induced by wind and inflow/outflow tributaries. Water age in Lake Taihu has highly spatial and temporal heterogeneity, with the mean water age of approximately 130 days in summer and 230 days in other seasons during the simulation year. Southeastly wind, the dominant wind direction in summer, could improve eastern areas of the lake which provide drinking water source and Meiliang Bay, the most polluted bay in the lake. The most efficient flow discharge of transferred water for diluting the lake could be approximately 100 m3/s while considering benefit/cost ratio. Additionally, the water transfer project just minor effects on parts of the lake rather than the entire lake, unless nutrient concentrations in the transferred water are reduced to a reasonable level. This study provides useful information for better understanding the complex hydrodynamic and mass transport processes in the lake, which is important for developing and implementing effective lake management strategies. Keywords: water transfer; water age; EFDC; Lake Taihu; Yangtze River

  14. Assessment of the Distribution, Sources and Potential Ecological Risk of Heavy Metals in the Dry Surface Sediment of Aibi Lake in Northwest China

    PubMed Central

    Abuduwaili, Jilili; Zhang, Zhao yong; Jiang, Feng qing

    2015-01-01

    The distribution, sources and potential ecological risk of heavy metals in the sediment of lakes in eastern China and other areas of the world that have undergone rapid economic development have been widely researched by scholars. However, this is not true for heavy metals in the sediment of rump lakes in the arid regions of China and world-wide. Because of this, we chose Aibi Lake to serve as a typical rump lake in an oasis in an arid area in northwest China for our study. Sediment samples were collected from the lake and then the quantities of the heavy metals Pb, Ni, Cd, Cu, Zn, Hg and Cr were measured. Then using a variety of statistical methods, we analyzed the distribution, sources, pollution status and the potential ecological risk of these metals. The results show that: (1) The amounts of the seven heavy metals all fell within the Second Soil National Standard, but the average and maximum values were all higher than the background values of Xinjiang in northwest China. (2) Multivariate statistical analysis determined that the Cd, Pb, Hg and Zn in the sediment were mainly derived from man-sources, and Cu, Ni, and Cr were mainly from the natural geological background. (3) Enrichment factor analysis and the geo-accumulation index evaluation method show that Cd, Hg and Pb in the surface sediment of the Aibi Lake were at low and partial pollution levels, while Zn, Cr, Ni and Cu were at no and low pollution levels. (4) Calculation of the potential ecological hazards index found that, among the seven tested heavy metals, Cd, Hg and Pb were the main potential ecological risk factors, and the contribution of each was 42.6%, 28.6%, and 24.0%, respectively. Cd is the main potential ecological risk factor, followed by Hg and Pb. This work revealed that recent economic development of the Aibi Lake Basin has negatively influenced the accumulation of heavy metals in the sediments of the lake, and, therefore, we should pay increasing attention to this problem and take

  15. Assessment of the distribution, sources and potential ecological risk of heavy metals in the dry surface sediment of Aibi Lake in northwest China.

    PubMed

    Abuduwaili, Jilili; Zhang, Zhao yong; Jiang, Feng qing

    2015-01-01

    The distribution, sources and potential ecological risk of heavy metals in the sediment of lakes in eastern China and other areas of the world that have undergone rapid economic development have been widely researched by scholars. However, this is not true for heavy metals in the sediment of rump lakes in the arid regions of China and world-wide. Because of this, we chose Aibi Lake to serve as a typical rump lake in an oasis in an arid area in northwest China for our study. Sediment samples were collected from the lake and then the quantities of the heavy metals Pb, Ni, Cd, Cu, Zn, Hg and Cr were measured. Then using a variety of statistical methods, we analyzed the distribution, sources, pollution status and the potential ecological risk of these metals. The results show that: (1) The amounts of the seven heavy metals all fell within the Second Soil National Standard, but the average and maximum values were all higher than the background values of Xinjiang in northwest China. (2) Multivariate statistical analysis determined that the Cd, Pb, Hg and Zn in the sediment were mainly derived from man-sources, and Cu, Ni, and Cr were mainly from the natural geological background. (3) Enrichment factor analysis and the geo-accumulation index evaluation method show that Cd, Hg and Pb in the surface sediment of the Aibi Lake were at low and partial pollution levels, while Zn, Cr, Ni and Cu were at no and low pollution levels. (4) Calculation of the potential ecological hazards index found that, among the seven tested heavy metals, Cd, Hg and Pb were the main potential ecological risk factors, and the contribution of each was 42.6%, 28.6%, and 24.0%, respectively. Cd is the main potential ecological risk factor, followed by Hg and Pb. This work revealed that recent economic development of the Aibi Lake Basin has negatively influenced the accumulation of heavy metals in the sediments of the lake, and, therefore, we should pay increasing attention to this problem and take

  16. Estimating renewal timescales with residence time and connectivity in an urban man-made lake in China.

    PubMed

    Gao, Xueping; Xu, Liping; Zhang, Chen

    2016-07-01

    Residence times and connectivity are computed for 12 subregions in an urban man-made lake in China using a high-resolution tracer-transport model. The renewal timescales are explicitly defined and computed for two groups of four freshwater inflow scenarios related to water diversion projects. First, the timescale values are computed and compared using different computational criteria for the upper limit of integration in the residence time equation. The sensitivity analysis suggests that a calculation time of 300 days is necessary to satisfy the relative error (0.001) and 5 % cutoff value criteria. Secondly, the residence times can range from 1.5 to 102 and 1.0 to 66 days under low and high flow conditions, respectively. Water in the inner lake would reside in the lake for less than 66 days prior to exiting the region of interest. The timescale values can be applied to impact studies that investigate the extent of sudden water pollution events that initially affect a subdomain of a lake. Finally, the lacustrine residence times are decomposed into the different subregion residence times, resulting in a connectivity matrix. This matrix can illustrate preferential connections among the individual subregions and reveal hidden patterns relating to local hydrodynamics in the lake.

  17. [Ichthyofauna and its community diversity in volcanic barrier lakes of Northeast China].

    PubMed

    Yang, Fu-Yi; Lü, Xian-Guo; Lou, Yan-Jing; Lou, Xiao-Nan; Xue, Bin; Yao, Shu-Chun; Xiao, Hai-Feng

    2012-12-01

    Based on the investigations of fish resources in Jingpo Lake and Wudalianchi Lakes in 2008-2011 and the historical data, this paper analyzed the characteristics of ichthyofauna and its community diversity in volcanic barrier lakes of Northeast China. The ichthyofauna in the volcanic barrier lakes of Northeast China was consisted of 64 native species, belonging to 47 genera, 16 families, and 9 orders, among which, one species was the second class National protected wild animal, four species were Chinese endemic species, and five species were Chinese vulnerable species. In the 64 recorded species, there were 44 species of Cypriniformes order and 37 species of Cyprinidae family dominated, respectively. The ichthyofauna in the volcanic barrier lakes of Northeast China was formed by 7 fauna complexes, among which, the eastern plain fauna complex was dominant, the common species from the South and the North occupied 53.1%, and the northern endemic species took up 46.9%. The Shannon, Fisher-alpha, Pielou, Margalef, and Simpson indices of the ichthyofauna were 2.078, 4.536, 0.575, 3.723, and 0.269, respectively, and the abundance distribution pattern of native species accorded with lognormal model. The Bray-Curtis, Morisita-Horn, Ochiai, Sørensen, and Whittaker indices between the communities of ichthyofauna in the volcanic barrier lakes of Northeast China and the Jingpo Lake were 0.820, 0.992, 0.870, 0.862 and 0.138, respectively, and those between the communities of ichthyofauna in the volcanic barrier lakes and the Wudalianchi Lakes were 0.210, 0.516, 0.838, 0.825, and 0.175, respectively. The ichthyofauna in volcanic barrier lakes of Northeast China was characterized by the mutual infiltration between the South and the North, and the overlap and transition between the Palaeoarctic realm and the Oricetal realm. It was suggested that the ichthyofauna community species diversity in the volcanic barrier lakes of Northeast China was higher, the species structure was more

  18. Direct versus indirect climate controls on Holocene diatom assemblages in a sub-tropical deep, alpine lake (Lugu Hu, Yunnan, SW China)

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Yang, Xiangdong; Anderson, Nicholas John; Dong, Xuhui

    2016-07-01

    The reconstruction of Holocene environmental changes in lakes on the plateau region of southwest China provides an understanding of how these ecosystems may respond to climate change. Fossil diatom assemblages were investigated from an 11,000-year lake sediment core from a deep, alpine lake (Lugu Hu) in southwest China, an area strongly influenced by the southwest (or the Indian) summer monsoon. Changes in diatom assemblage composition, notably the abundance of the two dominant planktonic species, Cyclotella rhomboideo-elliptica and Cyclostephanos dubius, reflect the effects of climate variability on nutrient dynamics, mediated via thermal stratification (internal nutrient cycling) and catchment-vegetation processes. Statistical analyses of the climate-diatom interactions highlight the strong effect of changing orbitally-induced solar radiation during the Holocene, presumably via its effect on the lake's thermal budget. In a partial redundancy analysis, climate (solar insolation) and proxies reflecting catchment process (pollen percentages, C/N ratio) were the most important drivers of diatom ecological change, showing the strong effects of climate-catchment-vegetation interactions on lake functioning. This diatom record reflects long-term ontogeny of the lake-catchment ecosystem and suggests that climatic changes (both temperature and precipitation) impact lake ecology indirectly through shifts in thermal stratification and catchment nutrient exports.

  19. Regional inequality in China's health care expenditures.

    PubMed

    Chou, Win Lin; Wang, Zijun

    2009-07-01

    This paper has two parts. The first part examines the regional health expenditure inequality in China by testing two hypotheses on health expenditure convergence. Cross-section regressions and cluster analysis are used to study the health expenditure convergence and to identify convergence clusters. We find no single nationwide convergence, only convergence by cluster. In the second part of the paper, we investigate the long-run relationship between health expenditure inequality, income inequality, and provincial government budget deficits (BD) by using new panel co-integration tests with health expenditure data in China's urban and rural areas. We find that the income inequality and real provincial government BD are useful in explaining the disparity in health expenditure prevailing between urban and rural areas. In order to reduce health-spending inequality, one long-run policy suggestion from our findings is for the government to implement more rapid economic development and stronger financing schemes in poorer rural areas.

  20. Plant conservation priorities of Xinjiang region, China

    NASA Astrophysics Data System (ADS)

    Li, L. P.; Cui, W. H.; Wang, T.; Tian, S.; Xing, W. J.; Yin, L. K.; Abdusalih, N.; Jiang, Y. M.

    2017-02-01

    As an important region in the Silk Road, Xinjiang is getting a good chance of developing economy. However at the same time, its natural environment is facing a big challenge. To better protect the plant diversity, it is urgent to make a thorough conservation plan. With a full database of vascular and medicinal plant distributions and nature reserve plant lists and boundaries in Xinjiang of China, we analysed the plant diversity hotspots, protection gaps and proposed the plant conservation priorities of this region. Differed from the widely accepted viewpoints that lots of plants were not included in nature reserves, we found that most of the plants ( > 90%) were actually included in the current nature reserves. We believe that compared with establishing more nature reserves, improving the management of the existing ones is also important. Furthermore, the very few unprotected plants ( < 10%) were distributed mostly in the regions of Aletai, Tacheng, Zhaosu, Manasi, Qitai and Hetian which could be the future conservation priorities.

  1. Roseovarius lacus sp. nov., isolated from Yuncheng Saline Lake, China.

    PubMed

    Pan, Jiafeng; Yu, Zhen; Tang, Jia; Yang, Guiqin; Zhuang, Li; Liu, Zhi; Zhou, Shungui

    2017-03-01

    Strain GSS12(T), a Gram-negative, aerobic, non-flagellated, ovoid- to rod-shaped (0.5-0.7 × 0.9-3.0 µm) bacterium, was isolated from Yuncheng Saline Lake, China. Growth occurred with 0.5-16.0 % (w/v) NaCl (optimum 4.5 %), at pH 5.0-10.0 (optimum pH 6.0-6.5) and at 10-50 °C (optimum 37 °C). The major fatty acids (>5.0 %) found in GSS12(T) were summed feature 8 (72.2 %), C16:0 (9.0 %) and C18:1 ω7c 11-methyl (6.4 %). The DNA G+C content was 62.7 mol%. Analysis of the 16S rRNA gene sequences showed that strain GSS12(T) forms a stable clade with species of the genus Roseovarius, being related to R. pacificus 81-2(T) and R. litoreus GSW-M15(T) with 97.9 and 96.7 % of sequence similarity, respectively. The DNA-DNA relatedness values between strain GSS12(T) and R. pacificus 81-2(T) and R. halotolerans HJ50(T) were low (36 and 29 %, respectively). The phenotypic, physiological, biochemical and genetic characteristics support the assignment of strain GSS12(T) to the genus Roseovarius and represent a novel species. The name Roseovarius lacus sp. nov. is proposed, with strain GSS12(T) (=KCTC 52185(T) =MCCC 1K02302(T)) as the type strain.

  2. Forecasting the spread of invasive rainbow smelt in the Laurentian Great Lakes region of North America.

    PubMed

    Mercado-Silva, Norman; Olden, Julian D; Maxted, Jeffrey T; Hrabik, Thomas R; Vander Zanden, M Jake

    2006-12-01

    Rainbow smelt (Osmerus mordax) have invaded many North American lakes, often resulting in the extirpation of native fish populations. Yet, their invasion is incipient and provides the rationale for identifying ecosystems likely to be invaded and where management and prevention efforts should be focused. To predict smelt presence and absence, we constructed a classification-tree model based on habitat data from 354 lakes in the native range for smelt in southern Maine. Maximum lake depth, lake area, and Secchi depth (surrogate measure of lake productivity) were the most important predictors. We then used our model to identify lakes vulnerable to invasion in three regions outside the smelt's native range: northern Maine (52 of 244 lakes in the non-native range), Ontario (4447 of 8110), and Wisconsin (553 of 5164). We further identified a subset of lakes with a strong potential for impact (potential-impact lakes) based on the presence of fish species that are affected by rainbow smelt. Ninety-four percent of vulnerable lakes in the non-native range in Maine are also potential-impact lakes, as are 94% and 58% of Ontario and Wisconsin's vulnerable lakes, respectively. Our modeling approach can be applied to other invaders and regions to identify invasion-prone ecosystems, thus aiding in the management of invasive species and the efficient allocation of invasive species mitigation and prevention resources.

  3. Evaluation of the WRF-lake model over a highland freshwater lake in southwest China

    NASA Astrophysics Data System (ADS)

    Xu, Lujun; Liu, Huizhi; Du, Qun; Wang, Lei

    2016-12-01

    Evaluation of the Weather Research and Forecasting Model version 3.7.1 lake model performance on lake physical processes and lake-atmosphere interaction at Erhai Lake was conducted with in situ observation data sets over the lake to verify the model results. The lake model with default parameters presented significant negative bias during the day and positive bias during the night on lake surface temperature. Calibrations of water absorption and extinction coefficients, surface roughness length, and eddy diffusion coefficient were carried out to correct this bias. The added absorption and extinction coefficients increased solar radiation in upper water layer, leading to a little higher surface temperature. Compared to constant surface roughness lengths, parameterization of roughness lengths as functions of friction velocity and fetch length significantly improved simulations of lake surface temperature and sensible heat flux. In Erhai Lake, eddy diffusion coefficient of the Henderson-Sellers parameterization is smaller than that in deep lakes. The eddy diffusion coefficient was reduced by a factor of 0.05 in dry season and 0.02 in wet season, respectively, to restrict mixing strength, generating a reasonable diurnal range with observed surface temperature. The adjusted parameter simulations matched better with in situ observations in diurnal cycle of temperature and surface heat fluxes but still overestimated wind speed. Topographic correction is effective to correct the bias, indicating that topographic correction over complex terrain was necessary.

  4. A Systematic Regional-scale Assessment of Lake Dynamics across the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Sheng, Y.; Li, J.; Luo, J.; Kroll, C. N.; Yao, T.; Wu, Y.; Li, X.

    2008-12-01

    The Tibetan Plateau is home to the world's largest high-altitude lake group and has been experiencing significant climate change. Tibetan lakes have been impacted greatly, and in return they serve as a sensitive indicator of regional climate and water cycle variability. The paper provides a regional-scale systematic assessment of both paleo and recent lake changes across the plateau using geo-spatial information technologies. Knowledge of past lake dynamics is essential for us to better understand the current and inferred future lake changes. Since paleo lake shores have been extensively preserved on this remote plateau, paleo lake change since the late Pleistocene (~25 ka BP) can be inferred from paleo shorelines visible in high-resolution satellite imagery with the assistance of digital elevation models. We have recovered the paleo lake extent for more than 650 major contemporary lakes, and found that they have evolved from 173 larger paleo lakes that have shrunk so significantly that more than two-thirds of the original lake area has disappeared. The total water loss due to this lake shrinkage is estimated to be more than 2,900 km3. The recovered paleo lake shrinkage exhibits a strong spatial pattern across the plateau, and corresponds with Quaternary glacial changes in a drainage-basin-based analysis. More recent lake dynamics over the past 30 years can be observed by employing long-archived Landsat satellite data, and only minor changes have been found in most areas. It has been found that glacial dynamics play an important role in detected paleo as well as recent lake changes, and will continue to play a critical role in Tibetan lake dynamics in the near future.

  5. Changes in the Radiocarbon Reservoir Age in Lake Xingyun, Southwestern China during the Holocene

    PubMed Central

    Zhou, Aifeng; He, Yuxin; Wu, Duo; Zhang, Xiaonan; Zhang, Can; Liu, Zhonghui; Yu, Junqing

    2015-01-01

    Chronology is a necessary component of paleoclimatology. Radiocarbon dating plays a central role in determining the ages of geological samples younger than ca. 50 ka BP. However, there are many limitations for its application, including radiocarbon reservoir effects, which may cause incorrect chronology in many lakes. Here we demonstrate temporal changes in the radiocarbon reservoir age of Lake Xingyun, Southwestern China, where radiocarbon ages based on bulk organic matter have been reported in previous studies. Our new radiocarbon ages, determined from terrestrial plant macrofossils suggest that the radiocarbon reservoir age changed from 960 to 2200 years during the last 8500 cal a BP years. These changes to the reservoir effect were associated with inputs from either pre-aged organic carbon or 14C-depleted hard water in Lake Xingyun caused by hydrological change in the lake system. The radiocarbon reservoir age may in return be a good indicator for the carbon source in lake ecosystems and depositional environment. PMID:25815508

  6. Changes in the radiocarbon reservoir age in Lake Xingyun, Southwestern China during the Holocene.

    PubMed

    Zhou, Aifeng; He, Yuxin; Wu, Duo; Zhang, Xiaonan; Zhang, Can; Liu, Zhonghui; Yu, Junqing

    2015-01-01

    Chronology is a necessary component of paleoclimatology. Radiocarbon dating plays a central role in determining the ages of geological samples younger than ca. 50 ka BP. However, there are many limitations for its application, including radiocarbon reservoir effects, which may cause incorrect chronology in many lakes. Here we demonstrate temporal changes in the radiocarbon reservoir age of Lake Xingyun, Southwestern China, where radiocarbon ages based on bulk organic matter have been reported in previous studies. Our new radiocarbon ages, determined from terrestrial plant macrofossils suggest that the radiocarbon reservoir age changed from 960 to 2200 years during the last 8500 cal a BP years. These changes to the reservoir effect were associated with inputs from either pre-aged organic carbon or 14C-depleted hard water in Lake Xingyun caused by hydrological change in the lake system. The radiocarbon reservoir age may in return be a good indicator for the carbon source in lake ecosystems and depositional environment.

  7. Lake-level Fluctuation and Climate Cyclicity Observed in Lake Strata in the Northwestern Qaidam Basin, China

    NASA Astrophysics Data System (ADS)

    Riegel, H. B.; Heermance, R. V., III; Nie, J.; Su, Q.; Garzione, C. N.

    2015-12-01

    The Pliocene and Quaternary are times of rapid, extreme climate variability, but 3-D geologic exposures of lacustrine strata from this time are rare, impeding observations of the impact of climate-change on lake sedimentation. The Qaidam Basin (QB) in western China provides a unique geologic setting, where internally drained lakes have existed for the past few million years, and recent deformation of the basin floor has uplifted and exposed lacustrine strata. This stratigraphy records a detailed history of lake level fluctuation, evaporite deposition, and climate change. We provide new paleomagnetic, δ18O and δ13C data combined with detailed sedimentology from the lower 475 m of a 900 m thick stratigraphic section (38.28N, 91.54E) in the northwestern QB to reveal a high-resolution record of sedimentation and climate change during the Plio-Quaternary. 12 magnetozones indicate an age for the lower half of the section between 6.0-3.0 Ma. The section consists of 9 lithofacies (1 mudstone, 4 sandstone, 1 conglomerate, 2 gypsum, 1 halite) that can be divided into 3 stratigraphic units based on evaporite concentration. Alternating mud, gypsum, and halite beds imply multiple lake-level fluctuations and occasional complete drying of the lake. This is consistent with >12.5‰ variation in the δ18O values of lacustrine carbonates (δ18Oc), indicating large-scale lake level fluctuation below 410 m, consistent with the boundary of Unit 1 and 2. Between 410 and 475 m, the δ18Oc values are ~-5 ‰. Above 475 m, an increase in gypsum concentration causes a thick salt-crust to develop on the outcrop, making sampling impossible. This stratigraphic level corresponds to an age of ~3.0 Ma, when the QB became hyper-arid. The presence of gypsum and halite throughout the section implies that the QB was arid and internally drained by at least 6 Ma, although the basin may have been divided into multiple lakes based on the bimodal δ18O values from different parts of the QB during that

  8. Groundwater contamination by microcystin from toxic cyanobacteria blooms in Lake Chaohu, China.

    PubMed

    Yang, Zhen; Kong, Fanxiang; Zhang, Min

    2016-05-01

    Lake Chaohu is a eutrophic lake that experiences massive cyanobacterial blooms. The high concentrations of microcystin observed in this lake are the result of the bloom's high proportion of toxic cyanobacteria strains. Groundwater is the important source of water for drinking, washing, and irrigation in the watershed of Lake Chaohu. This study examines the space-time distribution of microcystins and related environmental factors in wells near Lake Chaohu. All collected groundwater samples from the Lake Chaohu region had detectable concentrations of microcystins. The highest concentration of microcystins, 1.07 μg L(-1), occurred in a well hundreds of meters from the western coast of the lake in September. The distance from the lake shore to the well was significantly and positively correlated with the microcystin concentration in the groundwater. Moreover, a correlation analysis shows that the microcystin concentration in the groundwater was positively correlated with the total dissolved phosphorus (TDP) and microcystin concentration of the nearby lake water. Therefore, the microcystin in the groundwater likely originates from penetration by nearby lake water. Our results suggest that the groundwater near Lake Chaohu poses a significant health risk for the local residents when used for drinking water.

  9. Relationship between Dongting Lake and surrounding rivers under the operation of the Three Gorges Reservoir, China.

    PubMed

    Zhan, Lucheng; Chen, Jiansheng; Zhang, Shiyin; Huang, Dewen; Li, Ling

    2015-01-01

    The natural flow properties of the Yangtze River have been changed completely following the construction of the Three Gorges Dam. The dam's operation has affected the resources and environment in the middle and lower reaches of the Yangtze River, changing the hydrological conditions and ecological environment of the Dongting Lake. During three different dispatching periods of the reservoir, we took triplicate samples of the river and lake water. All the samples were analysed for δ(2)H and δ(18)O to determine the relationship between the lake and the Yangtze River (and other rivers), and to evaluate objectively the influence of the dam's operation on the lake. During the period of water-supply dispatch, the Four Rivers and Miluo River are the main recharge sources of the lake. During the flood-storage dispatching period, the Dongting Lake is recharged largely by the Three Outlets and the Four Rivers, whereas during the period of water-storage dispatch, most of the lake's water originates from the Miluo, Xiang, Zi, and Yuan rivers. Although the Yangtze River only contributes significantly to the lake's recharge through the Three Outlets during the flood-storage dispatching period, the lake discharges large amounts of water into the Yangtze River during all three periods. Through the operation of the reservoir, it should be ensured that the water level of the Dongting Lake is not too low during the dry season, nor too high during the wet season, thus preventing the lake region from future flood and drought disasters.

  10. 40 CFR 81.67 - Lake Michigan Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Lake Michigan Intrastate Air Quality...) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES Designation of Air Quality Control Regions § 81.67 Lake Michigan Intrastate Air Quality Control Region. The...

  11. Birth Outcomes across Three Rural-Urban Typologies in the Finger Lakes Region of New York

    ERIC Educational Resources Information Center

    Strutz, Kelly L.; Dozier, Ann M.; van Wijngaarden, Edwin; Glantz, J. Christopher

    2012-01-01

    Purpose: The study is a descriptive, population-based analysis of birth outcomes in the New York State Finger Lakes region designed to determine whether perinatal outcomes differed across 3 rural typologies. Methods: Hospital birth data for the Finger Lakes region from 2006 to 2007 were used to identify births classified as low birthweight (LBW),…

  12. Temporary migration and regional development in China.

    PubMed

    Ma, Z

    1999-05-01

    "A new approach to migration in developing countries is used in this paper, which integrates into the migration process the experiences of moving to cities, working in urban areas, and returning to the countryside. As a result, rural labor migration is directly linked to rural development through remittances, as well as through physical and human capital brought back by return migrants. Migration information is mainly drawn from China's 1995 1% National Population Survey.... It has been found that patterns of temporary migration are mainly shaped by the magnetic force of the growth-pole region. Job opportunities created there in labor-intensive industries have attracted large numbers of migrants, first from the surrounding rural areas and then from the peripheral regions, enhancing migration propensity in both areas."

  13. Evaluation of Regional Climate Simulations over the Great Lakes Region Driven by Three Global Data Sets

    SciTech Connect

    Zhong, Shiyuan; Li, Xiuping; Bian, Xindi; Heilman, Warren E.; Leung, Lai-Yung R.; Gustafson, William I.

    2012-06-27

    The performance of regional climate simulations is evaluated for the Great Lakes region. Three 10-year (1990–1999) current-climate simulations are performed using the MM5 regional climate model (RCM) with 36-km horizontal resolution. The simulations employed identical configuration and physical parameterizations, but different lateral boundary conditions and sea-surface temperatures derived from the NCEP Global Reanalysis and output from the CCSM3 and GISS general circulation models (GCMs). The simulation results are compared to the North American Regional Reanalysis (NARR). The three RCM simulations appeared to be more accurate in winter and least accurate in summer, and more accurate aloft than near the surface. The reanalysis-constrained simulation adequately captured the spatial distribution and seasonal cycle of the observed surface-air temperature and precipitation, but it produced consistently across all seasons a cold bias that is generally larger over the lakes than over land and a wet bias due to an overestimation of nonconvective precipitation. The simulated seasonal cycle of moisture–flux convergence over the region was in very good agreement with NARR. The two GCM-driven runs adequately simulated the spatial and seasonal variation of temperature, but overestimated cold-season precipitation and underestimated summer precipitation, reversing the observed annual precipitation cycle. The GISS-driven run failed to simulate the prevailing low-level flow and moisture convergence patterns. All three RCM simulations successfully captured the impact of the Great Lakes on the region's climate, especially on winter precipitation, a significant improvement over coarse-resolution GCM simulations over the region.

  14. Improved AHP method and its application in lake environmental comprehensive quality evaluation—a case study of Xuanwu Lake, Nanjing, China

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Zhang, Hong; Gao, Xiang; Peng, Buzhuo

    2007-10-01

    The relative importance of each pollution factor in analytical hierarchy process (AHP) method comes from pooling expert opinions in general. Because expert opinions are based on information and judgment criteria, determining their weight may lead to uncertainty — Therefore, an improved AHP method had been developed. The process of the improved AHP method involved four key procedures. The weights of pollution factors were completely related to the objective monitoring data through the standardization of these procedures. The environmental comprehensive quality of water and sediment of Xuanwu Lake, Nanjing, China had been evaluated. The environmental quality comprehensive indices (EQCI) of the water in 1991 1995 and 1996 2000 were 3.32 and 1.85, respectively, indicating that the water quality improved. The EQCI of the sediment in 1995 and 2000 indicates that the sediment contamination decreased from 1995 to 2000. Such results agreed with the fact that the lake had been under comprehensive control. However, with the classical AHP method, the EQCI of the sediment in the northwestern part of the lake may have indicated that sediment contamination increased from 1995 to 2000. The discrepancy may have resulted from the judgment difference of the experts. The improved AHP method can avoid arbitrariness of subjective judgment and can reflect the real influential factors of environment pollution in different periods or regions.

  15. Movement patterns of Bar-headed Geese Anser indicus during breeding and post-breeding periods at Qinghai Lake, China

    USGS Publications Warehouse

    Cui, Peng; Hou, Yuansheng; Tang, Mingjie; Zhang, Haiting; Zuohua, Yuanchun; Yin, Zuohua; Li, Tianxian; Guo, Shan; Xing, Zhi; He, Yubang; Prosser, Diann J.; Newman, Scott H.; Takekawa, John Y.; Yan, Baoping; Lei, Fumin

    2011-01-01

    The highly pathogenic avian influenza (HPAI) H5N1 outbreak at Qinghai Lake, China, in 2005 caused the death of over 6,000 migratory birds, half of which were Bar-headed Geese Anser indicus. Understanding the movements of this species may inform monitoring of outbreak risks for HPAI viruses; thus, we investigated the movement patterns of 29 Bar-headed Geese at Qinghai Lake, China during 2007 and 2008 by using high resolution GPS satellite telemetry. We described the movements and distribution of marked Bar-headed Geese during the pre-nesting, nesting, and moulting periods. Of 21 Bar-headed Geese with complete transmission records, 3 moved to other areas during the nesting period: 2 to Jianghe wetland (50 km northwest of Qinghai Lake) and 1 to Cuolongka Lake (220 km northwest of Qinghai Lake) during the nesting period. We identified nesting attempts of 7 of the marked geese at Qinghai Lake. Four completed successful nesting attempts according to our rules of judgment for the breeding status, and 2 geese lost broods soon after hatching (hereafter referred to as unsuccessful breeders). Of 18 geese present at Qinghai Lake during the nesting period, 9 (6 non-breeders, 2 successful breeders and 1 unsuccessful breeder) remained at Qinghai Lake during the moulting period; and 9 (5 non-breeders, 4 unsuccessful breeders) left Qinghai Lake for moulting. Kuhai Lake, Donggeicuona Lake, Alake Lake, Zhaling-Eling Lake area and Huangheyuan wetland area were used as moulting sites. Geese that moulted at Qinghai Lake, Cuolongka Lake, Kuhai Lake, Donggeicuona Lake and Alake Lake also moved to Zhaling-Eling Lake area or Huangheyuan wetland area and stayed there for several days prior to autumn migration. Mean home range and core area estimates did not differ significantly by sex, year and between breeders and non-breeders.

  16. Movement patterns of Bar-headed Geese Anser indicus during breeding and post-breeding periods at Qinghai Lake, China

    USGS Publications Warehouse

    Cui, P.; Hou, Y.; Tang, M.; Zhang, H.; Zhou, Y.; Yin, Z.; Li, T.; Guo, S.; Xing, Z.; He, Y.; Prosser, D.J.; Newman, S.H.; Takekawa, J.Y.; Yan, B.; Lei, F.

    2011-01-01

    The highly pathogenic avian influenza (HPAI) H5N1 outbreak at Qinghai Lake, China, in 2005 caused the death of over 6,000 migratory birds, half of which were Bar-headed Geese Anser indicus. Understanding the movements of this species may inform monitoring of outbreak risks for HPAI viruses; thus, we investigated the movement patterns of 29 Bar-headed Geese at Qinghai Lake, China during 2007 and 2008 by using high resolution GPS satellite telemetry. We described the movements and distribution of marked Bar-headed Geese during the pre-nesting, nesting, and moulting periods. Of 21 Bar-headed Geese with complete transmission records, 3 moved to other areas during the nesting period: 2 to Jianghe wetland (50 km northwest of Qinghai Lake) and 1 to Cuolongka Lake (220 km northwest of Qinghai Lake) during the nesting period. We identified nesting attempts of 7 of the marked geese at Qinghai Lake. Four completed successful nesting attempts according to our rules of judgment for the breeding status, and 2 geese lost broods soon after hatching (hereafter referred to as unsuccessful breeders). Of 18 geese present at Qinghai Lake during the nesting period, 9 (6 non-breeders, 2 successful breeders and 1 unsuccessful breeder) remained at Qinghai Lake during the moulting period; and 9 (5 non-breeders, 4 unsuccessful breeders) left Qinghai Lake for moulting. Kuhai Lake, Donggeicuona Lake, Alake Lake, Zhaling-Eling Lake area and Huangheyuan wetland area were used as moulting sites. Geese that moulted at Qinghai Lake, Cuolongka Lake, Kuhai Lake, Donggeicuona Lake and Alake Lake also moved to Zhaling-Eling Lake area or Huangheyuan wetland area and stayed there for several days prior to autumn migration. Mean home range and core area estimates did not differ significantly by sex, year and between breeders and non-breeders. ?? 2010 Dt. Ornithologen-Gesellschaft e.V.

  17. Developing inorganic carbon-based radiocarbon chronologies for Holocene lake sediments in arid NW China

    NASA Astrophysics Data System (ADS)

    Zhang, Jiawu; Ma, Xueyang; Qiang, Mingrui; Huang, Xiaozhong; Li, Shuang; Guo, Xiaoyan; Henderson, Andrew C. G.; Holmes, Jonathan A.; Chen, Fahu

    2016-07-01

    Inorganic carbonates are often used to establish radiocarbon (14C) chronologies for lake sediments when terrestrial plant remains (TPR) are rare or when bulk organic matter is insufficient for dating, a problem that is common for many lakes in arid regions. However, the reservoir effect (RE), as well as old carbon contributed from the lakes catchment make it difficult to establish reliable chronologies. Here we present a systematic study of inorganic 14C ages of two lake-sediment sequences, one from a small-enclosed saline lake - Lake Gahai in Qaidam Basin, and the other from a large freshwater lake - Lake Bosten in Xinjiang. Modern dissolved inorganic carbon (DIC) of the lakes, paleo-lake sediments exposed in the catchment, and mollusk shells in core sediments from Lake Gahai were dated to assess the RE and the contribution of pre-aged carbon to the old ages in the cores. We propose a statistical regression to assess more than one RE for the 14C carbonate ages within our sedimentary sequences. Old radiocarbon ages contributed by detrital carbonates were assessed by comparing the ages of mollusk shells with those of carbonates at the same sediment depths. We established the RE of the authigenic component and assessed detrital old carbon contributions to our two sites, and this was used to correct the 14C ages. Based on this approach, we developed age models for both cores, and tested them using 210Pb ages in both cores and TPR-based 14C-ages recovered from Lake Bosten. We further tested our age models by comparing carbonate-based oxygen isotope (δ18O) records from both lakes to an independently-dated regional speleothem δ18O record. Our results suggest if sedimentary sequences are densely dated and the RE and the contribution of old carbon from detrital carbonates can be ascertained, robust chronological frameworks based on carbonate-based 14C determinations can be established.

  18. Annual and seasonal streamflow responses to climate and land-cover changes in the Poyang Lake basin, China

    NASA Astrophysics Data System (ADS)

    Guo, Hua; Hu, Qi; Jiang, Tong

    2008-06-01

    SummaryRepeated severe floods and damages in the Poyang Lake basin in China during the 1990s have raised the concern of how the floods have been affected by regional climate variations and by human induced changes in landscape (e.g., draining wetlands around the lake) and land-use in the basin. To address this concern and related issues it is important to know how the climate, land-use and land-cover changes in the region affect the annual and seasonal variations of basin hydrology and streamflow. This knowledge is essential for long-term planning for land-use to protect water resources and to effectively manage floods in the Poyang Lake basin as well as the lower reaches of the Yangtze River. It also has important ecological and socioeconomic implications for the region. This study used the SWAT model to examine the climate and land-use and land-cover effects on hydrology and streamflow in the Xinjiang River basin of the Poyang Lake. A major finding of this study is that the climate effect is dominant in annual streamflow. While land-cover change may have a moderate impact on annual streamflow it strongly influences seasonal streamflow and alters the annual hydrograph of the basin. Because of the vegetation and associated seasonal variations of its impact on evapotranspiration, increase of forest cover after returning agricultural lands to forest reduces wet season streamflow and raises it in dry season, thus reducing flood potentials in the wet season and drought severity in the dry season. On the other hand, losing forests increases flood potential and also enhances drought impacts. Results of this study improve our understanding of hydrological consequences of land-use and climate changes, and provide needed knowledge for effectively developing and managing land-use for sustainability and productivity in the Poyang Lake basin.

  19. Vegetation and climate history in arid western China during MIS2: New insights from pollen and grain-size data of the Balikun Lake, eastern Tien Shan

    NASA Astrophysics Data System (ADS)

    Zhao, Yongtao; An, Cheng-Bang; Mao, Limi; Zhao, Jiaju; Tang, Lingyu; Zhou, Aifeng; Li, Hu; Dong, Weimiao; Duan, Futao; Chen, Fahu

    2015-10-01

    Marine Isotope Stage (MIS) 2 is mostly a cold period encompassing the Last Glacial Maximum (LGM), but the regional expression of MIS2 in arid areas of China is not well known. In this paper, we use high-resolution lacustrine pollen and grain-size records from Balikun Lake to infer vegetation, lake evolution, and climate in arid western China during MIS2. Our results suggest that: 1) the regional vegetation around Balikun was mainly dominated by desert and/or desert-steppe, and Balikun Lake was relatively shallow and experienced high aeolian input during MIS2; 2) distinctive runoff from mountain glacial meltwater in the eastern parts of the Balikun basin caused a high relative abundance of Artemisia pollen during the LGM (26.5-19.2 cal kyr BP), while simultaneously the desert areas expanded as indicated by the high abundance of desert shrubs (e.g., Elaeagnaceae, Rhamnaceae, Hippophae). This cold and dry LGM climate triggered a substantial lowering of lake level; 3) an extremely cold and dry climate prevailing from 17.0 to 15.2 cal kyr BP, correlated with Heinrich event 1 (H1), would explain the low vegetation cover found then; and 4) the warm and humid Bølling/Allerød interstadial (BA: ca. 15-ca. 13 cal kyr BP) is clearly recorded in the Balikun region by the development of wetland herb communities (e.g., Poaceae, Cyperaceae, Typha), and the lake level rose due to increased runoff. Our results challenge the traditional view of cold and wet climatic conditions and high lake levels in arid western China during the LGM, and we propose that changes in local temperature modulated by July insolation was an indispensable factor in triggering vegetation evolution in the Balikun region during MIS2.

  20. How much acidification has occurred in Adirondack region lakes (New York, USA) since preindustrial times

    SciTech Connect

    Cumming, B.F.; Smol, J.P.; Kingston, J.C.; Charles, D.F.; Birks, H.J.B.

    1992-01-01

    Preindustrial and present-day lake water pH, acid neutralizing capacity (ANC), total monomeric aluminum Al(sub m), and dissolved organic carbon (DOC) were inferred from the species composition of diatom and chrysophyte microfossils in the tops (present-day inferences) and bottoms (pre-1850 inferences) of sediment cores collected from a statistically selected set of Adirondack lakes. Results from the study lakes were extrapolated to a predefined target population of 675 low-alkalinity Adirondack region lakes. Estimates of preindustrial to present-day changes in lake water chemistry show that approximately 25-35% of the target population has acidified. The magnitude of acidification was greatest in the low-alkalinity lakes of the southwestern Adirondacks, an area with little geological ability to neutralize acidic deposition and receives the highest annual average rainfall in the region. The authors estimate that approximately 80% of the target population lakes with present-day measured pH = or < 5.2 and 30-45% of lakes with pH between 5.2 and 6.0 have undergone large declines in pH and ANC, and concomitant increases in Al(sub m). Estimated changes in (DOC) were small and show no consistent pattern in the acidified lakes. The study provides the first statistically based regional evaluation of the extent of lake acidification in the Adirondacks.

  1. The Oligochaeta (Annelida, Clitellata) of the St. Lawrence Great Lakes region: An update

    USGS Publications Warehouse

    Spencer, Douglas R.; Hudson, Patrick L.

    2003-01-01

    An updated oligochaete species list for the Great Lakes region is provided. The list was developed through the reexamination of the taxa reported in a previous report in 1980, addition of new taxa or records collected from the region since 1980, and an update of taxonomy commensurate with systematic and nomenclatural changes over the intervening years since the last review. The authors found 74 papers mentioning Great Lakes oligochaete species. The majority of these papers were published in the 1980s. The literature review and additional collections resulted in 15 species being added to the previous list. Nine taxa were removed from the previous list due to misidentification, synonymies, level of identification, or inability to confirm the identity. Based on this review, 101 species of Oligochaeta are now known from the St. Lawrence Great Lakes watershed. Of these, 95 species are known from the St. Lawrence Great Lakes proper, with an additional 6 species recorded from the inland waters of the watershed. The greatest diversity of oligochaete species was found in the inland waters of the region (81) followed by Lake Huron (72), Lake Ontario (65), Lake Erie (64), Lake Superior (63), Lake Michigan (62), St. Marys River (60), Niagara River (49), Saginaw Bay (44), St. Clair River (37), Lake St. Clair (36), St. Lawrence River (27), and the Detroit River (21). Three species are suspected of being introduced, Branchiura sowerbyi, Gianius aquaedulcisand Ripistes parasita, and two are believed to be endemic, Thalassodrilus hallae andTeneridrilus flexus.

  2. "The Effect of Alternative Representations of Lake Temperatures and Ice on WRF Regional Climate Simulations"

    EPA Science Inventory

    Lakes can play a significant role in regional climate, modulating inland extremes in temperature and enhancing precipitation. Representing these effects becomes more important as regional climate modeling (RCM) efforts focus on simulating smaller scales. When using the Weathe...

  3. Temporal 222Rn distributions to reveal groundwater discharge into desert lakes: Implication of water balance in the Badain Jaran Desert, China

    NASA Astrophysics Data System (ADS)

    Luo, Xin; Jiao, Jiu Jimmy; Wang, Xu-sheng; Liu, Kun

    2016-03-01

    How lake systems are maintained and water is balanced in the lake areas in the Badain Jaran Desert (BJD), northeast of China have been debated for about a decade. In this study, continuous 222Rn measurement is used to quantify groundwater discharge into two representative fresh and brine water lakes in the desert using a steady-state mass-balance model. Two empirical equations are used to calculate atmospheric evasion loss crossing the water-air interface of the lakes. Groundwater discharge rates yielded from the radon mass balance model based on the two empirical equations are well correlated and of almost the same values, confirming the validity of the model. The fresh water and brine lakes have a daily averaged groundwater discharge rate of 7.6 ± 1.7 mm d-1 and 6.4 ± 1.8 mm d-1, respectively. The temporal fluctuations of groundwater discharge show similar patterns to those of the lake water level, suggesting that the lakes are recharged from nearby groundwater. Assuming that all the lakes have the same discharge rate as the two studied lakes, total groundwater discharge into all the lakes in the desert is estimated to be 1.59 × 105 m3 d-1. A conceptual model of water balance within a desert lake catchment is proposed to characterize water behaviors within the catchment. This study sheds lights on the water balance in the BJD and is of significance in sustainable regional water resource utilization in such an ecologically fragile area.

  4. Holocene linkages between char, soot, biomass burning and climate from Lake Daihai, China

    NASA Astrophysics Data System (ADS)

    Han, Y. M.; Marlon, J. R.; Cao, J. J.; Jin, Z. D.; An, Z. S.

    2012-12-01

    Black or elemental carbon (EC), including soot and char, are byproducts of anthropogenic fossil-fuel and biomass burning, and also of wildfires. EC, and particularly soot, strongly affects atmospheric chemistry and physics and thus radiative forcing; it can also alter regional climate and precipitation. Pre-industrial variations in EC as well as its source areas and controls however, are poorly known. Here we use a lake-sediment EC record from China to reconstruct Holocene variations in soot (combustion emissions formed via gas-to-particle conversion processes) and char (combustion residues from pyrolysis) measured with a thermal/optical method. Comparisons with sedimentary charcoal records (i.e., particles measured microscopically), climate and population data are used to infer variations in biomass burning and its controls. During the Holocene, positive correlations are observed between EC and an independent index of regional biomass burning. Negative correlations are observed between EC and monsoon intensity, and tree cover inferred from arboreal pollen percentages. Abrupt declines in temperature are also linked with widespread declines in fire. Our results 1) confirm the robustness of a relatively new method for reconstructing variations in EC; 2) document variations in regional biomass burning; 3) support a strong climatic control of biomass burning throughout the Holocene; and 4) indicate that char levels are higher today than at any time during the Holocene.

  5. Dynamical Downscaling over the Great Lakes Basin of North America using the WRF Regional Climate Model: The impact of the Great Lakes system on regional greenhouse warming

    NASA Astrophysics Data System (ADS)

    Gula, J.; Peltier, W. R.

    2011-12-01

    In this study we investigate the regional climate changes to be expected over the Great Lakes Basin of North America during the next century. Large freshwater systems, such as the Great Lakes, play a key role in determining the climate of their basins and adjacent regions by air mass modification through the exchange of heat and moisture with the atmosphere. Even systems as extensive as the Great Lakes are unresolved in coarse resolution global climate simulations but may be accurately captured in finer-mesh regional simulations by dynamical downscaling. Historical (1979-2001) and future (2050-2060 and 2090-2100) conditions are simulated using the Weather Research and Forecasting model (WRF) forced by CCSM3 global simulations. Our analyses are based upon the IPCC SRES A2 and A1B emissions scenarios. A two-step nesting procedure is employed for the purpose of downscaling, in which the first nested WRF model is of North American continental scale at 30 km resolution, whereas the innermost domain at 10 km resolution covers the Great Lakes Basin and the Canadian Province of Ontario. The differences in extreme temperature and precipitation events delivered by the different scales of simulation are discussed. As the WRF model does not currently have an explicit lake component, lake ice and lake surface temperature need to be prescribed in the model. A first set of simulations is performed using climatological 1979-2001) data for lake ice and lake surface temperature. A second set is performed using outputs from the freshwater lake model "FLake" (Mironov, D. V., 2008, COSMO Technical Report, No. 11, Deutscher Wetterdienst, Offenbach am Main, Germany) forced by atmospheric fields from the global simulations. A third set is performed using an interactive coupling of the lake model FLake with the regional model WRF. Changes in surface temperatures and ice cover, and especially ice-out dates, for the Great Lakes under future atmospheric conditions are discussed. The trends in

  6. Heavy Metal Pollution, Fractionation, and Potential Ecological Risks in Sediments from Lake Chaohu (Eastern China) and the Surrounding Rivers.

    PubMed

    Zhang, Lei; Liao, Qianjiahua; Shao, Shiguang; Zhang, Nan; Shen, Qiushi; Liu, Cheng

    2015-11-06

    Heavy metal (Cr, Ni, Cu, Zn, Cd, and Pb) pollution, fractionation, and ecological risks in the sediments of Lake Chaohu (Eastern China), its eleven inflowing rivers and its only outflowing river were studied. An improved BCR (proposed by the European Community Bureau of Reference) sequential extraction procedure was applied to fractionate heavy metals within sediments, a geoaccumulation index was used to assess the extent of heavy metal pollution, and a risk assessment code was applied to evaluate potential ecological risks. Heavy metals in the Shuangqiao and Nanfei Rivers were generally higher than the other studied sites. Of the three Lake Chaohu sites, the highest concentrations were identified in western Chaohu. Heavy metal pollution and ecological risks in the lake's only outflowing river were similar to those in the eastern region of the lake, to which the river is connected. Heavy metal concentrations occurred in the following order: Cd > Zn > Cu > Pb ≈ Ni ≈ Cr. Cr, Ni, and Cu made up the largest proportion of the residual fraction, while Cd was the most prominent metal in the exchangeable and carbonate-included fraction. Cd posed the greatest potential ecological risk; the heavy metals generally posed risks in the following order: Cd > Zn > Cu > Ni > Pb > Cr.

  7. Spatiotemporal patterns and ecophysiology of toxigenic microcystis blooms in Lake Taihu, China: implications for water quality management.

    PubMed

    Otten, T G; Xu, H; Qin, B; Zhu, G; Paerl, H W

    2012-03-20

    Whole lake monitoring of hypertrophic Lake Taihu, China, was conducted during the summers of 2009-2010, with the intent of identifying environmental factors influencing Microcystis bloom formation and promoting the growth of toxigenic strains (mcyE possessing). Low N:P ratios (replete N & P)appeared to select for toxigenic populations of Microcystis spp., whereas nontoxic Microcystis spp. strains were dominant in more nutrient limited regions of the lake. Chlorophyll a (Adj. R(2) = 0.83, p < 0.0001) was equally predicative of microcystin variance across the lake as fluorescence based real-time quantitative PCR (qPCR) measurements of microcystin synthetase E (mcyE) gene equivalents (Adj. R(2) = 0.85, p < 0.0001). Interestingly, chlorophyll a was identified as a more robust and useful metric for predicting microcystin concentrations than qPCR measurements enumerating the total Microcystis population based on c-phycocyanin (α subunit; cpcA) gene equivalents (Adj. R(2) = 0.61, p < 0.0001). Overall, the lakewide composition of Microcystis spp. was highly variable over time and space, and on average the population consisted of 36 ± 12% potentially toxic cells. On the basis of this study's findings, a framework for the design and implementation of a water safety plan for Taihu water quality managers and public health officials is proposed.

  8. A coupled regional climate model for the Lake Victoria basin of East Africa

    NASA Astrophysics Data System (ADS)

    Song, Yi; Semazzi, Fredrick H. M.; Xie, Lian; Ogallo, Laban J.

    2004-01-01

    A nested coupled model has been developed to investigate the two-way interactions between the regional climate of eastern Africa and Lake Victoria. The atmospheric component of the model is the North Carolina State University (NCSU) version of the National Center for Atmospheric Research (NCAR) regional climate model (NCSU-RegCM2). The lake component of the model is based on the Princeton ocean model (POM).Three simulations, each 4 months long, have been performed for the short rains of eastern Africa of September through to December. The control experiment is based on the standard NCSU-RegCM2 model coupled to a one-dimensional model of Lake Victoria. The second experiment was based on the stand-alone three-dimensional primitive equation POM-Lake Victoria model forced by output from the atmospheric component of the control run. The third experiment is based on the integration of the coupled system of the NCSU-RegCM2 model where the one-dimensional lake model in the control run has been replaced by the three-dimensional POM hydrodynamical model for Lake Victoria.The results confirm that adopting the traditional modelling approach, in which the lake hydrodynamics are neglected and the formulation is based entirely on thermodynamics alone, is not entirely satisfactory for the Lake Victoria basin. Such a strategy precludes the transport of heat realistically within the lake, from the heat surplus regions to the cooler regions, and thereby results in a degraded simulation of the climate downstream over the rest of the lake and the surrounding land regions. The numerical simulations show that the southwestern region of the lake is an important source of warm water because it is relatively shallower and the water column is heated up much more quickly during the day than the rest of the lake. The result is that the surface temperature anomaly field from the all-lake area average consists of a gradient pattern with warmer water over the shallow region of the lake over the

  9. Viral metagenomics analysis of planktonic viruses in East Lake, Wuhan, China.

    PubMed

    Ge, Xingyi; Wu, Yongquan; Wang, Meiniang; Wang, Jun; Wu, Lijun; Yang, Xinglou; Zhang, Yuji; Shi, Zhengli

    2013-10-01

    East Lake (Lake Donghu), located in Wuhan, China, is a typical city freshwater lake that has been experiencing eutrophic conditions and algal blooming during recent years. Marine and fresh water are considered to contain a large number of viruses. However, little is known about their genetic diversity because of the limited techniques for culturing viruses. In this study, we conducted a viral metagenomic analysis using a high-throughput sequencing technique with samples collected from East Lake in Spring, Summer, Autumn, and Winter. The libraries from four samples each generated 234,669, 71,837, 12,820, and 34,236 contigs (> 90 bp each), respectively. The genetic structure of the viral community revealed a high genetic diversity covering 23 viral families, with the majority of contigs homologous to DNA viruses, including members of Myoviridae, Podoviridae, Siphoviridae, Phycodnaviridae, and Microviridae, which infect bacteria or algae, and members of Circoviridae, which infect invertebrates and vertebrates. The highest viral genetic diversity occurred in samples collected in August, then December and June, and the least diversity in March. Most contigs have low-sequence identities with known viruses. PCR detection targeting the conserved sequences of genes (g20, psbA, psbD, and DNApol) of cyanophages further confirmed that there are novel cyanophages in the East Lake. Our viral metagenomic data provide the first preliminary understanding of the virome in one freshwater lake in China and would be helpful for novel virus discovery and the control of algal blooming in the future.

  10. Wolves in the Great Lakes region: a phylogeographic puzzle.

    PubMed

    Randi, Ettore

    2010-10-01

    Empirical studies demonstrate that natural hybridization in animals is more common than thought so far (Mallet 2005), particularly among species that originated recently through cycles of population contraction-expansion arising from climate changes over the last glacial period, the Pleistocene. In addition, the post-glacial global growth of human populations has fostered anthropogenic hybridization events, mediated by habitat changes, the persecution of large predators and the introduction of alien species (Allendorf et al. 2001). The Canis lineage shows cases of both natural and anthropogenic hybridization, exacerbating the controversy about the number of species that should be formally validated in the taxonomic lists, the evolutionary role of genetic introgression and the ways to manage hybrids with invading wild or domesticated populations. The study by Wheeldon et al. (2010), published in this issue of Molecular Ecology, adds a new piece to the intricate puzzle of evolution and taxonomy of Canis in North America. They show that sympatric wolves (C. lupus) and coyotes (C. latrans) are not (extensively) hybridizing in the western North American Great Lakes region (GLR). Widespread hybridization between coyotes and a genetically distinct, but closely related, wolf-like population (the eastern wolf) occurred in the northeastern regions of North America. In Wheeldon et al.'s (2010) opinion, these data should prove definitely that two different species of wolf (the western gray wolf C. lupus and the eastern wolf C. lycaon) and their hybrids are distributed across the GLR.

  11. Changes in discharge dynamics under the constraints of local and global changes in the Chao Lake basin (China)

    NASA Astrophysics Data System (ADS)

    Chu, Y.; Salles, C.; Rodier, C.; Crès, F.-N.; Huang, L.; Tournoud, M.-G.

    2012-04-01

    Located on the Yangtze basin, the Chao Lake is the fifth largest freshwater lake in China and of great importance in terms of water resources and aquaculture. Its catchment (9130 km2) includes the city of Hefei and large extends of agricultural and rural areas. Fast changes are expected in land uses and agricultural practices for the future, due to the touristic appeal of the Chao Lake shore and the growth of the city of Hefei. Climate changes are also expected in this region, with a high impact on rainfall regime. The consequences of these changes on the sustainability of the water inflows into the lake are a major issue for the economical development of the Chao Lake area even though they are little-known. Our study aims to give tools for estimating such consequences, accounting for uncertainties in scenario data and model parameters. The dynamics of rivers flowing into the Chao Lake is not very well-known, except for the Fengle River. The Fengle catchment (1480 km2) is mainly rural. River discharges are recorded at Taoxi station, upstream its outlet into the lake. 20-year records of daily discharges are available. Nine rain gauges, with daily data, daily temperature and evapotranspiration data are also available. The current dynamics of the Fengle River is characterized in terms of flood frequencies on discharge-duration-frequency curves. The ATHYS freely available hydrological tool (www.athys-soft.org) is used to calibrate and validate a distributed model of the Fengle catchment. Four calibration runs are done on four independent 5-year discharge records. Four different sets of model parameters are discussed. The model is then run for validation. The uncertainties in model predictions are evaluated in terms of errors in the simulated discharges during the validation period, with regards to the 5-year period used for calibration. The model is then applied on scenarios of changes in land uses and climate. Uncertainties in scenarios of changes are estimated

  12. Seismic reflection study of recessional moraines beneath Lake Superior and their relationship to regional deglaciation

    USGS Publications Warehouse

    Landmesser, C.W.; Johnson, T.C.; Wold, R.J.

    1982-01-01

    Approximately 8000 km of continuous seismic reflection profiles throughout Lake Superior were examined for evidence of recessional moraines and other ice-margin deposits associated with the retreat of late Wisconsin ice. These features are correlated with the record of glacial-lake evolution in western Lake Superior. An offlapping sequence of glacial and glacial-lacustrine dediments overlying bedrock is recognized in west-central Lake Superior that is progressively younger to the northeast. The sequence underlies more recent glaical-lacustrine and postglacial sediments. Four facies are recognized on the basis of geomorphologic and acoustic properties and are interpreted to represent a southwest-to-northeast assemblage of: proglacial stratified drift (facies A), drift in major end moraines (facies B), till deposited as glacial retreat resumed, or possibly late-stage ablation till (facies C), and basal till (facies D). The prominent moraines of facies B are unusually thick and are believed to mark the ice-margin shorelines of successive major proglacial lakes that formerly occupied parts of western Lake Superior. The moraines are tentatively correlated with Glacial Lake Duluth (unit 1), Glacial Lake Washburn (unit 2), and Glacial Lake Beaver Bay (unit 3), the most prominent of lakes drained via the progressively lower outlets via the Moose Lake/ Brule-St. Croix Rivers, the Huron Mountains, and the Au Train-Whitefish regions, respectively. ?? 1982.

  13. Sensitivity of lake ice regimes to climate change in the Nordic region

    NASA Astrophysics Data System (ADS)

    Gebre, S.; Boissy, T.; Alfredsen, K.

    2014-08-01

    A one-dimensional process-based multi-year lake ice model, MyLake, was used to simulate lake ice phenology and annual maximum lake ice thickness for the Nordic region comprising Fennoscandia and the Baltic countries. The model was first tested and validated using observational meteorological forcing on a candidate lake (Lake Atnsjøen) and using downscaled ERA-40 reanalysis data set. To simulate ice conditions for the contemporary period of 1961-2000, the model was driven by gridded meteorological forcings from ERA-40 global reanalysis data downscaled to a 25 km resolution using the Rossby Centre Regional Climate Model (RCA). The model was then forced with two future climate scenarios from the RCA driven by two different general circulation models (GCMs) based on the Special Report on Emissions Scenarios (SRES) A1B. The two climate scenarios correspond to two future time periods namely the 2050s (2041-2070) and the 2080s (2071-2100). To take into account the influence of lake morphometry, simulations were carried out for four different hypothetical lake depths (5 m, 10 m, 20 m, 40 m) placed at each of the 3708 grid cells. Based on a comparison of the mean predictions in the future 30-year periods with the control (1961-1990) period, ice cover durations in the region will be shortened by 1 to 11 weeks in 2041-2070, and 3 to 14 weeks in 2071-2100. Annual maximum lake ice thickness, on the other hand, will be reduced by a margin of up to 60 cm by 2041-2070 and up to 70 cm by 2071-2100. The simulated changes in lake ice characteristics revealed that the changes are less dependent on lake depths though there are slight differences. The results of this study provide a regional perspective of anticipated changes in lake ice regimes due to climate warming across the study area by the middle and end of this century.

  14. HISTORICAL SNOW AMOUNTS IN THE LAKE EFFECT REGION OF LAKE SUPERIOR: EVIDENCE OF CLIMATE CHANGE IN THE GREAT LAKES

    EPA Science Inventory

    Recent studies (Levitus et al., .2000) suggest a warming of the world ocean over the past 50 years. This could be occurring in the Great Lakes also but thermal measurements are lacking. Historical trends in natural phenomena, such as the duration of ice cover on lakes, provide in...

  15. Water pollution and cyanobacteria's variation of rivers surrounding southern Taihu Lake, China.

    PubMed

    Sun, Mingyang; Huang, Linglin; Tan, Lisha; Yang, Zhe; Baig, Shams Ali; Sheng, Tiantian; Zhu, Hong; Xu, Xinhua

    2013-05-01

    The water quality and cyanobacterial variation of rivers surrounding southern Taihu Lake, China were purposively monitored from 2008 to 2010. Trophic level index (TLI) was used to evaluate the trophic levels of southern Taihu Lake. Results showed a considerable decline in the monitored data compared with 2007, and the data showed downward trends year after year. The TLI decreased from 55.6 to 51.3, which implied that southern Taihu Lake was mildly eutrophic. The water quality and cyanobacterial variation indicated a positive response to the adopted control measures in the southern Taihu Lake basin, but the intra- and inter-annual variability was still quite varied. High concentrations of nitrogen and phosphorus typically lead to algae outbreaks, however, the cyanobacteria growth may result in a decline of the concentration of nitrogen and phosphorus. Temperature and other weather conditions are also important factors for algae outbreaks; the risk of blue-green algal blooms still persists.

  16. The Change Analysis of Wetland Landscape Based on Remote Sensing Data in Dongting Lake, China

    NASA Astrophysics Data System (ADS)

    Huang, Qun; Jiang, Jiahu; Yesou, Herve; Lai, Xijun

    2013-01-01

    Wetlands have very important ecological and service functions for human beings. However, the changing hydrological conditions and basins may result in the evolution of a wetland ecosystem. Understanding the knowledge of wetland changes can help us to conserve them. As an increasing abundant data sources, remote sensing data have their specific advantages for large scale analysis for wetland landscape. Dongting Lake is the second largest freshwater lake in China of an international importance for winterbirds and other important values. Here, the changes of wetland landscape were investigated based on optical remote sensing images from 1989 to 2010. The landscape types are classified four types consisting of open water, mudflats, lake grasses and reeds. During the past 20 years, the pattern of wetland landscape has changed rapidly. The area of reeds showed a steady increase with a growth rate of 13.1km2 per year. It increased from 475 km2 in 1989 to 751 km2 in 2010. The distribution area of lake grass kept stable but with slight fluctuation. The distribution area of water and mudflats has significantly reduced in near years. Generally, the evolution of landscape pattern in Dongting Lake shows the tendency of the extrusion of reeds into lake grasses and lake grasses into open water and mudflats.

  17. Antibiotic resistance genes in lakes from middle and lower reaches of the Yangtze River, China: Effect of land use and sediment characteristics.

    PubMed

    Yang, Yuyi; Liu, Wenzhi; Xu, Chen; Wei, Buqing; Wang, Jun

    2017-07-01

    Freshwater lakes provided an ideal media for the accumulation and propagation of antibiotic resistance genes (ARGs), because they were susceptible to anthropogenic impacts. Land reclamation and urbanization exerted severe anthropogenic impacts on lakes from middle and lower reaches of the Yangtze River, China over the past decades. In this study, 15 lakes in the region were selected to understand the level and variability of ARGs. Proportion of different land use types was applied to display the land reclamation and urbanization around each lake. For sulfonamide resistance (sul) genes, sul1 had the highest relative abundance in sediments, with maximum 2.11 × 10(-1) copies/16SrRNA copy in Gehu Lake. For tetracycline resistance (tet) genes, tetG had the highest average value of relative abundance (4.74 × 10(-3) copies/16SrRNA copy), followed by tetB, tetA, tetQ and tetM. Class I integron (intI1) played an important role in acquisition and dissemination of sul1 and tetG. Sediment characteristics (moisture, density, total nitrogen, total carbon, ammonium, and nitrate) were found to have no significant effect on ARG distribution. Taihu Lake and Yangcheng Lake which exhibited high sul and tet genes had the high proportion of built-up land use.

  18. Stable carbon isotope of black carbon in lake sediments as an indicator of terrestrial environmental changes: an evaluation on paleorecord from Daihai Lake, Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Cui, L.; Wang, X.

    2012-12-01

    We measured the carbon isotope ratio of black carbon (BC) from the Daihai Lake sediment core (DH99a) in north-central China with an objective to examine the effectiveness and sensitivity of the δ13C values of BC (δ13CBC) as a potential indicator of terrestrial environmental changes. We first performed a statistical study on the available data regarding carbon isotope fractionation (CIF) during the conversion of C3 and C4 vegetation to BC and observed that the mean CIF for BC produced from C3 plants is -0.2‰, whereas that for BC from C4 plants is -1.5‰. This result provides a solid reference for reconstructing vegetation and environmental changes using the δ13CBC values. The δ13CBC record in the DH99a sediment core spanning the last ca 10,000 years displayed large variations from -23.69‰ to -29.18‰, which suggests that C3 plants dominantly occupied the Daihai Lake region during the Holocene. The most negative δ13CBC peaks coincided with high values of tree percentages and grain sizes, which occurred under relatively wetter climatic conditions during the middle Holocene (ca 6500-3200 cal. yr BP) and an interval between 1700 and 1350 cal. yr BP. In contrast, the least negative δ13CBC values corresponded to low values of tree percentages and grain sizes during relatively drier phases of the early and late Holocene. The negative correlation of the δ13CBC values with the tree percentages and grain sizes was thought to reflect a negative correlation of the δ13CBC values with the monsoon precipitation. This correlation is consistent with the response of carbon isotope in modern C3 plants to precipitation in north China. Therefore, we developed a computational model to reconstruct the changes in annual precipitation over the Daihai Lake region using the δ13CBC values. The results indicated that the annual precipitation was highly variable, ranging from 220 mm lower to 280 mm higher than present during the middle Holocene, whereas the annual precipitation

  19. Sediment distribution pattern mapped from the combination of objective analysis and geostatistics in the large shallow Taihu Lake, China.

    PubMed

    Luo, Lian-Cong; Qin, Bo-Qiang; Zhu, Guang-Wei

    2004-01-01

    Investigation was made into sediment depth at 723 irregularly scattered measurement points which cover all the regions in Taihu Lake, China. The combination of successive correction scheme and geostatistical method was used to get all the values of recent sediment thickness at the 69 x 69 grids in the whole lake. The results showed that there is the significant difference in sediment depth between the eastern area and the western region, and most of the sediments are located in the western shore-line and northern regimes but just a little in the center and eastern parts. The notable exception is the patch between the center and Xishan Island where the maximum sediment depth is more than 4.0 m. This sediment distribution pattern is more than likely related to the current circulation pattern induced by the prevailing wind-forcing in Taihu Lake. The numerical simulation of hydrodynamics can strong support the conclusion. Sediment effects on water quality was also studied and the results showed that the concentrations of TP, TN and SS in the western part are obviously larger than those in the eastern regime, which suggested that more nutrients can be released from thicker sediment areas.

  20. Recruitment of Total Phytoplankton, Chlorophytes and Cyanobacteria from Lake Sediments Recorded by Photosynthetic Pigments in a Large, Shallow Lake (Lake Taihu, China)

    NASA Astrophysics Data System (ADS)

    Cao, Huan-Sheng; Kong, Fan-Xiang; Tan, Jian-Kang; Zhang, Xiao-Feng; Tao, Yi; Yang, Zhou

    2005-08-01

    Recruitment of total phytoplankton, chlorophytes and cyanobacteria from lake sediments to the water column was studied using photosynthetic pigments at one site (1.5 m) in Lake Taihu, a large shallow lake in China. Samples were taken weekly from the migration traps installed on the bottom from March to May 2004. Abundance of total phytoplankton, chlorophytes and cyanobacteria were represented by Chlorophyll (Chl) a, b, and phycocyanin (PC), respectively. Over the three months, total phytoplankton, chlorophytes, and cyanobacteria corresponding to 48.9%, 68.9% and 316.2% of their initial concentrations in surface sediments were recruited in Lake Taihu. However, compared with their increase in pelagic abundance over the same period, the recruitment accounted for a rather small inoculum. Accompanying the recruitment, total phytoplankton and chlorophytes declined and cyanobacteria increased in the upper 0-2 cm sediments; colonies of Microcystis aeruginosa in the water column enlarged from small size with several cells to large colonies with hundreds of cells. Thus, overwintering and subsequent growth renewal of pelagic phytoplankton merits further study and comparison with benthic survival and recruitment.

  1. The mesoproterozoic midcontinent rift system, Lake Superior region, USA

    USGS Publications Warehouse

    Ojakangas, R.W.; Morey, G.B.; Green, J.C.

    2001-01-01

    Exposures in the Lake Superior region, and associated geophysical evidence, show that a 2000 km-long rift system developed within the North American craton ??? 1109-1087 Ma, the age span of the most of the volcanic rocks. This system is characterized by immense volumes of mafic igneous rocks, mostly subaerial plateau basalts, generated in two major pulses largely by a hot mantle plume. A new ocean basin was nearly formed before rifting ceased, perhaps due to the remote effect of the Grenville continental collision to the east. Broad sagging/subsidence, combined with a system of axial half-grabens separated along the length of the rift by accommodation zones, provided conditions for the accumulation of as much as 20 km of volcanic rocks and as much as 10 km of post-rift clastic sediments, both along the rift axis and in basins flanking a central, post-volcanic horst. Pre-rift mature, quartzose sandstones imply little or no uplift prior to the onset of rift volcanism. Early post-rift red-bed sediments consist almost entirely of intrabasinally derived volcanic sediment deposited in alluvial fan to fluvial settings; the exception is one gray to black carbon-bearing lacustrine(?) unit. This early sedimentation phase was followed by broad crustal sagging and deposition of progressively more mature red-bed, fluvial sediments with an extra-basinal provenance. ?? 2001 Elsevier Science B.V. All rights reserved.

  2. ANALYSIS OF MERCURY IN VERMONT AND NEW HAMPSHIRE LAKES: EVALUATION OF THE REGIONAL MERCURY CYCLING MODEL

    EPA Science Inventory

    An evaluation of the Regional Mercury Cycling Model (R-MCM, a steady-state fate and transport model used to simulate mercury concentrations in lakes) is presented based on its application to a series of 91 lakes in Vermont and New Hampshire. Visual and statistical analyses are pr...

  3. 2016 Federal Green Challenge Award Winners in the Great Lakes Region

    EPA Pesticide Factsheets

    2016 FGC award winners in the Great Lakes region: Mpls. Veterans Affairs (VA) Healthcare System, MN National Guard, U.S. EPA Mid-Continent Ecology Division, U.S. Customs and Border Protection Detroit Field Office, and Naval Station Great Lakes.

  4. Regional climate signal modified by local factors - multi core study records (Lake Czechowskie region, N Poland)

    NASA Astrophysics Data System (ADS)

    Zawiska, Izabela; Rzodkiewicz, Monika; Noryśkiewicz, Agnieszka; Kramkowski, Mateusz; Obremska, Milena; Ott, Florian; Plessen, Birgit; Tjallingii, Rik; Słowiński, Michał; Błaszkiewicz, Mirosław; Brauer, Achim

    2016-04-01

    Lake sediments can be utilized as valuable paleoclimate and environmental archives as they contain information of past changes. Multi-proxy analyses of sedimentary compartments (e.g. pollen, diatoms, Cladocera) reveal those changes. However, to decipher the spatial variability of past climate changes and to define the proxies suited for local and regional scale reconstructions archive comparisons are needed. Here we present a detailed multi-proxy study from four different sediment cores covering the Younger Dryas cold period from the Lake Czechowskie region (N Poland). Three cores are located along a transect in the Lake Czechowskie basin from its deepest point towards a former lake bay close to today's shoreline. The fourth lacustrine sediment core was retrieved from the Trzechowskie paleolake, app. 1 km W from Lake Czechowskie. The dataset comprises information from pollen (AP, NAP, Juniperus, Betula-tree, Pinus silvestris), diatom (planktonic/benthic index, diatom valve concentration, dominant species), Cladocera (planktonic/benthic index, dominant species, number of Cladocera species, total sum of specimens) and geochemical (TOC and CaCO3 content, mineral matter, titanium) analyses. At the beginning of the Younger Dryas the AP pollen share decreased and NAP and Juniperus pollen increased in all studied locations. The mineral matter and titanium record showed higher values in two cores taken from the deepest parts of Lake Czechowskie and the core from Trzechowskie paleolake while in the core located at the marginal part of the lake it was already high in Allerød and it did not change much in Younger Dryas. The Cladocera based indexes: total sum of specimens and number of species decreased at the beginning of YD but on the contrary the Cladocera species composition changes were site-specific. The diatoms valve concentration index significantly lowered in core from the deep location while on the contrary increased in core from paleolake Trzechowskie. Our results

  5. ASTER measurement of supraglacial lakes in the Mount Everest region of the Himalaya

    USGS Publications Warehouse

    Wessels, R.L.; Kargel, J.S.; Kieffer, H.H.

    2002-01-01

    We demonstrate an application of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images to detect and monitor supraglacial lakes on glaciers in the Mount Everest region in Tibet (Xizang) and Nepal. ASTER offers powerful capabilities to monitor supraglacial lakes in terms of (1) surface area, growth and disappearance (spatial resolution = 15 m), (2) turbidity (15 m resolution), and (3) temperature (90 m resolution). Preliminary results show an overall similarity of supraglacial lakes on three glaciers. Lakes have widely varying turbidity as indicated by color in visible/near-infrared bands 1-3, the largest lakes being bright blue (highly turbid), cold (near 0??C) and hydrautically connected with other lakes and supraglacial streams, while small lakes are mostly dark blue (relatively clear water), warmer (>4??C), and appear hydrautically isolated. High levels of turbidity in supraglacial lakes indicate high rates of meltwater input from streams or erosion of ice cliffs, and thus are an indirect measure relating to the activity and hydraulic integration of the lake with respect to other lakes and streams in the glacier.

  6. The Penokean orogeny in the Lake Superior region

    USGS Publications Warehouse

    Schulz, K.J.; Cannon, W.F.

    2007-01-01

    period of vertical faulting in the Archean basement and overlying Paleoproterozoic strata. This deformation is now known to have post-dated the terminal Penokean plutons by at least several tens of millions of years. Evidence of the Penokean orogen is now largely confined to the Lake Superior region. Comparisons with more recent orogens formed by similar plate tectonic processes implies that significant parts of a once more extensive Penokean orogen have been removed or overprinted by younger tectonic events. ?? 2007 Elsevier B.V. All rights reserved.

  7. Distribution, source characterization and inventory of perfluoroalkyl substances in Taihu Lake, China.

    PubMed

    Guo, Changsheng; Zhang, Yuan; Zhao, Xin; Du, Ping; Liu, Sisi; Lv, Jiapei; Xu, Fengxia; Meng, Wei; Xu, Jian

    2015-05-01

    The levels, distribution, possible sources, and inventory of perfluoroalkyl acids (PFAAs) in the eutrophic freshwater Taihu Lake, East China were investigated in this study. Among the target 11 PFAAs, perfluorooctanoic acid (PFOA) (2.15-73.9 ng L(-1)) and perfluorohexanoic acid (PFHxA) (region, and the inventory of ΣPFCA and PFOS were estimated to be 989 kg and 646 kg in Taihu Lake.

  8. Landscape ecological assessment and eco-tourism development in the South Dongting Lake Wetland, China.

    PubMed

    He, Ping; Wang, Bao-zhong

    2003-03-01

    As an important resource and the living environment of mankind, wetland has become gradually a highlight, strongly concerned and intensively studied by scientists and sociologists. The governments in the world and the whole society have been paying more and more attention on it. The Dongting Lake of China is regarded as an internationally important wetland. For a rational development and protection of the wetland, an investigation and studied on its resources and its value to tourism in the South Dongting Lake was conducted, to create an assessment system of the ecological landscapes, and to evaluate qualitatively and quantitatively the value of wetland landscape to the ecotourism. The results showed that the scenic value of the South Dongting Lake Wetland satisfied the criterion of AAAA grade of China national scenic attraction. The eco-tourism value of the landscape cultures in the South Dongting Lake Wetland was discussed with emphasis. It were formulated that a principle and frame of sustainable exploitation of the wetland landscapes and it was proposed as well that establishing a Wetland Park and developing eco-tourism in the South Dongting Lake Wetland is a fragile ecosystem with low resistance to the impact of the exploitation. Thus, we must pay intensively attention to the influence of exploitation on the landscape, take the ecological risk in account to employ a right countermeasure and avoid the negative affection.

  9. Geological record of meltwater events at Qinghai Lake, China from the past 40 ka

    NASA Astrophysics Data System (ADS)

    Zhou, Weijian; Liu, Taibei; Wang, Hao; An, Zhisheng; Cheng, Peng; Zhu, Yizhi; Burr, G. S.

    2016-10-01

    We report here on a previously unpublished sediment core from Qinghai Lake, China, that preserves a continuous record of sedimentation for the past 40 ka. A striking feature of the record is a set of distinct meltwater events recorded at 35, 19 and 14 ka respectively. These events are manifest as distinct pulses of relatively old organic radiocarbon in the sediments. We interpret these as a signal of glacial melting in the Qinghai Lake watershed. The meltwater signals are closely correlated to temperature and precipitation records associated with deglaciation. The events at 19 ka and 14 ka correspond to well-established high latitude Melt Water Pulse (MWP) events during Marine Isotope Stage (MIS) 2, and the 35 ka event corresponds to a period of pervasive high lake levels in western China during late MIS 3. We interpret these anomalous dates as the result of relatively old carbon that was destabilized by the glaciers, and released into the lake as the glaciers melted. The data indicate that this process takes thousands of years. We expect that the approach employed here to identify these events is generally applicable to any lake system with a significant glacial meltwater component.

  10. Cyanobacteria in lakes on Yungui Plateau, China are assembled via niche processes driven by water physicochemical property, lake morphology and watershed land-use

    NASA Astrophysics Data System (ADS)

    Liao, Jingqiu; Zhao, Lei; Cao, Xiaofeng; Sun, Jinhua; Gao, Zhe; Wang, Jie; Jiang, Dalin; Fan, Hao; Huang, Yi

    2016-11-01

    Plateau lakes are important ecosystems with diverse ecological functions. Cyanobacteria play a key role in plateau lakes as primary producers. However, they are threatening when dense blooms occur. Identifying cyanobacteiral biogeography and the mechanism of assembly processes shaping the distribution of cyanobacteria in plateau lakes is critical for understanding cyanobacterial ecology and applying it to lake management. In the present study, the biogeographic pattern and importance of neutral and niche processes in assembly of cyanobacteria in 21 lakes on Yungui Plateau, China were examined. Results showed that cyanobacteria exhibit unique biogeographic pattern, and most of them have a narrow habitat preference in plateau lakes. They were assembled via niche processes driven by water physicochemical property, lake morphology and watershed land-use, which explained 62.4% of the biological variation. Neutral processes were not at play. Water physicochemical property (key variables - dissolved oxygen, salinity, trophic status and pH) was the most dominant driver shaping its unique biogeographic pattern. Watershed land-use especially urban land, water body and agricultural land also exhibited a strong impact on cyanobacterial distribution, followed by lake morphology. As most of the cyanobacteiral genus detected in these plateau lakes were potential toxin-producers, this study indicated that in order to protect waters from toxic-bloom in the future, reducing nutrient loading and land-use practices are two practical approaches in plateau lake management.

  11. Cyanobacteria in lakes on Yungui Plateau, China are assembled via niche processes driven by water physicochemical property, lake morphology and watershed land-use

    PubMed Central

    Liao, Jingqiu; Zhao, Lei; Cao, Xiaofeng; Sun, Jinhua; Gao, Zhe; Wang, Jie; Jiang, Dalin; Fan, Hao; Huang, Yi

    2016-01-01

    Plateau lakes are important ecosystems with diverse ecological functions. Cyanobacteria play a key role in plateau lakes as primary producers. However, they are threatening when dense blooms occur. Identifying cyanobacteiral biogeography and the mechanism of assembly processes shaping the distribution of cyanobacteria in plateau lakes is critical for understanding cyanobacterial ecology and applying it to lake management. In the present study, the biogeographic pattern and importance of neutral and niche processes in assembly of cyanobacteria in 21 lakes on Yungui Plateau, China were examined. Results showed that cyanobacteria exhibit unique biogeographic pattern, and most of them have a narrow habitat preference in plateau lakes. They were assembled via niche processes driven by water physicochemical property, lake morphology and watershed land-use, which explained 62.4% of the biological variation. Neutral processes were not at play. Water physicochemical property (key variables - dissolved oxygen, salinity, trophic status and pH) was the most dominant driver shaping its unique biogeographic pattern. Watershed land-use especially urban land, water body and agricultural land also exhibited a strong impact on cyanobacterial distribution, followed by lake morphology. As most of the cyanobacteiral genus detected in these plateau lakes were potential toxin-producers, this study indicated that in order to protect waters from toxic-bloom in the future, reducing nutrient loading and land-use practices are two practical approaches in plateau lake management. PMID:27819304

  12. Phytoplanktonic desmids community in Donghu Lake, Wuhan, China

    NASA Astrophysics Data System (ADS)

    Wei, Yinxin; Yu, Minjuan

    2005-03-01

    For compilation and comparison of desmids flora, the authors restudied the species composition, cell density and biomass of phytoplankton desmids collected at six stations in Donghu Lake at intervals of three months monitored from March of 1956 to February of 1957. A total of 122 taxa belonging to 16 genera were identified from qualitative and quantitative samples. Species of Cosmarium were the most popular ones occupying about 41% of the total species. Based on the observations, the annual mean values of the cell density and biomass were 132.11×102 cells/L and 0.09 mg/L. Cosmarium, Staurastrum, Staurodesmus and Closterium dominated and contributed more than 70% of the total cell density and biomass at six stations in four seasons. The maximum species number, cell density and biomass in autumn revealed that the highest variety (64 taxa, 1296×102 cells/L and 0.889 mg/L respectively) occurred at Station 3 located in the southern part of Donghu Lake. From then on to the mid 1990s the desmids community decreased sharply in Donghu Lake, resulted clearly from eutrophication in the lake.

  13. A DPSIR model for ecological security assessment through indicator screening: a case study at Dianchi Lake in China.

    PubMed

    Wang, Zhen; Zhou, Jingqing; Loaiciga, Hugo; Guo, Huaicheng; Hong, Song

    2015-01-01

    Given the important role of lake ecosystems in social and economic development, and the current severe environmental degradation in China, a systematic diagnosis of the ecological security of lakes is essential for sustainable development. A Driving-force, Pressure, Status, Impact, and Risk (DPSIR) model, combined with data screening for lake ecological security assessment was developed to overcome the disadvantages of data selection in existing assessment methods. Correlation and principal component analysis were used to select independent and representative data. The DPSIR model was then applied to evaluate the ecological security of Dianchi Lake in China during 1988-2007 using an ecological security index. The results revealed a V-shaped trend. The application of the DPSIR model with data screening provided useful information regarding the status of the lake's ecosystem, while ensuring information efficiency and eliminating multicollinearity. The modeling approach described here is practical and operationally efficient, and provides an attractive alternative approach to assess the ecological security of lakes.

  14. [An evaluation of net carbon sink effect and cost/benefits of a rice-rape rotation ecosystem under long-term fertilization from Tai Lake region of China].

    PubMed

    Li, Jie-Jing; Pan, Gen-Xing; Zhang, Xu-Hui; Fei, Qing-Hua; Li, Zhi-Peng; Zhou, Ping; Zheng, Ju-Feng; Qiu, Duo-Sheng

    2009-07-01

    Taking a long-term fertilized rice-rape rotation system in Taihu Lake as test objective, its annual C balance and economic benefit were estimated, based on the measurement of past years grain yield, litter C content, and field CO2 emission as well as the investigation of material and management inputs. The calculated annual C sink under different fertilizations ranged from 0.9 t C x hm(-2) x a(-1) to 7.5 t C x hm(-2) x a(-1), and the net C sink effect under combined inorganic/organic fertilization was three folds as that under chemical fertilization. The C cost of material input ranged from 0.37 t C x hm(-2) x a(-1) to 1.13 t C x hm(-2) x a(-1), and that of management input ranged from 1.69 t C x hm(-2) x a(-1) to 1.83 t C x hm(-2) x a(-1). The annual economic benefit ranged from 5.8 x 10(3) CNY x hm(-2) x a(-1) to 16.5 x 10(3) CNY x hm(-2) x a(-1), and was 2.1 times higher under combined fertilization than under chemical fertilization. Comparing with that under chemical fertilization, the marginal cost for per ton C sink under combined inorganic/organic fertilization was estimated as 217.1 CNY x t(-1) C, very close to the C price of 20 Euro x t(-1) C in the EU. In sum, under combined inorganic/organic fertilization, this rice paddy ecosystem could not only have higher productivity, but also present greater net C sink effect and higher economic benefit, compared with under chemical fertilizer fertilization.

  15. Volcano and earthquake hazards in the Crater Lake region, Oregon

    USGS Publications Warehouse

    Bacon, Charles R.; Mastin, Larry G.; Scott, Kevin M.; Nathenson, Manuel

    1997-01-01

    Crater Lake lies in a basin, or caldera, formed by collapse of the Cascade volcano known as Mount Mazama during a violent, climactic eruption about 7,700 years ago. This event dramatically changed the character of the volcano so that many potential types of future events have no precedent there. This potentially active volcanic center is contained within Crater Lake National Park, visited by 500,000 people per year, and is adjacent to the main transportation corridor east of the Cascade Range. Because a lake is now present within the most likely site of future volcanic activity, many of the hazards at Crater Lake are different from those at most other Cascade volcanoes. Also significant are many faults near Crater Lake that clearly have been active in the recent past. These faults, and historic seismicity, indicate that damaging earthquakes can occur there in the future. This report describes the various types of volcano and earthquake hazards in the Crater Lake area, estimates of the likelihood of future events, recommendations for mitigation, and a map of hazard zones. The main conclusions are summarized below.

  16. Decadal oscillation of lakes and aquifers in the upper Great Lakes region of North America: hydroclimatic implications

    USGS Publications Warehouse

    Watras, C.J.; Read, J.S.; Holman, K.D.; Liu, Z.; Song, Y.-Y.; Watras, A.J.; Morgan, S.; Stanley, E.H.

    2014-01-01

    We report a unique hydrologic time-series which indicates that water levels in lakes and aquifers across the upper Great Lakes region of North America have been dominated by a climatically-driven, near-decadal oscillation for at least 70 years. The historical oscillation (~13y) is remarkably consistent among small seepage lakes, groundwater tables and the two largest Laurentian Great Lakes despite substantial differences in hydrology. Hydrologic analyses indicate that the oscillation has been governed primarily by changes in the net atmospheric flux of water (P-E) and stage-dependent outflow. The oscillation is hypothetically connected to large-scale atmospheric circulation patterns originating in the mid-latitude North Pacific that support the flux of moisture into the region from the Gulf of Mexico. Recent data indicate an apparent change in the historical oscillation characterized by a ~12y downward trend beginning in 1998. Record low water levels region-wide may mark the onset of a new hydroclimatic regime.

  17. Environmental Indicators for the Coastal Region of North American Great Lakes: Introduction and Prospectus

    EPA Science Inventory

    Environmental indicators are benchmarks for the current conditions of the Great Lakes coastal region and provide measurable endpoints to assess the success of future management, conservation, protection, and restoration of this important resource.

  18. Measuring water storage fluctuations in lake Dongting, China, by Topex/Poseidon satellite altimetry.

    PubMed

    Zhang, Jiqun; Xu, Kaiqin; Yang, Yonghui; Qi, Lianhui; Hayashi, Seiji; Watanabe, Masataka

    2006-04-01

    Although satellite radar altimetry was developed and optimized for open oceans, it has been used to monitor variations in the level of inland water-bodies such as lakes and rivers. Here, for the first time, we have further used the altimetry-derived variation of water level for estimating the fluctuation of water storage as an addition to the present in situ water storage estimation systems to be used in remote areas and in emergency situation such as in the events flooding monitoring and for studying the effect of climate change. Lake Dongting, the second largest lake in China, influenced frequently by flooding, was, therefore, chosen to demonstrate the potential of the technique. By using the concept of an "assumed reference point", we converted Topex/Poseidon satellite altimetry data on water level variations in Lake Dongting to "water level" data. The "water level" time-series data and in situ water storage were used to establish a rating curve. From the rating curve, we converted data on "water level" derived from seven years (1993-1999) of Topex/Poseidon data to actual water storage in Lake Dongting. The result reveals that the seasonal and annual fluctuations of water storage occurred during the 1990s with a more frequent flooding at the late 1990s' especially the flooding in whole catchment level in 1998 and 1999. The study supports the usefulness of satellite altimetry for dense and continuous monitoring of the temporal variations in water dynamic in moderate to large lakes.

  19. Analysis of nutrient transport and ecological response in Honghu Lake, China by using a mathematical model.

    PubMed

    Zhang, Ting; Ban, Xuan; Wang, Xuelei; Cai, Xiaobin; Li, Enhua; Wang, Zhi; Yang, Chao; Zhang, Qing; Lu, Xiaorong

    2017-01-01

    A two-dimensional (2D) water quality model was established to determine the response of water quality variables and submerged aquatic vegetation biomass to load reduction from watershed inflows and enclosure aquaculture in Honghu Lake in China. Results showed that the total nitrogen (TN) and total phosphorus (TP) loads from upstream discharge were the major external loads in the lake, accounting for 70% and 63% of the total loads, respectively. Scenario simulation results indicated that 93.2% of the lake area in summer (August) and 89.5% in autumn (November) could reach the protective targets (TN<1.0mg/L) under 50% reduction of inflow TN loads. Meanwhile, 58.7% of the lake area in summer and 63.1% in autumn could reach the protective targets (TP<0.05mg/L) under 50% reduction of aquaculture areas. The mass budget results of TN and TP showed that TP immobilisation was larger than TN immobilisation. The immobilisations for TN and TP from July to September were higher than those of other months under the combined impacts of increasing runoff during the wet period, phytoplankton bloom and water residence time. The 2D water quality model provided a relevant example for assessing the effects of runoff and aquaculture activities and served as scientific support for lake management to improve water quality in large shallow macrophytic lakes.

  20. Effects of Land Use on Lake Nutrients: The Importance of Scale, Hydrologic Connectivity, and Region

    PubMed Central

    Soranno, Patricia A.; Cheruvelil, Kendra Spence; Wagner, Tyler; Webster, Katherine E.; Bremigan, Mary Tate

    2015-01-01

    Catchment land uses, particularly agriculture and urban uses, have long been recognized as major drivers of nutrient concentrations in surface waters. However, few simple models have been developed that relate the amount of catchment land use to downstream freshwater nutrients. Nor are existing models applicable to large numbers of freshwaters across broad spatial extents such as regions or continents. This research aims to increase model performance by exploring three factors that affect the relationship between land use and downstream nutrients in freshwater: the spatial extent for measuring land use, hydrologic connectivity, and the regional differences in both the amount of nutrients and effects of land use on them. We quantified the effects of these three factors that relate land use to lake total phosphorus (TP) and total nitrogen (TN) in 346 north temperate lakes in 7 regions in Michigan, USA. We used a linear mixed modeling framework to examine the importance of spatial extent, lake hydrologic class, and region on models with individual lake nutrients as the response variable, and individual land use types as the predictor variables. Our modeling approach was chosen to avoid problems of multi-collinearity among predictor variables and a lack of independence of lakes within regions, both of which are common problems in broad-scale analyses of freshwaters. We found that all three factors influence land use-lake nutrient relationships. The strongest evidence was for the effect of lake hydrologic connectivity, followed by region, and finally, the spatial extent of land use measurements. Incorporating these three factors into relatively simple models of land use effects on lake nutrients should help to improve predictions and understanding of land use-lake nutrient interactions at broad scales. PMID:26267813

  1. Effects of land use on lake nutrients: The importance of scale, hydrologic connectivity, and region

    USGS Publications Warehouse

    Soranno, Patricia A.; Cheruvelil, Kendra Spence; Wagner, Tyler; Webster, Katherine E.; Bremigan, Mary Tate

    2015-01-01

    Catchment land uses, particularly agriculture and urban uses, have long been recognized as major drivers of nutrient concentrations in surface waters. However, few simple models have been developed that relate the amount of catchment land use to downstream freshwater nutrients. Nor are existing models applicable to large numbers of freshwaters across broad spatial extents such as regions or continents. This research aims to increase model performance by exploring three factors that affect the relationship between land use and downstream nutrients in freshwater: the spatial extent for measuring land use, hydrologic connectivity, and the regional differences in both the amount of nutrients and effects of land use on them. We quantified the effects of these three factors that relate land use to lake total phosphorus (TP) and total nitrogen (TN) in 346 north temperate lakes in 7 regions in Michigan, USA. We used a linear mixed modeling framework to examine the importance of spatial extent, lake hydrologic class, and region on models with individual lake nutrients as the response variable, and individual land use types as the predictor variables. Our modeling approach was chosen to avoid problems of multi-collinearity among predictor variables and a lack of independence of lakes within regions, both of which are common problems in broad-scale analyses of freshwaters. We found that all three factors influence land use-lake nutrient relationships. The strongest evidence was for the effect of lake hydrologic connectivity, followed by region, and finally, the spatial extent of land use measurements. Incorporating these three factors into relatively simple models of land use effects on lake nutrients should help to improve predictions and understanding of land use-lake nutrient interactions at broad scales.

  2. A Fast Algorithm to Estimate the Deepest Points of Lakes for Regional Lake Registration.

    PubMed

    Shen, Zhanfeng; Yu, Xinju; Sheng, Yongwei; Li, Junli; Luo, Jiancheng

    2015-01-01

    When conducting image registration in the U.S. state of Alaska, it is very difficult to locate satisfactory ground control points because ice, snow, and lakes cover much of the ground. However, GCPs can be located by seeking stable points from the extracted lake data. This paper defines a process to estimate the deepest points of lakes as the most stable ground control points for registration. We estimate the deepest point of a lake by computing the center point of the largest inner circle (LIC) of the polygon representing the lake. An LIC-seeking method based on Voronoi diagrams is proposed, and an algorithm based on medial axis simplification (MAS) is introduced. The proposed design also incorporates parallel data computing. A key issue of selecting a policy for partitioning vector data is carefully studied, the selected policy that equalize the algorithm complexity is proved the most optimized policy for vector parallel processing. Using several experimental applications, we conclude that the presented approach accurately estimates the deepest points in Alaskan lakes; furthermore, we gain perfect efficiency using MAS and a policy of algorithm complexity equalization.

  3. Determination and occurrence of retinoids in a eutrophic lake (Taihu Lake, China): cyanobacteria blooms produce teratogenic retinal.

    PubMed

    Wu, Xiaoqin; Jiang, Jieqiong; Hu, Jianying

    2013-01-15

    Besides retinoic acids (RAs), some retinoids such as retinal (RAL) and retinol (ROH), which are considered as RA precursors in vertebrates, are also reported to be teratogenic agents. In this study we investigated four RA precursors including RAL, ROH, retinyl palmitate, and β-carotene in the eutrophic Taihu Lake, China, by developing a sensitive analytical method. RAL and β-carotene were widely detected in natural cyanobacteria blooms and lake water. Intracellular concentrations of RAL and β-carotene in blooms were 9.4 to 6.9 × 10(3) and 3.4 to 1.8 × 10(5) ng L(-1), respectively, and their concentrations in lake water were up to 1.4 × 10 ng L(-1) (RAL) and 9.8 × 10(2) ng L(-1) (β-carotene). The good correlation between intracellular concentrations of RAL and RAs implied that RAL was involved in the production of RAs by cyanobacteria blooms. Further examination of 39 cyanobacteria and algae species revealed that most species could produce RAL and β-carotene. The greatest amount of RAL was found in Chlamydomonas sp. (FACHB-715; 1.9 × 10(3) ng g(-1) dry weight). As the main cyanobacteria in Taihu Lake, many Microcystis species could produce high amounts of RAL and were thought to greatly contribute to the production of RAL measured in the blooms. Productions of RAL and β-carotene by cyanobacteria were associated with species, origin location, and growth stage. The results in this study present the existence of a potential risk to aquatic animals living in a eutrophic environment from a high concentration of RAL in cyanobacteria blooms and also provide a clue for further investigating the mechanism underlying the biosynthetic pathway of RAs in cyanobacteria and algae.

  4. Paleoenvironmental changes in the Western Great Lakes National Parks since deglaciation: Implications for the effect of the Great Lakes on regional climate

    SciTech Connect

    Winkler, M.G.

    1995-09-01

    Pollen and charcoal analyses of lake and bog core sediments from Voyageur`s National Park and the Apostle Islands National Lakeshore provide evidence of regional Holocene climate changes for the western Great Lakes that differ from paleoclimates interpreted for regions of the Midwest more distant from the Great Lakes. The timing of the middle Holocene dry period when prairie and oak-savannah expanded in the Midwest occurs between 9000 and 5000 yr B. P. in the northern regions, but between 5600 and 3500 yr B.P. in the lower tier of the northern midwestern states away from the lakes.

  5. Lake Urmia (Iran): can future socio-ecologically motivated river basin management restore lake water levels in an arid region with extensive agricultural development?

    NASA Astrophysics Data System (ADS)

    Fazel, Nasim; Berndtsson, Ronny; Bertacchi Uvo, Cintia; Klove, Bjorn; Madani, Kaveh

    2015-04-01

    Lake Urmia, one of the world's largest hyper saline lakes located in northwest of Iran, is a UNESCO Biosphere Reserve and Ramsar site, protected as a national park and, supports invaluable and unique biodiversity and related ecosystem services for the region's 6.5 million inhabitants. Due to increased development of the region's water resources for agriculture and industry and to a certain extent climate change, the lake has started to shrink dramatically since 1995 and now is holding less than 30 percent of its volume. Rapid development in agricultural sector and land-use changes has resulted in immense construction of dams and water diversions in almost all lake feeding rivers, intensifying lake shrinking, increasing salinity and degrading its ecosystem. Recently, lake's cultural and environmental importance and social pressure has raised concerns and brought government attention to the lake restoration plans. Along with poor management, low yield agriculture as the most water consuming activity in the region with, rapid, insufficient development is one of the most influential drivers in the lake desiccation. Part of the lake restoration plans in agricultural sector is to restrict the agricultural areas in the main feeding river basins flowing mostly in the southern part of the lake and decreasing the agricultural water use in this area. This study assess the efficiency and effectiveness of the proposed plans and its influence on the lake level rise and its impacts on economy in the region using a system dynamics model developed for the Lake consist of hydrological and agro-economical sub-systems. The effect of decrease in agricultural area in the region on GDP and region economy was evaluated and compared with released water contribution in lake level rise for a five year simulation period.

  6. Long term (1997-2014) spatial and temporal variations in nitrogen in Dongting Lake, China

    PubMed Central

    Tian, Zebin; Zheng, Binghui; Wang, Lijing; Li, Liqiang; Wang, Xing; Li, Hong; Norra, Stefan

    2017-01-01

    In order to protect the water quality of Dongting Lake, it is significant to find out its nitrogen pollution characteristics. Using long-term monthly to seasonally data (1997–2014), we investigated the spatial and temporal variations in nitrogen in Dongting Lake, the second largest freshwater lake in China. The average concentrations of total nitrogen (TN) in the eastern, southern, and western parts of the lake were 1.77, 1.56, and 1.35 mg/L, respectively, in 2014. TN pollution was generally worse in the southern area than in the western area. Concentrations showed temporal variation, and were significantly higher during the dry season than during the wet season. Based on the concentration and growth rate of TN, three different stages were identified in the long term lake data, from 1997 to 2002, from 2003 to 2008, and from 2009 to 2014, during which the concentrations and the growth rate ranged from 1.09–1.51 mg/L and 22.09%-40.03%, 1.05–1.57 mg/L and -9.05%-7.74%, and 1.68–2.02 mg/L and 57.99%-60.41%, respectively. The main controls on the lake water TN concentrations were the quality and quantity of the lake inflows, spatial and temporal variations in hydrodynamic conditions within the lake (flow velocity, flow direction), and point and nonpoint inputs from human activities. Diffuse nutrient losses from agricultural land are a significant contributor. As a priority, the local government should aim to control the pollutant inputs from upstream and non-point nutrient losses from land. PMID:28166245

  7. Long term (1997-2014) spatial and temporal variations in nitrogen in Dongting Lake, China.

    PubMed

    Tian, Zebin; Zheng, Binghui; Wang, Lijing; Li, Liqiang; Wang, Xing; Li, Hong; Norra, Stefan

    2017-01-01

    In order to protect the water quality of Dongting Lake, it is significant to find out its nitrogen pollution characteristics. Using long-term monthly to seasonally data (1997-2014), we investigated the spatial and temporal variations in nitrogen in Dongting Lake, the second largest freshwater lake in China. The average concentrations of total nitrogen (TN) in the eastern, southern, and western parts of the lake were 1.77, 1.56, and 1.35 mg/L, respectively, in 2014. TN pollution was generally worse in the southern area than in the western area. Concentrations showed temporal variation, and were significantly higher during the dry season than during the wet season. Based on the concentration and growth rate of TN, three different stages were identified in the long term lake data, from 1997 to 2002, from 2003 to 2008, and from 2009 to 2014, during which the concentrations and the growth rate ranged from 1.09-1.51 mg/L and 22.09%-40.03%, 1.05-1.57 mg/L and -9.05%-7.74%, and 1.68-2.02 mg/L and 57.99%-60.41%, respectively. The main controls on the lake water TN concentrations were the quality and quantity of the lake inflows, spatial and temporal variations in hydrodynamic conditions within the lake (flow velocity, flow direction), and point and nonpoint inputs from human activities. Diffuse nutrient losses from agricultural land are a significant contributor. As a priority, the local government should aim to control the pollutant inputs from upstream and non-point nutrient losses from land.

  8. Heavy Metal Pollution, Fractionation, and Potential Ecological Risks in Sediments from Lake Chaohu (Eastern China) and the Surrounding Rivers

    PubMed Central

    Zhang, Lei; Liao, Qianjiahua; Shao, Shiguang; Zhang, Nan; Shen, Qiushi; Liu, Cheng

    2015-01-01

    Heavy metal (Cr, Ni, Cu, Zn, Cd, and Pb) pollution, fractionation, and ecological risks in the sediments of Lake Chaohu (Eastern China), its eleven inflowing rivers and its only outflowing river were studied. An improved BCR (proposed by the European Community Bureau of Reference) sequential extraction procedure was applied to fractionate heavy metals within sediments, a geoaccumulation index was used to assess the extent of heavy metal pollution, and a risk assessment code was applied to evaluate potential ecological risks. Heavy metals in the Shuangqiao and Nanfei Rivers were generally higher than the other studied sites. Of the three Lake Chaohu sites, the highest concentrations were identified in western Chaohu. Heavy metal pollution and ecological risks in the lake’s only outflowing river were similar to those in the eastern region of the lake, to which the river is connected. Heavy metal concentrations occurred in the following order: Cd > Zn > Cu > Pb ≈ Ni ≈ Cr. Cr, Ni, and Cu made up the largest proportion of the residual fraction, while Cd was the most prominent metal in the exchangeable and carbonate-included fraction. Cd posed the greatest potential ecological risk; the heavy metals generally posed risks in the following order: Cd > Zn > Cu > Ni > Pb > Cr. PMID:26561822

  9. Regional Analysis of the Hazard Level of Glacial Lakes in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Chisolm, Rachel E.; Jhon Sanchez Leon, Walter; McKinney, Daene C.; Cochachin Rapre, Alejo

    2016-04-01

    The Cordillera Blanca mountain range is the highest in Peru and contains many of the world's tropical glaciers. This region is severely impacted by climate change causing accelerated glacier retreat. Secondary impacts of climate change on glacier retreat include stress on water resources and the risk of glacial lake outburst floods (GLOFs) from the many lakes that are forming and growing at the base of glaciers. A number of GLOFs originating from lakes in the Cordillera Blanca have occurred over the last century, several of which have had catastrophic impacts on cities and communities downstream. Glaciologists and engineers in Peru have been studying the lakes of the Cordillera Blanca for many years and have identified several lakes that are considered dangerous. However, a systematic analysis of all the lakes in the Cordillera Blanca has never before been attempted. Some methodologies for this type of systematic analysis have been proposed (eg. Emmer and Vilimek 2014; Wang, et al. 2011), but as yet they have only been applied to a few select lakes in the Cordillera Blanca. This study uses remotely sensed data to study all of the lakes of the Glacial Lake Inventory published by the Glaciology and Water Resources Unit of Peru's National Water Authority (UGRH 2011). The objective of this study is to assign a level of potential hazard to each glacial lake in the Cordillera Blanca and to ascertain if any of the lakes beyond those that have already been studied might pose a danger to nearby populations. A number of parameters of analysis, both quantitative and qualitative, have been selected to assess the hazard level of each glacial lake in the Cordillera Blanca using digital elevation models, satellite imagery, and glacier outlines. These parameters are then combined to come up with a preliminary assessment of the hazard level of each lake; the equation weighting each parameter draws on previously published methodologies but is tailored to the regional characteristics

  10. [Climatic suitability of single cropping rice planting region in China].

    PubMed

    Duan, Ju-Qi; Zhou, Guang-Sheng

    2012-02-01

    To clarify the leading climate factors affecting the distribution of single cropping rice planting region in China at national and annual temporal scales and to reveal the potential distribution and climatic suitability divisions of this planting region in China could not only provide scientific basis for optimizing the allocation of single cropping rice production, modifying planting pattern, and introducing fine varieties, but also ensure the food security of China. In this paper, the potential climate factors affecting the single cropping rice distribution in China at regional and annual scales were selected from related literatures, and the single cropping rice geographic information from the national agro-meteorological observation stations of China Meteorological Administration (CMA), together with the maximum entropy model (MaxEnt) and spatial analyst function of Arc-GIS software, were adopted to clarify the leading climate factors affecting the potential distribution of single cropping rice planting region in China, and to construct a model about the relationships between the potential distribution of the planting region and the climate. The results showed that annual precipitation, moisture index, and days of not less than 18 degrees C stably were the leading climate factors affecting the potential distribution of single cropping rice planting region in China, with their cumulative contribution rate reached 94.5% of all candidate climate factors. The model constructed in this paper could well simulate the potential distribution of single cropping rice planting region in China. According to the appearance frequency, the low, medium and high climatic suitability divisions of single cropping rice planting region in China were clarified, and the climate characteristics of the planting region in each climatic suitability division were analyzed.

  11. Water Quality and Evaluation of Pesticides in Lakes in the Ridge Citrus Region of Central Florida

    USGS Publications Warehouse

    Choquette, Anne F.; Kroening, Sharon E.

    2009-01-01

    Water chemistry, including major inorganic constituents, nutrients, and pesticide compounds, was compared between seven lakes surrounded by citrus agriculture and an undeveloped lake on the Lake Wales Ridge (herein referred to as the Ridge) in central Florida. The region has been recognized for its vulnerability to the leaching of agricultural chemicals into the subsurface due to factors including soils, climate, and land use. About 40 percent of Florida's citrus cultivation occurs in 'ridge citrus' areas characterized by sandy well drained soils, with the remainder in 'flatwoods citrus' characterized by high water tables and poorly drained soils. The lakes on the Ridge are typically flow-through lakes that exchange water with adjacent and underlying aquifer systems. This study is the first to evaluate the occurrence of pesticides in lakes on the Ridge, and also represents one of the first monitoring efforts nationally to focus on regional-scale assessment of current-use pesticides in small- to moderate-sized lakes (5 to 393 acres). The samples were collected between December 2003 and September 2005. The lakes in citrus areas contained elevated concentrations of major inorganic constituents (including alkalinity, total dissolved solids, calcium, magnesium, sodium, potassium, chloride, and sulfate), total nitrogen, pH, and pesticides compared to the undeveloped lake. Nitrate (as N) and total nitrogen concentrations were typically elevated in the citrus lakes, with maximum values of 4.70 and 5.19 mg/L (milligrams per liter), respectively. Elevated concentrations of potassium, nitrate, and other inorganic constituents in the citrus lakes likely reflect inputs from the surficial ground-water system that originated predominantly from agricultural fertilizers, soil amendments, and inorganic pesticides. A total of 20 pesticide compounds were detected in the lakes, of which 12 compounds exceeded the standardized reporting level of 0.06 ug/L (microgram per liter). Those

  12. Effects of Different Saline-Alkaline Conditions on the Characteristics of Phytoplankton Communities in the Lakes of Songnen Plain, China

    PubMed Central

    Zang, Shuying; Fan, Yawen; Ye, Huaxiang

    2016-01-01

    Many lakes located in the Songnen Plain of China exhibit a high saline-alkaline level. 25 lakes in the Songnen Plain were selected as research objects in this study. Water samples in these lakes were collected from June to August in 2008. Total Dissolved Solids (TDS) and Total Alkalinity (TA) were measured to assess the saline-alkaline level, and partial canonical correspondence analysis (CCA) was conducted as well. The results show that the majority of these lakes in the study area could be categorized into HCO3−-Na+-I type. According to the TDS assessment, of the total 25 lakes, there are 14 for freshwater, 7 for brackish water and 4 for saltwater; and the respective range of TA was from 0.98 to 40.52. The relationship between TA and TDS indicated significant linear relationship (R2 = 0.9292) in the HCO3−-Na+-I type lakes in the Songnen Plain. There was a general trend that cell density, genera richness and taxonomic diversity decreased with the increase of saline-alkaline gradient, whereas a contrary trend was observed for the proportion of dominant species. When the TDS values were above 3×103mg/L and the TA values were above 15mg/L, there was a significant reduction in cell density, genera richness and biodiversity, and their corresponding values were respectively below 10×106 (ind/L), 15 and approximately 2.5. Through the partial canonical correspondence analysis (CCA), 10.7% of the genera variation was explained by pure saline-alkaline variables. Cyclotella meneghiniana, Melosira ambigua and Melosira granulate were found to become the dominant species in most of these lakes, which indicated that there may be rather wide saline-alkaline niches for common dominant species. About one-quarters of the genera which have certain tolerance to salinity and alkalinity preferred to live in the regions with relatively higher saline-alkaline levels in this study. PMID:27749936

  13. Diversity analysis of Burkholderia cepacia complex in the water bodies of West Lake, Hangzhou, China.

    PubMed

    Fang, Yuan; Xie, Guan-Lin; Lou, Miao-Miao; Li, Bin; Muhammad, Ibrahim

    2011-04-01

    A survey of Burkholderia cepacia complex (Bcc) species was conducted in water bodies of West Lake in China. A total of 670 bacterial isolates were recovered on selective media. Out of them, 39.6% (265 isolates) were assigned to the following species: Burkholderia multivorans, Burkholderia cenocepacia recA lineage IIIA, IIIB, Burkholderia stabilis, Burkholderia vietnamiensis, and Burkholderia seminalis while B. cenocepacia is documented as a dominant Bcc species in water of West Lake. In addition, all Bcc isolates tested were PCR negative for the cblA and esmR transmissibility marker genes except B. cenocepacia IIIB A8 which was positive for esmR genelater. The present study raises great concerns on the role of West Lake as a "reservoir" for potential Bcc pathogenic strains.

  14. Alkenone temperature and salinity: An evaluation of long chain C37 alkenone in Lake Qinghai, China

    NASA Astrophysics Data System (ADS)

    Liu, W.; Liu, Z.; Fu, M.; An, Z.

    2007-12-01

    In recently years, the alkenone unsaturation index (Uk'37=C37:.2/(C37:2+ C37:3)) has been used to reconstructed paleo-temperature for lacustrine sediments. However, few studies have addressed whether the relative abundance of the C37:4 alkenone to the total C37 production (C37:4 percent) can reflect surface salinity changes in lake systems. Here we present the distribution of C37 long chain alkenone of modern lake sediments in Qinghai Lake, Qing-Tibet Plateau, to evaluate significance of abundance change of long chain C37 alkenone as an indicator of lake paleo-enviromental evolution. A group of surface sediments from different locations in the lake have been analyzed in this study. The results of long chain C37 alkenone from 28 surface sediments analyses shown relative abundance of C37:4 alkenone to total C37 production (C37:4 percent) change from 14.5 to 48.6 percent and the abundance of C37:4 alkenone is increasing with decreasing salinity of lake water. For the salinity lake in land, we suggested the relative abundance of C37:4 alkenone in lake sediments may be a indicator of paleo-silinity; We have also found that Uk'37 values are weakly correlated with salinity and C37:4 percent changes, implying that potential minor contributions of temperature and salinity effects to C37:4 percent and Uk'37 respectively cannot be excluded in this study. However, since these contributions are weak, we suggest that the C37:4 percent proxy can be used to reconstruct paleo-salinity changes at a regional scale, especially in lake systems, while Uk'37 remains as a powerful tool for reconstructions of paleo-temperature changes in the lake systems.

  15. Eutrophication assessment and management methodology of multiple pollution sources of a landscape lake in North China.

    PubMed

    Chen, Yanxi; Niu, Zhiguang; Zhang, Hongwei

    2013-06-01

    Landscape lakes in the city suffer high eutrophication risk because of their special characters and functions in the water circulation system. Using a landscape lake HMLA located in Tianjin City, North China, with a mixture of point source (PS) pollution and non-point source (NPS) pollution, we explored the methodology of Fluent and AQUATOX to simulate and predict the state of HMLA, and trophic index was used to assess the eutrophication state. Then, we use water compensation optimization and three scenarios to determine the optimal management methodology. Three scenarios include ecological restoration scenario, best management practices (BMPs) scenario, and a scenario combining both. Our results suggest that the maintenance of a healthy ecosystem with ecoremediation is necessary and the BMPs have a far-reaching effect on water reusing and NPS pollution control. This study has implications for eutrophication control and management under development for urbanization in China.

  16. Characterization of heavy metals in water and sediments in Taihu Lake, China.

    PubMed

    Tao, Yu; Yuan, Zhang; Wei, Meng; Xiaona, Hu

    2012-07-01

    To explore a comprehensive status of heavy metals in the Taihu Lake, which is one of the most important waters in China, water and sediment samples were taken throughout the lake during April to May of 2010, and metal elements (Cu, Cd, Cr, Ni, Pb, Sn, Sb, Zn, Mn) were analyzed in the water column, interstitial water and sediment. Relevant standards were used to assess the sediment and water quality. Results show that, in the lake water column, the average concentration of all metals ranged from 0.047 μg/l (Cd) to 8.778 μg/l (Zn). The concentration in the river water was usually higher than in the lake water for many metals. In the interstitial water Mn was significantly higher than that in water column, and other metals had no significant difference between the two media. In the surface sediment, average metal content ranged from 1.325 mg/kg (Cd) to 798.2 mg/kg (Mn). Spatially, contents of many metals were higher in Zhushan Bay than in other lake areas, and there existed a clear content gradient from the river to the lake for both water and sediment. On the sediment profiles, many metals presented an increasing trend from the depth of 15-20 cm to the top, which is indicative of the impact of increasingly intensive human activities from that period. Quality assessment indicates that metals in water phase are generally safe compared with USEPA "National Recommended Water Quality Criteria," with the exception of Mn in the interstitial water and Sb in the river water. Whereas the sediment is widely contaminated with metals to some extent compared with the "Consensus-Based Sediment Quality Guidelines," and Cu, Cr, and Ni are more likely to raise ecological risks. This work could be a basis for the ongoing China's criteria strategy.

  17. Crew escape system test at Naval Weapons Center, China Lake, California

    NASA Technical Reports Server (NTRS)

    1988-01-01

    As part of a crew escape system (CES) test program, a lifelike dummy is pulled by a tractor rocket from an airborne Convair-240 (C-240) aircraft at Naval Weapons Center, China Lake, California. A P-3 chase plane accompanies the C-240. The C-240 was modified with a space shuttle side hatch mockup for the tests which will evaluate candidate concepts developed to provide crew egress capability during Space Shuttle controlled gliding flight.

  18. Determination of polyfluoroalkyl phosphoric acid diesters, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, perfluoroalkyl carboxylic acids, and perfluoroalkane sulfonic acids in lake trout from the Great Lakes region.

    PubMed

    Guo, Rui; Reiner, Eric J; Bhavsar, Satyendra P; Helm, Paul A; Mabury, Scott A; Braekevelt, Eric; Tittlemier, Sheryl A

    2012-11-01

    A comprehensive method to extract perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphoric acid diesters simultaneously from fish samples has been developed. The recoveries of target compounds ranged from 78 % to 121 %. The new method was used to analyze lake trout (Salvelinus namaycush) from the Great Lakes region. The results showed that the total perfluoroalkane sulfonate concentrations ranged from 0.1 to 145 ng/g (wet weight) with perfluorooctane sulfonate (PFOS) as the dominant contaminant. Concentrations in fish between lakes were in the order of Lakes Ontario ≈ Erie > Huron > Superior ≈ Nipigon. The total perfluoroalkyl carboxylic acid concentrations ranged from 0.2 to 18.2 ng/g wet weight. The aggregate mean perfluorooctanoic acid (PFOA) concentration in fish across all lakes was 0.045 ± 0.023 ng/g. Mean concentrations of PFOA were not significantly different (p > 0.1) among the five lakes. Perfluoroalkyl phosphinic acids were detected in lake trout from Lake Ontario, Lake Erie, and Lake Huron with concentration ranging from non-detect (ND) to 0.032 ng/g. Polyfluoroalkyl phosphoric acid diesters were detected only in lake trout from Lake Huron, at levels similar to perfluorooctanoic acid.

  19. Glacier lake outburst floods of the Guangxieco Lake in 1988 in Tibet, China

    NASA Astrophysics Data System (ADS)

    Liu, J. J.; Cheng, Z. L.; Li, Y.

    2013-09-01

    Glacial lake outburst floods (GLOFs) have become more frequent and attracted more and more attention under conditions of global warming. However, there are few observations of the reasons for outbursts and their processes because of their unexpected occurrence and their inaccessible location in high-elevation areas. The GLOF of the Guangxieco Lake, which is the only outburst lake below an elevation of 4000 m in Tibet, provides a case study for discussing the reasons for outbursts. This paper reconstructs the process in detail using geomorphological evidence, interviews of the local inhabitants, archive material and satellite images. It was found that: (1) There were three main reasons for the GLOF in 1988: intense pre-precipitation and persistent high temperatures before the outburst, ice avalanche by rapid movement of the Gongzo Glacier and low self-stability of the end-moraine dam by perennial piping. (2) The GLOF with the peak discharge of 1270 m3 s-1 was evolved along the Midui Valley following sediment-laden flow-non-viscous debris flow-viscous debris flow-non-viscous debris flow-sediment-laden flood. Eventually the sediment-laden floods blocked the Palongzangbu River. (3) Comparing the conditions for the outburst in 1988 and at present, the possibility of a future outburst is thought to be small unless the glacier moves rapidly again.

  20. The 1988 glacial lake outburst flood in Guangxieco Lake, Tibet, China

    NASA Astrophysics Data System (ADS)

    Liu, J.-J.; Cheng, Z.-L.; Li, Y.

    2014-11-01

    The 1988 glacial lake outburst flood (GLOF) in Guangxieco Lake is studied based on geomorphological evidence, interviews with local residents, field surveys in 1990 and 2007, and satellite images from different years. The findings are as follows. (1) The outburst event was caused by two major factors, namely, intense pre-precipitation and persistent high temperatures before the outburst and the low self-stability of the terminal moraine dam as a result of perennial piping. (2) The GLOF, with the peak discharge rate of 1270 m3 s-1, evolved along Midui Valley in the following order: sediment-laden flow, viscous debris flow, non-viscous debris flow, and sediment-laden flood, which was eventually blocked by Palongzangbu River. (3) A comparison between the conditions during the outburst in 1988 and the present conditions suggests a small possibility of a future outburst unless drastic changes occur in landscape and climate. Reconstructing the outburst conditions and the GLOF processes is helpful in assessing a potential outburst in glacier lakes in Tibet.

  1. Bioavailability and preservation of organic phosphorus in freshwater sediments and its role in lake eutrophication

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lake eutrophication in China is a serious environmental concern, especially in lakes from the middle and lower reaches of Yangtze River region and Southwestern China Plateau. The dissolution of organic matter can result in release of phosphorus (P) from lake sediments and organic phosphate (Po) itse...

  2. Occurrence and spatial distributions of microcystins in Poyang Lake, the largest freshwater lake in China.

    PubMed

    Zhang, Dawen; Liao, Qiegen; Zhang, Li; Wang, Donggen; Luo, Linguang; Chen, Yuwei; Zhong, Jiayou; Liu, Jutao

    2015-01-01

    Occurrence and spatial distributions of microcystins (MCs; MC-RR, -YR, -LR, -LA, -LF, -LW) in Poyang Lake were studied during the period from July 6 to July 18, 2012, by using ultra-high-performance liquid chromatography-electrospray ionization tandem triple quadrupole/mass spectrometry (UPLC-MS/MS). MC-RR was the most dominant variant (94.70 and 84.73 % for intracellular (cellular MCs) and extracellular (dissolved MCs) MCs, respectively) in Poyang Lake, followed by MC-LR (4.65 and 13.17 %, respectively), MC-YR (0.8 and 2.63 %, respectively), and MC-LA (0.02 and 0.00 %), while MC-LW and MC-LF were not detected. Total MCs concentrations (intracellular +extracellular MCs) ranged between 0.0036 and 7.97 μg/L, with an average of 0.79 μg/L, and only two sampling stations with the total MCs concentrations exceeded the drinking water guideline level of 1 μg/L for MC-LR proposed by World Health Organization. The overall spatial pattern of intracellular and extracellular MCs in Poyang Lake demonstrates decreasing trends from east to west, and the south part higher than the north part. Intracellular MCs content was negatively correlated with total nitrogen (r = -0.34, p < 0.01) and NO3 (r = -0.35, p < 0.01), while no significant correlation was found between intracellular MCs concentration and total phosphorus, NH4, and NO2 (p > 0.05), suggesting that NO3 might be a regulating factor for MCs production in Poyang Lake. In addition, intracellular MCs concentrations were positively correlated with wind speed, Microcystis and Cyanobacteria biomass (r = 0.34-0.51, p < 0.05), indicating that wind speed plays an important role in the spatial distributions of MCs, and NO3, toxic cyanobacteria (mainly Microcystis), and wind speed seem to be the important forcing factors driving MCs spatial distributions in Poyang Lake.

  3. A REGIONAL ECOLOGICAL ANALYSIS OF THE GREAT LAKES BASIN

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) and Natural Resources Canada: Canada Centre for Remote Sensing (CCRS) are conducting a cooperative research landscape ecological study of the Great Lakes Basin. The analyses will include the areas located along the border of the Unit...

  4. Clustering oxbow lakes in the Upper-Tisza Region on the basis of stable isotope measurements

    NASA Astrophysics Data System (ADS)

    Babka, Beáta; Futó, István; Szabó, Szilárd

    2011-11-01

    SummarySeveral times a year the River Tisza floods areas between dikes, fills the oxbow lakes on the floodplain and changes their water. However the water addition in the oxbow lakes does not only take place through flooding; it is also likely that water can seep under the surface through the gravelled layers of the old river-beds, and furthermore, precipitation also plays a role. Our goal with this study is to acquire a full, comprehensive picture of the water addition of the oxbow lakes in the Upper-Tisza Region. Surface and groundwater samples were taken from the River Tisza, the oxbow lakes and the boreholes around four oxbow lakes, and stabile isotope ratios were measured. We can get information on the origin, the evaporation and the state of the waters, and the depth of the water table with the help of δ18O VSMOW (‰) and δD VSMOW (‰). During the examination the question we addressed was how oxbow lakes can be classified according to their water addition on the basis of their stable isotope ratios. The results from the Tisza and the oxbow lakes, as well as the results from the oxbow lakes on the reclaimed side and the floodplain are also isolated.

  5. A 60-year sedimentary record of natural and anthropogenic impacts on Lake Chenghai, China.

    PubMed

    Zan, Fengyu; Huo, Shouliang; Xi, Beidou; Zhang, Jingtian; Liao, Haiqing; Wang, Yue; Yeager, Kevin M

    2012-01-01

    Recent sediments from Lake Chenghai, China, were investigated at high temporal resolution to trace both natural and anthropogenic effects on the lake using total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), organic phosphorus (Po), inorganic phosphorus (Pi) and organic carbon and nitrogen stable isotopes (delta13Corg and delta15N) in a 137Cs-dated sediment core. The results indicated that the sedimentary record covers the last 60 years, during which the lake had undergone apparent changes in nutrient sources and productivity in response to nutrient loading. Prior to the late 1980s, the nutrient contents in sediments mainly originated from algae and lake productivity was relatively stable. Since the late 1980s, increasing TOC, TN and TP concentrations together with the change of delta13Corg and delta15N suggested anthropogenic perturbations in nutrient loading and lake productivity. Endogenic nutrients derived from algae and anthropogenic inputs were two important sources of sedimentary nutrients. The anthropogenic nutrients mainly originated from the discharge of industrial wastewater and artificial cultivation of Spirulina after the middle 1980s, and domestic wastewater discharged from Yongsheng County since 1993.

  6. Long Term Atmospheric and Erosional Pollution As Recorded in Lake Sediments from Yunnan, China

    NASA Astrophysics Data System (ADS)

    Hillman, A. L.; Abbott, M. B.; Yu, J.; Bain, D.; Chiou-Peng, T.

    2014-12-01

    Human activities including agriculture, metallurgy (e.g. mining, processing, smelting), and deforestation have altered cycles of erosion and sedimentation in lake environments for thousands of years. In the Yunnan province of southwestern China, where written records are incomplete, it is unclear when, where, and how much disturbance occurred. Lake sediments offer a means to investigate a wide variety of human activities. Here, we present a lake sediment record from Erhai (25°43'N, 100°12'E) based on trace metal concentrations that reveals substantial atmospheric and erosional pollution to the lake environment over the last 4,000 years. Sediments indicate the initiation of copper-based metallurgy at 3,600 years BP, the existence of which has been debated amongst archaeologists. Beginning 2,000 years BP, sedimentation rates increase and concentrations of metals such as aluminum, titanium, lead, and zinc increase. This is likely linked to increased sediment flux to the lake associated with the initiation of terraced agriculture according to historical documents. The most prominent feature of the record is an abrupt and intense increase in lead, silver, cadmium, and zinc beginning at 700 years BP. The peak of this increase occurs at 600 years BP and is consistent with historical records that the Mongols established the first government operated silver mine in Yunnan. Notably, the concentrations of lead during this time are an order of magnitude greater than modern day levels of pollution.

  7. Trimethylamine stimulated and dissolved organic matter inhibited methane production in sediment from the Poyang Lake, China.

    PubMed

    Wang, Jiajia; Liu, Chunying; Gong, Xiaofeng; Liu, Yuanmu; Chen, Chunli

    2016-10-01

    Methane (CH4) emitted from wetlands contributes significantly to the greenhouse effect. The Poyang Lake, the largest freshwater lake in China, is fed by five rivers and connects to the Yangtze River. The area of the lake fluctuates dramatically between drawdown and flood periods with large areas of wetlands. In order to understand the CH4 production capacity and factors that influence CH4 production in the wetland, a static closed chamber combined with a gas chromatograph technique was used to investigate the influence of substrates and electron acceptors on methanogenesis. The results showed that CH4 production capacity of sediments from the Poyang Lake was [Formula: see text] and it was stimulated by trimethylamine (TMA) to a great extent. Incubation temperature played a vital role on CH4 production in sediments and the optimum temperature for methanogenesis was 35°C. Minimum CH4 production capacity occurred with the addition of FeCl3, and the inhibitory effects of electron acceptors decreased in the sequence: FeCl3 > MnO2 > DOM > Fe2O3. In this study, DOM was demonstrated as one of the inhibitors to methanogenesis and TMA was the main substrate of methanogens in the sediments of the Poyang Lake whose pH value is 7.83.

  8. [Spatial Distribution of Stable Isotope from the Lakes in Typical Temperate Glacier Region].

    PubMed

    Shi, Xiao-yi; Pu, Tao; He, Yuan-qing; Lu, Hao; Niu, He-wen; Xia, Dun-sheng

    2016-05-15

    We focused mainly on the spatial variation and influencing factors of hydrogen and oxygen stable isotopes between water samples collected at the surface and different depths in the Lashi Lake in August, 2014. Hydrological supply characteristics of the lake in typical temperate glacier region were discussed. The results showed that the values of δ¹⁸O and δD in the Lashi Lake ranged from -12.98 per thousand to -8.16 per thousand with the mean of -9.75 per thousand and from -99.42 per thousand to -73.78 per thousand with the mean of -82.23 per thousand, respectively. There was a reversed spatial variation between δ¹⁸O and d. Relatively low values of δ¹⁸O with high values of d were found at the edge of the lake where the rivers drained into. Meanwhile, the values of d in the vertical profile varied little with depth, suggesting that the waters mixed sufficiently in the vertical direction. The d values increased at first and then decreased from east to west at different layers, but both increase and decrease exhibited different velocities, which were related to the river distribution, the locality of the lake and environmental conditions etc. River water and atmospheric precipitation were the main recharge sources of the Lashi Lake, and the melt-water of snow and ice might also be the supply resource. The δ¹⁸O values of lake water in glacier region decreased along the elevation (except for Lashi Lake), generally, this phenomenon was called "altitude effect". Moreover, high isotopic values of the lake water from non-glacier region were due to the evaporation effect.

  9. Climatic forcing of carbon-oxygen isotopic covariance in temperate-region marl lakes

    NASA Technical Reports Server (NTRS)

    Drummond, C. N.; Patterson, W. P.; Walker, J. C.

    1995-01-01

    Carbon and oxygen stable isotopic compositions of lacustrine carbonate from a southeastern Michigan marl lake display linear covariance over a range of 4.0% Peedee belemnite (PDB) in oxygen and 3.9% (PDB) in carbon. Mechanisms of delta 13 C-delta 18 O coupling conventionally attributed to lake closure in arid-region basins are inapplicable to hydrologically open lake systems. Thus, an alternative explanation of isotopic covariance in temperate region dimictic marl lakes is required. We propose that isotopic covariance is a direct record of change in regional climate. In short-residence-time temperate-region lake basins, summer meteoric precipitation is enriched in 18O relative to winter values, and summer organic productivity enriches epilimnic dissolved inorganic carbon in 13C. Thus, climate change toward longer summers and/or shorter winters could result in greater proportions of warm-month meteoric precipitation, longer durations of warm-month productivity, and net long-term enrichment in carbonate 18O and 13C. Isotopic covariance observed in the Michigan marl lake cores is interpreted to reflect postglacial warming from 10 to 3 ka followed by cooler mean annual temperature, a shift toward greater proportions of seasonal summer precipitation, a shortening of the winter season, or some combination of these three factors.

  10. Phytoplankton and eutrophication degree assessment of Baiyangdian Lake wetland, China.

    PubMed

    Wang, Xing; Wang, Yu; Liu, Lusan; Shu, Jianmin; Zhu, Yanzhong; Zhou, Juan

    2013-01-01

    Eight typical sampling sites were chosen to investigate the phytoplankton community structure and to assess the eutrophication degree of Baiyangdian Lake in 2009. Our results showed that among the total 133 species identified, Cyanophyta, Chlorophyta, and Bacillariophyta dominated the phytoplankton community. In spring, Chlorophyta and Bacillariophyta were the dominant phyla, and the dominant species included Chlorella sp., Chroomonas acuta Uterm., and Microcystis incerta Lemm.; the density of the phytoplankton ranged from 496 × 10(4) to 6256 × 10(4) cells/L with an average of 2384 × 10(4) cells/L. However, Chlorophyta and Cyanophyta became the dominant phyla in summer, and the dominant species were Chlorella sp., Leptolyngbya valderiana Anagn., and Nephrocytium agardhianum Nageli.; the density of the phytoplankton varied from 318 × 10(4) to 4630 × 10(4) cells/L with an average of 1785 × 10(4) cells/L. The density of the phytoplankton has increased significantly compared to the previous investigations in 2005. The index of Carlson nutritional status (TSIM) and the dominant genus assessment indicated that the majority of Baiyangdian Lake was in eutrophic state.

  11. Phytoplankton and Eutrophication Degree Assessment of Baiyangdian Lake Wetland, China

    PubMed Central

    Wang, Xing; Wang, Yu; Liu, Lusan; Shu, Jianmin; Zhu, Yanzhong; Zhou, Juan

    2013-01-01

    Eight typical sampling sites were chosen to investigate the phytoplankton community structure and to assess the eutrophication degree of Baiyangdian Lake in 2009. Our results showed that among the total 133 species identified, Cyanophyta, Chlorophyta, and Bacillariophyta dominated the phytoplankton community. In spring, Chlorophyta and Bacillariophyta were the dominant phyla, and the dominant species included Chlorella sp., Chroomonas acuta Uterm., and Microcystis incerta Lemm.; the density of the phytoplankton ranged from 496 × 104 to 6256 × 104 cells/L with an average of 2384 × 104 cells/L. However, Chlorophyta and Cyanophyta became the dominant phyla in summer, and the dominant species were Chlorella sp., Leptolyngbya valderiana Anagn., and Nephrocytium agardhianum Nageli.; the density of the phytoplankton varied from 318 × 104 to 4630 × 104 cells/L with an average of 1785 × 104 cells/L. The density of the phytoplankton has increased significantly compared to the previous investigations in 2005. The index of Carlson nutritional status (TSIM) and the dominant genus assessment indicated that the majority of Baiyangdian Lake was in eutrophic state. PMID:23983633

  12. Coupled atmospheric-hydrological modeling for feedback investigations in the Poyang lake catchment, China

    NASA Astrophysics Data System (ADS)

    Wagner, S.; Fersch, B.; Kunstmann, H.; Yang, C.; Yuan, F.; Yu, Z.

    2012-12-01

    Coupling terrestrial hydrological and atmospheric models allows investigations of the role of water in the earth system in a more integrative way. In particular, for the analysis of possible changes of the hydrological cycle due to human-induced climate change, land cover conversions, and water resources management feedback mechanisms among the earth surface, subsurface and atmosphere are crucial. Investigations of such feedback, which is primarily caused by water and energy fluxes, require a cross-compartment two-way coupled atmospheric-hydrological modeling system. For this purpose, we coupled the regional atmospheric model WRF-ARW and the distributed hydrological model HMS. Both models share the same land surface model: the Noah-LSM. This model system enables long term simulations for investigations of land use and/or climate changes on the hydrological cycle. The model system is applied for the Poyang lake basin in China with a catchment size of approximately 160,000 km2 using a spatial resolution of 10x10 km2. In addition to the projected climate change signals, human-induced rapid changes of land use occurred in the past and will likely continue for this region. Prior to the application of the coupled model system, offline simulations of the advanced weather research and forecast model (WRF-ARW) are performed to identify a suited setup for the study area. For this purpose, several configurations of WRF-ARW, using ECMWF's ERA-INTERIM reanalysis data as driving data, are compared and validated with publicly available observational data sets for the period 2003-2005. For the coupled system, the integration of HMS into WRF-ARW required in addition the implementation of an interface between saturated zone (groundwater model) and the LSM which enables the feedback between the different compartments. With this coupled model system, the potential of the integrated WRF-HMS simulations is evaluated by analyzing and comparing first simulation results with and without

  13. Ecological risk assessment of land use change in the Poyang Lake Eco-economic Zone, China.

    PubMed

    Xie, Hualin; Wang, Peng; Huang, Hongsheng

    2013-01-14

    Land use/land cover change has been attracting increasing attention in the field of global environmental change research because of its role in the social and ecological environment. To explore the ecological risk characteristics of land use change in the Poyang Lake Eco-economic Zone of China, an eco-risk index was established in this study by the combination of a landscape disturbance index with a landscape fragmentation index. Spatial distribution and gradient difference of land use eco-risk are analyzed by using the methods of spatial autocorrelation and semivariance. Results show that ecological risk in the study area has a positive correlation, and there is a decreasing trend with the increase of grain size both in 1995 and 2005. Because the area of high eco-risk value increased from 1995 to 2005, eco-environment quality declined slightly in the study area. There are distinct spatial changes in the concentrated areas with high land use eco-risk values from 1995 to 2005. The step length of spatial separation of land use eco-risk is comparatively long - 58 km in 1995 and 11 km in 2005 - respectively. There are still nonstructural factors affecting the quality of the regional ecological environment at some small-scales. Our research results can provide some useful information for land eco-management, eco-environmental harnessing and restoration. In the future, some measures should be put forward in the regions with high eco-risk value, which include strengthening land use management, avoiding unreasonable types of land use and reducing the degree of fragmentation and separation.

  14. Ecological Risk Assessment of Land Use Change in the Poyang Lake Eco-economic Zone, China

    PubMed Central

    Xie, Hualin; Wang, Peng; Huang, Hongsheng

    2013-01-01

    Land use/land cover change has been attracting increasing attention in the field of global environmental change research because of its role in the social and ecological environment. To explore the ecological risk characteristics of land use change in the Poyang Lake Eco-economic Zone of China, an eco-risk index was established in this study by the combination of a landscape disturbance index with a landscape fragmentation index. Spatial distribution and gradient difference of land use eco-risk are analyzed by using the methods of spatial autocorrelation and semivariance. Results show that ecological risk in the study area has a positive correlation, and there is a decreasing trend with the increase of grain size both in 1995 and 2005. Because the area of high eco-risk value increased from 1995 to 2005, eco-environment quality declined slightly in the study area. There are distinct spatial changes in the concentrated areas with high land use eco-risk values from 1995 to 2005. The step length of spatial separation of land use eco-risk is comparatively long—58 km in 1995 and 11 km in 2005—respectively. There are still nonstructural factors affecting the quality of the regional ecological environment at some small-scales. Our research results can provide some useful information for land eco-management, eco-environmental harnessing and restoration. In the future, some measures should be put forward in the regions with high eco-risk value, which include strengthening land use management, avoiding unreasonable types of land use and reducing the degree of fragmentation and separation. PMID:23343986

  15. Potential transport pathways of dust emanating from the playa of Ebinur Lake, Xinjiang, in arid northwest China

    NASA Astrophysics Data System (ADS)

    Ge, Yongxiao; Abuduwaili, Jilili; Ma, Long; Wu, Na; Liu, Dongwei

    2016-09-01

    In this paper, the HYSPLIT model, driven with reanalysis meteorological data from 1978 to 2013, was used to understand the potential transport characteristics of dust and salt dust emanating from the playa of Ebinur Lake in arid northwest China. Daily air parcel trajectories were computed forward for 8 days from an origin centered over Ebinur Lake at 100 m above ground level. Air parcel trajectory density plots were mapped for seven levels: 0-100 m agl., 100-500 m agl., 500-1000 m agl., 1000-1500 m agl., 1500-2000 m agl., 2000-3000 m agl., and 3000-5000 m agl. These show that potential dust transport pathways have clear seasonal differentiation. The potential transport distance of dust and salt dust is greatest in spring and summer. In autumn and winter, the potential transport of the high-density air trajectory is below 1000 m traveling a shorter distance. Potential dust transport pathways showed notifying directivity in different seasons and heights. Southeast in spring and summer, and north to northeast in autumn and winter are the two main potential transport channels of dust and salt dust. Accordingly, dust and salt dust from the playa of Ebinur Lake may influence the atmospheric processes and biogeochemical cycles of a vast region. The main area of influence of dust and salt dust is close to the source area, and will significantly accelerate the melting of snow and ice in the Tianshan Mountains. This highlights the urgent need to combine remote sensing, isotope and other methods to further research the transport characteristics of dust and salt dust from the playa of the Ebinur Lake.

  16. Spatial distribution, potential risk assessment, and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments of Lake Chaohu, China.

    PubMed

    Li, Chaocan; Huo, Shouliang; Yu, Zhiqiang; Xi, Beidou; Zeng, Xiangying; Wu, Fengchang

    2014-10-01

    Twenty-nine sediment samples were collected from Lake Chaohu, a shallow eutrophic lake in Eastern China, and were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) to determine the spatial distribution and exposure risks of PAHs. Three receptor models, the principal component analysis-multiple linear regression (PCA-MLR) model, the positive matrix factorization (PMF) model, and the Unmix model, were used in combination with the PAHs diagnostic ratios to investigate the potential source apportionment of PAHs. A clear gradient in the spatial distribution and the potential toxicity of PAHs was observed from west to east in the sediments of Lake Chaohu. ∑15PAH concentrations and the TEQ were in the range of 80.82-30 365.01 ng g(-1) d.w. and 40.77-614.03, respectively. The highest values of the aforementioned variables were attributed to urban-industrial pollution sources in the west lake region, and the levels decreased away from the river inlets. The three different models yielded excellent correlation coefficients between the predicted and measured levels of the 15 PAH compounds. Similarly, source apportionment results were derived from the three receptor models and the PAH diagnostic ratios, suggesting that the highest contribution to the PAHs was from coal combustion and wood combustion, followed by vehicular emissions. The PMF model yielded the following contributions to the PAHs from gasoline combustion, diesel combustion, unburned petroleum emissions, and wood combustion: 34.49, 24.61, 16.11, 13.01, and 11.78 %, respectively. The PMF model produced more detailed source apportionment results for the PAHs than the PCA-MLR and Unmix models.

  17. Landslides and Earthquake Lakes from the Wenchuan, China Earthquake - Can it Happen in the U.S.?

    NASA Astrophysics Data System (ADS)

    Stenner, H.; Cydzik, K.; Hamilton, D.; Cattarossi, A.; Mathieson, E.

    2008-12-01

    The May 12, 2008 M7.9 Wenchuan, China earthquake destroyed five million homes and schools, causing over 87,650 deaths. Landslides, a secondary effect of the shaking, caused much of the devastation. Debris flows buried homes, rock falls crushed cars, and landslides dammed rivers. Blocked roads greatly impeded emergency access, delaying response. Our August 2008 field experience in the affected area reminded us that the western United States faces serious risks posed by earthquake-induced landslides. The topography of the western U.S. is less extreme than that near Wenchuan, but earthquakes may still cause devastating landslides, damming rivers and blocking access to affected areas. After the Wenchuan earthquake, lakes rapidly rose behind landslide dams, threatening millions of lives. One landslide above Beichuan City created Tangjiashan Lake, a massive body of water upstream of Mianyang, an area with 5.2 million people, 30,000 of whom were killed in the quake. Potential failure of the landslide dam put thousands more people at risk from catastrophic flooding. In 1959, the M7.4 Hebgen Lake earthquake in Montana caused a large landslide, which killed 19 people and dammed the Madison River. The Army Corps excavated sluices to keep the dam from failing catastrophically. The Hebgen Lake earthquake ultimately caused 28 deaths, mostly from landslides, but the affected region was sparsely populated. Slopes prone to strong earthquake shaking and landslides in California, Washington, and Oregon have much larger populations at risk. Landslide hazards continue after the earthquake due to the effect strong shaking has on hillslopes, particularly when subjected to subsequent rain. These hazards must be taken into account. Once a landslide blocks a river, rapid and thoughtful action is needed. The Chinese government quickly and safely mitigated landslide dams that posed the greatest risk to people downstream. It took expert geotechnical advice, the speed and resources of the army

  18. Methane emissions from rice paddies natural wetlands, and lakes in China: synthesis and new estimate.

    PubMed

    Chen, Huai; Zhu, Qiu'an; Peng, Changhui; Wu, Ning; Wang, Yanfen; Fang, Xiuqin; Jiang, Hong; Xiang, Wenhua; Chang, Jie; Deng, Xiangwen; Yu, Guirui

    2013-01-01

    Sources of methane (CH4 ) become highly variable for countries undergoing a heightened period of development due to both human activity and climate change. An urgent need therefore exists to budget key sources of CH4 , such as wetlands (rice paddies and natural wetlands) and lakes (including reservoirs and ponds), which are sensitive to these changes. For this study, references in relation to CH4 emissions from rice paddies, natural wetlands, and lakes in China were first reviewed and then reestimated based on the review itself. Total emissions from the three CH4 sources were 11.25 Tg CH4  yr(-1) (ranging from 7.98 to 15.16 Tg CH4  yr(-1) ). Among the emissions, 8.11 Tg CH4  yr(-1) (ranging from 5.20 to 11.36 Tg CH4  yr(-1) ) derived from rice paddies, 2.69 Tg CH4  yr(-1) (ranging from 2.46 to 3.20 Tg CH4  yr(-1) ) from natural wetlands, and 0.46 Tg CH4  yr(-1) (ranging from 0.33 to 0.59 Tg CH4  yr(-1) ) from lakes (including reservoirs and ponds). Plentiful water and warm conditions, as well as its large rice paddy area make rice paddies in southeastern China the greatest overall source of CH4 , accounting for approximately 55% of total paddy emissions. Natural wetland estimates were slightly higher than the other estimates owing to the higher CH4 emissions recorded within Qinghai-Tibetan Plateau peatlands. Total CH4 emissions from lakes were estimated for the first time by this study, with three quarters from the littoral zone and one quarter from lake surfaces. Rice paddies, natural wetlands, and lakes are not constant sources of CH4 , but decreasing ones influenced by anthropogenic activity and climate change. A new progress-based model used in conjunction with more observations through model-data fusion approach could help obtain better estimates and insights with regard to CH4 emissions deriving from wetlands and lakes in China.

  19. Heavy metals in surface sediments of the shallow lakes in eastern China: their relations with environmental factors and anthropogenic activities.

    PubMed

    Zhang, Wenqiang; Jin, Xin; Di, Zhenzhen; Zhu, Xiaolei; Shan, Baoqing

    2016-12-01

    The aquatic environment is affected by heavy metal pollution. This study was conducted to test the hypothesis that environmental factors and anthropogenic activities influence the distributions and the risks posed by heavy metals in surface sediments in shallow lakes in eastern China, which is an area affected by rapid urbanization, industrialization, and population growth. Total Cd, Cr, Cu, Ni, Pb, Se, and Zn concentrations in sediment samples were determined using inductively coupled plasma optical emission spectrometry. The I geo showed that sediments in the lakes were moderately polluted with Cr, Cu, Pb, and Zn, and the EF method showed that Cd and Se were significantly enriched in lakes. The heavy metals were found to pose moderate risks in most of the lakes, except for Gaoyou Lake, Honghu Lake, Poyang Lake, and Weishan Lake. The RI method indicated that very high risks were posed in Dongting Lake and Poyang Lake. Cd was found to pose much higher levels of risk than the other metals. Significant correlations were found between the heavy metal concentrations and the total carbon, nitrogen, phosphorus, and sulfur concentrations. The gross domestic product represented anthropogenic activities well. The gross domestic product of an area and the gross domestic products of primary and secondary industries in an area all had significant relationships with the concentrations of Cu and Pb, indicating that anthropogenic activities have different impacts on pollution with different heavy metals. The gross domestic product index was found to be a driving force behind the pollution of lakes with heavy metals.

  20. Simulation of Lake Surface Heat Fluxes by the Canadian Small Lake Model: Offline Performance Assessment for Future Coupling with a Regional Climate Model

    NASA Astrophysics Data System (ADS)

    Pernica, P.; Guerrero, J. L.; MacKay, M.; Wheater, H. S.

    2014-12-01

    Lakes strongly influence local and regional climate especially in regions where they are abundant. Development of a lake model for the purpose of integration within a regional climate model is therefore a subject of scientific interest. Of particular importance are the heat flux predictions provided by the lake model since they function as key forcings in a fully coupled atmosphere-land-lake system. The first step towards a coupled model is to validate and characterize the accuracy of the lake model over a range of conditions and to identify limitations. In this work, validation results from offline tests of the Canadian Small Lake Model; a deterministic, computationally efficient, 1D integral model, are presented. Heat fluxes (sensible and latent) and surface water temperatures simulated by the model are compared with in situ observations from two lakes; Landing Lake (NWT, Canada) and L239 (ELA, Canada) for the 2007-2009 period. Sensitivity analysis is performed to identify key parameters important for heat flux predictions. The results demonstrate the ability of the 1-D lake model to reproduce both diurnal and seasonal variations in heat fluxes and surface temperatures for the open water period. These results, in context of regional climate modelling are also discussed.

  1. Geophysical Evidence for Holocene Lake-Level Change in Southern California (Dry Lake): Additional Evidence for a Regional Early Holocene High Stand

    NASA Astrophysics Data System (ADS)

    Kirby, M. E.; Bird, B. W.; Howat, I. M.; Tulaczyk, S.

    2007-12-01

    Ground penetrating radar data are used to develop a Holocene history of basin sedimentation in a small, alpine lake in Southern California (Dry Lake). We define three depositional sequences spanning the past 9,000 calendar years before present (cy BP). Although, the basin contains sediments clearly older than the Holocene, we focus on the past 9,000 cy BP to match our similarly aged sediment cores. Sequence I represents the first phase of an early Holocene high stand. A major regression, perhaps following the 8,200 year cold event, separates Sequence I from Sequence II. The timing of this regression is approximately coeval with major regressions at Owens Lake (Bacon et al., 2006) in southeastern California and Tulare Lake (Negrini et al., 2006) in the southern Central Valley of California. Sequence II represents the second phase of the early Holocene high stand. This second high stand phase is also observed at Tulare Lake but not at Owens Lake. Sequence III represents a permanent shift to low or dry lake stands. By 4,000 cy BP, the lake earns rightfully its appellation of Dry Lake as indicated by a permanently contracted central basin. The similarity in ages of early Holocene lake level change across the greater region of Southern California suggests a similar external forcing - perhaps modulation of early Holocene storm activity by insolation (Kirby et al., 2007). The lake level records are less congruous for the mid-to-late Holocene across the region. Specifically for Dry Lake, it is not clear what caused the apparently rapid shift from a deep, early Holocene lake to a permanent shallow or dry lake by the mid-Holocene.

  2. Lake nutrient stoichiometry is less predictable than nutrient concentrations at regional and sub-continental scales.

    PubMed

    Collins, Sarah M; Oliver, Samantha K; Lapierre, Jean Francois; Stanley, Emily H; Jones, John R; Wagner, Tyler; Soranno, Patricia A

    2017-03-31

    Production in many ecosystems is co-limited by multiple elements. While a known suite of drivers associated with nutrient sources, nutrient transport, and internal processing controls concentrations of phosphorus (P) and nitrogen (N) in lakes, much less is known about whether the drivers of single nutrient concentrations can also explain spatial or temporal variation in lake N:P stoichiometry. Predicting stoichiometry might be more complex than predicting concentrations of individual elements because some drivers have similar relationships with N and P, leading to a weak relationship with their ratio. Further, the dominant controls on elemental concentrations likely vary across regions, resulting in context dependent relationships between drivers, lake nutrients and their ratios. Here, we examine whether known drivers of N and P concentrations can explain variation in N:P stoichiometry, and whether explaining variation in stoichiometry differs across regions. We examined drivers of N:P in ~2,700 lakes at a sub-continental scale and two large regions nested within the sub-continental study area that have contrasting ecological context, including differences in the dominant type of land cover (agriculture vs. forest). At the sub-continental scale, lake nutrient concentrations were correlated with nutrient loading and lake internal processing, but stoichiometry was only weakly correlated to drivers of lake nutrients. At the regional scale, drivers that explained variation in nutrients and stoichiometry differed between regions. In the Midwestern US region, dominated by agricultural land use, lake depth and the percentage of row crop agriculture were strong predictors of stoichiometry because only phosphorus was related to lake depth and only nitrogen was related to the percentage of row crop agriculture. In contrast, all drivers were related to N and P in similar ways in the Northeastern US region, leading to weak relationships between drivers and stoichiometry. Our

  3. Lake

    ERIC Educational Resources Information Center

    Wien, Carol Anne

    2008-01-01

    The lake is blue black and deep. It is a glaciated finger lake, clawed out of rock when ice retracted across Nova Scotia in a northerly direction during the last ice age. The lake is narrow, a little over a mile long, and deep, 90 to 190 feet in places according to local lore, off the charts in others. The author loves to swim there, with a sense…

  4. Contamination and Risk Assessment of Heavy Metals in Lake Bed Sediment of a Large Lake Scenic Area in China

    PubMed Central

    Wan, Li; Xu, Liang; Fu, Yongsheng

    2016-01-01

    The exposure of heavy metals to lake bed sediment of scenic areas may pose risks on aquatic ecosystems and human health, however very few studies on risk assessment have been reported for scenic areas. Accordingly, this study determined concentration levels, and assessed contamination characteristics and risks, of heavy metals in lake bed sediment of National Scenic Areas Songhuahu (NSAS) in China. The concentrations of Zn, Cr, Pb, Ni, and Cu were determined in 29 bed sediment samples. Results showed that the mean values of Zn, Cr, Pb, Ni, and Cu were 92.69, 90.73, 38.29, 46.77, and 49.44 mg/kg, respectively. Pearson correlation coefficients indicated that organic matter was a major factor influencing distribution of heavy metals. The results for enrichment factors indicated that contamination rates and anthropogenic inputs of single heavy metals decreased in the order Cu > Ni > Pb > Cr > Zn; results of Nemerow integrated pollution index suggested that 72.41% of sampling sites were exposed to low to moderately integrated pollution, and 27.59% of sampling sites were exposed to strongly integrated pollution. According to results for potential ecological risk index, ecological risks of single and all the heavy metals in bed sediment from all the sampling sites were low. Human risks were assessed with hazardous quotients, and the results suggested that exposure of heavy metals to bed sediment posed no or little risk to human health, and the pathway of ingestion significantly contributed to human health risks. PMID:27455296

  5. Regional economic impacts of water management alternatives: the case of Devils Lake, North Dakota, USA.

    PubMed

    Leistritz, F Larry; Leitch, Jay A; Bangsund, Dean A

    2002-12-01

    Devils Lake, located in a closed basin in northeastern North Dakota has over a century-long history of highly fluctuating water levels. The lake has risen nearly 25 feet (7.7 m) since 1993, more than doubling its surface area. Rising water levels have affected rural lands, transportation routes, and communities near the lake. In response to rising lake levels, Federal, state and local agencies have adopted a three-part approach to flood damage reduction, consisting of (1) upper basin water management to reduce the amount of water reaching the lake, (2) protection for structures and infrastructure if the lake continues to rise, and (3) developing an emergency outlet to release some lake water. The purpose of this study was to provide information about the net regional economic effects of a proposed emergency outlet for Devils Lake. An input-output model was used to estimate the regional economic effects of the outlet, under two scenarios: (1) the most likely future situation (MLS) and (2) a best case situation (BCS) (i.e., where the benefits from the outlet would be greatest), albeit an unlikely one. Regional economic effects of the outlet include effects on transportation (road and railroad construction), agriculture (land kept in production, returned to production sooner, or kept in production longer), residential relocations, and outlet construction expenditures. Effects are measured as changes in gross business volume (gross receipts) for various sectors, secondary employment, and local tax collections. The net regional economic effects of the proposed outlet would be relatively small, and consideration of these economic impacts would not strengthen the case for an outlet.

  6. Heavy metal contamination status and source apportionment in sediments of Songhua River Harbin region, Northeast China.

    PubMed

    Li, Ning; Tian, Yu; Zhang, Jun; Zuo, Wei; Zhan, Wei; Zhang, Jian

    2016-07-09

    The Songhua River represents one of the seven major river systems in China. It flows through Harbin city with 66 km long, locating in the northern China with a longer winter time. This paper aimed to study concentration distributions, stability, risk assessment, and source apportionment of heavy metals including chromium (Cr), cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As), copper (Cu), zinc (Zn), and nickel (Ni) in 11 selected sections of the Songhua River Harbin region. Results showed that Cr, Cd, Pb, Hg, and As exceeded their respective geochemical background values in sediments of most monitoring sections. Compared with other important rivers and lakes in China, Cr, Hg, Cd, and As pollutions in surface sediments were above medium level. Further analysis of chemical speciation indicated that Cr and As in surface sediments were relatively stable while Pb and Cd were easily bioavailable. Correlation analysis revealed sources of these metals except As might be identical. Pollution levels and ecological risks of heavy metals in surface sediments presented higher in the mainstream region (45° 47.0' N ~ 45° 53.3' N, 126° 37.0' E ~ 126° 42.1' E). Source apportionment found Hejiagou and Ashi River were the main contributors to metal pollution of this region. Thus, anthropogenic activities along the Hejiagou and Ashi River should be restricted in order to protect the Songhua River Harbin region from metal contamination.

  7. Land-cover changes in an urban lake watershed in a mega-city, Central China.

    PubMed

    Li, Yan; Zhao, Shuqing; Zhao, Kun; Xie, Ping; Fang, Jingyun

    2006-04-01

    Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity.

  8. Demarcation of Typhoon-induced Sedimentary Layers from Lake Records in Southeast China

    NASA Astrophysics Data System (ADS)

    Kandasamy, Selvaraj; Lin, Baozhi; Wang, Huawei; Liu, Qianqian; Lou, Jiann-Yuh; Liu, Zhifei; Chen, Chen-Tung Arthur

    2016-04-01

    Understanding the frequency and cyclicity of extreme events such as tropical storms, heat waves, floods and droughts in monsoon-governed Asia is crucial for the adaptation and mitigation of climate-driven troubles and post-event consequences. Such studies are also critical for the development of future climate-related policies, given that the loss of life and properties during such events in Asia are always many-folds higher than that of the effect of similar disasters in the developed world. Lakes located along the path of typhoons in East Asia may preserve an evidence of storm intensity, because an increased erosion in the confined catchment may increase the clastic sedimentation. Here we investigate ca. 90 cm-long sediment core retrieved from Tian Lake, a coastal island lake located off SE China, for sedimentological, radiometric and geochemical parameters, aiming to reconstruct the effect of past typhoons on the sedimentation history of the lake. We found 4-5 sand-dominated layers in between the regular fine sediments deposition and these sand layers show a close consistency with periods of intense typhoons in the instrumental record. Although the instrumental record suggests an average of 16 typhoons/year in the western North Pacific, the preservation of only 4-5 sand-dominated layers during the last ca. 100 years of accumulation in our core indicates that the sedimentation pattern in Tian Lake may be very sensitive to intense typhoons with category 3 and above. This study will attempt to compare our lacustrine records with the suitable instrumental and other proxy records for understanding mechanisms responsible for intense typhoons and related environmental changes in SE China in the past century.

  9. Isotopic evolution of saline lakes in the low-latitude and polar regions

    SciTech Connect

    Horita, Juske

    2009-01-01

    Isotopic fractionations associated with two primary processes (evaporation and freezing of water) are discussed, which are responsible for the formation and evolution of saline lakes in deserts from both low-latitude and the Polar regions. In an evaporative system, atmospheric parameters (humidity and isotopic composition of water vapor) have strong influence on the isotopic behavior of saline lakes, and in a freezing system, salinity build-up largely controls the extent of freezing and associated isotope fractionation. In both systems, salinity has a direct impact on the isotopic evolution of saline lakes. It is proposed that a steady-state terminal lake model with short-term hydrologic and environmental perturbations can serve as a useful framework for investigating both evaporative and freezing processes of perennial saline lakes. Through re-assessment of own work and literature data for saline lakes, it was demonstrated that effective uses of the isotope activity compositions of brines and salinity-chemistry data could reveal dynamic changes and evolution in the isotopic compositions of saline lakes in response to hydrologic and environmental changes. The residence time of isotopic water molecules in lakes determines the nature of responses in the isotopic compositions following perturbations in the water and isotope balances (e.g., dilution by inflow, water deficit by increased evaporation, and/ or reduction in inflow). The isotopic profiles of some saline lakes from the Polar regions show that they switched the two contrasting modes of operation between evaporative and freezing systems, in response to climate and hydrological changes in the past.

  10. Isotopic Evolution of Saline Lakes in the Low-Latitude and Polar Regions

    SciTech Connect

    Horita, Juske

    2009-01-01

    Isotopic fractionations associated with two primary processes (evaporation and freezing of water) are discussed, which are responsible for the formation and evolution of saline lakes in deserts from both low-latitude and the Polar regions. In an evaporative system, atmospheric parameters (humidity and isotopic composition of water vapor) have strong influence on the isotopic behavior of saline lakes, and in a freezing system, salinity build-up largely controls the extent of freezing and associated isotope fractionation. In both systems, salinity has a direct impact on the isotopic evolution of saline lakes. It is proposed that a steady-state 'terminal lake' model with short-term hydrologic and environmental perturbations can serve as a useful framework for investigating both evaporative and freezing processes of perennial saline lakes. Through re-assessment of own work and literature data for saline lakes, it was demonstrated that effective uses of the isotope activity compositions of brines and salinity-chemistry data could reveal dynamic changes and evolution in the isotopic compositions of saline lakes in response to hydrologic and environmental changes. The residence time of isotopic water molecules in lakes determines the nature of responses in the isotopic compositions following perturbations in the water and isotope balances (e.g., dilution by inflow, water deficit by increased evaporation, and/or reduction in inflow). The isotopic profiles of some saline lakes from the Polar regions show that they switched the two contrasting modes of operation between evaporative and freezing systems, in response to climate and hydrological changes in the past.

  11. Climate change and waterborne disease risk in the Great Lakes region of the U.S.

    PubMed

    Patz, Jonathan A; Vavrus, Stephen J; Uejio, Christopher K; McLellan, Sandra L

    2008-11-01

    Extremes of the hydrologic cycle will accompany global warming, causing precipitation intensity to increase, particularly in middle and high latitudes. During the twentieth century, the frequency of major storms has already increased, and the total precipitation increase over this time period has primarily come from the greater number of heavy events. The Great Lakes region is projected to experience a rise these extreme precipitation events. For southern Wisconsin, the precipitation rate of the 10 wettest days was simulated using a suite of seven global climate models from the UN Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. For each ranking, the precipitation rate of these very heavy events increases in the future. Overall, the models project that extreme precipitation events will become 10% to 40% stronger in southern Wisconsin, resulting in greater potential for flooding, and for the waterborne diseases that often accompany high discharge into Lake Michigan. Using 6.4 cm (2.5 in) of daily precipitation as the threshold for initiating combined sewer overflow into Lake Michigan, the frequency of these events is expected to rise by 50% to 120% by the end of this century. The combination of future thermal and hydrologic changes may affect the usability of recreational beaches. Chicago beach closures are dependent on the magnitude of recent precipitation (within the past 24 hours), lake temperature, and lake stage. Projected increases in heavy rainfall, warmer lake waters, and lowered lake levels would all be expected to contribute to beach contamination in the future. The Great Lakes serve as a drinking water source for more than 40 million people. Ongoing studies and past events illustrate a strong connection between rain events and the amount of pollutants entering the Great Lakes. Extreme precipitation under global warming projections may overwhelm the combined sewer systems and lead to overflow events that can threaten both human

  12. Simulating the water balance of the Aral Sea with a coupled regional climate-lake model

    USGS Publications Warehouse

    Small, E.E.; Sloan, L.C.; Hostetler, S.; Giorgi, F.

    1999-01-01

    Before coupled atmosphere-lake models can be used to study the response of large lake systems to climatic forcings, we must first evaluate how well they simulate the water balance and associated lake atmosphere interactions under present-day conditions. We evaluate the hydrology simulated by a lake model coupled to NCAR's regional climate model (RegCM2) in a study of the Aral Sea. The meteorological variables that are input to the lake model are simulated well by RegCM2. Simulated surface air temperatures closely match observed values, except during spring and fall when the simulated temperatures are too cold. The magnitude of precipitation is too high in the region surrounding the Aral Sea during summer and fall. On a yearly basis, RegCM2 produces a reasonable amount of runoff throughout the drainage basin. The lake model coupled to RegCM2 accurately simulates Aral Sea surface temperatures (SSTs). The lake model also simulates observed mid-winter ice fraction well, although the onset of ice growth occurs too late in the year and the ice melts too rapidly in the spring. The simulated annual evaporation from the Aral Sea is consistent with observed estimates; however, the simulated evaporation is greater than observed during summer and less than observed during winter. In a "stand-alone" lake model simulation, the simulated Aral Sea hydrology does not match observations as closely as in the coupled model experiment. These results suggest that a stand-alone lake model would not accurately simulate the hydrologic response of the Aral Sea to various forcings. Copyright 1999 by the American Geophysical Union.

  13. Empirical Relationships Between Watershed Attributes and Headwater Lake Chemistry in the Adirondack Region

    SciTech Connect

    Hunsaker, C.T.

    1987-01-01

    Surface water acidification may be caused or influenced by both natural watershed processes and anthropogenic actions. Empirical models and observational data can be useful for identifying watershed attributes or processes that require further research or that should be considered in the development of process models. This study focuses on the Adirondack region of New York and has two purposes: to (1) develop empirical models that can be used to assess the chemical status of lakes for which no chemistry data exist and (2) determine on a regional scale watershed attributes that account for variability in lake pH and acid-neutralizing capacity (ANC). Headwater lakes, rather than lakes linked to upstream lakes, were selected for initial analysis. The Adirondacks Watershed Data Base (AWDB), part of the Acid Deposition Data Network maintained at Oak Ridge National Laboratory (ORNL), integrates data on physiography, bedrock, soils, land cover, wetlands, disturbances, beaver activity, land use, and atmospheric deposition with the water chemistry and morphology for the watersheds of 463 headwater lakes. The AWD8 facilitates both geographic display and statistical analysis of the data. The report, An Adirondack Watershed Data Base: Attribute and Mapping Information for Regional Acidic Deposition Studies (ORNL/TM--10144), describes the AWDB. Both bivariate (correlations and Wilcoxon and Kruskal-Wallis tests) and multivariate analyses were performed. Fifty-seven watershed attributes were selected as input variables to multiple linear regression and discriminant analysis. For model development -200 lakes for which pH and ANC data exist were randomly subdivided into a specification and a verification data set. Several indices were used to select models for predicting lake pH (31 variables) and ANC (27 variables). Twenty-five variables are common to the pH and ANC models: four lake morphology, nine soil/geology, eight land cover, three disturbance, and one watershed aspect. An

  14. A Regional Categorization for "New-Type Urbanization" in China.

    PubMed

    Fang, Chuanglin; Ma, Haitao; Wang, Jing

    2015-01-01

    Regional differences in the character of urbanization in China are substantial. The promotion of what has been termed "new-type urbanization" cannot, as a result of these regional differences, be expected to follow a universal approach--rather, such a development must objectively adhere to locational and category-specific principles and adopt differentiated urbanization development models. Regional categorization is often used in geography, but is rarely deployed in research addressing human and social problems relating to urbanization. In March 2014, China published the National New-type Urbanization Plan (2014-2020), which calls for the scientific and reasonable planning of "new-type urbanization," and appropriate regional categorizations are urgently needed in order to guide this reform. Responding to this challenge, this research engaged in the design of a "dominantly quantitative analysis, qualitatively supplemented" method in order to divide China into 5 main regions and 47 sub-regions in terms of new-type urbanization. The paper discusses the features and key problems of each region. This study introduces a new method for regional categorization, thereby remedying the lack of regional categorization in relation to "new-type urbanization" in China, and ultimately promoting the development of regional categorization in the humanities as a valuable reference for healthy and sustainable Chinese urbanization.

  15. Fluorescent components and spatial patterns of chromophoric dissolved organic matters in Lake Taihu, a large shallow eutrophic lake in China.

    PubMed

    Yao, Bo; Hu, Chunming; Liu, Qingquan

    2016-11-01

    Water samples at both surface and bottom layers were taken from 102 sites in Lake Taihu to study the fluorescent components and spatial patterns of chromophoric dissolved organic matters (CDOM). Three-dimensional excitation-emission matrix data obtained from the samples were analyzed by parallel factor approach in which four humic-like and two protein-like fluorescent components (named C1-C6) were identified. The results showed that fluorescence intensities were higher in the northern and western lake regions, and notable declines of fluorescence maxima (F max) were observed from the northwest to the center and then to the southeast of the lake. Calculated biological index (BIX) values ranged from 0.88 to 1.44 and humification index (HIX) values from 0.64 to 3.37 for all the samples. The spatial variations of BIX and HIX values suggested stronger allochthonous CDOM characteristics in Zhushan Bay and the western area and autochthonous characteristics in the southern and eastern areas. Vertically, the average F max value of the surface samples was about 6 % less than that of the bottom samples, but noticeable variations existed among different sampling sites and components. These distribution characteristics of CDOM were mainly attributed to the spatial heterogeneity of sources and wind-induced transportation process. Interestingly, the C6 component (Exmax/Emmax = 250/455 nm) seemed to be unique in samples from Zhushan Bay and probably resulted from the discharge of the Taige River. Therefore, it could be used as an indicator of point-source discharge and a tracer to study the fate of CDOM in the lake.

  16. China, The Regional Hegemon with Global Reach

    DTIC Science & Technology

    2011-03-07

    courtship of cash-strapped countries such as Spain, pledging to buy their bonds and expand business ties.28 In January 2011, Vice Prime Minister Li...Jacques, When China Rules the World (New York, NY: Penguin , 2009), 347. 80 Ibid., 6. 81 Ibid., 348. 82 Evan Medeiros, China’s International Behavior

  17. Learning about War and Peace in the Great Lakes Region of Africa

    ERIC Educational Resources Information Center

    Bird, Lyndsay

    2007-01-01

    Two-thirds of the world's conflicts are in Africa. In particular, the Great Lakes region (Rwanda, Burundi, Democratic Republic of Congo, Uganda and Tanzania) continues to see conflicts that are complex, extreme and seemingly intractable. By exploring the narrative experiences of those most affected by the conflicts in the region--specifically…

  18. Significant seasonal variations of microbial community in an acid mine drainage lake in Anhui Province, China.

    PubMed

    Hao, Chunbo; Wei, Pengfei; Pei, Lixin; Du, Zerui; Zhang, Yi; Lu, Yanchun; Dong, Hailiang

    2017-04-01

    Acid mine drainage (AMD),characterized by strong acidity and high metal concentrations, generates from the oxidative dissolution of metal sulfides, and acidophiles can accelerate the process significantly. Despite extensive research in microbial diversity and community composition, little is known about seasonal variations of microbial community structure (especially micro eukaryotes) in response to environmental conditions in AMD ecosystem. To this end, AMD samples were collected from Nanshan AMD lake, Anhui Province, China, over a full seasonal cycle from 2013 to 2014, and water chemistry and microbial composition were studied. pH of lake water was stable (∼3.0) across the sampling period, while the concentrations of ions varied dramatically. The highest metal concentrations in the lake were found for Mg and Al, not commonly found Fe. Unexpectedly, ultrahigh concentration of chlorophyll a was measured in the extremely acidic lake, reaching 226.43-280.95 μg/L in winter, even higher than those in most eutrophic freshwater lakes. Both prokaryotic and eukaryotic communities showed a strong seasonal variation. Among the prokaryotes, "Ferrovum", a chemolithotrophic iron-oxidizing bacterium was predominant in most sampling seasons, although it was a minor member prior to September, 2012. Fe(2+) was the initial geochemical factor that drove the variation of the prokaryotic community. The eukaryotic community was simple but varied more drastically than the prokaryotic community. Photoautotrophic algae (primary producers) formed a food web with protozoa or flagellate (top consumers) across all four seasons, and temperature appeared to be responsible for the observed seasonal variation. Ochromonas and Chlamydomonas (responsible for high algal bloom in winter) occurred in autumn/summer and winter/spring seasons, respectively, because of their distinct growth temperatures. The closest phylogenetic relationship between Chlamydomonas species in the lake and those in Arctic

  19. Detritus Quality Controls Macrophyte Decomposition under Different Nutrient Concentrations in a Eutrophic Shallow Lake, North China

    PubMed Central

    Li, Xia; Cui, Baoshan; Yang, Qichun; Tian, Hanqin; Lan, Yan; Wang, Tingting; Han, Zhen

    2012-01-01

    Macrophyte decomposition is important for carbon and nutrient cycling in lake ecosystems. Currently, little is known about how this process responds to detritus quality and water nutrient conditions in eutrophic shallow lakes in which incomplete decomposition of detritus accelerates the lake terrestrialization process. In this study, we investigated the effects of detritus quality and water nutrient concentrations on macrophyte decomposition in Lake Baiyangdian, China, by analyzing the decomposition of three major aquatic plants at three sites with different pollution intensities (low, medium, and high pollution sites). Detritus quality refers to detritus nutrient contents as well as C∶N, C∶P, and N∶P mass ratios in this study. Effects of detritus mixtures were tested by combining pairs of representative macrophytes at ratios of 75∶25, 50∶50 and 25∶75 (mass basis). The results indicate that the influence of species types on decomposition was stronger than that of site conditions. Correlation analysis showed that mass losses at the end of the experimental period were significantly controlled by initial detritus chemistry, especially by the initial phosphorus (P) content, carbon to nitrogen (C∶N), and carbon to phosphorus (C∶P) mass ratios in the detritus. The decomposition processes were also influenced by water chemistry. The NO3-N and NH4-N concentrations in the lake water retarded detritus mass loss at the low and high pollution sites, respectively. Net P mineralization in detritus was observed at all sites and detritus P release at the high pollution site was slower than at the other two sites. Nonadditive effects of mixtures tended to be species specific due to the different nutrient contents in each species. Results suggest that the nonadditive effects varied significantly among different sites, indicating that interactions between the detritus quality in species mixtures and site water chemistry may be another driver controlling decomposition

  20. A Lake Sediment Record of Climate Change and Human-Environment Interactions in Southwestern China

    NASA Astrophysics Data System (ADS)

    Hillman, A.; Abbott, M.; Yu, J.; Steinman, B. A.

    2012-12-01

    The delivery of precipitation to southwestern China is largely through monsoon circulation which has evolved with changing insolation during the Holocene. Additionally, southwestern China has a long history of human activity including mining, metallurgy, agriculture, and pollution. Here, high-resolution sampling of a sediment core from Lake Xing Yun in the Yunnan Province (24°10'N, 102°46'E), a drought sensitive lake that behaves as a closed basin system, provides a sub-decadal record of changing climate and human activity in the late Holocene. We use δ18O and δ13C measurements of authigenic carbonate precipitated from the lake water, magnetic susceptibility values, and hydrologic mass balance models to document the timing, direction, and magnitude of moisture changes associated with variations in monsoon strength. We also use δ13C and δ15N measurements on organic matter, carbon to nitrogen ratios, and sediment trace metal concentrations to assess the impact of human activity on the Xing Yun watershed. The 2,500 year record highlights several transition periods related to both human and climate forcing. The rise of intensive irrigation of the lake associated with agriculture occurs at 900 AD, coincident with the rise of metallurgy and mining activities. The period from 1200 to 1360 AD is marked by an abrupt decrease in δ18O values indicating that lake-level rose at this time. We attribute this to a shifting demographic change associated with political upheaval, which is supported by the leveling off of trace metal concentrations and the stagnation of metallurgy and mining activities. The most pronounced feature of the record is a rapid transition to substantially lower lake levels that persisted from 1360-1850 AD. This can be attributed to the return of dramatic human modification to the watershed and changing monsoon strength associated with the Little Ice Age. Using hydrologic mass balance models we are able to quantify the change that can be ascribed to

  1. Climatic characteristics and regionalization of fogs in China

    NASA Astrophysics Data System (ADS)

    Hao, T. Y.; Chen, S. C.; Han, S. Q.; Shan, X. L.; Meng, L. H.

    2017-01-01

    Using trend coefficient method, vector analysis method, and monitored meteorological data across China, climatic characteristics and spatial pattern of fogs in China were investigated. The results show that most fogs occur in southeastern China. Thin fogs usually occur in fog-rare regions and dense fogs take place in fog-prone regions. The number of annual fog days in most regions of China exhibits a decreasing trend from 1980 to 2010. It also found that the regions with more fog days correspond to the lower concentration degree of fogs, and vice versa. In terms of the national scale, the concentration periods of fogs are mainly in November, December, and January in China. We further classified the occurrence frequencies of fogs into five spatial distribution patterns over a single year according to the spatial distribution characteristics of fogs occurrence frequencies of 36 dekads, namely, a whole year can be correspondingly divided into five phases. Based on this, multi-year average fog-prone regions in the five phases are obtained. Our results also identify the high incidence periods of fogs in different fog-prone regions.

  2. Occurrence of antibiotics and their impacts to primary productivity in fishponds around Tai Lake, China.

    PubMed

    Song, Chao; Zhang, Cong; Fan, Limin; Qiu, Liping; Wu, Wei; Meng, Shunlong; Hu, Gengdong; Kamira, Barry; Chen, Jiazhang

    2016-10-01

    Antibiotics are widely used to improve the health and yields of farmed animals, including fish, but their use is accompanied by undesirable ecological effects. Relatively little is known about the water-body burden of antibiotics and their influence on primary productivity in aquaculture ecosystem. In this study, antibiotics usage within 24 fishponds, covering 4 areas, sampled 5 times, and having 5 fish species, was investigated surrounding Tai Lake in China. The study analyzed 15 antibiotics (including 5 sulfonamides, 2 quinolones, 3 β-lactams, 3 tetracyclines, 1 amphenicol, and 1 macrolide), and all of them were detected in water samples, with a detection frequency of 2-60%. Sulfonamides were the most prevalent, and concentrations of sulfamethoxazole, sulfamonomethoxine, and florfenicol being over 2000 ng L(-1) in some samples, while the other antibiotics levels ranged from ND (no detection) to 551.18 ng L(-1). Significant differences were observed in antibiotic burden among different regions for total antibiotics, sulfonamides, quinolones, and amphenicols; among time points for quinolones, β-lactams, and tetracyclines; and among species for quinolones and macrolides. Furthermore, basing on the risk quotient (RQ) method, the assessment revealed that florfenicol was of highest risk to algae with RQ values exceeding 0.1, while macrolide erythromycin posed the second highest risk. The partial correlation coefficient between total antibiotics and chlorophyll (a) was -0.035 that clearly indicated total antibiotics were detrimental to green algae growth, while the nutrient input and other physical - chemical factors were much more beneficial. Overall, holistic far-reaching measures of antibiotics control are recommended to preserve aquaculture ecosystem health.

  3. Identification of nitrogen sources to four small lakes in the agricultural region of Khorezm, Uzbekistan

    USGS Publications Warehouse

    Shanafield, M.; Rosen, M.; Saito, L.; Chandra, S.; Lamers, J.; Nishonov, Bakhriddin

    2010-01-01

    Pollution of inland waters by agricultural land use is a concern in many areas of the world, and especially in arid regions, where water resources are inherently scarce. This study used physical and chemical water quality and stable nitrogen isotope (δ15N) measurements from zooplankton to examine nitrogen (N) sources and concentrations in four small lakes of Khorezm, Uzbekistan, an arid, highly agricultural region, which is part of the environmentally-impacted Aral Sea Basin. During the 2-year study period, ammonium concentrations were the highest dissolved inorganic N species in all lakes, with a maximum of 3.00 mg N l−1 and an average concentration of 0.62 mg N l−1. Nitrate levels were low, with a maximum concentration of 0.46 mg N l−1 and an average of 0.05 mg N l−1 for all four lakes. The limited zooplankton δ15N values did not correlate with the high loads of synthetic fertilizer applied to local croplands during summer months. These results suggest that the N cycles in these lakes may be more influenced by regional dynamics than agricultural activity in the immediate surroundings. The Amu-Darya River, which provides the main source of irrigation water to the region, was identified as a possible source of the primary N input to the lakes.

  4. Monitoring variations of inland lakes in the arid region of Central Asia

    NASA Astrophysics Data System (ADS)

    Bai, Jie; Chen, Xi; Yang, Liao; Fang, Hui

    2012-06-01

    Inland lakes are the major surface water resource in the arid regions of Central Asia. Therefore, the surface area changes in inland lakes have been a sensitive indicator of climate changes and human activities, and have often been the focus of ecological and environmental research. This study aimed to monitor the changes in surface area of nine major lakes over a 32-year period. The water body was extracted from MSS images from the mid-1970s, TM images from the early 1990s, ETM + images in the late 1990s, and TM images in 2007. The results indicated that the total surface area of these nine lakes had decreased over time to 50.38% of the area, from 91402.06 km2 in 1975 to 46049.23 km2 in 2007. As the surface area of lakes in the western part of Central Asia was larger than that in the eastern part, the shrinking trend of lake area was more significant in the west than in the east. There was a varied reduction of closed lakes in flat regions. The most substantial decrease was in the surface area of closed lakes in flat regions. Most significantly, the area of the Aral Sea was reduced by 75.7% from its original area in 1975. The area of alpine lakes remained relatively stable; the change in surface area was less than 0.7% during the period 1975-2007. The area change in opened lakes with outlets was notably different from the other two types. The area of Zaysan had increased sharply by 5.85%, and that of Bosten had decreased by 9.1%. Sasykkol had hardly any changes in this period. Due to global climate warming, vapor transfer to the south via westerly winds had been blocked, resulting in a decrease of much-needed precipitation in the western parts of Turkmenistan, Uzbekistan, and Kazakhstan between 1970 and 2000. The decrease in precipitation and the increase in water consumption for agricultural irrigation resulted in the decrease of river runoff. Consequently, the area of inland lakes in Central Asia shrank over the past 32 years.

  5. Use of wetlands under USEPA's (Environmental Protection Agency's) Region 5 Clean Lakes Program. Master's thesis

    SciTech Connect

    Landers, J.C.

    1989-05-01

    The EPA's Region V Clean Lakes Program uses several wetlands for controlling degradation of publicly owned, freshwater lakes. The study seeks to determine if the objectives of the Clean Lakes Program are being met by this use of wetlands, and if appropriate institutional arrangements and management techniques are being implemented to manage the wetlands. Conclusions regarding Revion V's use and management of wetlands include: wetland projects are not being monitored adequately for effectiveness and potential negative impacts on ecosystems; other mechanisms which may help to protect wetlands are being employed; management of most wetland projects is decentralized appropriately; most of the wetland projects provide for adequate short-term mass balance studies, prior sedimentation, plant species diversity, water level, retention time, uniform flow of water, and upland pollutant management; and existing evidence suggests that the Clean Lakes wetland projects are instrumental in meeting Program goals and objectives. Based on these conclusions several recommendations for improving wetlands management are reviewed.

  6. Impact of lake-river connectivity and interflow on the Canadian RCM simulated regional climate and hydrology for Northeast Canada

    NASA Astrophysics Data System (ADS)

    Huziy, O.; Sushama, L.

    2017-02-01

    Lakes affect regional climate by modulating surface albedo, surface energy, and moisture budgets. This is especially important for regions such as Northeast Canada with approximately 10 % of the landmass covered by lakes, wetlands and rivers. From the regional hydrology perspective, interactions between lakes and rivers are important as streamflow patterns can be significantly modified by lake storage, and similarly lake levels can be modified by streamflows. In this study, using a suite of experiments performed with the fifth generation Canadian Regional Climate Model (CRCM5) driven by the European Centre for Medium range Weather Forecasting ERA40 reanalysis data at the lateral boundaries for the 1979-2010 period, lake-river-atmosphere interactions and their impact on the regional climate/hydrology of north-east Canada are assessed. In these CRCM5 simulations, a one-dimensional lake model represents lakes, while the rivers are modeled using a distributed routing scheme, and one of the simulations includes interflow, i.e. lateral flow of water in the soil layers. Comparison of CRCM5 simulations with and without lakes suggests significant differences in winter/summer precipitation and winter temperature for the study region. CRCM5 simulations performed with and without lake-river interactions suggest improved representation of streamflows when lake storage and routing are taken into account. Adding the interflow process leads to increased streamflows during summer and fall seasons for the majority of the rivers, causing modest changes to land-atmosphere interactions via modified soil moisture. The impact of interflow on streamflow, obtained in this study, is comparable to the impact of lake-atmosphere interactions on streamflows. This study clearly demonstrates the need for realistic representation of lake-river interactions in regional climate models for realistic simulation of regional hydrology, particularly streamflows.

  7. Temporal and spatial variations in phytoplankton: correlations with environmental factors in Shengjin Lake, China.

    PubMed

    Wang, Lan; Wang, Chao; Deng, Daogui; Zhao, Xiuxia; Zhou, Zhongze

    2015-09-01

    Temporal and spatial variations in the phytoplankton community and environmental variables were investigated from February to July 2014, in the upper lake of Shengjin Lake, China. We identified 192 species of phytoplankton belonging to 8 phyla and 84 genera, of which 46.4% of Chlorophyta, 29.2% of Bacillariophyta, and 12.5% of Cyanophyta. There were 14 predominant species. Marked temporal and spatial variations were observed in the phytoplankton community. The total abundance of phytoplankton ranged from 3.66 × 10(5) to 867.93 × 10(5) cells/L and total biomass ranging from 0.40 to 20.89 mg/L. The Shannon-Wiener diversity index varied from 3.50 to 8.35 with an average of 5.58, revealing high biodiversity in the phytoplankton community. There were substantial temporal changes in the dominant species, from Bacillariophyta and Cryptophyta to Cyanophyta and Chlorophyta. Phytoplankton biomass and abundance showed a similar increasing trend from February to July. Pearson correlations and Redundancy analysis revealed that the most significant environmental factors influencing phytoplankton community were water temperature (T), transparency (SD), and nutrient concentration. The positive correlation between the key water bird areas and phytoplankton biomass indicated that the droppings of wintering water birds had an important influence on the phytoplankton community in the upper lake of Shengjin Lake.

  8. Distinct Factors Shape Aquatic and Sedimentary Microbial Community Structures in the Lakes of Western China

    PubMed Central

    Yang, Jian; Jiang, Hongchen; Wu, Geng; Liu, Wen; Zhang, Guojing

    2016-01-01

    Little is known about the relative importance of spatial and environmental factors to structuring aquatic and sedimentary microbial biogeography in lakes. Here, we investigated the microbial community composition (MCC) of the water (n = 35) and sediment (n = 35) samples from 16 lakes in western China (salinity: freshwater to salt saturation; pairwise geographical distance: 9–2027 km) using high-throughput sequencing and evaluated the relative importance of spatial and environmental factors to microbial (including total, abundant, and rare) distributions. Our results showed that spatial factors were more important than environmental factors in shaping the biogeography of aquatic and sedimentary microbial communities in the studied lakes, and spatial factors on abundant microbial community was stronger than that on the total/rare microbial communities. Moreover, sedimentary rare MCC might be more sensitive to environmental factors than its aquatic counterpart. Such different biogeography responses of total, abundant, and rare communities to environmental and spatial factors could be ascribed to different physiochemical properties between water and sediment. Collectively, this study expands our understanding of factors shaping microbial biogeography of total, abundant, and rare communities between waters and sediments of lakes. PMID:27877171

  9. Microalga Euglena as a bioindicator for testing genotoxic potentials of organic pollutants in Taihu Lake, China.

    PubMed

    Li, Mei; Gao, Xiangyu; Wu, Bing; Qian, Xin; Giesy, John P; Cui, Yibin

    2014-05-01

    The microalga Euglena was selected as a bioindicator for determining genotoxicity potencies of organic pollutants in Meiliang Bay of Taihu Lake, Jiangsu, China among seasons in 2008. Several methods, including the comet assay to determine breaks in DNA and quantification of antioxidant enzymes were applied to characterize genotoxic effects of organic extracts of water from Taihu Lake on the flagellated, microalga Euglena gracilis. Contents of photosynthetic pigments, including Chl a, Chl b and carotenoid pigments were inversely proportion to concentrations of organic extracts to which E. gracilis was exposed. Organic extracts of Taihu Lake water also affected activities of superoxide dismutase (SOD) and peroxidase (POD) of E. gracilis. There were no statistically significant differences in SOD activities among seasons except in June but significant differences in POD activities were observed among all seasons. The metrics of DNA fragmentation in the alkaline unwinding assay (Comet assay), olive tail moment (OTM) and tail moment (TM), used as measurement endpoints during the genotoxicity assay were both greater when E. gracilis was exposed to organic of water collected from Taihu Lake among four seasons. It is indicated that the comet assay was useful for determining effects of constituents of organic extracts of water on E. gracilis and this assay was effective as an early warning to organic pollutants.

  10. Simulation of Lake Victoria Circulation Patterns Using the Regional Ocean Modeling System (ROMS)

    PubMed Central

    Sigurdsson, Sven; Tomasson, Tumi; Taabu-Munyaho, Anthony; Sitoki, Lewis; Stefansson, Gunnar

    2016-01-01

    Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather conditions on diel, seasonal and annual scales. However, information on water temperature and circulation in the lake is limited in space and time. We use a Regional Oceanographic Model System (ROMS) to simulate these processes from 1st January 2000 to 31st December 2014. The model is based on real bathymetry, river runoff and atmospheric forcing data using the bulk flux algorithm. Simulations show that the water column exhibits annual cycles of thermo-stratification (September–May) and mixing (June–August). Surface water currents take different patterns ranging from a lake-wide northward flow to gyres that vary in size and number. An under flow exists that leads to the formation of upwelling and downwelling regions. Current velocities are highest at the center of the lake and on the western inshore waters indicating enhanced water circulation in those areas. However, there is little exchange of water between the major gulfs (especially Nyanza) and the open lake, a factor that could be responsible for the different water quality reported in those regions. Findings of the present study enhance understanding of the physical processes (temperature and currents) that have an effect on diel, seasonal, and annual variations in stratification, vertical mixing, inshore—offshore exchanges and fluxes of nutrients that ultimately influence the biotic distribution and trophic structure. For instance information on areas/timing of upwelling and vertical mixing obtained from this study will help predict locations/seasons of high primary production and ultimately fisheries productivity in Lake Victoria. PMID:27030983

  11. Simulation of Lake Victoria Circulation Patterns Using the Regional Ocean Modeling System (ROMS).

    PubMed

    Nyamweya, Chrispine; Desjardins, Christopher; Sigurdsson, Sven; Tomasson, Tumi; Taabu-Munyaho, Anthony; Sitoki, Lewis; Stefansson, Gunnar

    2016-01-01

    Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather conditions on diel, seasonal and annual scales. However, information on water temperature and circulation in the lake is limited in space and time. We use a Regional Oceanographic Model System (ROMS) to simulate these processes from 1st January 2000 to 31st December 2014. The model is based on real bathymetry, river runoff and atmospheric forcing data using the bulk flux algorithm. Simulations show that the water column exhibits annual cycles of thermo-stratification (September-May) and mixing (June-August). Surface water currents take different patterns ranging from a lake-wide northward flow to gyres that vary in size and number. An under flow exists that leads to the formation of upwelling and downwelling regions. Current velocities are highest at the center of the lake and on the western inshore waters indicating enhanced water circulation in those areas. However, there is little exchange of water between the major gulfs (especially Nyanza) and the open lake, a factor that could be responsible for the different water quality reported in those regions. Findings of the present study enhance understanding of the physical processes (temperature and currents) that have an effect on diel, seasonal, and annual variations in stratification, vertical mixing, inshore-offshore exchanges and fluxes of nutrients that ultimately influence the biotic distribution and trophic structure. For instance information on areas/timing of upwelling and vertical mixing obtained from this study will help predict locations/seasons of high primary production and ultimately fisheries productivity in Lake Victoria.

  12. Using a Coupled Lake Model with WRF to Improve High-Resolution Regional Climate Simulations

    NASA Astrophysics Data System (ADS)

    Mallard, M.; Bullock, R.; Nolte, C. G.; Alapaty, K.; Otte, T.; Gula, J.

    2012-12-01

    Lakes can play a significant role in regional climate by modifying air masses through fluxes of heat and moisture and by modulating inland extremes in temperature. Representing these effects becomes more important as regional climate modeling efforts employ finer grid spacing in order to simulate smaller scales. The Weather Research and Forecasting (WRF) model does not simulate lakes explicitly. Instead, lake points are treated as ocean points, with sea surface temperatures (SSTs) interpolated from the nearest neighboring ocean point in the driving coarse-scale fields. This can result in substantial errors for inland lakes such as the Great Lakes. Although prescribed lake surface temperatures (LSTs) can be used for retrospective modeling applications, this may not be desirable for applications involving downscaling future climate scenarios from a global climate model (GCM). In such downscaling simulations, lakes that impact the regional climate in the area of interest may not be resolved by the coarser global input fields. Explicitly simulating the LST would allow WRF to better represent interannual variability in regions significantly affected by lakes, and the influence of such variability on temperature and precipitation patterns. Therefore, coupling a lake model to WRF may lead to more reliable assessments of the impacts of extreme events on human health and the environment. We employ a version of WRF coupled to the Freshwater Lake model, FLake (Gula and Peltier 2012). FLake is a 1D bulk lake model which provides updated LSTs and ice coverage throughout the integration. This two-layer model uses a temperature-depth profile which includes a homogeneous mixed layer at the surface and a thermocline below. The shape of the thermocline is assumed, based on past theoretical and observational studies. Therefore, additional variables required for FLake to run are minimal, and it does not require tuning for individual lakes. These characteristics are advantageous for a

  13. Lake Vanda: A sentinel for climate change in the McMurdo Sound Region of Antarctica

    NASA Astrophysics Data System (ADS)

    Castendyk, Devin N.; Obryk, Maciej K.; Leidman, Sasha Z.; Gooseff, Michael; Hawes, Ian

    2016-09-01

    Lake Vanda is a perennially ice-covered, meromictic, endorheic lake located in the McMurdo Dry Valleys of Antarctica, and an exceptional sentinel of climate change within the region. Lake levels rose 15 m over the past 68 years in response to climate-driven variability in ice-cover sublimation, meltwater production, and annual discharge of the Onyx River, the main source of water to the lake. Evidence from a new bathymetric map and water balance model combined with annual growth laminations in benthic mats suggest that the most recent filling trend began abruptly 80 years ago, in the early 1930s. This change increased lake volume by > 50%, triggered the formation of a new, upper, thermohaline convection cell, and cooled the lower convection cell by at least 2 °C and the bottom-most waters by at > 4 °C. Additionally, the depth of the deep chlorophyll a maximum rose by > 2 m, and deep-growing benthic algal mats declined while shallow benthic mats colonized freshly inundated areas. We attribute changes in hydrology to regional variations in air flow related to the strength and position of the Amundsen Sea Low (ASL) pressure system which have increased the frequency of down-valley, föhn winds associated with surface air temperature warming in the McMurdo Dry Valleys. The ASL has also been implicated in the recent warming of the Antarctic Peninsula, and provides a common link for climate-related change on opposite sides of the continent. If this trend persists, Lake Vanda should continue to rise and cool over the next 200 years until a new equilibrium lake level is achieved. Most likely, future lake rise will lead to isothermal conditions not conducive to thermohaline convection, resulting in a drastically different physical, biogeochemical, and biological structure than observed today.

  14. Petrologic considerations for hot dry rock geothermal site selection in the Clear Lake Region, California

    SciTech Connect

    Stimac, J.; Goff, F. ); Hearn, B.C. Jr. )

    1992-01-01

    The Clear Lake area is well known for anomalous heat flow, thermal springs, hydrothermal mineral deposits, and Quaternary volcanism. These factors, along with the apparent lack of a large reservoir of geothermal fluid north of Collayomi fault make the Clear Lake area an attractive target for hot dry rock (HDR) geothermal development. Petrologic considerations provide some constraints on site selection for HDR development. Spatial and temporal trends in volcanism in the Coast Ranges indicate that magmatism has migrated to the north with time, paralleling passage of the Mendocino triple junction and propagation of the San Andreas fault. Volcanism in the region may have resulted from upwelling of hot asthenosphere along the southern margin of the subducted segment of the Gorda plate. Spatial and temporal trends of volcanism within the Clear Lake volcanic field are similar to larger-scale trends of Neogene volcanism in the Cost Ranges. Volcanism (especially for silicic compositions) shows a general migration to the north over the {approximately}2 Ma history of the field, with the youngest two silicic centers located at Mt. Konocti and Borax Lake. The Mt. Konocti system (active from {approximately} 0.6 to 0.3 Ma) was large and long-lived, whereas the Borax Lake system is much smaller but younger (0.09 Ma). Remnants of silicic magma bodies under Mt. Konocti may be in the latter stages of cooling, whereas a magma body centered under Borax Lake may be in the early stages of development. The existence of an upper crustal silicic magma body of under Borax Lake has yet to be demonstrated by passive geophysics, however, subsurface temperatures in the area as high (> 200{degrees}C at 2000 m) as those beneath the Mt. Konocti area. Based on petrologic considerations alone, the Mt. Konocti-Borax Lake area appears to be the most logical choice for HDR geothermal development in the region.

  15. Spatial distribution of penetration depth in Taihu Lake (China) during spring and autumn

    NASA Astrophysics Data System (ADS)

    Zhao, Qiaohua; Wei, Yingzhu; Ouyang, Xiaoran

    2013-07-01

    In the context of remote sensing, sunlight penetration depth is the depth above which 90% of the diffusely reflected irradiance from a water body surface originates. Model algorithms to simulate water quality variables such as chlorophyll a, dissolved organic matter, suspended matter, and Secchi depth are sensitive to the variations of this variable. The penetration depth for Taihu Lake in China, a shallow and turbid lake, was calculated by using a multiple scattering model, and in situ optical measurements were carried out during May and October 2010. The results show that: 1) the penetration depth generally increased from west to east during spring and from southeast to northwest during autumn, reflecting the prevailing wind direction and; 2) there was strong dependence of the penetration depth on the concentration of suspended matter.

  16. Residues, Sources and Potential Biological Risk of Organochlorine Pesticides in Surface Sediments of Qiandao Lake, China.

    PubMed

    Yang, Huayun; Zhou, Shanshan; Li, Weidong; Liu, Qi; Tu, Yunjie

    2015-10-01

    Sediment samples were analyzed to comprehensively characterize the concentrations, distribution, possible sources and potential biological risk of organochlorine pesticides in Qiandao Lake, China. Concentrations of sumHCH and sumDDT in sediments ranged from 0.03 to 5.75 ng/g dry weight and not detected to 14.39 ng/g dry weight. The predominant β-HCH and the α-HCH/γ-HCH ratios indicated that the residues of HCHs were derived not only from historical technical HCH use but also from additional usage of lindane. Ratios of o,p'-DDT/p,p'-DDT and DDD/DDE suggested that both dicofol-type DDT and technical DDT applications may be present in most study areas. Additionally, based on two sediment quality guidelines, γ-HCH, o,p'-DDT and p,p'-DDT could be the main organochlorine pesticides species of ecotoxicological concern in Qiandao Lake.

  17. Effects of young poplar plantations on understory plant diversity in the Dongting Lake wetlands, China

    PubMed Central

    Li, Youzhi; Chen, Xinsheng; Xie, Yonghong; Li, Xu; Li, Feng; Hou, Zhiyong

    2014-01-01

    This study evaluated the effects of young poplar plantations on understory plant diversity in the Dongting Lake wetlands, China. Poplar plantations resulted in a higher species number and Shannon's diversity. Species compositions were different between areas with poplar and reed populations: a lower ratio of hygrophytes but a higher ratio of mesophytes, and a higher ratio of heliophytes but a lower ratio of neutrophilous or shade plants in poplar areas compared to reed areas. Poplar plantations supported a higher ratio of ligneous plants in the entire Dongting Lake area, but there was no difference in the monitored plots. Unlike reedy areas, poplar plantations had higher light availability but lower soil water content during the growing seasons. These data suggest that young poplar plantations generally increased species richness and plant diversity, but significantly changed species composition due to the reduced soil water and increased light availability. PMID:25208975

  18. Holocene environmental fluctuations of Lake Bosten (Xinjiang, China) inferred from ostracods and stable isotopes

    NASA Astrophysics Data System (ADS)

    Mischke, S.

    2003-04-01

    Lake Bosten is an oligohaline lake in an intermontane basin of the Tianshan Mountains in northwestern China. The open-basin lake receives water from a large catchment area (56,000 km2) with the Kaidu River as its main tributary. A core of 9.25 m length was drilled at 6.25 m water depth in the southwestern part of the lake near the Kaidu river inflow. Sediments of the core contain authigenic carbonate materials, including calcitic shells of ostracods, charophyte-oogonia and stem incrustations. Five AMS-dating results provided the base to establish the chronology of the core which extends back to about 8.4 cal. ka BP. The majority of the ostracod taxa from the core may be classified into two different groups comprising littoral taxa (Cyclocypris ovum, Cypridopsis vidua, Darwinula stevensoni, Fabaeformiscandona hyalina, Herpetocypris chevreuxi, Heterocypris salina) and taxa reflecting profundal conditions (Candona neglecta, Cytherissa lacustris and Fabaeformiscandona caudata). Among these taxa, C. neglecta and D. stevensoni were the most abundant ostracod species providing more than 50 % of the fossil shells in most core samples. Where C. neglecta peaks D. stevensoni often shows minima abundances and vice versa. Stable isotope data derived from ostracod calcite display large variations throughout the core. d18O and d13C values vary over a range of 10 ‰ and 6.7 ‰ respectively. These large ranges may reflect that Lake Bosten responded like a semi-closed lake at least. Low lake levels inferred from species assemblages correspond to lowest d18O values thus indicating the influence of isotopically light river water at the core site and a low residence time and salinity. High d18O values correspond to higher abundances of Candona neglecta and low abundances of littoral taxa pointing towards deeper conditions, a higher distance of the core site from the river inflow, a higher residence time and corresponding salinity of the lake water. On the base of ostracod and stable

  19. Regional Consortia for E-Resources: A Case Study of Deals in the South China Region

    ERIC Educational Resources Information Center

    Chunrong, Luo; Jingfen, Wang; Zhinong, Zhou

    2010-01-01

    Purpose: The purpose of this paper is to analyse the current situation and the social and economic benefits from the consortia acquisitions of electronic resources by the China Academic Library and Information System (CALIS) South China Regional Centre and to recommend improvements for consortia acquisitions. Design/methodology/approach: Analyses…

  20. Predator-prey relations and competition for food between age-0 lake trout and slimy sculpins in the Apostle Island region of Lake Superior

    USGS Publications Warehouse

    Hudson, Patrick L.; Savino, Jacqueline F.; Bronte, Charles R.

    1995-01-01

    Slimy sculpins (Cottus cognatus) are an important component of the fish community on reefs and adjacent nursery areas of the Great Lakes and overlap spatially with age-0 lake trout (Salvelinus namaycush). Important interactions between these fishes are possible during the lake trout's first year of life, which could include predation on each other's eggs and larvae, and competition for food resources. We investigated the diets of age-0 lake trout and slimy sculpins on a lake trout spawning reef (Gull Island Shoal) and adjacent nursery area (near Michigan Island) in the Apostle Island region of western Lake Superior during June through September from 1988 through 1991. Organisms in stomachs of 511 lake trout and 562 sculpins were identified and counted. Of the 11 major food types found in age-0 lake trout stomachs from both areas, Mysis was the dominant food item (mean volume in stomachs = 68%) and occurred in about 3/4 of the fish analyzed. Copepods, cladocerans, chironomid pupae, fish, and Bythotrephes were also common in the diet (frequency of occurrence > 4%). Diets of lake trout were more diverse on the reef than on the nursery area where Mysis dominated the diet. Slimy sculpins were only found in lake trout greater than 50 mm. Mysis was an important food item of slimy sculpins over the reef but not over the nursery area, where Diporeia was by far the most important taxon. A variety ofben-thic invertebrates (Asellus, chironomids, benthic copepods, and snails) comprised the bulk of the sculpin diet over the reef. Sculpins also ate lake trout eggs in November. Based on cluster analysis, diets were most similar over the reef where both consumed Mysis, calanoid copepods and chironomid pupae. Diets diverged over the nursery areas where sculpins were strictly benthic feeders and lake trout maintained their planktonic diet. In Lake Superior, where lake trout recruitment through natural reproduction has become well established, the coexistence of the two

  1. Application of a comprehensive extraction technique for the determination of poly- and perfluoroalkyl substances (PFASs) in Great Lakes Region sediments.

    PubMed

    Guo, Rui; Megson, David; Myers, Anne L; Helm, Paul A; Marvin, Chris; Crozier, Patrick; Mabury, Scott; Bhavsar, Satyendra P; Tomy, Gregg; Simcik, Matt; McCarry, Brian; Reiner, Eric J

    2016-12-01

    A comprehensive method to extract perfluoroalkane sulfonic acids (PFSAs), perfluoroalkyl carboxylic acids (PFCAs), polyfluoroalkyl phosphoric acid diesters (diPAPs), perfluoroalkyl phosphinic acids (PFPiAs) and perfluoroalkyl phosphonic acids (PFPAs) from sediment and analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed and applied to sediment cores from three small isolated lakes (Plastic Lake, Lake 442, Lake Tettegouche) and Lake Ontario in the Great Lakes Region. Recoveries of the target compounds using the optimized acetonitrile/sodium hydroxide extraction ranged from 73% to 120%. The greatest concentrations of per- and polyfluorinated alkyl substances (PFASs) were recorded in sediment from Lake Ontario (ΣPFASs 13.1 ng/g), where perfluorooctane sulfonic acid (PFOS) contributed over 80% of the total. Concentrations in Lake Ontario were approximately 1-2 orders of magnitude greater than the more remote lakes subject to primarily atmospheric inputs. Whilst the PFAS contribution in Lake Ontario was dominated by PFOS, the more remote lakes contained sediment with higher proportions of PFCAs. Trace amounts of emerging PFASs (diPAPs and PFPiAs) were found in very recent surface Lake Ontario and remote lake sediments.

  2. A 1000-yr record of environmental change in NE China indicated by diatom assemblages from maar lake Erlongwan

    NASA Astrophysics Data System (ADS)

    Wang, Luo; Rioual, Patrick; Panizzo, Virginia N.; Lu, Houyuan; Gu, Zhaoyan; Chu, Guoqiang; Yang, Deguang; Han, Jingtai; Liu, Jiaqi; Mackay, Anson W.

    2012-07-01

    Past environmental changes based on diatom relative abundances have been inferred from the maar Lake Erlongwan in northeast China. The limnology of Lake Erlongwan is affected by the strongly seasonal regional climate. The composition of diatom assemblages, in turn, responds to changes in the seasonal duration of ice cover in winter, water-column turnover in spring and autumn, and thermal stratification in summer. Statistical analysis of the sedimentary diatom assemblages reveals three significant stratigraphic zones over the past 1000 yr. The highest abundance of the planktonic species Discostella species occurs between AD 1050 and 1400 and suggests an annual ice-free period of long duration and well-developed summer stratification of the water column. This planktonic diatom peak between ca. AD 1150 and 1200 suggests that this period was the warmest over the past 1000 yr. The interval between AD 1400 and 1800 is marked by a decline in planktonic diatoms and suggests shorter duration of the ice-free season, weaker water stratification and possibly generally cold conditions. After AD 1800 relative abundances of planktonic diatoms, including Puncticulata praetermissa and Asterionella formosa, increase again, which indicates lengthening of the duration of the annual ice-free period and a stronger overturn of the water column. All these data imply that the pattern of the seasons is different between the MWP and the 20th century.

  3. Computation of precise regional geoid in Great Lakes region using GOCE data and two different approaches

    NASA Astrophysics Data System (ADS)

    Janák, Juraj; Pitoňák, Martin; Minarechová, Zuzana; Huang, Jianliang

    2014-05-01

    The goal of our contribution is to compare the two regional models of the geoid in a relatively flat area around the Great Lakes - Canada and the USA. The first model is computed with the standard Stokes-Helmert (SH) approach while the second model is compiled as numerical Finite Element Solution (FE) to the geodetic boundary-value problem. The terrestrial data used as an input for both models are the same. The GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) input data are, however, different. The SH model uses the recent GOCE global geopotential model while the FE approach employs the grid of downward continued gravity anomalies derived from the GOCE gravitational gradients. The SH approach is well documented and described in many publications. The FE approach is recent and novelty approach which can be almost independent from the global geopotential model, except from the dependency inherited from the GOCE EGG_TRF2 data product. Moreover the FE approach is able to combine the terrestrial and satellite input data in a natural way. Both models are compared with GNSS-Levelling data to assess the accuracy of both models and efficiency of particular approaches.

  4. Is China's fifth-largest inland lake to dry-up? Incorporated hydrological and satellite-based methods for forecasting Hulun lake water levels

    NASA Astrophysics Data System (ADS)

    Cai, Zuansi; Jin, Taoyong; Li, Changyou; Ofterdinger, Ulrich; Zhang, Sheng; Ding, Aizhong; Li, Jiancheng

    2016-08-01

    Hulun Lake, China's fifth-largest inland lake, experienced severe declines in water level in the period of 2000-2010. This has prompted concerns whether the lake is drying up gradually. A multi-million US dollar engineering project to construct a water channel to transfer part of the river flow from a nearby river to maintain the water level was completed in August 2010. This study aimed to advance the understanding of the key processes controlling the lake water level variation over the last five decades, as well as investigate the impact of the river transfer engineering project on the water level. A water balance model was developed to investigate the lake water level variations over the last five decades, using hydrological and climatic data as well as satellite-based measurements and results from land surface modelling. The investigation reveals that the severe reduction of river discharge (-364 ± 64 mm/yr, ∼70% of the five-decade average) into the lake was the key factor behind the decline of the lake water level between 2000 and 2010. The decline of river discharge was due to the reduction of total runoff from the lake watershed. This was a result of the reduction of soil moisture due to the decrease of precipitation (-49 ± 45 mm/yr) over this period. The water budget calculation suggests that the groundwater component from the surrounding lake area as well as surface run off from the un-gauged area surrounding the lake contributed ∼ net 210 Mm3/yr (equivalent to ∼ 100 mm/yr) water inflows into the lake. The results also show that the water diversion project did prevent a further water level decline of over 0.5 m by the end of 2012. Overall, the monthly water balance model gave an excellent prediction of the lake water level fluctuation over the last five decades and can be a useful tool to manage lake water resources in the future.

  5. Increasing heavy metals in the background atmosphere of central North China since the 1980s: Evidence from a 200-year lake sediment record

    NASA Astrophysics Data System (ADS)

    Wan, Dejun; Song, Lei; Yang, Jinsong; Jin, Zhangdong; Zhan, Changlin; Mao, Xin; Liu, Dongwei; Shao, Yue

    2016-08-01

    Long-term trends of atmospheric compositions are significant for assessing the influence of human activities on the atmosphere and protecting the atmospheric environment. In this study, based on heavy metal concentrations and Pb isotope ratios in a well-dated sediment core from a remote alpine lake in central North China, anthropogenic fluxes of As, Cd, Sb, and Pb were reconstructed and heavy metal evolutions in the atmosphere were revealed in the last 200 years. The heavy metals in the atmosphere were generally natural origins before 1980 A.D. Since the 1980s they began to increase gradually, but they increased the most in the 1990s resulting from rapid developments of rough and high energy-consuming industries in North China. After entering the 21st century the industries still developed rapidly, but the atmospheric Pb ceased increase and the As and Sb even decreased in the 2000s due to (1) phasing out of leaded gasoline and (2) implementing stricter industrial emission standards in 2000 A.D. in China. However, in the 2000s the atmospheric heavy metals still kept at a relatively high level and even likely began to increase again in the 2010s. Considering the lake relatively remote and seldom affected by local human activities, the results likely reflect heavy metal evolutions in the regional background atmosphere of central North China at the annual/decadal timescale in the last 200 years.

  6. Glial cell biology in the Great Lakes region.

    PubMed

    Feinstein, Douglas L; Skoff, Robert P

    2016-03-31

    We report on the tenth bi-annual Great Lakes Glial meeting, held in Traverse City, Michigan, USA, September 27-29 2015. The GLG meeting is a small conference that focuses on current research in glial cell biology. The array of functions that glial cells (astrocytes, microglia, oligodendrocytes, Schwann cells) play in health and disease is constantly increasing. Despite this diversity, GLG meetings bring together scientists with common interests, leading to a better understanding of these cells. This year's meeting included two keynote speakers who presented talks on the regulation of CNS myelination and the consequences of stress on Schwann cell biology. Twenty-two other talks were presented along with two poster sessions. Sessions covered recent findings in the areas of microglial and astrocyte activation; age-dependent changes to glial cells, Schwann cell development and pathology, and the role of stem cells in glioma and neural regeneration.

  7. Modified Convair-240 aircraft at Naval Weapons Center, China Lake, California

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Convair-240 aircraft modified to fill role of a Space Shuttle is parked outside aircraft hangar at Naval Weapons Center, China Lake, California. Space shuttle side hatch mockup is incorporated in fuselage (visible toward the aft section of the aircraft). Convair-240 aircraft is part of November crew escape system (CES) testing of a candidate concept developed to provide crew egress capability during Space Shuttle controlled gliding flight. Tractor rocket testing using the Convair-240 will begin 11-20-87. Life-like dummies will be pulled by the rockets from the modified aircraft's side hatch mockup.

  8. The community structure and seasonal dynamics of plankton in Bange Lake, northern Tibet, China

    NASA Astrophysics Data System (ADS)

    Zhao, Wen; Zhao, Yuanyi; Wang, Qiaohan; Zheng, Mianping; Wei, Jie; Wang, Shan

    2016-11-01

    The seasonal variations in biomass, abundance, and species composition of plankton in relation to hydrography were studied in the saline Bange Lake, northern Tibet, China. Sampling was carried out between one to three times per month from May 2001 to July 2002. Salinity ranged from 14 to 146. The air and water temperature exhibited a clear seasonal pattern, and mean annual temperatures were approximately 4.8°C and 7.3°C, respectively. The lowest water temperature occurred in winter from December to March at -2°C and the highest in June and July at 17.7°C. Forty-one phytoplankton taxa, 21 zooplankton, and 5 benthic or facultative zooplankton were identified. The predominant phytoplankton species were Gloeothece linearis, Oscillatoria tenuis, Gloeocapsa punctata, Ctenocladus circinnatus, Dunaliella salina, and Spirulina major. The predominant zooplankton species included Holophrya actra, Brachionus plicatilis, Daphniopsis tibetana, Cletocamptus dertersi, and Arctodiaptomus salinus. The mean annual total phytoplankton density and biomass for the entire lake were 4.52×107 cells/L and 1.60 mg/L, respectively. The annual mean zooplankton abundance was 52, 162, 322, and 57, 144 ind./L, in the three sublakes. The annual mean total zooplankton biomass in Lakes 1-3 was 1.23, 9.98, and 2.13 mg/L, respectively. The annual mean tychoplankton abundances in Bg1, 2, and 3 were 47, 67, and 654 ind./L. The annual mean tychoplankton biomass was 2.36, 0.16, and 2.03 mg/L, respectively. The zooplankton biomass (including tychoplankton) in the lake was 9.11 mg/L. The total number of plankton species in the salt lake was significantly negatively correlated with salinity.

  9. Response of freshwater algae to water quality in Qinshan Lake within Taihu Watershed, China

    NASA Astrophysics Data System (ADS)

    Zhang, Jianying; Ni, Wanmin; Luo, Yang; Jan Stevenson, R.; Qi, Jiaguo

    Although frequent algal blooms in Taihu Lake in China have become major environmental problems and have drawn national and international attention, little is understood about the relationship between algal blooms and water quality. The goal of this study was to assess the growth and species responses of freshwater algae to variation in water quality in Qinshan Lake, located in headwaters of the Taihu watershed. Water samples were collected monthly from ten study sites in the Qinshan Lake and were analyzed for species distribution of freshwater algae and physiochemical parameters such as total nitrogen (TN), NH4+-N, NO3--N, total phosphorus (TP), chemical oxygen demand (COD Mn) and Chl-a. The results showed that average TN was 4.47 mg/L, with 92.2% of values greater than the TN standard set by the Chinese Environmental Protection Agency; average TP was 0.051 mg/L, with 37.9% of values above the TP national standard; and average trophic level index (TLI) was 53, the lower end of eutrophic condition. Average Chl-a concentration was 12.83 mg/m 3. Green algae and diatom far outweighed other freshwater algae and were dominant most time of the year, with the highest relative abundances of 96% and 99%, respectively. Blue-green algae, composed mainly toxic strains like Microcystis sp ., Nostoc sp. and Oscillatoria sp., became most dominant in the summer with the maximum relative abundance of 69%. The blue-green algae sank to the lake bottom to overwinter, and then dinoflagellates became the dominant species in the winter, with highest relative abundance of 89%. Analysis indicated that nutrients, especially control of ammonia and co-varying nutrients were the major restrictive factor of population growth of blue-green algae, suggesting that control in nutrient enrichments is the major preventive measure of algal blooms in Qinshan Lake.

  10. Regional spatial and temporal interpolation of atmospheric PCBs: Interpretation of Lake Michigan mass balance data

    SciTech Connect

    Green, M.L.; Depinto, J.V.; Sweet, C.; Hornbuckle, K.C.

    2000-05-01

    During the Lake Michigan Mass Balance (LMMB) Project, over 600 atmospheric samples were collected at eight shoreline sites and during seven cruises. These samples were analyzed for persistent organic pollutants, including PCB congeners, atrazine, and trans-nonachlor. The authors have developed a method for interpreting the gas-phase data that includes fractionating the observed PCB concentration into land- and water-based sources. This approach accounts for differences in gas-phase atmospheric PCB concentration over water and over land. Using this fractionation approach, they have interpolated the measured data over time and space to predict PCB air concentrations over the lake during the LMMB field period. The results predict gas-phase {Sigma}PCB (sum of {approximately}98 congener groups) concentrations for each of 2,319 grid cells over the lake, on a monthly basis. The authors estimate that lake-wide monthly average {sigma}PCB gas-phase concentrations range from 0.136 to 1.158 ng/m{sup 3}, with an annual average PCB concentration of 0.457 ng/m{sup 3}. As expected, the highest concentrations of PCBs over the lake when the winds are from the southwest (out of the Chicago-Gary region) and when land surface temperatures are elevated. The predicted influence of Chicago is described on a monthly basis as a zone of elevated PCB concentrations for approximately 40 km into Lake Michigan.

  11. Late quaternary temporal and event classifications, Great Lakes region, North America

    USGS Publications Warehouse

    Johnson, W.H.; Hansel, A.K.; Bettis, E. Arthur; Karrow, P.F.; Larson, G.J.; Lowell, T.V.; Schneider, Allan F.

    1997-01-01

    Several temporal and event classifications are used for the Quaternary glacial and interglacial record in the Great Lakes region of North America. Although based on contrasting principles, the classifications, as practiced, are similar to one another in most respects and they differ little from the classification proposed by Chamberlin a century ago. All are based on stratigraphic units having time-transgressive boundaries; thus the associated time spans and events are diachronous. Where application of geochronologic classification based on isochronous boundaries is not practical or useful, we advocate the use of diachronic principles to establish local and regional temporal and event classifications. Diachronic and event classifications based on such principles are proposed herein for the Great Lakes region. Well-established names, including Wisconsin, Sangamon, and Illinois, are used at the episode (or glaciation/interglaciation) rank without significant redefinition. The Hudson Episode (Interglaciation) is introduced for postglacial time, the current interglacial interval. The Wisconsin Episode is divided into the Ontario, Elgin, and Michigan Subepisodes in the eastern and northern parts of the Great Lakes region and into the Athens and Michigan Subepisodes in the southern and western parts of the Great Lakes region. ?? 1997 University of Washington.

  12. Digital Data for Volcano Hazards in the Crater Lake Region, Oregon

    USGS Publications Warehouse

    Schilling, S.P.; Doelger, S.; Bacon, C.R.; Mastin, L.G.; Scott, K.E.; Nathenson, M.

    2008-01-01

    Crater Lake lies in a basin, or caldera, formed by collapse of the Cascade volcano known as Mount Mazama during a violent, climactic eruption about 7,700 years ago. This event dramatically changed the character of the volcano so that many potential types of future events have no precedent there. This potentially active volcanic center is contained within Crater Lake National Park, visited by 500,000 people per year, and is adjacent to the main transportation corridor east of the Cascade Range. Because a lake is now present within the most likely site of future volcanic activity, many of the hazards at Crater Lake are different from those at most other Cascade volcanoes. Also significant are many faults near Crater Lake that clearly have been active in the recent past. These faults, and historic seismicity, indicate that damaging earthquakes can occur there in the future. The USGS Open-File Report 97-487 (Bacon and others, 1997) describes the various types of volcano and earthquake hazards in the Crater Lake area, estimates of the likelihood of future events, recommendations for mitigation, and a map of hazard zones. The geographic information system (GIS) volcano hazard data layers used to produce the Crater Lake earthquake and volcano hazard map in USGS Open-File Report 97-487 are included in this data set. USGS scientists created one GIS data layer, c_faults, that delineates these faults and one layer, cballs, that depicts the downthrown side of the faults. Additional GIS layers chazline, chaz, and chazpoly were created to show 1)the extent of pumiceous pyroclastic-flow deposits of the caldera forming Mount Mazama eruption, 2)silicic and mafic vents in the Crater Lake region, and 3)the proximal hazard zone around the caldera rim, respectively.

  13. Potential Effects of Climate Changes on Aquatic Systems: Laurentian Great Lakes and Precambrian Shield Region

    NASA Astrophysics Data System (ADS)

    Magnuson, J. J.; Webster, K. E.; Assel, R. A.; Bowser, C. J.; Dillon, P. J.; Eaton, J. G.; Evans, H. E.; Fee, E. J.; Hall, R. I.; Mortsch, L. R.; Schindler, D. W.; Quinn, F. H.

    1997-06-01

    The region studied includes the Laurentian Great Lakes and a diversity of smaller glacial lakes, streams and wetlands south of permanent permafrost and towards the southern extent of Wisconsin glaciation. We emphasize lakes and quantitative implications. The region is warmer and wetter than it has been over most of the last 12000 years. Since 1911 observed air temperatures have increased by about 0·11°C per decade in spring and 0·06°C in winter; annual precipitation has increased by about 2·1% per decade. Ice thaw phenologies since the 1850s indicate a late winter warming of about 2·5°C. In future scenarios for a doubled CO2 climate, air temperature increases in summer and winter and precipitation decreases (summer) in western Ontario but increases (winter) in western Ontario, northern Minnesota, Wisconsin and Michigan. Such changes in climate have altered and would further alter hydrological and other physical features of lakes. Warmer climates, i.e. 2 × CO2 climates, would lower net basin water supplies, stream flows and water levels owing to increased evaporation in excess of precipitation. Water levels have been responsive to drought and future scenarios for the Great Lakes simulate levels 0·2 to 2·5 m lower. Human adaptation to such changes is expensive. Warmer climates would decrease the spatial extent of ice cover on the Great Lakes; small lakes, especially to the south, would no longer freeze over every year. Temperature simulations for stratified lakes are 1-7°C warmer for surface waters, and 6°C cooler to 8°C warmer for deep waters. Thermocline depth would change (4 m shallower to 3·5 m deeper) with warmer climates alone; deepening owing to increases in light penetration would occur with reduced input of dissolved organic carbon (DOC) from dryer catchments. Dissolved oxygen would decrease below the thermocline. These physical changes would in turn affect the phytoplankton, zooplankton, benthos and fishes. Annual phytoplankton production may

  14. Risk assessment for sustainable food security in China according to integrated food security--taking Dongting Lake area for example.

    PubMed

    Qi, Xiaoxing; Liu, Liming; Liu, Yabin; Yao, Lan

    2013-06-01

    Integrated food security covers three aspects: food quantity security, food quality security, and sustainable food security. Because sustainable food security requires that food security must be compatible with sustainable development, the risk assessment of sustainable food security is becoming one of the most important issues. This paper mainly focuses on the characteristics of sustainable food security problems in the major grain-producing areas in China. We establish an index system based on land resources and eco-environmental conditions and apply a dynamic assessment method based on status assessments and trend analysis models to overcome the shortcomings of the static evaluation method. Using fuzzy mathematics, the risks are categorized into four grades: negligible risk, low risk, medium risk, and high risk. A case study was conducted in one of China's major grain-producing areas: Dongting Lake area. The results predict that the status of the sustainable food security in the Dongting Lake area is unsatisfactory for the foreseeable future. The number of districts at the medium-risk range will increase from six to ten by 2015 due to increasing population pressure, a decrease in the cultivated area, and a decrease in the effective irrigation area. Therefore, appropriate policies and measures should be put forward to improve it. The results could also provide direct support for an early warning system-which could be used to monitor food security trends or nutritional status so to inform policy makers of impending food shortages-to prevent sustainable food security risk based on some classical systematic methods. This is the first research of sustainable food security in terms of risk assessment, from the perspective of resources and the environment, at the regional scale.

  15. Electromagnetic Surveying in the Mangrove Lakes Region of Everglades National Park

    NASA Astrophysics Data System (ADS)

    Whitman, D.; Price, R.; Frankovich, T.; Fourqurean, J.

    2015-12-01

    The Mangrove Lakes are an interconnected set of shallow (~ 1m), brackish lake and creek systems on the southern margin of the Everglades adjacent to Florida Bay. Current efforts associated with the Comprehensive Everglades Restoration Plan (CERP) aim to increase freshwater flow into this region. This study describes preliminary results of geophysical surveys in the lakes conducted to assess changes in the groundwater chemistry as part of a larger hydrologic and geochemical study in the Everglades Lakes region. Marine geophysical profiles were conducted in Alligator Creek (West Lake) and McCormick Creek systems in May, 2014. Data included marine electromagnetic (EM) profiles and soundings, water depth measurements, surface water conductivity and salinity measurements. A GSSI Profiler EMP-400 multi-frequency EM conductivity meter continuously recorded in-phase and quadrature field components at 1, 8, and 15 KHz. The system was deployed in a flat bottomed plastic kayak towed behind a motorized skiff. Lake water depths were continuously measured with a sounder/chart plotter which was calibrated with periodic sounding rod measurements. At periodic intervals during the survey, the profiling was stopped and surface water conductivity, temperature and salinity are recorded with a portable YSI probe on the tow boat. Over 40,000 discrete 3-frequency EM measurements were collected. The data were inverted to 2-layer models representing the water layer thickness and conductivity and the lake bottom conductivity. At spot locations, models were constrained with water depth soundings and surface water conductivity measurements. At other locations along the profiles, the water depth and conductivity were allowed to be free, but the free models were generally consistent with the constrained models. Multilayer sub-bottom models were also explored but were found to be poorly constrained. In West Lake, sub-bottom conductivities decreased from 400 mS/m in the west to 200 mS/m in the

  16. The Professional Reading Habits of Senior Housing Officers at ACUHO-I Member Institutions in the Great Lakes Region

    ERIC Educational Resources Information Center

    O'Dell, Kyle

    2009-01-01

    This study examined the professional reading habits of Senior Housing Officers (SHOs) at ACUHO-I member institutions in the Great Lakes region, which encompasses the states of Ohio, Michigan, Illinois, and Indiana. The findings were based on data from the survey responses of SHOs at 71 colleges and universities across the Great Lakes region of the…

  17. A numerical study on the influence of fractured regions on lake/groundwater interaction; the Lake Kinneret (Sea of Galilee) case

    NASA Astrophysics Data System (ADS)

    Abbo, Hila; Shavit, Uri; Markel, Doron; Rimmer, Alon

    2003-12-01

    Increased lake salinity is a growing problem in arid and semi-arid regions. Operational management, which is based on a reliable hydrological understanding, has the potential to reduce the lake salinity. This is the case of the salinity in Lake Kinneret (Sea of Galilee), where saline water flows into the lake through on-shore and off-shore springs. Here, we present a time-dependent flow and transport numerical model that successfully reproduces the monitored groundwater level, discharge, and salinity of the lake springs. The model utilizes a continuum approach and describes the flow through a confined saline carbonate aquifer, which interacts with the discharge lake through fractures and faults. In particular, the model investigates the hydrology around two groups of springs, Fuliya and Tabgha, along the western shore of the lake. Based on seasonal characteristics of the springs and measured boundary conditions, the two springs groups were defined as Lake Dominated Springs (LDS, Fuliya) and Aquifer Dominated Springs (ADS, Tabgha). The models of the two groups differ from each other in the distribution of fractured regions that link between the lake and the underlying aquifers. The numerical solution shows how the fractured regions affect groundwater head, spring discharge, and spring salinity. The different behavior of the LDS and ADS was reproduced with an excellent agreement between measured and calculated patterns. Differences in salinity within a group of springs are shown to be dependent on the depth of the fractured region. It was revealed that in addition to the appropriate distribution of fractured regions some adjustment in the up-stream boundary conditions is necessary to fully reproduce the system hydrology. The model has improved our understanding and provides a prediction tool for future management strategies.

  18. Quantification and index of non-point source pollution in Taihu Lake region with GIS.

    PubMed

    Guo, H Y; Wang, X R; Zhu, J G

    2004-01-01

    The contribution of phosphorus and nitrogen from non-point source pollution (NPS) in the Taihu Lake region was investigated through case study and surveying in the town of Xueyan, From experimental results coupled with survey and statistics in the studied area, the distribution of nitrogen and phosphorus input to the water body is achieved from four main sources: agricultural land, village, the town center and the poultry factory. The results showed that about 38% of total phosphorus (TP) and 48% of total nitrogen (TN) discharged is from agricultural land, 33% of TP and 40% TN from village residents, 25% of TP and 10% of TN from the town center and 4% of TP and 2% of TN from the poultry factory. The Agricultural Non-point Pollution Potential Index (APPI) system for identifying and ranking critical areas of NPS was established with a Geographic Information Systems (GIS)-based technology. Quantification of the key factors in non-point sources pollution was carried out utilizing the following: Sediment Production Index (SPI), Runoff Index (RI), People and Animal Loading Index (PALI) and Chemical Use Index (CUI). These are the core parts of the model, and the weighting factor of each index was evaluated according the results of quantification. The model was successfully applied for evaluating APPI in Xueyan. Results from the model showed that the critical area identified for NPS control in Xueyan. The model has several advantages including: requiring fewer parameters, easy acquirement of these parameters, friendly interface, and convenience of operation. In addition it is especially useful for identifying critical areas of NPS when the basic data are not fully accessible, which is the present situation in China.

  19. National investigation of semi-volatile organic compounds (PAHs, OCPs, and PCBs) in lake sediments of China: Occurrence, spatial variation and risk assessment.

    PubMed

    Li, Chaocan; Huo, Shouliang; Yu, Zhiqiang; Xi, Beidou; Yeager, Kevin M; He, Zhuoshi; Ma, Chunzi; Zhang, Jingtian; Wu, Fengchang

    2017-02-01

    In this study, a large scale investigation of semi-volatile organic compounds (SVOCs) in sediments from 52 lakes, located in five geographic regions across China, was conducted to assess sediment quality in terms of organic contaminants. Concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs) in sediment were found to range between 17.00-6,633, 0.12-45.24, and 0.03-13.99ngg(-1), respectively. Lake sediments from different regions exhibited variation in contamination levels, and in the compositions of isomers. The descending order of contamination levels for the three SVOCs groups (i.e., ∑PAHs, ∑OCPs, ∑PCBs) were as follows: the eastern plain region (EPR)>the Yunnan-Guizhou plateau (YGP)>the northeast China region (NCR)>the Qinghai-Tibet plateau (QTP)>the Mongolia-Xinjiang plateau (MXP). High molecular weight PAHs, OCPs and PCBs were found at high concentrations in parts of the EPR and YGP, while lighter isomers were likely to be atmospherically transported, resulting in their nationwide distribution. The sources and type variation (local input or atmospheric deposition) are the primary controls of spatial variation. Additionally, human related socio-economic factors, and geographic conditions also played important roles in influencing the spatial differentiation. According to simple sediment quality guidelines (SQG), the risks posed by PCBs in sediments were not as serious as those posed by PAHs and DDT.

  20. Spatial and Temporal Trends of Snowfall in Central New York - A Lake Effect Dominated Region

    NASA Astrophysics Data System (ADS)

    Hartnett, Justin Joseph

    Central New York is located in one of the snowiest regions in the United States, with the city of Syracuse, New York the snowiest metropolis in the nation. Snowfall in the region generally begins in mid-November and lasts until late-March. Snow accumulation occurs from a multitude of conditions: frontal systems, mid-latitude cyclones, Nor'easters, and most notably lake-effect storms. Lake effect snowfall (LES) is a difficult parameter to forecast due to the isolated and highly variable nature of the storm. Consequently, studies have attempted to determine changes in snowfall for lake-effect dominated regions. Annual snowfall patterns are of particular concern as seasonal snowfall totals are vital for water resources, winter businesses, agriculture, government and state agencies, and much more. Through the use of snowfall, temperature, precipitation, and location data from the National Weather Service's Cooperative Observer Program (COOP), spatial and temporal changes in snowfall for Central New York were determined. In order to determine climatic changes in snowfall, statistical analyses were performed (i.e. least squares estimation, correlations, principal component analyses, etc.) and spatial maps analyzed. Once snowfall trends were determined, factors influencing the trends were examined. Long-term snowfall trends for CNY were positive for original stations (˜0.46 +/- 0.20 in. yr -1) and homogenously filtered stations (0.23 +/- 0.20 in. yr -1). However, snowfall trends for shorter time-increments within the long-term period were not consistent, as positive, negative, and neutral trends were calculated. Regional differences in snowfall trends were observed for CNY as typical lake-effect areas (northern counties, the Tug Hill Plateau and the Southern Hills) experienced larger snowfall trends than areas less dominated by LES. Typical lake-effect months (December - February) experienced the greatest snowfall trend in CNY compared to other winter months. The

  1. A REGIONAL ANALYSIS OF LAKE ACIDIFICATION TRENDS FOR THE NORTHEASTEN U.S., 1982-1994

    EPA Science Inventory

    Acidic deposition is a regional phenomenon, but its effects have traditionally been studied using site-specific, intensive monitoring. We present trends information for 36 lakes of high-to-moderate acid sensitivity (defined as acid neutralizing capacity [ANC] < 100 eq L-1),and 1...

  2. 40 CFR 81.128 - Genesee-Finger Lakes Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES Designation of... Genesee-Finger Lakes Intrastate Air Quality Control Region (New York) consists of the territorial area encompassed by the boundaries of the following jurisdictions or described area (including the territorial...

  3. 40 CFR 81.128 - Genesee-Finger Lakes Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES Designation of... Genesee-Finger Lakes Intrastate Air Quality Control Region (New York) consists of the territorial area encompassed by the boundaries of the following jurisdictions or described area (including the territorial...

  4. The ralationship between the Tamarix spp. growth and lake level change in the Bosten Lake,northwest China

    NASA Astrophysics Data System (ADS)

    Ye, Mao; Hou, JiaWen

    2015-04-01

    Dendrochronology methods are used to analyze the characteristics of Tamarix spp. growth in Bosten Lake. Based on the long-term annual and monthly data of lake level, this paper models the relationship between ring width of Tamarix spp. and lake level change. The sensitivity index is applied to determine the rational change range of lake level for protecting the Tamarix spp. growth. The results show that :( 1) the annual change of lake level in Bosten Lake has tree evident stages from 1955 to 2012. The monthly change of lake level has two peak values and the seasonal change is not significant; (2) the average value of radical width of Tamarix spp. is 3.39mm. With the increment of Tamarix spp. annual growth , the average radical width has a decreasing trend, which is similar to the annual change trend of lake level in the same years ;( 3) the response of the radical width of Tamarix spp. to annual change of lake level is sensitive significantly. When the lake level is 1045.66m, the Sk value of radical width of Tamarix spp. appears minimum .when the lake level is up to1046.27m, the Sk value is maximum. Thus the sensitivity level of radical width of Tamarix spp. is 1045.66- 1046.27m which could be regarded as the rational lake level change range for protecting the Tamarix spp. growth.

  5. Temporal and spatial changes in nutrients and chlorophyll-a in a shallow lake, Lake Chaohu, China: an 11-year investigation.

    PubMed

    Yang, Libiao; Lei, Kun; Meng, Wei; Fu, Guo; Yan, Weijin

    2013-06-01

    Temporal and spatial changes of total nitrogen (TN), total phosphorus (TP) and chlorophyll-a (Chl-a) in a shallow lake, Lake Chaohu, China, were investigated using monthly monitoring data from 2001 through 2011. The results showed that the annual mean concentration ranges of TN, TP, and Chl-a were 0.08-14.60 mg/L, 0.02-1.08 mg/L, and 0.10-465.90 microg/L, respectively. Our data showed that Lake Chaohu was highly eutrophic and that water quality showed no substantial improvement during 2001 through 2011. The mean concentrations of TP, TN and Chl-a in the western lake were significantly higher than in the eastern lake, which indicates a spatial distribution of the three water parameters. The annual mean ratio of TN:TP by weight ranged from 10 to 20, indicating that phosphorus was the limiting nutrient in this lake. A similar seasonality variation for TP and Chl-a was observed. Riverine TP and NH4+ loading from eight major tributaries were in the range of 1.56 x 10(4)-5.47 x 10(4) and 0.19 x 10(4)-0.51 x 10(4) tons/yr over 2002-2011, respectively, and exceeded the water environmental capability of the two nutrients in the lake by a factor of 3-6. Thus reduction of nutrient loading in the sub-watershed and tributaries would be essential for the restoration of Lake Chaohu.

  6. Changes in the area of inland lakes in arid regions of central Asia during the past 30 years.

    PubMed

    Bai, Jie; Chen, Xi; Li, Junli; Yang, Liao; Fang, Hui

    2011-07-01

    Inland lakes are major surface water resource in arid regions of Central Asia. The area changes in these lakes have been proved to be the results of regional climate changes and recent human activities. This study aimed at investigating the area variations of the nine major lakes in Central Asia over the last 30 years. Firstly, multi-temporal Landsat imagery in 1975, 1990, 1999, and 2007 were used to delineate lake extents automatically based on Normalized Difference Water Index (NDWI) threshold segmentation, then lake area variations were detailed in three decades and the mechanism of these changes was analyzed with meteorological data and hydrological data. The results indicated that the total surface areas of these nine lakes had decreased from 91,402.06 km(2) to 46,049.23 km(2) during 1975-2007, accounting for 49.62% of their original area of 1975. Tail-end lakes in flat areas had shrunk dramatically as they were induced by both climate changes and human impacts, while alpine lakes remained relatively stable due to the small precipitation variations. With different water usage of river outlets, the variations of open lakes were more flexible than those of other two types. According to comprehensive analyses, different types of inland lakes presented different trends of area changes under the background of global warming effects in Central Asia, which showed that the increased human activities had broken the balance of water cycles in this region.

  7. Climate and environmental changes over the past 150 years inferred from the sediments of Chaiwopu Lake, central Tianshan Mountains, northwest China

    NASA Astrophysics Data System (ADS)

    Ma, Long; Wu, Jinglu; Abuduwaili, Jilili

    2013-04-01

    We used a 55-cm sediment core from shallow Chaiwopu Lake in the central Tianshan Mountains of Xinjiang, northwest China, to investigate climate and environmental changes in this arid region over the past ~150 years. The core was dated using 137Cs. We compared temporal changes in several sediment variables with recent meteorological and tree-ring records. Organic matter had a positive correlation with the Palmer Drought Severity Index in the central Tianshan Mountains, and the δ13C of organic matter had a positive correlation with regional temperature. We applied constrained incremental sum-of-squares cluster analysis to element concentrations in the core and identified three distinct zones: (1) 55-46 cm, ~1860-1910, (2) 46-26 cm, ~1910-1952, and (3) 26-0 cm, 1952-present. Between 1880 and 1910 AD, following the Little Ice Age (LIA), the sediment environment was relatively stable, climate was cold and dry, and the lake water displayed high salinity, in contrast to conditions during the LIA. During the LIA, westerlies carried more water vapor into Central Asia when the North Atlantic Oscillation was in a negative phase, and encountered the enhanced Siberia High, which probably led to increased precipitation. In the period 1910-1950 AD, the lake was shallow and the regional climate was unstable, with high temperatures and humidity. In the last ~15-20 years, human activities caused an increase in sediment magnetic susceptibility, and heavy metal and total phosphorus concentrations in the sediment were substantially enriched. Mean annual temperature displays a warming trend over the past 50 years, and the lowest temperature was observed in the 1950s. There has been an increase in annual total precipitation since the 1990s. The combined influences of climate and human activity on the lake environment during this period were faithfully recorded in sediments of Chaiwopu Lake. This study provides a scientific basis for environmental management and protection.

  8. Phytoplankton variation and its relationship with the environmental factors in Nansi Lake, China.

    PubMed

    Tian, Chang; Pei, Haiyan; Hu, Wenrong; Xie, Jun

    2013-01-01

    Nansi Lake is an important storage lake in the east route of the South-to-North Water Diversion Project in China, about which there has been serious concern regarding the water quality. In this study, the phytoplankton taxonomic composition, abundance, temporal variations, spatial distribution, and diversity were studied based on a monthly sampling campaign from five sampling stations between January 2010 and December 2010. A total of 159 species (8 phyla, 79 genera), including 74 species of Chlorophyta, 36 species of Bacillariophyta, 19 species of Cyanophyta (including 2 water bloom causative species), 21 species of Euglenophyta, 3 species of Cryptophyta, 5 species of Xanthophyta, 2 species of Pyrrophyta, and 2 species of Chrysophyta, were identified. Average phytoplankton diversity index and evenness values were 4.33 and 0.81, respectively, revealing high biodiversity of phytoplankton community. The phytoplankton abundance averaged at 9.51 × 10(6) cells L(-1) and was much higher than previous investigations carried out in 1983-1984. The dominant species were Bacillariophyta, Chlorophyta in winter and spring, and Chlorophyta and Cyanophyta in summer and atutumn. There were 14 predominant species including Chlorella vulgaris, Cyclotella stelligera, Pseudanabaena limnetica, and Chroomonas acuta. Phytoplankton community structure and environmental variable changed substantially over the survey period. Redundancy Analysis was used to analyze the relationship between them. Temperature was considered to be the key factor driving the change in phytoplankton community composition in Nansi Lake during the 2010 study period.

  9. Seasonal dynamics of phytoplankton and its relationship with the environmental factors in Dongping Lake, China.

    PubMed

    Tian, Chang; Lu, Xuetang; Pei, Haiyan; Hu, Wenrong; Xie, Jun

    2013-03-01

    Dongping Lake is the final adjusting and storing lake in the east route of the South-to-North Water Diversion Project in China, and there has been serious concern regarding the water quality. Understanding the process of phytoplankton variation can be particularly useful in water quality improvement and management decisions. In this study, the phytoplankton taxonomic composition, abundance, temporal variations, spatial distribution, and diversity were studied based on a monthly sampling campaign from three sampling stations between May 2010 and May 2011. A total of 132 species (8 phyla, 72 genera), including 64 species of Chlorophyta, 26 species of Bacillariophyta, 21 species of Cyanophyta, 12 species of Euglenophyta, 3 species of Cryptophyta, 2 species of Xanthophyta, 1 species of Pyrrophyta, and 3 species of Chrysophyta were identified. Average phytoplankton diversity index and evenness values were 3.83 and 0.77, respectively, revealing a high biodiversity of phytoplankton community. The phytoplankton abundance averaged 5.11 × 10(6) cells/L, with Bacillariophyta dominant in winter and spring, but Cyanophyta in summer and autumn. There were 14 predominant species including Pseudanabaena limnetica, Chlamydomonas simplex, Cyclotella stelligera, and Chroomonas acuta. Phytoplankton community structure and water quality variables changed substantially over the survey period; redundancy analysis, Pearson correlations, and regression analysis as an integrated approach were applied to analyze the relationships among them. Total phosphorus and ammonium played governing roles in the phytoplankton dynamics of Dongping Lake during all periods investigated.

  10. Evaluation of hyperspectral indices for chlorophyll-a concentration estimation in Tangxun Lake (Wuhan, China).

    PubMed

    Huang, Yaohuan; Jiang, Dong; Zhuang, Dafang; Fu, Jingying

    2010-06-01

    Chlorophyll-a (Chl-a) concentration is a major indicator of water quality which is harmful to human health. A growing number of studies have focused on the derivation of Chl-a concentration information from hyperspectral sensor data and the identification of best indices for Chl-a monitoring. The objective of this study is to assess the potential of hyperspectral indices to detect Chl-a concentrations in Tangxun Lake, which is the second largest lake in Wuhan, Central China. Hyperspectral reflectance and Chl-a concentration were measured at ten sample sites in Tangxun Lake. Three types of hyperspectral methods, including single-band reflectance, first derivative of reflectance, and reflectance ratio, were extracted from the spectral profiles of all bands of the hyperspectral sensor. The most appropriate bands for algorithms mentioned above were selected based on the correlation analysis. Evaluation results indicated that two methods, the first derivative of reflectance and reflectance ratio, were highly correlated (R(2) > 0.8) with the measured Chl-a concentrations. Thus, the spatial and temporal variations of Chl-a concentration could be conveniently monitored with these hyperspectral methods.

  11. Transformation of external sulphate and its effect on phosphorus mobilization in Lake Moshui, Wuhan, China.

    PubMed

    Yu, Fenfang; Zou, Jiajia; Hua, Yumei; Zhang, Shaohui; Liu, Guanglong; Zhu, Duanwei

    2015-11-01

    Average concentrations of sulphate in lakes continue to increase sharply. The response of phosphorus to sulphate input is of great importance due to the relationship between eutrophication and ecological health. A four-week experiment was conducted under simulated conditions using samples from a heavily polluted lake, Lake Moshui, in Wuhan, China, to examine the influence of external sulphate on phosphorus release and the transformation of sulphate. The results showed that the diffusion of sulphate into the sediments promoted the proliferation of sulphate-reducing bacteria (SRB) and the reduction of sulphate. Acetic acid was consumed due to sulphate reduction. The soluble reactive phosphorus (SRP) and soluble Fe measured with diffusive equilibration in thin-films (DET) probes increased significantly after the input of sulphate. The content of SRP was consistent with the variation in both the SRB number and the S(0) content in the sediments. The maximum SRP concentration of 100.43 mg L(-1) was recorded 3 cm below the sediment-water interface on the 29th d, which was more than twice the value of the control. There was a positive correlation between concentrations of Fe and SRP in the overlying water and the pore water of the sediments.

  12. Late Holocene Indian summer monsoon variations recorded at Lake Erhai, Southwestern China

    NASA Astrophysics Data System (ADS)

    Xu, Hai; Zhou, Xinying; Lan, Jianghu; Liu, Bin; Sheng, Enguo; Yu, Keke; Cheng, Peng; Wu, Feng; Hong, Bin; Yeager, Kevin M.; Xu, Sheng

    2015-03-01

    In this study we report changes in Indian summer monsoon (ISM) intensity during the past ~ 3500 yr inferred from proxy indices at Lake Erhai, southwestern China. Both the pollen concentrations and other proxy indices, including sediment grain size, total organic carbon contents (TOC), and elemental contents (e.g., Fe, Al), clearly indicate a long term decreasing trend in ISM intensity over the late Holocene. During the period from approximately AD 750 to AD 1200, pollen concentrations of conifer and broadleaf trees, and herbs reached the lowest levels over the past ~ 3500 yr; while the pollen percentages of both herbs and broadleaf trees increased, suggesting a significant medieval drought. The grain size, TOC, and elemental contents also support an arid climate during the medieval period. The Little Ice Age (LIA) at Lake Erhai was characterized as cold and wet. The medieval and LIA climatic patterns at Lake Erhai were similar to those over most of the ISM areas, but anti-phase with those over East Asian summer monsoon (EASM) areas. We suspect that sea surface temperature variations in the Indo-Pacific oceans and the related land-sea thermal contrasts may be responsible for such hydroclimatic differences between EASM and ISM areas.

  13. Cryptosporidium Contamination and Attributed Risks in Yunlong Lake in Xuzhou, China

    PubMed Central

    Kong, Yadong; Yuan, Tao; Niu, Jinghui; Li, Zhaoji; Yang, Baisong

    2017-01-01

    Swimming in surface water bodies (e.g., lakes, rivers) can expose the human body to substantial risk of infection by Cryptosporidium. These findings are from a one-year investigation on the occurrence and distribution of the protozoan parasite Cryptosporidium in Yunlong Lake, Xuzhou, China. Cryptosporidium oocysts were detected by immunofluorescence microscopy. From January to November of 2015, 180 samples (120 water samples and 60 sediment samples) were collected and analyzed. Among them, 42 (35%) water samples and 28 (47%) sediment samples tested positive for Cryptosporidium. The concentration of Cryptosporidium oocysts in the water samples was 0–8/10 L and 0–260/g in sediment samples. Results revealed that July was the highest risk period for both swimming and diving with an estimated probability of infection from swimming of greater than 18 per 10,000 swim sessions. It was concluded that swimming or diving in Yunlong Lake has a higher risk of Cryptosporidium infection than the acceptable risk level set by the United States Environmental Protection Agency. Thus, regular monitoring of water quality in recreation water bodies is strongly recommended. PMID:28386287

  14. Multi-Year Assessment of Toxic Genotypes and Microcystin Concentration in Northern Lake Taihu, China

    PubMed Central

    Hu, Lili; Shan, Kun; Lin, Lizhou; Shen, Wei; Huang, Licheng; Gan, Nanqin; Song, Lirong

    2016-01-01

    Lake Taihu is the third-largest freshwater lake in China and has been suffering from cyanobacterial blooms for over two decades. The northern part of the lake, Meiliang Bay, is known to be at high risk of dense and sustained Microcystis blooms and toxins. This study aimed to investigate and record the annual and seasonal dynamics of toxic genotype, Microcystis morphospecies succession and microcystin variation. It also aimed to find out the underlying driving factors influencing the dynamic changes. Microcystin (MC) and the Microcystis genotype were quantified using HPLC and quantitative real-time PCR, respectively. Our study, over three consecutive years, showed that the pattern of morphospecies succession was seasonally distinct and annually consistent. During the same period in 2012, 2013 and 2014, the average MC were, on dry weight basis, 733 μg·g−1, 844 μg·g−1, 870 μg·g−1, respectively. The proportion of toxic Microcystis accounted for 41%, 44% and 52%, respectively. Cell bound microcystin was found to correlate with the percentage of toxic Microcystis. Based on historical and current data, we conclude that annual bloom toxicity was relatively stable or possibly increased over the last decade. PMID:26784229

  15. Occurrence, bioaccumulation, and trophic magnification of pharmaceutically active compounds in Taihu Lake, China.

    PubMed

    Xie, Zhengxin; Lu, Guanghua; Liu, Jianchao; Yan, Zhenhua; Ma, Binni; Zhang, Zhenghua; Chen, Wei

    2015-11-01

    The occurrence, bioaccumulation, and trophic magnification of pharmaceutically active compounds, (PhACs) including antibiotics (roxithromycin and erythromycin), non-steroidal anti-inflammatory drugs (ibuprofen and diclofenac), a non-selective β-adrenoceptor blocker (propranolol), an antiepileptic drug (carbamazepine), and steroid estrogens (17β-estradiol and 17α-ethynylestradiol), were investigated in Taihu Lake, China. All eight PhACs were widely detected in surface water and sediment samples with maximal concentrations in the range of 8.74-118 ng L(-1) and 0.78-42.5 ng g(-1) dry weight (dw), respectively. The investigated organisms in the natural freshwater food web in Taihu Lake included phytoplankton, zooplankton, zoobenthos, and fish, and the maximal concentrations of target compounds in these biota samples ranged from 0.65 to 132 ng g(-1) dw. Bioaccumulation factors (BAFs) for all target PhACs were lower than 1000 L kg(-1), suggesting their low bioaccumulation potential in aquatic organisms from Taihu Lake. Trophic magnification factors (TMFs) were estimated at 1.11 for roxithromycin, 0.31 for propranolol, and 1.06 for diclofenac, indicating none of these PhACs underwent trophic magnification in this freshwater food web.

  16. Occurrence of antibiotics in water, sediments, aquatic plants, and animals from Baiyangdian Lake in North China.

    PubMed

    Li, Wenhui; Shi, Yali; Gao, Lihong; Liu, Jiemin; Cai, Yaqi

    2012-11-01

    This study investigated the presence and distribution of 22 antibiotics, including eight quinolones, nine sulfonamides and five macrolides, in the water, sediments, and biota samples from Baiyangdian Lake, China. A total of 132 samples were collected in 2008 and 2010, and laboratory analyses revealed that antibiotics were widely distributed in the lake. Sulfonamides were the dominant antibiotics in the water (0.86-1563 ng L(-1)), while quinolones were prominent in sediments (65.5-1166 μg kg(-1)) and aquatic plants (8.37-6532 μg kg(-1)). Quinolones (17.8-167 μg kg(-1)) and macrolides [from below detection limit (BDL) to 182 μg kg(-1)] were often found in aquatic animals and birds. Salvinia natans exhibited the highest bioaccumulation capability for quinolones among three species of aquatic plants. Geographical differences of antibiotic concentrations were greatly due to anthropogenic activities. Sewage discharged from Baoding City was likely the main source of antibiotics in the lake. Risk assessment of antibiotics on aquatic organisms suggested that algae and aquatic plants might be at risk in surface water, while animals were likely not at risk.

  17. Field application of a biofilm reactor based BOD prototype in Taihu Lake, China.

    PubMed

    Liu, Changyu; Dong, Shaojun

    2013-05-15

    A tubular biofilm reactor (BFR) based online biochemical oxygen demand prototype was applied in Taihu Lake, China. Municipal tap water was used instead of conventional phosphate buffer as blank solution to avoid phosphate pollution. The background organic compounds in municipal tap water were taken into account and they were validated to result in negative deviation to accuracy. The microbial endogenous respiration was experimentally validated to be sensitive to salt ionic strength, and municipal tap water as blank was thought to generate positive deviation to accuracy. The system was continuously operated over 2 months without man intervention, and the automated monitoring data agreed well with that of the conventional BOD5 methods. The BFR resisted the frequent measurements with samples of high turbidity, and the BOD monitoring data indicated the index of biodegradable organic compounds of Taihu Lake was accorded with the second class described in the environmental quality standard of surface water. Analyzed together with permanganate index on site, Taihu Lake was revealed to be of good capacity of self cleaning. Importantly, field application study of new BOD method made it more objective in evaluating its applicability, and could provide practical information and useful improvements in the process of commercializing.

  18. The Relationship between Phytoplankton Evenness and Copepod Abundance in Lake Nansihu, China

    PubMed Central

    Tian, Wang; Zhang, Huayong; Zhao, Lei; Xu, Xiang; Huang, Hai

    2016-01-01

    The relationship between biodiversity and ecosystem functioning is a central issue in ecology. Previous studies have shown that producer diversity can impact the consumer community via predator-prey interactions. However, direct observations of this relationship remain rare, in particular for aquatic ecosystems. In this research, the relationship between phytoplankton diversity (species richness and evenness) and the abundance of copepods was analyzed in Lake Nansihu, a meso-eutrophic lake in China. The results showed that copepods abundance was significantly decreased with increasing phytoplankton evenness throughout the year. However, both species richness and phytoplankton biomass showed no significant relationship with the abundance of copepods. Canonical correspondence analysis revealed that phytoplankton evenness was negatively correlated with Thermocyclops kawamurai, Cyclops vicinus, Eucyclops serrulatus, Mesocyclops leuckarti, Sinocalanus tenellus, Sinocalanus dorrii, Copepods nauplius, but positively correlated with many Cyanophyta species (Chroococcus minutus, Dactylococcopsis acicularis, Microcystis incerta, Merismopedia tenuissima, Merismopedia sinica and Lyngbya limnetica). Based on our results, phytoplankton evenness was a better predictor of copepods abundance in meso-eutrophic lakes. These results provide new insights into the relationship between diversity and ecosystem functioning in aquatic ecosystems. PMID:27589782

  19. Biodiversity effects on resource use efficiency and community turnover of plankton in Lake Nansihu, China.

    PubMed

    Tian, Wang; Zhang, Huayong; Zhang, Jian; Zhao, Lei; Miao, Mingsheng; Huang, Hai

    2017-03-15

    The relationship between biodiversity and ecosystem functioning is a central issue in ecology, especially in aquatic ecosystems due to the ecophysiological characteristics of plankton. Recently, ecologists have obtained conflicting conclusions while analyzing the influence of species diversity on plankton resource use efficiency (RUE) and community turnover. In this study, both phytoplankton and zooplankton communities were investigated seasonally from 2011 to 2013 in Lake Nansihu, a meso-eutrophic and recovering lake in China. The effects of phytoplankton diversity on RUE of phytoplankton (RUEPP), zooplankton (RUEZP), and community turnover were analyzed. Results showed that both phytoplankton species richness and evenness were positively correlated with RUEPP. RUEZP had a negative relationship with phytoplankton species richness, but a weak unimodal relationship with phytoplankton evenness. Cyanobacteria community had the opposite influence on RUEPP and RUEZP. Thus, cyanobacteria dominance will benefit RUEPP in eutrophic lakes, but the growth and reproduction of zooplankton are greatly limited. The strong negative relationship between total phosphorus and RUEZP confirmed these results. Phytoplankton community turnover tended to decrease with increasing phytoplankton evenness, which was consistent with most previous studies. The correlation coefficient between phytoplankton species richness and community turnover was negative, but not significant (p > 0.05). Therefore, phytoplankton community turnover was more sensitive to the variation of evenness than species richness. These results will be helpful in understanding the effects of species diversity on ecosystem functioning in aquatic ecosystems.

  20. Assessment of Heavy Metal Pollution in Sediments of Inflow Rivers to Lake Taihu, China.

    PubMed

    Niu, Yong; Niu, Yuan; Pang, Yong; Yu, Hui

    2015-11-01

    Lake Taihu, the third-largest freshwater body in China, has many functions, including drinking water supply, flood control, cultivation, navigation, and tourism. In this study, sediment samples were collected at 31 sites from 11 inflow rivers in 2012, to investigate the distribution and concentration of heavy metals copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), and chromium (Cr), and to assess their potential ecological risk. The highest mean concentration was found for Zn, followed by Cu, Cr, Pb, and Ni. Generally, heavy metal pollution was more serious in Wu Jingang River and Caoqiao River, probably because they receive large amounts of wastewater from various local industrial enterprises. The potential ecological risk values of the heavy metals were larger than 120 in more than 25.8% of the sediment samples, indicating a very high risk. The largest ecological risk was due to copper. Furthermore, the results of a principal component analysis and subsequent analysis of variance showed that heavy metal concentrations in the sediment of inflow rivers were higher than those of the lake, which created a large hazard for the aquatic ecosystems of Lake Taihu.

  1. Trace element accumulation in bivalve mussels Anodonta woodiana from Taihu Lake, China.

    PubMed

    Liu, Hongbo; Yang, Jian; Gan, Juli

    2010-11-01

    Data are presented for 13 trace metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, and Pb) in 38 bivalve mussels Anodonta woodiana from four separate sites (Huzhou, Dapu, Sansandao, and Manshan) around the Taihu Lake of China. All elemental concentrations generally ranked in decreasing order, Mn > Fe > Zn > As ≈ Cu ≈ Cd ≈ Se > Pb > Mo ≈ Ag, except that Cr, Co, and Ni were not detected. Anodonta woodiana was able to bioaccumulate essential Mn and toxic Cd to the extremely high level of 19,240 and 53 mg/kg dry weight, respectively. Geographical differences in the concentrations of trace elements were usually significant between sampling sites except for As and Pb, and the mussels from Sanshandao site had mostly accumulated or were contaminated with essential and toxic elements. The residue level of Cd in A. woodiana from the Sanshandao and Manshan sites appeared to be even higher than those of the essential elements Cu and Se, and exceeded the corresponding maximum residue limits of China. The present study provides the most recent information on trace element bioaccumulation or contamination in Taihu Lake and, further, suggests that A. woodiana can be used as a suitable bioindicator for inland water environmental monitoring.

  2. A double-cycle lake basin formed in extensional to transtensional setting: The Paleogene Nanpu Sag, Bohai Bay Basin, China

    NASA Astrophysics Data System (ADS)

    Zhang, Jianguo; Jiang, Zaixing; Gierlowski-Kordesch, Elizabeth; Xian, Benzhong; Li, Zhenpeng; Wang, Siqi; Wang, Xiabin

    2017-03-01

    It has been known that both extensional and transtensional tectonics commonly trigger a one-cycle evolution of lake sediments, but lake-cycle development co-controlled by extensional and transtensional tectonics still need identification. Here we report a double-cycle of lake sediments formed in extensional to transtensional phases in the Paleogene Nanpu Sag of the Bohai Bay Basin, China. The sag successively experienced five phases of lake-type evolution, characterized by: 1) overfilled, 2) balanced-fill, 3) overfilled, 4) balanced-fill, and 5) overfilled. Extensional tectonics was responsible for the opening of the basin and the initial creation of accommodation (1st through 3rd phase). Next, subsidence increased again through transtensional tectonics resulting in the creation of new accommodation (4th-5th phases). Investigations show this double-cycle lake-type evolution is also present in other lake-basins with similar tectonic settings (e.g., both extensional and transtensional tectonics). A different exploration and exploitation strategy should be devoted to the double-cycle evolution of lake basins controlled by extensional to transtensional tectonics in comparison to the single-cycle evolution in extensional or transtensional lake basins.

  3. Malaria Elimination Campaigns in the Lake Kariba Region of Zambia: A Spatial Dynamical Model

    PubMed Central

    Nikolov, Milen; Bever, Caitlin A.; Upfill-Brown, Alexander; Hamainza, Busiku; Miller, John M.; Eckhoff, Philip A.; Wenger, Edward A.; Gerardin, Jaline

    2016-01-01

    As more regions approach malaria elimination, understanding how different interventions interact to reduce transmission becomes critical. The Lake Kariba area of Southern Province, Zambia, is part of a multi-country elimination effort and presents a particular challenge as it is an interconnected region of variable transmission intensities. In 2012–13, six rounds of mass test-and-treat drug campaigns were carried out in the Lake Kariba region. A spatial dynamical model of malaria transmission in the Lake Kariba area, with transmission and climate modeled at the village scale, was calibrated to the 2012–13 prevalence survey data, with case management rates, insecticide-treated net usage, and drug campaign coverage informed by surveillance. The model captured the spatio-temporal trends of decline and rebound in malaria prevalence in 2012–13 at the village scale. Various interventions implemented between 2016–22 were simulated to compare their effects on reducing regional transmission and achieving and maintaining elimination through 2030. Simulations predict that elimination requires sustaining high coverage with vector control over several years. When vector control measures are well-implemented, targeted mass drug campaigns in high-burden areas further increase the likelihood of elimination, although drug campaigns cannot compensate for insufficient vector control. If infections are regularly imported from outside the region into highly receptive areas, vector control must be maintained within the region until importations cease. Elimination in the Lake Kariba region is possible, although human movement both within and from outside the region risk damaging the success of elimination programs. PMID:27880764

  4. Malaria Elimination Campaigns in the Lake Kariba Region of Zambia: A Spatial Dynamical Model.

    PubMed

    Nikolov, Milen; Bever, Caitlin A; Upfill-Brown, Alexander; Hamainza, Busiku; Miller, John M; Eckhoff, Philip A; Wenger, Edward A; Gerardin, Jaline

    2016-11-01

    As more regions approach malaria elimination, understanding how different interventions interact to reduce transmission becomes critical. The Lake Kariba area of Southern Province, Zambia, is part of a multi-country elimination effort and presents a particular challenge as it is an interconnected region of variable transmission intensities. In 2012-13, six rounds of mass test-and-treat drug campaigns were carried out in the Lake Kariba region. A spatial dynamical model of malaria transmission in the Lake Kariba area, with transmission and climate modeled at the village scale, was calibrated to the 2012-13 prevalence survey data, with case management rates, insecticide-treated net usage, and drug campaign coverage informed by surveillance. The model captured the spatio-temporal trends of decline and rebound in malaria prevalence in 2012-13 at the village scale. Various interventions implemented between 2016-22 were simulated to compare their effects on reducing regional transmission and achieving and maintaining elimination through 2030. Simulations predict that elimination requires sustaining high coverage with vector control over several years. When vector control measures are well-implemented, targeted mass drug campaigns in high-burden areas further increase the likelihood of elimination, although drug campaigns cannot compensate for insufficient vector control. If infections are regularly imported from outside the region into highly receptive areas, vector control must be maintained within the region until importations cease. Elimination in the Lake Kariba region is possible, although human movement both within and from outside the region risk damaging the success of elimination programs.

  5. Regional ground deformation and its controlling measures in China

    NASA Astrophysics Data System (ADS)

    Zhou, Zhifang; Zhu, Haisheng; Huang, Yong

    2006-12-01

    With the development of construction of China Cities, there exist a lot of environmental geological problems involved in the geofracture, land subsidence, collapse, landslide, devolution, mudrock flow, floating sand, piping and soft ground deformation. Of big cities whose population is over one million in China, about 30 cities appears the land subsidence region. Other cities locate in the regions of collapse yellow earth or expand soil of strong swell-shrink charasteristic, soft ground and karst. In the paper, the cause and hazard of regionality ground deformation is summed up. The causes of regional land deformation caused by the natural geological effect and activities of human being are analyzed. According to the length of deformation course and endanger of society, economy and life, land deformation involves three types, that is, the delay, rapid and break land deformation. And the concrete countermeasure and method are provided.

  6. Recruitment synchrony of yellow perch (Perca flavescens, Percidae) in the Great Lakes region, 1966–2008

    USGS Publications Warehouse

    Honsey, Andrew E.; Bunnell, David; Troy, Cary D.; Fielder, David G.; Thomas, Michael V.; Knight, Carey T.; Chong, Stephen; Hook, Tomas O.

    2016-01-01

    Population-level reproductive success (recruitment) of many fish populations is characterized by high inter-annual variation and related to annual variation in key environmental factors (e.g., climate). When such environmental factors are annually correlated across broad spatial scales, spatially separated populations may display recruitment synchrony (i.e., the Moran effect). We investigated inter-annual (1966–2008) variation in yellow perch (Perca flavescens, Percidae) recruitment using 16 datasets describing populations located in four of the five Laurentian Great Lakes (Erie, Huron, Michigan, and Ontario) and Lake St. Clair. We indexed relative year class strength using catch-curve residuals for each year-class across 2–4 years and compared relative year-class strength among sampling locations. Results indicate that perch recruitment is positively synchronized across the region. In addition, the spatial scale of this synchrony appears to be broader than previous estimates for both yellow perch and freshwater fish in general. To investigate potential factors influencing relative year-class strength, we related year-class strength to regional indices of annual climatic conditions (spring-summer air temperature, winter air temperature, and spring precipitation) using data from 14 weather stations across the Great Lakes region. We found that mean spring-summer temperature is significantly positively related to recruitment success among Great Lakes yellow perch populations.

  7. Rise of China in the Caribbean: Impacts for Regional Security

    DTIC Science & Technology

    2013-12-13

    Caribbean security, this study seeks to explore China’s motives and ascertain whether any gradual erosion of US geopolitical influence in the region may...geopolitical interests and Caribbean security, this study seeks to explore China’s motives and ascertain whether any gradual erosion of US geopolitical...affect current regional security arrangements? Will the expansion of China and the perceived erosion of US geopolitical influence in the Caribbean

  8. Hydrogeochemical evaluation of conventional and hot dry rock geothermal resource potential in the Clear Lake region, California

    SciTech Connect

    Goff, F.; Adams, A.I.; Trujillo, P.E.; Counce, D.

    1993-05-01

    Chemistry, stable isotope, and tritium contents of thermal/mineral waters in the Clear Lake region were used to evaluate conventional and hot dry rock (HDR) geothermal potential for electrical generation. Thermal/mineral waters of the Clear Lake region are broadly classified as thermal meteoric and connate types based on chemical and isotopic criteria. Ratios of conservative components such as B/Cl are extremely different among all thermal/mineral waters of the Clear Lake region except for clusters of waters emerging from specific areas such as the Wilbur Springs district and the Agricultural Park area south of Mt. Konocti. In contrast ratios of conservative components in large, homogeneous geothermal reservoirs are constant. Stable isotope values of Clear Lake region waters show a mixing trend between thermal meteoric and connate (generic) end-members. The latter end-member has enriched {delta}D as well as enriched {delta}{sup 18}O, from typical high-temperature geothermal reservoir waters. Tritium data indicate most Clear Lake region waters are mixtures of old and young fluid components. Subsurface equilibration temperature of most thermal/mineral waters of the Clear Lake region is {le}150{degree}C based on chemical geothermometers but it is recognized that Clear Lake region waters are not typical geothermal fluids and that they violate rules of application of many geothermometers. The combined data indicate that no large geothermal reservoir underlies the Clear Lake region and that small localized reservoirs have equilibration temperatures {le}150{degree}C (except for Sulphur Bank mine). HDR technologies are probably the best way to commercially exploit the known high-temperatures existing beneath the Clear Lake region particularly within and near the main Clear Lake volcanic field.

  9. The Late Pleistocene climatic optimum in the eastern Arctic region: Evidence from El'gygytgyn Lake

    NASA Astrophysics Data System (ADS)

    Lozhkin, A. V.; Anderson, P. M.; Minyuk, P. S.; Nedorubova, E. Yu.; Goryachev, N. A.

    2015-08-01

    The palynological investigations of sediments of the crater of El'gygytgyn Lake (67°30' N, 172°05' E), which provided a continuous record of interglacial and glacial events in Polar Chukotka, revealed significant climate warming corresponding to Marine Isotope Stage 31 (MIS 31) lasting from 1.062 to 1.081Ma ago. Its upper limit is placed within the Jaramillo paleomagnetic episode (0.99-1.07 Ma) registered in the sedimentary section of the lake. During MIS 31, the vegetation community was dominated by Betula- Alnus forests with subordinate Larix trees. These forests included also coniferous ( Picea, Pinus) and broad-leaved trees and shrubs ( Quercus, Carpinus, Corylus). The interglacial of MIS 31 was characterized by the warmest climate for the entire Quaternary Period. The warming episode established in the continuous record of the section of El'gygytgyn Lake implies relations between climatic events in the Arctic and Antarctic regions.

  10. Hydraulic fracturing and the Crooked Lake Sequences: Insights gleaned from regional seismic networks

    NASA Astrophysics Data System (ADS)

    Schultz, Ryan; Stern, Virginia; Novakovic, Mark; Atkinson, Gail; Gu, Yu Jeffrey

    2015-04-01

    Within central Alberta, Canada, a new sequence of earthquakes has been recognized as of 1 December 2013 in a region of previous seismic quiescence near Crooked Lake, ~30 km west of the town of Fox Creek. We utilize a cross-correlation detection algorithm to detect more than 160 events to the end of 2014, which is temporally distinguished into five subsequences. This observation is corroborated by the uniqueness of waveforms clustered by subsequence. The Crooked Lake Sequences have come under scrutiny due to its strong temporal correlation (>99.99%) to the timing of hydraulic fracturing operations in the Duvernay Formation. We assert that individual subsequences are related to fracturing stimulation and, despite adverse initial station geometry, double-difference techniques allow us to spatially relate each cluster back to a unique horizontal well. Overall, we find that seismicity in the Crooked Lake Sequences is consistent with first-order observations of hydraulic fracturing induced seismicity.

  11. Spatiotemporal trends of mercury in walleye and largemouth bass from the Laurentian Great Lakes region.

    PubMed

    Monson, Bruce A; Staples, David F; Bhavsar, Satyendra P; Holsen, Thomas M; Schrank, Candy S; Moses, Sara K; McGoldrick, Daryl J; Backus, Sean M; Williams, Kathryn A

    2011-10-01

    The risk of mercury (Hg) exposure to humans and wildlife from fish consumption has driven extensive mercury analysis throughout the Great Lakes Region since the 1970s. This study compiled fish-Hg data from multiple sources in the region and assessed spatiotemporal trends of Hg concentrations in two representative top predator fish species. Walleye (Sander vitreus) and largemouth bass (Micropterus salmoides) were chosen for the trend analysis because they had more Hg records (63,872) than other fish species that had been sampled from waters throughout the region. Waterbody types were inland lakes (70%), the Great Lakes, impoundments, and rivers. The compiled datasets were analyzed with a mixed effects statistical model having random effects of station, year, and fish length; and fixed effects of year, tissue type, fish length, habitat, and season. The results showed a generally declining temporal trend in fish-Hg for the region (1970-2009), with spatial trends of increasing Hg concentration from south to north and from west to east across the region. Nonlinearity was evident in the general downward trends of Ontario walleye, with a shift to an upward trend beginning in the 1990s. Only ongoing monitoring can reveal if this upward shift is an oscillation in a long-term decline, a statistical anomaly, or a sustained declining temporal trend in regional fish-Hg concentrations.

  12. Public Perception of Blue-Algae Bloom Risk in Hongze Lake of China

    NASA Astrophysics Data System (ADS)

    Huang, Lei; Sun, Kai; Ban, Jie; Bi, Jun

    2010-05-01

    In this work we characterize the public perception of one kind of ecological risk—blue-algae bloom in Hongze Lake, China, based on the psychometric paradigm method. In the first survey of May 2008, 300 respondents of Sihong County adjacent to Hongze Lake were investigated, with a total of 156 questionnaires returned. Then in a second survey of July 2008, 500 respondents from the same research area were investigated, with 318 questionnaires collected. This research firstly attempted to explore the local respondents’ degree of concern regarding ecological changes to Hongze Lake in the last ten years. Secondly, to explore the public perception of blue-algae bloom compared to three typical kinds of hazards including earthquake, nuclear power and public traffic. T-test was used to examine the difference of risk perception in these four hazards over time. The third part of this research, with demographic analysis and nonparametric statistical test, predicted the different groups of respondents’ willingness to accept (WTA) risk of blue-algae bloom in two surveys. Using multiple linear regression analysis, the risk perception model explained 28.3% of variance in the WTA blue-algae bloom risk. The variables of Knowledge, Social effect, Benefit, Controllability and Trust in government were significantly correlated with WTA, which implied that these variables were the main influencing factors explaining the respondents’ willingness to accept risk. The results would help the Chinese government to comprehend the public’s risk perception of the lake ecosystem, inducing well designed communication of risks with public and making effective mitigation policies to improve people’s rational risk judgment.

  13. Phylogenetic inference of colony isolates comprising seasonal Microcystis blooms in Lake Taihu, China.

    PubMed

    Otten, Timothy G; Paerl, Hans W

    2011-11-01

    Blooms of the toxin-producing cyanobacterium, Microcystis spp., are an increasingly prevalent water quality problem and health hazard worldwide. China's third largest lake, Lake Taihu, has been experiencing progressively more severe Microcystis blooms over the past three decades. In 2009 and 2010, individual Microcystis colonies, consisting of four different morphospecies, were isolated and genotyped using a whole-cell multiplex PCR assay. The 16S-23S rDNA-ITS sequences were aligned based on Bayesian inference and indicated that one morphospecies was genetically unique (Microcystis wesenbergii) and three were indistinguishable (Microcystis aeruginosa, Microcystis flos-aquae, and Microcystis ichthyoblabe). Microcystin (mcyB) genes were detected intermittently in two of the morphospecies while the other two morphospecies lacked the mcyB gene in all samples. Water temperature was found to influence bloom formation and morphotype prevalence, and chlorophyll a and temperature were positively and significantly correlated with microcystin concentration. Cooler water temperatures promoted toxigenic strains of Microcystis. Wind appeared to influence the distribution of morphotypes across the lake, with M. aeruginosa and M. ichthyoblabe being more susceptible to wind stress than M. wesenbergii and M. flos-aquae. The results of this study indicated that the blooms were composed of a variety of Microcystis morphospecies, with more genotypes observed than can be attributed to individual morphotypes. We conclude that morphology is not a reliable indicator of toxigenicity in Lake Taihu, and caution should be exercised when the M. aeruginosa morphotype is present because it is capable of producing MC-LR, the most toxic microcystin isoform.

  14. Public perception of blue-algae bloom risk in Hongze Lake of China.

    PubMed

    Huang, Lei; Sun, Kai; Ban, Jie; Bi, Jun

    2010-05-01

    In this work we characterize the public perception of one kind of ecological risk-blue-algae bloom in Hongze Lake, China, based on the psychometric paradigm method. In the first survey of May 2008, 300 respondents of Sihong County adjacent to Hongze Lake were investigated, with a total of 156 questionnaires returned. Then in a second survey of July 2008, 500 respondents from the same research area were investigated, with 318 questionnaires collected. This research firstly attempted to explore the local respondents' degree of concern regarding ecological changes to Hongze Lake in the last ten years. Secondly, to explore the public perception of blue-algae bloom compared to three typical kinds of hazards including earthquake, nuclear power and public traffic. T-test was used to examine the difference of risk perception in these four hazards over time. The third part of this research, with demographic analysis and nonparametric statistical test, predicted the different groups of respondents' willingness to accept (WTA) risk of blue-algae bloom in two surveys. Using multiple linear regression analysis, the risk perception model explained 28.3% of variance in the WTA blue-algae bloom risk. The variables of Knowledge, Social effect, Benefit, Controllability and Trust in government were significantly correlated with WTA, which implied that these variables were the main influencing factors explaining the respondents' willingness to accept risk. The results would help the Chinese government to comprehend the public's risk perception of the lake ecosystem, inducing well designed communication of risks with public and making effective mitigation policies to improve people's rational risk judgment.

  15. Fukien region, China (summary): terrain intelligence

    USGS Publications Warehouse

    ,

    1944-01-01

    Population of the Fukien region is estimated from census figures (1928-1935) for Fukien, Kiangsi, Chekiang, and Kwangtung Pro vlnces at 15 to 20 ipillion. At the coast are several important cities: Min-hou (390,363 inhabitants), Ssu-ming (219,974), Pfu-tlien, Chin-chiang, and Lung-chfi. Nmerous towns and villages are scattered throughout the region. - B. Climate is wann humid temperate in the north and hmid subtropical in the south. Typhoons occur in late summer, especially in the area from Min-hu north. Precipitation averages 40 to 80 inches per year; It is generally highest in the interior. Mean monthly tamperature range is 55O to 850 F at coast; greater range inland

  16. Physiological refugia: swamps, hypoxia tolerance and maintenance of fish diversity in the Lake Victoria region.

    PubMed

    Chapman, Lauren J; Chapman, Colin A; Nordlie, Frank G; Rosenberger, Amanda E

    2002-11-01

    In Lake Nabugabo, Uganda, a satellite of Lake Victoria, approximately 50% of the indigenous fishes disappeared from the open waters subsequent to the establishment of the introduced predatory Nile perch, Lates niloticus. This pattern is similar to the faunal loss experienced in the much larger Lake Victoria. Several of these species persisted in wetland refugia (e.g. ecotonal wetlands, swamp lagoons); however, deep swamp refugia (habitats lying well within the dense interior of fringing wetlands), are available only to a subset of the basin fauna with extreme tolerance to hypoxia. Although air-breathers are common in deep swamp refugia; we also documented a surprisingly high richness and abundance of non-air-breathing fishes. We describe several mechanisms that may facilitate survival in deep swamp refugia including high hemoglobin concentration, high hematocrit, large gill surface area and a low critical oxygen tension (P(c)). In addition, swamp-dwelling fishes showed lower PO(2) thresholds for onset of aquatic surface respiration than the lake-dwelling fishes. This suggests higher tolerance to hypoxia in the swamp fishes because they are able to withstand a lower oxygen tension before approaching the surface. We suggest that physiological refugia may be important in modulating the impact of Nile perch and indigenous fishes in the Lake Nabugabo region; this highlights the need to evaluate relative tolerance of introduced predators and indigenous prey to environmental stressors.

  17. Probabilistic projections of regional climatic changes over the Great Lakes Basin

    NASA Astrophysics Data System (ADS)

    Wang, Xiuquan; Huang, Guohe; Baetz, Brian W.; Zhao, Shan

    2016-11-01

    As the largest surface fresh water system on earth, the Great Lakes is facing the threat of climate change. Understanding how the hydrologic cycle in the Great Lakes region would be affected by human-induced global warming is important for developing informed adaptation strategies. In this study, high-resolution regional climate ensemble simulations based upon the PRECIS modeling system are conducted to project future climatic changes over the Great Lakes Basin. The results show that the Great Lakes Basin is very likely to experience a continuous warming-up throughout the 21st century. Particularly, mean air temperatures will rise by 2.6 °C in the forthcoming decades (i.e., 2030s), 3.8 °C in the middle of the century (i.e., 2050s), and 5.6 °C to the end of the century (i.e., 2080s), respectively. The warming air temperatures are very likely to result in more precipitation over the entire basin. The annual total precipitation over the Great Lakes Basin is projected to increase by 8.9% in the 2030s and 12.2% in the 2050s, while the magnitude of precipitation increase would decline to 7.1% in the 2080s. The slow-down of the precipitation increase from the 2050s to the 2080s indicates a shift from the aggressive increase of precipitation before and in the middle of this century to the eventual decrease by the end of this century, suggesting that a nonlinear response relationship between precipitation and temperature may exist in the Great Lakes Basin and such a relationship is also likely to vary in response to global warming.

  18. Methane efflux from littoral vegetation stands of southern boreal lakes: An upscaled regional estimate

    NASA Astrophysics Data System (ADS)

    Bergström, Irina; Mäkelä, Suvi; Kankaala, Paula; Kortelainen, Pirkko

    We studied the role of vegetated littoral area in the efflux of methane (CH 4) in a southern boreal landscape (1600 km 2), in Finland, covered by 619 lakes. A regression model was constructed to describe the relationship between lake area or lake shoreline length and total macrophyte or total emergent macrophyte coverage. Phragmites australis and Equisetum fluviatile were by far the most widely distributed emergent macrophytes in the area with a proportion of 40% of all zone-forming macrophytes. The zone-forming floating-leaved species Nuphar lutea, Potamogeton natans and Sparganium spp. covered 44% of all vegetated littoral areas. The strong temperature dependence of the emission rates was taken into consideration in the emission estimations for P. australis and E. fluviatile. The regional efflux, estimated for the growing seasons 1998-2002, varied between 0.8×10 5 and 1.1×10 5 kg CH 4 and between 1.6×10 5 and 2.4×10 5 kg CH 4, respectively. The emissions from the stands of floating-leaved species were negligible compared to the emissions from stands of P. australis and E. fluviatile. This indicates that species specific emission rates and areal coverage of the dominating species, as well as ambient temperature, should all be carefully considered when estimating the total regional emissions of CH 4 from lake littorals. The natural open ombrogenous bogs and minerogenous fens in the study region covered a 2.5-fold larger area than P. australis and E. fluviatile littoral, but their emissions were estimated to be only 78% of the emissions of P. australis and E. fluviatile, indicating that vegetated lake littoral is an important natural CH 4 source in the region.

  19. Potential Economic Impacts from Offshore Wind in the Great Lakes Region (Fact Sheet)

    SciTech Connect

    Tegen, S.; Keyser, D.

    2014-01-01

    Offshore wind is a clean, renewable source of energy and can be an economic driver in the United States. To better understand the employment opportunities and other potential regional economic impacts from offshore wind development, the U.S. Department of Energy (DOE) funded research that focuses on four regions of the country. The studies use multiple scenarios with various local job and domestic manufacturing content assumptions. Each regional study uses the new offshore wind Jobs and Economic Development Impacts (JEDI) model, developed by DOE's National Renewable Energy Laboratory. This fact sheet summarizes the potential economic impacts identified by the study for the Great Lakes region.

  20. Late Miocene episodic lakes in the arid Tarim Basin, western China

    PubMed Central

    Liu, Weiguo; Liu, Zhonghui; An, Zhisheng; Sun, Jimin; Chang, Hong; Wang, Ning; Dong, Jibao; Wang, Huanye

    2014-01-01

    The Tibetan Plateau uplift and Cenozoic global cooling are thought to induce enhanced aridification in the Asian interior. Although the onset of Asian desertification is proposed to have started in the earliest Miocene, prevailing desert environment in the Tarim Basin, currently providing much of the Asian eolian dust sources, is only a geologically recent phenomenon. Here we report episodic occurrences of lacustrine environments during the Late Miocene and investigate how the episodic lakes vanished in the basin. Our oxygen isotopic (δ18O) record demonstrates that before the prevailing desert environment, episodic changes frequently alternating between lacustrine and fluvial-eolian environments can be linked to orbital variations. Wetter lacustrine phases generally corresponded to periods of high eccentricity and possibly high obliquity, and vice versa, suggesting a temperature control on the regional moisture level on orbital timescales. Boron isotopic (δ11B) and δ18O records, together with other geochemical indicators, consistently show that the episodic lakes finally dried up at ∼4.9 million years ago (Ma), permanently and irreversibly. Although the episodic occurrences of lakes appear to be linked to orbitally induced global climatic changes, the plateau (Tibetan, Pamir, and Tianshan) uplift was primarily responsible for the final vanishing of the episodic lakes in the Tarim Basin, occurring at a relatively warm, stable climate period. PMID:25368156

  1. Late Miocene episodic lakes in the arid Tarim Basin, western China.

    PubMed

    Liu, Weiguo; Liu, Zhonghui; An, Zhisheng; Sun, Jimin; Chang, Hong; Wang, Ning; Dong, Jibao; Wang, Huanye

    2014-11-18

    The Tibetan Plateau uplift and Cenozoic global cooling are thought to induce enhanced aridification in the Asian interior. Although the onset of Asian desertification is proposed to have started in the earliest Miocene, prevailing desert environment in the Tarim Basin, currently providing much of the Asian eolian dust sources, is only a geologically recent phenomenon. Here we report episodic occurrences of lacustrine environments during the Late Miocene and investigate how the episodic lakes vanished in the basin. Our oxygen isotopic (δ(18)O) record demonstrates that before the prevailing desert environment, episodic changes frequently alternating between lacustrine and fluvial-eolian environments can be linked to orbital variations. Wetter lacustrine phases generally corresponded to periods of high eccentricity and possibly high obliquity, and vice versa, suggesting a temperature control on the regional moisture level on orbital timescales. Boron isotopic (δ(11)B) and δ(18)O records, together with other geochemical indicators, consistently show that the episodic lakes finally dried up at ∼4.9 million years ago (Ma), permanently and irreversibly. Although the episodic occurrences of lakes appear to be linked to orbitally induced global climatic changes, the plateau (Tibetan, Pamir, and Tianshan) uplift was primarily responsible for the final vanishing of the episodic lakes in the Tarim Basin, occurring at a relatively warm, stable climate period.

  2. Land use impacts on lake water quality in Alytus region (Lithuania)

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Laukonis, Rymvidas

    2016-04-01

    Land use has important impacts on soils, surface and ground water quality. Urban agricultural areas are an important source of pollutants, which can reach lakes through surface runoff and underground circulation. Human intervention in the landscape is one of the major causes pollution and land degradation, thus it is very important to understand the impacts of and use on environment and if they have some spatial pattern (Pereira et al., 2013, 2015; Brevik et al., 2016). The identification of the spatial pattern of lakes pollution is in Alytus area (Lithuania) is fundamental, since they provide an important range of ecosystem services to local communities, including food and recreational activities. Thus, the degradation of these environments can induce important economic losses. In this context, it is import to identify the areas with high pollutant accumulation and the environmental and human factors responsible for it. The objective of this work is to study identify the amount of some important nutrients resultant from human activities in lake water quality in Alytus region (Lithuania). Alytus region is located in southern part of Lithuania and has an approximate area of 40 km2. Inside this region we analyzed several water quality parameters of 55 lakes, including, pH, electrical conductivity (EC), suspended materials (SM), water clarity (WC) biochemical oxygen demand (BDO), total phosphorous (TP), total Nitrogen (TN), dissolved organic carbon (DOC), as other environmental variables as altitude, lake maximum deep (MD), lake area and land use according Corine land cover classification (CLC2006). Previous to data analysis, data normality and homogeneity of the variances, was assessed with the Shapiro-wilk and Leven's test, respectively. The majority of the data did not respect the Gaussian distribution and the heteroscedasticity, even after a logarithmic, and box-cox transformation. Thus, in this work we used the logarithmic transformed data to do a principal

  3. Highly Pathogenic Avian Influenza A(H5N8) Virus in Wild Migratory Birds, Qinghai Lake, China.

    PubMed

    Li, Mingxin; Liu, Haizhou; Bi, Yuhai; Sun, Jianqing; Wong, Gary; Liu, Di; Li, Laixing; Liu, Juxiang; Chen, Quanjiao; Wang, Hanzhong; He, Yubang; Shi, Weifeng; Gao, George F; Chen, Jianjun

    2017-04-01

    In May 2016, a highly pathogenic avian influenza A(H5N8) virus strain caused deaths among 3 species of wild migratory birds in Qinghai Lake, China. Genetic analysis showed that the novel reassortant virus belongs to group B H5N8 viruses and that the reassortment events likely occurred in early 2016.

  4. Highly Pathogenic Avian Influenza A(H5N8) Virus in Wild Migratory Birds, Qinghai Lake, China

    PubMed Central

    Li, Mingxin; Liu, Haizhou; Bi, Yuhai; Sun, Jianqing; Wong, Gary; Liu, Di; Li, Laixing; Liu, Juxiang; Chen, Quanjiao; Wang, Hanzhong; He, Yubang; Shi, Weifeng; Gao, George F.

    2017-01-01

    In May 2016, a highly pathogenic avian influenza A(H5N8) virus strain caused deaths among 3 species of wild migratory birds in Qinghai Lake, China. Genetic analysis showed that the novel reassortant virus belongs to group B H5N8 viruses and that the reassortment events likely occurred in early 2016. PMID:28169827

  5. ARMA-model-based region-growing method for extracting lake region in a remote sensing image

    NASA Astrophysics Data System (ADS)

    Chen, Chi H.; Ho, Peter Pei-Gee

    2004-02-01

    Recently the lake area detection has been a popular topic for time series remote sensing images analysis. The two-dimensional Markov model is one of the efficient mathematical models to describe an image especially when the within-object interpixel correlation varies significantly from object to object. The unsupervised Region Growing is a powerful image segmentation method for use in shape classification and analysis. In this paper, the Region Growing method based on two-dimensional Autoregressive Moving Average (ARMA) model is proposed for lake region detections. Some of the statistical techniques, such as Gaussian distributed white noise error confidence interval, and sample statistics based on mean and variance properties have been used for thresholding during calculations. The linear regression analysis with least mean squares estimation is still of ongoing interest for statistical research and applications especially with the remote sensing images. The LANDSAT 5 database in the area of Italy's Lake Mulargias acquired in July 1996 was used for the computing experiments with satisfactory preliminary results.

  6. The Influence of Macrophytes on Sediment Resuspension and the Effect of Associated Nutrients in a Shallow and Large Lake (Lake Taihu, China)

    PubMed Central

    Zhu, Mengyuan; Zhu, Guangwei; Nurminen, Leena; Wu, Tingfeng; Deng, Jianming; Zhang, Yunlin; Qin, Boqiang; Ventelä, Anne-Mari

    2015-01-01

    A yearlong campaign to examine sediment resuspension was conducted in large, shallow and eutrophic Lake Taihu, China, to investigate the influence of vegetation on sediment resuspension and its nutrient effects. The study was conducted at 6 sites located in both phytoplankton-dominated zone and macrophyte-dominated zone of the lake, lasting for a total of 13 months, with collections made at two-week intervals. Sediment resuspension in Taihu, with a two-week high average rate of 1771 g·m-2·d-1 and a yearly average rate of 377 g·m-2·d-1, is much stronger than in many other lakes worldwide, as Taihu is quite shallow and contains a long fetch. The occurrence of macrophytes, however, provided quite strong abatement of sediment resuspension, which may reduce the sediment resuspension rate up to 29-fold. The contribution of nitrogen and phosphorus to the water column from sediment resuspension was estimated as 0.34 mg·L-1 and 0.051 mg·L-1 in the phytoplankton-dominated zone. Sediment resuspension also largely reduced transparency and then stimulated phytoplankton growth. Therefore, sediment resuspension may be one of the most important factors delaying the recovery of eutrophic Lake Taihu, and the influence of sediment resuspension on water quality must also be taken into account by the lake managers when they determine the restoration target. PMID:26030094

  7. A numerical modeling study of the coupled variability of Lake Victoria in eastern Africa and the regional climate

    NASA Astrophysics Data System (ADS)

    Song, Yi

    2000-12-01

    The objective of this investigation was to investigate and study the coupled atmosphere-lake climate system over the Lake Victoria basin, and determine the corresponding physical mechanisms that are involved. The primary research vehicle for the investigation is a fully coupled model of the regional climate of Eastern Africa and Lake Victoria which has been developed and applied in this study. The atmospheric component of the model is the NCAR Regional Climate Model (RegCM2). The results show that the bythemetry and geometry of the lake play a fundamental role in determining the climatology of Lake Victoria. There exists Kelvin-like waves in the thermocline trapped along the coast and they propagate clockwise around Lake Victoria with periodicity of about 30 days. Preliminary comparison of the coupled RegCM2-POM model simulation results with the observations indicates that the model produces more realistic lake surface temperatures (LST) and rainfall over and around the lake than the standard version of RegCM2 in which a simple one dimensional thermal diffusion lake model is used. Over Eastern Africa, the regional climate variability is significantly influenced by the circulation over the Lake Victoria basin. The interaction between the lake-land breeze and the prevailing northeasterly flow accounts for the asymmetry in the distribution of the diurnal rainfall variations and the southwestward movement of the dominant bands of divergence/convergence. During the 1982 El Nino when the averaged LST over the lake was higher than that during the normal year, the LST gradient was weakened along the SW-NE axis over the lake by the strong lake circulation. The hydrodynamics of the lake play an important role in determining the coupled variability of the lake circulation and the lake basin-wide climatic conditions. The potential climate change resulting from total clearing of the tropical rain forests in Africa was also investigated by the standard version of the NCAR CCM3

  8. Tectonic controls on magmatism in the Geysers-Clear Lake region: Evidence from new geophysical models

    USGS Publications Warehouse

    Stanley, W.D.; Benz, H.M.; Walters, M.A.; Villasenor, A.; Rodriguez, B.D.

    1998-01-01

    In order to study magmatism and geothermal systems in The Geysers-Clear Lake region, we developed a detailed three-dimensional tomographic velocity model based on local earthquakes. This high-resolution model resolves the velocity structure of the crust in the region to depths of approximately 12 km. The most significant velocity contrasts in The Geysers-Clear Lake region occur in the steam production area, where high velocities are associated with a Quaternary granitic pluton, and in the Mount Hannah region, where low velocities occur in a 5-km-thick section of Mesozoic argillites. In addition, a more regional tomographic model was developed using traveltimes from earthquakes covering most of northern California. This regional model sampled the whole crust, but at a lower resolution than the local model. The regional model outlines low velocities at depths of 8-12 km in The Geysers-Clear Lake area, which extend eastward to the Coast Range thrust. These low velocities are inferred to be related to unmetamorphosed Mesozoic sedimentary rocks. In addition, the regional velocity model indicates high velocities in the lower crust beneath the Clear Lake volcanic field, which we interpret to be associated with mafic underplating. No large silicic magma chamber is noted in either the local or regional tomographic models. A three-dimensional gravity model also has been developed in the area of the tomographic imaging. Our gravity model demonstrates that all density contrasts can be accounted for in the upper 5-7 km of the crust. Two-dimensional magnetotelluric models of data from a regional, east-west profile indicate high resistivities associated with the granitic pluton in The Geysers production area and low resistivities in the low-velocity section of Mesozoic argillites near Mount Hannah. No indication of midcrustal magma bodies is present in the magnetotelluric data. On the basis of heat flow and geologic evidence, Holocene intrusive activity is thought to have

  9. Regional patterns of soil organic carbon stocks in China.

    PubMed

    Yu, D S; Shi, X Z; Wang, H J; Sun, W X; Chen, J M; Liu, Q H; Zhao, Y C

    2007-11-01

    Soil organic carbon (SOC) is of great importance in the global carbon cycle. Distribution patterns of SOC in various regions of China constitute a nation-wide baseline for studies on soil carbon changes. This paper presents an integrated and multi-level study on SOC stock patterns of China, and presents baseline SOC stock estimates by great administrative regions, river watersheds, soil type regions and ecosystem. The assignment is done by means of a recently completed 1: 1,000,000 scale soil database of China, which is the most detailed and reliable one in China at the present time. SOC densities of 7292 soil profiles collected across China in the middle of the 1980s were calculated and then linked to corresponding polygons in a digital soil map, resulting in a SOC Density Map of China on a 1: 1,000,000 scale, and a 1 km x 1 km grid map. Corresponding maps of administrative regions, river watersheds, soil types (ST), and ecosystems in China were also prepared with an identical resolution and coordinate control points, allowing GIS analyses. Results show that soils in China cover an area of 9.281 x 10(6)km(2) in total, with a total SOC stock of 89.14 Pg (1 Pg=10(15)g) and a mean SOC density of 96.0 t C/ha. Confidence limits of the SOC stock and density in China are estimated as [89.23 Pg, 89.08 Pg] and [96.143 t C/ha, 95.981 t C/ha] at 95% probability, respectively. The largest total SOC stock (23.60 Pg) is found in South-west China while the highest mean SOC density (181.9 t C/ha) is found in north-east China. The total SOC stock and the mean SOC density in the Yangtze river watershed are 21.05 Pg and 120.0 t C/ha, respectively, while the corresponding figures in the Yellow river watershed are 8.46 Pg and 104.3 t C/ha, respectively. The highest total SOC stocks are found in Inceptisols (34.39 Pg) with SOC density of 102.8 t C/ha. The lowest and highest mean SOC densities are found on Entisols (28.1 t C/ha), and on Histosols (994.728.1 t C/ha), respectively

  10. Paleoproterozoic basin development and sedimentation in the Lake Superior region, North America

    USGS Publications Warehouse

    Ojakangas, R.W.; Morey, G.B.; Southwick, D.L.

    2001-01-01

    The peneplaned Archean craton in the Lake Superior region was the platform upon which a continental margin assemblage was deposited. Extension resulted in localized rifts that received thicker accumulations of sediments and volcanic rocks than did adjacent parts of the platform. Seas transgressed onto the continent several times and an ocean basin opened south of the present-day Lake Superior. Island arcs that formed during subduction collided with the craton margin as the ocean basin closed; oceanic crust is poorly preserved as a dismembered ophiolite sequence. The arc volcanics are preserved as the Wisconsin magmatic terranes. The collision resulted in a fold-and-thrust belt known as the Penokean orogen. To the north of the fold-and-thrust belt, a northward-migrating foreland basin - the Animikie basin - developed. Thick turbidite successions were deposited along the basin axis, and terrigenous clastics and Lake Superior-type iron-formation were deposited on the shelf along the northern margin of the basin. The primary paleoclimatic indicators are: (1) glaciogenic rocks at the base of the Paleoproterozoic succession in Michigan indicating ice-house conditions; 2) remnants of a paleosol on the glaciogenic rocks indicative of deep weathering, probably under subtropical conditions and therefore of greenhouse conditions; and (3) carbonate minerals after gypsum, halite, and anhydrite in stromatolitic dolomite, indicative of aridity. Three second-order depositional sequences are bounded by major unconformities, and can be correlated throughout the Lake Superior region. ?? 2001 Elsevier Science B.V. All rights reserved.

  11. Preliminary Gravity and Magnetic Data of the Lake Pillsbury Region, Northern Coast Ranges, California

    USGS Publications Warehouse

    Langenheim, V.E.; Jachens, Robert C.; Morin, Robert L.; McCabe, Craig A.

    2007-01-01

    The Lake Pillsbury region is transected by the Bartlett Springs Fault zone, one of the main strike-slip faults of the San Andreas system north of San Francisco Bay, California. Gravity and magnetic data were collected to help characterize the geometry and offset of the fault zone as well as determine the geometry of the Gravelly Valley pull-apart basin and Potter Valley, an alluvial intermontane basin southwest of Lake Pillsbury. The Bartlett Springs fault zone lies at the base of a significant gravity gradient. Superposed on the gradient is a small gravity low centered over Lake Pillsbury and Gravelly Valley. Another small gravity low coincides with Potter Valley. Inversion of gravity data for basin thickness indicates a maximum thickness of 400 and 440 m for the Gravelly and Potter Valley depressions, respectively. Ground magnetic data indicate that the regional aeromagnetic data likely suffer from positional errors, but that large, long-wavelength anomalies, sourced from serpentinite, may be offset 8 km along the Bartlett Springs Fault zone. Additional gravity data collected either on the lake surface or bottom and in Potter Valley would better determine the shape of the basins. A modern, high-resolution aeromagnetic survey would greatly augment the ability to map and model the fault geometry quantitatively.

  12. Regional ground-water flow modeling of the Glacial Lake Agassiz Peatlands, Minnesota

    NASA Astrophysics Data System (ADS)

    Reeve, A. S.; Warzocha, J.; Glaser, P. H.; Siegel, D. I.

    2001-03-01

    Three-dimensional ground-water modeling experiments were done to test the hypothesis that regional ground-water flow is an important component of the water budget in the Glacial Lake Agassiz Peatlands of northern Minnesota. Previous data collected from the Glacial Lake Agassiz Peatlands suggest that regional ground-water flow discharges to these peatlands, maintaining saturation, controlling the peat pore-water chemistry, and driving ecological change. To test this hypothesis, steady-state MODFLOW models were constructed that encompassed an area of 10,160 km 2. Data used in this modeling project included surface-water and water-table elevations measured across the study area, digital elevation data, and well logs from scientific test wells and domestic water wells drilled in the study area. Numerical simulations indicate that the Itasca Moraine, located to the south of the peatland, acts as a recharge area for regional ground-water flow. Ground water recharged at the Itasca Moraine did not discharge to the Red Lake Peatlands, but rather was intercepted by the Red Lakes or adjacent rivers. Simulations suggest that ground-water flow within the peatlands consists of local-flow systems with streamlines that are less than 10 km long and that ground water from distant recharge areas does not play a prominent role in the hydrology of these peatlands. Ground-water flow reversals previously observed in the Red Lake Peatlands are either the result of interactions between local and intermediate-scale flow systems or the transient release of water stored in glacial sediments when the water-table is lowered.

  13. A new biogeochemical model to simulate regional scale carbon emission from lakes, ponds and wetlands

    NASA Astrophysics Data System (ADS)

    Bayer, Tina; Brakebusch, Matthias; Gustafsson, Erik; Beer, Christian

    2016-04-01

    Small aquatic systems are receiving increasing attention for their role in global carbon cycling. For instance, lakes and ponds in permafrost are net emitters of carbon to the atmosphere, and their capacity to process and emit carbon is significant on a landscape scale, with a global flux of 8-103 Tg methane per year which amounts to 5%-30% of all natural methane emissions (Bastviken et al 2011). However, due to the spatial and temporal highly localised character of freshwater methane emissions, fluxes remain poorly qualified and are difficult to upscale based on field data alone. While many models exist to model carbon cycling in individual lakes and ponds, we perceived a lack of models that can work on a larger scale, over a range of latitudes, and simulate regional carbon emission from a large number of lakes, ponds and wetlands. Therefore our objective was to develop a model that can simulate carbon dioxide and methane emission from freshwaters on a regional scale. Our resulting model provides an additional tool to assess current aquatic carbon emissions as well as project future responses to changes in climatic drivers. To this effect, we have combined an existing large-scale hydrological model (the Variable Infiltration Capacity Macroscale Hydrologic Model (VIC), Liang & Lettenmaier 1994), an aquatic biogeochemical model (BALTSEM, Savchuk et al., 2012; Gustafsson et al., 2014) and developed a new methane module for lakes. The resulting new process-based biogeochemical model is designed to model aquatic carbon emission on a regional scale, and to perform well in high-latitude environments. Our model includes carbon, oxygen and nutrient cycling in lake water and sediments, primary production and methanogenesis. Results of calibration and validation of the model in two catchments (Torne-Kalix in Northern Sweden and of a large arctic river catchment) will be presented.

  14. The surface energy budget and interannual variation of the annual total evaporation over a highland lake in Southwest China

    NASA Astrophysics Data System (ADS)

    Feng, Jian Wu; Liu, Hui Zhi; Sun, Ji Hua; Wang, Lei

    2016-10-01

    The turbulence spectra and energy budget were investigated based on eddy covariance method over an open-water highland lake (Erhai Lake) in Southwest China. We estimated the annual total evaporation and CO2 emission from the lake, and the evaporation trend in the past few decades was also discussed. Due to the large thermal inertia of lake water, the surface water temperature lagged behind the air temperature. Maximum lake-air temperature difference of about 4 °C had been observed in November. Water temperature profile measurements revealed that the stratification of lake water was not evident throughout the year. The spectra and cospectra of wind speed and temperature roughly satisfied the -2/3 and -4/3 rule in inertial subrange, respectively. The w spectra were observed to have a larger contribution from higher frequencies than other variables. Obvious shifts of spectra and cospectra peaks toward higher frequencies were observed as the atmospheric stratification became more stable. The lake acted as a heat sink from March through June and quickly released heat into the atmosphere from September through December. Average energy balance closure for the lake was about 80 % in 2012. The lake majorly acted as a source of CO2 to the atmosphere, but weak sinks of CO2 were observed in the summer and early fall. The total annual emission of CO2 was estimated to be 333.28 g C m-2 year-1. The annual evaporation over the lake decreased due to the increased amount of low cloud and precipitation, with the lower annual evaporation in the 1990s compared to that in the 1980s.

  15. An inventory of glacial lakes in the Third Pole region and their changes in response to global warming

    NASA Astrophysics Data System (ADS)

    Dai, Y.; Zhang, G.; Yao, T.; Xie, H.

    2015-12-01

    No glacial lake census exists for the Third Pole region, which includes the Pamir-Hindu Kush-Karakoram-Himalayas and the Tibetan Plateau. Therefore, comprehensive information is lacking about the distribution of and changes in glacial lakes caused by current global warming conditions. In this study, the first glacial lake inventories for the Third Pole were conducted for ~1990, 2000, and 2010 using Landsat TM/ETM+ data. Glacial lake spatial distributions, corresponding areas and temporal changes were examined. The significant results are as follows. (1) There were 4602, 4981, and 5701 glacial lakes (> 0.003 km2) covering areas of 553.9 ± 90, 581.2 ± 97, and 682.4 ± 110 km2 in ~1990, 2000, and 2010, respectively; these lakes are primarily located in the Brahmaputra (39%), Indus (28%), and Amu Darya (10%) basins. (2) Small lakes (< 0.2 km2) are more sensitive to climate changes. (3) Lakes closer to glaciers and at higher altitudes, particularly those connected to glacier termini, have undergone larger area changes. (4) Glacier-fed lakes are dominant in both quantity and area (> 70%) and exhibit faster expansion trends overall compared to non-glacier-fed lakes. We conclude that glacier meltwater may play a dominant role in the areal expansion of most glacial lakes in the Third Pole. In addition, the patterns of the glacier-fed lakes correspond well with warming temperature trends and negative glacier mass balance patterns. This paper presents an important database of glacial lakes and provides a basis for long-term monitoring and evaluation of outburst flood disasters primarily caused by glacial lakes in the Third Pole.

  16. An inventory of glacial lakes in the Third Pole region and their changes in response to global warming

    NASA Astrophysics Data System (ADS)

    Zhang, Guoqing; Yao, Tandong; Xie, Hongjie; Wang, Weicai; Yang, Wei

    2015-08-01

    No glacial lake census exists for the Third Pole region, which includes the Pamir-Hindu Kush-Karakoram-Himalayas and the Tibetan Plateau. Therefore, comprehensive information is lacking about the distribution of and changes in glacial lakes caused by current global warming conditions. In this study, the first glacial lake inventories for the Third Pole were conducted for ~ 1990, 2000, and 2010 using Landsat TM/ETM + data. Glacial lake spatial distributions, corresponding areas and temporal changes were examined. The significant results are as follows. (1) There were 4602, 4981, and 5701 glacial lakes (> 0.003 km2) covering areas of 553.9 ± 90, 581.2 ± 97, and 682.4 ± 110 km2 in ~ 1990, 2000, and 2010, respectively; these lakes are primarily located in the Brahmaputra (39%), Indus (28%), and Amu Darya (10%) basins. (2) Small lakes (< 0.2 km2) are more sensitive to climate changes. (3) Lakes closer to glaciers and at higher altitudes, particularly those connected to glacier termini, have undergone larger area changes. (4) Glacier-fed lakes are dominant in both quantity and area (> 70%) and exhibit faster expansion trends overall compared to non-glacier-fed lakes. We conclude that glacier meltwater may play a dominant role in the areal expansion of most glacial lakes in the Third Pole. In addition, the patterns of the glacier-fed lakes correspond well with warming temperature trends and negative glacier mass balance patterns. This paper presents an important database of glacial lakes and provides a basis for long-term monitoring and evaluation of outburst flood disasters primarily caused by glacial lakes in the Third Pole.

  17. Micropaleontological Record of Post-glacial History in Lake Champlain and Adjacent Regions: Implications for Glacial Lake Drainage and Abrupt Climate Events

    NASA Astrophysics Data System (ADS)

    Cronin, T. M.; Manley, P. L.; Guilbault, J.; Berke, M.; Rayburn, J. A.; Franzi, D. A.; Knuepfer, P. L.

    2005-12-01

    Post-glacial lacustrine and marine sediments of the Lake Champlain region range from 20 to >50 meters in thickness presenting an opportunity to assess the timing of North American glacial lake drainage at multidecadal timescales and evaluate its effect on North Atlantic salinity and abrupt climate events 13.5 to 10 kyr B.P. High-resolution analysis of foraminifera and ostracodes from cores taken onshore in the Plattsburgh, N.Y. vicinity and southern Quebec and offshore in southern Lake Champlain reveal complex changes in salinity during and after the transition from pro-glacial Lake Vermont (Lake Candona in Canada) to marine sedimentation in the Champlain Sea. The microfaunal sequence (bottom to top) includes: non-marine ostracodes ( Candona) in lacustrine varves, foraminiferal assemblages (common Cassidulina reniforme), another interval of Candona-bearing sediments (sometimes containing foraminifera), and, finally, sediments from the main phase of the Champlain sea episode containing diverse foraminiferal and marine ostracode assemblages. A decrease in salinity during the Champlain Sea is also in evidence from the shift in dominance of distinct variants of Elphidium in the deep basin. The marine episode ended with a progressive salinity decrease and the formation of Lake Champlain about 10 kyr B.P. Observed salinity changes could be caused by catastrophic fresh-water influx from large glacial lakes west of the Lake Champlain region, meltwater from the retreating Laurentide Ice Sheet margin, diminished influx of marine water from the St. Lawrence due to changes in the position of the ice sheet margin and isostatic adjustment, or a combination of factors. The ages of these events were determined by estimating the reservoir effect on radiocarbon dates on marine shells through comparison with AMS dates on plant material and palynology, and shed light on the hypothesis that glacial lake discharges catalyzed abrupt climate events.

  18. Assessing Ecotourism from a Multi-stakeholder Perspective: Xingkai Lake National Nature Reserve, China

    NASA Astrophysics Data System (ADS)

    Su, Ming Ming; Wall, Geoffrey; Ma, Zhong

    2014-11-01

    Ecotourism development is closely associated with the sustainability of protected natural areas. When facilitated by appropriate management, ecotourism can contribute to conservation and development, as well as the well-being of local communities. As such, ecotourism has been proposed and practiced in different forms in many places, including China. This study assesses ecotourism development at Xingkai Lake National Nature Reserve in Heilongjiang Province, China. Key informant interviews were conducted with representatives from the provincial Forestry Department, the Nature Reserve, and the local community. Observation was undertaken on three site visits and secondary data were collected. The potential for providing quality natural experiences is high and tourism development is occurring rapidly. However, current relationships between people, resources, and tourism have yet to provide mutual benefits necessary for successful ecotourism. The multi-stakeholder management style and the ambiguity of landownership within the nature reserve constitute structural difficulties for ecotourism management and operation. Although participation in ecotourism could provide a livelihood opportunity and interests in involvement in tourism have been identified among the local fishing community, current involvement is limited mainly due to the lack of mechanisms for participation. Therefore, it is recommended that management programs and government policies should be established to provide a platform for community participation in ecotourism. Then, a positive synergistic relationship between tourism, environment, and community could be developed. Planning and policy requirements are discussed for ecotourism development in protected areas in China.

  19. Reconstruction of historical lead contamination and sources in Lake Hailing, Eastern China: a Pb isotope study.

    PubMed

    Zhang, Rui; Guan, Minglei; Shu, Yujie; Shen, Liya; Chen, Xixi; Zhang, Fan; Li, Tiegang; Jiang, Tingchen

    2016-05-01

    The history records of lead and its stable isotopic ratios were determined in a sediment core to receive anthropogenic impacts on the Lake Hailing in eastern China. The sediment core was dated based on (210)Pb, (137)Cs, and (239+240)Pu. The historical changes of Pb/Al and Pb isotope ratios showed increasing trend upward throughout the core, suggesting changes in energy usage and correlating closely with the experience of a rapid economic and industrial development of the catchment, Linyi City, in eastern China. Based on the mixing end member model of Pb isotope ratios, coal combustion emission dominated anthropogenic Pb sources in the half part of the century contributing 13 to 43 % of total Pb in sediment. Moreover, contributions of chemical and organic fertilizer were 1-13 and 5-14 %, respectively. In contrast, the contribution of leaded gasoline was low than 8 %. The results indicated that historical records of Pb contamination predominantly sourced from coal combustion and chemical and organic fertilizer in the catchment. In addition, an increase of coal combustion source and fertilizers was found throughout the sediment core, whereas the contribution of leaded gasoline had declined after 2000s, which is attributed to the phaseout of leaded gasoline in China.

  20. Assessing ecotourism from a multi-stakeholder perspective: Xingkai Lake National Nature Reserve, China.

    PubMed

    Su, Ming Ming; Wall, Geoffrey; Ma, Zhong

    2014-11-01

    Ecotourism development is closely associated with the sustainability of protected natural areas. When facilitated by appropriate management, ecotourism can contribute to conservation and development, as well as the well-being of local communities. As such, ecotourism has been proposed and practiced in different forms in many places, including China. This study assesses ecotourism development at Xingkai Lake National Nature Reserve in Heilongjiang Province, China. Key informant interviews were conducted with representatives from the provincial Forestry Department, the Nature Reserve, and the local community. Observation was undertaken on three site visits and secondary data were collected. The potential for providing quality natural experiences is high and tourism development is occurring rapidly. However, current relationships between people, resources, and tourism have yet to provide mutual benefits necessary for successful ecotourism. The multi-stakeholder management style and the ambiguity of landownership within the nature reserve constitute structural difficulties for ecotourism management and operation. Although participation in ecotourism could provide a livelihood opportunity and interests in involvement in tourism have been identified among the local fishing community, current involvement is limited mainly due to the lack of mechanisms for participation. Therefore, it is recommended that management programs and government policies should be established to provide a platform for community participation in ecotourism. Then, a positive synergistic relationship between tourism, environment, and community could be developed. Planning and policy requirements are discussed for ecotourism development in protected areas in China.

  1. Response of organic carbon burial to trophic level changes in a shallow eutrophic lake in SE China.

    PubMed

    Wu, Pengbao; Gao, Chao; Chen, Furong; Yu, Shiyong

    2016-08-01

    Lakes are an important component of terrestrial carbon cycling. As the trend of eutrophication in many lakes continues, the mechanisms of organic carbon (OC) burial remain unclear. This paper aims to understand the distribution of OC and the effect of trophic level changes on OC burial in Chaohu Lake, a shallow eutrophic lake located in the lower reaches of the Yangtze River, SE China. Two hundred and one surface sediment samples (0-20cm) and 53 subsurface samples (150-200cm) from the lake were collected. The OC accumulation rates (OCARs) are relatively low, with an average of 10.01g/m(2)/year in the surface sediments. The spatial distribution of the OCARs is similar to that of allochthonous OC. The difference in total phosphate (TP) content between the surface and subsurface sediments (ΔTP) is significantly correlated with the autochthonous OC, suggesting that TP loading is a critical limiting nutrient for the lake's primary productivity. It is concluded that allochthonous OC is the dominant source of total OC in surface sediments compared to autochthonous OC. The primary productivity of Lake Chaohu increased due to increasing nutrient loading. However, the autochthonous OC contributed 11% of the total OC in the surface sediments. This could be ascribed to strong mineralization in the water column or surface sediments.

  2. The impact of the African Great Lakes on the regional climate in a dynamically downscaled CORDEX simulation

    NASA Astrophysics Data System (ADS)

    Thiery, Wim; Panitz, Hans-Jürgen; Davin, Edouard; van Lipzig, Nicole

    2014-05-01

    Owing to the strong contrast in albedo, roughness and heat capacity between land and water, lakes significantly influence the exchange of moisture, heat and momentum between the surface and the boundary layer. To investigate this two-way interaction, a correct representation of lakes within regional climate models is essential. To this end, the one-dimensional lake parameterisation scheme FLake was recently coupled to the regional climate model COSMO-CLM (CCLM). One region where lakes constitute a key component of the climate system is the African Great Lakes region. In this study, the CCLM CORDEX-Africa evaluation simulation is dynamically downscaled from 0.44° (50 km) to 0.0625° (7 km) over East-Africa, an unprecedented resolution for this region. The performance of different CCLM configurations are compared for the period 1999-2008: in particular, CCLM is tested for its sensitivity to the choice of the lake surface temperature description (SST, FLake, an improved version of FLake and Hostetler) and the land surface model (Terra and Community Land Model). Model results are evaluated in a three-step procedure. First, the atmospheric state variables near-surface temperature, precipitation, surface energy fluxes, fractional cloud cover and column precipitable water are evaluated using in-situ based and satellite-derived products. Second, a comprehensive set of in-situ water temperature profile observations serves to evaluate the temporal evolution of water temperatures at three sites: Lake Kivu (Ishungu), Lake Tanganyika's northern basin (Kigoma) and southern basin (Mpulungu). Finally, spatial variability of surface temperatures in Lake Kivu and Lake Tanganyika are evaluated on the basis of satellite-derived lake surface temperatures. Subsequently, the preferred model configuration is used to quantify and understand effects by lakes reported for other regions in the world, such as a dampened diurnal temperature range, enhanced evaporation, modified surface layer

  3. Methyl and total mercury in precipitation in the Great Lakes region

    NASA Astrophysics Data System (ADS)

    Hall, B. D.; Manolopoulos, H.; Hurley, J. P.; Schauer, J. J.; St. Louis, V. L.; Kenski, D.; Graydon, J.; Babiarz, C. L.; Cleckner, L. B.; Keeler, G. J.

    Methylmercury (MeHg) and total mercury (THg) concentrations were measured in precipitation collected from five US sites in the Great Lakes region: three sites on the southern shore of Lake Superior (Brule River, WI, Eagle Harbor, MI, and Tahquamenon Falls, MI), one at Isle Royale National Park (MI), and one in southern Wisconsin (Devil's Lake), between May 1997 and December 2003. MeHg and THg concentrations at these sites were compared to MeHg and THg concentrations in precipitation collected at the Experimental Lakes Area (ELA) in north-western Ontario, Canada. Detectable MeHg concentrations (>0.01 ng L -1) were found in the majority of rain and snow samples collected from all sites (range=0.01-0.85 ng L -1). In general, the lowest MeHg concentrations were observed in samples taken at Tahquamenon Falls and the ELA, and the highest MeHg concentrations in precipitation were observed in samples collected from Brule River and Eagle Harbor. Total Hg concentrations in precipitation were generally between 10 and 60 ng L -1, exceeding 60 ng L -1 in one precipitation event sampled from each of Brule River, Isle Royale, Tahquamenon Falls, and Devil's Lake. The proportion of THg that was MeHg (%MeHg), was less than 6% at all sites, with the exception of seven events at Tahquamenon Falls and two events at the ELA that were between 6% and 18% MeHg. Generally, the highest MeHg concentrations were found in low-volume precipitation events (<100 mL). At Tahquamenon Falls, meteorological analysis indicated that events with higher MeHg concentrations and %MeHg exceeding 6% were generally associated with lake effect precipitation and weak local winds.

  4. Regional nitrogen budget of the Lake Victoria Basin, East Africa: syntheses, uncertainties and perspectives

    NASA Astrophysics Data System (ADS)

    Zhou, Minghua; Brandt, Patric; Pelster, David; Rufino, Mariana C.; Robinson, Timothy; Butterbach-Bahl, Klaus

    2014-10-01

    Using the net anthropogenic nitrogen input (NANI) approach we estimated the N budget for the Lake Victoria Basin in East Africa. The NANI of the basin ranged from 887 to 3008 kg N km-2 yr-1 (mean: 1827 kg N km-2 yr-1) for the period 1995-2000. The net nitrogen release at basin level is due primarily to livestock and human consumption of feed and foods, contributing between 69% and 85%. Atmospheric oxidized N deposition contributed approximately 14% to the NANI of the Lake Victoria Basin, while either synthetic N fertilizer imports or biological N fixations only contributed less than 6% to the regional NANI. Due to the low N imports of feed and food products (<20 kg N km-2 yr-1), nitrogen release to the watershed must be derived from the mining of soil N stocks. The fraction of riverine N export to Lake Victoria accounted for 16%, which is much lower than for watersheds located in Europe and USA (25%). A significant reduction of the uncertainty of our N budget estimate for Lake Victoria Basin would be possible if better data on livestock systems and riverine N export were available. Our study indicates that at present soil N mining is the main source of nitrogen in the Lake Victoria Basin. Thus, sustainable N management requires increasing agricultural N inputs to guarantee food security and rehabilitation and protection of soils to minimize environmental costs. Moreover, to reduce N pollution of the lake, improving management of human and animal wastes needs to be carefully considered in future.

  5. Incorporation of Complex Hydrological and Socio-economic Factors for Non-point Source Pollution Control: A Case Study at the Yincungang Canal, the Lake Tai Basin of China

    NASA Astrophysics Data System (ADS)

    Yang, X.; Luo, X.; Zheng, Z.

    2012-04-01

    It is increasingly realized that non-point pollution sources contribute significantly to water environment deterioration in China. Compared to developed countries, non-point source pollution in China has the unique characteristics of strong intensity and composition complexity due to its special socioeconomic conditions. First, more than 50% of its 1.3 billion people are rural. Sewage from the majority of the rural households is discharged either without or only with minimal treatment. The large amount of erratic rural sewage discharge is a significant source of water pollution. Second, China is plagued with serious agricultural pollution due to widespread improper application of fertilizers and pesticides. Finally, there lack sufficient disposal and recycling of rural wastes such as livestock manure and crop straws. Pollutant loads from various sources have far exceeded environmental assimilation capacity in many parts of China. The Lake Tai basin is one typical example. Lake Tai is the third largest freshwater lake in China. The basin is located in the highly developed and densely populated Yangtze River Delta. While accounting for 0.4% of its land area and 2.9% of its population, the Lake Tai basin generates more than 14% of China's Gross Domestic Production (GDP), and the basin's GDP per capita is 3.5 times as much as the state average. Lake Tai is vital to the basin's socio-economic development, providing multiple services including water supply for municipal, industrial, and agricultural needs, navigation, flood control, fishery, and tourism. Unfortunately, accompanied with the fast economic development is serious water environment deterioration in the Lake Tai basin. The lake is becoming increasingly eutrophied and has frequently suffered from cyanobacterial blooms in recent decades. Chinese government has made tremendous investment in order to mitigate water pollution conditions in the basin. Nevertheless, the trend of deteriorating water quality has yet to

  6. Survey of Archaeal Diversity in Sediments of Qinghai Lake, China and Implications for Paleoclimate Change

    NASA Astrophysics Data System (ADS)

    Ye, Q.; Jiang, H.; Ji, S.; Dong, H.; Zhang, C.

    2006-12-01

    Qinghai Lake, the largest inland saline lake in China, is located in the northeastern corner of Tibetan Plateau at an altitude of 3200 m above the sea level. Previous research suggests that sediments in Qinghai Lake may be a good recorder of changes in climate during the last 18,000 years. But it is not clear if microbial record can be used to help reconstruct paleoclimate. The goal of this study was to explore the relationship between archaeal microbial communities and paleoclimatic changes. A 5-m long sediment core was collected with a drilling rig and two subsamples from 0-10 cm and 345-355 cm depth intervals were used for this study. These two subsamples (corresponding to present and ~7 cal. Kyr BP, respectively) represent cold/arid and warm/wet conditions (Shen et al., 2004) . 16S archaeal rRNA gene and lipid biomarker analyses were performed on these two samples. The archaeal 16S rRNA gene fragments were PCR-amplified from extracted nucleic acids and cloned for sequence determination. A total of 90 clones were sequenced for the two samples studied. Rarefaction analysis indicated that the number of unique clones reached saturation. Phylogenetic analysis of both clone libraries revealed the presence of two major lineages, belonging to the Euryarchaeota and Crenarchaeota phyla. Sequences from different libraries formed distinct clusters in both phyla, and clonal sequences were not closely related to any known isolates. LIBSHUFF analysis displayed the significant dissimilarity of archaeal diversity between two studied samples. In addition, Crenarchaeotal biomarker (GDGT) was only detected in the top layer by lipid analyses.The crenarchaeotal abundance at the bottom sample may be below the detection limit and much lower than that of the top one. In summary, our results suggest that the composition and structure of archaeal community is significantly different under different climatic condition, and may affect the biological carbon cycling in this unique Qinghai

  7. Effect of wave-current interactions on sediment resuspension in large shallow Lake Taihu, China.

    PubMed

    Li, Yiping; Tang, Chunyan; Wang, Jianwei; Acharya, Kumud; Du, Wei; Gao, Xiaomeng; Luo, Liancong; Li, Huiyun; Dai, Shujun; Mercy, Jepkirui; Yu, Zhongbo; Pan, Baozhu

    2017-02-01

    The disturbance of the water-sediment interface by wind-driven currents and waves plays a critical role in sediment resuspension and internal nutrient release in large, shallow lakes. This study analyzed the effects of the interactions between wind-induced currents an1d waves on the driving mechanism of sediment resuspension in Lake Taihu, the third largest freshwater lake in China, using acoustic and optic techniques to collect long-term, high-frequency, synchronous in situ measurements of wind, currents, waves, and suspended solid concentrations (SSCs). The results suggested that water turbidity started to increase at wind speeds of approximately 4 m/s and significantly increased when wind speeds exceeded 6 m/s. In most cases, wind-induced waves were the main energy source for changes in turbidity. Wave-generated shear stress contributed more than 95% to sediment resuspension and that only in weak wind conditions (<4 m/s) did the lake bottom shear stresses generated by currents and waves contributed equally. The relationship between SSC and bottom shear stress generated by wave was established by fitting the observed results. The processes of sediment dynamics were divided into four stages (A through D) according to three shear-stress thresholds. In stage A, SSC remained stable (about 45 mg/L) and τw was less than 0.02 N/m(2). In stage B, the sediment bed was starting to be activated (SSC 45∼60 mg/L) and τw was in the range of 0.02∼0.07 N/m(2). In stage C, a medium amount of sediment was suspended (SSC 60∼150 mg/L) and τw ranged from 0.07 to 0.3 N/m(2). In stage D, large amount of sediment was suspended (SSC 150∼300 mg/L) and τw was larger than 0.3 N/m(2). The findings of this paper reveal the driving mechanism of sediment resuspension, which may further help to evaluate internal nutrient release in large shallow Lake Taihu.

  8. Spatial analysis on China's regional air pollutants and CO2 emissions: emission pattern and regional disparity

    NASA Astrophysics Data System (ADS)

    Dong, Liang; Liang, Hanwei

    2014-08-01

    China has suffered from serious air pollution and CO2 emission. Challenges of emission reduction policy not only come from technology advancement, but also generate from the fact that, China has pronounced disparity between regions, in geographical and socioeconomic. How to deal with regional disparity is important to achieve the reduction target effectively and efficiently. This research conducts a spatial analysis on the emission patterns of three air pollutants named SO2, NOx and PM2.5, and CO2, in China's 30 provinces, applied with spatial auto-correlation and multi regression modeling. We further analyze the regional disparity and inequity issues with the approach of Lorenz curve and Gini coefficient. Results highlight that: there is evident cluster effect for the regional air pollutants and CO2 emissions. While emission amount increases from western regions to eastern regions, the emission per GDP is in inverse trend. The Lorenz curve shows an even larger unequal distribution of GDP/emissions than GDP/capita in 30 regions. Certain middle and western regions suffers from a higher emission with lower GDP, which reveal the critical issue of emission leakage. Future policy making to address such regional disparity is critical so as to promote the emission control policy under the “equity and efficiency” principle.

  9. Applicability of three-band model for estimating chlorophyll-a concentration in two Asian lakes (Lake Kasumigaura, Japan and Lake Dianchi, China)

    NASA Astrophysics Data System (ADS)

    Matsushita, B.; Yang, W.; Chen, J.; Fukushima, T.

    2009-12-01

    Bunkei Matsushita1*, Wei Yang1, 2, Jin Chen2 and Takehiko Fukushima1 1Graduate School of Life and Environmental Sciences, University of Tsukuba 1-1-1 Tennoudai, Tsukuba, Ibaraki, 305-8572, Japan E-mails: mbunkei@sakura.cc.tsukuba.ac.jp, fukusima@sakura.cc.tsukuba.ac.jp 2 State key laboratory of earth surface processes and resource ecology, Beijing Normal University, Beijing 100875, China E-mails: chenjin@ires.cn, yangwei1022@gmail.com Abstract: The remote sensing of chlorophyll-a in case II water has been far less successful than that in case I water, due mainly to the complex interactions among optically active substances (i.e., phytoplankton, tripton, colored dissolved organic matter, and water) in the former. To address this problem, Gitelson et al. (2008) suggested a three-band model, which can minimize the effects of tripton, colored dissolved organic matter (CDOM), and pure water, and thus promised an accurate estimation of chlorophyll-a. In this study, we used three datasets with different phytoplankton species to test the performance of the three-band model developed by Gitelson et al. The major findings of our study were as follows: (1) the mechanism of the three-band model could work very well for each phytoplankton species (R2>0.84, rRMSE<23%); (2) the slope and intercept of the three-band model strongly depended on variation of phytoplankton species; (3) chlorophyll-specific absorption coefficients at 440 nm (a*ph(440)) could be used to predict the slope and intercept of the three-band model for different species of phytoplankton. Compared with the previous three-band model, the RMSEs of the improved three-band model were reduced from 37.2 mg m-3 to 7.3 mg m-3, and from 34.3 mg m-3 to 15.9 mg m-3, for Lake Kasumigaura, and Lake Dianchi, respectively. Keywords: phytoplankton species, field survey, tank experiment, bio-optical model, case II water

  10. Geochemistry of thermal/mineral waters in the Clear Lake region, California, and implications for hot dry rock geothermal development

    SciTech Connect

    Goff, F.; Adams, A.I.; Trujillo, P.E.; Counce, D.; Mansfield, J.

    1993-02-01

    Thermal/mineral waters of the Clear Lake region are broadly classified as thermal meteoric and connote types based on chemical and isotopic criteria. Ratios of conservative components such as B/Cl are extremely different among all thermal/mineral waters of the Clear Lake region except for clusters of waters emerging from specific areas such as the Wilbur Springs district and the Agricultural Park area south of Mt. Konocti. In contrast, ratios of conservative components in large, homogeneous geothermal reservoirs are constant. Stable isotope values of Clear Lake region waters show a mixing trend between thermal meteoric and connote end-members. The latter end-member has enriched [delta]D as well as enriched d[sup l8]O, very different from typical high-temperature geothermal reservoir waters. Tritium data and modeling of ages indicate most Clear Lake region waters are 500 to > 10,000 yr., although mixing of old and young components is implied by the data. The age of end-member connate water is probably > 10,000 yr. Subsurface equilibration temperature of most thermal/mineral waters of the Clear Lake region is [le] 150[degrees]C based on chemical geothermometers but it is recognized that Clear Lake region waters are not typical geothermal fluids and that they violate rules of application of many geothermometers. The combined data indicate that no large geothermal reservoir underlies the Clear Lake region and that small localized reservoirs have equilibration temperatures [le] 150[degrees]C (except for Sulphur Bank Mine). Hot dry rock technologies are the best way to commercially exploit the known high temperatures existing beneath the Clear Lake region, particularly within the main Clear Lake volcanic field.

  11. Aquatic ecological biochemical investigations in the Lake Baikal region

    SciTech Connect

    Timofeeva, S.S.; Kozhova, O.M.

    1986-07-01

    The authors maintain that at the current level of investigations a constructive solution of the problem of protecting aquatic ecosystems is possible only on the basis of a thorough study of biochemical mechanisms of the interaction of biota and pollutants. They believe that in the program of investigations in the Baikal region, with consideration of the easy vulnerability of the aquatic ecosystems, ecological biochemical investigations should occupy one of the leading places. The authors suggest a method for the screening of xenobiotics, consisting of xenobiotics; chemical investigations; biochemical investigations of the properties of xenobiotics, and toxicological investigations of xenobiotics. The differences in the elimination of xenobiotics are considerable due to the species and biochemical characteristics of hydrophytes and chemical structure of the investigated toxicants. The results obtained in experiments with cyanide compounds are of considerable interest, since cyanides, the strongest poisons of animals, prove to be little toxic for higher aquatic plants and algae.

  12. Tectonic controls on magmatism in The Geysers--Clear Lake region: Evidence from new geophysical models

    SciTech Connect

    Stanley, W.D.; Benz, H.M.; Villasenor, A.; Rodriguez, B.D.; Walters, M.A.

    1998-09-01

    In order to study magmatism and geothermal systems in the Geysers-Clear Lake region, the authors developed a detailed three-dimensional tomographic velocity model based on local earthquakes. This high-resolution model resolves the velocity structure of the crust in the region to depths of approximately 12 km. The most significant velocity contrasts in The Geysers-Clear Lake region occur in the steam production area, where high velocities are associated with a Quaternary granite pluton, and in the Mount Hannah region, where low velocities occur in a 5-km-thick section of Mesozoic argillites. In addition, a more regional tomographic model was developed using traveltimes from earthquakes covering most of northern California. This regional model sampled the whole crust, but at a lower resolution than the local model. No large silicic magma chamber is noted in either the local or regional tomographic models. A three-dimensional gravity model also has ben developed in the area of the tomographic imaging. The gravity model demonstrates that all density contrasts can be accounted for in the upper 5--7 km of the crust. Two-dimensional magnetotelluric models of data from a regional east-west profile indicate high resistivities associated with the granitic pluton in The Geysers production area and low resistivities in the low-velocity section of Mesozoic argillites near Mount Hannah. No indication of midcrustal magma bodies is present in the magnetotelluric data. The geophysical models, seismicity patterns, distribution of volcanic vents, heat flow, and other data indicate that small, young intrusive bodies that were injected along a northeast trend from The Geysers to Clear Lake probably control the thermal regime.

  13. Geologic hypotheses of Lake Tanganyika region, Zaire, drawn from ERTS imagery

    NASA Technical Reports Server (NTRS)

    Wolyce, U.; Ilunga, S.

    1974-01-01

    Based on initial work in the Lake Tanganyika area of eastern Zaire, it has been concluded that ERTS imagery is extremely useful for reconnaissance level geologic mapping and analysis in this region of the humid tropics. In particular, ERTS imagery has proven useful for recognizing and mapping regional structural units, for recognizing major structural features, and for arriving at some preliminary hypotheses about the mineral potential of the area. Results so far indicate that ERTS imagery can make a major contribution to the development of the mineral resources of the country. Research has concentrated on applications of ERTS imagery in the field of cartography, geology, forestry, hydrology and agriculture. For the work in geology, a test site was chosen in eastern Zaire on the shore of Lake Tanganyika in the vicinity of the Lukuga River. This area was selected because of its varied geology and the existence of two frames of cloud-free ERTS imagery.

  14. Great Lakes O shore Wind Project: Utility and Regional Integration Study

    SciTech Connect

    Sajadi, Amirhossein; Loparo, Kenneth A.; D'Aquila, Robert; Clark, Kara; Waligorski, Joseph G.; Baker, Scott

    2016-06-30

    This project aims to identify transmission system upgrades needed to facilitate offshore wind projects as well as operational impacts of offshore generation on operation of the regional transmission system in the Great Lakes region. A simulation model of the US Eastern Interconnection was used as the test system as a case study for investigating the impact of the integration of a 1000MW offshore wind farm operating in Lake Erie into FirstEnergy/PJM service territory. The findings of this research provide recommendations on offshore wind integration scenarios, the locations of points of interconnection, wind profile modeling and simulation, and computational methods to quantify performance, along with operating changes and equipment upgrades needed to mitigate system performance issues introduced by an offshore wind project.

  15. The regional and global significance of nitrogen removal in lakes and reservoirs

    USGS Publications Warehouse

    Harrison, J.A.; Maranger, R.J.; Alexander, R.B.; Giblin, A.E.; Jacinthe, P.-A.; Mayorga, Emilio; Seitzinger, S.P.; Sobota, D.J.; Wollheim, W.M.

    2009-01-01

    Human activities have greatly increased the transport of biologically available nitrogen (N) through watersheds to potentially sensitive coastal ecosystems. Lentic water bodies (lakes and reservoirs) have the potential to act as important sinks for this reactive N as it is transported across the landscape because they offer ideal conditions for N burial in sediments or permanent loss via denitrification. However, the patterns and controls on lentic N removal have not been explored in great detail at large regional to global scales. In this paper we describe, evaluate, and apply a new, spatially explicit, annual-scale, global model of lentic N removal called NiRReLa (Nitrogen Retention in Reservoirs and Lakes). The NiRReLa model incorporates small lakes and reservoirs than have been included in previous global analyses, and also allows for separate treatment and analysis of reservoirs and natural lakes. Model runs for the mid-1990s indicate that lentic systems are indeed important sinks for N and are conservatively estimated to remove 19.7 Tg N year-1 from watersheds globally. Small lakes (<50 km2) were critical in the analysis, retaining almost half (9.3 Tg N year -1) of the global total. In model runs, capacity of lakes and reservoirs to remove watershed N varied substantially at the half-degree scale (0-100%) both as a function of climate and the density of lentic systems. Although reservoirs occupy just 6% of the global lentic surface area, we estimate they retain ~33% of the total N removed by lentic systems, due to a combination of higher drainage ratios (catchment surface area:lake or reservoir surface area), higher apparent settling velocities for N, and greater average N loading rates in reservoirs than in lakes. Finally, a sensitivity analysis of NiRReLa suggests that, on-average, N removal within lentic systems will respond more strongly to changes in land use and N loading than to changes in climate at the global scale. ?? 2008 Springer Science

  16. Summary appraisals of the Nation's ground-water resources; Great Lakes region

    USGS Publications Warehouse

    Weist, William G.

    1978-01-01

    Efficient development and management of ground-water resources requires a through knowledge of the system. Reports on ground water are available for about 80 percent of tbe Great Lakes Region. Most of these reports, however, are not sufficiently detailed to be useful in comprehensive planning. As ground-water development continues, quantitative groundwater studies, utilizing models as predictive tools, will enable this development to proceed in an efficient manner.

  17. Organochlorine pesticides in fish from Taihu Lake, China, and associated human health risk assessment.

    PubMed

    Wang, Deqing; Yu, Yingxin; Zhang, Xinyu; Zhang, Dongping; Zhang, Shaohuan; Wu, Minghong

    2013-12-01

    Because contaminants and nutrients always coexist in fish, the risk from contaminants and the benefit from nutrients, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are also concomitant via fish consumption. To investigate the risk and benefit via fish consumption, concentrations of dichlorodiphenyltrichloroethane and its metabolites (DDTs), and hexachlorocyclohexanes (HCHs) in the whole- and portion-muscles of fish from Taihu Lake, China, were measured. Based on the contaminant data and nutrients from our previous study, and the associated risk and benefit via fish consumption were estimated. The concentrations of DDTs and HCHs in the whole-muscles ranged from 7.8 × 10² to 3.4×10³ pg g⁻¹ ww, and from 67.3 to 300 pg g⁻¹ ww, respectively. Of DDTs and HCHs measured, p,p'-DDE and β-HCH were respectively the most abundant pesticides. The composition profiles of DDTs and HCHs suggested that the pesticides were mainly historical residues. The benefit-risk quotient (BRQ) of EPA+DHA vs. POPs (persistent organic pollutants including data of DDTs, HCHs, and those of polychlorinated biphenyls and polybrominated diphenyl ethers cited from our previous study) via consumption of fish from Taihu Lake was calculated. As a result, to achieve the recommended EPA+DHA intake of 250 mg d⁻¹ for a healthy adult, the consumption of most fish species from the lake can cause cancer and non-cancer risks. However, the fish consumption at the rates of 44.9 g d⁻¹ by Chinese would not lead to the risks for most of the species. The results also suggested that the risk of consuming silver carp was generally lower than other fish species, and those of dorsal muscles were lower than ventral and tail muscles.

  18. Debris flows resulting from glacial-lake outburst floods in tibet, China

    USGS Publications Warehouse

    Cui, P.; Dang, C.; Cheng, Z.; Scott, K.

    2010-01-01

    During the last 70 years of general climatic amelioration, 18 glacial-lake outburst floods (GLOFs) and related debris flows have occurred from 15 moraine-dammed lakes in Tibet, China. Catastrophic loss of life and property has occurred because of the following factors: the large volumes of water discharged, the steep gradients of the U-shaped channels, and the amount and texture of the downstream channel bed and bank material. The peak discharge of each GLOF exceeded 1000 m3/s. These flood discharges transformed to non-cohesive debris flows if the channels contained sufficient loose sediment for entrainment (bulking) and if their gradients were >1%. We focus on this key element, transformation, and suggest that it be included in evaluating future GLOF-related risk, the probability of transformation to debris flow and hyperconcentrated flow. The general, sequential evolution of the flows can be described as from proximal GLOFs, to sedimentladen streamflow, to hyperconcentrated flow, to non-cohesive debris flow (viscous or cohesive debris flow only if sufficient fine sediment is present), and then, distally, back to hyperconcentrated flow and sediment-laden streamflow as sediment is progressively deposited. Most of the Tibet examples transformed only to non-cohesive debris flows. The important lesson for future hazard assessment and mitigation planning is that, as a GLOF entrains (bulks) enough sediment to become a debris flow, the flow volume must increase by at least three times (the "bulking factor"). In fact, the transforming flow waves overrun and mix with downstream streamflow, in addition to adding the entrained sediment (and thus enabling addition of yet more sediment and a bulking factor in excess of three times). To effectively reduce the risk of GLOF debris flows, reducing the level of a potentially dangerous lake with a siphon or excavated spillway or installing gabions in combination with a downstream debris dam are the primary approaches.

  19. A DPSIR Model for Ecological Security Assessment through Indicator Screening: A Case Study at Dianchi Lake in China

    PubMed Central

    Wang, Zhen; Zhou, Jingqing; Loaiciga, Hugo; Guo, Huaicheng; Hong, Song

    2015-01-01

    Given the important role of lake ecosystems in social and economic development, and the current severe environmental degradation in China, a systematic diagnosis of the ecological security of lakes is essential for sustainable development. A Driving-force, Pressure, Status, Impact, and Risk (DPSIR) model, combined with data screening for lake ecological security assessment was developed to overcome the disadvantages of data selection in existing assessment methods. Correlation and principal component analysis were used to select independent and representative data. The DPSIR model was then applied to evaluate the ecological security of Dianchi Lake in China during 1988-2007 using an ecological security index. The results revealed a V-shaped trend. The application of the DPSIR model with data screening provided useful information regarding the status of the lake’s ecosystem, while ensuring information efficiency and eliminating multicollinearity. The modeling approach described here is practical and operationally efficient, and provides an attractive alternative approach to assess the ecological security of lakes. PMID:26107170

  20. Seismicity and Tectonics of the Lake Tahoe Basin through the Truckee, California Region

    NASA Astrophysics Data System (ADS)

    Seaman, T.; Ruhl, C. J.; Schmauder, G. C.; Smith, K. D.

    2013-12-01

    East dipping range bounding normal faults, NE-trending sinistral, and NW-trending dextral strike-slip faults of the Tahoe-Truckee, California-Nevada area define the transtensional strain environment of the Northern Walker Lane. North of Long Valley, California, the Sierran front is comprised of a series of left-stepping normal faults that terminate in the northern Lake Tahoe basin area. Directly north of Lake Tahoe, slip is transferred through the Truckee, California area and northward through a complex distribution of primarily conjugate strike-slip and minor normal fault systems. The recent identification of the Polaris fault zone extends Northern Walker Lake Belt dextral slip south of the Mohawk Valley fault zone to Truckee. The region accommodates as much as 10 mm/yr of dextral shear and has a history of M6+ earthquakes. In contrast to the general lack of background seismicity associated with major range bounding normal faults in the Tahoe region, there is abundant seismicity north of the Lake through this slip transfer zone (i.e., focal mechanisms of small magnitude earthquakes provide limited constraints on the dips of major range bounding normal faults). A NE-SW-trending zone of seismicity north of Lake Tahoe and extending into southeast Reno, Nevada, includes several M4+ strike-slip and normal faulting sequences, and numerous identifiable structures. An M4.5 (2004), M4.8 (2005), and associated general increase in seismicity in the N. Tahoe area may have been triggered by broader deformation resulting from a Moho-depth dike injection event in late 2003 (von Seggern et al., 2008). Preliminary analysis of short-period focal mechanisms reveals a change in T-axis trend from ESE west of the California-Nevada border to ENE east of the border. Focal mechanism and moment tensor solutions produce a ratio of 9/1 strike-slip to normal solutions in contrast to range bounding east dipping normal structures. Earthquake relocations display distinct lineaments of seismicity

  1. The decline process and major pathways of Microcystis bloom in Taihu Lake, China

    NASA Astrophysics Data System (ADS)

    Wang, Zhicong; Li, Guowen; Li, Genbao; Li, Dunhai

    2012-01-01

    Eutrophication has become a serious concern in many lakes, resulting in cyanobacterial blooms. However, the mechanism and pathways of cyanobacteria decline are less understood. To identify and define the growth and decline of Microcystis blooms in Taihu Lake of China, and to illuminate the destination of surface floating blooms, we investigated the biomass distribution and variations in colony size, morphology, and floating velocity from October 2008 to September 2009. The results showed that the Microcystis bloom declined in response to biomass decrease, colony disaggregation, buoyancy reduction, and increased phytoplankton biodiversity, and these indicative parameters could be applied for recognition of the development phases of the bloom. Three major decline pathways were proposed to describe the bloom decline process, colony disaggregation (Pathway I), colony settlement (Pathway II), and cell lysis in colonies (Pathway III). We proposed a strategy to define the occurrence and decline of Microcystis blooms, to evaluate the survival state under different stress conditions, and to indicate the efficiency of controlling countermeasures against algal blooms.

  2. Seed banks and their implications of rivers with different trophic levels in Chaohu Lake Basin, China.

    PubMed

    Cui, Naxin; Wu, Juan; Zhong, Fei; Yang, Lihua; Xiang, Dongfang; Cheng, Shuiping; Zhou, Qi

    2015-02-01

    The seed banks of three rivers, with different trophic levels in Chaohu Lake Basin, China, were investigated to explore the dynamics of seed bank under the pressure of eutrophication. A total of 60 species from 25 family 43 genera were identified from the seed banks of the three rivers. In the eutrophic Paihe River, the species richness and mean seed density were the highest, followed by the oligotrophic Hangbuhe River and the hypereutrophic Nanfeihe River. Various compositions of three functional group assemblage of hydro-ecotypes were found in different rivers. The dominant and endemic species were aquatic, wetland, and terrestrial species in Hangbuhe River, Paihe River, and Nanfeihe River, respectively. The shift trend of seed bank in three rivers probably presented past vegetation dynamics under the trophic process in the rivers of Chaohu Lake Basin. Seed bank in the river bed might be quickly assessed by its trophic level. Additionally, it might imply that the seed bank with more aquatic species in the oligotrophic river would be a potential seed resource for vegetation restoration of severely degraded river ecosystems.

  3. Movement analysis of free-grazing domestic ducks in Poyang Lake, China: A disease connection

    USGS Publications Warehouse

    Prosser, Diann J.; Palm, Eric C.; Takekawa, John Y.; Zhao, Delong; Xiao, Xiangming; Li, Peng; Liu, Ying; Newman, Scott H.

    2015-01-01

    Previous work suggests domestic poultry are important contributors to the emergence and transmission of highly pathogenic avian influenza throughout Asia. In Poyang Lake, China, domestic duck production cycles are synchronized with arrival and departure of thousands of migratory wild birds in the area. During these periods, high densities of juvenile domestic ducks are in close proximity to migratory wild ducks, increasing the potential for the virus to be transmitted and subsequently disseminated via migration. In this paper, we use GPS dataloggers and dynamic Brownian bridge models to describe movements and habitat use of free-grazing domestic ducks in the Poyang Lake basin and identify specific areas that may have the highest risk of H5N1 transmission between domestic and wild birds. Specifically, we determine relative use by free-grazing domestic ducks of natural wetlands, which are the most heavily used areas by migratory wild ducks, and of rice paddies, which provide habitat for resident wild ducks and lower densities of migratory wild ducks. To our knowledge, this is the first movement study on domestic ducks, and our data show potential for free-grazing domestic ducks from farms located near natural wetlands to come in contact with wild waterfowl, thereby increasing the risk for disease transmission. This study provides an example of the importance of movement ecology studies in understanding dynamics such as disease transmission on a complicated landscape.

  4. Movement analysis of free-grazing domestic ducks in Poyang Lake, China: a disease connection

    PubMed Central

    Prosser, Diann J.; Palm, Eric C.; Takekawa, John. Y; Zhao, Delong; Xiao, Xiangming; Li, Peng; Liu, Ying; Newman, Scott H.

    2016-01-01

    Previous work suggests domestic poultry are important contributors to the emergence and transmission of highly pathogenic avian influenza throughout Asia. In Poyang Lake, China, domestic duck production cycles are synchronized with arrival and departure of thousands of migratory wild birds in the area. During these periods, high densities of juvenile domestic ducks are in close proximity to migratory wild ducks, increasing the potential for the virus to be transmitted and subsequently disseminated via migration. In this paper, we use GPS dataloggers and dynamic Brownian bridge models to describe movements and habitat use of free-grazing domestic ducks in the Poyang Lake basin and identify specific areas that may have the highest risk of H5N1 transmission between domestic and wild birds. Specifically, we determine relative use by free-grazing domestic ducks of natural wetlands, which are the most heavily used areas by migratory wild ducks, and of rice paddies, which provide habitat for resident wild ducks and lower densities of migratory wild ducks. To our knowledge, this is the first movement study on domestic ducks, and our data show potential for free-grazing domestic ducks from farms located near natural wetlands to come in contact with wild waterfowl, thereby increasing the risk for disease transmission. This study provides an example of the importance of movement ecology studies in understanding dynamics such as disease transmission on a complicated landscape. PMID:27695384

  5. Mineral magnetic record of environment in Late Pleistocene and Halocene sediments, Lake Manas, Xinjiang, China

    NASA Astrophysics Data System (ADS)

    Jelinowska, A.; Tucholka, P.; Gasse, F.; Fontes, J. C.

    1995-04-01

    A study of magnetic parameters was carried out on a Late Pleistocene and Holocene sedimentary sequence (5 m) from Lake Manas (northern Xinjiang, China), that has already been analyzed for bulk sediment mineralogy, stables isotopes from carbonates and biogenic material. Magnetic minerals confirm major changes in paleoenvironmental and paleohydrological conditions that were deduced from other methods. They also provide complementary information on changes in the lake system during the early and middle Holocene. The most important mineral magnetic change results from the authigenic formation of ferrimagnetic greigite, Fe3S4 during the lacustrine episodes dated from approximately 8.7 kyr B.P. to approximately 5.5 kyr B.P. (380-335 cm) and from approximately 4.5 kyr B.P. to approximately 3.5 kyr B.P. (320-285 cm) respectively. Our data also indicate an abrupt break in sedimentary conditions which coincides with a short-term return towards dry climatic conditions around 3.5 kyr B.P., which was only suggested from other proxy data.

  6. Landslide susceptibility in the Tully Valley area, Finger Lakes region, New York

    USGS Publications Warehouse

    Jager, Stefan; Wieczorek, Gerald E.

    1994-01-01

    As a consequence of a large landslide in the Tully Valley, Onondaga County, New York, an investigation was undertaken to determine the factors responsible for the landslide in order to develop a model for regional landslide susceptibility. The April 27, 1993 Tully Valley landslide occurred within glacial lake clays overlain by till and colluvium on gentle slopes of 9-12 degrees. The landslide was triggered by extreme climatic events of prolonged heavy rainfall combined with rapid melting of a winter snowpack. A photoinventory and field checking of landslides within a 415 km2 study area, including the Tully Valley, revealed small recently-active landslides and other large dormant prehistoric landslides, probably Pleistocene in age. Similar to the larger Tully Valley landslide, the smaller recently-active landslides occurred in red, glacial lake clays very likely triggered by seasonal rainfall. The large dormant landslides have been stable for long periods as evidenced by slope denudational processes that have modified the landslides. These old and ancient landslides correspond with proglacial lake levels during the Pleistocene, suggesting that either inundation or rapid drainage was responsible for triggering these landslides. A logistic regression analysis was performed within a Geographic Information System (GIS) environment to develop a model of landslide susceptibility for the Tully Valley study area. Presence of glacial clays, slope angle, and glacial lake levels were used as explanatory variables for landslide incidence. The spatial probability of landsliding, categorized as low, moderate and high, is portrayed within 90-m square cells on the susceptibility map.

  7. Paradigms and proboscideans in the southern Great Lakes region, USA

    USGS Publications Warehouse

    Saunders, J.J.; Grimm, E.C.; Widga, C.C.; Campbell, G.D.; Curry, B. Brandon; Grimley, D.A.; Hanson, P.R.; McCullum, J.P.; Oliver, J.S.; Treworgy, J.D.

    2010-01-01

    Thirteen new chronometric dates for Illinois proboscideans are considered in relation to well-dated pollen records from northeastern and central Illinois. These dates span an interval from 21,228 to 12,944 cal BP. When compared to pollen spectra, it is evident that Mammut americanum inhabited spruce (Picea) and black ash (Fraxinus nigra) forest during the B??lling-Aller??d (14,700-12,900 cal BP) and early Younger Dryas (12,900-11,650 cal BP) chronozones. Both Mammuthus jeffersonii and Mammuthus primigenius inhabited spruce dominated open-woodland during the Oldest Dryas chronozone, while M.??primigenius persisted in a forest of predominantly black ash during the Aller??d chronozone. A newly discovered specimen from Lincoln, IL, clarifies the taxonomic distinction between M. primigenius and M.??jeffersonii. Hitherto, a paradigm of proboscidean succession during the full- to late-glacial periods was based on the vegetation succession of steppe tundra-like vegetation to spruce forest to spruce-deciduous forest. The presumed proboscidean succession was that of cold, dry steppe-adapted M. primigenius succeeded by more mesic-tolerant M. jeffersonii that in turn was succeeded by the wet forest-adapted M.??americanum. Reported data do not support this view and indicate a need for re-evaluation of assumptions of proboscidean ecology and history, e.g., the environmental tolerances and habits of M.??primigenius in regions south of 55??N, and its dynamic relationship with other proboscidean taxa. ?? 2009 Elsevier Ltd and INQUA.

  8. Local to regional scale industrial heavy metal pollution recorded in sediments of large freshwater lakes in central Europe (lakes Geneva and Lucerne) over the last centuries.

    PubMed

    Thevenon, Florian; Graham, Neil D; Chiaradia, Massimo; Arpagaus, Philippe; Wildi, Walter; Poté, John

    2011-12-15

    This research first focuses on the spatial and temporal patterns of heavy metals from contrasting environments (highly polluted to deepwater sites) of Lake Geneva. The mercury (Hg) and lead (Pb) records from two deepwater sites show that the heavy metal variations before the industrial period are primarily linked to natural weathering input of trace elements. By opposition, the discharge of industrial treated wastewaters into Vidy Bay of Lake Geneva during the second part of the 20th century, involved the sedimentation of highly metal-contaminated sediments in the area surrounding the WWTP outlet pipe discharge. Eventually, a new Pb isotope record of sediments from Lake Lucerne identifies the long-term increasing anthropogenic lead pollution after ca. 1500, probably due to the development of metallurgical activities during the High Middle Ages. These data furthermore allows to compare the recent anthropogenic sources of water pollution from three of the largest freshwater lakes of Western Europe (lakes Geneva, Lucerne, and Constance). High increases in Pb and Hg highlight the regional impact of industrial pollution after ca. 1750-1850, and the decrease of metal pollution in the 1980s due to the effects of remediation strategies such as the implementation of wastewater treatment plants (WWTPs). However, at all the studied sites, the recent metal concentrations remain higher than pre-industrial levels. Moreover, the local scale pollution data reveal two highly contaminated sites (>100 μg Pb/g dry weight sediment) by industrial activities, during the late-19th and early-20th centuries (Lake Lucerne) and during the second part of the 20th century (Vidy Bay of Lake Geneva). Overall, the regional scale pollution history inferred from the three large and deep perialpine lakes points out at the pollution of water systems by heavy metals during the last two centuries due to the discharge of industrial effluents.

  9. Establishment of Nature Reserves in Administrative Regions of Mainland China

    PubMed Central

    Guo, Ziliang; Cui, Guofa

    2015-01-01

    Nature reserves are widely considered as one available strategy for protecting biodiversity, which is threatened by habitat fragmentation, and wildlife extinction. The Chinese government has established a goal of protecting 15% of its land area by 2015. We quantitated the characteristics and distribution of nature reserves in mainland China and evaluated the expansion process for national nature reserves. National nature reserves occupy 64.15% of the total area of nature reserves. Steppe and meadow ecosystem, ocean and seacoast ecosystem, and wild plant nature reserves represent lower percentages, particularly in national nature reserves, in which they comprised 0.76%, 0.54%, and 0.69%, respectively, of the area. Furthermore, medium and small nature reserves compose 92.32% of all nature reserves. The land area under any legal protection has reached 14.80%, although only 9.78% is strictly protected. However, if 9 super-large national nature reserves, located in Southwest and Northwest China were removed, the percentage of strictly protected area decreases to 2.66% of the land area of China. The areas contained in nature reserves in each province are not proportional to the areas of the provinces, particularly for national nature reserves, with higher protection rates in Southwest and Northwest China than in other regions. Of the 31 provinces, 22 provinces feature strict protection of less than 4% of their areas by national nature reserves; these provinces are mainly located in East, Central, South, and North China. Moreover, the unevenness indexes of the distribution of nature reserves and national nature reserves are 0.39 and 0.58, respectively. The construction of nature reserves has entered a steady development stage after a period of rapid expansion in mainland China. In recent years, the total area of national nature reserves has increased slowly, while the total area of nature reserves has not increased, although the number of nature reserves continues

  10. Application of constructed wetland for urban lake water purification: trial of Xing-qing Lake in Xi'an city, China.

    PubMed

    Cui, F; Zhou, Q; Wang, Y; Zhao, Y Q

    2011-01-01

    A comprehensive review of the current water pollution status in China has indicated that the urban lakes in Chinese cities have suffered from serious pollution and are in high risk of eutrophication, although the pollution sources have been largely controlled. The objective of this study lies in exploring a long term restoration of the aquatic ecosystem in Chinese city lakes using treatment wetland, an environmentally friendly and cost-effective technology. Trials from a subsurface horizontal flow constructed wetland (CW) have demonstrated that the treatment wetland can be used for a purpose such as lake water quality control. Average removal of 84.2% for COD, 53.8% for NH(3)-N, 47.9% for TN, 73.3% for TP and 86.6% for SS can be achieved. Relatively, low removal of nitrogen lies in the lack of nitrification and denitrification process. Accordingly, improved configuration of the treatment wetland system has been proposed and discussed. Finally, the importance of the integrated constructed wetland especially for the application of urban lake water treatment is highlighted.

  11. Ecological risk assessment of ecosystem services in the Taihu Lake Basin of China from 1985 to 2020.

    PubMed

    Xu, Xibao; Yang, Guishan; Tan, Yan; Zhuang, Qianlai; Li, Hengpeng; Wan, Rongrong; Su, Weizhong; Zhang, Jian

    2016-06-01

    There are tremendous theoretical, methodological and policy challenges in evaluating the impact of land-use change on the degradation of ecosystem services (ES) at the regional scale. This study addresses these challenges by developing an interdisciplinary methodology based on the Procedure for Ecological Tiered Assessment of Risk (PETAR). This novel methodology integrates ecological models with a land-use change model. This study quantifies the multi-dimensional degradation risks of ES in the Taihu Lake Basin (TLB) of China from 1985 to 2020. Four key ES related to water purification, water quantity adjustment, carbon sequestration and grain production are selected. The study employs models of Denitrification-Decomposition (DNDC), Soil-Water-Atmosphere-Plant (SWAP), Biome-BGC and Agro-ecological Zoning (AEZ) for assimilations. Land-use changes by 2020 were projected using a geographically weighted multinomial logit-cellular automata (GWML-CA) model. The results show that rapid land-use change has posed a great degradation risk of ES in the region in 1985-2020. Slightly less than two-thirds of the basin experienced degradation of ES over the 1985-2010 period, and about 12% of the basin will continue to experience degradation until 2020. Hot spots with severe deterioration in 2010-2020 are projected to be centered around some small and less developed cities in the region. Regulating accelerated urban sprawl and population growth, reinforcing current environmental programs, and establishing monitoring systems for observing dynamics of regional ES are suggested as practical counter-measures.

  12. [Relationships between urbanization and water resource utilization in Dongting Lake District of South-central China].

    PubMed

    Li, Jing-Zhi; Zhu, Xiang; Li, Jing-Bao; Xu, Mei

    2013-06-01

    By using analytic hierarchy process and entropy method, the evaluation index system and the response relationship model of comprehensive development level of urbanization and comprehensive development and utilization potential of water resources in Dongting Lake District were constructed, with the key affecting factors, their change characteristics, and response characteristics from 2001 to 2010 analyzed. During the study period, the Dongting Lake District was undergoing a rapid development of urbanization, and at a scale expansion stage. The economic and social development level was lagged behind the population and area increase, and the quality and efficiency of urbanization were still needed to be improved. With the advance of urbanization, the water consumption increased yearly, and the water resources utilization efficiency and management level improved steadily. However, the background condition of water resources and their development and utilization level were more affected by hydrological environment rather than urbanization. To a certain extent, the development of urbanization in 2001, 2002, 2005, 2006, 2007, 2009 was slowed down by the shortage of water resources. At present, Dongting Lake region was confronted with the dual task of improving the level and quality of urbanization, and hence, it would be necessary to reform the traditional epitaxial expansion of urbanization and to enhance the water resource support capability.

  13. The Distribution Pattern of Sediment Archaea Community of the Poyang Lake, the Largest Freshwater Lake in China

    PubMed Central

    Ma, Yantian; Liu, Fangpeng; Kong, Zhaoyu; Kou, Wenbo

    2016-01-01

    Archaea plays an important role in the global geobiochemical circulation of various environments. However, much less is known about the ecological role of archaea in freshwater lake sediments. Thus, investigating the structure and diversity of archaea community is vital to understand the metabolic processes in freshwater lake ecosystems. In this study, sediment physicochemical properties were combined with the results from 16S rRNA clone library-sequencing to examine the sediment archaea diversity and the environmental factors driving the sediment archaea community structures. Seven sites were chosen from Poyang Lake, including two sites from the main lake body and five sites from the inflow river estuaries. Our results revealed high diverse archaea community in the sediment of Poyang Lake, including Bathyarchaeota (45.5%), Euryarchaeota (43.1%), Woesearchaeota (3.6%), Pacearchaeota (1.7%), Thaumarchaeota (1.4%), suspended Lokiarchaeota (0.7%), Aigarchaeota (0.2%), and Unclassified Archaea (3.8%). The archaea community compositions differed among sites, and sediment property had considerable influence on archaea community structures and distribution, especially total organic carbon (TOC) and metal lead (Pb) (p < 0.05). This study provides primary profile of sediment archaea distribution in freshwater lakes and helps to deepen our understanding of lake sediment microbes. PMID:28070167

  14. The Distribution Pattern of Sediment Archaea Community of the Poyang Lake, the Largest Freshwater Lake in China.

    PubMed

    Ma, Yantian; Liu, Fangpeng; Kong, Zhaoyu; Yin, Jianhua; Kou, Wenbo; Wu, Lan; Ge, Gang

    2016-01-01

    Archaea plays an important role in the global geobiochemical circulation of various environments. However, much less is known about the ecological role of archaea in freshwater lake sediments. Thus, investigating the structure and diversity of archaea community is vital to understand the metabolic processes in freshwater lake ecosystems. In this study, sediment physicochemical properties were combined with the results from 16S rRNA clone library-sequencing to examine the sediment archaea diversity and the environmental factors driving the sediment archaea community structures. Seven sites were chosen from Poyang Lake, including two sites from the main lake body and five sites from the inflow river estuaries. Our results revealed high diverse archaea community in the sediment of Poyang Lake, including Bathyarchaeota (45.5%), Euryarchaeota (43.1%), Woesearchaeota (3.6%), Pacearchaeota (1.7%), Thaumarchaeota (1.4%), suspended Lokiarchaeota (0.7%), Aigarchaeota (0.2%), and Unclassified Archaea (3.8%). The archaea community compositions differed among sites, and sediment property had considerable influence on archaea community structures and distribution, especially total organic carbon (TOC) and metal lead (Pb) (p < 0.05). This study provides primary profile of sediment archaea distribution in freshwater lakes and helps to deepen our understanding of lake sediment microbes.

  15. Crustal Structure Beneath the Lake Ontario Region from Inverse Models of Potential Field and Seismic Data

    NASA Astrophysics Data System (ADS)

    Navarrete, L. C.; Benoit, M. H.; Ebinger, C. J.; Horowitz, F.

    2014-12-01

    The regions surrounding Lake Ontario (e.g. the Adirondack mountain region and its northern border with Canada) are among the most seismically active regions in the Eastern US. However, only scant knowledge exists of the location and geometry of faults, suture zones, or crustal thickness variations that may localize strain in the crust beneath sections of New York, Pennsylvania and Ontario. Our aim is to determine the crustal density and magnetic susceptibility contrasts (e.g., steep faults, intrusive bodies, Moho topography) which give rise to anomaly patterns and to place constraints on their geometries and locations. With a better understanding of these structures, we will examine how the distribution of the faults and steep contacts throughout the region compare with zones of active seismicity. Utilizing the North American Gravity Database, we created a profile that crosses a narrow Bouguer anomaly with steep gradients surrounded by Bouguer anomaly highs transecting the lake and extending onshore east of Rochester, subparallel to the seismically active Clarendon-Linden fault. Euler deconvolution and 'worm' analyses show that this narrow anomaly is bounded by east-dipping faults that extend to mid-crustal levels. We perform receiver function analyses of Earthscope TA stations in the region in order to constrain crustal thickness and lateral variations in Vp/Vs. These receiver functions at onshore sites in the area show complex Moho structure which partially explains our anomaly.Additionally, a vintage seismic profile coupled with the Lake Ontario bathymetry dataset was used to place constraints on sedimentary strata thicknesses and to identify structures within Proterozoic basement. Predictive models of crustal variations were created from a potential field profile, receiver functions, and a seismic profile to test interpretations. The Moho topography alone does not fully explain the short wavelength gravity anomaly, and a sedimentary basin of 3-5 km in depth is

  16. Climate Change in Africa: Impacts and Effects on the Inhabitants of the Lake Chad Region.

    NASA Astrophysics Data System (ADS)

    Abubakar, B.; Tahir, S. M.; Olisa, O.

    2009-05-01

    The Department of Energy and Climate Change defined climate as the average weather experienced over a long period. This includes temperature, wind and rainfall patterns. The climate of the Earth is not static, and has changed many times in response to a variety of natural causes. Due to human activities in emmiting green house gases has resulted the Earth to get warmed by 0.74°C over the last hundred years. Around 0.4°C of this warming has occurred since the 1970s. Climate is now one of the major phenomenon threatening lives and humanity in general since the beginning of industrial revolution. Climate exerts a profound influence on the lives of poor populations in the Lake Chad region of Africa who depend on fishing and crop cultivation for livelihood and sustenance, who are unprotected against climate-related diseases, who lacked secure access to water and food and who are vulnerable to hydro meteorological hazard. The effects of climate change on the study area are many and include diminishing resources and conflicts over the available limited water resources. The Lake Chad region is a fragile area with high climate variability and extremes of weather. As this inland water is used for domestic and agricultural purposes, salt mining, as well as transportation by Nigerians, Nigeriens, Chadian and Cameroonians, it is an area of trans-boundary water conflicts. This paper examines the part played by climate change in the decline of fishery resources and livelihood activities in the Lake Chad region. Data from field studies, structured interview and secondary sources show that fish catches and livelihood activities have declined tremendously in recent times due to several factors including overexploitation and increasing demands on the aquatic resources. Findings from the study show that droughty periods have resulted in the reduction of open lake water surface from about 25,000 km2 in 1973 to less than 2,000 km2 in the 1990s. This has led to the diminishing aquatic

  17. Spatiotemporal distribution of algal and nutrient, and their correlations based on long-term monitoring data in Lake Taihu, China

    NASA Astrophysics Data System (ADS)

    Acharya, K.; Li, Y.; Stone, M.; Yu, Z.; Young, M.; Shafer, D. S.; Zhu, J.; Warwick, J. J.

    2009-12-01

    Eutrophication in Lake Taihu - China’s third largest freshwater lake - has led to deterioration of water quality and caused more frequent cyanobacteria blooms at many lake locations in recent years. Eutrophication is thought to be fueled by increased nutrient loading, a consequence of rapid population and economic growth in the region. To understand the spatiotemporal distribution of algal blooms, a database was developed that includes long-term meteorological, hydrological, water quality, and socioeconomic data from the Lake Taihu watershed. The data were collected through various field observations, and augmented with information from local and provincial agencies, and universities. Based on the data, spatiotemporal distributions of, and correlations between, chlorophyll-a (Chl-a), total phosphorus (TP), total nitrogen (TN) and water temperature (WT) were analyzed. Results revealed a high degree of correlation between TP and Chl-a concentrations during warm seasons, with high concentrations of both substances present in the northern and northwest portions of the lake. During winter months, Chl-a concentrations were more strongly correlated with WT. Spatial trends in TP and TN concentrations corresponded to observed nutrient fluxes from adjoining rivers in densely populated areas, demonstrating the influence of watershed pollutant loads on lake water quality. Among important questions to be answered is whether wind-driven resuspension of existing nutrients in sediments in this shallow (< 3 m) lake may cause cyanobacteria blooms to begin. This study identifies other questions, data gaps, and research needs, and provides a foundation for improving lake management strategies.

  18. The occurrence and distribution of antibiotics in Lake Chaohu, China: seasonal variation, potential source and risk assessment.

    PubMed

    Tang, Jun; Shi, Taozhong; Wu, Xiangwei; Cao, Haiqun; Li, Xuede; Hua, Rimao; Tang, Feng; Yue, Yongde

    2015-03-01

    The distribution and seasonal variation of fifteen antibiotics belonging to three classes (sulfonamides, fluoroquinolones and tetracyclines) were investigated in Lake Chaohu, China. The concentrations of the selected antibiotics in the surface water, eight major inflowing rivers and sewage treatment plant (STP) samples were analyzed by UPLC-MS/MS. The results indicated that sulfamethoxazole and ofloxacin were the predominant antibiotics, with maximum concentrations of 95.6 and 383.4ngL(-1), respectively, in the river samples. In Lake Chaohu, the western inflowing rivers (the Nanfei and Shiwuli Rivers) were the primary import routes for the antibiotics, and the domestic effluent from four STPs were considered the primary source of the antibiotics. The level of antibiotics in Lake Chaohu clearly varied with seasonal changes, and the highest detectable frequencies and mean concentrations were found during the winter. The quality of water downstream of Lake Chaohu was influenced by the lake, and the results of risk assessment of the antibiotics on aquatic organisms suggested that sulfamethoxazole, ofloxacin, ciprofloxacin and enrofloxacin in the surface water of Lake Chaohu and inflowing rivers might pose a high risk to algae and plants.

  19. Regional and Global Impacts of Megacity Air Pollution in China

    NASA Astrophysics Data System (ADS)

    Zhang, Renyi

    2014-05-01

    Air quality has deteriorated in many megacities of China because of their rapid economic developments. For example, as the world's second largest economy, China has experienced severe air pollution, with aerosols or fine particulate matter less than 2.5 micrometers (PM2.5) reaching unprecedented high levels across many cities in recent winters. In addition to the impacts of aerosols on air chemistry, visibility, and human health, intense aerosol pollution is believed to exert profound impacts on the regional and global atmosphere and climate. In the first part of the talk, perspectives are provided on formation and transformation of haze in China. In the second part the long-term impacts of aerosols on precipitation and lightning over a megacity area in China will be presented, on the basis of atmospheric observations and simulations using a cloud-resolving WRF model. Our results reveal that elevated aerosol loading suppresses light and moderate precipitation, but enhances heavy precipitation. Also, we demonstrate climatically modulated mid-latitude cyclones by Asian pollution over past three decades, using a novel hierarchical modeling approach and observational analysis. Our results unambiguously reveal a large impact of the Asian pollutant outflows on the global general circulation and climate.

  20. Trends in summer chemistry linked to productivity in lakes recovering from acid deposition in the Adirondack region of New York

    USGS Publications Warehouse

    Momen, B.; Lawrence, G.B.; Nierzwicki-Bauer, S. A.; Sutherland, J.W.; Eichler, L.W.; Harrison, J.P.; Boylen, C.W.

    2006-01-01

    The US Environmental Protection Agency established the Adirondack Effects Assessment Program (AEAP) to evaluate and monitor the status of biological communities in lakes in the Adirondack region of New York that have been adversely affected by acid deposition. This program includes chemical analysis of 30 lakes, sampled two to three times each summer. Results of trends analysis for lake chemistry and chlorophyll a (chlor a) are presented for 1994 to 2003, and a general comparison is made with recent results of the Adirondack Long-Term Monitoring (ALTM) Program, which included chemical analysis of all but two of these lakes (plus an additional 24 lakes) monthly, year-round for 1992-2004. Increases in pH were found in 25 of the 30 AEAP lakes (P < 0.05) and increases in acid-neutralizing capacity (ANC) were found in 12 of the 30 lakes (P < 0.05). Concentrations of both SO 42- and Mg 2+ decreased in 11 lakes (P < 0.05), whereas concentrations of NO 3- decreased in 20 lakes (P < 0.05). Concentrations of NH 4+ decreased in 10 lakes at a significance level of P < 0.05 and in three other lakes based on P < 0.1. Concentrations of inorganic and organic monomeric aluminum generally were below the reporting limit of 1.5 ??mol L-1, but decreases were detected in four and five lakes, respectively (P < 0.1). Concentrations of chlor a increased in seven lakes at a significance level of P < 0.05 and two lakes at a significance level of P < 0.1. A significant inverse correlation was also found between chlor a and NO 3- concentrations in nine lakes at a significance level of P < 0.05 and two lakes at a significance level of P < 0.1. Results of AEAP analysis of lake chemistry were similar to those of the ALTM Program, although decreases in SO 42- concentrations were more evident in the year-round ALTM record. Overall, the results suggest (a) a degree of chemical recovery from acidification during the summer, (b) an increase in phytoplankton productivity, and (c) a decreasing trend in

  1. Life cycle GHG emissions of sewage sludge treatment and disposal options in Tai Lake Watershed, China.

    PubMed

    Liu, Beibei; Wei, Qi; Zhang, Bing; Bi, Jun

    2013-03-01

    The treatment and disposal of sewage sludge generate considerable amounts of greenhouse gases (GHGs) and pose environmental and economic challenges to wastewater treatment in China. To achieve a more informed and sustainable sludge management, this study conducts a life cycle inventory to investigate the GHG performances of six scenarios involving various sludge treatment technologies and disposal strategies. These scenarios are landfilling (S1), mono-incineration (S2), co-incineration (S3), brick manufacturing (S4), cement manufacturing (S5), and fertilizer for urban greening (S6). In terms of GHG emissions, S2 demonstrates the best performance with its large offset from sludge incineration energy recovery, followed by S4 and S6, whereas S1 demonstrates the poorest performance primarily because of its large quantity of methane leaks. The scenario rankings are affected by the assumptions of GHG offset calculation. In most scenarios, GHG performance could be improved by using waste gas or steam from existing facilities for drying sludge. Furthermore, considering the GHG performance along with economic, health, and other concerns, S6 is recommended. We thus suggest that local governments promote the use of composted sludge as urban greening fertilizers. In addition, the use of sludge with 60% water content, in place of the current standard of 80%, in wastewater treatment plants is proposed to be the new standard for Tai Lake Watershed in China.

  2. A needs assessment for climate change education in the Great Lakes region

    NASA Astrophysics Data System (ADS)

    Rutherford, S.; Schneider, L. B.; Walters, H.

    2011-12-01

    The National Science Foundation funded Great Lakes Climate Change Science and Education Systemic Network project is implementing a two year planning effort to create innovative education programs to benefit the public, formal and informal educators, scientists, and journalists in the region. The current partners include Eastern Michigan University, NOAA's Great Lakes Environmental Research Lab, University of Michigan, Michig