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Sample records for lake dianchi china

  1. Prevalence of antibody to Toxoplasma gondii in black-headed gulls (Chroicocephalus ridibundus), Dianchi Lake, China.

    PubMed

    Miao, Qiang; Han, Jiang-qiang; Xiang, Xun; Yuan, Fei-Zhou; Liu, Yong-zhang; Duan, Gang; Zhu, Xing-quan; Zou, Feng-cai

    2014-07-01

    Sera from 659 Black-headed Gulls (Chroicocephalus ridibundus) in Dianchi Lake, China were assayed for Toxoplasma gondii antibodies using the modified agglutination test (MAT). Specific T. gondii antibodies were detected in 131 (19.9%) Black-headed Gulls (MAT titer ≥ 1 ∶ 5). These results indicate that T. gondii infection is common in Black-headed Gulls.

  2. 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

  3. 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

  4. Estimating net anthropogenic nitrogen inputs (NANI) in the Lake Dianchi basin of China

    NASA Astrophysics Data System (ADS)

    Gao, W.; Howarth, R. W.; Hong, B.; Swaney, D. P.; Guo, H. C.

    2014-08-01

    Net anthropogenic nitrogen inputs (NANI) with components of atmospheric N deposition, synthetic N fertilizer, agricultural N fixation and N in net food and feed imports from 15 catchments in the Lake Dianchi basin were determined over an 11-year period (2000-2010). The 15 catchments range in size from 44 km2 to 316 km2 with an average of 175 km2. To reduce uncertainty from scale change methodology, results from data extraction by area-weighting and land use-weighting methods were compared. Results show that the methodology for extrapolating data from the county scale to watersheds has a great influence on NANI computation for catchments in the Lake Dianchi basin, and that estimates of NANI between the two methods have an average difference of 30% on a catchment basis, while a smaller difference (15%) was observed on the whole Lake Dianchi basin basis. The riverine N export has a stronger linear relationship with NANI computed by the land use-weighting method, which we believe is more reliable. Overall, nitrogen inputs assessed by the NANI approach for the Lake Dianchi basin are 9900 kg N km-2 yr-1, ranging from 6600 to 28 000 kg N km-2 yr-1 among the 15 catchments. Synthetic N fertilizer is the largest component of NANI in most subwatersheds. On average, riverine flux of nitrogen in catchments of the Lake Dianchi basin averages 83% of NANI, far higher than generally observed in North America and Europe. Saturated N sinks and a limited capacity for denitrification in rivers may be responsible for this high percentage of riverine N export. Overall, the NANI methodology should be applicable in small watersheds when sufficiently detailed data are available to estimate its components.

  5. Estimating net anthropogenic nitrogen inputs (NANI) in the Lake Dianchi Basin of China

    NASA Astrophysics Data System (ADS)

    Gao, W.; Howarth, R. W.; Hong, B.; Swaney, D. P.; Guo, H. C.

    2014-03-01

    Net anthropogenic nitrogen inputs (NANI) with components of atmospheric N deposition, synthetic N fertilizer, agricultural N fixation and N in net food and feed imports from 15 catchments in Lake Dianchi Basin were determined over an 11 year period (2000-2010). The 15 catchments range in size from 44 km2 to 316 km2 with an average of 175 km2. To reduce uncertainty from scale change methodology, results from data extracting by area-weighting and land use-weighting methods were compared. Results show that methodology for extrapolating data from county scale to watersheds has a great influence on NANI computation for catchments in the Lake Dianchi Basin, and estimates of NANI between two methods have an average difference of 30% on catchments basis while a smaller difference (15%) was observed on the whole Lake Dianchi Basin basis. The riverine N export has stronger linear relationship with NANI computed by land use-weighting method, which we believe is more reliable. Overall, nitrogen inputs assessed by the NANI approach for the Lake Dianchi Basin are 9900 kg N km-2 yr-1, ranging from 6600 to 28 000 kg N km-2 yr-1 among the 15 catchments. Synthetic N fertilizer is the largest component of NANI in most subwatersheds. On average, riverine flux of nitrogen in catchments of the Lake Dianchi Basin averages 83% of NANI, far higher than generally observed in North America and Europe. Saturated N sinks and limited capacity for denitrification in rivers may be responsible for this high percent of riverine N export. A negative intercept observed in the linear relationship between NANI and riverine N export suggests the influence of pollution control measures on N flux in small watershed. The NANI methodology should be applicable in small watersheds when sufficiently detailed data are available to estimate its components.

  6. 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.

  7. Estimation of nitrogen and phosphorus flows in livestock production in Dianchi Lake basin, China.

    PubMed

    Anzai, Hiroki; Wang, Lin; Oishi, Kazato; Irbis, Chagan; Li, Kunzhi; Kumagai, Hajime; Inamura, Tatsuya; Hirooka, Hiroyuki

    2016-01-01

    We assessed the nitrogen (N) and phosphorus (P) flows in intensified livestock production systems by investigating nutrient budgets and cycling in the basin of Dianchi Lake, one of the most eutrophic lakes in China. We conducted field surveys based on feed samplings and interviews of livestock farmers. The N and P in local and external feeds, animal body retentions, animal products and excretions were calculated at the individual level for dairy cattle, fattening pigs, breeding sows, broilers and laying hens. The N and P flows in the total livestock production system in the area were estimated by multiplying the individual N and P budgets by the number of animals. For the dairy and fattening pig productions, N and P supplied from local crops or by-products accounted for large parts of the inputs. For the other livestock categories, most of the N and P inputs depended on external resources. The N and P outputs through animal manure into the cropland were 287 and 66 kg/ha/year, respectively, which were higher than the N and P inputs into the livestock production systems from the cropland. The N and P loads from manure should be reduced for the establishment of sustainable agricultural production systems. © 2015 Japanese Society of Animal Science.

  8. 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.

  9. Ecological dynamics of toxic Microcystis spp. and microcystin-degrading bacteria in Dianchi Lake, China.

    PubMed

    Zhu, Lin; Wu, Yanlong; Song, Lirong; Gan, Nanqin

    2014-03-01

    Toxic cyanobacterial blooms directly threaten both human safety and the ecosystem of surface waters. The widespread occurrence of these organisms, coupled with the tumor-promoting properties of the microcystin toxins that they produce, demands action to mitigate their potential impacts and, thus, a robust understanding of their ecological dynamics. In the present work, the abundance of toxic Microcystis spp. and microcystin (MC)-degrading bacteria in Dianchi Lake, located in Yunnan Province, China, was studied using quantitative PCR. Samples were taken at monthly intervals from June 2010 to December 2011 at three sampling stations within this freshwater lake. Results revealed that variation in the abundance of both total Microcystis spp. and toxic Microcystis spp. exhibited similar trends during the period of the algal bloom, including the reinvasion, pelagic growth, sedimentation, and overwintering periods, and that the proportion of toxic Microcystis was highest during the bloom and lowest in winter. Importantly, we observed that peaks in mlrA gene copy numbers of MC-degrading bacteria occurred in the months following observed peaks in MC concentrations. To understand this phenomenon, we added MCs to the MC-degrading bacteria (designated strains HW and SW in this study) and found that MCs significantly enhanced mlrA gene copy numbers over the number for the control by a factor of 5.2 for the microcystin-RR treatment and a factor of 3.7 for the microcystin-LR treatment. These results indicate that toxic Microcystis and MC-degrading bacteria exert both direct and indirect effects on each other and that MC-degrading bacteria also mediate a shift from toxic to nontoxic populations of Microcystis.

  10. [Retrieve phycocyanin concentrations based on semi-analytical model in the Dianchi Lake, China].

    PubMed

    Yin, Bin; Lü, Heng; Li, Yun-Mei; Wu, Chuan-Qing; Zhu, Li; Wang, Yan-Fei

    2011-02-01

    Phycocyanin (PC) in the blue-green algae is usually used to detective the quantity of the blue-green algae, because of its special absorption at band 620 nm. A semi-analytical model retrieving phycocyanin concentrations is been built, based on a nested semi-empirical band ratio algorithm, using the data sets collected in September 19 and September 20, 2009 from Dianchi Lake. The empirical relationship between the specific absorption coefficient at band 620 nm [a(PC)* (620)] and the absorption coefficient at band 620 nm [a(PC) (620)] reduces the impact of the variability of a(PC)* (620) in the model built by Simis. The new semi-analytical model is proved well done in retrieving phycocyanin concentrations and has a mean relative error (MRE) 21.63% by the dataset collected on December 1, 2009 from Dianchi Lake. The model error analysis prove that the main reason of the error is caused by the component and concentrations of pigments changing seasonally in the blue-green algae.

  11. Satellite data regarding the eutrophication response to human activities in the plateau lake Dianchi in China from 1974 to 2009.

    PubMed

    Huang, Changchun; Wang, Xiaolei; Yang, Hao; Li, Yunmei; Wang, Yanhua; Chen, Xia; Xu, Liangjiang

    2014-07-01

    Human activities contribute highly to water eutrophication. In this study, the relationship between human activities and water eutrophication in Dianchi Lake in China was characterized using a combination of satellite imaging, sedimentary physicochemical and meteorological data analyses. The heavy eutrophic status and algal bloom in Dianchi Lake were first observed by satellite in 1977 and 1989, respectively. The C/N ratio, an indicator of organic sources in sediments, also showed that the planktonic organic source in the sediment significantly increased beginning in 1989. The land use cover in the Dianchi basin showed that both farm lands and forests, but particularly farmlands, were reduced during the period from 1974 to 2009. The urbanized land area increased from 1974 to 2009, particularly after 2000. The effects of human activities on water eutrophication were expressed by land use cover, population, gross domestic product (GDP; separated into primary, secondary and tertiary industries) and wastewater discharge. For land use cover, farm and urbanized lands were the main sources of water nutrients; forest contributed slightly to these nutrients. For GDP, primary (correlation coefficient=0.94, P<0.001) and tertiary (correlation coefficient=0.95, P<0.001) industries were highly correlated with total nitrogen. Secondary (correlation coefficient=0.95, P<0.001) and tertiary (correlation coefficient=0.96, P<0.001) industries were highly correlated with total phosphorus. The algal bloom area was significantly correlated with wastewater discharge (correlation coefficient=0.78, P<0.005) (except industrial wastewater), which was primarily led by the non-agricultural population, from 2000 to 2009. This study suggests that the protection of water environments requires a comprehensive protection policy in addition to a unilateral protection policy. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. 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

  13. Seasonal distribution, source investigation and vertical profile of phenolic endocrine disrupting compounds in Dianchi Lake, China.

    PubMed

    Wang, Bin; Huang, Bin; Jin, Wei; Wang, Yu; Zhao, Shimin; Li, Farong; Hu, Ping; Pan, Xuejun

    2012-04-01

    Phenolic endocrine disrupting compounds, including nonylphenol-di-ethoxylate (NP2EO), nonylphenol-mono-ethoxylate (NP1EO), 4-nonylphenol (4-NP), bisphenol A (BPA), 4-cumylphenol (4-CP) and 4-tert-octylphenol (4-t-OP), were investigated in water, surface sediment and sediment cores in Dianchi Lake to track their seasonal distributions, pollution sources and historical trends. The concentrations of NP2EO, NP1EO, 4-NP, BPA, 4-CP and 4-t-OP were up to 295.14, 448.48, 45.28, 530.33, 8.96 and 21.37 ng L(-1) in water, and up to 297.11, 809.63, 4.58, 166.87, 3.62 and 40.69 ng g(-1) dry weight in surface sediment, respectively. Except BPA in water, concentrations of all the other phenolic compounds in both of the matrices were higher in January than in July, 2011. The concentrations decreased significantly with an increase in distance from the sampling locations which were adjacent to the urban areas (Kunming City, Chenggong City and Jinning City). The pollution of phenolic EDCs came mainly from industry, agriculture and daily life. The relationships between the concentrations of target compounds and the six water quality parameters were evaluated. There were significant positive correlations between concentrations of phenolic compounds in water and in surface sediment. For sediment cores, three clearly separated maxima occurred in segments 0-5 cm (the late 2000s), 5-10 cm (the early and mid of 2000s) and 20-25 cm (the mid of 1980s), respectively. NP2EO, NP1EO and BPA were the three dominant compounds in the lake.

  14. Occurrence, distribution, and sources of six phenolic endocrine disrupting chemicals in the 22 river estuaries around Dianchi Lake in China.

    PubMed

    Wang, Bin; Huang, Bin; Jin, Wei; Zhao, Shimin; Li, Farong; Hu, Ping; Pan, Xuejun

    2013-05-01

    The objectives of this study are to track the occurrence, distribution, and sources of phenolic endocrine disrupting compounds (EDCs) in the 22 rivers around Dianchi Lake in China, to estimate the input and output amounts of phenolic EDCs in the water system, and to provide more comprehensive fundamental data for risk assessment and contamination control of phenolic EDCs in aquatic environment. Six phenolic EDCs were systematically evaluated in water and surface sediment in the estuaries of those rivers. The water and sediment samples were preconcentrated by solid-phase extraction system and microwave-assisted extraction system, respectively. Phenolic EDCs were analyzed by GC-MS (Thermo Fisher Scientific, USA) after derivatization. Phenolic EDCs were found ubiquitously in the aquatic environment. The total concentrations ranged from 248 to 4,650 ng/L in water, and 113 to 3,576 ng/g dry weight in surface sediment. The residue amount of phenolic EDCs in Dianchi Lake was 258 kg/a. Concentrations of the phenolic EDCs in the Lake decreased with increase in distance to the estuaries of those rivers which run through urban and industrial areas. The rivers seriously contaminated by phenolic EDCs were Xin River, Yunliang River, Chuanfang River, Cailian River, Jinjia River, Zhengda River, and Daqing River which run through the old area of Kunming City. Satisfying correlations were observed between the concentrations of the target compounds in water and in surface sediment. NP1EO, NP2EO, and BPA were identified as the three predominant phenolic EDCs. There were significant correlations between phenolic EDCs and many basic water quality parameters. Urban and industrial areas are the major contributors for phenolic EDCs, especially in Kunming City. Compositional profiles of phenolic EDCs in surface sediment were similar to those in river water. The concentrations of phenolic EDCs in the rivers located in the northwest part of the valley were very high, and posed a potential

  15. First report of aphantoxins in China--waterblooms of toxigenic Aphanizomenon flos-aquae in Lake Dianchi.

    PubMed

    Liu, Yongmei; Chen, Wei; Li, Dunhai; Shen, Yinwu; Li, Genbao; Liu, Yongding

    2006-09-01

    The oligohaline cyanobacterium Aphanizomenon flos-aquae (L.) Ralfs (A. flos-aquae) has been reported in several countries to produce paralytic shellfish poisons (PSPs) or protracted toxic effects. In the past years, A. flos-aquae blooms have occurred annually in the eutrophic Lake Dianchi (300 km(2) in area, located in southwestern China). Material from natural blooms dominated by A. flos-aquae was collected and lyophilized. Acute toxicity testing was performed by mouse bioassay using extracts from the lyophilized material. Clear symptoms of PSPs intoxications were observed. To confirm the production of PSPs, a strain of A. flos-aquae (DC-1) was isolated and maintained in culture. Histopathological effects were studied by examining the organ damages using transmission electron microscopy (TEM). Slight hepatocytic damage with swollen mitochondria was found. The ultrastructural pulmonary lesions were characterized by distortied nuclei and indenting of karyotheca, together with degeneration and tumefaction of mitochondria and endoplasmic reticulum. Control animals injected with acetic acid did not exhibit histopathological damage in any organ. Toxic effects of cultured algal cells on enzymatic systems in the mouse were studied using sublethal doses of extracts. Significant glutathione-S-transferase (GST) and lactate dehydrogenase (LDH) increases, together with decrease of the glutathione (GSH) level, were measured. These results indicated a potential role of PSPs intoxicating and metabolizing in the test animals. HPLC-FLD and LC/MS analysis of extracts from cultured material demonstrated the PSP toxins produced by A. flos-aquae bloom. To the best of our knowledge, this is the first study reporting chemically and toxicologically confirmed PSP toxins related to A. flos-aquae in China.

  16. Six-decade temporal change and seasonal decomposition of climate variables in Lake Dianchi watershed (China): stable trend or abrupt shift?

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Liang, Zhongyao; Liu, Yong; Guo, Huaicheng; He, Dan; Zhao, Lei

    2015-01-01

    Meteorological trend analysis is a useful tool for understanding climate change and can provide useful information on the possibility of future change. Lake Dianchi is the sixth largest freshwater body in China with serious eutrophication. Algal blooms outbreak was proven to be closely associated with some climatic factors in Lake Dianchi. It is therefore essential to explore the trends of climatic time series to understand the mechanism of climate change on lake eutrophication. We proposed an integrated method of Mann-Kendall (MK) test, seasonal-trend decomposition using locally weighted regression (LOESS) (STL), and regime shift index (RSI) to decompose the trend analysis and identify the stable and abrupt changes of some climate variables from 1951 to 2009. The variables include mean air temperature (Tm), maximum air temperatures (Tmax), minimum air temperatures (Tmin), precipitation (Prec), average relative humidity (Hum), and average wind speed (Wind). The results showed that (a) annual Tm, Tmax, and Tmin have a significant increasing trend with the increasing rates of 0.26, 0.15and 0.43 °C per decade, respectively; (b) annual precipitation has an insignificant decreasing trend with the decreasing rate of 3.17 mm per decade; (c) annual Hum has a significant decreasing trend in all seasons; and (d) there are two turning points for temperature rise around 1980 and 1995 and two abrupt change periods for precipitation with the extreme points appearing in 1963 and 1976. Temperature rise and precipitation decline in summer and autumn as well as wind speed decrease after the 1990s may be an important reason for algal blooms outbreak in Lake Dianchi. This study was expected to provide foundation and reference for regional water resource management.

  17. Large-scale utilization of water hyacinth for nutrient removal in Lake Dianchi in China: the effects on the water quality, macrozoobenthos and zooplankton.

    PubMed

    Wang, Zhi; Zhang, Zhiyong; Zhang, Junqian; Zhang, Yingying; Liu, Haiqing; Yan, Shaohua

    2012-11-01

    An ecological engineering project using water hyacinth for nutrient removal was performed in Baishan Bay of a large shallow eutrophic lake, Lake Dianchi in China. In the present study, a systematic survey of water quality, macrozoobenthos and zooplankton inside (IWH), around (AWH) and far away (FWH) water hyacinth mats was conducted in Baishan Bay from August to October 2010. The results showed that the water quality significantly improved at AWH area. Concentrations of nitrogen and phosphorus were lower and transparency was higher at AWH area than those in IWH and FWH areas. Total densities, dominant species densities, and biodiversity indexes of macrozoobenthos and cladocerans as well as copepods did not differ (P>0.05) among each other in all three areas. It was significantly (P<0.05) different for those of rotifers at IWH area compared to those in AWH and FWH areas. The results might suggest a tremendous potential for the utilization of water hyacinth in the eutrophic lake like Lake Dianchi for nutrients removal. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Ecosystem services of human-dominated watersheds and land use influences: a case study from the Dianchi Lake watershed in China.

    PubMed

    Hou, Ying; Li, Bo; Müller, Felix; Chen, Weiping

    2016-11-01

    Watersheds provide multiple ecosystem services. Ecosystem service assessment is a promising approach to investigate human-environment interaction at the watershed scale. The spatial characteristics of ecosystem services are closely related to land use statuses in human-dominated watersheds. This study aims to investigate the effects of land use on the spatial variations of ecosystem services at the Dianchi Lake watershed in Southwest China. We investigated the spatial variations of six ecosystem services-food supply, net primary productivity (NPP), habitat quality, evapotranspiration, water yield, and nitrogen retention. These services were selected based on their significance at the Dianchi Lake watershed and the availability of their data. The quantification of these services was based on modeling, value transference, and spatial analysis in combination with biophysical and socioeconomic data. Furthermore, we calculated the values of ecosystem services provided by different land use types and quantified the correlations between ecosystem service values and land use area proportions. The results show considerable spatial variations in the six ecosystem services associated with land use influences in the Dianchi Lake watershed. The cropland and forest land use types had predominantly positive influences on food productivity and NPP, respectively. The rural residential area and forest land use types reduced and enhanced habitat quality, respectively; these influences were identical to those of evapotranspiration. Urban area and rural residential area exerted significantly positive influences on water yield. In contrast, water yield was negatively correlated with forest area proportion. Finally, cropland and forest had significantly positive and negative influences, respectively, on nitrogen retention. Our study emphasizes the importance of consideration of the influences from land use composition and distribution on ecosystem services for managing the ecosystems of

  19. Occurrence, removal, and fate of progestogens, androgens, estrogens, and phenols in six sewage treatment plants around Dianchi Lake in China.

    PubMed

    Huang, Bin; Li, Xiaoman; Sun, Wenwen; Ren, Dong; Li, Xiao; Li, Xiaonan; Liu, Ying; Li, Qiang; Pan, Xuejun

    2014-11-01

    The occurrence and behavior of endocrine disrupting chemicals (EDCs) in sewage treatment plants (STPs), especially estrogens and phenols, have been closely concerned in previous studies. However, the systematical researches about progestogens and androgens were scarce in STPs adopting different treatment technologies. This work investigated the occurrence, removal, and fate of one progestogen, three androgens, four estrogens, and six phenols in six STPs around Dianchi Lake in China, where the influents, effluents of primary treatment, secondary treatment, and advanced treatment, as well as excess sludge samples, were analyzed. All of the above EDCs were detected out in influents of the six STPs. Bisphenol A, nonylphenol-mono-ethoxylate, and nonylphenol-diethoxylate were the dominant EDCs detected in those influent samples with the concentrations that varied from 637.6 to 1,684.0 ng/L, 633.8 to 1,540.0 ng/L, and 648.7 to 2,246.0 ng/L, respectively; E1 and dihydrotestosterone were the major steroids with the mean concentration of 126.8 and 277.4 ng/L. For effluents and sludges, phenols showed higher concentration (366.8-1,233.0 ng/L and 1,478.1-6,948.9 ng/g dry weight (dw)) and detection rate (100 %). The total removal rates were more than 80 % for most compounds in wastewater treatment processes, and high removal efficiency (86-100 %) was found for androgens and progestogens compared with estrogens (75-92 %) and phenols (62-85 %). The secondary treatment processes play significant roles on degrading EDCs, whereas the primary sedimentation has little effects. The treatment capacity of anoxic-anaerobic-anoxic membrane bioreactor and anaerobic/anoxic/oxic technologies was superior to the conventional oxidation ditch in the degradation of EDCs. The advanced treatment process, two units of filter (D-type or V-type), and ultraviolet disinfection were adopted and presented effective to remove these compounds. According to fate analysis, it was obvious that biological

  20. Spatial-seasonal variation of soil denitrification under three riparian vegetation types around the Dianchi Lake in Yunnan, China.

    PubMed

    Wang, Shaojun; Cao, Zilin; Li, Xiaoying; Liao, Zhouyu; Hu, Binghui; Ni, Jie; Ruan, Honghua

    2013-05-01

    Outbreaks of nuisance cyanobacterial bloom are predicted to occur frequently under the effect of severe eutrophication in the water body of Lake Dianchi since the 1990s. Riparian buffers are now well recognized for their roles in the removal of inorganic nitrogen mainly via denitrification. Little is known, however, about the mechanisms of nitrate removal in the riparian buffers of Lake Dianchi. We investigated the wet and dry seasonal dynamics of denitrification rate (DNR) in the soil profiles along the topographic gradient in three riparian buffers with different vegetation types (i.e. forest, open forest, and grass). A strong vertical pattern was observed in soil organic C and N concentrations (i.e. total N, DON, NO3-N, and NH4-N) along the soil layers. We also found significantly higher in situ denitrification activity in the upper horizon along each topohydrosequence while the activities of soil denitrification could be detected down to deeper soil horizons (0.1 to 0.8 mg N per kg dry soil per day), which may contribute significantly to the reduction of the ground water nitrate. Meanwhile, the DNR in the zones near the lake was significantly higher than that in zones near the border with the upland terrace, and also in the wet seasons than in dry seasons. Denitrification rates in the forest, open forest and grass sites were significantly different only in wet seasons. Especially, we found soil organic C had a strong correlation with denitrification in all sites, despite the large intersite variability of soil and vegetation. Our data suggested spatial heterogeneity of substrate availability along a hydrologic and topographic gradient can be the primary control on spatial-seasonal patterns of denitrification in riparian buffers.

  1. 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

  2. Examining land-use/land-cover change in the Lake Dianchi watershed of the Yunnan-Guizhou Plateau of Southwest China with remote sensing and GIS techniques: 1974–2008.

    PubMed

    Zhao, Yaolong; Zhang, Ke; Fu, Yingchun; Zhang, Hong

    2012-10-24

    Monitoring land-use/land-cover change (LULCC) and exploring its mechanisms are important processes in the environmental management of a lake watershed. The purpose of this study was to examine the spatiotemporal pattern of LULCC by using multi landscape metrics in the Lake Dianchi watershed, which is located in the Yunnan-Guizhou Plateau of Southwest China. Landsat images from the years 1974, 1988, 1998, and 2008 were analyzed using geographical information system (GIS) techniques. The results reveal that land-use/land-cover has changed greatly in the watershed since 1974. This change in land use structure was embodied in the rapid increase of developed areas with a relative change rate of up to 324.4%. The increase in developed areas mainly occurred in agricultural land, especially near the shores of Lake Dianchi. The spatial pattern and structure of the change was influenced by the urban sprawl of the city of Kunming. The urban sprawl took on the typical expansion mode of cyclic structures and a jigsaw pattern and expanded to the shore of Lake Dianchi. Agricultural land changed little with respect to the structure but changed greatly in the spatial pattern. The landscape in the watershed showed a trend of fragmentation with a complex boundary. The dynamics of land-use/land-cover in the watershed correlate with land-use policies and economic development in China.

  3. Examining Land-Use/Land-Cover Change in the Lake Dianchi Watershed of the Yunnan-Guizhou Plateau of Southwest China with Remote Sensing and GIS Techniques: 1974-2008

    PubMed Central

    Zhao, Yaolong; Zhang, Ke; Fu, Yingchun; Zhang, Hong

    2012-01-01

    Monitoring land-use/land-cover change (LULCC) and exploring its mechanisms are important processes in the environmental management of a lake watershed. The purpose of this study was to examine the spatiotemporal pattern of LULCC by using multi landscape metrics in the Lake Dianchi watershed, which is located in the Yunnan-Guizhou Plateau of Southwest China. Landsat images from the years 1974, 1988, 1998, and 2008 were analyzed using geographical information system (GIS) techniques. The results reveal that land-use/land-cover has changed greatly in the watershed since 1974. This change in land use structure was embodied in the rapid increase of developed areas with a relative change rate of up to 324.4%. The increase in developed areas mainly occurred in agricultural land, especially near the shores of Lake Dianchi. The spatial pattern and structure of the change was influenced by the urban sprawl of the city of Kunming. The urban sprawl took on the typical expansion mode of cyclic structures and a jigsaw pattern and expanded to the shore of Lake Dianchi. Agricultural land changed little with respect to the structure but changed greatly in the spatial pattern. The landscape in the watershed showed a trend of fragmentation with a complex boundary. The dynamics of land-use/land-cover in the watershed correlate with land-use policies and economic development in China. PMID:23202820

  4. Effects of engineered application of Eichhornia crassipes on the benthic macroinvertebrate diversity in Lake Dianchi, an ultra-eutrophic lake in China.

    PubMed

    Zhang, Zhiyong; Wang, Zhi; Zhang, Zhenghua; Zhang, Junqian; Guo, Junyao; Li, Enhua; Wang, Xuelei; Liu, Haiqin; Yan, Shaohua

    2016-05-01

    An ecological engineering project with confined growth of 1.5 km(2) of Eichhornia crassipes was implemented to remove pollutants in Lake Dianchi. To assess the ecological effects of this project on benthic macroinvertebrate assemblages, a 1-year investigation at the areas inside and outside E. crassipes mats was conducted from May 2013 to May 2014. All the 10 sampling sites in the areas were grouped into two statistically significant clusters mainly corresponding to inside and outside E. crassipes mat areas (EMAs), by clustering analysis. E. crassipes reduced the densities of pollution indicator taxa (e.g., Oligochaeta and Chironomidae larvae); thus, the total densities of benthic macroinvertebrates at the area inside EMAs (mean 328.2 ind./m(2)) were slightly lower than that at the area outside EMAs (mean 505.6 ind./m(2)). Four functional feeding groups including 38 species of benthic macroinvertebrates were collected at the area inside EMAs, while only three functional feeding groups containing 17 species were collected at the area outside EMAs. The biodiversity indices (Shannon-Weiner, Margalef, Simpson, and Peilou indices) and K-dominance curves also showed higher diversity of benthic macroinvertebrates at the area inside EMAs than at the area outside EMAs. These results suggested that a certain scale of engineering application of E. crassipes was beneficial to benthic macroinvertebrate communities in the ultra-eutrophic Lake Dianchi and it could be used as a pioneer species in ultra-eutrophic lake for pollutant removal.

  5. Response of Spatial Patterns of Denitrifying Bacteria Communities to Water Properties in the Stream Inlets at Dianchi Lake, China

    PubMed Central

    Yi, Neng; Gao, Yan; Zhang, Zhenhua; Wang, Yan; Liu, Xinhong; Zhang, Li; Yan, Shaohua

    2015-01-01

    Streams are an important sink for anthropogenic N owing to their hydrological connections with terrestrial systems, but main factors influencing the community structure and abundance of denitrifiers in stream water remain unclear. To elucidate the potential impact of varying water properties of different streams on denitrifiers, the abundance and community of three denitrifying genes coding for nitrite (nirK, nirS) and nitrous oxide (nosZ) reductase were investigated in 11 streams inlets at the north part of Dianchi Lake. The DGGE results showed the significant pairwise differences in community structure of nirK, nirS, and nosZ genes among different streams. The results of redundancy analysis (RDA) confirmed that nitrogen and phosphorus concentrations, pH, and temperature in waters were the main environmental factors leading to a significant alteration in the community structure of denitrifiers among different streams. The denitrifying community size was assessed by quantitative PCR (qPCR) of the nirS, nirK, and nosZ genes. The abundance of nirK, nirS, and nosZ was positively associated with concentrations of total N (TN) and PO43− (p < 0.001). The difference in spatial patterns between nirK and nirS community diversity, in combination with the spatial distribution of the nirS/nirK ratio, indicated the occurrence of habitat selection for these two types of denitrifiers in the different streams. The results indicated that the varying of N species and PO43− together with pH and temperature would be the main factors shaping the community structure of denitrifiers. Meanwhile, the levels of N in water, together with PO43−, tend to affect the abundance of denitrifiers. PMID:26504771

  6. [Characteristics of nitrogen pollution and the potential mineralization in surface sediments of Dianchi Lake].

    PubMed

    Meng, Ya-Yuan; Wang, Sheng-Rui; Jiao, Li-Xin; Liu, Wen-Bin; Xiao, Yan-Bo; Zu, Wei-Mei; Xu, Tian-Min; Ding, Shuai; Zhou, Tong

    2015-02-01

    The nitrogen content, its different forms and their spatial distribution were studied by using the 53 sediment samples from different sites in Dianchi Lake. Thereafter, the potential nitrogen mineralization ability of the sediments and their pollution characteristics were also explored to understand the influencing factors of nitrogen pollution and its release risk from the sediment surface to the overlying water of Dianchi. The results showed: (1) the average total nitrogen content of surface sediment in Dianchi Lake was 3 515. 60 mg x kg(-1), which was at a high level from the inlets in Caohai Northeast thinning digging area, Panlong River and the Haikou into Dianchi Lake, but relatively low in Baoxiang River Estuary dredging area. The total organic nitrogen (TON) content, accounting for 85.86% of TN, was at a high level; on the other hand, the dissolved inorganic nitrogen ( DIN) content was lower, which accounted for 14.10% of TN. The spatial distribution of TON and TN kept the same trend, but not the DIN. Compared with other Lakes of China, the nitrogen content of sediment in Dianci was at a high level, and the extent of pollution was just below the serious polluted City Lakes. (2) The average potential mineralizable nitrogen (PMN) content of Lake Dianchi was 1 154.76 mg x kg(-1), accounting for 32.90% of TN, which raised the potential risk of its release into the overlying water. Higher PMN was found in the Caohai Lake area and the inlet of Panlong River in the North, the inlet of Luolong Rive in the Middle Lake, the inlet of Baiyukou Lake and Liangwang River in the South. Nowadays, the pH value of Dianchi Lake was favorable for its sediment nitrogen mineralization, and its nitrogen mineralization was affected by the release of NH4(+) -N from organic matter. In the heavy polluted area, the concentration of the overlying water nitrogen was seriously affected by nitrogen mineralization of sediment from Dianchi, while the light polluted area was less affected.

  7. Contrasting patterns of free-living bacterioplankton diversity in macrophyte-dominated versus phytoplankton blooming regimes in Dianchi Lake, a shallow lake in China

    NASA Astrophysics Data System (ADS)

    Wang, Yujing; Li, Huabing; Xing, Peng; Wu, Qinglong

    2017-03-01

    Freshwater shallow lakes typically exhibit two alternative stable states under certain nutrient loadings: macrophyte-dominated and phytoplankton-dominated water regimes. An ecosystem regime shift from macrophytes to phytoplankton blooming typically reduces the number of species of invertebrates and fishes and results in the homogenization of communities in freshwater lakes. We investigated how microbial biodiversity has responded to a shift of the ecosystem regime in Dianchi Lake, which was previously fully covered with submerged macrophytes but currently harbors both ecological states. We observed marked divergence in the diversity and community composition of bacterioplankton between the two regimes. Although species richness, estimated as the number of operational taxonomic units and phylogenetic diversity (PD), was higher in the phytoplankton dominated ecosystem after this shift, the dissimilarity of bacterioplankton community across space decreased. This decrease in beta diversity was accompanied by loss of planktonic bacteria unique to the macrophyte-dominated ecosystem. Mantel tests between bacterioplankton community distances and Euclidian distance of environmental parameters indicated that this reduced bacterial community differentiation primarily reflected the loss of environmental niches, particularly in the macrophyte regime. The loss of this small-scale heterogeneity in bacterial communities should be considered when assessing long-term biodiversity changes in response to ecosystem regime conversions in freshwater lakes.

  8. Contrasting patterns of free-living bacterioplankton diversity in macrophyte-dominated versus phytoplankton blooming regimes in Dianchi Lake, a shallow lake in China

    NASA Astrophysics Data System (ADS)

    Wang, Yujing; Li, Huabing; Xing, Peng; Wu, Qinglong

    2016-04-01

    Freshwater shallow lakes typically exhibit two alternative stable states under certain nutrient loadings: macrophyte-dominated and phytoplankton-dominated water regimes. An ecosystem regime shift from macrophytes to phytoplankton blooming typically reduces the number of species of invertebrates and fishes and results in the homogenization of communities in freshwater lakes. We investigated how microbial biodiversity has responded to a shift of the ecosystem regime in Dianchi Lake, which was previously fully covered with submerged macrophytes but currently harbors both ecological states. We observed marked divergence in the diversity and community composition of bacterioplankton between the two regimes. Although species richness, estimated as the number of operational taxonomic units and phylogenetic diversity (PD), was higher in the phytoplankton dominated ecosystem after this shift, the dissimilarity of bacterioplankton community across space decreased. This decrease in beta diversity was accompanied by loss of planktonic bacteria unique to the macrophyte-dominated ecosystem. Mantel tests between bacterioplankton community distances and Euclidian distance of environmental parameters indicated that this reduced bacterial community diff erentiation primarily reflected the loss of environmental niches, particularly in the macrophyte regime. The loss of this small-scale heterogeneity in bacterial communities should be considered when assessing long-term biodiversity changes in response to ecosystem regime conversions in freshwater lakes.

  9. Water Properties Influencing the Abundance and Diversity of Denitrifiers on Eichhornia crassipes Roots: A Comparative Study from Different Effluents around Dianchi Lake, China

    PubMed Central

    Yi, Neng; Gao, Yan; Zhang, Zhenhua; Shao, Hongbo; Yan, Shaohua

    2015-01-01

    To evaluate effects of environmental conditions on the abundance and communities of three denitrifying genes coding for nitrite (nirK, nirS) reductase and nitrous oxide (nosZ) reductase on the roots of Eichhornia crassipes from 11 rivers flowing into the northern part of Dianchi Lake. The results showed that the abundance and community composition of denitrifying genes on E. crassipes root varied with different rivers. The nirK gene copies abundance was always greater than that of nirS gene on the roots of E. crassipes, suggesting that the surface of E. crassipes roots growth in Dianchi Lake was more suitable for the growth of nirK-type denitrifying bacteria. The DGGE results showed significant differences in diversity of denitrifying genes on the roots of E. crassipes among the 11 rivers. Using redundancy analysis (RDA), the correlations of denitrifying microbial community compositions with environmental factors revealed that water temperature (T), dissolved oxygen (DO), and pH were relatively important environmental factors to modifying the community structure of the denitrifying genes attached to the root of E. crassipes. The results indicated that the specific environmental conditions related to different source of rivers would have a stronger impact on the development of denitrifier communities on E. crassipes roots. PMID:26495277

  10. Water Properties Influencing the Abundance and Diversity of Denitrifiers on Eichhornia crassipes Roots: A Comparative Study from Different Effluents around Dianchi Lake, China.

    PubMed

    Yi, Neng; Gao, Yan; Zhang, Zhenhua; Shao, Hongbo; Yan, Shaohua

    2015-01-01

    To evaluate effects of environmental conditions on the abundance and communities of three denitrifying genes coding for nitrite (nirK, nirS) reductase and nitrous oxide (nosZ) reductase on the roots of Eichhornia crassipes from 11 rivers flowing into the northern part of Dianchi Lake. The results showed that the abundance and community composition of denitrifying genes on E. crassipes root varied with different rivers. The nirK gene copies abundance was always greater than that of nirS gene on the roots of E. crassipes, suggesting that the surface of E. crassipes roots growth in Dianchi Lake was more suitable for the growth of nirK-type denitrifying bacteria. The DGGE results showed significant differences in diversity of denitrifying genes on the roots of E. crassipes among the 11 rivers. Using redundancy analysis (RDA), the correlations of denitrifying microbial community compositions with environmental factors revealed that water temperature (T), dissolved oxygen (DO), and pH were relatively important environmental factors to modifying the community structure of the denitrifying genes attached to the root of E. crassipes. The results indicated that the specific environmental conditions related to different source of rivers would have a stronger impact on the development of denitrifier communities on E. crassipes roots.

  11. Dynamic monitoring and prediction of Dianchi Lake cyanobacteria outbreaks in the context of rapid urbanization.

    PubMed

    Luo, Yi; Yang, Kun; Yu, Zhenyu; Chen, Junyi; Xu, Yufei; Zhou, Xiaolu; Yang, Yang

    2017-02-01

    Water crises have been among the most serious environmental problems worldwide since the twenty-first century. A water crisis is marked by a severe shortage of water resources and deteriorating water quality. As an important component of water resources, lake water quality has deteriorated rapidly in the context of fast urbanization and climate change. This deterioration has altered the water ecosystem structure and influenced lake functionality. To curb these trends, various strategies and procedures have been used in many urban lakes. Among these procedures, accurate and responsive water environment monitoring is the basis of the forecasting and prevention of large-scale cyanobacteria outbreaks and improvement of water quality. To dynamically monitor and predict the outbreak of cyanobacteria in Dianchi Lake, in this study, wireless sensors networks (WSNs) and the geographic information system (GIS) are used to monitor water quality at the macro-scale and meso-scale. Historical, real-time water quality and weather condition data were collected, and a combination prediction model (adaptive grey model (AGM) and back propagation artificial neural network (BPANN)) was proposed. The correlation coefficient (R) of the simulation experiment reached 0.995. Moreover, we conducted an empirical experiment in Dianchi Lake, Yunnan, China using the proposed method. R was 0.93, and the predicting error was 4.77. The results of the experiment suggest that our model has good performance for water quality prediction and can forecast cyanobacteria outbreaks. This system provides responsive forewarning and data support for lake protection and pollution control.

  12. Quantitative and qualitative characteristics of dissolved organic matter from eight dominant aquatic macrophytes in Lake Dianchi, China.

    PubMed

    Qu, Xiaoxia; Xie, Li; Lin, Ying; Bai, Yingchen; Zhu, Yuanrong; Xie, Fazhi; Giesy, John P; Wu, Fengchang

    2013-10-01

    The aim of this research was to determine and compare the quantitative and qualitative characteristics of dissolved organic matters (DOM) from eight aquatic macrophytes in a eutrophic lake. C, H, N, and P in ground dry leaves and C, N, and P in DOM of the species were determined, and C/N, C/P, C/H, DOC/C, TDN/N, TDP/P, DOC/TDN, and DOC/TDP were calculated. Chemical structures of the DOM were characterized by the use of multiple techniques including UV-visible, FT-IR, and (13)C CP/MAS spectra. The results showed subtle differences in quantity and quality of DOM among species and life-forms. Except oriental pepper which had a C/H of 0.7, C/H of all the other species was 0.6. C/N and C/P of ground leaves was 10.5-17.3 and 79.4-225.3, respectively, which were greater in floating and submerged species than in the others. Parrot feather also had a small C/P (102.8). DOC/C, TDN/N, and TDP/P were 7.6-16.8, 5.5-22.6, and 22.9-45.6 %, respectively. Except C/N in emergent and riparian species, C/N in the other species and C/P in all the species were lower in their DOM than in the ground leaves. DOM of the macrophytes had a SUVA254 value of 0.83-1.80. The FT-IR and (13)C NMR spectra indicated that the DOM mainly contained polysaccharides and/or amino acids/proteins. Percent of carbohydrates in the DOM was 37.3-66.5 % and was highest in parrot feather (66.5 %) and crofton weed (61.5 %). DOM of water hyacinth, water lettuce, and sago pondweed may have the greatest content of proteins. Aromaticity of the DOM was from 6.9 % in water lettuce to 17.8 % in oriental pepper. DOM of the macrophytes was also different in polarity and percent of Ar-OH. Distinguished characteristics in quantity and quality of the macrophyte-derived DOM may induce unique environmental consequences in the lake systems.

  13. [Dianchi Lake macroinvertebrate community succession trends and retrogressive analysis].

    PubMed

    Wang, Chou-Ming; Xie, Zhi-Cai; Song, Li-Rong; Xiao, Bang-Ding; Li, Gen-Bao; Li, Lin

    2011-04-01

    Historical records and data from yield surveys conducted in 2009 and 2010 were used to investigate macroinvertebrate community succession trends in Dianchi Lake. Species richness has declined from 57 in the 1980s to 32 in 2010, representing a species loss of 44%. Among the major benthic groups, the highest rate of loss was recorded for mollusks (75%) and aquatic insects (39%). Surveys in 2009 and 2010 across the lake revealed that the total density was 1776 ind/m2, comprising oligochaetes (1706 ind/m2) and chironomids (68 ind/m2). Over a nearly twenty-year span (1992-2010), the density and biomass of oligochaetes first increased sharply (1992-2002) and then declined gradually (2002-2010). Further, chironomids have decreased gradually while the proportion of abundant species has increased. Limnodrilus hoffmeisteri became the sole dominant species with an average relative abundance of 74.1%. Cosmopolitan species, such as Einfeldia sp., disappeared across the lake; instead, tolerant species such as Chironomus plumosus, Ch. attenuatus and Tanypus chinensis became the common. Mollusk community structure has become simpler and many native species have gone extinct. Species of concern include Margarya melanioides, M. mondi, M. mansugi and Cipangopaludina dianchiensis, all rated as critically endangered by the IUCN. We found that the Shannon-Wiener index declined in Dianchi Lake, particularly in Caohai Lake, from 2.70 in the 1950s to 0.30 in 2009 and 2010. Species richness and biodiversity was significantly negative correlated with total phosphorus and total nitrogen. Factors responsible for the benthic community retrogression described here include habitat destruction, lowering of water quality, outbreaks of blue-green algae, extinction of submerged plants and lack of germplasm resources.

  14. [Impacts of human disturbance on the species composition of higher plants in the wetlands around Dianchi Lake, Yunnan Province of Southwest China].

    PubMed

    Xiang, Xi-Xi; Wu, Zhao-Lu; Luo, Kang; Ding, Hong-Bo; Zhang, Hai-Yan

    2013-09-01

    Introducing higher plants to build semi-natural wetland ecosystem is one of the key approaches to restore the wetlands and lakes that suffered from serious pollution and destruction. Based on the investigation data from 128 quadrats at 26 sampling sites in the wetlands around Dianchi Lake in December 2011-October 2012, and in combining with the references published in the 1960s, this paper discussed the impacts of human activities on the species composition of higher plants in the wetlands around the Lake. In 2012, there were 299 species of 88 families in the wetlands, of which, 181 species were native species, and 118 species were alien ones (including 32 invasive species). Of the 42 species of hydrophytes in the total species, 13 species were alien ones (including 2 invasive species). In comparing with the species data recorded in the 1960s, 232 plants were newly recorded and 43 species disappeared in 2012. Aquatic plants changed obviously. The decreased species were 2 submerged plants, 2 floating plants, and 5 floating leaved plants, and the increased species were 8 emergent plants. Fourteen community types were identified by cluster analysis, of which, the main communities were those dominated by alien species including Pistia stratiotes and Alternanthera philoxeroides. As compared with the data in the 1960s, the plant communities dominated by native species such as Ottelia acuminate and Vallisneria natans were not found presently. Therefore, in the practice of introducing higher plants to restore the degraded wetlands and lakes, it would be necessary to scientifically and appropriately select and blend plant species to avoid the wetland degradation by human activities.

  15. Analysis on the Climate Change Characteristics of Dianchi Lake Basin under the Background of Global Warming

    NASA Astrophysics Data System (ADS)

    Zhenyu, Yu; Luo, Yi; Yang, Kun; Qiongfei, Deng

    2017-05-01

    Based on the data published by the State Statistical Bureau and the weather station data, the annual mean temperature, wind speed, humidity, light duration and precipitation of Dianchi Lake in 1990 ~ 2014 were analysed. Combined with the population The results show that the climatic changes in Dianchi Lake basin are related to the climatic change in the past 25 years, and the correlation between these factors and the main climatic factors are analysed by linear regression, Mann-Kendall test, cumulative anomaly, R/S and Morlet wavelet analysis. Population, housing construction area growth and other aspects of the correlation trends and changes in the process, revealing the population expansion and housing construction area growth on the climate of the main factors of the cycle tendency of significant impact.

  16. Phosphorus mobility among sediments, water and cyanobacteria enhanced by cyanobacteria blooms in eutrophic Lake Dianchi.

    PubMed

    Cao, Xin; Wang, Yiqi; He, Jian; Luo, Xingzhang; Zheng, Zheng

    2016-12-01

    This study was focused on the phosphorus mobility among sediments, water and cyanobacteria in eutrophic Lake Dianchi. Four conditions lake water, water and algae, water and sediments, and three objects together were conducted to investigate the effects of cyanobacteria growth on the migration and transformation of phosphorus. Results showed a persistent correlation between the development of cyanobacterial blooms and the increase of soluble reactive phosphorus (SRP) in the lake water under the condition of three objects together. Time-course assays measuring different forms of phosphorus in sediments indicated that inorganic phosphorus (IP) and NaOH-P were relatively more easier to migrate out of sediment to the water and cyanobacteria. Further studies on phosphorus mobility showed that up to 70.2% of the released phosphorus could be absorbed by cyanobacteria, indicating that sediment is a major source of phosphorus when external loading is reduced. Time-course assays also showed that the development of cyanobacterial blooms promoted an increase in pH and a decrease in the redox potential of the lake water. The structure of the microbial communities in sediments was also significantly changed, revealed a great impaction of cyanobacterial blooms on the microbial communities in sediments, which may contribute to phosphorus release. Our study simulated the cyanobacterial blooms of Lake Dianchi and revealed that the cyanobacterial blooms is a driving force for phosphorus mobility among sediments, water and cyanobacteria. The outbreak of algal blooms caused deterioration in water quality. The P in the sediments represented a significant supply for the growth of cyanobacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Linear alkylbenzene sulfonate (LAS) in water of Lake Dianchi--spatial and seasonal variation, and kinetics of biodegradation.

    PubMed

    Wang, Zhi; Xiao, Bangding; Wu, Xingqiang; Tu, Xinhai; Wang, Yingcai; Sun, Xiaolei; Song, Lirong

    2010-12-01

    For the purpose of elucidating the environmental characteristics of anion surfactants [linear alkylbenzene sulfonates (LAS)] in the water of Lake Dianchi, a sampling investigation in the field from October 2006 to July 2007 and a batch of biodegradation experiments in the laboratory were carried out. The results showed that concentrations of LAS ranged from 18.6 to 260.1 μg L(-1), and the average concentration was 52.6 μg L(-1) in Lake Dianchi. The highest concentrations of LAS were found in the Northwest region, and the distribution of LAS varied through seasons, with much lower concentrations in fall than in any other seasons. LAS can be primarily biodegraded by microorganisms in the lake water, and the percentage of degradation was >97% after 28 days. Biodegradation of LAS was well-fitted with the kinetic model presented in this paper, and the half-lives ranged from 3.2 to 16.3 days. Temperature, pH, and initial concentrations could affect the biodegradation of LAS, among which temperature was the major factor influencing on biodegradation of LAS in water of Lake Dianchi.

  18. Enhanced N input to Lake Dianchi Basin from 1980 to 2010: drivers and consequences.

    PubMed

    Gao, Wei; Howarth, Robert W; Swaney, Dennis P; Hong, Bongghi; Guo, Huai Cheng

    2015-02-01

    Due to a rapid increase in human population and development of neighborhood economy over the last few decades, nitrogen (N) and other nutrient inputs in Lake Dianchi drainage basin have increased dramatically, changing the lake's trophic classification from oligotrophic to eutrophic. Although human activities are considered as main causes for the degradation of water quality in the lake, a numerical analysis of the share of the effect of different anthropogenic factors is still largely unexplored. We use the net anthropogenic N input (NANI) method to estimate human-induced N inputs to the drainage basin from 1980 to 2010, which covers the period of dramatic socioeconomic and environmental changes. For the last three decades, NANI increased linearly by a factor of three, from 4700 kg km(-2)year(-1) in 1980 to 12,600 kg km(-2)year(-1) in 2010. The main reason for the rise of NANI was due to fertilizer N application as well as human food and animal feed imports. From the perspective of direct effects of food consumption on N inputs, contributions of drivers were estimated in terms of human population and human diet using the Logarithmic Mean Divisia Index (LMDI) factor decomposition method. Although human population density is highly correlated to NANI with a linear correlation coefficient of 0.999, human diet rather than human population is found to be the single largest driver of NANI change, accounting for 47% of total alteration, which illustrates that the role of population density in the change of NANI may be overestimated through simple relational analysis. The strong linear relationships (p<0.01) between NANI and total N concentrations in the lakes over time may indicate that N level in the lake is able to respond significantly to N inputs to the drainage basin. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. [Biodegradation of LAS in the anaerobic water of a representative inlet of Lake Dianchi].

    PubMed

    Wang, Zhi; Tu, Xin-hai; Xiao, Bang-ding; Wu, Xing-qiang; Liu, Min; Chen, Xu-dong

    2008-08-01

    Biodegradation and degradation kinetics of anion-surfactant (LAS) in the anaerobic water of a representative inlet (Haihe River) of Lake Dianchi under different incubation conditions were studied by the 'river die-away' test method. The influences of temperature, pH, initial concentration of LAS, aeration condition and added nutrients (NH4Cl or NaH2PO4) on the biodegradation of LAS in the water were investigated. The results demonstrate that LAS can be biodegraded by microorganisms in the water and that the percentage of degradation of LAS was more than 95% after 26 d. The biodegradation of LAS fit the second kinetic model. Incubation temperature, initial concentration of LAS, aeration and added nutrients (NH4Cl or NaH2PO4) can all affect the biodegradation of LAS. When the incubation temperature increased from 10 degrees C to 25 degrees C, the biodegradation rate (p) of LAS increased from 0.21 d(-1) to 0.90 d(-1). The LAS degradation rate increased from 0.72 d(-1) under anaerobic condition to 1.97 d(-1) under continuous aeration condition. The increased initial concentrations of LAS lead to decrease of the biodegradation rate. NaH2PO4 accelerated the degradation of LAS but added NH4Cl instead inhibited degradation. In our experiment, pH value (7.05-9.44) had little influence on the biodegradation of LAS.

  20. [First flush effects of storm events of Baoxiang River in Lake Dianchi Watershed].

    PubMed

    Guo, Huai-Cheng; Xiang, Nan; Zhou, Feng; Wang, Yong-Hua; Li, Fa-Rong; Zhu, Xiang; Mao, Guo-Zhu; Yu, Shu-Xia; Li, Na; Sheng, Hu; Yang, Yong-Hui; He, Cheng-Jie; Wang, Cui-Yu

    2013-04-01

    To understand riverine process of non-point source effectively, first flush effects of storm events were investigated at Baoxiang River of Lake Dianchi Watershed. Three sampling stations were selected along Baoxiang River for observing the flow rate and pollutant concentrations of the first three storm events from June 2009 to August 2009. Net discharged volume, net discharged loading, and net event mean concentration (EMC(n)) were proposed with their calculation methods. According to the analysis of three storm events at three stations, the following results colcd be extracted: (1) the larger the percent of impervious land and population density were, the higher EMC(n) of TSS, TN, TP, permanganate index and their cumulative curves [M(V)] were along the river; (2) TSS, TP loadings as well as their M (V) were positively correlated to the storm intensity, while TN and permanganate index loadings were consistent with the total rainfall of each storm event, where the percent of NO3(-) -N in total nitrogen decreased gradually when the number of storm events increased; (3) compared to tradition EMC, EMC(n) was proven to be a better indicator to accurately uncover and magnify the differences in first flush effects of storm events among different stations or storm events.

  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. New insights into the source of decadal increase in chemical oxygen demand associated with dissolved organic carbon in Dianchi Lake.

    PubMed

    Guo, Wei; Yang, Feng; Li, Yanping; Wang, Shengrui

    2017-12-15

    Dissolved organic carbon (DOC) can be used an alternative index of water quality instead of chemical oxygen demand (COD) to reflect the organic pollution in water. The monitoring data of water quality in a long-term (1990-2013) from Dianchi Lake confirmed the increase trend of COD concentration in the lake since 2007. The similarities and differences in the DOC components between the lake and its sources and the contribution from allochthonous and autochthonous DOC to the total DOC in this lake were determined to elucidate the reason of COD increase based on C/N atomic ratios, stable isotope abundance of carbon and nitrogen, UV-visible spectroscopy, three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy. The terrigenous organic matter showed humic-like fluorescence, and the autochthonous organic matter showed tryptophan-like components. Agricultural runoff (9.5%), leaf litter (7.5%) and urban runoff (13.2%) were the main sources of DOC in the lake. Sewage tail was a major source of organic materials, 3DEEM for the indicates that sewage tail DOC composition did not change markedly over the biodegradation period, indicating that sewage tail contains a high load of DOC that is resistant to further biodegradation and subsequently accumulates in the lake. The change of land use in the catchment and the increase of sewage tail load into the lake are the key factors for the increase in COD concentration in Dianchi Lake. Thus, the lake should be protected by controlling the pollution from the urban nonpoint sources and refractory composition in point sources. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Sediment Ammonia-Oxidizing Microorganisms in Two Plateau Freshwater Lakes at Different Trophic States.

    PubMed

    Yang, Yuyin; Zhang, Jingxu; Zhao, Qun; Zhou, Qiheng; Li, Ningning; Wang, Yilin; Xie, Shuguang; Liu, Yong

    2016-02-01

    Both ammonia-oxidizing archaea (AOA) and bacteria (AOB) can contribute to ammonia biotransformation in freshwater lake ecosystems. However, the factors shaping the distribution of sediment AOA and AOB in plateau freshwater lake remains unclear. The present study investigated sediment AOA and AOB communities in two freshwater lakes (hypertrophic Dianchi Lake and mesotrophic Erhai Lake) on the Yunnan Plateau (China). A remarkable difference in the abundance, diversity, and composition of sediment AOA and AOB communities was observed between Dianchi Lake and Erhai Lake. AOB usually outnumbered AOA in Dianchi Lake, but AOA showed the dominance in Erhai Lake. Organic matter (OM), total nitrogen (TN), and total phosphorus (TP) might be the key determinants of AOB abundance, while AOA abundance was likely influenced by the ration of OM to TN (C/N). AOA or AOB community structure was found to be relatively similar in the same lake. TN and TP might play important roles in shaping sediment AOA and AOB compositions in Dianchi Lake and Erhai Lake. Moreover, Nitrososphaera-like AOA were detected in Dianchi Lake. Nitrosospira- and Nitrosomonas-like AOB were dominant in Dianchi Lake and Erhai Lake, respectively. Sediment AOA and AOB communities in Dianchi Lake and Erhai Lake were generally regulated by trophic state.

  4. Hydrothermal liquefaction of harvested high-ash low-lipid algal biomass from Dianchi Lake: effects of operational parameters and relations of products.

    PubMed

    Tian, Chunyan; Liu, Zhidan; Zhang, Yuanhui; Li, Baoming; Cao, Wei; Lu, Haifeng; Duan, Na; Zhang, Li; Zhang, Tingting

    2015-05-01

    Hydrothermal liquefaction (HTL) allows a direct conversion of algal biomass into biocrude oil, not only solving the environmental issues caused by the over-growing algae but also producing renewable energy. This study reports HTL of algae after separation from eutrophicated Dianchi Lake in China. Conversion efficiency was studied under different operational conditions via an orthogonal design, including holding temperature (HT) (260-340 °C), retention time (RT) (30-90 min) and total solid (TS) (10-20%). A highest biocrude oil yield (18.4%, dry ash-free basis, daf) was achieved at 300 °C, 60 min, and 20% (TS), due to the low contents of lipids (1.9%, daf) and proteins (24.8%, daf), and high contents of ash (41.6%, dry basis) and carbohydrates (71.8%, daf). Operational parameters significantly affected the biocrude yields, and chemical distribution of HTL products. The biocrude production also related to other HTL products, and involved chemical reactions, such as deoxygenation and/or denitrogenation.

  5. Risk of phosphorus leaching from phosphorus-enriched soils in the Dianchi catchment, Southwestern China.

    PubMed

    Li, Meng; Hu, Zhengyi; Zhu, Xiaoqi; Zhou, Guohui

    2015-06-01

    As an important pathway for phosphorus (P) transport from soil to water body, P leaching has aroused attention. This study aimed to investigate the degree of risk and forms of P leaching from P-enriched soils. Surface soils were collected from forest land (FL) and open agricultural land (OAL) in typical P-enriched area of the Dianchi catchment, China. Based on analysis of soil P and water-soluble P using chemical methods and (31)P-NMR analysis, combined with a soil column leaching experiment, P forms and risk of P leaching were identified. CaCl2-extractable water-soluble organic P (CaCl2-Po), inorganic P (CaCl2-Pi), and total P (CaCl2-P) extracted using 0.01-M CaCl2 solution were found to be useful for predicting potential organic and inorganic P leaching, given a linear, positive correlation between CaCl2-P, CaCl2-Pi, and CaCl2-Po in soils and accumulated amounts of corresponding P forms in soil leachates. The majority of investigated FL was at or above the change points of 46, 46, and 42 mg AP kg(-1) for CaCl2-Pi, CaCl2-Po, and CaCl2-P, respectively, and thus at a risk of P leaching. Organic and inorganic P leaching was present in nearly all investigated OAL. CaCl2-Po accounted for 66.0 % of CaCl2-P in FL and 56.1 % in OAL. Signals of (31)P-NMR spectra were mainly attributable to orthophosphate, orthophosphate monoesters, and orthophosphate diesters in FL and OAL soils. It is important to consider P loss due to leaching of inorganic and organic P in P-enriched areas.

  6. Comparison and Interpretation of Taxonomical Structure of Bacterial Communities in Two Types of Lakes on Yun-Gui plateau of China

    PubMed Central

    Han, Maozhen; Gong, Yanhai; Zhou, Chunyu; Zhang, Junqian; Wang, Zhi; Ning, Kang

    2016-01-01

    Bacterial communities from freshwater lakes are shaped by various factors such as nutrients, pH value, temperature, etc. Their compositions and relative abundances would undergo changes to adapt the changing environments, and in turn could affect the environments of freshwater lakes. Analyses of the freshwater lake’s bacterial communities under different environments would be of pivotal importance to monitor the condition of waterbody. In this study, we have collected freshwater samples from two lakes on Yun-Gui plateau of China, Lake Dianchi and Lake Haixihai, and analyzed the bacterial community structures from these samples based on 16S rRNA sequencing. Results have shown that: Firstly, the bacterial community of these samples have very different taxonomical structures, not only between two lakes but also among the intra-groups for samples collected from Dianchi. Secondly, the differences between samples from two lakes are highly associated with the chemical-geographical properties of the two lakes. Thirdly, for samples of Dianchi and Haixihai, analytical results of physicochemical, taxonomical structure and relative abundance of community revealed that extreme physicochemical factors caused by human activities have strongly affected the bacterial ecosystem in Dianchi. These results have clearly indicated the importance of combining biological profiling and chemical-geographical properties for monitoring Chinese plateau freshwater bacterial ecosystem, which could provide clues for Chinese freshwater ecosystem remediation on plateau. PMID:27461070

  7. Bottom-up versus top-down effects on ciliate community composition in four eutrophic lakes (China).

    PubMed

    Li, Jing; Chen, Feizhou; Liu, Zhengwen; Zhao, Xiuxia; Yang, Kun; Lu, Wenxuan; Cui, Kai

    2016-04-01

    Previous studies have shown that ciliate plankton is generally controlled by food resources (e.g., algae) and predators (e.g., metazooplankton). Among lakes with similar trophic levels but different distributions of phyto- and metazooplankton, the main forces acting on ciliate assemblages may be different. We investigated the relationship between ciliate communities and bottom-up versus top-down variables based on a survey of four subtropical eutrophic lakes (China). Two of the lakes (Chaohu, Taihu) are located on the Mid-lower Yangtze Plain near sea level, and the other two (Dianchi, Xingyunhu) on the Yunnan-Kweichow Plateau at 1700 m above sea level. Blooms of cyanobacteria developed during summer in Lakes Chaohu and Taihu and throughout the year in Lakes Dianchi and Xingyunhu. Ciliate functional feeding groups differed significantly between lakes. The results of canonical correspondence analysis (CCA) and variation partitioning showed that cyanobacteria significantly influence ciliate species, whereas 'edible' algae (cryptophytes, diatoms) and cladocerans were the important variables in explaining the ciliate community structure of Lakes Dianchi and Xingyunhu compared with Lakes Taihu and Chaohu. Our results highlight the importance of consistent cyanobacterial blooms in shaping the ciliate community in subtropical eutrophic shallow lakes by interacting with top-down and bottom-up factors. Copyright © 2016 Elsevier GmbH. All rights reserved.

  8. Spatiotemporal variation of planktonic and sediment bacterial assemblages in two plateau freshwater lakes at different trophic status.

    PubMed

    Dai, Yu; Yang, Yuyin; Wu, Zhen; Feng, Qiuyuan; Xie, Shuguang; Liu, Yong

    2016-05-01

    Both planktonic and sediment bacterial assemblages are the important components of freshwater lake ecosystems. However, their spatiotemporal shift and the driving forces remain still elusive. Eutrotrophic Dianchi Lake and mesotrophic Erhai Lake are the largest two freshwater lakes on the Yunnan Plateau (southwestern China). The present study investigated the spatiotemporal shift in both planktonic and sediment bacterial populations in these two plateau freshwater lakes at different trophic status. For either lake, both water and sediment samples were collected from six sampling locations in spring and summer. Bacterioplankton community abundance in Dianchi Lake generally far outnumbered that in Erhai Lake. Sediment bacterial communities in Erhai Lake were found to have higher richness and diversity than those in Dianchi Lake. Sediments had higher bacterial community richness and diversity than waters. The change patterns for both planktonic and sediment bacterial communities were lake-specific and season-specific. Either planktonic or sediment bacterial community structure showed a distinct difference between in Dianchi Lake and in Erhai Lake, and an evident structure difference was also found between planktonic and sediment bacterial communities in either of these two lakes. Planktonic bacterial communities in both Dianchi Lake and Erhai Lake mainly included Proteobacteria (mainly Alpha-, Beta-, and Gammaproteobacteria), Bacteroidetes, Actinobacteria, Cyanobacteria, and Firmicutes, while sediment bacterial communities were mainly represented by Proteobacteria (mainly Beta- and Deltaproteobacteria), Bacteroidetes, Chlorobi, Nitrospirae, Acidobacteria, and Chloroflexi. Trophic status could play important roles in shaping both planktonic and sediment bacterial communities in freshwater lakes.

  9. Temporal and Spatial Dynamics of Sediment Anaerobic Ammonium Oxidation (Anammox) Bacteria in Freshwater Lakes.

    PubMed

    Yang, Yuyin; Dai, Yu; Li, Ningning; Li, Bingxin; Xie, Shuguang; Liu, Yong

    2017-02-01

    Anaerobic ammonium-oxidizing (anammox) process can play an important role in freshwater nitrogen cycle. However, the distribution of anammox bacteria in freshwater lake and the associated environmental factors remain essentially unclear. The present study investigated the temporal and spatial dynamics of sediment anammox bacterial populations in eutrotrophic Dianchi Lake and mesotrophic Erhai Lake on the Yunnan Plateau (southwestern China). The remarkable spatial change of anammox bacterial abundance was found in Dianchi Lake, while the relatively slight spatial shift occurred in Erhai Lake. Dianchi Lake had greater anammox bacterial abundance than Erhai Lake. In both Dianchi Lake and Erhai Lake, anammox bacteria were much more abundant in summer than in spring. Anammox bacterial community richness, diversity, and structure in these two freshwater lakes were subjected to temporal and spatial variations. Sediment anammox bacterial communities in Dianchi Lake and Erhai Lake were dominated by Candidatus Brocadia and a novel phylotype followed by Candidatus Kuenenia; however, these two lakes had distinct anammox bacterial community structure. In addition, trophic status determined sediment anammox bacterial community structure.

  10. Distribution of arsenic between the particulate and aqueous phases in surface water from three freshwater lakes in China.

    PubMed

    Yang, Fen; Geng, Di; Wei, Chaoyang; Ji, Hongbing; Xu, Hai

    2016-04-01

    Total arsenic (As) in suspended particulate matter (SPM) of lacustrine ecosystems has been extensively documented, but knowledge on the distribution of As between the particle and aqueous phases in freshwater lakes remains largely unknown. The present study employed a rapid method to determine the total and dissolved As and As in SPM at sites covering the entire areas of three large shallow lakes in China, e.g., Taihu, Chaohu, and Dianchi, to obtain a "representative" mean value of the As concentration in various phases. The average concentrations of total and dissolved As were below 6.0 and 3.3 μg/L, respectively. Arsenic in SPM was much higher than that in waters, as ranging from 24.7 to 516 μg/g. Lake Taihu exhibited extensive seasonal variation both in total and dissolved As, while little difference was observed in SPM concentration, with an average value of 54.2 and 49.3 mg/L in winter and summer, respectively. Among the algae in the three lakes, Cyanophyta dominated in both cell abundance and biomass. Algae mass occupied significant parts of SPM, especially in Dianchi; the proportions of algae in the SPM fractions were measured as 10.4 and 7.1 % in Taihu in winter and summer, 4.5 % in Chaohu, and 53.3 % in Dianchi, both in summer season. The total As in SPM had a significant positive relationship with total As in water and a high distribution coefficient (Kd) between SPM and dissolved fraction of As at all three lakes. The high proportions of Algae, especially Cyanophyta in the composition of SPM in the three large shallow lakes, might play an important role in affecting the As distribution between the aqueous and particulate phases in aquatic ecosystem.

  11. Dongting Lake, China

    NASA Image and Video Library

    2002-09-15

    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. http://photojournal.jpl.nasa.gov/catalog/PIA03858

  12. 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

  13. 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

  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. Quantitative evaluation of lake eutrophication responses under alternative water diversion scenarios: a water quality modeling based statistical analysis approach.

    PubMed

    Liu, Yong; Wang, Yilin; Sheng, Hu; Dong, Feifei; Zou, Rui; Zhao, Lei; Guo, Huaicheng; Zhu, Xiang; He, Bin

    2014-01-15

    China is confronting the challenge of accelerated lake eutrophication, where Lake Dianchi is considered as the most serious one. Eutrophication control for Lake Dianchi began in the mid-1980s. However, decision makers have been puzzled by the lack of visible water quality response to past efforts given the tremendous investment. Therefore, decision makers desperately need a scientifically sound way to quantitatively evaluate the response of lake water quality to proposed management measures and engineering works. We used a water quality modeling based scenario analysis approach to quantitatively evaluate the eutrophication responses of Lake Dianchi to an under-construction water diversion project. The primary analytic framework was built on a three-dimensional hydrodynamic, nutrient fate and transport, as well as algae dynamics model, which has previously been calibrated and validated using historical data. We designed 16 scenarios to analyze the water quality effects of three driving forces, including watershed nutrient loading, variations in diverted inflow water, and lake water level. A two-step statistical analysis consisting of an orthogonal test analysis and linear regression was then conducted to distinguish the contributions of various driving forces to lake water quality. The analysis results show that (a) the different ways of managing the diversion projects would result in different water quality response in Lake Dianchi, though the differences do not appear to be significant; (b) the maximum reduction in annual average and peak Chl-a concentration from the various ways of diversion project operation are respectively 11% and 5%; (c) a combined 66% watershed load reduction and water diversion can eliminate the lake hypoxia volume percentage from the existing 6.82% to 3.00%; and (d) the water diversion will decrease the occurrence of algal blooms, and the effect of algae reduction can be enhanced if diverted water are seasonally allocated such that wet

  16. 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.

  17. Is water age a reliable indicator for evaluating water quality effectiveness of water diversion projects in eutrophic lakes?

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoling; Zou, Rui; Wang, Yilin; Liu, Yong; Zhao, Lei; Zhu, Xiang; Guo, Huaicheng

    2016-11-01

    Water diversion has been applied increasingly to promote the exchange of lake water and to control eutrophication of lakes. The accelerated water exchange and mass transport by water diversion can usually be represented by water age. But the responses of water quality after water diversion is still disputed. The reliability of using water age for evaluating the effectiveness of water diversion projects in eutrophic lakes should be thereby explored further. Lake Dianchi, a semi-closed plateau lake in China, has suffered severe eutrophication since the 1980s, and it is one of the three most eutrophic lakes in China. There was no significant improvement in water quality after an investment of approximately 7.7 billion USD and numerous project efforts from 1996 to 2015. After the approval of the Chinese State Council, water has been transferred to Lake Dianchi to alleviate eutrophication since December 2013. A three-dimensional hydrodynamic and water quality model and eight scenarios were developed in this study to quantity the influence of this water diversion project on water quality in Lake Dianchi. The model results showed that (a) Water quality (TP, TN, and Chla) could be improved by 13.5-32.2%, much lower than the approximate 50% reduction in water age; (b) Water exchange had a strong positive relationship with mean TP, and mean Chla had exactly the same response to water diversion as mean TN; (c) Water level was more beneficial for improving hydrodynamic and nutrient concentrations than variation in the diverted inflowing water volume; (d) The water diversion scenario of doubling the diverted inflow rate in the wet season with the water level of 1886.5 m and 1887 m in the remaining months was the best water diversion mode for mean hydrodynamics and TP, but the scenario of doubling the diverted inflow rate in the wet season with 1887 m throughout the year was optimum for mean TN and Chla; (e) Water age influenced the effectiveness of water diversion on the

  18. 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.

  19. 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.

  20. Vertical profiles of sediment methanogenic potential and communities in two plateau freshwater lakes

    NASA Astrophysics Data System (ADS)

    Yang, Yuyin; Li, Ningning; Wang, Wei; Li, Bingxin; Xie, Shuguang; Liu, Yong

    2017-01-01

    Microbial methanogenesis in sediment plays a crucial role in CH4 emission from freshwater lake ecosystems. However, knowledge of the layer-depth-related changes of methanogen community structure and activities in freshwater lake sediment is still limited. The present study was conducted to characterize the methanogenesis potential in different sediment-layer depths and the vertical distribution of microbial communities in two freshwater lakes of different trophic status on the Yunnan Plateau (China). Incubation experiments and inhibitor studies were carried out to determine the methanogenesis potential and pathways. 16S rRNA and mcrA genes were used to investigate the abundance and structure of methanogen and archaeal communities, respectively. Hydrogenotrophic methanogenesis was mainly responsible for methane production in sediments of both freshwater lakes. The layer-depth-related changes of methanogenesis potential and the abundance and community structure of methanogens were observed in both Dianchi Lake and Erhai Lake. Archaeal 16S rRNA and mcrA genes displayed a similar abundance change pattern in both lakes, and the relative abundance of methanogens decreased with increasing sediment-layer depth. Archaeal communities differed considerably in Dianchi Lake and Erhai Lake, but methanogen communities showed a slight difference between these two lakes. However, methanogen communities illustrated a remarkable layer-depth-related change. Order Methanomicrobiales was the dominant methanogen group in all sediments, while Methanobacteriales showed a high proportion only in upper layer sediments. The trophic status of the lake might have a notable influence on the depth-related change pattern of methanogenesis activity, while the methanogen community structure was mainly influenced by sediment depth.

  1. Lake salinity variations resulting from wind direction, Gobi Desert, China

    NASA Astrophysics Data System (ADS)

    Bradley, D. C.; Cartwright, I.; Currell, M.

    2010-12-01

    The southern reaches of the Gobi desert, central China, host a large number (~50) of shallow (<3m depth), narrow, north-south trending through-flow lakes. The size of the sand dunes (many over 150m) in this area means that the valleys between the largest dunes can intersect with the water table. The resultant lakes are of particular interest, not only because they are host to a number of unique ecosystems, including several rare species, but also because they are very susceptible to environmental disturbances. Physical development of the lakes is a clear threat, but also small scale withdrawal of groundwater in proximity to the lakes can cause a drop in the water table, forcing it below the lake floor, and consequently causing many lakes to dry up. Due to their inaccessibility, many of these lakes have remained relatively untouched by development, and only those lakes closest to the eastern edge of the desert have been utilized directly for either salt harvesting or tourism. This paper reports on research from both pristine and developed lakes, and reveals a higher TDS (20-50mS/cm compared to 0.5-5mS/cm) in the northern end relative to the southern end for undisturbed lakes. Water entering the southern end of the lakes is chemically identical to the local groundwater (TDS ~0.5mS/cm). This geographic difference in lake properties is remarkable, not only in terms of chemical variation, but also in terms of plant variety and abundance. Stable isotopes show a clear evaporation trend for these lakes, increasing from the southern tip, to the northern tip of individual lakes (-3 to -1‰ in the south, compared with 2-8‰ in the north, and -6 to -3‰ in the groundwater for δ2H). TDS likewise increases with increasing isotopic fractionation. The primary wind direction fluctuates from the southeast to the east, causing the movement of water from the southern end of the lake to the northern, and aiding in the evaporation. Once at the northern end of the lake, the water

  2. 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.

  3. Antibiotics and Antibiotic Resistance Genes in Sediment of Honghu Lake and East Dongting Lake, China.

    PubMed

    Yang, Yuyi; Cao, Xinhua; Lin, Hui; Wang, Jun

    2016-11-01

    Sediment is an ideal medium for the aggregation and dissemination of antibiotics and antibiotic resistance genes (ARGs). The levels of antibiotics and ARGs in Honghu Lake and East Dongting Lake of central China were investigated in this study. The concentrations of eight antibiotics (four sulfonamides and four tetracyclines) in Honghu Lake were in the range 90.00-437.43 μg kg(-1) (dry weight (dw)) with mean value of 278.21 μg kg(-1) dw, which was significantly higher than those in East Dongting Lake (60.02-321.04 μg kg(-1) dw, mean value of 195.70 μg kg(-1) dw). Among the tested three sulfonamide resistance genes (sul) and eight tetracycline resistance genes (tet), sul1, sul2, tetA, tetC, and tetM had 100 % detection frequency in sediment samples of East Dongting Lake, while only sul1, sul2, and tetC were observed in all samples of Honghu Lake. The relative abundance of sul2 was higher than that of sul1 at p < 0.05 level in both lakes. The relative abundance of tet genes in East Dongting Lake was in the following order: tetM > tetB > tetC > tetA. The relative abundance of sul1, sul2, and tetC in East Dongting Lake was significantly higher than those in Honghu Lake. The abundance of background bacteria may play an important role in the horizontal spread of sul2 and tetC genes in Honghu Lake and sul1 in East Dongting Lake, respectively. Redundancy analysis indicated that tetracyclines may play a more important role than sulfonamides in the abundance of sul1, sul2, and tetC gens in Honghu Lake and East Dongting Lake.

  4. Vertical profiles of water and sediment denitrifiers in two plateau freshwater lakes.

    PubMed

    Mao, Guozhu; Chen, Ling; Yang, Yuyin; Wu, Zhen; Tong, Tianli; Liu, Yong; Xie, Shuguang

    2017-04-01

    The present study investigated the abundance, richness, diversity, and community composition of denitrifiers (based on nirS and nosZ genes) in the stratified water columns and sediments in eutrophic Dianchi Lake and mesotrophic Erhai Lake using quantitative PCR assay and high-throughput sequencing analysis. Both nirS- and nosZ denitrifiers were detected in waters of these two lakes. Surface water showed higher nosZ gene density than bottom water, and Dianchi Lake waters had larger nirS gene abundance than Erhai Lake waters. The abundance of sediment nirS- and nosZ denitrifiers in Dianchi Lake was larger than that in Erhai Lake. nirS richness and diversity and nosZ richness tended to increase with increasing sediment layer depth in both lakes. The distinct structure difference of sediment nirS- and nosZ denitrifier communities was found between in Dianchi Lake and Erhai Lake. These two lakes also differed greatly in water denitrifier community structure. Moreover, phylogenetic analysis indicated the presence of several different groups of nirS- or nosZ denitrifiers in both lakes. The novel nirS denitrifiers were abundant in both Dianchi Lake and Erhai Lake, while most of the obtained nosZ sequences could be affiliated with known genera.

  5. 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.

  6. Disappearing lakes in semiarid Northern China: drivers and environmental impact.

    PubMed

    Liu, Hongyan; Yin, Yi; Piao, Shilong; Zhao, Fengjun; Engels, Mike; Ciais, Philippe

    2013-01-01

    The widely distributed 241 lakes in the semiarid region of China bordering the Asian Gobi desert provide an irreplaceable environment for the region's human inhabitants, livestock, and wildlife. Using satellite imagery, we tracked the changing areas of lake water and freshwater/salty marshes during the last four decades and correlated observed changes with concurrent temperature and precipitation. On average, most of the lake size groups across different subregions showed a reduction in area from the 1970s to 2000s, particularly from the 1990s to 2000s (P < 0.05); 121 of the 241 lakes became fully desiccated at the end of the 2000s. Our results confirmed the prevalence of drought-induced lake shrinkage and desiccation at a regional scale, which has been sustained since the year 2000, and highlighted an accelerated shrinkage of individual lakes by human water use in the agriculture-dominated regions. Lake waters have become salinized, and freshwater marsh has been replaced by salty marsh, threatening the populations of endangered waterfowl species such as the red-crowned crane as well as the aquatic ecosystem. Although the dry lakebeds are a potential source of dust, the establishment of salty marsh on bare lake beds could have partially reduced dust release due to the increase in vegetation cover.

  7. Spatial identification of critical nutrient loads of large shallow lakes: Implications for Lake Taihu (China).

    PubMed

    Janssen, Annette B G; de Jager, Victor C L; Janse, Jan H; Kong, Xiangzhen; Liu, Sien; Ye, Qinghua; Mooij, Wolf M

    2017-08-01

    Ongoing eutrophication frequently causes toxic phytoplankton blooms. This induces huge worldwide challenges for drinking water quality, food security and public health. Of crucial importance in avoiding and reducing blooms is to determine the maximum nutrient load ecosystems can absorb, while remaining in a good ecological state. These so called critical nutrient loads for lakes depend on the shape of the load-response curve. Due to spatial variation within lakes, load-response curves and therefore critical nutrient loads could vary throughout the lake. In this study we determine spatial patterns in critical nutrient loads for Lake Taihu (China) with a novel modelling approach called Spatial Ecosystem Bifurcation Analysis (SEBA). SEBA evaluates the impact of the lake's total external nutrient load on the local lake dynamics, resulting in a map of critical nutrient loads for different locations throughout the lake. Our analysis shows that the largest part of Lake Taihu follows a nonlinear load-response curve without hysteresis. The corresponding critical nutrient loads vary within the lake and depend on management goals, i.e. the maximum allowable chlorophyll concentration. According to our model, total nutrient loads need to be more than halved to reach chlorophyll-a concentrations of 30-40 μg L(-1) in most sections of the lake. To prevent phytoplankton blooms with 20 μg L(-1) chlorophyll-a throughout Lake Taihu, both phosphorus and nitrogen loads need a nearly 90% reduction. We conclude that our approach is of great value to determine critical nutrient loads of lake ecosystems such as Taihu and likely of spatially heterogeneous ecosystems in general. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Internal cycling, not external loading, decides the nutrient limitation in eutrophic lake: A dynamic model with temporal Bayesian hierarchical inference.

    PubMed

    Wu, Zhen; Liu, Yong; Liang, Zhongyao; Wu, Sifeng; Guo, Huaicheng

    2017-06-01

    Lake eutrophication is associated with excessive anthropogenic nutrients (mainly nitrogen (N) and phosphorus (P)) and unobserved internal nutrient cycling. Despite the advances in understanding the role of external loadings, the contribution of internal nutrient cycling is still an open question. A dynamic mass-balance model was developed to simulate and measure the contributions of internal cycling and external loading. It was based on the temporal Bayesian Hierarchical Framework (BHM), where we explored the seasonal patterns in the dynamics of nutrient cycling processes and the limitation of N and P on phytoplankton growth in hyper-eutrophic Lake Dianchi, China. The dynamic patterns of the five state variables (Chla, TP, ammonia, nitrate and organic N) were simulated based on the model. Five parameters (algae growth rate, sediment exchange rate of N and P, nitrification rate and denitrification rate) were estimated based on BHM. The model provided a good fit to observations. Our model results highlighted the role of internal cycling of N and P in Lake Dianchi. The internal cycling processes contributed more than external loading to the N and P changes in the water column. Further insights into the nutrient limitation analysis indicated that the sediment exchange of P determined the P limitation. Allowing for the contribution of denitrification to N removal, N was the more limiting nutrient in most of the time, however, P was the more important nutrient for eutrophication management. For Lake Dianchi, it would not be possible to recover solely by reducing the external watershed nutrient load; the mechanisms of internal cycling should also be considered as an approach to inhibit the release of sediments and to enhance denitrification. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Methane distribution and transportation in Lake Chaohu: a shallow eutrophic lake in Eastern China

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Shen, Q.

    2016-12-01

    Global warming and eutrophication are two world widely concerned environmental problems. Methane is the second important greenhouse gas, and lake has been proven as a quite important natural source of methane emission. More methane may emit from eutrophic lake due to the higher organic matter deposition in the lake sediment. Lake Chaohu is a large and shallow eutrophic lake in eastern China (N31°25' 31°43', E117°16' 117°05'), with an area of 770 km2 and a mean depth of 2.7 m. To examine methane distribution and transportation in this eutrophic lake, field study across different seasons was carried out with 20 study sites in the lake. Samples from the different water and sediment depth was collected using headspace bottle, and methane content was measured by gas chromatography using a flame ionization detector. The potential methane production in the sediment was examined by an indoor incubation experiment. Methane flux from sediment to the overlying water was calculated by Fick's law, and methane emission from surface to the air was calculated at the same time. The results indicates that more methane accumulated in the water of northwestern bay in this lake, and higher methane release rates was also found at this area. Methane increases gradually with depth in the top 10 cm in sediment cores, then it almost keeps at constant state in the deeper sediment. In the sediment from northwestern bay, more methane content and the higher potential methane production was found compared to the sediment from the east area of this lake.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. Interaction of hydrological regime and vegetation in a seasonally flooded lake wetland (Poyang Lake) in China

    NASA Astrophysics Data System (ADS)

    Zhang, Qi

    2017-04-01

    Hydrological regime has been widely recognized as one of the major forces determining vegetation distribution in seasonally flooded wetlands. To explore the influences of hydrological conditions on the spatial distribution of wetland vegetation, an experimental transect in Poyang Lake wetland, the largest freshwater lake in China, was selected as a study area. In-situ high time frequency observations of climate, soil moisture, groundwater level and surface water level were simultaneously conducted. Vegetation was sampled periodically to obtain species composition, diversity and biomass. Results show that significant hydrological gradient exists along the experimental transect. Both groundwater level and soil moisture demonstrate high correlation with the distribution of different communities of vegetation. Above- and belowground biomass present Gaussian models along the gradient of groundwater depth in growing seasons. It was found that the optimal average groundwater depths for above- and belowground biomass are 0.8 m and 0.5 m, respectively. Numerical simulations using HYDRUS-1D further indicated that the groundwater depths had significant influences on the water usage by vegetation, which suggested the high dependence of wetland vegetation on groundwater, even in a wet climate zone such as Poyang Lake. The study revealed new knowledge on the interaction of hydrological regime and wetland vegetation, and provided scientific support for an integrated management of balancing wetland ecology and water resources development in Poyang Lake, and other lake floodplain wetlands, with strong human interferences.

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Temporal and Spatial Dynamics of Archaeal Communities in Two Freshwater Lakes at Different Trophic Status.

    PubMed

    Yang, Yuyin; Dai, Yu; Wu, Zhen; Xie, Shuguang; Liu, Yong

    2016-01-01

    In either eutrophic Dianchi Lake or mesotrophic Erhai Lake, the abundance, diversity, and structure of archaeaplankton communities in spring were different from those in summer. In summer, archaeaplankton abundance generally decreased in Dianchi Lake but increased in Erhai Lake, while archaeaplankton diversity increased in both lakes. These two lakes had distinct archaeaplankton community structure. Archaeaplankton abundance was influenced by organic content, while trophic status determined archaeaplankton diversity and structure. Moreover, in summer, lake sediment archaeal abundance considerably decreased. Sediment archaeal abundance showed a remarkable spatial change in spring but only a slight one in summer. The evident spatial change of sediment archaeal diversity occurred in both seasons. In Dianchi Lake, sediment archaeal community structure in summer was remarkably different from that in spring. Compared to Erhai Lake, Dianchi Lake had relatively high sediment archaeal abundance but low diversity. These two lakes differed remarkably in sediment archaeal community structure. Trophic status determined sediment archaeal abundance, diversity and structure. Archaeal diversity in sediment was much higher than that in water. Water and sediment habitats differed greatly in archaeal community structure. Euryarchaeota predominated in water column, but showed much lower proportion in sediment. Bathyarchaeota was an important component of sediment archaeal community.

  4. Temporal and Spatial Dynamics of Archaeal Communities in Two Freshwater Lakes at Different Trophic Status

    PubMed Central

    Yang, Yuyin; Dai, Yu; Wu, Zhen; Xie, Shuguang; Liu, Yong

    2016-01-01

    In either eutrophic Dianchi Lake or mesotrophic Erhai Lake, the abundance, diversity, and structure of archaeaplankton communities in spring were different from those in summer. In summer, archaeaplankton abundance generally decreased in Dianchi Lake but increased in Erhai Lake, while archaeaplankton diversity increased in both lakes. These two lakes had distinct archaeaplankton community structure. Archaeaplankton abundance was influenced by organic content, while trophic status determined archaeaplankton diversity and structure. Moreover, in summer, lake sediment archaeal abundance considerably decreased. Sediment archaeal abundance showed a remarkable spatial change in spring but only a slight one in summer. The evident spatial change of sediment archaeal diversity occurred in both seasons. In Dianchi Lake, sediment archaeal community structure in summer was remarkably different from that in spring. Compared to Erhai Lake, Dianchi Lake had relatively high sediment archaeal abundance but low diversity. These two lakes differed remarkably in sediment archaeal community structure. Trophic status determined sediment archaeal abundance, diversity and structure. Archaeal diversity in sediment was much higher than that in water. Water and sediment habitats differed greatly in archaeal community structure. Euryarchaeota predominated in water column, but showed much lower proportion in sediment. Bathyarchaeota was an important component of sediment archaeal community. PMID:27065997

  5. Microbial biogeography of six salt lakes in Inner Mongolia, China, and a salt lake in Argentina.

    PubMed

    Pagaling, Eulyn; Wang, Huanzhi; Venables, Madeleine; Wallace, Andrew; Grant, William D; Cowan, Don A; Jones, Brian E; Ma, Yanhe; Ventosa, Antonio; Heaphy, Shaun

    2009-09-01

    We used cultivation-independent methods to investigate the prokaryotic biogeography of the water column in six salt lakes in Inner Mongolia, China, and a salt lake in Argentina. These lakes had different salt compositions and pH values and were at variable geographic distances, on both local and intercontinental scales, which allowed us to explore the microbial community composition within the context of both contemporary environmental conditions and geographic distance. Fourteen 16S rRNA gene clone libraries were constructed, and over 200 16S rRNA gene sequences were obtained. These sequences were used to construct biotic similarity matrices, which were used in combination with environmental similarity matrices and a distance matrix in the Mantel test to discover which factors significantly influenced biotic similarity. We showed that archaeal biogeography was influenced by contemporary environmental factors alone (Na+, CO3(2-), and HCO3(-) ion concentrations; pH; and temperature). Bacterial biogeography was influenced both by contemporary environmental factors (Na+, Mg2+, and HCO3(-) ion concentrations and pH) and by geographic distance.

  6. Surface Water Quality Monitoring Site Optimization for Poyang Lake, the Largest Freshwater Lake in China

    PubMed Central

    Wang, Hua; Wu, Mengan; Deng, Yanqing; Tang, Chunyan; Yang, Rui

    2014-01-01

    In this paper, we propose a coupled method to optimize the surface water quality monitoring sites for a huge freshwater lake based on field investigations, mathematical analysis, and numerical simulation tests. Poyang Lake, the largest freshwater lake in China, was selected as the research area. Based on the field investigated water quality data in the 5 years from 2008 to 2012, the water quality inter-annual variation coefficients at all the present sites and the water quality correlation coefficients between adjacent sites were calculated and analyzed to present an optimization scheme. A 2-D unsteady water quality model was established to get the corresponding water quality data at the optimized monitoring sites, which were needed for the rationality test on the optimized monitoring network. We found that: (1) the water quality of Piaoshan (No. 10) fluctuated most distinguishably and the inter-annual variation coefficient of NH3-N and TP could reach 99.77% and 73.92%, respectively. The four studied indexes were all closely related at Piaoshan (No. 10) and Tangyin (No. 11), and the correlation coefficients of COD and NH3-N could reach 0.91 and 0.94 separately. (2) It was suggested that the present site No. 10 be removed to avoid repeatability, and it was suggested that the three sites of Changling, Huzhong, and Nanjiang be added to improve the representativeness of the monitoring sites. (3) According to the rationality analysis, the 21 optimized water quality monitoring sites could scientifically replace the primary network, and the new monitoring network could better reflect the water quality of the whole lake. PMID:25407419

  7. 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.

  8. Characteristics of dissolved organic phosphorus inputs to freshwater lakes: A case study of Lake Erhai, southwest China.

    PubMed

    Ji, Ningning; Wang, Shengrui; Zhang, Li

    2017-12-01

    In this study, we made the first estimate of the annual dissolved organic phosphorus (DOP) load to Lake Erhai, a typical mesotrophic-eutrophic lake in China. We also evaluated what proportion of DOP was bioavailable using enzymatically hydrolyzable phosphorus (EHP), and further assessed the potential impacts of DOP on lake water quality. We estimated that the annual DOP load into Lake Erhai accounted for nearly 50% of total dissolved phosphorus, while EHP accounted for about 30% of the bioavailable phosphorus (BAP) pool. The DOP load increased and accounted for a greater proportion of total dissolved phosphorus and BAP loads during the wet season, and helped maintain algal blooms. Inflowing rivers were the main source of DOP with high bioavailability to Lake Erhai, especially in the wet season. The EHP concentrations of the inflowing rivers were positively correlated with algal biomass. The observation suggests that, as a significant source of BAP, the contribution of the DOP load to eutrophication of the lake should not be ignored, especially given the low soluble reactive phosphorus concentrations in the lake water during the algal biomass period. Information on the contributions from different pollution sources is needed to support the development of effective P pollution control strategies. Short-term strategies to protect Lake Erhai include better management of the inflowing rivers, especially in the northern part during the wet season, while, over the long-term, strategies to decrease P release from lake sediments should be considered. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. What caused the decline of China's largest freshwater lake? Attribution analysis on Poyang Lake water level variations in recent years

    NASA Astrophysics Data System (ADS)

    Ye, Xuchun; Xu, Chong-Yu; Zhang, Qi

    2017-04-01

    In recent years, dramatic decline of water level of the Poyang Lake, China's largest freshwater lake, has raised wide concerns about the water security and wetland ecosystem. This remarkable hydrological change coincided with several factors like the initial operation of the Three Gorges Dam (TGD) in 2003, the big change of lake bottom topography due to extensive sand mining in the lake since 2000, and also climate change and other human activities in the Yangtze River basin may add to this complexity. Questions raised to what extent that the lake hydrological changes is caused by climate change and/or human activities. In this study, quantitative assessment was conducted to clarify the magnitude and mechanism of specific influencing factors on recent lake decline (2003-2014), with reference to the period of 1980-1999. The attempts were achieved through the reconstruction of lake water level scenarios by the framework of neural network. Major result indicates that the effect of lake bottom topography change due to sand mining activities has became the dominant factor for the recent lake decline, especially in winter season with low water level. However, the effect of TGD regulation shows strong seasonal features, its effect can accounts for 33%-42% of the average water level decline across the lake during the impoundment period of September-October. In addition, the effect of climate change and other human activities over the Yangtze River basin needs to be highly addressed, which is particularly prominent on reducing lake water level during the summer flood season and autumn recession period. The result also revealed that due to different mechanism, the responses of the lake water level to the three influencing factors are not consistent and show great spatial and temporal differences.

  10. 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.

  11. 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.

  12. How Do the Chinese Perceive Ecological Risk in Freshwater Lakes?

    PubMed Central

    Huang, Lei; Han, Yuting; Zhou, Ying; Gutscher, Heinz; Bi, Jun

    2013-01-01

    In this study, we explore the potential contributions of a risk perception framework in understanding public perceptions of unstable ecosystems. In doing so, we characterize one type of common ecological risk– harmful algal blooms (HABs)–in four of the most seriously eutrophicated freshwater lakes in China. These lakes include Chaohu, Dianchi, Hongze, and Taihu, where a total of 2000 residents living near these sites were interviewed. Regional discrepancies existed in the pilot study regarding public perceptions of ecological changes and public concerns for ecological risk. Comparing HABs and other kinds of risks (earthquake, nuclear, and public traffic) through the psychometric paradigm method, Knowledge, Effect, and Trust were three key factors formulating the risk perception model. The results indicated that Knowledge and risk tolerance levels had significant negative correlations in the higher economic situation while correlations in the lower economic situation were significantly positive. Effect and risk tolerance levels had significant negative correlations in the high and middle education situation while correlations in the low education situation were close to zero or insignificant. For residents from Taihu with comparatively higher economic and educational levels, more investment in risk prevention measures and stronger policies are needed. And for residents from Hongze and Dianchi with comparatively low economic and educational levels, improvement of the government’s credibility (Trust) was the most important factor of risk tolerance, so efforts to eliminate ecological problems with the stepwise development of economic and educational levels should be implemented and gradually strengthened. In turn, this could prevent public discontent and ensure support for ecological protection policies. PMID:23671602

  13. How do the Chinese perceive ecological risk in freshwater lakes?

    PubMed

    Huang, Lei; Han, Yuting; Zhou, Ying; Gutscher, Heinz; Bi, Jun

    2013-01-01

    In this study, we explore the potential contributions of a risk perception framework in understanding public perceptions of unstable ecosystems. In doing so, we characterize one type of common ecological risk- harmful algal blooms (HABs)-in four of the most seriously eutrophicated freshwater lakes in China. These lakes include Chaohu, Dianchi, Hongze, and Taihu, where a total of 2000 residents living near these sites were interviewed. Regional discrepancies existed in the pilot study regarding public perceptions of ecological changes and public concerns for ecological risk. Comparing HABs and other kinds of risks (earthquake, nuclear, and public traffic) through the psychometric paradigm method, Knowledge, Effect, and Trust were three key factors formulating the risk perception model. The results indicated that Knowledge and risk tolerance levels had significant negative correlations in the higher economic situation while correlations in the lower economic situation were significantly positive. Effect and risk tolerance levels had significant negative correlations in the high and middle education situation while correlations in the low education situation were close to zero or insignificant. For residents from Taihu with comparatively higher economic and educational levels, more investment in risk prevention measures and stronger policies are needed. And for residents from Hongze and Dianchi with comparatively low economic and educational levels, improvement of the government's credibility (Trust) was the most important factor of risk tolerance, so efforts to eliminate ecological problems with the stepwise development of economic and educational levels should be implemented and gradually strengthened. In turn, this could prevent public discontent and ensure support for ecological protection policies.

  14. 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.

  15. 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.

  16. The current status of heavy metal in lake sediments from China: Pollution and ecological risk assessment.

    PubMed

    Xu, Yongfeng; Wu, Yi; Han, Jiangang; Li, Pingping

    2017-07-01

    Heavy metal contamination in lake sediments is a serious problem, particularly in developing countries such as China. To evaluate heavy metal pollution and risk of contamination in lake sediments on a national scale in China, we collated available data in the literature of the last 10 years on lake sediments polluted with heavy metals from 24 provinces in China. Based on these data, we used sediment quality guidelines, geoaccumulation index, and potential ecological risk index to assess potential ecological risk levels. The results showed that approximately 20.6% of the lakes studied exceeded grade II level in Chinese soil quality standards for As, 31.3% for Cd, 4.6% for Cu, 20.8% for Ni, 2.8% for Zn, and 11.1% for Hg, respectively. Besides, the mean concentrations for As in 10.3% of lakes, Hg in 11.9% of lakes, and Ni in 31.3% of lakes surpassed the probable effect level. The potential ecological risk for toxic metals decreased in the order of Cd > Hg > As > Cu > Pb > Ni > Cr > Zn, and there were 21.8% of the lakes studied in the state of moderate risk, 10.9% in high risk, and 12.7% in very high risk. It can be concluded that Chinese lake sediments are polluted by heavy metals to varying degrees. In order to provide key management targets for relevant administrative agencies, based on the results of the pollution and ecological risk assessments, Cd, Hg, As, Cu, and Ni were selected as the priority control heavy metals, and the eastern coastal provinces and Hunan province were selected as the priority control provinces. This article, therefore, provides a comprehensive assessment of heavy metal pollution in lake sediments in China, while providing a reference for the development of lake sediment quality standards.

  17. Characterization of organic phosphorus in lake sediments by sequential fractionation and enzymatic hydrolysis

    USDA-ARS?s Scientific Manuscript database

    Knowledge of the phosphorus (P) fractions and their bioavailability in sediments is fundamental for understanding the biogeochemical process of P cycle and its role on eutrophication in the lake ecosystems. In this study, 18 surface sediments samples were collected from Dianchi Lake, an eutrophic la...

  18. 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.

  19. Dramatic inundation changes of China's two largest freshwater lakes linked to the Three Gorges Dam.

    PubMed

    Feng, Lian; Hu, Chuanmin; Chen, Xiaoling; Zhao, Xi

    2013-09-03

    Ever since its planning in the 1990s, the Three Gorges Dam (TGD) caused endless debate in China on its potential impacts on the environment and humans. However, to date, synoptic assessment of environmental changes and their potential linkage with the TGD is still lacking. Here, we combine remote sensing, meteorological, and hydrological observations to investigate the potential influence of the TGD on the downstream freshwater lakes. A 10 year Moderate Resolution Imaging Spectroradiometer (MODIS) time series from 2000 to 2009 revealed significantly decreasing trends (3.3 and 3.6%/year) in the inundation areas of the two largest freshwater lakes of China (Poyang Lake and Dongting Lake) downstream of the TGD since its impoundment in 2003, after which both relative humidity and surface runoff coefficient of the lakes' drainages also dropped dramatically. These environmental changes appear to be linked to the TGD.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. [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

  9. 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.

  10. 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.

  11. Hydroclimatological influences on recently increased droughts in China's largest freshwater lake

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Wu, G.

    2016-01-01

    Lake droughts are the consequence of climatic, hydrologic and anthropogenic influences. Quantification of droughts and estimation of the contributions from the individual factors are essential for understanding drought features and their causation structure. This is also important for policymakers to make effective adaption decisions, especially under changing climate. This study examines Poyang Lake, China's largest freshwater lake, which has been undergoing drastic hydrological alternation in the past decade. Standardized lake stage is used to identify and quantify the lake droughts, and hydroclimatic contributions are determined with a water budget analysis, in which absolute deficiency is defined in reference to normal hydrologic conditions. Our analyses demonstrate that in the past decade the lake droughts worsened in terms of duration, frequency, intensity and severity. Hydroclimatic contributions to each individual drought varied between droughts, and the overall contribution to the lake droughts in the past decade came from decreased inflow, increased outflow, and reduced precipitation and increased evapotranspiration in the lake region. The decreased inflow resulted mainly from reduced precipitation and less from increased evapotranspiration over the Poyang Lake basin. The increased outflow was attributable to the weakened blocking effects of the Yangtze River, which the Three Gorges Dam (TGD) established upstream. The TGD impoundments were not responsible for the increased number of drought events, but they may have intensified the droughts and changed the frequency of classified droughts. However, the TGD contribution is limited in comparison with hydroclimatic influences. Hence, the recently increased droughts were due to hydroclimatic effects, with a less important contribution from anthropogenic influences.

  12. 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.

  13. 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

  14. 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.

  15. Characterization of pharmaceutically active compounds in Dongting Lake, China: Occurrence, chiral profiling and environmental risk.

    PubMed

    Ma, Ruixue; Wang, Bin; Lu, Shaoyong; Zhang, Yizhe; Yin, Lina; Huang, Jun; Deng, Shubo; Wang, Yujue; Yu, Gang

    2016-07-01

    Twenty commonly used pharmaceuticals including eight chiral drugs were investigated in Dongting Lake, China. The contamination level was relatively low on a global scale. Twelve pharmaceuticals were identified. The most abundant compound was caffeine followed by diclofenac, DEET, mefenamic acid, fluoxetine, ibuprofen and carbamazepine with mean concentrations from 2.0 to 80.8ngL(-1). Concentrations between East and West Dongting Lake showed spatial difference, with the West Dongting Lake less polluted. The relatively high ratio of caffeine versus carbamazepine (over 50) may indicate there was possible direct discharge of domestic wastewater into the lake. This is the first study presenting a survey allowing for comprehensive analysis of multiclass achiral and chiral pharmaceuticals including beta-blockers, antidepressants and anti-inflammatory drugs in freshwater lake. The enantiomeric compositions presented racemic to weakly enantioselective, with the highest enantiomeric fraction (EF) of 0.63 for fluoxetine. Meanwhile, venlafaxine was identified and evaluated the environment risk in surface water in China for the first time. The results of risk assessment suggested that fluoxetine, venlafaxine and diclofenac acid might pose a significant risk to aquatic organisms in Dongting Lake. The resulting data will be useful to enrich the research of emerging pollutants in freshwater lake and stereochemistry for environment investigations. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. Within-lake heterogeneity of environmental factors structuring bacterial community composition in Lake Dongting, China.

    PubMed

    Niu, Yuan; Yu, Hui; Jiang, Xia

    2015-11-01

    Within-lake heterogeneity of bacterial community composition (BCC) was investigated in the large and shallow regulating Lake Dongting. Samples were collected at 13 sites located in different areas of the lake. PCR-denaturing gradient gel electrophoresis (DGGE) and redundancy analysis (RDA) were used for revealing spatial distribution of BCC and the relationships between BCC and environmental variables. The DGGE banding patterns revealed a remarkable spatial heterogeneity which was closely related to their geographical positions. RDA result demonstrated that TP and TN, as well as Secchi depth, were the three most influential factors, responsible for a major part of the observed variation in BCC. Total bacterial abundances were significantly higher in Eastern Dongting due to high TP and suspended solids. In conclusion, bacterial community diversity in Lake Dongting was mainly shaped by within-lake heterogeneity of nutrient and transparency.

  4. Effects of river-lake interactions in water and sediment on phosphorus in Dongting Lake, China.

    PubMed

    Tian, Zebin; Zheng, Binghui; Wang, Lijing; Li, Hong; Wang, Xing

    2017-08-22

    As a large river connected lake, Dongting Lake is influenced by anthropogenic activities and the discharge from its upstream tributaries in the lake basin and by the water recharge via a connection to the Yangtze River (YR) outside the basin. This makes the lake phosphorous cycle more complex than that in other disconnected lakes. Here, we calculated section fluxes and ran a hydrodynamic model to investigate the phosphorus (P) variations in response to the changing interactions in the water and sediment between the YR, four tributaries, and the lake. Results show that particulate P was the dominant form with a significant linear relationship with suspended sediment (r (2) = 0.906). The sediment input reduction from the YR through three water inlets, which is closely related to the Three Gorges Reservoir operation since 2003, led to a decrease in the total P (TP) concentration in the western Dongting Lake. However, the impact and range of this decrease were fairly limited. Compared with the limited effect of the YR, the raised TP flux from the Yuanjiang tributary controlled the TP concentration at the outlet of the western Dongting Lake. Apart from the influence of the YR and the tributaries, anthropogenic activities (sand dredging) in the eastern Dongting Lake also contributed to a high TP concentration around the S10 area through sediment resuspension. We suggest that, compared with the reduction in TP flux and sediment load from the connected Yangtze River outside the basin, the elements within the basin (increased TP input from tributaries and sand dredging) have a greater effect on the variations of TP in Dongting Lake.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Little impact of the Three Gorges Dam on recent decadal lake decline across China's Yangtze Plain

    NASA Astrophysics Data System (ADS)

    Wang, Jida; Sheng, Yongwei; Wada, Yoshihide

    2017-05-01

    The ubiquitous lakes across China's Yangtze Plain (YP) are indispensable freshwater resources sustaining ecosystems and socioeconomics for nearly half a billion people. Our recent survey revealed a widespread net decline in the total YP lake inundation area during 2000-2011 (a cumulative decrease of ˜10%), yet its mechanism remained contentious. Here we uncover the impacts of climate variability and anthropogenic activities including (i) Yangtze flow and sediment alterations by the Three Gorges Dam (TGD) and (ii) human water consumption in agricultural, industrial, and domestic sectors throughout the downstream Yangtze Basin. Results suggest that climate variability is the dominant driver of this decadal lake decline, whereas studied human activities, despite varying seasonal impacts that peak in fall, contribute marginal fraction (˜10-20% or less) to the interannual lake area decrease. Given that the TGD impacts on the total YP lake area and its seasonal variation are both under ˜5%, we also dismiss the speculation that the TGD might be responsible for evident downstream climate change by altering lake surface extent and thus open water evaporation. Nevertheless, anthropogenic impacts exhibited a strengthening trend during the past decade. Although the TGD has reached its full-capacity water regulation, the negative impacts of human water consumption and TGD-induced net channel erosion, which are already comparable to that of TGD's flow regulation, may continue to grow as crucial anthropogenic factors to future YP lake conservation.

  11. Water transparency distribution under varied currents in the largest river-connected lake of China.

    PubMed

    Wang, Hua; Zhao, Yijun; Zhang, Zhizhang; Pang, Yong; Liang, Dongfang

    2017-01-01

    Water transparency is an important ecological indicator for shallow lakes. The largest shallow lake, Poyang Lake, as well as the most typical river-connected lake in China was selected as the research area. In view of the complicated water-sediment conditions induced by its frequent water exchange with external rivers, the dominant factors driving water transparency were determined against the field investigated data from 2003 to 2013 and a specific driving function was established. A numerical model coupling suspended sediment, Chl-a and chemical oxygen demand was developed and validated, and the spatial water transparency distributions under three typical current structures in Poyang Lake, Gravity-style, Jacking-style and Backflow-style, were quantitatively estimated. The following results stood out: water transparency in the lake varied distinctly with the current status; Backflow-style current was basically characterized by the lowest water transparency, while that under Jacking-style was the highest due to the lower sediment carrying capacity. In some outlying regions in the lake, where the water current is hardly influenced by the mainstream, the water transparency was always kept at a stable level.

  12. Comparison of lake records for climate reconstructions: A case study from Hala Lake, northern Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Wuennemann, B.

    2012-12-01

    Sediment cores from a lake are often interpreted in light of modern limnological and environmental conditions to infer past climate and hydrological conditions in a region. Records from the Tibetan Plateau and adjacent areas display a heterogeneous picture through space and time. The saline Hala Lake, located in the Qilian Mountains, Qinghai Province, China, at 4078 m a.s.l. was selected to prove the applicability of a selected single sediment core for a consistent inference of past hydrological and climate conditions. Based on nine sediment cores obtained from different locations and water depth, sedimentation patterns and depositional conditions within the lake were investigated in detail. Two long cores H7 and H8 from the center of the lake (65 m water depth) and from the western nearshore location (20 m water depth) were compared by means of sedimentary composition, minerals and geochemical data (X-ray diffraction, X-ray fluorescence, loss-on-ignition, and by CNS analyzer). The respective age model was based on seventeen AMS radiocarbon dates, indicating a negligible reservoir error for sediments from the lake center and approximately 1,000 years error for the near-shoreline sediments. Six cores from the littoral zone revealed a sedimentary succession from sand and silty clay to laminated clay at the southern side of the lake. Undisturbed finely laminated sediments were found from 15 m water depth down to the deepest part. Core H5 (2.5 m length) from 31 m water depth yielded abundant green algal mats mixed with clayey lake deposits. Algae occurred between 25 and 32 m water depth and influenced the dissolved oxygen content of the stratified lake. The comparison of cores H7 and H8 yielded prominent mismatches for different time periods, which may, in part, attributed to lake internal processes independent of climatic influence. We thus conclude that data from a single sediment core may lead to different climate inferences. Common shifts among proxy data, however

  13. [Seasonal Variability of Greenhouse Gas Emissions in the Urban Lakes in Changchun, China].

    PubMed

    Wen, Zhi-dan; Song, Kai-shan; Zhao, Ying; Shao, Tian-tian; Li, Si-jia

    2016-01-15

    The partial pressures of carbon dioxide p(CO2) and methane p(CH4) in the surface water of seven urban lakes in Changchun city, China (Nan Lake, Bei Lake, Yanming Lake, Shengli, Dilisuo, Changchun, Tianjia) , have been studied in both summer and autumn related to the environment and water quality parameters. The results indicated that both in summer and autumn, CH4 of seven lakes was all supersaturated, and CO2 was all supersaturated except in Nan lake and Shengli lake. For either p( C02) or p( CH4), there was a significant difference among different urban lakes (P < 0.05), and there was almost no obvious difference in the same lake between summer and autumn. The gas flux also had a significant difference among different urban lakes (P <0. 05). Except for Nan Lake and Shengli, all other lakes were the sources of atmospheric CO2 and CH4 both in summer and fall, and the discharge of CO2 to atmosphere by lakes was more than that of CH4. According to the correlation analysis, there was a significant negative relationship between p(CO2, CH4) and sunshine duration in summer (r p(CO2) = -0.48, P <0. 05; rp(CH4) = -0.63, P < 0.01). The sunshine duration could affect the concentrations of CO2 and dissolved oxygen in the water by influencing the photosynthesis of aquatic plants. There was also a significant negative relationship between p(CH4) and precipitation in summer (r p(CH4) = 0.44, P < 0.05), and between p (CO2) and air temperature in autumn (r p(cO2) = -0.39, P < 0.05). The correlation analysis between water quality parameters and p(CO2, CH4) showed that both p(CO2) and p(CH4) were negatively correlated with pH (r(Co2) = -0.51, r P(C4) = -0.82, P < 0.01), while they were positively correlated with salinity (r p(CO2) = 0.38, P < 0.05; r p(CH4) = 0.75, P < 0.01). The results suggested that the levels of nutrients in these urban lakes, which were related to the phytoplankton biomass, were not the main influencing factors for p(CO2) in surface water, and sunshine duration

  14. Change in Microbial Community with Salinity in the Sediment of Lake Chaka, a hypersaline lake in Northwestern China

    NASA Astrophysics Data System (ADS)

    Jiang, H.; Yu, B.; Dong, H.; Li, Y.; Zhang, C.

    2005-12-01

    Lake Chaka (36°18'-36°45'N,99°02'-99°12'E), 3800 m above sea level, is located on the Qinghai-Tibetan Plateau, northwestern China, where semi-arid continental climate dominates. The basin of Lake Chaka is about 80 km long and 30 km wide. Strong evaporation and little precipitation (2264 mm evaporation versus 224 mm rainfall/year) in this area have resulted in a nearly dry lake and high salinity (21%). The pH of lake water is 7.4. In November 2004, a sediment core of 10 m in length was collected in Lake Chaka. This sediment core covered a salinity gradient from fresh water at the bottom of the core (10-m depth) to near salt saturation at the surface. Mineralogy also changed with depth, ranging from mud-fine sands at the bottom to mirabilite (Na2SO4) and gypsum in the middle to halite near the top. The biomass determined by acridine orange direct count (AODC) in the sediment core was about 108 cells per gram of wet sample from the bottom to the top. Microbial diversity and community structure as determined by phospholipid fatty acid analysis (PFLA) and 16S rRNA gene analyses in the sediment systematically changed with increasing salinity. Overall, microbial diversity decreased with increasing salinity. At the bottom, freshwater microorganisms are dominant. Near the top of the core, halophilic bacteria and archaea are predominant microorganisms. This systematic change in microbial diversity and community structure is a result of microbial response to progressive increase in salinity in the last 50,000 years.

  15. 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.

  16. 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.

  17. 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.

  18. The characteristic of the Younger Dryas Event in Bilut Lake, Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Hsiao, H.; Song, S.; Chen, H.; Wang, Y.; Lee, T.

    2010-12-01

    To investigate the region which affected by Younger Dryas Event, we collect sediments of the lakes from Inner Mongolia of China. In general, sediments of lakes and sea are considered as a good material to study climate change because they could record continuously the information about the change of environment for long time. Inner Mongolia is located at the central part of the Asian continent, where its climate is controlled predominantly by the interaction between the East Asian monsoons and Westerly. At least 494 lakes have been recognized from the literature and aerial images that provide good materials for studying the climate changes occurred in this area. The Bilut Lake (43°25'12.0'' N, 113°46'32.5'' E) is located in the center of Inner Mongolia, and it is the farming-grazing transitional zone in northern China. It is considered as a sensitive response for the climate change, so we drilled and analyzed the lake sediments here. The retrieved core from this lake was 751 cm in length which covered the age ranging from 9.5 to 13 cal. ka, and the average sedimentation rate was estimated as 0.167cm/yr. The lacustrine sediments are composed of gray-green mud with interbedded silts in bottom, and black muds are distributed randomly in the core. The X-ray diffraction (XRD) analyses show that the mineral assemblages are mainly constituted with quartz, feldspar, illite, aragonite, dolomite and some saline minerals. The presence of aragonite may imply warm and dry climate in 10.2 to 10.7 cal. ka and 12.6 to 12.7 cal. ka. The presence of dolomite also suggests dry climate in 11 to 12 cal. ka. The investigation of mineralogical results will be combined with major element analyses and mineral-magnetism measurements further and discuss the characteristic of the YD event in the North China.

  19. Moderate Resolution Imaging Spectroradiometer (MODIS) observations of cyanobacteria blooms in Taihu Lake, China

    NASA Astrophysics Data System (ADS)

    Hu, Chuanmin; Lee, Zhongping; Ma, Ronghua; Yu, Kun; Li, Daqiu; Shang, Shaoling

    2010-04-01

    A novel approach was used with data from the Moderate Resolution Imaging Spectroradiometer (MODIS) to characterize the intense blooms of cyanobacteria (primarily Microcystis aeruginosa) in Taihu Lake, China's third largest freshwater lake. The approach involves first deriving a floating algae index (FAI) based on the medium-resolution (250 and 500 m) MODIS reflectance data at 645, 859, and 1240 nm after correction of the ozone/gaseous absorption and Rayleigh scattering effects and then objectively determining the FAI threshold value (-0.004) to separate the bloom and nonbloom waters. By definition, the term "bloom" or "floating algae" refers to bloom where cyanobacteria form floating scums on the water surface. The 9 year MODIS time series data showed bloom characteristics (annual occurrence frequency, timing, and duration) between 2000 and 2008. Assuming 25% area coverage as a gauge for significance, significant bloom events rarely occurred between 2000 and 2004 for the entire lake (excluding East Bay) or several lake segments (Northwest Lake, Southwest Lake, and Central Lake). In most lake segments, the annual frequency of significant blooms increased from 2000-2004 to 2006-2008, when they started earlier and had a longer duration. The year 2007 showed unique bloom characteristics due to conditions highly favorable for bloom development and proliferation. The results suggest that the long-term bloom patterns are driven by both nutrients and climatic factors. The multiyear series of consistent MODIS FAI data products provide baseline information to monitor the lake's bloom condition, one of the critical water quality indicators, on a weekly basis, as well as to evaluate its future water quality trends.

  20. Riverine inputs and source tracing of perfluoroalkyl substances (PFASs) in Taihu Lake, China.

    PubMed

    Ma, Xinxin; Shan, Guoqiang; Chen, Meng; Zhao, Jinyu; Zhu, Lingyan

    2017-08-25

    The occurrence, riverine inputs and sources of perfluoroalkyl substances (PFASs) in Taihu Lake, one of the largest lakes in China, were investigated by measuring PFASs including the isomers of perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA) and perfluorohexanesulfonate (PFHxS) in the Lake and its main flow-in rivers. It was found that PFHxS, instead of PFOS or PFOA, was predominant both in the Lake and rivers (45.9-351ng/L), reflecting increasing demand of PFHxS in recent years. The riverine flux of PFASs into the Lake was estimated to be 1255kg/year. The percentage of linear (n-) PFOS and the ratio of 3+5m-/1m-PFOS were combined to indicate indirect source due to biodegradation of PFOS-precursors. The percentage order of n-PFOS was: the Lake (48.7%)Lake (11.9)>the rivers (8.99)>ECF (electrochemical fluorination) product (6.76). These suggested that degradation of PFOS-precursors made distinct contribution to PFOS load in the waters, particularly in the Lake. The Lake and river waters had a consistent proportion of n-PFHxS (89.0%), which was slightly lower than the ECF product (96.0%), indicating it was mainly due to the release from production and application of PFHxS as an active ingredient. Copyright © 2017. Published by Elsevier B.V.

  1. 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.

  2. 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

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

    PubMed

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

    2016-11-07

    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.

  4. 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.

  5. 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.

  6. 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.

  7. Microbial Biogeography of Six Salt Lakes in Inner Mongolia, China, and a Salt Lake in Argentina ▿ †

    PubMed Central

    Pagaling, Eulyn; Wang, Huanzhi; Venables, Madeleine; Wallace, Andrew; Grant, William D.; Cowan, Don A.; Jones, Brian E.; Ma, Yanhe; Ventosa, Antonio; Heaphy, Shaun

    2009-01-01

    We used cultivation-independent methods to investigate the prokaryotic biogeography of the water column in six salt lakes in Inner Mongolia, China, and a salt lake in Argentina. These lakes had different salt compositions and pH values and were at variable geographic distances, on both local and intercontinental scales, which allowed us to explore the microbial community composition within the context of both contemporary environmental conditions and geographic distance. Fourteen 16S rRNA gene clone libraries were constructed, and over 200 16S rRNA gene sequences were obtained. These sequences were used to construct biotic similarity matrices, which were used in combination with environmental similarity matrices and a distance matrix in the Mantel test to discover which factors significantly influenced biotic similarity. We showed that archaeal biogeography was influenced by contemporary environmental factors alone (Na+, CO32−, and HCO3− ion concentrations; pH; and temperature). Bacterial biogeography was influenced both by contemporary environmental factors (Na+, Mg2+, and HCO3− ion concentrations and pH) and by geographic distance. PMID:19648369

  8. 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.

  9. Sedimentary Evidence of Environmental Degradation in Sanliqi Lake, Daye City (A Typical Mining City, Central China).

    PubMed

    Zeng, Linghan; Ning, Dongliang; Xu, Lei; Mao, Xin; Chen, Xu

    2015-09-01

    To reconstruct the history of environmental degradation in Sanliqi Lake (Daye City, central China), multiple proxies were analyzed in a sedimentary core which was dated using (137)Cs and spheroidal carbonaceous particles (SCPs). The results show that Sanliqi Lake has experienced serious degradation during the past 60 years, resulting from a large influx of metals and nutrients. Expansion of agricultural and industrial activities between 1945 and 1993 enhanced nutrient and metal enrichment, indicated by increases in metals, SCPs, magnetic susceptibility, total phosphorus, total nitrogen and total organic carbon. Further enrichment of Zn, Cd, Ni and Cr after 1993 was linked to a recent intensification of mining activities. Decreases in Cu and Pb after 2006 probably resulted from recent environmental remediation. This study verified the coupling between lake sediment pollution and human activities in Daye City during the past 60 years. The reconstructed history of lake pollution can provide reference information for continued restoration of Sanliqi Lake and other similar heavily polluted lakes in the developing regions.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Mapping and Monitoring the 2010 Flood Event in China: Case of Poyang Lake

    NASA Astrophysics Data System (ADS)

    Huber, C.; Uribe, C.; Lai, X.; Huang, S.; Chen, X.; Yesou, H.

    2013-01-01

    During the summer 2010, China suffered of extreme events, no so far from the dramatic 1998 ones. Major lakes such as Dongting and Poyang and major Chinese rivers overflow all around the country. Upstream of the Poyang Lake, the Fuhe River flooded the Luozhen Township of Fuzhou City. A breach occurred on Changkai dike and forced to evacuate 1,32 million of people on the 21st and again on the 23th of June 2010. In Poyang Lake, this flood situation followed a drought episode during the winter 2009-2010 ; and after, this flood event involved a stagnation of water longer than usual. Thanks to the DRAGON II Wetland project, the ESA accorded a special authorization of programming ENVISAT WSM images on a high revisiting schema, every 3 to 5 days, for all 2010 summer period.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. Enhancement of sediment phosphorus release during a tunnel construction across an urban lake (Lake Donghu, China).

    PubMed

    Wang, Siyang; Li, Hui; Xiao, Jian; Zhou, Yiyong; Song, Chunlei; Bi, Yonghong; Cao, Xiuyun

    2016-09-01

    Tunnel construction in watershed area of urban lakes would accelerate eutrophication by inputting nutrients into them, while mechanisms underlying the internal phosphorus cycling as affected by construction events are scarcely studied. Focusing on two main pathways of phosphorus releasing from sediment (enzymatic mineralization and anaerobic desorption), spatial and temporal variations in phosphorus fractionation, and activities of extracellular enzymes (alkaline phosphatase, β-1,4-glucosidase, leucine aminopeptidase, dehydrogenase, lipase) in sediment were examined, together with relevant parameters in interstitial and surface waters in a Chinese urban lake (Lake Donghu) where a subaqueous tunnel was constructed across it from October 2013 to July 2014. Higher alkaline phosphatase activity (APA) indicated phosphorus deficiency for phytoplankton, as illustrated by a significantly negative relationship between APA and concentration of dissolved total phosphorus (DTP). Noticeably, in the construction area, APAs in both sediment and surface water were significantly lower than those in other relevant basins, suggesting a phosphorus supply from some sources in this area. In parallel, its sediment gave the significantly lower iron-bound phosphorus (Fe(OOH)∼P) content, coupled with significantly higher ratio of iron (II) to total iron content (Fe(2+)/TFe) and dehydrogenase activities (DHA). Contrastingly, difference in the activities of sediment hydrolases was not significant between the construction area and other basins studied. Thus, in the construction area, subsidy of bioavailable phosphorus from sediment to surface water was attributable to the anaerobic desorption of Fe(OOH)∼P rather than enzymatic mineralization. Finally, there existed a significantly positive relationship between chlorophyll a concentration in surface water and Fe(OOH)∼P content in sediment. In short, construction activities within lakes may interrupt cycling patterns of phosphorus across

  3. 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.

  4. 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.

  5. An integrated system dynamics model developed for managing lake water quality at the watershed scale.

    PubMed

    Liu, Hui; Benoit, Gaboury; Liu, Tao; Liu, Yong; Guo, Huaicheng

    2015-05-15

    A reliable system simulation to relate socioeconomic development with water environment and to comprehensively represent a watershed's dynamic features is important. In this study, after identifying lake watershed system processes, we developed a system dynamics modeling framework for managing lake water quality at the watershed scale. Two reinforcing loops (Development and Investment Promotion) and three balancing loops (Pollution, Resource Consumption, and Pollution Control) were constituted. Based on this work, we constructed Stock and Flow Diagrams that embedded a pollutant load model and a lake water quality model into a socioeconomic system dynamics model. The Dianchi Lake in Yunnan Province, China, which is the sixth largest and among the most severely polluted freshwater lakes in China, was employed as a case study to demonstrate the applicability of the model. Water quality parameters considered in the model included chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP). The business-as-usual (BAU) scenario and three alternative management scenarios on spatial adjustment of industries and population (S1), wastewater treatment capacity construction (S2), and structural adjustment of agriculture (S3), were simulated to assess the effectiveness of certain policies in improving water quality. Results showed that S2 is most effective scenario, and the COD, TN, and TP concentrations in Caohai in 2030 are 52.5, 10.9, and 0.8 mg/L, while those in Waihai are 9.6, 1.2, and 0.08 mg/L, with sustained development in the watershed. Thus, the model can help support the decision making required in development and environmental protection strategies.

  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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Wind-induced flow velocity effects on nutrient concentrations at Eastern Bay of Lake Taihu, China.

    PubMed

    Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Jianwei; Gao, Xiaomeng; Wang, Wencai; Acharya, Kumud

    2017-07-01

    Shallow lakes are highly sensitive to respond internal nutrient loading due to wind-induced flow velocity effects. Wind-induced flow velocity effects on nutrient suspension were investigated at a long narrow bay of large shallow Lake Taihu, the third largest freshwater lake in China. Wind-induced reverse/compensation flow and consistent flow field probabilities at vertical column of the water were measured. The probabilities between the wind field and the flow velocities provided a strong correlation at the surface (80.6%) and the bottom (65.1%) layers of water profile. Vertical flow velocity profile analysis provided the evidence of delay response time to wind field at the bottom layer of lake water. Strong wind field generated by the west (W) and west-north-west (WNW) winds produced displaced water movements in opposite directions to the prevailing flow field. An exponential correlation was observed between the current velocities of the surface and the bottom layers while considering wind speed as a control factor. A linear model was developed to correlate the wind field-induced flow velocity impacts on nutrient concentration at the surface and bottom layers. Results showed that dominant wind directions (ENE, E, and ESE) had a maximum nutrient resuspension contribution (nutrient resuspension potential) of 34.7 and 43.6% at the surface and the bottom profile layers, respectively. Total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) average concentrations were 6.38, 1.5, and 0.03 mg/L during our field experiment at Eastern Bay of Lake Taihu. Overall, wind-induced low-to-moderate hydrodynamic disturbances contributed more in nutrient resuspension at Eastern Bay of Lake Taihu. The present study can be used to understand the linkage between wind-induced flow velocities and nutrient concentrations for shallow lakes (with uniform morphology and deep margins) water quality management and to develop further models.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. Temporal and spatial trends in water quality of Lake Taihu, China: analysis from a north to mid-lake transect, 1991-2011.

    PubMed

    Akyuz, Dilek Eren; Luo, Liancong; Hamilton, David P

    2014-06-01

    Interpretations of state and trends in lake water quality are generally based on measurements from one or more stations that are considered representative of the response of the lake ecosystem. The objective of this study is to examine how these interpretations may be influenced by station location in a large lake. We addressed this by analyzing trends in water quality variables collected monthly from eight monitoring stations along a transect from the central lake to the north in Lake Taihu (area about 2,338 km(2)), China, from October 1991 to December 2011. The parameters examined included chlorophyll a (Chl a), total nitrogen (TN), and total phosphorus (TP) concentrations, and Secchi disk depth (SD). The individual variables were increasingly poorly correlated among stations along the transect from the central lake to the north, particularly for Chl a and TP. The timing of peaks in individual variables was also dependent on station location, with spectral analysis revealing a peak at annual frequency for the central lake station but absence of, or much reduced signal, at this frequency for the near-shore northern station. Percentage annual change values for each of the four variables also varied with station and indicated general improvement in water quality at northern stations, particularly for TN, but little change or decline at central lake stations. Sediment resuspension and tributary nutrient loads were considered to be responsible for some of the variability among stations. Our results indicate that temporal trends in water quality may be station specific in large lakes and that calculated whole-lake trophic status trends or responses to management actions may be specific to the station(s) selected for monitoring and analysis. These results have important implications for efficient design of monitoring programs that are intended to integrate the natural spatial variability of large lakes.

  3. 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.

  4. 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.

  5. 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…

  6. 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

  7. [Variation of water quality and trophic state of Lake Tianmu, China].

    PubMed

    Gao, Yong-Xia; Zhu, Guang-Wei; He, Ran-Ran; Wang, Fang

    2009-03-15

    Water quality survey was carried out in 2006 and 2007 in Lake Tianmu (Shahe Reservoir) of China in order to make clear the eutrophication reasons of urban lake-type reservoirs in the middle and lower reaches of Yangtze River, and then put forward the corresponding control measures for such reservoirs. The survey frequency was once a month in 2006 and once two months from May 2007 to Dec. 2007. The results indicate that total nitrogen (TN) and total phosphorus (TP) average concentrations were 1.49 mg/L and 0.06 mg/L respectively in 2006, which are 2.7 and 2 times those of 2001-2002. The average permanganate index was 3.68 mg/L in 2006 and it is a little higher than that of 2001-2002. Secchi disk depth (SD) was 1.2 m in 2006 and it is 25 cm lower than that of 2001-2002. The average algal biomass of 2006 was 46.39 mg/L. All of these show that Lake Tianmu has been situated meso-eutrophication in 2006 from the meso to meso-eutrophication in 2001-2002. Control measures of Lake Tianmu were put forward according to the joint survey results of water quality, sediments, fishery, plankton, benthos etc. in 2006, which considered exogenous, endogenesis and substance cycle of the lake ecosystem in together. The measures pointed out that it was needed to control the pollution of agriculture, river, tourism, soil and water erosion as well as fishery etc. in order to increase SD of the reservoirs. TN and TP average concentrations in 2007 were 1.25 mg/L and 0.05 mg/L respectively, and the average algal biomass of 2007 was 22.56 mg/L. Water quality variation between 2006 and 2007 showed that the control measures had effect on reducing nutrients contents and phytoplankton biomass of the lake.

  8. 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

  9. Scenario analysis of the impacts of socioeconomic development on phosphorous export and loading from the Dongting Lake watershed, China.

    PubMed

    Hou, Ying; Chen, Weiping; Liao, Yuehua; Luo, Yueping

    2017-09-27

    Socioeconomic development in lake watersheds is closely related with lake nutrient pollution. As the second largest freshwater lake in China, the Dongting Lake has been experiencing an increase in nutrient loading and a growing risk of eutrophication. This study aimed to reveal the likely impacts of the socioeconomic development of the Dongting Lake watershed on the phosphorous pollution in the lake. We estimated the contributions from different sources and sub-watersheds to the total phosphorous (TP) export and loading from the Dongting Lake watershed under two most likely socioeconomic development scenarios. Moreover, we predicted the likely permissible and actual TP loadings to the Dongting Lake. Under both two scenarios, three secondary sub-watersheds-the upper and lower reaches of the Xiang River watershed and the Dongting Lake Area-are expected to dominate the contribution to the TP export from the Dongting Lake watershed in 2020. Three primary sub-watersheds-the Dongting Lake Area, the Xiang River, and the Yuan River watersheds-are predicted to be the major contributors to the TP loading from the entire watershed. The two scenarios are expected to have a slight difference in TP export and lake TP loading. Livestock husbandry is expected to be the predominant anthropogenic TP source in each of the sub-watersheds under both scenarios. Compared to 2010, permissible TP loading is not expected to increase but actual TP loading is predicted to grow significantly in 2020. Our study provides methodologies to identify the key sources and regions of lake nutrient loading from watersheds with complex socioeconomic context, and to reveal the potential influences of socioeconomic development on nutrient pollution in lake watersheds.

  10. Spatial-Temporal Variation of the Radiometric Color of the Largest Ten Lakes in China

    NASA Astrophysics Data System (ADS)

    Li, J.

    2016-02-01

    The optical properties of inland waters are complicated, limiting the use of remote sensing to monitor inland water quality in large regions over long time periods. The radiometric color of water, reflecting overall water quality, is an important parameter in traditional water quality investigations. In this study, we retrieved the Forel-Ule (FU) class radiometric color parameters from MODIS surface reflectance product (MOD09) image, and analyzed its long term time-series variation in the largest ten lakes in China during 2000-2012. Based on validation by in situ measured reflectance data, the MOD09-derived FU products are reliable, with a linear correlation coefficient of 0.97, RMSE of 1.2, and average relative error of 7.7%. Since FU class is an optical parameter, it can be derived from optical remote sensing data without seasonal and area limitations. The FU class products were used to analyze the spatial and temporal variations of turbidity and trophic states in the ten lakes. The largest ten lakes in China include typical types with different optical properties, so the FU class can also be used to assess the quality of other inland waters. The FU class retrieval method can also be applied to other remote sensing data after a simple normalization process. As a result, the FU class radiometric color can be used to assess inland water quality in large regions over long time periods.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Monitoring the organotin contamination in the Taihu Lake of China by bivalve mussel Anodonta woodiana.

    PubMed

    Yang, Jian; Harino, Hiroya; Liu, Hongbo; Miyazaki, Nobuyuki

    2008-08-01

    As a part of the pilot study on "Freshwater Mussel Watch", butyltin (monobutyltin, MBT; dibutyltin, DB; tributyltin, TBT), and phenyltins (monophenyltin, MPT; diphenyltin DPT; triphenyltin TPT) were analyzed in soft tissues of 15 bivalve mussels Anodonta woodiana sampled from five separate sites (Huzhou, Xueyan, Dapu, Sansandao, and Wulihu) around the Taihu Lake of China in 2004. The residue of total butyltins and total phenyltins in the all mussels ranged 142-1693 and 3.0-90 ng Sn g(-1) dry weight, respectively. Except for the mussels from Xueyan, DBT and MBT accounted more than 60% of total butyltins in those from other four sites. In contrast, TPT were usually almost 100% of the mussels studied. The present study provides most recent information about the organotin contamination in the Taihu Lake, and suggests Anodonta woodiana can be used as a suitable bioindicator.

  1. Arsenic pollution and its treatment in Yangzonghai lake in China: In situ remediation.

    PubMed

    Chen, Jing; Wang, Shixiong; Zhang, Shu; Yang, Xiangjun; Huang, Zhangjie; Wang, Chong; Wei, Qunyan; Zhang, Genlin; Xiao, Jun; Jiang, Fengzhi; Chang, Jun; Xiang, Xing; Wang, Juan

    2015-12-01

    In this study, the effect of direct atomization and spraying a ferric chloride (FeCl3) solution to decrease the arsenic concentration and its pollution in Yangzonghai Lake, China, was investigated. Ten ships were used for spraying 6-8t of FeCl3 in the lake every day since October 2009. After spraying, the average concentration of arsenic in Yangzonghai Lake, which has an area of 31 km(2), an average depth of 20 m, and a water storage capacity of 604 million m(3), started to decrease from 0.117 mg L(-1). On 20 September 2010, the lowest arsenic level of 0.021 mg L(-1) was attained, with an arsenic removal rate as high as 82.0%. However, the source of pollution was not eliminated, and local rainfall mainly occurred in September; hence, arsenic concentration from October to December increased to 0.078 mg L(-1). At the beginning of 2011, the As concentration decreased and remained at 0.025-0.028 mg L(-1) from May to September. During the 2 years of FeCl3 treatment, the water quality improved from V Class to II-III Class of the Chinese standards, which remained consistent for 12 months. The total cost for this in situ water treatment was 29 million RMB, which was less than a hundredth of the expected expenditure of 4-7 billion RMB. The treatment method achieved goals such as high arsenic removal rate, easy operation, low cost, and ecological security. In this study, the changing patterns of the concentration of arsenic in Yangzonghai Lake from June 2008 to December 2014 were analyzed, and the following problems were discussed: the stability of iron-arsenic precipitates in the lake, the concentrations of ferric and chloride ions in the lake, the pH of the lake during treatment, the stability of iron-arsenic precipitates in the lakebed sediments, and the variation of phytoplankton species in the lake. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. 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

  3. 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

    2017-04-01

    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.

  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. 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.

  6. Silicon isotope composition of diatoms as a paleoenvironmental proxy in Lake Huguangyan, South China

    NASA Astrophysics Data System (ADS)

    Chen, Jingan; Li, Jian; Tian, Shihong; Kalugin, Ivan; Darin, Andrey; Xu, Sheng

    2012-02-01

    Silicon is essential for the growth of diatoms, which utilize dissolved silicic acid in lake water and form opaline silica (SiO 2· nH 2O). During the uptake of dissolved silicic acid, there is a preferential incorporation of light silicon isotope ( 28Si) into biogenic silica, resulting in the enrichment of heavy silicon isotope ( 30Si) in dissolved silicic acid. The silicon isotope composition of diatom silica (δ 30Si diatom) may thus record changes in the percentage utilization of dissolved silicic acid by diatoms, which can be then related to other aspects of climate/environment. With the aim of exploring the potential of δ 30Si diatom as an indicator of lacustrine environment, here we made the first measurements of δ 30Si diatom in the sediment core from Lake Huguangyan, a closed crater lake in China. The result shows that δ 30Si diatom varies from -0.6‰ to 1.1‰ and displays broad similarities to variations in contents of biogenic silica and organic carbon throughout the sediment core. δ 30Si diatom is a reliable paleotemperature proxy in Lake Huguangyan, which is supported by good correlation between δ 30Si diatom and available temperature records. Heavier δ 30Si diatom indicates greater dissolved silicic acid utilization at higher temperature while lighter δ 30Si diatom reflects decreased utilization at lower temperature. The most negative δ 30Si diatom values in the sediment core occur between AD 1580 and 1920, which suggests AD 1580-1920 was the coldest period in Lake Huguangyan over the past 2000 years, thus providing evidence for the existence of the LIA in tropical South China. There are few means by which to reconstruct the history of temperature changes in tropical terrestrial region. δ 30Si diatom, in this study, has proven to be a new promising paleotemperature proxy in lacustrine sediments, and may play important role in reconstructing past temperature changes at low latitude in the future. Detailed investigations on the silicon

  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. 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.

  9. 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.

  10. The Impact of Land Use Changes on Runoff of Taihu Lake Basin of China

    NASA Astrophysics Data System (ADS)

    Li, Hengpeng; Yang, Guishan; Diao, Yaqin; Li, Pengcheng

    2017-04-01

    Land use/cover changes play a role of "interface" linking human activities and environmental systems. Land use changes alter the hydrological characteristics of the land surface, and have significant impacts on hydrological cycle and water balance, leading to increasing flood disaster. Taihu lake basin is fastest on urbanization among the regions in the east part of China. Impacted by cities' fast expansion, the problem of storm flood disaster is very serious. In this study, land use information was extracted from 5-year's TM/ETM images of 1985, 1995, 2000, 2005 and 2010. A grid-based distributed hydrological model was applied to estimate Runoff response to land use changes by simulating the monthly and annual runoff using long-term rainfall records from 1980 to 2010. Results showed that rapid changes in land use was noted in Taihu Lake catchment, which is characterized by conversion of agricultural land to construction land. The share of construction land increased from 9.7% to 13.4% in 15 years (1985-2000) with the increased area of 1388 km2; In the following 2000-2010, the share of construction land increased from 13.4% to 24.2% with the increased area of 4038 km2. The land use changes during 1985-2000 resulted in an average increase of runoff by 4.37% in the whole Taihu Lake basin, approximately 6.46×108m3. The land use changes during 1985-2010 led to an average increase of runoff by 12.82% in the whole basin, around 18.99×108m3. Based on the analysis of rainfall variation in recent years in Taihu Lake basin, it is concluded that the increasing urban storm floods in Taihu Lake basin are closely related to the fast urbanization process.

  11. 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.

  12. 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.

  13. The 5000-year environmental change and associated human activities at Sokho-nor Lake, Inner Mongolia, P.R. China

    NASA Astrophysics Data System (ADS)

    Lu, Xiangyang; Yuan, Baoyin; Guo, Zhiyu; Li, Kun

    1997-03-01

    Sokho-nor Lake is situated in the western part of Inner Mongolia, Northwest China. Human beings have been living in this area since the New Lithic Age. Throughout history, this area has undergone repeated desert-oasis periods, associated with changing river inputs through time. The varying population in the area has been strongly influenced by the water resources available. Inhabitants included members of the Han race and people from northern nomadic tribes. Their activities in the past were affected by changing lake levels. Today, the lake is completely dry, and the environmental impact on the region is a serious problem.

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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

    2017-04-01

    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.

  1. 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.

  2. 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.

  3. 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.

  4. Screening level of PAHs in sediment core from Lake Hongfeng, Southwest China.

    PubMed

    Guo, Jian-Yang; Wu, Feng-Chang; Zhang, Liang; Liao, Hai-Qing; Zhang, Run-Yu; Li, Wei; Zhao, Xiao-Li; Chen, She-Jun; Mai, Bi-Xian

    2011-05-01

    Using data from a 25-year retrospective of polycyclic aromatic hydrocarbons (PAHs) in sediment core from Lake Hongfeng, Southwest China, their possible sources and potential toxicologic significance were investigated. The total PAH concentrations (16 priority PAHs as proposed by the United States Environmental Protection Agency) in sediments ranged from 2936.1 to 5282.3 ng/g and gradually increased from the analyzed deeper sediments to surface sediments. PAHs were dominated by low molecular-weight components, especially phenanthrene (PHEN) and fluorene (FLU). However, a significantly increased number of high molecular-weight (HMW) PAHs was found in upper segments. The temporal trends of individual PAH species suggest that there may have been a change in energy use from low- to high-temperature combustion, especially after approximately 2001. PAH input to Lake Hongfeng originated mainly from domestic coal combustion and biomass burning, whereas fuel combustion characteristics have also been found in recent years. Sediment-quality assessment implied that potential adverse biologic impact could be a probability for most low-ring PAHs (including naphthalene, acenaphthylene, acenaphthylene, FLU, PHEN, and anthracene). Nevertheless, more concern should be paid to HMW PAHs in the future due to their rapidly increasing trends in upper sediments. Because only one core was analyzed in this study, more work is needed to confirm the sources and toxicity of PAHs in Lake Hongfeng.

  5. 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.

  6. Evaluation of Hyperspectral Indices for Chlorophyll-a Concentration Estimation in Tangxun Lake (Wuhan, China)

    PubMed Central

    Huang, Yaohuan; Jiang, Dong; Zhuang, Dafang; Fu, Jingying

    2010-01-01

    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 (R2 > 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. PMID:20644681

  7. 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.

  8. Distributions, Sources, and Backward Trajectories of Atmospheric Polycyclic Aromatic Hydrocarbons at Lake Small Baiyangdian, Northern China

    PubMed Central

    Qin, Ning; Kong, Xiang-Zhen; Zhu, Ying; He, Wei; He, Qi-Shuang; Yang, Bin; Ou-Yang, Hui-Ling; Liu, Wen-Xiu; Wang, Qing-Mei; Xu, Fu-Liu

    2012-01-01

    Air samples were collected seasonally at Lake Small Baiyangdian, a shallow lake in northern China, between October 2007 and September 2008. Gas phase, particulate phase and dust fall concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured using a gas chromatograph-mass spectrometer (GC-MS). The distribution and partitioning of atmospheric PAHs were studied, and the major sources were identified; the backward trajectories of air masses starting from the center of Lake Small Baiyangdian were calculated for the entire year. The following results were obtained: (1) The total concentration of 16 priority controlled PAHs (PAH16) in the gas phase was 417.2 ± 299.8 ng·m−3, in the particulate phase was 150.9 ± 99.2 ng·m−3, and in dust fall was 6930.2 ± 3206.5 ng·g−1. (2) Vehicle emission, coal combustion, and biomass combustion were the major sources in the Small Baiyangdian atmosphere and accounted for 28.9%, 45.1% and 26.0% of the total PAHs, respectively. (3) Winter was dominated by relatively greater PAHs polluted northwesterly air mass pathways. Summer showed a dominant relatively clean southern pathway, whereas the trajectories in autumn and spring might be associated with high pollution from Shanxi or Henan province. PMID:23118612

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Spatio-Temporal Distribution Patterns in Environmental Factors, Chlorophyll-a and Microcystins in a Large Shallow Lake, Lake Taihu, China

    PubMed Central

    Ye, Rui; Shan, Kun; Gao, Hailong; Zhang, Ruibin; Xiong, Wen; Wang, Yulei; Qian, Xin

    2014-01-01

    The spatio-temporal distribution of environmental factors, chlorophyll-a (Chl-a), and microcystins (MCs) in a shallow lake, Lake Taihu (China), were investigated from 2009 to 2011 on a monthly basis at nine sampling stations. The annual mean concentration ranges of total nitrogen (TN), total phosphorus (TP), Chl-a, MC-LR and MC-RR were 0.17–10.53 mg/L, 0.027–0.581 mg/L, 0.10–129.75 µg/L, 0.013–2.019 µg/L and 0.002–0.794 µg/L, respectively. The average TN, ammonium (NH4+) and TP concentrations in Meiliang Bay decreased from 3.54 to 2.26 mg/L, 0.63 to 0.31 mg/L and 0.150 to 0.124 mg/L, respectively, when compared with values from 2006–2008, indicating that water quality has improved in severe cyanobacterial bloom areas in recent years. Additionally, the distribution of MCs was northern lake areas > western lake areas > central lake areas > macrophyte-dominated areas. Correlation analysis revealed that nutrients were the most important variable accounting for the variation of extracellular MC-LR concentration in heavy cyanobacterial bloom areas of Lake Taihu. During the study period, the maximum MCs concentration reached 2.75 ± 0.27 μg/L in the bloom period in the northern lake areas, which is more than two times the safety limit of 1 μg/L MCs required for drinking water. However, microcystins decreased gradually as the water quality improved from 2009 to 2011, indicating that the risk of MCs exposure was slightly decreased in Lake Taihu. PMID:24830449

  16. Spatio-temporal distribution patterns in environmental factors, chlorophyll-a and microcystins in a large shallow lake, Lake Taihu, China.

    PubMed

    Ye, Rui; Shan, Kun; Gao, Hailong; Zhang, Ruibin; Xiong, Wen; Wang, Yulei; Qian, Xin

    2014-05-14

    The spatio-temporal distribution of environmental factors, chlorophyll-a (Chl-a), and microcystins (MCs) in a shallow lake, Lake Taihu (China), were investigated from 2009 to 2011 on a monthly basis at nine sampling stations. The annual mean concentration ranges of total nitrogen (TN), total phosphorus (TP), Chl-a, MC-LR and MC-RR were 0.17-10.53 mg/L, 0.027-0.581 mg/L, 0.10-129.75 µg/L, 0.013-2.019 µg/L and 0.002-0.794 µg/L, respectively. The average TN, ammonium (NH4(+)) and TP concentrations in Meiliang Bay decreased from 3.54 to 2.26 mg/L, 0.63 to 0.31 mg/L and 0.150 to 0.124 mg/L, respectively, when compared with values from 2006-2008, indicating that water quality has improved in severe cyanobacterial bloom areas in recent years. Additionally, the distribution of MCs was northern lake areas > western lake areas > central lake areas > macrophyte-dominated areas. Correlation analysis revealed that nutrients were the most important variable accounting for the variation of extracellular MC-LR concentration in heavy cyanobacterial bloom areas of Lake Taihu. During the study period, the maximum MCs concentration reached 2.75 ± 0.27 μg/L in the bloom period in the northern lake areas, which is more than two times the safety limit of 1 μg/L MCs required for drinking water. However, microcystins decreased gradually as the water quality improved from 2009 to 2011, indicating that the risk of MCs exposure was slightly decreased in Lake Taihu.

  17. 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.

  18. 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.

  19. 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.

  20. Three-dimensional hydrodynamic and water quality model for TMDL development of Lake Fuxian, China.

    PubMed

    Zhao, Lei; Zhang, Xiaoling; Liu, Yong; He, Bin; Zhu, Xiang; Zou, Rui; Zhu, Yuanguan

    2012-01-01

    Lake Fuxian is the largest deep freshwater lake in China. Although its average water quality meets Class I of the China National Water Quality Standard (CNWQS), i.e., GB3838-2002, monitoring data indicate that the water quality approaches the Class II threshold in some areas. Thus it is urgent to reduce the watershed load through the total maximum daily load (TMDL) program. A three-dimensional hydrodynamic and water quality model was developed for Lake Fuxian, simulating flow circulation and pollutant fate and transport. The model development process consists of several steps, including grid generation, initial and boundary condition configurations, and model calibration processes. The model accurately reproduced the observed water surface elevation, spatiotemporal variations in temperature, and total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) concentrations, suggesting a reasonable numerical representation of the prototype system for further TMDL analyses. The TMDL was calculated using two interpretations of the water quality standards for Class I of the CNWQS based on the maximum instantaneous surface and annual average surface water concentrations. Analysis of the first scenario indicated that the TN, TP and COD loads should be reduced by 66%, 68% and 57%, respectively. Water quality was the highest priority; however, local economic development and cost feasibility for load reduction can pose significant issues. In the second interpretation, the model results showed that, under the existing conditions, the average water quality meets the Class I standard and therefore load reduction is unnecessary. Future studies are needed to conduct risk and cost assessments for realistic decision-making.

  1. Evolution of Chaka Salt Lake in NW China in response to climatic change during the Latest Pleistocene Holocene

    NASA Astrophysics Data System (ADS)

    Xingqi, Liu; Dong, Hailiang; Rech, Jason A.; Matsumoto, Ryo; Bo, Yang; Yongbo, Wang

    2008-04-01

    The Late Pleistocene and Holocene hydrologic balance of Chaka Salt Lake in the eastern Qaidam Basin of NW China was studied based on the analysis of lithostratigraphy, mineralogy, total organic carbon, and total nitrogen from a 9.0-m long sediment core. An age-depth model for the lake sediments is based on eight accelerator mass spectrometry (AMS) 14C measurements of organic matter and a 1700-year radiocarbon reservoir correction. The Pitzer model was used to calculate the sequence of minerals precipitated as a function of salinity assuming that the initial lake water was recharged from adjacent rivers and springs. Lake salinity values were derived from a good match between the calculated and observed mineral sequences. Our multi-proxy based hydrologic reconstruction of Chaka Lake indicates that it was a clastic-dominated, freshwater lake between 17.2 and 11.4 cal ka BP, which may have resulted from the input of glacial water into the lake at that time. During the Lateglacial and Holocene, a warm climatic regime predominated between 13.9 and 12.7 cal ka BP and then a cold climatic regime prevailed between 12.7 and 11.4 cal ka BP. These warm and cold periods correlate with the Bølling-Allerød and Younger Dryas events in the region. Beginning at 11.4 cal ka BP, a saline or hypersaline lake developed, which may have resulted from increased summer insolation and temperatures. These conditions persisted throughout the Holocene. Modeling indicates that lake salinity fluctuated between 66 and 223 ppt from 11.4 to 7.2 cal ka BP and then increased to 223-322 ppt between 7.2 and 6.0 cal ka BP, when most regions of China recorded high moisture availability (i.e. the so-called "mid-Holocene Climatic Optimum"). Lake salinity decreased to 66-223 ppt during a short time period between 6.0 and 5.3 cal ka BP, possibly caused by reduced evaporation. Subsequently, salinity values rapidly increased to 223-322 ppt between 5.3 and 5.2 cal ka BP and a hypersaline lake with a salinity

  2. [Composition and Environmental Effects of LFOM and HFOM in "Incense-Ash" Sediments of West Lake, Hangzhou, China].

    PubMed

    Li, Jing; Zhu, Guang-wei; Zhu, Meng-yuan; Gong, Zhi-jun; Xu, Hai; Yang, Gui-jun

    2015-06-01

    To understand the organic matter pollution characteristic and its relationship with nitrogen, phosphorus and other nutrients in sediments of high organic matter type of urban shallow lakes, the organic matter content, light fraction organic matter (LFOM), heavy fraction organic matter (HFOM), and nitrogen and phosphorus contents were investigated in eight different regions of West Lake, Hangzhou. The results showed that, the organic matter content of the west lake sediment was 28-251 g x kg(-1), belonging to typical high organic matter sediment. The difference of organic matter content in different lake sediments was very big. The sediments located at the input site of water diversion engineering had significantly lower organic content than the rest regions. The LFOM content of West Lake sediment ranged 0.57-9.17 g x kg(-1), which averagely occupied 2.83% of the total organic matter, and the HFOM content ranged 5.35-347.41 g x kg(-1), which occupied more than 90% of the total organic matter. Compared to other shallow lakes located in China, sediments of West Lake had significantly high percentage of HFOM/LFOM ratio. But the HFOM content was obviously on the high side, reflecting the west lake as an urban lake with a long history, as well as high organic matter pollution load and sediment humification degree. Both the content and the ratio of LFOM/HFOM in sediment were related to nitrogen and phosphorus contents in sediment. This suggested that the composition of organic matter in West Lake sediments had potential control ability for the internal loading of N and P of the lake.

  3. 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. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Characteristics of influenza H13N8 subtype virus firstly isolated from Qinghai Lake Region, China.

    PubMed

    Dong, Jie; Bo, Hong; Zhang, Ye; Dong, Libo; Zou, Shumei; Huang, Weijuan; Liu, Jia; Wang, Dayan; Shu, Yuelong

    2017-09-18

    Since the highly pathogenic H5N1 influenza caused thousands of deaths of wild bird in this area in 2005, Qinghai Lake in China has become a hot spot for study of the influence of avian influenza to migratory wild birds. However, the ecology and evolution of low pathogenic avian influenza virus in this region are limited. This project-based avian influenza surveillance in Qinghai lake region was initiated in year 2012. Samples of wild bird feces and lake surface water were collected in Qinghai Lake in year 2012.Virus isolation was conducted on embryonated chicken eggs. The influenza A virus was determined by rRT-PCR. Virus sequences were acquired by deep sequencing. The phylogenetic correlation and molecular characteristics of the viruses were analyzed. The virus growth and infection features, receptor binding preference were studied, and pathogenicity in vitro as well as. Two H13N8 subtype influenza viruses were isolated. The viruses are phylogenetically belong to Eurasian lineage. Most of the genes are associated with gull origin influenza virus except PB1 gene, which is most probably derived from Anseriformes virus. The evidence of interspecies reassortment was presented. The two viruses have limited growth capacity on MDCK and A549 cells while grow well in embryonated eggs. The dual receptor binding features of the two viruses was shown up. The low pathogenic features were determined by trypsin dependence plaque formation assay. The two H13N8 subtype influenza viruses are highly associated with gull origin. The interspecies reassortment of H13 subtype virus among Anseriforme sand Charadriiformes wild birds emphasizes the importance of strengthening avian influenza surveillance in this region. This study is helpful to understand the ecology, evolution and transmission pattern of H13 subtype influenza virus globally.

  5. 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.

  6. Occurrence and controls on transport and transformation of nitrogen in riparian zones of Dongting Lake, China.

    PubMed

    Zhao, Shan; Zhou, Nianqing; Liu, Xiaoqun

    2016-04-01

    Dongting Lake is the second largest freshwater lake in China. It is suffering from significant eutrophication as a result of excessive nutrients inputs, among which nitrogen (N) is becoming a major contributor. The objective of this study is to document the occurrence and controls on N transport and transformation in riparian zones of Dongting Lake wetland. Field experiments were conducted in the cultivated Li River (LR) and uncultivated Yuan River (YR) regions of the wetlands from June to November, 2014. Groundwater depth, redox potential (Eh), pH, and temperature were measured in situ. Groundwater and surface water samples were collected to determine concentrations of nitrate nitrogen (NO3 (-)-N), nitrite nitrogen (NO2 (-)-N), and ammonia nitrogen (NH4 (+)-N). The results showed that NH4 (+)-N was the dominant N pollutant with maximum average value of 2.7760 mg L(-1). All the groundwater samples were rated to Class V based on NH4 (+)-N content according to the groundwater quality standard, indicating the load of N in riparian zones had exceeded their capacity for assimilation and purification. Internal controls (including Eh and pH, temperature, and groundwater depth) and external controls (including surface water, land use, and rainfall) were analyzed in detail. The results suggested that Eh and pH were more significant in controlling N transport and transformation than temperature and groundwater depth; external controls influenced N fates through imposing an effect on internal controls. This study will provide important insights and a scientific basis for N pollution treatment and better protection of the Dongting Lake wetlands.

  7. 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.

  8. 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.

  9. Assessing river water quality using water quality index in Lake Taihu Basin, China.

    PubMed

    Wu, Zhaoshi; Wang, Xiaolong; Chen, Yuwei; Cai, Yongjiu; Deng, Jiancai

    2017-09-05

    Lake Taihu Basin, one of the most developed regions in China, has received considerable attention due to its severe pollution. Our study provides a clear understanding of the water quality in the rivers of Lake Taihu Basin based on basin-scale monitoring and a water quality index (WQI) method. From September 2014 to January 2016, four samplings across four seasons were conducted at 96 sites along main rivers. Fifteen parameters, including water temperature, pH, dissolved oxygen (DO), conductivity, turbidity (tur), permanganate index (CODMn), total nitrogen, total phosphorus, ammonium (NH4-N), nitrite, nitrate (NO3-N), calcium, magnesium, chloride, and sulfate, were measured to calculate the WQI. The average WQI value during our study period was 59.33; consequently, the water quality was considered as generally "moderate". Significant differences in WQI values were detected among the 6 river systems, with better water quality in the Tiaoxi and Nanhe systems. The water quality presented distinct seasonal variation, with the highest WQI values in autumn, followed by spring and summer, and the lowest values in winter. The minimum WQI (WQImin), which was developed based on a stepwise linear regression analysis, consisted of five parameters: NH4-N, CODMn, NO3-N, DO, and tur. The model exhibited excellent performance in representing the water quality in Lake Taihu Basin, especially when weights were fully considered. Our results are beneficial for water quality management and could be used for rapid and low-cost water quality evaluation in Lake Taihu Basin. Additionally, we suggest that weights of environmental parameters should be fully considered in water quality assessments when using the WQImin method. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. 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

  11. 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

  12. Vertical distributions of bound saturated fatty acids and compound-specific stable carbon isotope compositions in sediments of two lakes in China: implication for the influence of eutrophication.

    PubMed

    Wang, Lifang; Xiong, Yongqiang; Wu, Fengchang; Li, Qiuhua; Lin, Tian; Giesy, John P

    2014-11-01

    Lakes Dianchi (DC) and Bosten (BST) were determined to be at different stages of eutrophication, by use of total organic carbon content, bulk carbon isotopic composition, bulk nitrogen isotopic composition, and bound saturated fatty acid (BSFA) concentrations in sediment cores. A rapid increase in the supply of organic matter (OM) to DC began after the 1950s, while the environment and trophic status of BST remained constant as indicated by characteristics of OM input to sediments. The BSFA ratios of nC14 + nC16 + nC18/nC24 + nC26 + nC28 increase upward from 7 to 13 in the DC core, which are significantly greater than those from BST (2 to 3). This result is consistent with algae or bacteria being the dominant contribution of the OM increase induced by eutrophication in DC. The positive shift of nC16 compound-specific δ (13)C in the upper section might be an indicator of excess algal productivity, which was observed in the two lakes. The positive shifts of compound-specific δ (13)C of other BSFAs were also observed in the upper section of the core only from DC. The observed trends of compound-specific δ(13)C of BSFA originated from different sources became more consistent, which reflected the intensified eutrophication had profoundly affected production and preservation of OM in DC. The results observed for BST indicated that accumulation of algae did not affect the entire aquatic ecosystem until now.

  13. 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

  14. 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.

  15. 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

  16. 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

  17. Paleohydrology of China Lake basin and the context of early human occupation in the northwestern Mojave Desert, USA

    NASA Astrophysics Data System (ADS)

    Rosenthal, Jeffrey S.; Meyer, Jack; Palacios-Fest, Manuel R.; Young, D. Craig; Ugan, Andrew; Byrd, Brian F.; Gobalet, Ken; Giacomo, Jason

    2017-07-01

    Considerable prior research has focused on the interconnected pluvial basins of Owens Lake and Searles Lake, resulting in a long record of paleohydrological change in the lower Owens River system. However, the published record is poorly resolved or contradictory for the period encompassing the terminal Pleistocene (22,000 to 11,600 cal BP) and early Holocene (11,600-8200 cal BP). This has resulted in conflicting interpretations about the timing of lacustrine high stands within the intermediate basin of China Lake, which harbors one of the most extensive records of early human occupation in the western Great Basin and California. Here, we report a broad range of radiocarbon-dated paleoenvironmental evidence, including lacustrine deposits and shoreline features, tufa outcrops, and mollusk, ostracode, and fish bone assemblages, as well as spring and other groundwater-related deposits (a.k.a. ;black mats;) from throughout China Lake basin, its outlet, and inflow drainages. Based on 98 radiocarbon dates, we develop independent evidence for five significant lake-level oscillations between 18,000 and 13,000 cal BP, and document the persistence of groundwater-fed wetlands from the beginning of the Younger Dryas through the early Holocene (12,900-8200 cal BP); including the transition from ground-water fed lake to freshwater marsh between about 13,000 and 12,600 cal BP. Results of this study support and refine existing evidence that shows rapid, high-amplitude oscillations in the water balance of the Owens River system during the terminal Pleistocene, and suggest widespread human use of China Lake basin began during the Younger Dryas.

  18. Huguangyan Maar Lake (SE China): A solid record of atmospheric mercury pollution history in a non-remote region

    NASA Astrophysics Data System (ADS)

    Zeng, Yan; Chen, Jingan; Yang, Yongqiong; Wang, Jianxu; Zhu, Zhengjie; Li, Jian

    2017-10-01

    Mercury is a highly toxic metal that can cause harm to environment and human health. As atmospheric deposition is the main source of total Hg input to aquatic system in remote and pristine regions, almost all the studies on atmospheric Hg pollution history concentrated in these areas, while the studies in non-remote areas are much limited, especially for the long history records. In this study, Huguangyan Maar Lake, an undisturbed lake system at low altitude in China, was selected to reconstruct the atmospheric mercury pollution history. Variation patterns of TOC, Hg and non-residual Sr in the sediment core indicated that, compared to the direct atmospheric Hg deposition, the effect of either Hg scavenging from water column by algae or the catchment inputs of previously deposited Hg on the Hg accumulation in the lake sediment was limited. The sediment Hg content in Huguangyan Lake was mainly controlled by the atmospheric Hg deposition, and thus accurately reflected the atmospheric Hg pollution history. The Hga (Hg content from atmospheric deposition) in Huguangyan Lake presented a comparable variation pattern to that in remote sites. It had the same variation trend as the global atmospheric Hg before 1950 CE, which could be attributed to the Industrial Revolution. After that, it was mainly controlled by Hg emissions from Asian countries. The variation of Hga also indicated that atmospheric Hg deposition accelerated significantly since 2000 CE. This study, along with other investigations in remote sites in China, showed that the sediment Hg in Huguangyan Lake responded to the atmospheric Hg pollution more sensitively than in the alpine regions. It should be noted that, the more intensive acceleration of Hg deposition in Huguangyan Lake may imply that the South of China suffered from much more serious atmospheric Hg pollution than previous studies revealed.

  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. 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.

  2. Characteristics and causal factors of hysteresis in the hydrodynamics of a large floodplain system: Poyang Lake (China)

    NASA Astrophysics Data System (ADS)

    Zhang, X. L.; Zhang, Q.; Werner, A. D.; Tan, Z. Q.

    2017-10-01

    A previous modeling study of the lake-floodplain system of Poyang Lake (China) revealed complex hysteretic relationships between stage, storage volume and surface area. However, only hypothetical causal factors were presented, and the reasons for the occurrence of both clockwise and counterclockwise hysteretic functions were unclear. The current study aims to address this by exploring further Poyang Lake's hysteretic behavior, including consideration of stage-flow relationships. Remotely sensed imagery is used to validate the water surface areas produced by hydrodynamic modeling. Stage-area relationships obtained using the two methods are in strong agreement. The new results reveal a three-phase hydrological regime in stage-flow relationships, which assists in developing improved physical interpretation of hysteretic stage-area relationships for the lake-floodplain system. For stage-area relationships, clockwise hysteresis is the result of classic floodplain hysteretic processes (e.g., restricted drainage of the floodplain during recession), whereas counterclockwise hysteresis derives from the river hysteresis effect (i.e., caused by backwater effects). The river hysteresis effect is enhanced by the time lag between the peaks of catchment inflow and Yangtze discharge (i.e., the so-called Yangtze River blocking effect). The time lag also leads to clockwise hysteresis in the relationship between Yangtze River discharge and lake stage. Thus, factors leading to hysteresis in other rivers, lakes and floodplains act in combination within Poyang Lake to create spatial variability in hydrological hysteresis. These effects dominate at different times, in different parts of the lake, and during different phases of the lake's water level fluctuations, creating the unique hysteretic hydrological behavior of Poyang Lake.

  3. 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.

  4. Spatial heterogeneity of cyanobacterial communities and genetic variation of microcystis populations within large, shallow eutrophic lakes (Lake Taihu and Lake Chaohu, China).

    PubMed

    Cai, Yuanfeng; Kong, Fanxiang; Shi, Limei; Yu, Yang

    2012-01-01

    Cyanobacteria, specifically Microcystis, usually form massive blooms in eutrophic freshwater lakes. Cyanobacterial samples were collected from eight sites of both Lake Taihu and Lake Chaohu in late summer to determine the diversity and distribution pattern of cyanobacteria and Microcystis in large, shallow, entropic lakes with significant spatial heterogeneity and long-term Microcystis bloom. Molecular methods based on denaturing gradient gel electrophoresis and clone library analysis were used. A similar heterogeneous distribution pattern of cyanobacteria in both lakes was observed. Most parts of these two lakes with high trophic level were dominated by Microcystis. However, in the regions with low trophic levels as well as low concentrations of chlorophyll a, Synechococcus occupied a considerable percentage. Different morphospecies and genotypes dominated the bloom-forming Microcystis populations in these two lakes. Microcystis viridis and Microcystis novacekii were dominant in Lake Chaohu, whereas Microcystis flos-aquae was dominant in Lake Taihu. Only 2 of thel3 Microcystis operational taxonomic units were shared between these two lakes. Analysis of molecular variance based on 16S to 23S internal transcribed spacer sequences indicated the significAnt genetic differentiation of Microcystis between these two lakes (F(ST) = 0.19, p < 0.001). However, only 19.46% of the genetic variability was explained by the population variation between lakes, whereas most (80.54%) of the genetic variability occurred within the lakes. Phylogenetic analysis revealed no phylogeographic structure of Microcystis population in these two lakes, as illustrated by their cosmopolitan nature. Our results revealed that spatial heterogeneity within lakes has more impact on the cyanobacterial diversity than geographical isolation in a local scale.

  5. 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.

  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. Carbon dioxide and energy fluxes over a large shallow lake in China

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaosong

    2017-04-01

    The turbulent exchange of carbon dioxide and energy between water and atmosphere over lakes differ from those over vegetated surfaces due to high heat capacity of water and different water ecological environment. For a shallow lake, the underlying surface generally changes between water covered and land covered with water level fluctuation, which significantly influences carbon dioxide and energy fluxes. Continuous measurement of the carbon dioxide (CO2), latent (LE) and sensible (H) heat fluxes was made using the eddy covariance method over the Poyang Lake, the largest fresh lake in China, from August 2013 to December 2015. Results indicated that the surface energy budget has a strong seasonal pattern, with peaks in LE and H observed in early August and September. There was 10 days delay between the net radiation and the latent heat flux. More net radiation (Rn) was allocated to the LE rather than H through the year, with monthly mean LE/Rn of 0.65 and H/Rn of 0.11, which caused Bowen ratio was 0.15 in water-covered period, lower than that in land-covered period. The water heat storage experienced shifting from heat storage to heat release, with maximum heat storage in July and maximum heat release in September. The water heat advection was account for 4% to 10% of Rn and peaked in June. The annual evaporation is 875 mm, 893 mm and 1019 mm in 2013 (from August 2013 to July 2014), 2014 and 2015, which was account for approximately 57% of precipitation in the three years. The large lake acted as a CO2 source in inundating period and a CO2 sink in exposure period. The energy fluxes were controlled by environmental factors with timescale dependence. On daily scale, the LE and H were highly correlated with product of wind speed and vapor pressure deficit (UVPD) or wind speed (U) in the water-covered period, and with Rn in the land-covered period. Monthly LE, H and annual H were controlled by Rn, while annual LE was primarily dependent on water depth. Annual CO2 budget

  8. 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.

  9. Tracking four-decade inundation changes with multi-temporal satellite images in China's largest freshwater lake

    NASA Astrophysics Data System (ADS)

    Wu, Guiping

    2017-04-01

    Poyang Lake is the largest freshwater lake in China. The lake has undergone remarkable spatio-temporal changes in both short- and long-term scales since 1970s, resulting in significant hydrological, ecological and economic consequences. Remote sensing techniques have advantages for large-scale studies, by offering images at different spatial and spectral resolutions. However, due to technical difficulties, no single satellite sensor can meet the needs for high spatio-temporal resolution required for such monitoring. In this study, using Landsat Thematic Mapper (TM) and Moderate Resolution Imaging Spectroradiometer (MODIS) images collected between 1973 and 2012, we documented and investigated the short- and long-term characteristics of lake inundation based on Normalized Difference Water Index (NDWI). First, we presented a novel downscaling method based on the NDWI statistical regression algorithm to generate small-scale resolution inundation map (30m) from coarse MODIS data (500m). The downscaling is a linear calibration of the NDWI index from MODIS imagery to Landsat imagery, which is based on the assumption that the relationships between fine resolution and coarse resolution are invariable. Second, Tupu analysis method was further performed to explore the spatial-temporal distribution and changing processes of lake inundation based on downscaling inundation maps. Then, a defined water variation rate (WVR) and inundation frequency (IF) indicator was used to reveal seasonal water surface submersion/exposure processes of lake expansion and shrinkage in different zones. Finally, mathematical statistics methods were utilized to explore the possible driving mechanisms of the revealed change patterns with meteorological data and hydrological data. The results show that, there is a high correlation (mean absolute error of 3.95% and an R2 of 0.97) between the MODIS- and Landsat-derived water surface areas in Poyang Lake. Over the past 40 years, a declining trend to a

  10. China's war on waste and pollution.

    PubMed

    Lei, X

    1993-01-01

    The water level of one of the longest rivers in the world, the Yangtze in China, fell 20 cm below sea level in February 1993 at Shashi in Hubei Province, the lowest water level in 20 years. In 1993, black-headed gulls left for their annual migration 3 months early because the deteriorating water environment in Dianchi Lake in Kunming, Yunnan Province, could not support them. China's total surface run-off is among the world's top 5. Yet it suffers a water deficit due to its large population size (88th in per capita water volume, 25% of the world average). No more than 650 million people would be the ideal population size for China's limited water resources. The urban water supply capacity increases 7% each year, but demand increases 10%. In 1992, 63% of the cities had water shortages. An expanding rural population has reclaimed land from lakes to produce food crops. China has an uneven distribution of water resources and rainfall. Many Chinese cities have drawn too much groundwater, causing land subsidence and declining groundwater levels. For example, the groundwater table in Xi' an has fallen more than 80 m in the last 40 years. The water situation is the leading obstacle to economic development in China. Large-scale water diversion projects are very expensive. It is imperative that China expand water resources by reducing waste and pollution. The Chinese parliament has passed 11 laws and decrees on water which resolve water disputes between provinces. Seepage and other flaws result in the loss of more than 50% of the water used in irrigated fields. China has introduced water-saving irrigation techniques (sprinkling and drip irrigation). Industry plans to recycle 15% of the water it uses, saving 5.25 billion cu.m annually. 63% of industrial waste water is treated before discharge, but individual factories dispose of the waste, polluting the water supply. Most of the treatment is not 2-stage treatment, though. Water conservation is of key importance for China.

  11. 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.

  12. Extraction and analysis of spectral characteristics of lakes in northeast China based on MERSI

    NASA Astrophysics Data System (ADS)

    Feng, R.; Chen, P. S.; Wu, J. W.; Yu, W. Y.; Ji, R. P.; Zhang, Y. S.

    2017-06-01

    Base on Northeast China region, according to land surface reflectivity of FY3B/MERSI data from 2011-2015, the underlying surface index of lakes and reservoirs, the original spectrum, normalized difference water index during different periods, were obtained. The monthly change was analyzed as well. Meanwhile, combined with GIS data, the model of extracting area was built. Using the TM data, the method was verified. The results indicated that the spectral reflectance are in accordance with the characteristics of water, with high reflection area in blue and green bands, low reflection area in near-infrared band (< 6%), and more obvious reflectance spectral characteristics corresponding to higher cleanliness of water. The method could make area extracting in large scale. The method has higher accuracy up to 90%, which provides a preliminary method for the application of domestic satellite data.

  13. 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.

  14. Sources, distribution and export coefficient of phosphorus in lowland polders of Lake Taihu Basin, China.

    PubMed

    Huang, Jiacong; Gao, Junfeng; Jiang, Yong; Yin, Hongbin; Amiri, Bahman Jabbarian

    2017-09-21

    Identifying phosphorus (P) sources, distribution and export from lowland polders is important for P pollution management, however, is challenging due to the high complexity of hydrological and P transport processes in lowland areas. In this study, the spatial pattern and temporal dynamics of P export coefficient (PEC) from all the 2539 polders in Lake Taihu Basin, China were estimated using a coupled P model for describing P dynamics in a polder system. The estimated amount of P export from polders in Lake Taihu Basin during 2013 was 1916.2 t/yr, with a spatially-averaged PEC of 1.8 kg/ha/yr. PEC had peak values (more than 4.0 kg/ha/yr) in the polders near/within the large cities, and was high during the rice-cropping season. Sensitivity analysis based on the coupled P model revealed that the sensitive factors controlling the PEC varied spatially and changed through time. Precipitation and air temperature were the most sensitive factors controlling PEC. Culvert controlling and fertilization were sensitive factors controlling PEC during some periods. This study demonstrated an estimation of PEC from 2539 polders in Lake Taihu Basin, and an identification of sensitive environmental factors affecting PEC. The investigation of polder P export in a watershed scale is helpful for water managers to learn the distribution of P sources, to identify key P sources, and thus to achieve best management practice in controlling P export from lowland areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. 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. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. HCH and DDT Residues in Bivalves Anodonta woodiana from the Taihu Lake, China.

    PubMed

    Bian, Xuesen; Liu, Hongbo; Gan, Juli; Li, Rong; Yang, Jian

    2009-01-01

    The present article attempts to use freshwater bivalves Anodonta woodiana for monitoring the pollution of hexachlorocyclohexane isomers (alpha-, beta-, gamma-, delta-HCH), dichlorodiphenyltrichloroethanes (o, p', p, p'-DDT) and metabolites (p, p'-DDE, p, p'-DDD) in the Taihu Lake, China. A total of 36 bivalves were sampled from 4 sites of Huzhou city, Dapu of Yixing city, Xueyan of Changzhou city, and Wulihu of Wuxi city around the lake in August-October 2004. The organochlorines were detected in all bivalves, and the mean concentration of SigmaDDTs (7.07 ng/g wet weight) was significantly higher than that of SigmaHCHs (2.37 ng/g wet weight). Overall, SigmaHCHs are at the highest concentrations in the bivalves from the Dapu and Huzhou site, whereas SigmaDDTs are at highest concentrations in the bivalves from the Wulihu site. Compositions of SigmaHCHs were predominated by alpha- and gamma-HCH isomers in the bivalves from all four study sites. Among these sampling sites, p, p'-DDT exhibited the highest percentage in the bivalves from Huzhou site. Furthermore, significant regional variations in compositions of both SigmaDDTs and SigmaHCHs had been identified. The residue levels of SigmaDDTs and SigmaHCHs in the bivalves of the present study were much lower than the corresponding residue limits for aquatic products of Ministry of Agriculture of China, FDA, and FAO/WHO. These findings suggest that Anodonta woodiana could serve as a unique bioindicator to monitor the HCH and DDT pollutions in the freshwater environment.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. Movement analysis of free-grazing domestic ducks in Poyang Lake, China: a disease connection.

    PubMed

    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.

  2. 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.

  3. Characterizing ecological risk for polycyclic aromatic hydrocarbons in water from Lake Taihu, China.

    PubMed

    Guo, Guanghui; Wu, Fengchang; He, Hongping; Zhang, Ruiqing; Feng, Chenglian; Li, Huixian; Chang, Ming

    2012-11-01

    Lake Taihu provides vital ecological services for humans in China; it receives a great deal of attention regarding its ecological and environmental conditions. In this study, the ecological risks of eight individual polycyclic aromatic hydrocarbons (PAHs) in water were assessed using probabilistic distributions of the hazard quotient based on Monte Carlo simulation. The results show that the 95th percentile of the hazard quotients ranged from 0.00074 to 2.831, and the ecological risk of Flua was highest, followed by, in descending order of risk, B[a]P > Pyr > Ant > Phe > Flu > Ace > Chr. The probabilities of hazard quotients exceeding a decision criteria of 0.3 were 18.09%, 6.51%, 3.76%, and 2.85% for Flua, B[a]P, Pyr, and Ant, respectively, indicating their potential ecological risks to aquatic organisms. The spatial distribution of hazard quotients for these four individual PAHs with potential ecological risk were obtained using Geographic Information System (GIS), and similar spatial distribution patterns were also observed in the lake. The highest ecological risks of these four individual PAHs to aquatic organisms were found in Meiliang Bay, followed by Gonghu Bay and Xukou Bay. The uncertainty within the ecological risk assessment was also discussed.

  4. A hundred year record of anthropogenic influences on the sedimentary geochemistry from Lake Sayram, Tianshan Mountains in northwestern China

    NASA Astrophysics Data System (ADS)

    Wu, J.; Shen, B.

    2016-12-01

    Northwestern China has many arid inland lakes and wetlands, and it is characterized with climate variability and human impact. Lake Sayram is a deep, closed lake in the Tianshan Mountains of northwest China. In this study, we explore the trajectory of recent climate and environmental change using a 30-cm sediment record obtained from the center of Lake Sayram. With 210Pb and 137Cs dating and organic-inorganic geochemical methods, including element content, carbonate content, δ13C andδ18O of bulk carbonate, source-specific biomarkers and polycyclic aromatic hydrocarbons (PAHs), we reconstruct regional environmental change over the past about 100 yrs. High evaporation modifies δ13C andδ18O of the dissolved inorganic carbon in lake water and may be responsible for the covariance between δ13C andδ18O of bulk carbonate. Alkenone unsaturation indices are associated with climatic change, and the PAHs and metal contents reflect the impacts of human activities. Constrained cluster analysis of the multi-proxy indices was used to partition sediment deposition into three periods. Prior to 1960, the climate was dryer with high evaporation, and lake water had higher salinity. The vertical distributions of PAHs had little changed and low molecular weight PAHs were dominated PAHs. In this period, there existed one obvious drier climatic event at about 1920s with the sediment record of aeolian dust transport. From the 1960s to 1990s, high molecular weight PAHs and heavy metal delivery to sediments increased slowly, associated with relatively weak economic development in Xinjiang region. Thereafter, contamination by heavy metals increased markedly, especially after the 1990s, a sharp increase in PAHs level and individuals was observed too. The results clearly demonstrate that the environmental change in Lake Sayram before the 1960s strongly depended on the natural discharge, whereas at later stages, it was significantly influenced by human activities.

  5. 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.

  6. 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.

  7. Familial aggregation of human infection with Schistosoma japonicum in the Poyang Lake region, China

    PubMed Central

    Ellis, Magda K.; Li, Yuesheng; Rong, Zhu; Chen, Honggen; McManus, Donald P.

    2005-01-01

    Despite the success of extensive control measures that have been implemented in China for over 50 years, the number of individuals infected with Schistosoma japonicum remains high in the remaining endemic areas. A variance components analysis was undertaken to estimate the heritable and environmental components that contribute to S. japonicum infection in the Poyang Lake region of Jiangxi Province, PR China. The total target population was 3148 from four separate administrative villages. Two thousand seven hundred and five of these comprised 400 families ranging in size from 3 to 188. After adjustments were made for gender, water contact and past history of having had schistosomiasis, the heritable component was estimated to account for as much as 58% of the phenotype variation under the polygenic model. Household was not shown to be an important environmental factor. Incorporating village effects indicated that the results were valid for the total population. We conclude that genetic heritability in this region is high and plays an important role in determining risk of infection with S. japonicum. PMID:16321389

  8. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. 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.

  10. 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

  11. Screening bacterial magnetites of the Holocene sediments in the Huguangyan Maar lake, south China

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Pan, Y.; Zhu, R.; Deng, C.; Han, F.

    2013-12-01

    The Maar lakes are well known as ideal recorders of high-resolution paleo-environmental changes, because of high sedimentary rates and weak physical disturbance. The Huguangyan Maar Lake (21°9' N, 110°17' E) is a meromictic lake located at the tropical region in the Leizhou Peninsula, south China. It has a surface area of 2.3 km^2 and the maximum water depth of ~20 m. In this study surface sediments were collected at different water depth, and a 2 meter gravity core was taken at 13.8 m water depth, which spans the last ~2 kyr. For the 2-m core natural remanent magnetization (NRM), anhysteretic remanent magnetization (ARM) and the isothermal remanent magnetizations (IRM) were performed using 2-G Enterprises pass-through high-resolution cryogenic magnetometers. Hysteresis loops, first-order reversal curves (FORCs), and low-temperature zero field cooling (ZFC) and field cooling (FC) curves were measured on representative samples. The Verwey transition temperature (Tv) was calculated from the FC curve at the maximum dM/dT while the delta ratio was calculated according to Moskowitz et al. (1993). Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations were also conducted on magnetic extracted samples to examine biogenic magnetofossils. The relatively high values of the S-ratios (> 0.9) indicate that low coercivity magnetic particles (likely magnetite) are the dominant mineral in sediments. The selected samples have delta ratios between 1.1 and 1.3. On FORC diagrams samples showed a near close distribution along Bc axis with Bc peaked at ~15 mT and a narrow spread between × 20 mT along Bb axis, indicating of presence of single-domain magnetite with weak magnetic interaction. High-resolution FORC diagrams display a clear central-ridge pattern, indicating presence of magnetite magnetofossils (Egli et al., 2010). In the magnetic extracted samples with high ARM values, detrital titanomagnetite and biogenic elongated prismatic shaped and

  12. 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.

  13. Evaluation of CDOM sources and their links with water quality in the lakes of Northeast China using fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhao, Ying; Song, Kaishan; Wen, Zhidan; Fang, Chong; Shang, Yingxin; Lv, Lili

    2017-07-01

    The spatial distributions of the fluorescence intensities Fmax for chromophoric dissolved organic matter (CDOM) components, the fluorescence indices (FI370 and FI310) and their correlations with water quality of 19 lakes in the Songhua River Basin (SHRB) across semiarid regions of Northeast China were examined with the data collected in September 2012 and 2015. The 19 lakes were divided into two groups according to EC (threshold value = 800 μS cm-1): fresh water (N = 13) and brackish water lakes (N = 6). The fluorescent characteristics of CDOM in the 19 lakes were investigated using excitation-emission matrix fluorescence spectroscopy (EEM) coupled with parallel factor (PARAFAC) and multivariate analysis. Two humic-like components (C1 and C3), one tryptophan-like component (C2), and one tyrosine-like component (C4) were identified by PARAFAC. The component C4 was not included in subsequent analyses due to the strong scatter in some colloidal water samples from brackish water lakes. The correlations between Fmax for the three EEM-PARAFAC extracted CDOM components C1-C3, the fluorescence indices (FI370 and FI310) and the water quality parameters (i.e., TN, TP, Chl-a, pH, EC, turbidity (Turb) and dissolved organic carbon (DOC)) were determined by redundancy analysis (RDA). The results of RDA analysis showed that spatial variation in land cover, pollution sources, and salinity/EC gradients in water quality affected Fmax for the fluorescent components C1-C3 and the fluorescence indices (FI370 and FI310). Further examination indicated that the CDOM fluorescent components and the fluorescence indices (FI370 and FI310) did not significantly differ (t-test, p > 0.05) in fresh water (N = 13) and brackish water lakes (N = 6). There was a difference in the distribution of the average Fmax for the CDOM fluorescent components between C1 to C3 from agricultural sources and urban wastewater sources in hypereutrophic brackish water lakes. The Fmax for humic-like components C1 and

  14. Impacts of urban sprawl on the area of downtown lakes in a highly developing city on central China

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Zhang, Y.

    2016-12-01

    Wuhan city in central China is full of water resources and numerous lakes are located. Downtown lakes have significant ecological value and ornamental value for urban inhabitants in Wuhan. Under the rapid process of urban sprawl, downtown lakes are occupied by impervious areas. This research uses Landsat images to extract land uses from 1991 to 2013 in Wuhan city , and attempts to find out how urban sprawl affects the water body area decline in space. Two largest downtown lakes in Wuhan city, Donghu Lake located in central city and Tangxunhu Lake located in suburbs, are taken as case study area. A direction change index (DCI) is proposed to evaluate the changes of a specific land use in different directions. The results reveal that two downtown lakes are undergoing rapid water body area decline from 1991 to 2013, with decline rate are -0.022 in Donghu watershed and -0.011 in Tangxunhu watershed. 68.26% and 62.50% of the reduced water body is occupied by built-up land in Donghu watershed and Tangxunhu watershed, respectively. According to DCI, the water body reduce is highly correlated with built-up land increase in all direction. Moreover, it is found that in the Donghu watershed the north-west part suffered significant water body area decline, which is close to central city. While in Tangxunhu watershed, the area of water body declined in north-west, south-west and north-east part, and the area obstructed from central city by the lake was suffering less water body area decline. It is concluded that the water body area of downtown lakes are highly affected by the process of urban sprawl, and the lakes in central districts trends to suffer higher descend than that of the downtown lake located in suburbs. Meanwhile, even for the same downtown lake, the area orientating and close to the central city may suffer more rapid decline than the area that does not orientate to the central city.

  15. Occurrence of Arbuscular Mycorrhizas and Dark Septate Endophytes in Hydrophytes from Lakes and Streams in Southwest China

    NASA Astrophysics Data System (ADS)

    Kai, Wang; Zhiwei, Zhao

    2006-02-01

    In this study, the colonization of arbuscular mycorrhizas (AM) and dark septate endophytes (DSE) in 140 specimens of 32 hydrophytes collected from four lakes and four streams in southwest China were investigated. The arbuscular mycorrhizal fungi (AMF) and DSE colonization in these hydrophytes were rare. Typical AM structures were observed in one of the 25 hydrophytic species collected in lakes and six of the 17 species collected in streams.Spores of 10 identified AMF species and an unidentified Acaulospora sp. were isolated from the sediments. The identified AMF came from the four genera, Acaulospora, Gigaspora, Glomus and Scutellospora . Glomus and G. mosseae were the dominant genus and species respectively in these aquatic environments.The presence of DSE in hydrophytes was recorded for the first time. DSE occurred in one of the 25 hydrophyte species collected in lakes and three of the 17 species collected in streams.

  16. Eutrophication in Poyang Lake (Eastern China) over the Last 300 Years in Response to Changes in Climate and Lake Biomass.

    PubMed

    Liao, Mengna; Yu, Ge; Guo, Ya

    2017-01-01

    Poyang Lake is suffering from persistent eutrophication, which is degrading the local ecosystem. A better understanding of the mechanisms that drive eutrophication in lake systems is essential to fight the ongoing deterioration. In this study, hydraulic residence time (HRT) was used to evaluate Poyang Lake's trophic state. A hydrology and ecosystem forced model was constructed to simulate long-term changes in algae and aquatic plant biomass and total phosphorous (TP). A comparison analysis revealed that between 1812 and 1828 (i.e., a consistent-change stage), climate and hydrology were the main driving forces, while algae and aquatic plant biomass contributed only 20.9% to the trophic changes in Poyang Lake. However, between 1844 and 1860 the biomass predominated contributing 63.6%. This could be attributed to nutrient absorption by algae and aquatic plants. A correlation analysis of the water TP and algae and aquatic plant biomass revealed a strong positive relationship. However, the algae and aquatic plant growth rate tended to decline after the biomass reached half of the maximum. This research reconstructs the long-term trophic evolution of Poyang Lake and provides a better understanding of the relationship between climatic and hydrological changes and lake ecosystems.

  17. Comparison of elemental carbon in lake sediments measured by three different methods and 150-year pollution history in Eastern China.

    PubMed

    Han, Y M; Cao, J J; Yan, B Z; Kenna, T C; Jin, Z D; Cheng, Y; Chow, Judith C; An, Z S

    2011-06-15

    Concentrations of elemental carbon (EC) were measured in a 150 yr sediment record collected from Lake Chaohu in Anhui Province, eastern China, using three different thermal analytical methods: IMPROVE_A thermal optical reflectance (TOR), STN_thermal optical transmittance (TOT), and chemothermal oxidation (CTO). Distribution patterns for EC concentrations are different among the three methods, most likely due to the operational definition of EC and different temperature treatments prescribed for each method. However, similar profiles were found for high-temperature EC fractions among different methods. Historical soot(TOR) (high-temperature EC fractions measured by the IMPROVE_A TOR method) from Lake Chaohu exhibited stable low concentrations prior to the late 1970s and a sharp increase thereafter, corresponding well with the rapid industrialization of China in the last three decades. This may suggest that high-temperature thermal protocols are suitable for differentiating between soot and other carbon fractions. A similar soot(TOR) record was also obtained from Lake Taihu (~200 km away), suggesting a regional source of soot. The ratio of char(TOR) (low-temperature EC fraction measured by the IMPROVE_A TOR method, after correction for pyrolysis) to soot(TOR) in Lake Chaohu shows an overall decreasing trend, consistent with gradual changes in fuel use from wood burning to increasing fossil fuel combustions. Average higher char(TOR)/soot(TOR) was observed in Lake Taihu than in Lake Chaohu in the past 150 years, consistent with the longer and more extensive industrialization around the Taihu region.

  18. Complete Genome Sequence of Magnetospirillum sp. ME-1, a Novel Magnetotactic Bacterium Isolated from East Lake, Wuhan, China.

    PubMed

    Ke, Linfeng; Liu, Pengming; Liu, Shan; Gao, Meiying

    2017-08-24

    A novel spiral magnetotactic bacterium, Magnetospirillum sp. ME-1, was isolated from East Lake in China. Here we report the complete genome of ME-1, which contains a 4,551,873-bp circular chromosome and a 5,222-bp circular plasmid. The magnetosome biogenesis-specific genes are located in a 97,664-bp magnetosome genomic island. Copyright © 2017 Ke et al.

  19. Application of Radar Altimetry Methods to Monitoring of Parasitic Disease Transmission: Schistosomiasis in Poyang Lake, China

    NASA Astrophysics Data System (ADS)

    McCandless, M.; Ibaraki, M.; Shum, C.; Lee, H.; Liang, S.

    2008-12-01

    Schistosomiasis is the second-most prevalent tropical disease after malaria affecting two-hundred million people annually world-wide; it shortens lifespan on average by ten years in endemic areas and no vaccine exists. The current control methods of human host chemotherapy and application of molluscicides to the environment do not break the disease transmission cycle. Schistosomiasis transmission in southern China involves an amphibious intermediate host snail for which hydrology is a key factor because the adults need moist vegetation while the juveniles are fully aquatic. Thus, hydrology is a key factor in schistosomiasis transmission and understanding its role can inform control measures. Our objective is to integrate hydrologic, ecologic, and other environmental factors to determine the changes in available snail habitat through space and time. We use radar altimetry measurements to determine water level every 35 days when the Envisat (Environmental Satellite) passes over the lake. The radar altimetry readings have been calibrated to levels from in-situ gauging stations and will support remote analysis of disease transmission potential without the need for gauging station data. A geographic information system was used to combine key factors including water level, topography, and air temperature data to identify areas of available snail habitat. In order to accomplish this, we conducted three steps including: delineating the watershed, specifying potential snail habitat areas through topography and air temperature classification, and calculating the intersection between potential snail habitat and non-flooded areas in the watershed. Statistical analyses of total available habitat area are also conducted. These maps and statistics analyses can be used by public health agencies to monitor snail habitat trends over time. Coupling remote sensing of water levels with a geographic information system model will continue to be important as the hydrology of the lake

  20. Phragmites australis and Typha orientalis in removal of pollutant in Taihu Lake, China.

    PubMed

    Tian, Ziqiang; Zheng, Binghui; Liu, Meizhen; Zhang, Zhenyu

    2009-01-01

    Two plant populations of Phragmites australis and Typha orientalis grown in gravel and sediment substrate were studied to assess their capabilities for purifying polluted water in Taihu Lake, China. The substrate displayed most significant effects on the suspended matter (P < 0.01), with the reduction of 76%-87% and 52%-63% for P. australis, and 83%-86% and 45%-62% for T. orientalis in gravel substrate and sediment substrate, respectively. Both species and substrates significantly decreased the N and P concentrations of water body (P < 0.01). P. australis showed higher total N and P concentrations in tissues than T. orientalis and had a greater potential to remove nutrients from the lake. Phosphate was easily to concentrate in the belowground tissues, while nitrate concentration was higher in leaf and stalk. Therefore, harvesting the aboveground tissues could take most of nitrate out of the sediment. The saturate photosynthetic rate (Asat) of P. australis was higher than that of T. orientalis when grown in sediment substrate. But instance water-use-efficiency (WUEi) (A/E) and intrinsic water use efficiency (A/gs) showed the maximum values of two species grown in river water. With significant difference in gs, however, intercellular CO2 concentration (Ci) had no obvious difference in two species which indicated that high Asat value of P. australis might result from the increased carboxylation capacity of the mesophyll, because of the central role of N in photosynthetic enzymes. Our findings suggest that the plants could absorb most of nitrogen in polluted water, while gravel displayed a high capacity for absorbing the suspended matters and phosphate salts. Therefore, biological and physiological pathways for pollutant removal should be integrated.

  1. 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) (Lake.

  2. 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.

  3. Investigation of the complexity of streamflow fluctuations in a large heterogeneous lake catchment in China

    NASA Astrophysics Data System (ADS)

    Ye, Xuchun; Xu, Chong-Yu; Li, Xianghu; Zhang, Qi

    2017-04-01

    The occurrence of flood and drought frequency is highly correlated with the temporal fluctuations of streamflow series; understanding of these fluctuations is essential for the improved modeling and statistical prediction of extreme changes in river basins. In this study, the complexity of daily streamflow fluctuations was investigated by using multifractal detrended fluctuation analysis (MF-DFA) in a large heterogeneous lake basin, the Poyang Lake basin in China, and the potential impacts of human activities were also explored. Major results indicate that the multifractality of streamflow fluctuations shows significant regional characteristics. In the study catchment, all the daily streamflow series present a strong long-range correlation with Hurst exponents bigger than 0.8. The q-order Hurst exponent h(q) of all the hydrostations can be characterized well by only two parameters: a (0.354 ≤ a ≤ 0.384) and b (0.627 ≤ b ≤ 0.677), with no pronounced differences. Singularity spectrum analysis pointed out that small fluctuations play a dominant role in all daily streamflow series. Our research also revealed that both the correlation properties and the broad probability density function (PDF) of hydrological series can be responsible for the multifractality of streamflow series that depends on watershed areas. In addition, we emphasized the relationship between watershed area and the estimated multifractal parameters, such as the Hurst exponent and fitted parameters a and b from the q-order Hurst exponent h(q). However, the relationship between the width of the singularity spectrum (Δα) and watershed area is not clear. Further investigation revealed that increasing forest coverage and reservoir storage can effectively enhance the persistence of daily streamflow, decrease the hydrological complexity of large fluctuations, and increase the small fluctuations.

  4. 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.

  5. 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.

  6. Eutrophication in Poyang Lake (Eastern China) over the Last 300 Years in Response to Changes in Climate and Lake Biomass

    PubMed Central

    Liao, Mengna; Yu, Ge; Guo, Ya

    2017-01-01

    Poyang Lake is suffering from persistent eutrophication, which is degrading the local ecosystem. A better understanding of the mechanisms that drive eutrophication in lake systems is essential to fight the ongoing deterioration. In this study, hydraulic residence time (HRT) was used to evaluate Poyang Lake’s trophic state. A hydrology and ecosystem forced model was constructed to simulate long-term changes in algae and aquatic plant biomass and total phosphorous (TP). A comparison analysis revealed that between 1812 and 1828 (i.e., a consistent-change stage), climate and hydrology were the main driving forces, while algae and aquatic plant biomass contributed only 20.9% to the trophic changes in Poyang Lake. However, between 1844 and 1860 the biomass predominated contributing 63.6%. This could be attributed to nutrient absorption by algae and aquatic plants. A correlation analysis of the water TP and algae and aquatic plant biomass revealed a strong positive relationship. However, the algae and aquatic plant growth rate tended to decline after the biomass reached half of the maximum. This research reconstructs the long-term trophic evolution of Poyang Lake and provides a better understanding of the relationship between climatic and hydrological changes and lake ecosystems. PMID:28046083

  7. Seven thousand years of records on the mining and utilization of metals from lake sediments in central China.

    PubMed

    Lee, Celine S L; Qi, Shi-Hua; Zhang, Gan; Luo, Chun-Ling; Zhao, Lu Y L; Li, Xiang-Dong

    2008-07-01

    A 268 cm section of sediment core from Liangzhi Lake in Hubei province in central China was used to assess the use and accumulation of metals in the lake in the past 7,000 years. The concentrations of trace metals, including Cu, Pb, Ni, and Zn, and major elements, Ca, Fe, and Mg, in a 14C- dated segment of sediment core were analyzed. Historical trends on the input of metals to Liangzhi Lake from around 5000 BC to the present were recorded in the sediments, representing about 7,000 years of history on the mining and utilization of metals in central China. The concentrations of Cu, Ni, Pb, and Zn increased gradually from about 3000 +/- 328 BC, indicating the start of the Bronze Age in ancient China. During the period 467 +/- 257 to 215 +/- 221 AD, there was a rapid increase in the concentrations of these metals in the sediments, indicating enormous inputs of these metals at that time. This era corresponded to China's Warring States Period (475- 221 BC) and the early Han Dynasty (206 BC-220 AD), during which copper and lead were extensively used in making bronze articles such as vessels, tools, and weapons. From 1880 +/- 35 AD to the early 1900s, there was also a significant increase in the concentrations of metals such as Cu, Ni, and Pb, which probably reflected the metal emissions and utilization during the early period of industrial development and weapon manufacture during the wars in China. The Pb isotopic analysis showed that the surface and subsurface sediments had lower 206Pb/207Pb and 208Pb/ 207Pb ratios than the deeper layers, reflecting the additional input of Pb from mining activities that took place during the Bronze Age era and in modern times. This study provides direct evidence of the environmental impact of the mining and utilization of metals in the last 7,000 years in one of the important regions of Chinese civilization.

  8. Cooperation control strategies for China's cross-region pollution in a lake basin based on green reduction cost.

    PubMed

    Li, Changmin; Sun, Dong; Xie, Xiaoqiang; Xue, Jian

    2016-05-01

    The cross-region water pollution issue has always been the widespread concern around the world. It becomes especially critical for China due to the imbalance relates to environmental costs that have accompanied rapid growth of economy. Though the government makes great efforts to improve it, the potential for water pollution conflict is still great. We consider the problem of determining combined control strategies for China's cross-region lake pollution based on the environmental green costs. The problem is first formulated as a generalized bilevel mathematical program where the upper level consists in each region that reduces environmental green costs including three parts: the reduction cost, pollution permit trade cost and cost of environment damage, while the lower level is represented by pollution permit equilibrium market. Finally, we take an empirical analysis in Taihu lake. The numerical study shows that the minimum costs of both total and regional are obviously superior to the current processing costs, which provides theoretical basis for the price of emission permits. Today, China's rapid gross domestic product (GDP) growth has come at a very high cost, as real estate prices have skyrocketed, the wealth gap has widened, and environmental pollution has worsened. China's central government is urged to correct the GDP-oriented performance evaluation system that is used to judge administrative region leaders. The cross-region water pollution issue has become a troubling issue that urgently needs to be resolved in China. This paper will not only actively aid efforts to govern Lake Taihu and other cross-region valleys, but it will also provide a supplement for theoretical research on cross-region pollution issues.

  9. 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.

  10. The Dynamics of Microcystis Genotypes and Microcystin Production and Associations with Environmental Factors during Blooms in Lake Chaohu, China

    PubMed Central

    Yu, Li; Kong, Fanxiang; Zhang, Min; Yang, Zhen; Shi, Xiaoli; Du, Mingyong

    2014-01-01

    Lake Chaohu, which is a large, shallow, hypertrophic freshwater lake in southeastern China, has been experiencing lake-wide toxic Microcystis blooms in recent decades. To illuminate the relationships between microcystin (MC) production, the genotypic composition of the Microcystis community and environmental factors, water samples and associated environmental data were collected from June to October 2012 within Lake Chaohu. The Microcystis genotypes and MC concentrations were quantified using quantitative real-time PCR (qPCR) and HPLC, respectively. The results showed that the abundances of Microcystis genotypes and MC concentrations varied on spatial and temporal scales. Microcystis exists as a mixed population of toxic and non-toxic genotypes, and the proportion of toxic Microcystis genotypes ranged from 9.43% to 87.98%. Both Pearson correlation and stepwise multiple regressions demonstrated that throughout the entire lake, the abundances of total and toxic Microcystis and MC concentrations showed significant positive correlation with the total phosphorus and water temperature, suggesting that increases in temperature together with the phosphorus concentrations may promote more frequent toxic Microcystis blooms and higher concentrations of MC. Whereas, dissolved inorganic carbon (DIC) was negatively correlated with the abundances of total and toxic Microcystis and MC concentrations, indicating that rising DIC concentrations may suppress toxic Microcystis abundance and reduce the MC concentrations in the future. Therefore, our results highlight the fact that future eutrophication and global climate change can affect the dynamics of toxic Microcystis blooms and hence change the MC levels in freshwater. PMID:25474494

  11. Lake evolution of the terminal area of Shiyang River drainage in arid China since the last glaciation

    USGS Publications Warehouse

    Shi, Q.; Chen, F.-H.; Zhu, Y.; Madsen, D.

    2002-01-01

    Investigations of geomorphology and sedimentology, and analyses of radiocarbon dates, grain size and carbonate of the sediment at the present-dry closed basin in the terminal area of Shiyang River in arid China were conducted to recover the history of palaeolake change since the last glacial. The terminal area was covered by eolian sand before 13,000 14C BP. Lacustrine deposits covered the eolian sand after 13,000 14C BP, but were succeeded rapidly by eolian or fluvial deposits ca. 11,200-10,000 BP. This fact plus the grain-size distribution and CaCO3 content showed that climate was extremely dry during the last glacial, but wet-dry oscillations characterized the late glacial. A single coalescent lake, over 45 m deep and 2130 km2, formed between 10,000-6400 14C BP in the basin. The lake disintegrated into several shallow carbonate lakes or swamps gradually after 6400 14C BP. Eolian sand reached into the most part of the basin during the period. The lake evolution in the area generally reflects the East Asian summer monsoon history forced by Northern hemisphere insolation. Short time-scale lake fluctuations also existed in the area since the last glacial. ?? 2002 Elsevier Science Ltd and INQUA. All rights reserved.

  12. Risk and toxicity assessments of heavy metals in sediments and fishes from the Yangtze River and Taihu Lake, China.

    PubMed

    Fu, Jie; Hu, Xin; Tao, Xiancong; Yu, Hongxia; Zhang, Xiaowei

    2013-11-01

    Heavy metal pollution is one of the most serous environmental issues globally. To evaluate the metal pollution in Jiangsu Province of China, the total concentrations of heavy metals in sediments and fishes from the Yangtze River and Taihu Lake were analyzed. Ecological risk of sediments and human health risk of fish consumption were assessed respectively. Furthermore, toxicity of samples on expression of the stress responsive genes was evaluated using microbial live cell-array method. The results showed that the heavy metals concentrations in sediments from the Yangtze River were much higher than those in sediments from the Taihu Lake. However, the fishes from the Taihu Lake had higher concentrations of heavy metals than fishes from the Yangtze River. Ecological risk evaluation showed that the heavy metal contaminants in sediments from the Yangtze River posed higher risk of adverse ecological effects, while sediments from the study areas of Taihu Lake were relatively safe. Health risk assessment suggested that the heavy metals in fishes of both Yangtze River and Taihu Lake might have risk of adverse health effects to human. The toxicity assessment indicated that the heavy metals in these sediments and fishes showed transcriptional effects on the selected 21 stress responsive genes, which were involved in the pathways of DNA damage response, chemical stress, and perturbations of electron transport. Together, this field investigation combined with chemical analysis, risk assessment and toxicity bioassay would provide useful information on the heavy metal pollution in Jiangsu Province. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Heavy metal pollution status and ecological risks of sediments under the influence of water transfers in Taihu Lake, China.

    PubMed

    Liu, Jiajia; Wang, Peifang; Wang, Chao; Qian, Jin; Hou, Jun

    2017-01-01

    The effects of water transfer projects on water channels and the receiving water involved need to be understood. In this research, the compositions and particle size distributions of surface sediment and the Cd, Cr, Cu, Ni, Pb, and Zn contents and distributions in the sediment along a water transfer route from the Wangyu River to Taihu Lake, China, were studied. The correlative relationship between the grain size trend and heavy metal content distribution suggested that heavy metals in Wangyu River sediment have affected the heavy metal contents of Taihu Lake sediment through silt and clay migrating in the transferred water. Enrichment factors and potential ecological risk values were calculated. Low levels of potential ecological risks are posed at 20 sampling sites in Taihu Lake, but higher-to-serious risks (potential ecological risk values >275) are posed at all Wangyu River sites. Toxicity of heavy metals (Cd, Cu, Zn, and Ni) in the Wangyu River sediments is more serious than those in the Taihu Lake, but is similar to the entrance of Gonghu Bay. Multivariate statistical analyses (Pearson correlation, cluster, and factor analyses) suggested heavy metals in the study area have many sources, and the relationships between particle migration and heavy metal contents indicated transferring water are likely to lead to adverse ecological risks being posed in Taihu Lake.

  14. Water age prediction and its potential impacts on water quality using a hydrodynamic model for Poyang Lake, China.

    PubMed

    Qi, Hengda; Lu, Jianzhong; Chen, Xiaoling; Sauvage, Sabine; Sanchez-Pérez, José-Miguel

    2016-07-01

    The water quality in Poyang Lake, the largest freshwater lake in China, has deteriorated steadily in recent years and local governments have made efforts to manage the potential eutrophication. In order to investigate the transport and retention processes of dissolved substances, the hydrodynamic model, Environmental Fluid Dynamics Code (EFDC) was applied by using the concept of water age. The simulated results showed agreement with the measured water level, discharge, and inundation area. The water age in Poyang Lake was significantly influenced by the variations of hydrological conditions. The annual analysis revealed that the largest averaged water age was observed during the wet year (2010) with 28.4 days at Hukou, the junction of the Yangtze River and Poyang Lake. In the normal season (April), the youngest age with 9.1 days was found. The spatial distribution of water quality derived from the remote sensing images suggested that a higher chlorophyll-a concentration, lower turbidity, and smaller water age in the eastern area of Poyang Lake might threaten the regional aquatic health. The particle tracking simulation reproduced the trajectories of the dissolved substances, indicating that the water mass with greater nutrient loading would further lead to potential environmental problems in the east lake. Moreover, the water transfer ability would be weakened due to dam (Poyang Project) construction resulting in the rising water levels in periods of regulation. Generally, this study quantified an indicative transport timescale, which could help to better understand the complex hydrodynamic processes and manage wetland ecosystems similar to Poyang Lake.

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

    PubMed

    Sui, Fengyang; 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.

  16. 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.

  17. Trophic magnification and isomer fractionation of perfluoroalkyl substances in the food web of Taihu Lake, China.

    PubMed

    Fang, Shuhong; Chen, Xinwei; Zhao, Shuyan; Zhang, Yifeng; Jiang, Weiwei; Yang, Liping; Zhu, Lingyan

    2014-02-18

    Biomagnification of perfluoroalkyl substances (PFASs) are well studied in marine food webs, but related information in fresh water ecosystem and knowledge on fractionation of their isomers along the food web are limited. The distribution, bioaccumulation, magnification, and isomer fractionation of PFASs were investigated in a food web of Taihu Lake, China. Perfluorooctanesulfonate (PFOS) and perfluorocarboxylates (PFCAs) with longer carbon chain lengths, such as perfluorodecanoate (PFDA) and perfluoroundecanoate (PFUnA), were predominant in organisms, while perfluorohexanoate (PFHxA) and perfluorooctanoate (∑PFOA) contributed more in the water phase. The consistent profile signature of PFOA isomers in water phase with 3M electrochemical fluorination (ECF) products suggests that ECF production of PFOA still exists in China. Linear proportions of PFOA, PFOS and perfluorooctane sulfonamide (PFOSA) in the biota were in the range of 91.9-100%, 78.6-95.5%, and 72.2-95.5%, respectively, indicating preferential bioaccumulation of linear isomers in biota. Trophic magnification factors (TMFs) were estimated for PFDA (2.43), perfluorododecanoate (PFDoA) (2.68) and PFOS (3.46) when all biota were included, suggesting that PFOS and long-chained PFCAs are biomagnified in the fresh water food web. The TMF of PFOS isomers descended in the order: n-PFOS (3.86) > 3+5m-PFOS (3.35) > 4m-PFOS (3.32) > 1m-PFOS (2.92) > m2-PFOS (2.67) > iso-PFOS (2.59), which is roughly identical to their elution order on a FluoroSep-RP Octyl column, suggesting that hydrophobicity may be an important contributor for isomer discrimination in biota.

  18. Contrasting Distributions of Bacterial Branched Tetraethers along a Soil-River-Lake Transect in the Arid Region of Northwestern China

    NASA Astrophysics Data System (ADS)

    Lu, J.

    2016-12-01

    Understanding the transport of branched glycerol dialkyl glycerol tetraethers (brGDGTs) along the soil-river-lake transect is of vital importance, which helps discriminate the autochthonous from allochthonous contribution of brGDGTs in lake and river environment and favors the application of brGDGT-based proxies in paleo-reconstruction. We collected the sediment samples from the Qinghai Lake, the largest saline lake in China, as well as the river sediments and catchment soils, to examine the difference in the distribution of 5- vs. 6-methyl brGDGTs along the soil-river-lake transect. The brGDGT distributions were found to show a large variation along the transect, which can be reflected by the MBT'-derived indices and IR (isomer ratio) indices. There is a considerable difference in brGDGT distributions between soil and the river sediment. The inflowing rivers likely receive terrestrial brGDGT input to a variable degree. BrGDGTs in the Buha river are primarily of autochthonous origin whereas other ephemeral streams, like the Heima river, exhibit a similar brGDGT distribution to the surrounding soils, reflecting that these compounds are likely derived from soils. A higher quantity of 6-methyl brGDGTs and brGDGT-Ia was observed in the lake than in the river sediments, pointing to a preferential degradation of 5-methyl brGDGTs and/or an increase of in situ production of 6-methyl brGDGTs in the lake. Besides the difference in brGDGT distributions caused by the transportation and in situ production along the transect, we also identified the difference caused by several driving factors in different environments. In arid and alkaline soils, both CBT' and IR indices have strong correlations with soil pH even within the narrow pH range. However, we find a clear relationship of CBT with water salinity in Buha river. The difference in soil and river leads to a complicated interpretation for the CBT (CBT') index. In the lake, the MBT' (specially represented by MBT'5ME and MBT'6

  19. Distribution, fractionation and risk assessment of mercury in surficial sediments of Nansi Lake, China.

    PubMed

    Zhang, Wei; Cao, Feifei; Yang, Liyuan; Dai, Jierui; Pang, Xugui

    2017-03-01

    Nansi Lake is composed of four sub-lakes from north to south: Nanyang Lake, Dushan Lake, Zhaoyang Lake and Weishan Lake. An environmental pollution investigation was carried out to determine the fractionation, and pollution assessments of mercury (Hg) in surficial sediments from Nansi Lake. Results showed that the mean concentration of Hg was 3.1 times higher than its background value (0.015 mg kg(-1)), and the high concentration of Hg which even reached up to five times than the background value in the part of Dushan Lake and Weishan Lake, which indicated that there are obvious spatial differences. The content of Hg was positively correlated with that of total organic carbon, and negatively correlated with that of pH and SiO2 in surface sediments. An improved Tessier sequential extraction procedure was used to study the fractions of Hg in sediments. The results indicated that Hg existed primarily in the fraction of residual, which accounts for 58.4% of total mercury (THg), and the percentage of extractable Hg was only 1.93% of total mercury. High concentrations of mercury of non-residual phase were found in part lake area from the Nanyang Lake and the Weishan Lake, which indicating a higher potential ecological risk relative to the other lake areas. Based on the values of enrichment factor and geo-accumulation index, most part of Dushan Lake and Nanyang Lake and Weishan Lake were in a moderate pollution. And based on the fractionation of mercury, risk assessment code of Hg exhibited low risks to the environment in Nansi Lake.

  20. 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

  1. 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.

  2. Novel acsF Gene Primers Revealed a Diverse Phototrophic Bacterial Population, Including Gemmatimonadetes, in Lake Taihu (China)

    PubMed Central

    Zeng, Yanhua; Lu, Hang; Feng, Hao; Zeng, Yonghui

    2016-01-01

    ABSTRACT Anoxygenic phototrophs represent an environmentally important and phylogenetically diverse group of organisms. They harvest light using bacteriochlorophyll-containing reaction centers. Recently, a novel phototrophic bacterium, Gemmatimonas phototrophica, belonging to a rarely studied phylum, Gemmatimonadetes, was isolated from a freshwater lake in the Gobi Desert. To obtain more information about the environmental distribution of phototrophic Gemmatimonadetes, we collected microbial samples from the water column, upper sediment, and deeper anoxic sediment of Lake Taihu, China. MiSeq sequencing of the 16S rRNA, pufM, and bchY genes was carried out to assess the diversity of local phototrophic communities. In addition, we designed new degenerate primers of aerobic cyclase gene acsF, which serves as a convenient marker for both phototrophic Gemmatimonadetes and phototrophic Proteobacteria. Our results showed that most of the phototrophic species in Lake Taihu belong to Alpha- and Betaproteobacteria. Sequences of green sulfur and green nonsulfur bacteria (phototrophic Chlorobi and Chloroflexi, respectively) were found in the sediment. Using the newly designed primers, we identified a diverse community of phototrophic Gemmatimonadetes forming 30 operational taxonomic units. These species represented 10.5 and 17.3% of the acsF reads in the upper semiaerobic sediment and anoxic sediment, whereas their abundance in the water column was <1%. IMPORTANCE Photosynthesis is one of the most fundamental biological processes on Earth. Recently, the presence of photosynthetic reaction centers has been reported from a rarely studied bacterial phylum, Gemmatimonadetes, but almost nothing is known about the diversity and environmental distribution of these organisms. The newly designed acsF primers were used to identify phototrophic Gemmatimonadetes from planktonic and sediment samples collected in Lake Taihu, China. The Gemmatimonadetes sequences were found mostly in the

  3. Asticcacaulis taihuensis sp. nov., a novel stalked bacterium isolated from Taihu Lake, China.

    PubMed

    Liu, Zhi-Pei; Wang, Bao-Jun; Liu, Shuang-Jiang; Liu, Ying-Hao

    2005-05-01

    A novel stalked bacterium, designated strain T3-B7(T), was isolated from sediment of Taihu Lake, Jiangsu Province, China, and its taxonomy was studied by using a polyphasic approach. Cell morphology, physiological and biochemical properties, and polar lipids indicated that strain T3-B7(T) represented a member of the genus Asticcacaulis. Based on 16S rRNA gene sequence similarity analysis, strain T3-B7(T) was found to be phylogenetically related to Asticcacaulis biprosthecium DSM 4723(T) (98.5 %) and Asticcacaulis excentricus DSM 4724(T) (95.0 %), but could be differentiated from these two species on the basis of the number and position of prosthecae, assimilation of sugars, nitrate reduction and tolerance to NaCl. Levels of DNA-DNA relatedness of strain T3-B7(T) to A. biprosthecium DSM 4723(T) and A. excentricus DSM 4724(T) were 37.1 and 18.0 %, respectively. The G + C content of strain T3-B7(T) was 59 mol% (T(m)). It is concluded that strain T3-B7(T) represents a novel species of the genus Asticcacaulis, for which the name of Asticcacaulis taihuensis sp. nov. is proposed. The type strain is T3-B7(T) (=AS 1.3431(T) = JCM 12463(T)).

  4. Halorientalis brevis sp. nov., Isolated from an Inland Salt Lake of China.

    PubMed

    Yuan, Pan-Pan; Yin, Shuai; Han, Dong; Zhang, Wen-Jiao; Cui, Heng-Lin

    2015-09-01

    Halophilic archaeal strain YC89(T) was isolated from Yuncheng salt lake in Shanxi, China. Cells from strain YC89(T) were short rods, lysed in distilled water, stained Gram-negative and formed red-pigmented colonies on agar plate. Strain YC89(T) was able to grow at 25-50°C (optimum 37°C), at 1.4-4.8 M NaCl (optimum 2.6-3.1 M), at 0-1.0 M MgCl2 (optimum 0.3 M) and at pH 6.0-9.5 (optimum pH 7.5). The major polar lipids are phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, sulfated mannosyl glucosyl diether and two unknown glycolipids. 16S rRNA gene analysis revealed that strain YC89(T) was phylogenetically related to Halorientalis persicus D108(T) (95.6% nucleotide identity) and H. regularis TNN28(T) (95.3% nucleotide identity). The rpoB' gene similarities between strain YC89(T) and H. persicus IBRC-M 10043(T) and H. regularis TNN28(T) were 88.1 and 88.0%, respectively. The DNA G+C content of strain YC89(T) was determined to be 61.3 mol%. The phenotypic, chemotaxonomic and phylogenetic properties suggested that strain YC89(T) (=CGMCC 1.12125(T) = JCM 18366(T)) represents a new species of Halorientalis, for which the name H. brevis sp. nov. is proposed.

  5. Genetic structure of duckweed population of Spirodela, Landoltia and Lemna from Lake Tai, China.

    PubMed

    Tang, Jie; Zhang, Fei; Cui, Weihua; Ma, Jiong

    2014-06-01

    Duckweed is widely used in environmental biotechnology and has recently emerged as a potential feedstock for biofuels due to its high growth rate and starch content. The genetic diversity and composition of a natural duckweed population in genera Spirodela, Landoltia and Lemna from Lake Tai, China, were investigated using probabilistic analysis of multilocus sequence typing (MLST). The 78 strains were categorized into five lineages, among which strains representing L. aequinoctialis and S. polyrhiza were predominant. Among the five lineages, interlineage transfers of markers were infrequent and no recombination was statistically detected. Tajima's D tests determined that all loci are subject to population bottlenecks, which is likely one of the main reasons for the low genetic diversity observed within the lineages. Interestingly, strains of L. turionifera are found to contain small admixture from L. minor, providing rare evidence of transfer of genetic materials in duckweed. This was discussed with respect to the hypothesis that a cross of these two gave rise to L. japonica. Moreover, the conventional maximum-likelihood phylogenetic analysis clearly recognized all the species in the three genera with high bootstrap supports. In conclusion, this work offers a basic framework for using MLST to characterize Spirodela, Landoltia and in particular Lemna strains at the species level, and to study population genetics and evolution history of natural duckweed populations.

  6. Spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in sediments of the Nansi Lake, China.

    PubMed

    Li, Hong-Li; Gao, Hong; Zhu, Chen; Li, Guo-Gang; Yang, Fan; Gong, Zheng-Yu; Lian, Jun

    2009-07-01

    Polycyclic aromatic hydrocarbons (PAHs) were measured in surface sediments and dated core sediments from the Nansi Lake of China to investigate the spatial and temporal distribution characteristics. The concentrations of 16 kinds priority PAH compounds were determined by GC-MS method. And (210)Pb isotope dating method was used to determine the chronological age of the sediment as well as the deposition rate. The results indicated that the total PAHs concentration ranges in surface and core sediment samples were 160 approximately 32,600 and 137 approximately 693 ng/g (dry wt.), respectively. The sediment rate and the average mass sedimentation were calculated to be 0.330 cm x year(-1) and 0.237 g x cm(-2) x yr(-1) and the sediment time of the collected core sample ranged from 1899 to 2000. The peak of PAH concentrations came at recent years. The source analysis showed PAHs mainly came from the contamination of low temperature pyrogenic processes, such as coal combustion. The PAHs concentrations were lower than ERL and LEL values for most collected samples. However, in several surface sediment samples especially in estuary sites, the PAHs concentrations were not only higher than ERL and LEL values, but also higher than ERM values.

  7. Effects of Nutrients, Temperature and Their Interactions on Spring Phytoplankton Community Succession in Lake Taihu, China

    PubMed Central

    Deng, Jianming; Qin, Boqiang; Paerl, Hans W.; Zhang, Yunlin; Wu, Pan; Ma, Jianrong; Chen, Yuwei

    2014-01-01

    We examined the potential effects of environmental variables, and their interaction, on phytoplankton community succession in spring using long-term data from 1992 to 2012 in Lake Taihu, China. Laboratory experiments were additionally performed to test the sensitivity of the phytoplankton community to nutrient concentrations and temperature. A phytoplankton community structure analysis from 1992 to 2012 showed that Cryptomonas (Cryptophyta) was the dominant genus in spring during the early 1990s. Dominance then shifted to Ulothrix (Chlorophyta) in 1996 and 1997. However, Cryptomonas again dominated in 1999, 2000, and 2002, with Ulothrix regaining dominance from 2003 to 2006. The bloom-forming cyanobacterial genus Microcystis dominated in 1995, 2001 and 2007–2012. The results of ordinations indicated that the nutrient concentration (as indicated by the trophic state index) was the most important factor affecting phytoplankton community succession during the past two decades. In the laboratory experiments, shifts in dominance among phytoplankton taxa occurred in all nutrient addition treatments. Results of both long term monitoring and experiment indicated that nutrients exert a stronger control than water temperature on phytoplankton communities during spring. Interactive effect of nutrients and water temperature was the next principal factor. Overall, phytoplankton community composition was mediated by nutrients concentrations, but this effect was strongly enhanced by elevated water temperatures. PMID:25464517

  8. Effects of nutrients, temperature and their interactions on spring phytoplankton community succession in Lake Taihu, China.

    PubMed

    Deng, Jianming; Qin, Boqiang; Paerl, Hans W; Zhang, Yunlin; Wu, Pan; Ma, Jianrong; Chen, Yuwei

    2014-01-01

    We examined the potential effects of environmental variables, and their interaction, on phytoplankton community succession in spring using long-term data from 1992 to 2012 in Lake Taihu, China. Laboratory experiments were additionally performed to test the sensitivity of the phytoplankton community to nutrient concentrations and temperature. A phytoplankton community structure analysis from 1992 to 2012 showed that Cryptomonas (Cryptophyta) was the dominant genus in spring during the early 1990s. Dominance then shifted to Ulothrix (Chlorophyta) in 1996 and 1997. However, Cryptomonas again dominated in 1999, 2000, and 2002, with Ulothrix regaining dominance from 2003 to 2006. The bloom-forming cyanobacterial genus Microcystis dominated in 1995, 2001 and 2007-2012. The results of ordinations indicated that the nutrient concentration (as indicated by the trophic state index) was the most important factor affecting phytoplankton community succession during the past two decades. In the laboratory experiments, shifts in dominance among phytoplankton taxa occurred in all nutrient addition treatments. Results of both long term monitoring and experiment indicated that nutrients exert a stronger control than water temperature on phytoplankton communities during spring. Interactive effect of nutrients and water temperature was the next principal factor. Overall, phytoplankton community composition was mediated by nutrients concentrations, but this effect was strongly enhanced by elevated water temperatures.

  9. Halobacterium jilantaiense sp. nov., a halophilic archaeon isolated from a saline lake in Inner Mongolia, China.

    PubMed

    Yang, Yong; Cui, Heng-Lin; Zhou, Pei-Jin; Liu, Shuang-Jiang

    2006-10-01

    A novel halophilic archaeon, NG4(T), was isolated from Jilantai salt lake in Inner Mongolia, China. The taxonomy of strain NG4(T) was studied by polyphasic methods. Strain NG4(T) grew at pH 5.5-8.5 and at a temperature of 22-55 degrees C. It was chemo-organotrophic, aerobic and required concentrations of 2.7-5.2 M NaCl and 0.05-0.3 M Mg(2+) for growth. Cells were Gram-negative, slender rods. Colonies on agar plates containing 25 % (w/v) total salts were red, elevated and round. According to 16S rRNA gene sequence similarity, strain NG4(T) was phylogenetically related to Halobacterium salinarum DSM 3754(T) (98.2 %) and Halobacterium noricense A1(T) (97.3 %). The DNA G+C content was 64.2 mol%. DNA-DNA relatedness values with Hbt. salinarum DSM 3754(T) and Hbt. noricense A1(T) were 47 and 35 %, respectively. The polar lipids of strain NG4(T) consisted of phosphatidylglycerol, methylated phosphatidylglycerol phosphate, phosphatidylglycerol sulfate, triglycosyl diether, sulfated triglycosyl diether and sulfated tetraglycosyl diether. It was concluded that strain NG4(T) represents a novel species of the genus Halobacterium, for which the name Halobacterium jilantaiense sp. nov. is proposed. The type strain is NG4(T) (=CGMCC 1.5337(T)=JCM 13558(T)).

  10. 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.

  11. Nitrogen export from an agriculture watershed in the Taihu Lake area, China.

    PubMed

    Gao, C; Zhu, J G; Zhu, J Y; Gao, X; Dou, Y J; Hosen, Y

    2004-01-01

    Temporal changes in nitrogen concentrations and stream discharge, as well as sediment and nitrogen losses from erosion plots with different land uses, were studied in an agricultural watershed in the Taihu Lake area in eastern China. The highest overland runoff loads and nitrogen losses were measured under the upland at a convergent footslope. Much higher runoff, sediment and nitrogen losses were observed under upland cropping and vegetable fields than that under chestnut orchard and bamboo forest. Sediment associated nitrogen losses accounted for 8-43.5% of total nitrogen export via overland runoff. N lost in dissolved inorganic nitrogen forms (NO(3-)-N + NH4+-N) accounted for less than 50% of total water associated nitrogen export. Agricultural practices and weather-driven fluctuation in discharge were main reasons for the temporal variations in nutrient losses via stream discharge. Significant correlation between the total nitrogen concentration and stream discharge load was observed. Simple regression models could give satisfactory results for prediction of the total nitrogen concentrations in stream water and can be used for better quantifying nitrogen losses from arable land. Nitrogen losses from the studied watershed via stream discharge during rice season in the year 2002 were estimated to be 10.5 kg N/ha using these simple models.

  12. Cyanobacterial bloom management through integrated monitoring and forecasting in large shallow eutrophic Lake Taihu (China).

    PubMed

    Qin, Boqiang; Li, Wei; Zhu, Guangwei; Zhang, Yunlin; Wu, Tingfeng; Gao, Guang

    2015-04-28

    The large shallow eutrophic Lake Taihu in China has long suffered from eutrophication and toxic cyanobacterial blooms. Despite considerable efforts to divert effluents from the watershed, the cyanobacterial blooms still reoccur and persist throughout summer. To mitigate cyanobacterial bloom pollution risk, a large scale integrated monitoring and forecasting system was developed, and a series of emergency response measures were instigated based on early warning. This system has been in place for 2009-2012. With this integrated monitoring system, it was found that the detectable maximum and average cyanobacterial bloom area were similar to that before drinking water crisis, indicating that poor eutrophic status and cyanobacterial bloom had persisted without significant alleviation. It also revealed that cyanobacterial bloom would occur after the intense storm, which may be associated with the increase in buoyance of cyanobacterial colonies. Although the cyanobacterial blooms had persisted during the monitoring period, there had been a reduction in frequency and intensity of the cyanobacterial bloom induced black water agglomerates (a phenomenon of algal bloom death decay to release a large amount black dissolved organic matter), and there have been no further drinking water crises. This monitoring and response strategy can reduce the cyanobacterial bloom pollution risk, but cannot reduce eutrophication and cyanobacterial blooms, problems which will take decades to resolve. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Risk Factors for Infectious Diseases in Backyard Poultry Farms in the Poyang Lake Area, China

    PubMed Central

    Wang, Yong; Jiang, Zhiben; Jin, Zhenyu; Tan, Hua; Xu, Bing

    2013-01-01

    Emergence and transmission of infectious diseases have an enormous impact on the poultry industry and present a serious threat to the health of humans and wild birds. Noncommercial poultry operations, such as backyard poultry facilities in China, are potential sources of virus exchange between commercial poultry and wild birds. It is particularly critical in wetland areas where backyard poultry have close contact with commercial poultry and migratory birds, therefore increasing the risk of contracting infectious diseases. To evaluate the transmission risks, a cross-sectional study was undertaken in the Poyang Lake area, China, involving 309 residents in the backyard poultry farms in three counties (Region A, B, and C) of Jiangxi Province. We examined the backyard poultry population, poultry species, presence of poultry deaths from infectious diseases, food sources, and biosecurity practices. Region B ranked highest for biosecurity while region C ranked lowest. The risks of infectious diseases were assessed by adjusted odds ratio based on multivariate logistic regression analysis. Potential risk factors in the three regions of the study site were compared. In Region A, significant factor was contact of poultry with wild birds (OR: 6.573, 95% CI: 2.148–20.115, P=0.001). In Region B, the most significant factor was contact of poultry with neighboring backyard waterfowls (OR: 3.967, 95% CI: 1.555–10.122, P=0.004). In Region C, significant factors were poultry purchase from local live bird markets (OR: 3.740, 95% CI: 1.243–11.255, P=0.019), and contact of poultry with wild birds (OR: 3.379, 95% CI: 1.058–10.791, P=0.040). In summary, backyard poultry was significantly affected by neighboring commercial poultry and close contact with wild birds. The results are expected to improve our understanding of the transmission risks of infectious diseases in a typical backyard poultry environment in rural China, and address the need to improve local farming practices and

  14. Aquatic biogeochemistry: Cleaner Chinese lakes

    NASA Astrophysics Data System (ADS)

    Corman, Jessica

    2017-07-01

    Phosphorus loading can cause eutrophication of lakes. Analyses of lake chemistry in China reveal that policies have led to lower phosphorus levels overall, but increasing trends in some lakes suggest that expanded policies may be needed.

  15. 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

  16. Practical success of biomanipulation using filter-feeding Fish to control cyanobacteria blooms: a synthesis of decades of research and application in a subtropical hypereutrophic lake.

    PubMed

    Xie, P; Liu, J

    2001-08-08

    Lake Donghu is a 32-km2 shallow, subtropical lake near the Yangtze River (P.R. China) that has experienced dramatic changes in the past five decades. These changes include: (1) a trophic state change from mesotrophy to hypertrophy; (2) dense blooms of cyanobacteria during every summer from the 1970s to 1984; (3) a cessation of blooms starting in 1985, with no recurrence; and (4) an increase, coincident with bloom declines, in the production of silver and bighead carp (filter-feeders) by more than tenfold. There are several possible explanations for the disappearance of blooms, including changes in nutrient concentrations, increased zooplankton grazing, and increased grazing on algae by fish. The long-term data suggest that changes in nutrients or in zooplankton were not important, but that the remarkably increased fish densities might have played the key role. To test this hypothesis, in situ enclosure experiments were conducted in three years. The main conclusions are as follows: (1) an increased stocking of the lake with carp played a decisive role in the elimination of cyanobacteria blooms; (2) both silver and bighead carp can eliminate cyanobacteria blooms directly by grazing; (3) zooplankton cannot suppress the blooms; and (4) the lake still is vulnerable to the outbreak of blooms, should fish grazing decline. The critical biomass of carp is approximately 50 g m3. The results suggest the applicability of a new food-web manipulation (increased stocking with filter-feeding fish) for controlling cyanobacteria blooms in hypereutrophic lakes. The approach differs from traditional biomanipulation in Europe and North America, where piscivores are added to control planktivores, and this in turn increases zooplankton and decreases algae. The new biomanipulation method is being used or being tested to counteract cyanobacteria blooms in many Chinese lakes such as Lake Dianchi in Yunnan Province, Lake Chaohu in Anhui Province, and Lake Taihu in Jiangsu Province. The

  17. Using dual isotopes to evaluate sources and transformations of nitrate in the West Lake watershed, eastern China.

    PubMed

    Jin, Zanfang; Qin, Xue; Chen, Lingxiao; Jin, Mantong; Li, Feili

    2015-01-01

    The West Lake is a World Heritage site in the West Lake watershed in eastern China. In this study, the hydrogeological and dual isotopic approaches were integrated to evaluate the seasonal and spatial variations of nitrate (NO3(-)) in the West Lake watershed, and to characterize NO3(-) sources and transformations. The results revealed that the geochemical facies of the water samples were dominated by Ca(2+)+Na(+)-HCO3(-)+SO4(2)(-) in the surface water and transfer water, Ca(2+)+Na(+)-HCO3(-) and Ca(2+)+Na(+)-SO4(2-) in the groundwater, which most likely reflect natural reactions and anthropogenic inputs. About 13% of the groundwater samples containing NO3(-) exceeded the World Health Organization (WHO) standard of 10 mg N L(-1). NO3(-) was the dominant form of total nitrogen (TN) and was the main surface water contaminant in the West Lake watershed. The δ(15)NNO3 and δ(18)ONO3 values indicated that the dominant NO3(-) sources in surface water were soil nitrogen (soil N) and chemical fertilizers, while the main NO3(-) sources in groundwater were soil N from the forest, chemical fertilizers and manure in the tea garden, domestic sewage from the small, old residential area in the forest as well as urban areas. The distribution of NO3(-) in groundwater was strongly influenced by land use. Results also suggest that there was significant nitrification in surface water and groundwater in the West Lake watershed, and that there were also denitrification processes in groundwater. The annual net fluxes of TN, NO3(-), and NH4(+) into the West Lake were 2.0×10(4), 4.0×10(3), and 1.31×10(4) kg as N, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Using dual isotopes to evaluate sources and transformations of nitrate in the West Lake watershed, eastern China

    NASA Astrophysics Data System (ADS)

    Jin, Zanfang; Qin, Xue; Chen, Lingxiao; Jin, Mantong; Li, Feili

    2015-06-01

    The West Lake is a World Heritage site in the West Lake watershed in eastern China. In this study, the hydrogeological and dual isotopic approaches were integrated to evaluate the seasonal and spatial variations of nitrate (NO3-) in the West Lake watershed, and to characterize NO3- sources and transformations. The results revealed that the geochemical facies of the water samples were dominated by Ca2 + + Na+-HCO3- + SO42- in the surface water and transfer water, Ca2 + + Na+-HCO3- and Ca2 + + Na+-SO42 - in the groundwater, which most likely reflect natural reactions and anthropogenic inputs. About 13% of the groundwater samples containing NO3- exceeded the World Health Organization (WHO) standard of 10 mg N L- 1. NO3- was the dominant form of total nitrogen (TN) and was the main surface water contaminant in the West Lake watershed. The δ15NNO3 and δ18ONO3 values indicated that the dominant NO3- sources in surface water were soil nitrogen (soil N) and chemical fertilizers, while the main NO3- sources in groundwater were soil N from the forest, chemical fertilizers and manure in the tea garden, domestic sewage from the small, old residential area in the forest as well as urban areas. The distribution of NO3- in groundwater was strongly influenced by land use. Results also suggest that there was significant nitrification in surface water and groundwater in the West Lake watershed, and that there were also denitrification processes in groundwater. The annual net fluxes of TN, NO3-, and NH4+ into the West Lake were 2.0 × 104, 4.0 × 103, and 1.31 × 104 kg as N, respectively.

  19. A model to determine the lake nutrient standards for drinking water sources in Yunnan-Guizhou Plateau Ecoregion, China.

    PubMed

    Ji, Danfeng; Xi, Beidou; Su, Jing; Huo, Shouliang; He, Li; Liu, Hongliang; Yang, Queping

    2013-09-01

    Lake eutrophication (LE) has become an increasingly severe environmental problem recently. However, there has been no nutrient standard established for LE control in many developing countries such as China. This study proposes a structural equation model to assist in the establishment of a lake nutrient standard for drinking water sources in Yunnan-Guizhou Plateau Ecoregion (Yungui Ecoregion), China. The modeling results indicate that the most predictive indicator for designated use-attainment is total phosphorus (TP) (total effect = -0.43), and chlorophyll a (Chl-a) is recommended as the second important indicator (total effect = -0.41). The model is further used for estimating the probability of use-attainment associated with lake water as a drinking water source and various levels of candidate criteria (based on the reference conditions and the current environmental quality standards for surface water). It is found that these candidate criteria cannot satisfy the designated 100% use-attainment. To achieve the short-term target (85% attainment of the designated use), TP and Chl-a values ought to be less than 0.02 mg/L and 1.4 microg/L, respectively. When used as a long-term target (90% or greater attainment of the designated use), the TP and Chl-a values are suggested to be less than 0.018 mg/L and 1 microg/L, respectively.

  20. 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.

  1. 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.

  2. Responses of landscape pattern of China's two largest freshwater lakes to early dry season after the impoundment of Three-Gorges Dam

    NASA Astrophysics Data System (ADS)

    Wu, Haipeng; Zeng, Guangming; Liang, Jie; Chen, Jin; Xu, Jijun; Dai, Juan; Sang, Lianhai; Li, Xiaodong; Ye, Shujing

    2017-04-01

    The effects of hydrologic cycle change (caused by human activity and global climate change) on ecosystems attract the increasing attention around the world. As a result of impounding of the Three Gorges Dam (TGD), climate change and sand mining, the dry season of Poyang Lake and Dongting Lake (China's two largest freshwater lakes) came early after the TGD impoundment. It was the primary cause of the increasing need for sluice/dam construction to store water in the Lakes and attracted increasing attention. In this paper, we compared the landscape pattern between three hydrologic years with early dry season (EY) and three normal hydrologic years (NY) of each lake by remote sensing technology, to reveal the effect of early dry season on landscape pattern. The results showed that early dry season caused expanding of Phalaris to mudflat zone in Poyang Lake, while caused expanding of Carex to Phalaris zone and expanding of Phalaris to mudflat zone in Dongting Lake. In landscape level, there was no significant difference in landscape grain size, landscape grain shape, habitat connectivity and landscape diversity between EY and NY in the two lakes. While in habitat class level, there were significant changes in area of mudflat and Phalaris and grain size of mudflat in Poyang Lake, and in area of Carex, grain size of Phalaris and grain shape of Carex and Phalaris in Dongting Lake. These changes will impact migrating birds of East Asian and migratory fishes of Yangtze River.

  3. 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

  4. Effects of abiotic factors on ecosystem health of Taihu Lake, China based on eco-exergy theory

    PubMed Central

    Wang, Ce; Bi, Jun; Fath, Brian D.

    2017-01-01

    A lake ecosystem is continuously exposed to environmental stressors with non-linear interrelationships between abiotic factors and aquatic organisms. Ecosystem health depicts the capacity of system to respond to external perturbations and still maintain structure and function. In this study, we explored the effects of abiotic factors on ecosystem health of Taihu Lake in 2013, China from a system-level perspective. Spatiotemporal heterogeneities of eco-exergy and specific eco-exergy served as thermodynamic indicators to represent ecosystem health in the lake. The results showed the plankton community appeared more energetic in May, and relatively healthy in Gonghu Bay with both higher eco-exergy and specific eco-exergy; a eutrophic state was likely discovered in Zhushan Bay with higher eco-exergy but lower specific eco-exergy. Gradient Boosting Machine (GBM) approach was used to explain the non-linear relationships between two indicators and abiotic factors. This analysis revealed water temperature, inorganic nutrients, and total suspended solids greatly contributed to the two indicators that increased. However, pH rise driven by inorganic carbon played an important role in undermining ecosystem health, particularly when pH was higher than 8.2. This implies that climate change with rising CO2 concentrations has the potential to aggravate eutrophication in Taihu Lake where high nutrient loads are maintained. PMID:28220835

  5. 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.

  6. Effects of abiotic factors on ecosystem health of Taihu Lake, China based on eco-exergy theory.

    PubMed

    Wang, Ce; Bi, Jun; Fath, Brian D

    2017-02-21

    A lake ecosystem is continuously exposed to environmental stressors with non-linear interrelationships between abiotic factors and aquatic organisms. Ecosystem health depicts the capacity of system to respond to external perturbations and still maintain structure and function. In this study, we explored the effects of abiotic factors on ecosystem health of Taihu Lake in 2013, China from a system-level perspective. Spatiotemporal heterogeneities of eco-exergy and specific eco-exergy served as thermodynamic indicators to represent ecosystem health in the lake. The results showed the plankton community appeared more energetic in May, and relatively healthy in Gonghu Bay with both higher eco-exergy and specific eco-exergy; a eutrophic state was likely discovered in Zhushan Bay with higher eco-exergy but lower specific eco-exergy. Gradient Boosting Machine (GBM) approach was used to explain the non-linear relationships between two indicators and abiotic factors. This analysis revealed water temperature, inorganic nutrients, and total suspended solids greatly contributed to the two indicators that increased. However, pH rise driven by inorganic carbon played an important role in undermining ecosystem health, particularly when pH was higher than 8.2. This implies that climate change with rising CO2 concentrations has the potential to aggravate eutrophication in Taihu Lake where high nutrient loads are maintained.

  7. 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.

  8. An ecological risk assessment of heavy metal contamination in the surface sediments of Bosten Lake, northwest China.

    PubMed

    Mamat, Zulpiya; Haximu, Sadiguli; Zhang, Zhao Yong; Aji, Rouzi

    2016-04-01

    Bosten Lake, a typical rump lake in an oasis in northwest China, was chosen to evaluate the distribution, sources, pollution status, and potential ecological risk of heavy metals. Sediment samples were collected from the lake, and results showed that the values of the eight heavy metals all fell within the Second Soil National Standard, while the average and maximum values of the metals were higher than the background values of the study. Multivariate statistical analysis showed that sediment concentrations of Cd, Pb, Hg, and Zn were mainly influenced by man sources. In comparison, Cu, Ni, Cr, and As were primarily natural in origin. Enrichment factor analysis (EF) and the geo-accumulation index evaluation method (I geo) showed that Cd, Hg, and Pb fell under low and partial serious pollution levels, while Zn, As, Cr, Ni, and Cu mainly were characterized under no pollution and low pollution levels. The potential ecological hazards index (RI) showed that among the eight heavy metals, Pb, Hg, and Cd posed the highest potential ecological risk, with potential ecological hazards indices (RI) of 29.06, 27.71, and 21.54 %, respectively. These findings demonstrated that recent economic development in the area of the basin has led to heavy metal accumulation in the surface sediments of the lake.

  9. Effects of abiotic factors on ecosystem health of Taihu Lake, China based on eco-exergy theory

    NASA Astrophysics Data System (ADS)

    Wang, Ce; Bi, Jun; Fath, Brian D.

    2017-02-01

    A lake ecosystem is continuously exposed to environmental stressors with non-linear interrelationships between abiotic factors and aquatic organisms. Ecosystem health depicts the capacity of system to respond to external perturbations and still maintain structure and function. In this study, we explored the effects of abiotic factors on ecosystem health of Taihu Lake in 2013, China from a system-level perspective. Spatiotemporal heterogeneities of eco-exergy and specific eco-exergy served as thermodynamic indicators to represent ecosystem health in the lake. The results showed the plankton community appeared more energetic in May, and relatively healthy in Gonghu Bay with both higher eco-exergy and specific eco-exergy; a eutrophic state was likely discovered in Zhushan Bay with higher eco-exergy but lower specific eco-exergy. Gradient Boosting Machine (GBM) approach was used to explain the non-linear relationships between two indicators and abiotic factors. This analysis revealed water temperature, inorganic nutrients, and total suspended solids greatly contributed to the two indicators that increased. However, pH rise driven by inorganic carbon played an important role in undermining ecosystem health, particularly when pH was higher than 8.2. This implies that climate change with rising CO2 concentrations has the potential to aggravate eutrophication in Taihu Lake where high nutrient loads are maintained.

  10. Long-Term Study of the Relationship between Precipitation and Aquatic Vegetation Succession in East Taihu Lake, China.

    PubMed

    Zhang, Yehui; Yang, Na; Xu, Jiawei; Yin, Yixing

    2017-01-01

    Based on long-term rainfall measurements (1956-2012), water level records (1956-2006), and aquatic plants field survey data (1960-2014), the relationship between precipitation and aquatic vegetation succession in east Taihu Lake, China, is studied. Neither abrupt changes nor any trends were found in the annual rainfall series in Taihu Lake during the studied period (1956-2012). However, for seasonal variations, statistically significant decreases are found in spring and autumn, while the rainfall in winter exhibits statistically significant increase. No significant trend was obtained in summer. A "dry" period was detected in our studied period (1963/1964~1978/1979). Total annual rainfall was significantly positively correlated to the number of rain-days (r = 0.59) and the water level (r = 0.84). Our results indicate that the variations of rainfall and water level may have an impact on the aquatic plants in Taihu Lake. The dry period may be not suitable for the growth of the aquatic plants. All aquatic plants in Taihu Lake were dramatically reduced in the dry period, especially for submerged macrophytes and floating-leaf macrophytes. Our results may be helpful for the aquatic restoration in the future.

  11. Spatio-temporal Distribution and Chemical Speciation of Iron and Manganese in Sediments from Lake Aha, China

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Hu, Jiwei; Qin, Fanxin; Jiang, Cuihong; Huang, Xianfei; Deng, Jiajun; Li, Cunxiong

    2010-11-01

    This paper reports an investigation on pollution and potential risk on elements of iron (Fe) and manganese (Mn) in sediments from Lake Aha, which is a drinking-water source for Guiyang City, the capital of Guizhou Province in southwestern China. In the present research, chemical speciation of Fe and Mn in sediments from the lake was studied based on the sequential extraction procedure developed by Tessier et al.. The results obtained from the study are as follows. The average values of total Fe were 47617 mg/kg and 70325 mg/kg in sediments from the lake in summer and winter respectively, and its speciation consisted mainly of residual and Fe-Mn oxides fractions. The amounts of total Fe and the distribution of its speciation in the sediments should be affected by effluents from a large quantity of deserted coal mines in the lake basin in summer and winter. The average values of total Mn were 7996 mg/kg and 1753 mg/kg in summer and winter respectively, and its speciation is primarily comprised of carbonate and Fe-Mn oxides fractions. The amounts of total Mn and its distribution in different fractions in the sediments were believed to be primarily influenced by effluents from those deserted coal mines in summer and by the condition of redox interface in winter.

  12. Long-Term Study of the Relationship between Precipitation and Aquatic Vegetation Succession in East Taihu Lake, China

    PubMed Central

    Xu, Jiawei; Yin, Yixing

    2017-01-01

    Based on long-term rainfall measurements (1956–2012), water level records (1956–2006), and aquatic plants field survey data (1960–2014), the relationship between precipitation and aquatic vegetation succession in east Taihu Lake, China, is studied. Neither abrupt changes nor any trends were found in the annual rainfall series in Taihu Lake during the studied period (1956–2012). However, for seasonal variations, statistically significant decreases are found in spring and autumn, while the rainfall in winter exhibits statistically significant increase. No significant trend was obtained in summer. A “dry” period was detected in our studied period (1963/1964~1978/1979). Total annual rainfall was significantly positively correlated to the number of rain-days (r = 0.59) and the water level (r = 0.84). Our results indicate that the variations of rainfall and water level may have an impact on the aquatic plants in Taihu Lake. The dry period may be not suitable for the growth of the aquatic plants. All aquatic plants in Taihu Lake were dramatically reduced in the dry period, especially for submerged macrophytes and floating-leaf macrophytes. Our results may be helpful for the aquatic restoration in the future. PMID:28261516

  13. Historical trends of concentrations, source contributions and toxicities for PAHs in dated sediment cores from five lakes in western China.

    PubMed

    Xu, Jian; Guo, Jian-Yang; Liu, Gui-Rong; Shi, Guo-Liang; Guo, Chang-Sheng; Zhang, Yuan; Feng, Yin-Chang

    2014-02-01

    In this work, sixteen U.S. EPA priority PAH compounds in the dated sediment cores were detected from five lakes in western China. In most lakes, the concentrations of the total PAHs (ΣPAHs) increased from the deep layers to the surface sediments. Two source categories, i.e. vehicular emission and biomass & domestic coal combustion were identified by Unmix, a factor analysis receptor model to explore the source contributions of PAHs in the dated sediments. The source apportionment results showed that biomass & domestic coal combustion contributed larger proportion of PAHs in the five lakes. The toxicities of PAHs in the dated sediments, assessed by BaP equivalent (BaPE) values showed that the BaPE increased gradually from the deep layers to the surface sediments in most lakes. For the first effort, the contribution of each source to BaPE was apportioned by Unmix-BaPE method, and the result indicated that the vehicular emission posed the highest toxic risk. The percentage contribution of vehicular emission for PAHs and BaPE also increased from the deep layers to the surface sediments, while biomass & domestic coal combustion exhibited the opposite tendency.

  14. Variation in aeolian environments recorded by the particle size distribution of lacustrine sediments in Ebinur Lake, northwest China.

    PubMed

    Ma, Long; Wu, Jinglu; Abuduwaili, Jilili

    2016-01-01

    Particle size analysis of lacustrine core sediments and atmospheric natural dust were conducted in the drainage area of Ebinur Lake in arid northwest China. Using a combination of (137)Cs and (210)Pb dating, a continuous record of aeolian transportation to the lake sediments and related factors over about the past 150 years was analyzed. Factor analysis revealed the particle-size distributions of riverine and aeolian sediments composed of the terrigenous materials of the lake deposits. Compared with the grain-size distributions of natural dust samples, the results showed that the coarser particle size fraction of lake sediments was mainly derived from the sediments that had experienced aeolian transport to the drainage surface, and the finer sediments came from hydraulic inputs. Then, the method of variations in particle-size standard deviation was used to extract the grain size intervals with the highest variability along a sedimentary sequence. The coarser grain-size populations dominated the variation patterns of the sedimentary sequence. During the last 150 years, strong intensity aeolian transportation occurred during three periods, 1915-1935, 1965-1975 and since the beginning of the 2000s. The climate was dry around 1910s-1930s in this region associated with the appropriate dynamic condition, which provided the enhanced source materials and wind power for the aeolian dust transport. Since 1950s, the climate controlled the foundation of aeolian dust transport, and the aeolian dust transport won't be increased under the humid climate.

  15. Vertical distribution of Fe and Fe(III)-reducing bacteria in the sediments of Lake Donghu, China.

    PubMed

    Tian, Cuicui; Wang, Chunbo; Tian, Yingying; Wu, Xingqiang; Xiao, Bangding

    2015-08-01

    In lake sediments, iron (Fe) is the most versatile element, and the redox cycling of Fe has a wide influence on the biogeochemical cycling of organic and inorganic substances. The aim of the present study was to analyze the vertical distribution of Fe and Fe(III)-reducing bacteria (FeRB) in the surface sediment (30 cm) of Lake Donghu, China. At the 3 sites we surveyed, FeRB and Fe(II)-oxidizing bacteria (FeOB) coexisted in anoxic sediments. Geobacter-related FeRB accounted for 5%-31% of the total Bacteria, while Gallionella-related FeOB accounted for only 0.1%-1.3%. A significant correlation between the relative abundance of poorly crystalline Fe and Geobacter spp. suggested that poorly crystalline Fe favored microbial Fe(III) reduction. Poorly crystalline Fe and Geobacter spp. were significantly associated with solid-phase Fe(II) and total inorganic phosphorus levels. Pore water Fe(II) concentrations negatively correlated with NO3(-) at all sites. We concluded that Geobacter spp. were abundant in the sediments of Lake Donghu, and the redox of Fe might participate in the cycling of nitrogen and phosphorus in sediments. These observations provided insight into the roles of microbial Fe cycling in lake sediments.

  16. Contamination by metals and pharmaceuticals in northern Taihu Lake (China) and its relation to integrated biomarker response in fish.

    PubMed

    Lu, Guanghua; Yang, Xiaofan; Li, Zhihua; Zhao, Haizhou; Wang, Chao

    2013-01-01

    Taihu Lake is the largest shallow freshwater lake in eastern China and is suffering not only from an increasingly serious threat of eutrophication but also potential ecological risk due to the input of emerging contaminants. Active biomonitoring was conducted in Taihu Lake using transplanted goldfish (Carassius auratus) to determine the contamination by pharmaceuticals and metals and to assess the potential ecological risk. A suite of biomarkers including acetylcholinesterase, ethoxyresorufin O-deethylase, glutathione S-transferase, glutathione peroxidase and superoxide dismutase activities in fish after 7, 14, 21 and 28 days of exposure in situ, as well as pharmaceuticals and metals in water, were determined during the field exposure period. The results indicate that pharmaceuticals exist mainly in Zhushan Bay and Meiliang Bay, while metals are present mainly in Gong Bay. An integrated biomarker response (IBR) was calculated and used to evaluate the ecological risk of the polluted area of Taihu Lake. It was found that Zhushan Bay might present higher risk to fish, followed by Meiliang Bay. IBR values were in good agreement with copper and caffeine concentrations.

  17. 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.

  18. Occurrence, distribution, and risk assessment of antibiotics in the surface water of Poyang Lake, the largest freshwater lake in China.

    PubMed

    Ding, Huijun; Wu, Yixiao; Zhang, Weihao; Zhong, Jiayou; Lou, Qian; Yang, Ping; Fang, Yuanyuan

    2017-10-01

    SPE-UPLC-MS/MS was used to investigate the occurrence of 18 target antibiotics in the surface water of Poyang Lake over different seasons of 2014-2015. The maximum concentrations of sulfadiazine, oxytetracycline, and doxycycline were 56.2, 48.7, and 39.7 ng/L, respectively. Compared with those in the other lakes or surface waters, the surface water of Poyang Lake contained moderate or below-average levels of antibiotics. The significantly lower concentrations (P < 0.01) of roxithromycin in June 2015 likely resulted from the dilution effect of water flow during the flood season. Antibiotic concentrations were higher in site P3-1 than in other sites (P < 0.01), whereas those in other sites (P1-1, P2-1, P5-1, P6-1, P7-1, P13-1, P16-1, P17-1, P18-1) were not significantly different (P > 0.05). Given that tetracyclines and sulfonamides are common veterinary medicines, the high concentrations of oxytetracycline, doxycycline, and sulfadiazine in site P3-1 might be closely related to agricultural production in the surrounding areas. The risk assessment of the main antibiotic contaminants revealed that the majority of the risk quotients of the target antibiotics were below 0.01, thereby indicating the minimal risk of these antibiotics to organisms at three different trophic levels. Sulfadimidine and sulfadiazine were identified as the main antibiotics that contribute to ecological risk in Poyang Lake, and that the daphnid is the main model organism exposed to these risks. This study provides important data for antibiotic pollution control and environmental protection in the study area and enriches environmental monitoring data on a global scale. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Controlling cyanobacterial blooms by managing nutrient ratio and limitation in a large hyper-eutrophic lake: Lake Taihu, China.

    PubMed

    Ma, Jianrong; Qin, Boqiang; Wu, Pan; Zhou, Jian; Niu, Cheng; Deng, Jianming; Niu, Hailin

    2015-01-01

    Excessive nitrogen (N) and phosphorus (P) loading of aquatic ecosystems is a leading cause of eutrophication and harmful algal blooms worldwide, and reducing nutrient levels in water has been a primary management objective. To provide a rational protection strategy and predict future trends of eutrophication in eutrophic lakes, we need to understand the relationships between nutrient ratios and nutrient limitations. We conducted a set of outdoor bioassays at the shore of Lake Taihu. It showed that N only additions induced phytoplankton growth but adding only P did not. Combined N plus P additions promoted higher phytoplankton biomass than N only additions, which suggested that both N and P were deficient for maximum phytoplankton growth in this lake (TN:TP=18.9). When nutrients are present at less than 7.75-13.95 mg/L TN and 0.41-0.74 mg/L TP, the deficiency of either N or P or both limits the growth of phytoplankton. N limitation then takes place when the TN:TP ratio is less than 21.5-24.7 (TDN:TDP was 34.2-44.3), and P limitation occurs above this. Therefore, according to this ratio, controlling N when N limitation exists and controlling P when P deficiency is present will prevent algal blooms effectively in the short term. But for the long term, a persistent dual nutrient (N and P) management strategy is necessary. Copyright © 2014. Published by Elsevier B.V.

  20. A 100-year sedimentary record of natural and anthropogenic impacts on a shallow eutrophic lake, Lake Chaohu, China.

    PubMed

    Zan, Fengyu; Huo, Shouliang; Xi, Beidou; Zhu, Chaowei; Liao, Haiqing; Zhang, Jingtian; Yeager, Kevin M

    2012-03-01

    In this study, the sediment profiles of total organic carbon, total nitrogen, C/N ratios, total phosphorus, N/P ratios, C/P ratios, particle sizes, and stable carbon and nitrogen isotopes (δ(13)C and δ(15)N) were used to investigate natural and anthropogenic impacts on Lake Chaohu over the past 100 years. Before 1960, Lake Chaohu experienced low productivity and a relatively steady and low nutrient input. The increasing concentration and fluxes of total organic carbon, total nitrogen, total phosphorus, together with changes in the δ(13)C and δ(15)N of organic material in the sediment cores, suggested that the anthropogenic effects on trophic status first started because of an increase in nutrient input caused by a population increase in the drainage area. With the construction of the Chaohu Dam, an increase in the utilization of fertilizer and the population growth which occurred since 1960, stable depositional conditions and increasing nutrient input resulted in a dominantly algae-derived organic matter source and high productivity. Nutrient input increased most significantly around 1980 following the rapidly growing population, with concomitant urbanization, industrial and agricultural development. This study also revealed that the concentration and distribution of nutrients varied between different areas of sediment within Lake Chaohu because of the influence of different drainage basins and pollution sources.

  1. From Schistosomiasis Vector Habitats Identification to Human Transmission Risk Mapping, in the Poyang Lake Area (Jiangxi Province, PR China)

    NASA Astrophysics Data System (ADS)

    Marie, T.; Huber, C.; Yesou, H.

    2013-01-01

    Schistosomiasis (Bilharzias) is the most frequent disease after malaria in the world. This disease hit 200 million people, and threats 600 million people. In China, Schistosomiasis japonicum, a serious communicable parasitic disease, is endemic along the Yangtze River basin, including monsoon lakes. Risky transmission areas are conditioned by the S. japonicum vector’s presence and human activities and presence. On Poyang Lake, marshlands are the principal area of its development. The aim of this work is to answer : Where are areas suitable for vector’s disease development ? Where and what are the human activities the most exposed to disease transmission ? Where are urban areas with the higher level of disease transmission risk ? How data crossing can be useful for identification of areas with the higher transmission risk level ?

  2. Distribution characteristic of soil organic carbon fraction in different types of wetland in Hongze Lake of China.

    PubMed

    Lu, Yan; Xu, Hongwen

    2014-01-01

    Soil organic carbon fractions included microbial biomass carbon (MBC), dissolved organic carbon (DOC), and labile organic carbon (LOC), which was investigated over a 0-20 cm depth profile in three types of wetland in Hongze Lake of China. Their ecoenvironmental effect and the relationships with soil organic carbon (SOC) were analyzed in present experiment. The results showed that both active and SOC contents were in order reduced by estuarine wetland, flood plain, and out-of-lake wetland. Pearson correlative analysis indicated that MBC and DOC were positively related to SOC. The lowest ratios of MBC and DOC to SOC in the estuarine wetland suggested that the turnover rate of microbial active carbon pool was fairly low in this kind of wetland. Our results showed that estuarine wetland had a strong carbon sink function, which played important role in reducing greenhouse gas emissions; besides, changes of water condition might affect the accumulation and decomposition of organic carbon in the wetland soils.

  3. 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.

  4. 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.

  5. Effects of sludge dredging on the prevention and control of algae-caused black bloom in Taihu Lake, China.

    PubMed

    He, Wei; Shang, Jingge; Lu, Xin; Fan, Chengxin

    2013-03-01

    Algae-caused black bloom (also known as black water agglomerate) has recently become a critical problem in some Chinese lakes. It has been suggested that the occurrence of algae-caused black bloom was caused by the cooperation of nutrient-rich sediment with dead algae, and sludge dredging was adopted to control black bloom in some lakes of China. In this article, based on the simulation of black bloom using a Y-shape apparatus for modeling natural conditions, both un-dredged and dredged sites in three areas of Taihu-Lake, China were studied to estimate the effects of dredging on the prevention and control of black bloom. During the experiment, drained algae were added to all six sites as an additional organic load; subsequently, the dissolved oxygen decreased rapidly, dropping to 0 mg/L at the sediment-water interface. Black bloom did not occur in the dredged sites of Moon Bay and Nan Quan, whereas all three un-dredged sites at Fudu Port, Moon Bay and Nan Quan experienced black bloom. Black bloom also occurred at the dredged site of Fudu Port one day later than at the other sites, and the odor and color were lighter than at the other locations. The color and odor of the black water mainly result from the presence of sulfides such as metal sulfides and hydrogen sulfide, among other chemicals, under reductive conditions. The color and odor of the water, together with the high concentrations of nutrients, were mainly caused by the decomposition of the algae and the presence of nutrient-rich sediment. Overall, the removal of the nutrient-rich sediment by dredging can prevent the occurrence and control the degree of algae-caused black bloom in Taihu Lake.

  6. 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

  7. 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.

  8. Occurrence and human dietary assessment of fluoroquinolones antibiotics in cultured fish around Tai Lake, China.

    PubMed

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

    2017-06-06

    Fluoroquinolone antibiotics are widely used in the production of aquatic products and considered to be a significant contributing factor to the burden of both natural and aquaculture environments. However, the main types of fluoroquinolones present in aquaculture systems have not been determined. The objectives of the present study were to explore the occurrence of residual fluoroquinolone antibiotics in fish muscle tissues sampled from across the entire aquaculture season in the Tai Lake basin in China and to assess the dietary risks associated with the upcoming vendible fish in the last month of the aquaculture season. Fluoroquinolones were detected in 95.69% of all fish samples, and the concentrations ranged from the limit of quantification (LOQ) to 47 108.00 μg · kg(-1) . Enrofloxacin contributed the most among the 9 fluoroquinolone antibiotics tested. Of the 4 fish species studied, enrofloxacin was present in bream at significant (p < 0.05) concentrations in August, with an average value of 321.45 μg · kg(-1) , while enrofloxacin concentrations peaked in crab and shrimp in September, with average values of 6949.60 and 460.82 μg · kg(-1) , respectively. However, different patterns were observed in perch, suggesting that other categories of antibiotics may be used in the production of this fish. Dietary risk assessment showed that the residual levels and estimated daily intake in bream, perch, and shrimp were far below the maximum residual level and acceptable daily intake. However, the average residual level in crab exceeded the maximum residual level, and the estimated daily intake value accounted for 78.49% of the acceptable daily intake, indicating potential consumption risk. In summary, the present study aims to guide the production and consumption of aquatic products. Environ Toxicol Chem 2017;9999:1-7. © 2017 SETAC. © 2017 SETAC.

  9. Modeling Nutrient Release in the Tai Lake Basin of China: Source Identification and Policy Implications

    NASA Astrophysics Data System (ADS)

    Liu, Beibei; Liu, Heng; Zhang, Bing; Bi, Jun

    2013-03-01

    Because nutrient enrichment has become increasingly severe in the Tai Lake Basin of China, identifying sources and loads is crucial for watershed nutrient management. This paper develops an empirical framework to estimate nutrient release from five major sectors, which requires fewer input parameters and produces acceptable accuracy. Sectors included are industrial manufacturing, livestock breeding (industrial and family scale), crop agriculture, household consumption (urban and rural), and atmospheric deposition. Results show that in the basin (only the five sectors above), total nutrient loads of nitrogen (N) and phosphorus (P) into aquatic systems in 2008 were 33043.2 tons N a-1 and 5254.4 tons P a-1, and annual area-specific nutrient loads were 1.94 tons N km-2 and 0.31 tons P km-2. Household consumption was the major sector having the greatest impact (46 % in N load, 47 % in P load), whereas atmospheric deposition (18 %) and crop agriculture (15 %) sectors represented other significant proportions of N load. The load estimates also indicate that 32 % of total P came from the livestock breeding sector, making it the second largest phosphorus contributor. According to the nutrient pollution sectors, six best management practices are selected for cost-effectiveness analysis, and feasible options are recommended. Overall, biogas digester construction on industrial-scale farms is proven the most cost-effective, whereas the building of rural decentralized facilities is the best alternative under extreme financial constraint. However, the reduction potential, average monetary cost, and other factors such as risk tolerance of policy makers should all be considered in the actual decision-making process.

  10. 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.

  11. Emergy evaluation and economic analysis of three wetland fish farming systems in Nansi Lake area, China.

    PubMed

    Zhang, L X; Ulgiati, S; Yang, Z F; Chen, B

    2011-03-01

    Emergy and economic methods were used to evaluate and compare three fish production models, i.e., cage fish farming system, pond intensive fish rearing system and semi-natural extensive pond fish rearing system, in Nansi Lake area in China in the year 2007. The goal of this study was to understand the benefits and driving forces of selected fish production models from ecological and economic points of view. The study considered input structure, production efficiency, environmental impacts, economic viability and sustainability. Results show that the main difference among the three production systems was the emergy cost for fish feed associated with their feeding system, i.e., feeding on natural biomass such as plankton and grass or on commercial feedstock. As indicated by EYR, ELR and ESI, it can be clearly shown that the intensive production model with commercial feed is not a sustainable pattern. However, the point is that more environmentally sound patterns do not seem able to provide a competitive net profit in the short run. The intensive pond fish farming system had a net profit of 2.57E+03 $/ha, much higher than 1.27E+03 $/ha for cage fish farming system and slightly higher than 2.37E+03 $/ha for semi-natural fish farming system. With regard to the drivers of local farmer's decisions, the accessibility of land for the required use and investment ability determine the farmer's choice of the production model and the scale of operation, while other factors seem to have little effect. Theoretically, the development of environmentally sustainable production patterns, namely water and land conservation measures, greener feed as well as low waste systems is urgently needed, to keep production activities within the carrying capacity of ecosystems. Coupled emergy and economic analyses can provide better insight into the environmental and economic benefits of fish production systems and help solve the problems encountered during policy making.

  12. Rhizobium albus sp. nov., Isolated from Lake Water in Xiamen, Fujian Province of China.

    PubMed

    Li, Yi; Lei, Xueqian; Xu, Yanting; Zhu, Hong; Xu, Meiying; Fu, Lijun; Zheng, Wei; Zhang, Jinli; Zheng, Tianling

    2017-01-01

    A Gram-stain-negative, aerobic bacterial strain, designated Y21(T), was isolated from surface lake water in Xiamen, Fujian Province of China. Growth was observed at temperatures from 4 to 37 °C, at salinities from 0 to 7.0 % and at pH from 6.0 to 10.0. Optimum growth was observed at 28 °C, at pH 7.0 and with 1.5-2.0 % (w/v) NaCl. The highest similarity of 16S rRNA gene sequence between strain Y21(T) and the other strains was 96.9 %. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that the strain was a member of the genus Rhizobium, forming a distinct lineage with R. subbaraonis KCTC 23614(T). The dominant fatty acids were summed feature 8 (comprising C18:1 ω7c and/or C18:1 ω6c), C18:1 ω7c 11-methyl, which accounted for 78.1 %. The G+C content of the chromosomal DNA was 60.9 mol%. The predominant respiratory quinone was ubiquinone-10. The polar lipids of strain Y21(T) were found to consist of five unidentified phospholipids and three unidentified aminolipids. According to its morphology, physiology, fatty acid composition and 16S rRNA sequence data, strain Y21(T) should be regarded as a new species of the genus Rhizobium, for which Rhizobium albus sp. nov. is proposed (type strain Y21(T) = MCCC 1F01210(T) = KCTC 42252(T)).

  13. 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

  14. Halobellus rarus sp. nov., a halophilic archaeon from an inland salt lake of China.

    PubMed

    Zhang, Wen-Jiao; Han, Dong; Qiu, Xing-Xing; Zhao, Mei-Lin; Mou, Yun-Zhuang; Cui, Heng-Lin; Li, Zheng-Rong

    2013-09-01

    Two halophilic archaeal strains, YC21(T) and YC77, were isolated from an inland salt lake of China. Both have pleomorphic rod-shaped cells that lyse in distilled water, stain Gram-negative and form red-pigmented colonies. They are neutrophilic, require at least 2.1 M NaCl for growth under the optimum growth temperature of 37 °C. The major polar lipids of the two strains were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfate (PGS), two major glycolipids (GL1 and GL2) chromatographically identical to sulfated mannosyl glucosyl diether (S-DGD-1) and mannosyl glucosyl diether (DGD-1), respectively. Trace amounts of two unidentified lipids (GL0-1 and GL0-2) were also detected. The 16S rRNA gene sequences of the two strains are 99.9 % identical, show 94.0-98.9 % similarity to the closest relative members of Halobellus of the family Halobacteriaceae. The rpoB' gene similarity between strains YC21(T) and YC77 is 99.8 % and show 90.3-95.3 % similarity to the closest relative members of Halobellus. The DNA G+C content of strains YC21(T) and YC77 were 66.1 and 66.2 mol%, respectively. The DNA-DNA hybridization value between strain YC20(T) and strain YC77 was 89 %, and the two strains showed low DNA-DNA relatedness with Halobellus limi TBN53(T), the most related member of Halobellus. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strains YC21(T) and YC77 represent a novel species of the genus Halobellus, for which the name Halobellus rarus sp. nov. is proposed. The type strain is YC21(T) (=CGMCC 1.12121(T) = JCM 18362(T)).

  15. 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.

  16. 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

  17. Modeling nutrient release in the Tai Lake basin of China: source identification and policy implications.

    PubMed

    Liu, Beibei; Liu, Heng; Zhang, Bing; Bi, Jun

    2013-03-01

    Because nutrient enrichment has become increasingly severe in the Tai Lake Basin of China, identifying sources and loads is crucial for watershed nutrient management. This paper develops an empirical framework to estimate nutrient release from five major sectors, which requires fewer input parameters and produces acceptable accuracy. Sectors included are industrial manufacturing, livestock breeding (industrial and family scale), crop agriculture, household consumption (urban and rural), and atmospheric deposition. Results show that in the basin (only the five sectors above), total nutrient loads of nitrogen (N) and phosphorus (P) into aquatic systems in 2008 were 33043.2 tons N a(-1) and 5254.4 tons P a(-1), and annual area-specific nutrient loads were 1.94 tons N km(-2) and 0.31 tons P km(-2). Household consumption was the major sector having the greatest impact (46 % in N load, 47 % in P load), whereas atmospheric deposition (18 %) and crop agriculture (15 %) sectors represented other significant proportions of N load. The load estimates also indicate that 32 % of total P came from the livestock breeding sector, making it the second largest phosphorus contributor. According to the nutrient pollution sectors, six best management practices are selected for cost-effectiveness analysis, and feasible options are recommended. Overall, biogas digester construction on industrial-scale farms is proven the most cost-effective, whereas the building of rural decentralized facilities is the best alternative under extreme financial constraint. However, the reduction potential, average monetary cost, and other factors such as risk tolerance of policy makers should all be considered in the actual decision-making process.

  18. Characteristics of petroleum contaminants and their distribution in Lake Taihu, China

    PubMed Central

    2012-01-01

    Background Taihu Lake is a typical plain eutrophic shallow lake. With rapidly economic development of the lake area, the petroleum products and oil wastewater produced in various processes have been inevitably discharged into Taihu Lake. As the major fresh water resource in the economically developed region of Yangtze River Delta, the water quality and environmental condition of Taihu Lake have the direct bearing on the natural environment and sustainable development of economy in this region. For this reason we carried out the study to explore the composition, distribution characteristics and sources of petroleum contaminants in Taihu Lake. The aim of this study was to provide the basis for standard management and pollution control of the Taihu Lake environment. Results The result showed that water samples from near industrial locations were of relatively higher petroleum contaminants concentrations. The oil pollutants concentrations in different areas of Lake Taihu ranged from 0.106 mg/L to 1.168 mg/L, and the sequence of total contents distribution characteristics of petroleum pollutants from high to low in different regions of Taihu Lake was: “Dapu”, “Xiaomeikou”, “Zhushan Bay”, “Lake center”, “Qidu”. The results showed that total concentrations of n-alkanes and PAHs ranged from 0.045 to 0.281 mg/L and from 0.011 to 0.034 mg/L respectively. In the same region, the concentrations of hydrocarbon pollutants in the surface and bottom of the lake were higher than that in the middle. Conclusion This paper reached a conclusion that the petroleum contaminants in Taihu Lake mainly derived from petroleum pollution caused by human activities as indicated by OEP, bimodal distribution, CPI, Pr/Ph ratio, the LMW/HMW ratio and other evaluation indices for sources of n-alkanes and polycyclic aromatic hydrocarbons (PAHs). PMID:22935425

  19. Pyrosequencing analysis of free-living and attached bacterial communities in Meiliang Bay, Lake Taihu, a large eutrophic shallow lake in China.

    PubMed

    Tang, Xiangming; Li, Linlin; Shao, Keqiang; Wang, Boweng; Cai, Xianlei; Zhang, Lei; Chao, Jianying; Gao, Guang

    2015-01-01

    To elucidate the relationship between particle-attached (PA, ≥ 5.0 μm) and free-living (FL, 0.2-5.0 μm) bacterial communities, samplings were collected seasonally from November 2011 to August 2012 in Meiliang Bay, Lake Taihu, China. We used 454 pyrosequencing of 16S rRNA genes to study bacterial diversity and structure of PA and FL communities. The analysis rendered 37,985 highly qualified reads, subsequently assigned to 1755 operational taxonomic units (97% similarity) for the 8 samples. Although 27 high-level taxonomic groups were obtained, the 3 dominant phyla (Proteobacteria, Actinobacteria, and Bacteroidetes) comprised about 75.9% and 82.4% of the PA and FL fractions, respectively. Overall, we found no significant differences between community types, as indicated by ANOSIM R statistics (R = 0.063, P > 0.05) and the Parsimony test (P = 0.222). Dynamics of bacterial communities were correlated with changes in concentrations of total suspended solids (TSS) and total phosphorus (TP). In summer, a significant taxonomic overlap in the 2 size fractions was observed when Cyanobacteria, a major contributor of TSS and TP, dominated in the water, highlighting the potential rapid exchange between PA and FL bacterial populations in large shallow eutrophic lakes.

  20. Bathymetric and sediment facies maps for China Bend and Marcus Flats, Franklin D. Roosevelt Lake, Washington, 2008 and 2009

    USGS Publications Warehouse

    Weakland, Rhonda J.; Fosness, Ryan L.; Williams, Marshall L.; Barton, Gary J.

    2011-01-01

    The U.S. Geological Survey (USGS) created bathymetric and sediment facies maps for portions of two reaches of Lake Roosevelt in support of an interdisciplinary study of white sturgeon (Acipenser transmontanus) and their habitat areas within Franklin D. Roosevelt Lake, Washington. In October 2008, scientists from the USGS used a boat-mounted multibeam echo sounder (MBES) to describe bathymetric data to characterize surface relief at China Bend and Marcus Flats, between Northport and Kettle Falls, Washington. In March 2009, an underwater video camera was used to view and record sediment facies that were then characterized by sediment type, grain size, and areas of sand deposition. Smelter slag has been identified as having the characteristics of sand-sized black particles; the two non-invasive surveys attempted to identify areas containing black-colored particulate matter that may be elements and minerals, organic material, or slag. The white sturgeon population in Lake Roosevelt is threatened by the failure of natural recruitment, resulting in a native population that consists primarily of aging fish and that is gradually declining as fish die and are not replaced by nonhatchery reared juvenile fish. These fish spawn and rear in the riverine and upper reservoir reaches where smelter slag is present in the sediment of the river lake bed. Effects of slag on the white sturgeon population in Lake Roosevelt are largely unknown. Two recent studies demonstrated that copper and other metals are mobilized from slag in aqueous environments with concentrations of copper and zinc in bed sediments reaching levels of 10,000 and 30,000 mg/kg due to the presence of smelter slag. Copper was found to be highly toxic to 30-day-old white sturgeon with 96-h LC50 concentrations ranging from 3 to 5 (u or mu)g copper per liter. Older juvenile and adult sturgeons commonly ingest substantial amounts of sediment while foraging. Future study efforts in Lake Roosevelt should include sampling of

  1. Precipitation and temperature drive seasonal variation in bioaccumulation of polycyclic aromatic hydrocarbons in the planktonic food webs of a subtropical shallow eutrophic lake in China.

    PubMed

    Tao, Yuqiang; Yu, Jing; Xue, Bin; Yao, Shuchun; Wang, Sumin

    2017-04-01

    Hydrophobic organic contaminants (HOCs) are toxic and ubiquitous in aquatic environments and pose great risks to aquatic organisms. Bioaccumulation by plankton is the first step for HOCs to enter aquatic food webs. Trophic status is considered to dominate variations in bioaccumulation of HOCs in plankton in temperate and frigid deep oligotrophic waters. However, long-term driving factors for bioaccumulation of HOCs in planktonic food webs of subtropical shallow eutrophic waters have not been well investigated. China has the largest subtropical lake density in the Northern Hemisphere. Due to limited field data, long-term variations in the bioaccumulation of HOCs in these lakes are almost unknown. Here we take Lake Xuanwu as an example to investigate long-term variations in the bioaccumulation, and biomagnification of polycyclic aromatic hydrocarbon (PAHs) in planktonic food webs of subtropical shallow eutrophic lakes in China, and elucidate the driving factors. Our results indicate that temperature rather than nutrients dominates long-term dynamics of planktonic biomass in this lake. Precipitation significantly enhances the concentrations of the PAHs, and total suspended particles, and consequently affects the distribution of the PAHs in the water column. Biomass dilution induced by temperature dominates bioaccumulation of the PAHs by both phytoplankton and zooplankton (copepods and cladocerans). Biomagnification of the PAHs from phytoplankton to zooplankton is positively correlated with temperature. Our study suggests that temperature and precipitation drive long-term variations in the bioaccumulation of the PAHs in the planktonic food webs of this subtropical shallow eutrophic lake. Lake Xuanwu has a similar mean annual temperature, annual precipitation, sunshine duration, and nutrient levels as other subtropical shallow eutrophic lakes in China. This study may also help to understand the bioaccumulation of HOCs in planktonic food webs of other subtropical shallow

  2. Spatial distribution and abundance of small fishes in Xiaosihai Lake, a shallow lake along the Changjiang (Yangtze) River, China

    NASA Astrophysics Data System (ADS)

    Li, Wei; Zhang, Tanglin; Li, Zhongjie

    2010-05-01

    Spatial distribution and abundance of small fishes were studied in autumn 2007 in the Xiaosihai Lake, a shallow lake along the middle reach of the Changjiang (Yangtze) River. Based on the plant cover, the lake was divided into three major habitats: Myriophyllum spicatum habitat (MS habitat), Trapa bispinosa habitat (TB habitat), and non-vegetation habitat (NV habitat). A modified pop-net was used for quantitative sampling of small fishes in the three habitats, and the Zippin’s removal method was used for estimating densities of the small fishes. A total of 13 species belonging to 5 families were collected, with 11 species in MS habitat, 7 species in TB habitat, and 5 species in NV habitat. Habitat type had significant effect on the spatial distribution of small fishes. The Shannon-Wiener diversity index in the MS, TB and NV habitats were 1.28, 0.56 and 0.54, respectively. The total density and biomass of small fishes were significantly higher in the MS habitat (13.68 ind/m2 and 4.44 g/m2) than in the TB habitat (1.41 ind/m2 and 0.54 g/m2) and the NV habitat (1.08 ind/m2 and 0.40 g/m2), and were not significantly different between the TB habitat and the NV habitat. Water depth had no significant effect on spatial distribution of the small fishes. It was suggested that vegetation type played an important role in habitat selectivity of small fishes, and the presence of submersed vegetation should be of significance in the conservation of small fish diversity.

  3. Polybrominated diphenyl ethers occurrence in major inflowing rivers of Lake Chaohu (China): characteristics, potential sources and inputs to lake.

    PubMed

    Wang, Xiaowei; Xi, Beidou; Huo, Shouliang; Deng, Lin; Pan, Hongwei; Xia, Xunfeng; Zhang, Jingtian; Ren, Yuqing; Liu, Hongliang

    2013-11-01

    Eight commonly occurring polybrominated diphenyl ethers (PBDEs), including BDE 28, 47, 99, 100, 153, 154, 183, 207, and 209, were investigated in water samples from seven major inflowing rivers of Lake Chaohu to determine the distribution characteristics, potential sources and inputs to the lake. The sum of 8 BDE congeners (Σ8PBDEs) had a concentration varied from 0.31 to 84 ng L(-1), with those of BDE 209, BDE 47, BDE 99, and BDE 153 being 0.31-83, <0.012-0.36, <0.012-1.3, and <0.012-0.77 ng L(-1), respectively. These levels were in the high range of the global PBDEs concentrations in the water environments. The highest concentrations of Σ8PBDEs were detected in the western rivers, of which the main pollution sources were strongly related to human activities in urban centers, such as automobile-derived wastes. A sewage treatment plant was likely an important source of the lower brominated BDEs input to one western river. The correlation analyses (all p<0.05) between PBDEs and DOC, TN, TP, and EC, suggested that the distributions and sources of PBDEs in rivers might also be related with the soil erosion by heave floods. Σ8PBDEs input to Lake Chaohu from the rivers outlets was estimated at 344 kg yr(-1) during the flood season. BDE 209 was the dominant contributor with an input of 340 kg yr(-1), followed by BDE 99 (1.3 kg yr(-1)), BDE 47 (0.83 kg yr(-1)) and BDE 153 (0.60 kg yr(-1)). Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. 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

  5. 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

  6. a Study on the Comprehensive Simulation of Nonpoint Source Pollution for Er-Hai Lake's Watershed in Dali of China

    NASA Astrophysics Data System (ADS)

    Yang, K.; Xu, Q. L.; Ye, L. Y.

    2012-07-01

    Er-hai Lake lies in state of Dali of Yunnan Province in China, which is so important to the local people that they revere her as the Mother Lake. Unfortunately, she is threatened by the more serious pollution of water. And from the water quality assessment of Er-hai Lake over the years, it is indicated that the major water pollution source come from nonpoint source pollution. The argument is that what has formed the nonpoint source pollution? As we known, the land use and cover change of watershed called LUCC is deemed as the major reason for Non-point pollution of water. However, what has made the land use and cover changes? It is another important question we should give an answer for water pollution. Many evidences have given that the change of LUCC is more due to the human activities in watershed, especially those for agriculture production. Thereby, there is a chain process for water pollution formation in Er-hai Lake Watershed, which could be described like this: Human activities (more in agriculture) have changed LUCC, and LUCC leads non-point source pollution. As a result, in this paper, those have been discussed according to the driving mechanism of nonpoint source water pollution in Er-hai Lake, which include three explorations. The first is how to build a ABM-LUCC model by using Repast and GIS technology, and the second is the method and implementation for hydrological and water quality model by using SWAT model and GIS, as well as Remote Sensing technology. And establishing a platform for comprehensively simulating the whole process of water pollution by integrating GIS, ABM-LUCC models and hydrological models is the last work for this study.

  7. 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

  8. [Pollution characteristics and evaluation of nitrogen, phosphorus and organic matter in surface sediments of Lake Changshouhu in Chongqing, China].

    PubMed

    Lu, Shao-Yong; Xu, Meng-Shuang; Jin, Xiang-Can; Huang, Guo-Zhong; Hu, Wen

    2012-02-01

    In order to reveal spatial distribution characteristics of nutrient in the surface sediments of Lake Changshouhu, contents of total nitrogen (TN), total phosphorus (TP) and organic matter (OM) of 62 surface sediments samples were determined and compared with other urban (suburban) lakes in China. C/N and the correlation of TN, TP and OM had also been analyzed. The results showed that the average contents of TN and TP were 2 255.89 mg x kg(-1) and 622.03 mg x kg(-1) respectively. Nitrogen and phosphorus pollution were very serious all over the lake, with a significantly different spatial distribution. The average content of OM was 2.80%. So the contents of TN, TP and OM were in the middle level compared with other lakes. 87.10% of C/N was between 5 and 14 (72.58% within which was between 6 and 13) and 3.23% of C/N was between 2.8 and 3.4, which showed that OM came from algae, phytoplankton and zooplankton. Besides, a small part of OM came from aquatic organisms. OM and TN were significantly correlated (Pearson coefficient was 0.849), but with less significant correlation to TP. The spatial distribution characteristics of OM were very similar with that of TN. The content of OM in water samples collected from western and middle waterbody was higher than that in eastern waterbody, which was the same as TN. By evaluating pollution situation with organic index and organic nitrogen, the average organic index was 0.386 which was on the III level still belonged to clean category. However, the average number of organic nitrogen was up to 0.214% which was on the IV level indicated the pollution degree. This showed that the lake Changshouhu was in a serious pollution situation especially in nitrogen pollution.

  9. 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.

  10. Estimates of long-term water total phosphorus (TP) concentrations in three large shallow lakes in the Yangtze River basin, China.

    PubMed

    Wu, Pan; Qin, Boqiang; Yu, Ge

    2016-03-01

    The shallow lakes in the eastern China developed on alluvial plains with high-nutrient sediments, and most overflow into the Yangtze River with short hydraulic residence times, whereas they become eutrophic over long time periods. Assuming strong responses to hydrogeological changes in the basin, we attempted to determine the dynamic eutrophication history of these lakes. Although evaluation models for internal total phosphorus (TP) loading are widely used for deep lakes in Europe and North America, the accuracy of these models for shallow lakes that have smaller water volumes controlled by the geometrical morphology and greater basin area of alluvial plains is unknown. To describe the magnitude of changes in velocity of trophic state for the studied shallow lakes, we first evaluated the P retention model in relation to the major forces driving lake morphology, basin climate, and external discharge and then used the model to estimate changes in TP in three large shallow lakes (Taihu, Chao, and Poyang) over 60 years (1950-2009 AD). The observed levels of TP were verified against the relative error of the three lakes (<6.43 %) and Nash-Sutcliffe coefficients (0.67-0.75). The results showed that the predicted TP concentrations largely increased with hydraulic residence time, especially in extreme drought years, with a generally rising trend in trophic status. The simulated trophic state index showed that lakes Taihu and Poyang became eutrophic in the 1990s, whereas Lake Chao became eutrophic in the 1980s; lakes Taihu and Chao ultimately became hypereutrophic in the 2000s. The analysis suggested that the tropic status of the shallow lakes was affected by both the hydroclimate and geological sedimentation of the Yangtze River basin. This work will contribute to the development of an internal P loading model for further evaluating trophic states.

  11. 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

  12. Composition and Biomass of Aquatic Vegetation in the Poyang Lake, China

    PubMed Central

    Du, Wei; Li, Ziqi; Jin, Qiu; Chen, Xi; Jiang, Shanshan

    2017-01-01

    The distribution of aquatic vegetation and associated community diversity and biomass in the Poyang Lake were investigated. The results showed that (1) 43 species of aquatic vascular plants were found in the Poyang Lake watershed which belonged to 22 families; (2) the vegetation of the Poyang Lake scattered in different areas which could be divided into 31 major plant communities and 5 plant zones including amphibian, emergent, floating-leaved, submerged, and floating input; (3) there were 67 aquatic plants in the lake area, and the standing stock (fresh weight) was 1519.41 t. The number of amphibians was the dominant plant species in the Poyang Lake, and the quantity and percentage of amphibians were predominant, which was far more than the other three life forms. PMID:28280648

  13. Composition and Biomass of Aquatic Vegetation in the Poyang Lake, China.

    PubMed

    Du, Wei; Li, Ziqi; Zhang, Zengxin; Jin, Qiu; Chen, Xi; Jiang, Shanshan

    2017-01-01

    The distribution of aquatic vegetation and associated community diversity and biomass in the Poyang Lake were investigated. The results showed that (1) 43 species of aquatic vascular plants were found in the Poyang Lake watershed which belonged to 22 families; (2) the vegetation of the Poyang Lake scattered in different areas which could be divided into 31 major plant communities and 5 plant zones including amphibian, emergent, floating-leaved, submerged, and floating input; (3) there were 67 aquatic plants in the lake area, and the standing stock (fresh weight) was 1519.41 t. The number of amphibians was the dominant plant species in the Poyang Lake, and the quantity and percentage of amphibians were predominant, which was far more than the other three life forms.

  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. Taxonomic and functional diversity provides insight into microbial pathways and stress responses in the saline Qinghai Lake, China.

    PubMed

    Huang, Qiuyuan; Briggs, Brandon R; Dong, Hailiang; Jiang, Hongchen; Wu, Geng; Edwardson, Christian; De Vlaminck, Iwijn; Quake, Stephen

    2014-01-01

    Microbe-mediated biogeochemical cycles contribute to the global climate system and have sensitive responses and feedbacks to environmental stress caused by climate change. Yet, little is known about the effects of microbial biodiversity (i.e., taxonmic and functional diversity) on biogeochemical cycles in ecosytems that are highly sensitive to climate change. One such sensitive ecosystem is Qinghai Lake, a high-elevation (3196 m) saline (1.4%) lake located on the Tibetan Plateau, China. This study provides baseline information on the microbial taxonomic and functional diversity as well as the associated stress response genes. Illumina metagenomic and metatranscriptomic datasets were generated from lake water samples collected at two sites (B and E). Autotrophic Cyanobacteria dominated the DNA samples, while heterotrophic Proteobacteria dominated the RNA samples at both sites. Photoheterotrophic Loktanella was also present at both sites. Photosystem II was the most active pathway at site B; while, oxidative phosphorylation was most active at site E. Organisms that expressed photosystem II or oxidative phosphorylation also expressed genes involved in photoprotection and oxidative stress, respectively. Assimilatory pathways associated with the nitrogen cycle were dominant at both sites. Results also indicate a positive relationship between functional diversity and the number of stress response genes. This study provides insight into the stress resilience of microbial metabolic pathways supported by greater taxonomic diversity, which may affect the microbial community response to climate change.

  16. 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

  17. Decomposition and phosphorus release from four different size fractions of Microcystis spp. taken from Lake Taihu, China.

    PubMed

    Wang, Yuanyuan; Chen, Feizhou

    2008-01-01

    Decomposition of Microcystis is accompanied by the release of phosphorus, during bacteria play an important role. A series of experiments were undertaken to evaluate the effect of bacteria on the decomposition of Microcystis taken from Lake Taihu, China, a lake that is suffering from dense Microcystis blooms. The 16 experiments involved four size fractions of colonial Microcystis with or without the addition of lake sediment and Gram-negative bacterial inhibitor NaN3. The highest decomposition rates were recorded for the smallest size Microcystis fraction (< 25 microm) with the addition of the sediment. The lowest decomposition rates were recorded for the smallest Microcystis fraction without the sediment, but with the addition of Gram-negative bacterial inhibitor NaN3. The higher decomposition rates in the treatments with NaN3 and sediment suggest that Gram-positive bacteria in the sediment are important for the decomposition process. Additionally, higher concentrations of total dissolved phosphorus (TDP) in the treatments with NaN3 suggest that more phosphorus accumulates in the Gram-negative bacterial cells around the colony, which may be an important source of phosphorus for Microcystis cells. In the no-sediment treatments, the ratios of TDP concentration to initial TP concentration were 64%-82%. The results of this experiment suggest that both Gram-negative and Gram-positive bacteria play an important role in the decomposition of Microcystis cells and the release of phosphorus from Microcystis colonies.

  18. Taxonomic and Functional Diversity Provides Insight into Microbial Pathways and Stress Responses in the Saline Qinghai Lake, China

    PubMed Central

    Dong, Hailiang; Jiang, Hongchen; Wu, Geng; Edwardson, Christian; De Vlaminck, Iwijn; Quake, Stephen

    2014-01-01

    Microbe-mediated biogeochemical cycles contribute to the global climate system and have sensitive responses and feedbacks to environmental stress caused by climate change. Yet, little is known about the effects of microbial biodiversity (i.e., taxonmic and functional diversity) on biogeochemical cycles in ecosytems that are highly sensitive to climate change. One such sensitive ecosystem is Qinghai Lake, a high-elevation (3196 m) saline (1.4%) lake located on the Tibetan Plateau, China. This study provides baseline information on the microbial taxonomic and functional diversity as well as the associated stress response genes. Illumina metagenomic and metatranscriptomic datasets were generated from lake water samples collected at two sites (B and E). Autotrophic Cyanobacteria dominated the DNA samples, while heterotrophic Proteobacteria dominated the RNA samples at both sites. Photoheterotrophic Loktanella was also present at both sites. Photosystem II was the most active pathway at site B; while, oxidative phosphorylation was most active at site E. Organisms that expressed photosystem II or oxidative phosphorylation also expressed genes involved in photoprotection and oxidative stress, respectively. Assimilatory pathways associated with the nitrogen cycle were dominant at both sites. Results also indicate a positive relationship between functional diversity and the number of stress response genes. This study provides insight into the stress resilience of microbial metabolic pathways supported by greater taxonomic diversity, which may affect the microbial community response to climate change. PMID:25365331

  19. Influence of nitrogen loading and flooding on seedling emergence and recruitment from a seed bank in Chaohu Lake Basin, China.

    PubMed

    Cui, Naxin; Wu, Juan; Dai, Yanran; Li, Zhu; Cheng, Shuiping

    2017-08-16

    Vegetation severely degraded and even disappeared in the water bodies of Chaohu Lake basin, which is the fifth largest freshwater lake in the Yangtze flood plain in China, because of water pollution and eutrophication. Vegetation restoration projects have been carried out. However, the influences of water quality and hydrology on vegetation restoration from seed banks have been rarely investigated. This experiment aimed to identify the effect of water level and nitrogen loading (ammonium and nitrate) on seedling emergence and recruitment from the riparian seed bank of the river in this basin. Most of the species in the seed bank germinated under moist conditions. Under flooding conditions, however, the growth of aquatic species, especially Vallisneria natans (Lour.) Hara, was inhibited when the nitrogen concentration increased. At 0.37 mg/L NH4(+)-N in the water column, the growth of V. natans was inhibited. The results suggested that flooding was a primary limiting factor of seedling emergence. The inhibitory effect of high nitrogen loading on the growth of aquatic species was one of the main driving mechanisms of macrophyte degradation under flooding conditions; nevertheless, competitive advantage might determine the community pattern in moist habitats. Therefore, water level control and water quality improvement should be the key aspects of vegetation restoration in degraded rivers or lakes.

  20. 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.

  1. Lowly pathogenic avian influenza (H9N2) infection in Plateau pika (Ochotona curzoniae), Qinghai Lake, China.

    PubMed

    Yu, Zhijun; Cheng, Kaihui; Sun, Weiyang; Xin, Yue; Cai, Jinshan; Ma, Ruilin; Zhao, Quanbang; Li, Lin; Huang, Jing; Sang, Xiaoyu; Li, Xue; Zhang, Kun; Wang, Tiecheng; Qin, Chuan; Qian, Jun; Gao, Yuwei; Xia, Xianzhu

    2014-09-17

    Avian influenza viruses (AIVs) are globally important contagions. Several domestic mammals can be infected with AIVs and may play important roles in the adaptation and transmission of these viruses in mammals, although the roles of wild mammals in the natural ecology of AIVs are not yet clear. Here, we performed a serological survey of apparently healthy Plateau pikas at Qinghai Lake in China to assess the prevalence of exposure to AIVs. Ninety-two of 293 (31%) of wild Plateau pikas possessed serum antibodies against a lowly pathogenic avian influenza (LPAI) H9N2 virus. Experimental inoculation of Plateau pikas with a LPAI H9N2 virus resulted in productive viral replication in respiratory tissues without prior adaptation. Our findings suggest that Plateau pikas represent a natural mammalian host to H9N2 AIVs and may play a role in the ongoing circulation of H9N2 viruses at Qinghai Lake in China. Surveillance for AIV infection in Plateau pika populations and other mammals that have close contact with the Plateau pikas should be considered. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. 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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. New evidence for an impact origin of Taihu lake, China: Possible trigger of the extinction of LiangChu Culture 4500 years ago

    NASA Astrophysics Data System (ADS)

    Xie, Z.; Wang, H.; Sharp, T.; Decarli, P.

    2008-12-01

    Here we report new evidence of an impact crater in south-east of China, Taihu Lake in Jiangsu Province. An impact origin was originally proposed on the basis of fractured quartz, wavy extinction quartz, and shatter cones in the sandstone of Devonian Wutong formation in the islands of Taihu lake (Wang, et al., 1992, 1993, 2000). In the absence of additional evidence, the impact origin hypothesis has fallen into disfavour. Here we report studies of sedimentary samples, which could be ejecta from Taihu, found in a small lake in the vicinity of Taihu lake. The samples consist of irregularly-shaped quartz-rich concretions found in lake sediments. Preliminary studies indicate that these samples contain angular fragments of shocked quartz. The stratigraphic age of the lake sediments is similar to that of the 65 km diameter Taihu lake. If the impact origin of Taihu lake can be conclusively established, it is of the correct age to explain the mysterious disappearance of the LiangChu culture about 4500 years ago.

  4. Lake Tangra Yumco as an archive for paleo-monsoon dynamics on the central Tibetan Plateau (China)

    NASA Astrophysics Data System (ADS)

    Kasper, T.; Haberzettl, T.; Daut, G.; Mäusbacher, R.; Wang, J.; Zhu, L.

    2011-12-01

    In previous studies Nam Co (Co=lake) was figured out to be a suitable site for monsoon reconstruction on the Tibetan Plateau (TP). Here we present first results from Tangra Yumco (4535 m a.s.l.; 31°06'N; 86°37'E; 818 km^2) which is the prerequisite resumption of an E-W transect across the TP to advance in the reconstruction of paleo-monsoon dynamics. Hydro-acoustic data were recorded at Tangra Yumco to gather information on the bathymetry as well as on the structure and thickness of the sediments. Sediment gravity cores were recovered from the deepest part of the lake. A multi-dating approach using radiocarbon dating and paleomagnetic measurements was applied to establish a reliable chronology. High-resolution XRF core-scans, radiographic imaging and grain size analyses were carried out. The N-S-oriented lake reveals two separate parts with different water depths of ~100 m in the South and ~220 m in the North. Seismic records show well layered deposits up to 25 m (no basement detected) within different acoustic units, slump- and tectonic structures as well as subaqueous lake-level terraces and beach berms/dunes down to 45 m below the recent lake level. On the other hand terraces of lake level high stands are evident up to ~205 m above the today's lake level. Within the recovered sediment records event layers are intercalated between finely laminated sediments. The processes causing these structures up to now are not completely understood, but might be linked to lake level variations (terrace formation), heavy rainfall events or even earthquakes as the lake is situated in a tectonic highly active area. The two sediment cores recovered from the northern part of the lake (TAN 10/1, 168 cm, western slope, ~180 m water depth; TAN 10/4, 163 cm, central basin, ~220 m water depth) were dated using bulk radiocarbon dating. A carbon-reservoir effect was determined to be ~2120 (+110/-90) years. This was obtained by dating the sediment surface at each coring site as well as

  5. First flush characteristics of rainfall runoff from a paddy field in the Taihu Lake watershed, China.

    PubMed

    Li, Songmin; Wang, Xiaoling; Qiao, Bin; Li, Jiansheng; Tu, Jiamin

    2017-02-06

    Nonpoint storm runoff remains a major threat to surface water quality in China. As a paddy matures, numerous fertilizers are needed, especially in the rainy seasons; the concentration of nitrogen and phosphorus in rainfall runoff from farmland is much higher than at other times, and this poses a great threat to water bodies and is the main reason for water eutrophication, especially in high concentration drainages. To date, most studies regarding the characteristics of pollutants in rainfall runoff have mainly been concentrated on urban runoff and watershed runoff; therefore, it is particularly important to investigate the characteristics of nitrogen and phosphorus loss in rainfall runoff from paddy fields. To study the characteristics of nitrogen and phosphorus loss and whether the first flush effect exists, continuous monitoring of the rainfall runoff process of six rainfall events was conducted in 2013, of which four rainfall events during storm, high, middle, and low intensity rainfalls were analyzed, and runoff and quality parameters, such as suspended solids (SS), total nitrogen (TN), ammonium nitrogen (NH4(+)-N), nitrate nitrogen (NO3(-)-N), total phosphorus (TP), and phosphate (PO4(3-)-P), were analyzed to determine the relationship between runoff and water quality. The paddy field is located north of Wuxi Lake Basin along the Hejia River upstream in Zhoutie town, Yixing city. An analysis of the load distribution during rainfall runoff was conducted. Event mean concentration (EMC) was used to evaluate the pollution situation of the paddy field's rainfall runoff. A curve of the dimensionless normalized cumulative load (L) vs. normalized cumulative flow (F) (L-F curve), the probability of the mass first flush (MFFn), and the pollutants carried by the initial 25% of runoff (FF25) were used to analyze the first flush effect of the paddy field runoff, and different contaminants show different results: the concentration of nitrogen and phosphorus fluctuate and

  6. Diagenetic effects on magnetic minerals in Holocene lacustrine sediments core from Huguangyan maar lake, southeast China

    NASA Astrophysics Data System (ADS)

    Wu, Xudong; Shen, Ji; Wang, Yong

    2017-04-01

    Grain size, rock magnetic and geochemical investigations on the entire core, as well as SEM observations and XRD analyses for representative samples were carried out on a Holocene sediment core from the deep part of Huguangyan maar lake (HGY), southeast China. The pristine magnetic mineral assemblage of the studied core has been profoundly modified by post-depositional reductive diagenesis. The studied core can be divided into three subsections based on down-core variations of the average grain size (MZ), total organic carbon (TOC), terrestrial elements (Al, Ti, Fe and Mn), and abundance and composition of magnetic minerals. The uppermost subsection has the lowest MZ values and TOC contents , but the highest detrital mineral input. Detrital magnetite is the main magnetic mineral in the uppermost subsection, which suggests minims of diagenetic modification of detrital magnetic minerals. The intermediate subsection is characterized by relatively higher MZ values and TOC contents, but relatively lower detrital mineral input compared to the uppermost subsection. The abundance and mineralogy of magnetic minerals in the intermediate subsection indicates progressive down-core dissolution of detrital magnetite, concomitant formation of authigenic siderite and iron sulphides, and hence a sustained down-core diagenetic modification of detrital iron bearing mineral assemblages. The lowermost subsection has the highest MZ values and TOC contents, but the lowest detrital mineral input. Detrital magnetite becomes scarce or absent at certain positions in the lowermost subsection, and gives way to authigenic iron sulphides and siderite. Complete dissolution of detrital magnetite and preservation of authigenic ferrimagnetic greigite in the lower part of the studied core could complicate or compromise palaeomagnetic studies. The studied core have undergone more severe diagenetic modification than two previously studied cores form relatively shallower part of HGY. It appears that

  7. Hydraulic connectivity and evaporation control the water quality and sources of chromophoric dissolved organic matter in Lake Bosten in arid northwest China.

    PubMed

    Zhou, Lei; Zhou, Yongqiang; Hu, Yang; Cai, Jian; Bai, Chengrong; Shao, Keqiang; Gao, Guang; Zhang, Yunlin; Jeppesen, Erik; Tang, Xiangming

    2017-12-01

    Lake Bosten is the largest oligosaline lake in arid northwestern China, and water from its tributaries and evaporation control the water balance of the lake. In this study, water quality and chromophoric dissolved organic matter (CDOM) absorption and fluorescence were investigated in different seasons to elucidate how hydraulic connectivity and evaporation may affect the water quality and variability of CDOM in the lake. Mean suspended solids and turbidity were significantly higher in the upstream tributaries than in the lake, the difference being notably more pronounced in the wet than in the dry season. A markedly higher mean first principal component (PC1) score, which was significantly positively related to protein-like components, and a considerably lower fluorescence peak integration ratio - IC:IT, indicative of the terrestrial humic-like CDOM contribution percentage, were observed in the lake than in the upstream tributaries. Correspondingly, notably higher contribution percentages of terrestrial humic-like components were observed in the river mouth areas than in the remaining lake regions. Furthermore, significantly higher mean turbidity, and notably lower mean conductivity and salinity, were recorded in the southwestern Kaidu river mouth than in the remaining lake regions in the wet season. Notably higher mean salinity is recorded in Lake Bosten than in upstream tributaries. Autochthonous protein-like associated amino-acids and also PC1 scores increased significantly with increasing salinity. We conclude that the dynamics of water quality and CDOM composition in remote arid Lake Bosten are strongly driven by evaporation and also the hydraulic connectivity between the upstream tributaries and the downstream lake. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. 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.

  9. 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.

  10. Spatial patterns of ice and snow storms disturbance on a subtropical forested landscape in the Poyang Lake region, southern China

    NASA Astrophysics Data System (ADS)

    Shi, L.

    2011-12-01

    In early 2008, an unexpected ice and snow storm (major freezing rain events) hit southern China, severely affected the subtropical forest ecosystems, especially in the Poyang Lake region. While plot and stand-scale ecological impacts of the 2008 storm have received attention, spatial heterogeneity of larger-extent damage has not been previously evaluated. The objective of this study is to investigate the spatial pattern of the 2008 ice and snow storm on subtropical forests and to analyze the effect of topography features (elevation, aspect and slope inclination) on the damage with remote sensing data in the Poyang Lake region. The Enhanced Vegetation Index (EVI) was employed to assess forest vigor and canopy density in atmospherically corrected Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery of study area. Digital change analysis of the baseline forest condition (2004 EVI data), and the condition encountered in a post-storm image (2008 EVI data) was conducted. The results display a northeast-to-southwest gradient and a gradient from the center to boundary of Poyang basin and Jitai basin in damage that apparently corresponds to a gradient in the depth of ice and snow that accumulated during the storms (Figure 1). Damage also varied topographically, particularly by elevation and slope in the Poyang Lake region. Topography affected patterns of ice and snow damages in study area with the greatest EVI losses occurring on north-, northeast- and east-facing (windward) slopes; and at middle elevations; and on slopes of moderate steepness. Unlike previous studies in North America that found damage was most extensive at middle elevations, EVI decrease associated with the 2008 storm was greater not only at the middle elevations (0.09), but also at the higher elevations (0.07) in the Poyang Lake region. This result suggests that subtropical forests are more vulnerable to ice and snow disturbance.

  11. 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.

  12. 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

  13. Spatiotemporal patterns of precipitation extremes in the Poyang Lake basin, China: Changing properties and causes

    NASA Astrophysics Data System (ADS)

    Xiao, M.

    2016-12-01

    Under the background of climate change, extensive attentions have been paid on the increased extreme precipitation from the public and government. To analyze the influences of large-scale climate indices on the precipitation extremes, the spatiotemporal patterns of precipitation extremes in the Poyang Lake basin have been investigated using the Bayesian hierarchical method. The seasonal maximum one-day precipitation amount (Rx1day) was used to represent the seasonal precipitation extremes. Results indicated that spring Rx1day was affected by El Niño/Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO), a positive ENSO event in the same year tends to decrease the spring Rx1day in the northern part of Poyang Lake Basin while increase the spring Rx1day in southeastern Poyang Lake Basin, a positive NAO events in the same year tends to increase the spring Rx1day in the southwest and northwest part of Poyang Lake basin while decrease the spring Rx1day in the eastern part of Poyang Lake basin; summer Rx1day was affected by Indian Ocean Dipole (IOD), positive IOD events in the same year tend to increase the summer Rx1day of northern Poyang Lake basin while decrease summer Rx1