CAS Nanjing Institute of Geography and Limnology

Nanjing, China

CAS Nanjing Institute of Geography and Limnology

Nanjing, China

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Su W.,CAS Nanjing Institute of Geography and Limnology
Frontiers of Earth Science | Year: 2017

There is growing interest in using the urban landscape for stormwater management studies, where land patterns and processes can be important controls for the sustainability of urban development and planning. This paper proposes an original index of Major Hazard Oriented Level (MHOL) and investigates the structure distribution, driving factors, and controlling suggestions of urban-rural land growth in flood-prone areas in the Taihu Lake watershed, China. The MHOL of incremental urban-rural land increased from M 31.51 during the years 1985–1995 to M 38.37 during the years 1995–2010 (M for medium structure distribution, and the number for high-hazard value). The index shows that urban-rural land was distributed uniformly in flood hazard levels and tended to move rapidly to high-hazard areas, where 72.68% of incremental urban-rural land was aggregated maximally in new urban districts along the Huning traffic line and the Yangtze River. Thus, the current accelerating growth of new urban districts could account for the ampliative exposure to high-hazard areas. New districts are driven by the powerful link between land financial benefits and political achievements for local governments and the past unsustainable process of “single objective” oriented planning. The correlation categorical analysis of the current development intensity and carrying capacity of hydrological ecosystems for sub-basins was used to determine four types of development areas and provide decision makers with indications on the future watershed-scale subdivision of Major Function Oriented Zoning implemented by the Chinese government. © 2017 Higher Education Press and Springer-Verlag Berlin Heidelberg

Xu X.,CAS Nanjing Institute of Geography and Limnology | Tan Y.,University of Adelaide | Yang G.,CAS Nanjing Institute of Geography and Limnology
Earth-Science Reviews | Year: 2013

The paper takes China's authoritative Environmental Impact Statement for the Yangzi (Yangtze) Three Gorges Project (TGP) in 1992 as a benchmark against which to evaluate emerging major environmental outcomes since the initial impoundment of the Three Gorges reservoir in 2003. The paper particularly examines five crucial environmental aspects and associated causal factors. The five domains include human resettlement and the carrying capacity of local environments (especially land), water quality, reservoir sedimentation and downstream riverbed erosion, soil erosion, and seismic activity and geological hazards. Lessons from the environmental impact assessments of the TGP are: (1) hydro project planning needs to take place at a broader scale, and a strategic environmental assessment at a broader scale is necessary in advance of individual environmental impact assessments; (2) national policy and planning adjustments need to react quickly to the impact changes of large projects; (3) long-term environmental monitoring systems and joint operations with other large projects in the upstream areas of a river basin should be established, and the cross-impacts of climate change on projects and possible impacts of projects on regional or local climate considered. © 2013 Elsevier B.V.

Xu H.,CAS Nanjing Institute of Geography and Limnology | Cai H.,CAS Nanjing Institute of Geography and Limnology | Yu G.,Nanjing Agricultural University | Jiang H.,CAS Nanjing Institute of Geography and Limnology
Water Research | Year: 2013

Investigations on the extracellular polymeric substances (EPS) are crucial for better understanding the growth and proliferation of cyanobacterium Microcystis aeruginosa. In this study, a combined approach of fractionation procedure and parallel factor (PARAFAC) analysis were applied to characterize the EPS of M. aeruginosa. Physicochemical analysis showed that the contents of polysaccharides in EPS matrix were higher than those of proteins, regardless of the differences in growth phases and nutritional levels in medium. Organic matters were mainly distributed in the tightly bound EPS (TB-EPS) fraction during the exponential growth phase, whereas they sharply released to the soluble EPS (SL-EPS) and loosely bound EPS (LB-EPS) fractions at the decay period. Fluorescence excitation-emission matrix (EEM) was applied to characterize the specific compositions in EPS matrix, and all the fluorescence EEM spectra collected could be successfully decomposed into a four-component model by PARAFAC analysis. Component 1 [excitation/emission (Ex/Em) = 220/340], component 2 (Ex/Em = 280/340) and component 3 [Ex/Em = (200, 220, 270)/296] were attributed to protein-like substances, while component 4 [Ex/Em = (250, 340)/438] belonged to humic-like substances. Pearson correlation analysis demonstrated that tryptophan-like substances in the LB-EPS and TB-EPS fractions were positively correlated with Microcystis growth, whereas in the SL-EPS fraction, tryptophan-like as well as humic-like substances were associated with the growth of M. aeruginosa. The scientific implication for Microcystis growth and proliferation, based on the results of fractionation procedure and EEM-PARAFAC analysis, was also presented. © 2013 Elsevier Ltd.

Xu H.,CAS Nanjing Institute of Geography and Limnology | Xu H.,Nanjing University | Jiang H.,CAS Nanjing Institute of Geography and Limnology
Water Research | Year: 2013

Cyanobacterial blooms represent a significant ecological and human health problem worldwide. In aquatic environments, cyanobacterial blooms are actually surrounded by dissolved organic matter (DOM) and attached organic matter (AOM) that bind with algal cells. In this study, DOM and AOM fractionated from blooming cyanobacteria in a eutrophic freshwater lake (Lake Taihu, China) were irradiated with a polychromatic UV lamp, and the photochemical heterogeneity was investigated using fluorescence excitation-emission matrix (EEM)-parallel factor (PARAFAC) analysis and synchronous fluorescence (SF)-two dimensional correlation spectroscopy (2DCOS). It was shown that a 6-day UV irradiation caused more pronounced mineralization for DOM than AOM (59.7% vs. 41.9%). The EEM-PARAFAC analysis identified one tyrosine-, one humic-, and two tryptophan-like components in both DOM and AOM, and high component photodegradation rates were observed for DOM versus AOM (. k>0.554 vs. <0.519). Moreover, SF-2DCOS found that the photodegradation of organic matters followed the sequence of tyrosine-like>humic-like>tryptophan-like substances. Humic-like substances promoted the indirect photochemical reactions, and were responsible for the higher photochemical rate for DOM. The lower photodegradation of AOM benefited the integrality of cells in cyanobacterial blooms against the negative impact of UV irradiation. Therefore, the photochemical behavior of organic matter was related to the adaptation of enhanced-duration cyanobacterial blooms in aquatic environments. © 2013 Elsevier Ltd.

Wu G.,CAS Nanjing Institute of Geography and Limnology | Liu Y.,CAS Nanjing Institute of Geography and Limnology
Journal of Hydrology | Year: 2015

Poyang Lake is the largest freshwater lake in China, with high morphological complexity from south to north. In recent years, the lake has experienced expansion and shrinkage processes over both short- and long-term scales, resulting in significant hydrological, ecological and economic problems. Exactly how and how rapidly the processes of spatial change have occurred in the lake during the expansion and shrinkage periods is unknown. Such knowledge is of great importance for policymakers as it may help with flood/drought prevention, land use planning and lake ecological conservation. In this study, we investigated the spatial-temporal distribution and changing processes of inundation in Poyang Lake based on Moderate Resolution Imaging Spectroradiometer (MODIS) Level-1B data from 2000 to 2011. A defined water variation rate (WVR) and inundation frequency (IF) indicator revealed the water surface submersion and exposure processes of lake expansion and shrinkage in different zones which were divided according to the lake's hydrological and topographic features. Regional differences and significant seasonality variability were found in the annual and monthly mean IF. The monthly mean IF increased slowly from north to south during January-August but decreased quickly from south to north during September-December. During the lake expansion period, the lake-type water body zone (Zone II) had the fastest expansion rate, with a mean monthly WVR value of 34.47% in February-March, and was followed by the channel-type water body zone (Zone I) in March-May (22.47%). However, during the lake shrinkage period, rapid shrinkage first appeared around the alluvial delta zones in August-October. The sequence of lake surface shrinkage from August to December is exactly opposite to that of lake expansion from February to July. These complex inundation characteristics and changing process were driven by the high temporal variability of the river flows, the morphological diversity of the benthic landforms and the patterns of water movement. These results provide a foundation for basic hydrological and ecological studies and are valuable for the conservation and management of water resources in Poyang Lake. © 2015 Elsevier B.V.

Liu Y.,CAS Nanjing Institute of Geography and Limnology | Wu G.,CAS Nanjing Institute of Geography and Limnology | Zhao X.,CAS Nanjing Institute of Geography and Limnology
Environmental Research Letters | Year: 2013

Poyang Lake is China's largest freshwater lake with a high degree of spatio-temporal variation. The lake has shrunk in size in recent years, resulting in significant hydrological, ecological and economic consequences. It remains unknown whether the shrinkage is a trend or a regime shift, which is of high importance for policymakers as it may lead to different decisions. This study constructed a four-decade record of the lake area using multi-temporal satellite images and hydrological data. The Mann-Kendall analysis revealed a decreasing trend of Poyang Lake but it was statistically insignificant. The Rodionov sequential approach disclosed an abrupt change of the lake in 2006, implying a regime shift. Basically, the lake change was a synthetic result of precipitation, evapotranspiration and outflow discharge. However, precipitation and outflow did not show any significant trend or abrupt change, and evapotranspiration had an increasing trend in addition to an abrupt change in 1998. The trigger for the recent lake declines was principally ascribed to a weakened blocking effect of the Yangtze River. The findings provide an example of hydrologic non-stationarity and are valuable for effective promotion of climate adaptation and water resource management. © 2013 IOP Publishing Ltd.

Song T.-S.,CAS Nanjing Institute of Geography and Limnology | Jiang H.-L.,CAS Nanjing Institute of Geography and Limnology
Bioresource Technology | Year: 2011

In the present study, the effects of different pretreatment methods for sediments on the performance of sediment microbial fuel cells (SMFCs) were evaluated. Autoclaved (30 and 60min), and heated (150°C, 3h) sediments demonstrated high power density, compared with control and heated (60°C, 3h) sediments. An SMFC with heated (60°C, 3h) sediment was found to easily form a biocathode. The power density of an SMFC with heated (150°C, 3h) sediment was 214mWm -2 on day 24. Furthermore, autoclaved (30 and 60min) and heated (3h, 60 and 150°C) sediments accelerated the production of dissolved organic matter (DOM). The DOM in heated (60°C, 3h) sediments had larger molecular sizes. The present study demonstrates that SMFCs can have high power density and high loss on ignition removal efficiencies when produced from sediments by suitable pretreatment methods. © 2011 Elsevier Ltd.

Qin B.,CAS Nanjing Institute of Geography and Limnology
Lake and Reservoir Management | Year: 2013

Qin B. 2013. A large-scale biological control experiment to improve water quality in eutrophic Lake Taihu, China. Lake Reserv Manage. 29:33-46. Lake eutrophication is one of the biggest environmental problems facing China. Since the mid-1990s, macrophyte restoration has been proposed and widely promoted as an affordable ecological solution. To assess the efficacy of this in-lake approach, an ecological engineering experimentwas conducted in large, shallow, eutrophic Lake Taihu, China, from 2003 to 2006 that combined physical and biological clarifying measures targeted at improving water quality for the drinkingwater supply. An experimental area of 7 km2was enclosed by a soft curtain to isolate it from the open lake and to block algal blooms. Inside this experimental area, around the intake of the waterworks, a 2 km2 inner enclosure was created with another soft curtain to promote the restoration of submersed and floating-leaf macrophytes intended to reduce nutrient loading inside the enclosure. Concrete pilings along the inner soft curtain protected it from wave action, and 945 bamboo rafts were deployed around the intake of thewaterworks forwave control and floatingmacrophyte cultivation. Herbivorous fish and shellfish were introduced into the outer enclosure to reduce phytoplankton biomass. Monthly water quality monitoring before and after the clarifying measures suggested no significant difference in water clarity in the inner enclosure. The intended macrophyte-dominant system in the inner enclosure did not emerge during the experiment, which might be associated with high nutrient levels and low transparency. Following this experiment, eutrophic lake restoration in China has shifted to control of pollutant effluents entering lakes. © by the North American Lake Management Society 2013.

Duan H.,CAS Nanjing Institute of Geography and Limnology | Ma R.,CAS Nanjing Institute of Geography and Limnology | Hu C.,University of South Florida
Remote Sensing of Environment | Year: 2012

Using reflectance data and water sample data from 75 stations in several eutrophic lakes of East China (Lake Taihu, Lake Gehu, Lake Dongjiu) between 23 April and 3 May 2010, we evaluated several recently proposed remote sensing algorithms to estimate chlorophyll-a concentrations (Chla, 1.0-42μg/L) and phycocyanin pigment concentrations (PC, 0.1-7.7μg/L). These lakes experience phytoplankton blooms of the cyanobacteria Microcystis aeruginosa every year due to eutrophication. It was found that after local tuning of the algorithm parameterizations, most algorithms yielded acceptable results for Chla retrievals while accurate PC retrievals were more challenging due to changing species composition (PC:Chla ratios) and low PC concentrations. For the data ranges in the study region, the best Chla algorithm yielded RMSE rel (Relative Root Mean Square Error) of ~46% (R 2=0.92, n=75) and the best PC algorithm yielded RMSE rel of ~83% (R 2=0.88, n=75). Based on these observations, it is recommended that local tuning of algorithm parameters should be performed for remote sensing applications, and future efforts should emphasize on application of the algorithms to satellite data. © 2012 Elsevier Inc.

Zeng H.,CAS Nanjing Institute of Geography and Limnology | Wu J.,CAS Nanjing Institute of Geography and Limnology
International Journal of Environmental Research and Public Health | Year: 2013

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. © 2013 by the authors.

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