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Junting M.,Nanjing Normal University | Suozhong C.,Jiangsu Center for Collab. Innovation in Geographical Information Resource Development and Application | Zhichao H.,Nanjing Normal University | Xiaoting Z.,Nanjing Normal University
Nature Environment and Pollution Technology | Year: 2017

The space structure of aquifer (group) does not only determine the spatial distribution pattern of groundwater, but also impose some effects on the groundwater quality. Based on the internal hydrogeological borehole data in hydrogeological division of Yancheng Coastal Plain and water quality factor monitoring data during 2005~2014, geographic information science (GIS) and analysis of variance (ANOVA) method etc., are applied to the research response characteristics of aquifer roof depth changes in time-space dimension for the quality of porous groundwater of confined aquifer III in experiment sample area. This paper analyses the dynamic evolution laws of groundwater quality and proposes suggestions on groundwater management and protection in the research area. The research result shows that the depth of confined aquifer III in this area mostly goes between -118.9 ~-85.45 m. Due to hydrogeological conditions of groundwater with different depths and exploitation and utilization differences, there is some correlation between a typical water quality factor of groundwater and aquifer depth. Mineralization, total alkalinity and total bacterial count have the strongest correlation strength with the depth (relevancy: 69.67 %, 75.76 % and 58.09 %). The strength of total hardness is at an intermediate level (49.18 %). KMnO4 index is less affected by the depth (35.27 %). It is also found that the correlation strengths between factors and depth in various depth classification areas are significantly different, indicating different dynamic evolution characteristics.

Wang Q.,Nanjing Normal University | Wang Q.,CAS Institute of Earth Environment | Song Y.,CAS Institute of Earth Environment | Zhao Z.,Jiangsu Center for Collab. Innovation in Geographical Information Resource Development and Application | Li J.,Nanjing Normal University
Journal of Asian Earth Sciences | Year: 2016

The soil color is widely used in paleoclimate and paleoenvironment reconstructions in the Chinese Loess Plateau. To better understand the color spatial changes during the glacial-interglacial cycle, the soil color lightness (L*), characteristic spectra, magnetic susceptibilities and mean grain sizes of three loess-paleosol sequences were compared. Results showed that high L* and low hematite to goethite ratios (Hm/Gt) appeared in loess units, and low L* and high Hm/Gt ratios accompanied paleosol layers, indicating glacial-interglacial hydrothermal oscillation. L* in the Yulin section was higher than in the Chaona and Lihuacun sections, indicating that different precipitations have great effect on L*. Furthermore, Hm/Gt, magnetic susceptibility (χlf), and mean grain size are correlated closely with L*. L* and Hm/Gt not only document climatic variations in the glacial-interglacial cycle vis-à-vis loess-paleosol sequences, but also can identify Heinrich cold events and millennial scale Dansgaard-Oeschger (D-O) warm events. It suggests that soil color responds sensitively to global climate change driven by ice volumes. L* and Hm/Gt curves exhibit higher frequencies and larger amplitudes than magnetic susceptibility (χlf) curves, indicating that L* and Hm/Gt can be regarded as sensitive and reliable proxies for characterizing high-resolution climate change during the last glacial-interglacial cycle. © 2015 Elsevier Ltd.

Shi K.,CAS Nanjing Institute of Geography and Limnology | Zhang Y.,CAS Nanjing Institute of Geography and Limnology | Xu H.,CAS Nanjing Institute of Geography and Limnology | Zhu G.,CAS Nanjing Institute of Geography and Limnology | And 7 more authors.
Environmental Science and Technology | Year: 2015

Microcystins (MCs) produced by cyanobacteria pose a serious threat to public health. Intelligence on MCs distributions in freshwater is therefore critical for environmental agencies, water authorities, and public health organizations. We developed and validated an empirical model to quantify MCs in Lake Taihu during cyanobacterial bloom periods using the atmospherically Rayleigh-corrected moderate resolution imaging spectroradiometer (MODIS-Aqua) (Rrc) products and in situ data by means of chlorophyll a concentrations (Chla). First, robust relationships were constructed between MCs and Chla (r = 0.91; p < 0.001; t-test) and between Chla and a spectral index derived from Rrc (r = -0.86; p < 0.05; t-test). Then, a regional algorithm to analyze MCs in Lake Taihu was constructed by combining the two relationships. The model was validated and then applied to an 11-year series of MODIS-Aqua data to investigate the spatial and temporal distributions of MCs. MCs in the lake were markedly variable both spatially and temporally. Cyanobacterial bloom scums, temperature, wind, and light conditions probably affected the temporal and spatial distribution of MCs in Lake Taihu. The findings demonstrate that remote sensing reconnaissance in conjunction with in situ monitoring can greatly aid MCs assessment in freshwater. © 2015 American Chemical Society.

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