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Li Y.,Changan University | Li Y.,Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas | Li Y.,Harbin Institute of Technology | Yang L.,Changan University | And 3 more authors.
Aerosol and Air Quality Research | Year: 2013

To characterize the emission of microbial aerosols from the widely used municipal sewage treatment plants (MSTP) in China, an Andersen six-stage impactor and the culture method were employed to determine the concentrations and size distributions of airborne viable bacteria, fungi and actinomycetes in a sewage treatment plant with an oxidation ditch process in Xi'an in summer. The results showed that the concentrations and size distributions of each of the airborne microorganisms varied greatly at different phases of sewage treatment process. The highest bacteria (7866 ± 970 CFU/m3) and actinomycetes concentrations (2139 ± 229 CFU/m3) were found in the sludge-dewatering house while the highest fungi concentration (2156 ± 119 CFU/m3) at the oxidation ditch. The particle size distributions showed that similar single-peak pattern for airborne actinomycetes, bacteria and fungi. Another important finding was that about 52% of airborne bacteria, 62% of airborne fungi and 65% of airborne actinomycetes were in respirable size range (less than 3.3 μm), indicating that most microbial aerosols from MSTP could easily penetrate into the human alveolus. Finally, the order of the count median diameters of different microbial aerosols was found to be similar at each phase, that is, airborne bacteria > airborne fungi > airborne actinomycetes. This implied that airborne actinomycetes emitted from MSTP might have a more significant effect on public health and urban air quality than bacteria and fungi. © Taiwan Association for Aerosol Research. Source


Li Y.,Changan University | Li Y.,Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas | Zhang H.,Changan University | Qiu X.,Research Professional Committee of All China Environment Federation | And 2 more authors.
Aerosol and Air Quality Research | Year: 2013

A microbial risk assessment was carried out for the rotating-brush aerator used during summer in a wastewater treatment plant (WWTP) of Xi'an, China. Bacterial aerosols were first collected by an Andersen cascade impactor at selected sampling sites near the rotating-brush aerator. The concentrations of airborne bacteria were used to obtain microbial emission rate by back calculation. The downwind concentrations of airborne bacteria were then calculated by a modified Gaussian dispersion model accounting for environmental impact and microorganism decay. Subsequently, the exposure parameters suitable for Chinese people were incorporated into a risk assessment model to evaluate non-carcinogenic risks of airborne mesophilic bacteria to sewage workers and surrounding residents. The results indicate that both mean bacterial concentrations at ground level and the exposure hazard quotient decrease rapidly with downwind distance. The exposure hazard quotient by inhalation route is over 105 times more than by dermal contact route for both children and adults, suggesting that inhalation route is the major exposure pathway of microbial aerosol intake for surrounding people. Although the present model gives acceptable low risk values at various downwind distances, it is worth noting that health risks of microbial aerosols associated with rotating-brush aeration for children are generally much more than those for adults. © Taiwan Association for Aerosol Research. Source


Jing J.,Changan University | Hui Q.,Changan University | Hui Q.,Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas | Yu-Fei C.,Changan University | Wen-Juan X.,Changan University
Journal of Chemistry | Year: 2013

The basic theory and calculating processes of matter element extension method are discussed in detail. Mass balance simulation is used to study the changes of groundwater chemistry. Results show that calcite and dolomite are oversaturated, while gypsum, fluorite, and halite are unsaturated in the simulation path; so calcite precipitates, while gypsum, fluorite, halite, and dolomite dissolve. The changing tendency of Ca2+/Na+ is apparent. Because of the dissolution and precipitation of minerals, the content of each ion changes. Parameters of groundwater are basically within the permissible limits and meet the requirement of drinking water standards. By comparing the evaluation results obtained from matter element extension method, osculating value method based on entropy weight, and principal component analysis method, it is proved that matter element extension is an effective and reasonable method for groundwater quality assessment. The converting tendency of groundwater quality is judged based on the extension indexes; this characteristic is unique of matter element extension method. © 2013 Jin Jing et al. Source


Li P.,Changan University | Li P.,Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas | Wu J.,Changan University | Wu J.,Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas | And 2 more authors.
Environmental Earth Sciences | Year: 2013

Groundwater is an important water source for agricultural irrigation in Penyang County. Some traditional methods such as irrigation coefficient, sodium adsorption ratio, total alkalinity, total salinity and total dissolved solids were employed to assess groundwater quality in this area. In addition, an improved technique for order preference by similarity to ideal solution model was applied for comprehensive assessment. The origin of major ions and groundwater hydrogeochemical evolution was also discussed. Groundwater in Penyang County contains relative concentrations of dominant constituents in the following order: Na+ > Ca2+ > Mg2+ > K+ for cations and HCO3 - > SO4 2- > Cl- > CO3 2- for anions. Groundwater quality is largely excellent and/or good, suggesting general suitability for agricultural use. Calcite and dolomite are found saturated in groundwater and thus tend to precipitate out, while halite, fluorite and gypsum are unsaturated and will dissolve into groundwater during flow. Groundwater in the study area is weathering-dominated, and mineral weathering (carbonate and silicate minerals) and ion exchange are the most important factors controlling groundwater chemistry. © 2012 Springer-Verlag Berlin Heidelberg. Source


Li P.,Changan University | Li P.,Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas | Qian H.,Changan University | Qian H.,Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas | And 2 more authors.
Hydrological Processes | Year: 2014

Accurate knowledge of hydrogeological parameters is essential for groundwater modeling, protection and remediation. Three methods (type curve fitting method, inflection point method and global curve-fitting method (GCFM)) which are frequently applied in the estimation of leaky aquifer parameters were compared using synthetic pumping tests. The results revealed GCFM could provide best parameter estimation among the three methods with fewer uncertainties associated with the processes of parameter estimation. GCFM was also found to be both time saving and of low cost and is thus more preferable for hydrogeological parameter estimation than the other two methods. © 2013 John Wiley & Sons, Ltd. Source

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