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۱Phytoplankton Community and the Relationship with the Environment in Nansi Lake, China
نویسنده(ها): ، ، ، ، ، ، ،
اطلاعات انتشار: International Journal Of Environmental Research، پنجم،شماره۱، Winter ۲۰۱۱، سال
تعداد صفحات: ۱۰
This study was carried out from June to October 2008 in Nansi Lake. Based on the data collected from five sampling stations, phytoplankton taxonomic composition, abundance, temporal variations and spatial distribution were examined. About 94 species, including 48 species of Chlorophyta, 22 species of Bacillariophyta, and 1 water bloom causative species were identified. Average phytoplankton diversity index and evenness values were 1.59 and 0.58, respectively, revealing moderate biodiversity of phytoplankton biocoenosis. The phytoplankton abundance averaged 1.52×107 cells\L, and was much higher than previous investigation carried out in the same months in 1995. The species of Chlorophyta, Bacillariophyta dominated phytoplankton community. The main dominant species were Scenedesmus dimorphus, Chlorella vulgaris, Synedra acus, Aulacoseira granulata, Merismopedia tenuissima and Monallantus brevicylindrus. Concerning nutrient stoichiometry, it was suggested that the higher TN: TP ratio indicated potential P–limitation for phytoplankton growth in Nansi Lake. The environmental conditions of water quality and phytoplankton community composition indicated that Nansi Lake was eutrophic in summer.

۲Performance of Kriging and EWPM for Relative Air Pollution Exposure Risk Assessment
نویسنده(ها): ، ، ، ، ، ، ، ، ،
اطلاعات انتشار: International Journal Of Environmental Research، پنجم،شماره۳، Summer ۲۰۱۱، سال
تعداد صفحات: ۱۰
This study investigates the effectiveness of the Kriging interpolation model and the Emission Weighted Proximity Model (EWPM) in assessing relative exposure risk of air pollution using results from the American Meteorological Society\EPA Regulatory Model (AERMOD) as benchmarks. We used simulated exposure risk to SO2 in the Dallas area in Texas in this evaluation. Results suggest that the relative exposure risks to SO2 at different locations in the study area as estimated by EWMP are closer to estimated risks from AERMOD when compared with the results calculated by Kriging. In addition, study results also indicate that the relative exposure risks calculated by Kriging are similar to those from AERMOD when the density of emission sources in the area in question is high. It is therefore concluded that relative exposure risks determined by both the Kriging interpolation method and the EWPM are acceptable when it is not possible to use AERMOD. In situations when the density of emission sources is low in the study area, EWPM is a better choice than Kriging.

۳Study on the Transport of Sediment Oxygen Demand –Related OrganicMatter in Bottom Sediment System
نویسنده(ها): ، ، ، ، ، ، ، ،
اطلاعات انتشار: International Journal Of Environmental Research، پنجم،شماره۳، Summer ۲۰۱۱، سال
تعداد صفحات: ۸
Approach of organic material anaerobic biodegradation and species of organic matter in sediment are discussed, and then a classifying method of the species is proposed on a new viewpoint. The pore water sediment oxygen demand (SOD) numerical model in bottom sediment system is proposed originally, which differs from other advection–dispersion–sorption (ADS) model in adding a SOD–creating term. The model was preliminarily validated via pilot experiment. Finally, this model was used to simulate SOD concentration of pore water in bottom sediment, and the sensitivity of parameters in the model was analyzed. The results indicate that SOD–creating factor at beginning stage and pore water SOD–attenuating factor in bottom sediment are the most important coefficients in the new model and should be estimated accurately. Because of the assumption of equilibrium of sorption\desorption, the new model appears to be valid only with less than 5 m\ d vertical velocity of pore water.

۴Study on the Transport of Sediment Oxygen Demand –Related OrganicMatter in Bottom Sediment System
نویسنده(ها): ، ، ، ، ، ، ، ،
اطلاعات انتشار: International Journal Of Environmental Research، پنجم،شماره۳، Summer ۲۰۱۱، سال
تعداد صفحات: ۸
Approach of organic material anaerobic biodegradation and species of organic matter in sediment are discussed, and then a classifying method of the species is proposed on a new viewpoint. The pore water sediment oxygen demand (SOD) numerical model in bottom sediment system is proposed originally, which differs from other advection–dispersion–sorption (ADS) model in adding a SOD–creating term. The model was preliminarily validated via pilot experiment. Finally, this model was used to simulate SOD concentration of pore water in bottom sediment, and the sensitivity of parameters in the model was analyzed. The results indicate that SOD–creating factor at beginning stage and pore water SOD–attenuating factor in bottom sediment are the most important coefficients in the new model and should be estimated accurately. Because of the assumption of equilibrium of sorption\desorption, the new model appears to be valid only with less than 5 m\ d vertical velocity of pore water.

۵Dissolved Organic Nitrogen (DON) in Full Scale Two–stage O3–BAC with Nitrate as Sole Inorganic Nitrogen Source
نویسنده(ها): ، ، ، ، ، ، ، ، ، ، ،
اطلاعات انتشار: International Journal Of Environmental Research، ششم،شماره۴، Autumn۲۰۱۲، سال
تعداد صفحات: ۱۰
Dissolved organic nitrogen (DON) can react with disinfectants to produce numerous disinfection byproducts (DBPs), particularly nitrogen–containing DBPs (N–DBPs), and produce serious adverse effects on public health. Widely used biological processes in drinking water treatment can increase DON in effluents, and enhance these ill effects. This study investigated DON in a full–scale two–stage ozonation–biological activated carbon (O3–BAC) filtration system. DON concentrations generally increased as media depth increased. There was an ebb and flow pattern between DON and NO3 –_N along the media depth in the absence of NH4 +_N and NO2 –_N. This suggests that NO3 –_N is the nitrogen source for DON. Ozonation and nutrient availability significantly impacted microbial biomass and microbial activity. Microbial biomass and microbial activity were both very important to DON formation as they affected the release of soluble microbial products (SMPs). Typical SMPs such as tyrosine\tryptophan amino acids and proteins were found to be formed during biofiltration, and this formation correlated well with DON from the same sampling ports. In order to balance the mass difference between the increased DON and disappeared NO3 –_N, a hypothesis on the generation and consumption equilibrium of DON and NO3 –_N was posited. This hypothesis involves the existence of nitrogen in the influent, effluent, and backwashing water, and the synthesis of said nitrogen by microorganisms.

۶Removal of Chelated Copper by TiO2 Photocatalysis: Synergetic Mechanism Between Cu (II) and Organic Ligands
نویسنده(ها): ، ، ، ، ، ، ، ، ،
اطلاعات انتشار: Iranian Journal of Chemistry and Chemical Engineering (IJCCE)، سي و دوم،شماره۱(پياپي ۶۵)، ۲۰۱۳، سال
تعداد صفحات: ۱۰
UV\TiO2 photocatalysis of chelated copper in aqueous solutions has been performed starting from Cu(II)–tartaric acid, Cu(II)–citric acid, Cu(II)–EDTA and Cu(II)–DTPA, in the presence of oxygen and at acidic pH. The photocatalytic reaction obeys first–order kinetic equation. The influence of Cu(II) on photocatalytic oxidation of organic ligands and how the various organics will affect the treatment of Cu(II) were described. A significant synergistic effect was observed between the reduction of Cu(II) and oxidation of organic ligands. The results prove that TiO2 photocatalysis is an effective approach for removing chelated copper from wastewater.
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