Piper (1944) diagram has been the basis for several important interpretations of the hydrogeochemical data. As seen in this diagram, most natural waters contain relatively few dissolved constituents, with cations (met...Piper (1944) diagram has been the basis for several important interpretations of the hydrogeochemical data. As seen in this diagram, most natural waters contain relatively few dissolved constituents, with cations (metals or bases) and anions (acid radicles) in chemical equilibrium with one another. Apart from the facies representation, the composition of the mixed sample can be identified in terms of the composition of the parental solution. To bring out this advantage of the Piper diagram, a study was conducted in the Kalpakkam region of Tamilnadu, South India. By taking the geology and water table into consideration, two sample locations were selected as parent solution and third one as the mixture sample. All three samples were analyzed for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), chloride (Cl), sulphate (SO4) and phosphate (PO4) by Ion Chromatograph (Metrohm IC 861). HCO3 was determined by volumetric titration. The Piper diagram shows that parent solutions clustered towards Na-Mg-Ca-HCO3-Cl and Na-HCO3 facies, and the mixing sample belongs to Na-Mg-HCO3 facies. Phreeqc interac-tive (Ver 2.8) along with the original composition of the mixture sample was used to correlate the mixing proportion identified by the Piper diagram.展开更多
To reveal the basic characteristics and controlling factors of water quality change in the project Wenyu to Chaobai reclaimed water diversion, the water quality in the study area was monitored for one year at seven mo...To reveal the basic characteristics and controlling factors of water quality change in the project Wenyu to Chaobai reclaimed water diversion, the water quality in the study area was monitored for one year at seven monitoring sites. Inverse geochemical models of the statistical groups were developed using PHREEQC to elucidate the hydrochemistry characteristics of reclaimed water and the factors. The monitoring results indicated that nitrogen and phosphorus contents were significantly reduced along the river mainly caused by seasonal and location variation. The pH ranged from 7.44 to 9.81. Photosynthesis of algae and denitrification in anaerobic microenvironment ultimately led to a sudden pH increase after the Jian River and the Chaobai River confluence. Mg2＋ and SO^- levels dropped obviously in the summer and increased in winter seasons after intersection. Na＋ and C1- are relatively stable, and marked drop in the concentration only after the two rivers meet. And there is a decrease of Ca2＋ and HCO~ and increase in CO^- during monitoring period. As a whole, the primary ions and nutrient components, including nitrogen and phosphorus, had high levels in winter. Algae＇s photosynthesis and respiration were observed to have an impact on the river water quality; there was precipitation-dissolution of minerals and denitrification from upstream to downstream. Inverse geochemical PHREEQC modeling confirmed that there was precipitation of aragonite or calcite, and gypsum or anhydrite in summer, and dissolution in winter; as well as precipitation of dolomite in winter, and cationic exchange and denitrification along the river.展开更多
Arsenic（As）-contaminated wastewater and groundwater pose a pressing environmental issue and worldwide concern. Adsorption of As using TiO_2materials, in combination with filtration,introduces a promising technology ...Arsenic（As）-contaminated wastewater and groundwater pose a pressing environmental issue and worldwide concern. Adsorption of As using TiO_2materials, in combination with filtration,introduces a promising technology for the treatment of As-contaminated water. This review presents an overview on the recent progress of the application of TiO_2for removal of As from wastewater and groundwater. The main focus is on the following three pressing issues that limit the field applications of TiO_2for As removal： coexisting ions, simulation of breakthrough curves, and regeneration and reuse of spent TiO_2materials. We first examined how the coexisting ions in water, especially high concentrations of cations in industrial wastewater,affect the efficacy of As removal using the TiO_2materials. We then discussed As breakthrough curves and the effect of compounded ions on the breakthrough curves. We successfully simulated the breakthrough curves by PHREEQC after integrating the CD-MUSIC model. We further discussed challenges facing the regeneration and reuse of TiO_2media for practical applications. We offer our perspectives on remaining issues and future research needs.展开更多
文摘Piper (1944) diagram has been the basis for several important interpretations of the hydrogeochemical data. As seen in this diagram, most natural waters contain relatively few dissolved constituents, with cations (metals or bases) and anions (acid radicles) in chemical equilibrium with one another. Apart from the facies representation, the composition of the mixed sample can be identified in terms of the composition of the parental solution. To bring out this advantage of the Piper diagram, a study was conducted in the Kalpakkam region of Tamilnadu, South India. By taking the geology and water table into consideration, two sample locations were selected as parent solution and third one as the mixture sample. All three samples were analyzed for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), chloride (Cl), sulphate (SO4) and phosphate (PO4) by Ion Chromatograph (Metrohm IC 861). HCO3 was determined by volumetric titration. The Piper diagram shows that parent solutions clustered towards Na-Mg-Ca-HCO3-Cl and Na-HCO3 facies, and the mixing sample belongs to Na-Mg-HCO3 facies. Phreeqc interac-tive (Ver 2.8) along with the original composition of the mixture sample was used to correlate the mixing proportion identified by the Piper diagram.
基金supported by the Chinese National Environmental Protection Public Welfare Industry Targeted Research Fund (No. 201309001)the Fundamental Research Funds for the Central Universities (No. 53200859462)
文摘To reveal the basic characteristics and controlling factors of water quality change in the project Wenyu to Chaobai reclaimed water diversion, the water quality in the study area was monitored for one year at seven monitoring sites. Inverse geochemical models of the statistical groups were developed using PHREEQC to elucidate the hydrochemistry characteristics of reclaimed water and the factors. The monitoring results indicated that nitrogen and phosphorus contents were significantly reduced along the river mainly caused by seasonal and location variation. The pH ranged from 7.44 to 9.81. Photosynthesis of algae and denitrification in anaerobic microenvironment ultimately led to a sudden pH increase after the Jian River and the Chaobai River confluence. Mg2＋ and SO^- levels dropped obviously in the summer and increased in winter seasons after intersection. Na＋ and C1- are relatively stable, and marked drop in the concentration only after the two rivers meet. And there is a decrease of Ca2＋ and HCO~ and increase in CO^- during monitoring period. As a whole, the primary ions and nutrient components, including nitrogen and phosphorus, had high levels in winter. Algae＇s photosynthesis and respiration were observed to have an impact on the river water quality; there was precipitation-dissolution of minerals and denitrification from upstream to downstream. Inverse geochemical PHREEQC modeling confirmed that there was precipitation of aragonite or calcite, and gypsum or anhydrite in summer, and dissolution in winter; as well as precipitation of dolomite in winter, and cationic exchange and denitrification along the river.
基金supported by the National Basic Research Program (973) of China (No. 2015CB932003)the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB14020201)the National Natural Science Foundation of China (Nos. 41373123, 41425016, and 21321004)
文摘Arsenic（As）-contaminated wastewater and groundwater pose a pressing environmental issue and worldwide concern. Adsorption of As using TiO_2materials, in combination with filtration,introduces a promising technology for the treatment of As-contaminated water. This review presents an overview on the recent progress of the application of TiO_2for removal of As from wastewater and groundwater. The main focus is on the following three pressing issues that limit the field applications of TiO_2for As removal： coexisting ions, simulation of breakthrough curves, and regeneration and reuse of spent TiO_2materials. We first examined how the coexisting ions in water, especially high concentrations of cations in industrial wastewater,affect the efficacy of As removal using the TiO_2materials. We then discussed As breakthrough curves and the effect of compounded ions on the breakthrough curves. We successfully simulated the breakthrough curves by PHREEQC after integrating the CD-MUSIC model. We further discussed challenges facing the regeneration and reuse of TiO_2media for practical applications. We offer our perspectives on remaining issues and future research needs.
