A study about some physicochemical parameters of Egbe reservoir was carried out from September 2005 to December 2006. The parameters include mean temperature, pH, conductivity, alkalinity, TSS, TDS, DO and BOD which h...A study about some physicochemical parameters of Egbe reservoir was carried out from September 2005 to December 2006. The parameters include mean temperature, pH, conductivity, alkalinity, TSS, TDS, DO and BOD which have values of 28.7±0.9 ℃ ; 8.3±0.3; 831±172.5 μS/cm; 165.4±18.3 mg/L; 0.06±0.1 mg/L; 0.4±0.6 mg/L; 7.8±2.4 mg/L and 5.2±1.6mg/L, respectively. Temperature and pH were measured in the field using mercury-in-glass thermometer calibrated in degrees Celsius and pH meter, respectively. TSS and TDS were measured by grayimetric methods, while alkalinity was measured titrimetrically and DO and BOD were measured by Winkler＇s method. For the nutrients, nitrate was measured color±metrically, phosphate by Stannous Chloride method and sulphate by turbidimetric method. Mean concentration of nitrate, phosphate, and sulphate were 15.6±8.6 rag/L; 42.5±19.4 mg/L and 72.3±14.7 mg/L respectively. Nowadays, eutrophication of natural waters is one of the most significant causes of deterioration of water quality, and nitrates and phosphates are probably the key nutrients in controlling the growth of aquatic plants. Though the mean concentration of nitrates and phosphates in the reservoir water were within the acceptable limit, yet their concentrations in some locations of reservoir were high enough to encourage the growth of aquatic macrophytes which would increase productivities. Hence, it is necessary to check their further increase, and periodic monitoring and preventive measures must be adopted to save the reservoir from eutrophication.展开更多
Coated wire sensor for potentiometric determination ofDAP （dapoxetine HCI） in pure form and in biological fluidsbased on DAP-TPB （dapoxetine-tetraphenyl borate） as the sensing element in the presence of DOP （dioc...Coated wire sensor for potentiometric determination ofDAP （dapoxetine HCI） in pure form and in biological fluidsbased on DAP-TPB （dapoxetine-tetraphenyl borate） as the sensing element in the presence of DOP （dioctylphthalate） as the plasticizing solvent mediator was prepared. The best performance was obtained with a membrane composition of 10.0% （w/w） ion-pair, 45.0% DOP （w/w） and 45.0% PVC （w/w）. The electrode showed a Nemstian response （with a slope of 58.70 mV decade-1） for the concentration range of 4.2 × 10-5-1.0 ×10-2 mol/L. It illustrates a relatively fast response time in the whole concentration range （-15 s） in a pH range of 3.0-7.5. The selectivity coefficients were determined in relation to several inorganic and organic species. DAP is determined successfully in pure solutions and in biological fuids using the standard additions and petentiometric titrations methods.展开更多
The concentrations of phosphate （PO43 ）, ammonium, nitrite, nitrate, silicate, dissolved organic nitrogen （DON）, dissolved or- ganic phosphorus （DOP）, particulate phosphorus （PP） and particulate nitrogen （PN...The concentrations of phosphate （PO43 ）, ammonium, nitrite, nitrate, silicate, dissolved organic nitrogen （DON）, dissolved or- ganic phosphorus （DOP）, particulate phosphorus （PP） and particulate nitrogen （PN） along the salinity gradient were measured in the Changjiang Estuary in April 2007. The behavior of nutrient species along the continuum from the freshwater to the coastal zone is discussed. In the mixing zone between the riverine and marine waters, nitrate and phosphate behave non-conservatively, while silicate behaves conservatively. Nutrient import was quantified from the fiver load. Nutrient export to the sea was quantified from fiver discharge and from the salinity-nutrient gradient in the outer estuary. Using these data, a nitrogen and phosphorus budget was made. The internal estuarine fluxes played an important role in the nutrient estuarine fluxes, which accounted for approximately 41% of the nitrogen flux and 45% of the phosphorus flux. The mixing experiments in the laboratory generally reproduced well the inorganic process affecting nutrient dynamics in the Changjiang Estuary, indi- cating that the primary P and N transformation processes were phosphate and nitrate desorption along the salinity gradient.展开更多
文摘A study about some physicochemical parameters of Egbe reservoir was carried out from September 2005 to December 2006. The parameters include mean temperature, pH, conductivity, alkalinity, TSS, TDS, DO and BOD which have values of 28.7±0.9 ℃ ; 8.3±0.3; 831±172.5 μS/cm; 165.4±18.3 mg/L; 0.06±0.1 mg/L; 0.4±0.6 mg/L; 7.8±2.4 mg/L and 5.2±1.6mg/L, respectively. Temperature and pH were measured in the field using mercury-in-glass thermometer calibrated in degrees Celsius and pH meter, respectively. TSS and TDS were measured by grayimetric methods, while alkalinity was measured titrimetrically and DO and BOD were measured by Winkler＇s method. For the nutrients, nitrate was measured color±metrically, phosphate by Stannous Chloride method and sulphate by turbidimetric method. Mean concentration of nitrate, phosphate, and sulphate were 15.6±8.6 rag/L; 42.5±19.4 mg/L and 72.3±14.7 mg/L respectively. Nowadays, eutrophication of natural waters is one of the most significant causes of deterioration of water quality, and nitrates and phosphates are probably the key nutrients in controlling the growth of aquatic plants. Though the mean concentration of nitrates and phosphates in the reservoir water were within the acceptable limit, yet their concentrations in some locations of reservoir were high enough to encourage the growth of aquatic macrophytes which would increase productivities. Hence, it is necessary to check their further increase, and periodic monitoring and preventive measures must be adopted to save the reservoir from eutrophication.
文摘Coated wire sensor for potentiometric determination ofDAP （dapoxetine HCI） in pure form and in biological fluidsbased on DAP-TPB （dapoxetine-tetraphenyl borate） as the sensing element in the presence of DOP （dioctylphthalate） as the plasticizing solvent mediator was prepared. The best performance was obtained with a membrane composition of 10.0% （w/w） ion-pair, 45.0% DOP （w/w） and 45.0% PVC （w/w）. The electrode showed a Nemstian response （with a slope of 58.70 mV decade-1） for the concentration range of 4.2 × 10-5-1.0 ×10-2 mol/L. It illustrates a relatively fast response time in the whole concentration range （-15 s） in a pH range of 3.0-7.5. The selectivity coefficients were determined in relation to several inorganic and organic species. DAP is determined successfully in pure solutions and in biological fuids using the standard additions and petentiometric titrations methods.
基金supported by the National Basic Research Program of China(2011CB403602)National Natural Science Foundation of China(41276070,40920164004)National Natural Science Foundation for Creative Research Groups(41221004)
文摘The concentrations of phosphate （PO43 ）, ammonium, nitrite, nitrate, silicate, dissolved organic nitrogen （DON）, dissolved or- ganic phosphorus （DOP）, particulate phosphorus （PP） and particulate nitrogen （PN） along the salinity gradient were measured in the Changjiang Estuary in April 2007. The behavior of nutrient species along the continuum from the freshwater to the coastal zone is discussed. In the mixing zone between the riverine and marine waters, nitrate and phosphate behave non-conservatively, while silicate behaves conservatively. Nutrient import was quantified from the fiver load. Nutrient export to the sea was quantified from fiver discharge and from the salinity-nutrient gradient in the outer estuary. Using these data, a nitrogen and phosphorus budget was made. The internal estuarine fluxes played an important role in the nutrient estuarine fluxes, which accounted for approximately 41% of the nitrogen flux and 45% of the phosphorus flux. The mixing experiments in the laboratory generally reproduced well the inorganic process affecting nutrient dynamics in the Changjiang Estuary, indi- cating that the primary P and N transformation processes were phosphate and nitrate desorption along the salinity gradient.
