To gain a better understanding of water quality and eutrophication, we investigated the seasonal and spatial distribution of water quality at 17 stations in the Guangzhou Sea Zone （GZSZ）. Nutrients, chlorophyll-a （...To gain a better understanding of water quality and eutrophication, we investigated the seasonal and spatial distribution of water quality at 17 stations in the Guangzhou Sea Zone （GZSZ）. Nutrients, chlorophyll-a （Chl-a）, salinity, chemical parameters were determined in February, May, oxygen demand, and other physical and chemical August and October from 2005 to 2007. The concentrations showed ranges of 93.2-530.4 μmol/L for dissolved inorganic nitrogen （DIN）, 0.62-3.16 μmol/L for phosphate （PO4-P） and 50-127 μmol/L for silicate （SiO3-Si）, The results indicated that DIN was strongly influenced by domestic sewage coming from Guangzhou City and NO3-N was the main form of DIN in most areas, while concentrations of phosphate and silicate were generally controlled by Pearl River runoff, land-based sources along the land or islands, and algae assimilation. N/P ratios were very high in both dry season and wet season, and varied from 57 to 667, suggesting that P was potentially the most limiting nutrient in the GZSZ. The concentrations of Chl-a were 3-96 μg/L, and were highly correlated with the distribution characteristics of COD, The concentrations of nutrients have increased over the past two decades （1982-2007）. This means it is necessary to control the input of nutrients to the GZSZ, especially that of phosphate.展开更多
This research studied a new spectrophotometric method for measuring the chemical oxygen demand （COD） of seawater. In this method, the COD was measured using a spectrophotometer instead of titrating with sodium thios...This research studied a new spectrophotometric method for measuring the chemical oxygen demand （COD） of seawater. In this method, the COD was measured using a spectrophotometer instead of titrating with sodium thiosuiphate. The measuring wavelength was selected to be 470 nm, and the COD of three standard glucose solutions （COD = 0.5, 1.5 and 2.5 mgL^-1, respectively） and two seawater samples （from the South Yellow Sea and Jiaozhou Bay） were measured using the spectrophotometric method and titrimetric method respectively. The results showed that the spectrophotometric method was somewhat better than the titrimetric method. The relative standard deviation （RSD） of the spectrophotometric method was less than 2.7%, and the recovery of seawater samples ranged from 96.3% to 103.8%. In addition, the spectrophotometric method has other advantages such as expeditiousness, operation simplicity, analysis automatization, etc. Therefore the spectrophotometric method can be used to measure the COD of seawater with satisfactory results.展开更多
基金Supported by Key Innovation Project of Chinese Academy of Sciences (Nos. KZCX2-YW-Q07 and KZCX2-YW-213)the GD Projects of the National Natural Science Foundation of China (No. U0633007)
文摘To gain a better understanding of water quality and eutrophication, we investigated the seasonal and spatial distribution of water quality at 17 stations in the Guangzhou Sea Zone （GZSZ）. Nutrients, chlorophyll-a （Chl-a）, salinity, chemical parameters were determined in February, May, oxygen demand, and other physical and chemical August and October from 2005 to 2007. The concentrations showed ranges of 93.2-530.4 μmol/L for dissolved inorganic nitrogen （DIN）, 0.62-3.16 μmol/L for phosphate （PO4-P） and 50-127 μmol/L for silicate （SiO3-Si）, The results indicated that DIN was strongly influenced by domestic sewage coming from Guangzhou City and NO3-N was the main form of DIN in most areas, while concentrations of phosphate and silicate were generally controlled by Pearl River runoff, land-based sources along the land or islands, and algae assimilation. N/P ratios were very high in both dry season and wet season, and varied from 57 to 667, suggesting that P was potentially the most limiting nutrient in the GZSZ. The concentrations of Chl-a were 3-96 μg/L, and were highly correlated with the distribution characteristics of COD, The concentrations of nutrients have increased over the past two decades （1982-2007）. This means it is necessary to control the input of nutrients to the GZSZ, especially that of phosphate.
文摘This research studied a new spectrophotometric method for measuring the chemical oxygen demand （COD） of seawater. In this method, the COD was measured using a spectrophotometer instead of titrating with sodium thiosuiphate. The measuring wavelength was selected to be 470 nm, and the COD of three standard glucose solutions （COD = 0.5, 1.5 and 2.5 mgL^-1, respectively） and two seawater samples （from the South Yellow Sea and Jiaozhou Bay） were measured using the spectrophotometric method and titrimetric method respectively. The results showed that the spectrophotometric method was somewhat better than the titrimetric method. The relative standard deviation （RSD） of the spectrophotometric method was less than 2.7%, and the recovery of seawater samples ranged from 96.3% to 103.8%. In addition, the spectrophotometric method has other advantages such as expeditiousness, operation simplicity, analysis automatization, etc. Therefore the spectrophotometric method can be used to measure the COD of seawater with satisfactory results.
