Phosphorus （P） is an essential nutrient utilized by all organisms for energy transport and growth. Both the conventional molybdenum-blue method and the magnesium-induced coprecipitation （MAGIC） procedures were app...Phosphorus （P） is an essential nutrient utilized by all organisms for energy transport and growth. Both the conventional molybdenum-blue method and the magnesium-induced coprecipitation （MAGIC） procedures were applied for the measurement of dissolved inorganic phosphorus （DIP） and total dissolved phosphorus （TDP） in more than 840 water samples collected between 2003 and 2005, including seawater （the Huanghai Sea, the East China Sea, and the northern South China Sea）, water from rivers and estuaries （the Changjiang, the Huanghe, and the major rivers emptying into the Jiaozhou Bay）, groundwater （in the drainage basin surrounding the Jiaozhou Bay）, rain-water, and aquaculture water samples. The MAGIC method allows the investigation of phosphorus distributions and cycling for systems in which DIP is below the detection limits of conventional methods. Comparison between the two methods demonstrated that the concentrations obtained with both methods were significantly correlated. The differences of DIP and TDP concentrations measured with the two methods were higher when the concentrations of DIP and TDP were lower, implying the lower reproducibility at low concentrations. The concentration differences increase with the increase in the proportion of DOP in TDP, which indicates that the discrepancy of DIP concentrations measured with the two methods increases when the DOP concentration is high. The discrepancies indicated that the composition of P compounds differs depending on sample sources and water type; it would be useful to infer the presence of different phosphorus compound pools from differences between the two methods. This study indicates the potential presence of a pool of alkaline-labile compounds for samples from rainwater and rivers and estuaries surrounding the Jiaozhou Bay; the potential presence of acid-labile compounds that were adsorbed by Mg（OH）2 for samples from the Changjiang Estuary, Huanghai Sea, East China Sea, and groundwater; the potential presence of a substantial pool of acid-labile compounds that were not adsorbed by Mg（OH）2 for samples from the Huanghe Estuary, aquaculture water, the East China Sea algal bloom water, and the northern South China Sea.展开更多
基金The National Natural Science Foundation of China under contract Nos 40876054 and 40925017the Science and Technology Key Program of the Ministry of Education under contract Nos NCET-05-0593 and 108081the Special Funds from National Key Basic Research Program under contract Nos 2006CB400602 and 2007DFB20380
文摘Phosphorus （P） is an essential nutrient utilized by all organisms for energy transport and growth. Both the conventional molybdenum-blue method and the magnesium-induced coprecipitation （MAGIC） procedures were applied for the measurement of dissolved inorganic phosphorus （DIP） and total dissolved phosphorus （TDP） in more than 840 water samples collected between 2003 and 2005, including seawater （the Huanghai Sea, the East China Sea, and the northern South China Sea）, water from rivers and estuaries （the Changjiang, the Huanghe, and the major rivers emptying into the Jiaozhou Bay）, groundwater （in the drainage basin surrounding the Jiaozhou Bay）, rain-water, and aquaculture water samples. The MAGIC method allows the investigation of phosphorus distributions and cycling for systems in which DIP is below the detection limits of conventional methods. Comparison between the two methods demonstrated that the concentrations obtained with both methods were significantly correlated. The differences of DIP and TDP concentrations measured with the two methods were higher when the concentrations of DIP and TDP were lower, implying the lower reproducibility at low concentrations. The concentration differences increase with the increase in the proportion of DOP in TDP, which indicates that the discrepancy of DIP concentrations measured with the two methods increases when the DOP concentration is high. The discrepancies indicated that the composition of P compounds differs depending on sample sources and water type; it would be useful to infer the presence of different phosphorus compound pools from differences between the two methods. This study indicates the potential presence of a pool of alkaline-labile compounds for samples from rainwater and rivers and estuaries surrounding the Jiaozhou Bay; the potential presence of acid-labile compounds that were adsorbed by Mg（OH）2 for samples from the Changjiang Estuary, Huanghai Sea, East China Sea, and groundwater; the potential presence of a substantial pool of acid-labile compounds that were not adsorbed by Mg（OH）2 for samples from the Huanghe Estuary, aquaculture water, the East China Sea algal bloom water, and the northern South China Sea.
