It was demonstrated that there are seasonal changes of phosphate in the lakes, which was related to the eutrophication . In general, summer has higher level of phosphate whereas the winter has low phosphate. There are many reasons for such patterns. Recently, my work on the inorganic phosphatase from from iron oxides in the waters- contributed by the sediments might the the reasons. These inorganic phosphatase are sensitive to the temperature changes.
The details of my work can be found :
- Hydrolysis of Phosphate Esters Catalyzed by Inorganic Iron Oxide Nanoparticles Acting as Biocatalysts, Astrobiology 18(3) DOI: 10.1089/ast.2016.1628
- Hydrolysis of Glucose-6-phosphate in Aged, Acid-Forced Hydrolysed Nanomolar Inorganic Iron Solutions — An Inorganic Biocatalyst?2012, RSC Advances 2(1):199-208 DOI: 10.1039/C1RA00353D
In fact, it is a long history to use the iron salts to control the phosphate in the lakes. It was found that the effect was short , and the reasons for the short behaviors were considered as the decrease of iron sorption. Although some papers were demonstrate that the oxygen level, as well as the content of SO4 in the water might relate to the decrease of sorption capacity of iron in the sediment, but I think the main reasons were from these inorganic phosphatase, from the iron oxide nanoparticles in the water. The evidence of the total phosphorus and inorganic phosphate changes after the iron treatments in the lakes might be further indicate the contribution inorganic phosphatase . I would like to have more evidences to support my hypothesis ..Thanks
Dissolved inorganic phosphate (δ18OP), which distinguishes different phosphate sources:
Different isotopic techniques have been developed to measure oxygen isotope ratio of dissolved inorganic phosphate (δ18OP), which distinguishes different phosphate sources and also reflects the degree of phosphate turnover by organisms. Phosphorus (P), an essential element for all forms of life on earth, is also found in the environment and often limits the productivity of aquatic ecosystems. P in the environment can be organic and inorganic phosphates. Inorganic phosphate is essential for growth of microorganisms and often called orthophosphate. It has the formula PO43 −. It is also one of the ingredients in detergents, shampoo, toothpaste and other household products. On the other hand, organic phosphates are connected to a carbon compound. Phosphorus in soil is about 50% to 90% organic. Phosphorus that leached from agricultural land, domestic waste and industrial waste can cause eutrophication. Eutrophication is the phenomenon wherein algae and other microorganisms grow excessively in bodies of water. This algal bloom causes fish kill due to decrease in oxygen and production of toxic organisms. It has been noted that unlike seawater samples, dissolved inorganic phosphate in samples with high organic content such as river water is more rigorously extracted and isolated.
· A review on useful concepts for stable isotope of oxygen in phosphate (δ18Op) extraction, purification and analysis of freshwater samples and other potential phosphate sources
Abigail P. Cid-Andres* Microchemical Journal 123 (2015) 105-110
Thanks for Dr. Moussa input.
It is a key factor for us us to know what we have determined for phosphorus.
The classic and traditional method for orthophosphate by spectrophotometry are based on the formation of a stable phosphomolybdenum
blue complex, which allow the application of the Beer-Lambert Law in its simplest form. This procedure was first developed by Osmond in 1887 and Taylor & Miller
in 1914, but not widely utilized until introduction of catalysts
(antimony and others) to speed up the reaction three decades later by J. Murphy, J.P. Riley ( Anal. Chim. Acta 1962, 27: 31). It is noted that the acid in the reagent can significantly increase the hydrolysis of some organic phosphorus or the polyphosphate . The key of the reaction is the ratio of acid to Mo molar ratio. This is why we should reduce the acid concentration for the Murphy and Riley methods. I have modified the method for orthophosphate as well as the total dissolved organic phosphorus by persulfate . The details can be found as follows:
- Xiao-Lan Huang, Jia-Zhong Zhang: 2009, Neutral persulfate digestion at sub-boiling temperature in an oven for total dissolved phosphorus determination in natural waters. Talanta 78(3): 1129-1135 DOI:10.1016/j.talanta.2009.01.029
- Huang Xiao-Lan, Jia-Zhong Zhang, 2006, Surfactant-Sensitized Malachite Green Method for Trace Determination of Orthophosphate in Aqueous Solutions, Analytical Chimica Acta 580:55-67. doi:10. 1016/ j.aca. 2006.07.046
- Huang Xiao-Lan, Jia-Zhong Zhang, 2008, Kinetic Spectrophotometric Determination of Submicromolar Orthophosphate by Molybdate Reduction, Microchemical Journal, 89:58-71. doi:10.1016/j.microc. 20007.12.001.
- Zhang JZ, Fischer CJ, Ortner PB. 1999, Optimization of performance and minimization of silicate interference in continuous flow phosphate analysis. Talanta. 1999 Jun 14;49(2):293-304
This method is intended to determine the stable isotope content of the oxygen of the phosphate group in order to know the origin of the latter. (P in the environment can be organic and inorganic phosphates) .. the objective is not the dosage of the concentration of phosphoric acid. it is not a classic and traditional method for orthophosphate by spectrophotometry
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