Phosphorus

About: Phosphorus is a research topic. Over the lifetime, 53120 publications have been published within this topic receiving 939731 citations. The topic is also known as: element 15 & P.

Secreted acid phosphatase is expressed in cluster roots of lupin in response to phosphorus deficiency

Abstract: The roots of white lupin (Lupinus albus L. cv. Kievskij mutant) secrete acid phosphatase, S-APase, when they grow under conditions of low available phosphorus (P). S-APases hydrolyze organic phosphate compounds in the rhizosphere and supply inorganic phosphate to the plants. Low phosphorus availability also induces vigorous growth of cluster roots. In this study, the function of cluster roots was investigated with reference to S-APase secretion. White lupins were grown in hydroponic culture in a greenhouse under P-deficient and P-sufficient conditions. S-APase in the excised roots after treatment was detected by staining with 4-methylumbelliferone phosphate (MUP). Gene expression of S-APase in cluster and normal roots was also investigated. Activity was greatest in the roots of plants grown under conditions of P -deficiency, particularly in cluster roots. S-APase gene expression was induced by a decrease in internal P concentrations, and was especially high in cluster roots formed under conditions of P -deficiency. It was suggested that decrease of internal P concentration stimulated both of the S-APase expression and cluster root formation.

Beneath the Salt Marsh Canopy: Loss of Soil Strength with Increasing Nutrient Loads

Abstract: Although the broadly observed increase in nutrient loading rates to coastal waters in the last 100 years may increase aboveground biomass, it also tends to increase soil metabolism and lower root and rhizome biomass—responses that can compromise soil strength. Fourteen different multiyear field combinations of nutrient amendments to salt marshes were made to determine the relationship between soil strength and various nitrogen, phosphorus, and nitrogen+phosphorus loadings. There was a proportional decline in soil strength that reached 35% in the 60- to 100-cm soil layer at the highest loadings and did not level off. These loading rates are equivalent to those in the flow path of the Caernarvon river diversion, a major wetland restoration project near New Orleans; 12% of the wetlands in the flow path were converted to open water in 2005. The increased nutrient loading from the Mississippi River watershed this century has also driven the formation of the low oxygen zone (the "Dead Zone") that forms off the Louisiana-Texas shelf each summer. These results suggest that improving water quality in the watershed will aid the restoration of both offshore waters and coastal wetland ecosystems.

Phosphate removal from wastewater by model-La(III) zeolite adsorbents.

Abstract: Phosphorus is one of the primary nutrients which leads to eutrophication and accelerates aging process in enclosed water bodies. Because of the poor phosphorus selectivity of other adsorbents, the novel La(III)-modified zeolite adsorbent (LZA) was prepared by modifying 90 nm zeolite with lanthanide to selectively remove phosphate in the presence of various omnipresent anions, such as sulfates, bicarbonates, and chlorides. Through batch and fixed bed operation, the following optimum conditions were obtained: concentration of lanthanum chloride solution 0.05 mol/L; solid/liquor ratio 1/25; pH 10; calcination temperature 550°C; time 1 h. The value of the Freundlich model constants Kf and 1/n were found to be 16.76 mg/L and 0.2209, respectively. In addition, when calculated at pH 6.0, distribution coefficient KD could be as high as 36.6. Furthermore, in the alkaline pH range, solution of 0.8 mol/L NaCl was used to regenerate the saturated LZA, which could reach the high regeneration efficiency as high as 100%. Because of the good selectivity and regenerability of LZA, it might serve as a potential way for advanced phosphate removal from the sewage containing other anions.