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.

Soluble nitrogen and phosphorus excretion of exotic freshwater mussels (Dreissena spp.): potential impacts for nutrient remineralisation in western Lake Erie

Abstract: SUMMARY 1. Recent increases in phytoplankton biomass and the recurrence of cyanobacterial blooms in western Lake Erie, concomitant with a shift from a community dominated by zebra mussels (Dreissena polymorpha) to one dominated by quagga mussels (D. bugensis), led us to test for differences in ammonia-nitrogen and phosphate-phosphorus excretion rates of these two species of invasive molluscs. 2. We found significant differences in excretion rate both between size classes within a taxon and between taxa, with zebra mussels generally having greater nutrient excretion rates than quagga mussels. Combining measured excretion rates with measurements of mussel soft-tissue dry weight and shell length, we developed nutrient excretion equations allowing estimation of nutrient excretion by dreissenids. 3. Comparing dreissenid ammonia and phosphate excretion with that of the crustacean zooplankton, we demonstrated that the mussels add to nitrogen and phosphorus remineralisation, shortening nitrogen and phosphorus turnover times, and, importantly, modify the nitrogen and phosphorus cycles in Lake Erie. The increased nutrient flux from dreissenids may facilitate phytoplankton growth and cyanobacterial blooms in well-mixed and/or shallow areas of western Lake Erie.

Dietary 1,25-dihydroxycholecalciferol supplementation increases natural phytate phosphorus utilization in chickens.

Abstract: These studies were conducted to determine if supplementation of a corn-soybean meal diet with 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] would increase the utilization of natural phytate phosphorus by broiler chickens. Two experiments were conducted to evaluate the effect of dietary 1,25-(OH)2D3 in the presence and absence of supplemental phytase and at several dietary levels of inorganic phosphorus supplementation. The criteria measured in these studies were weight gain, gain:feed ratio, bone ash, rickets due to phosphorus deficiency, plasma calcium and phosphorus and retention of calcium, phosphorus and phytate phosphorus. In the first experiment, the types and amounts of fecal inositol phosphates were determined by HPLC, and the total fecal phytate was determined by the classic FeCl3 precipitation technique. In the first experiment, the addition of 1,25-(OH)2D3 to the diet in the presence of dietary phytase resulted in greater 9-d weight and bone ash and lower incidence of rickets; the retention of total fecal phytate and phytate phosphorus was greater than in controls. The second experiment was a complete 2 x 2 x 2 factorial design [phosphorus levels x phytase x 1,25-(OH)2D3]. The addition of 1,25-(OH)2D3 alone to the diet resulted in greater 9-d weight and bone ash, lower incidence of rickets, and greater retention of total calcium and phosphorus and phytate phosphorus. The highest retention of phytate phosphorus (79.4%) was obtained when both phytase and 1,25-(OH)2D3 were present in the diet. The possible mode of action and importance of these results in many areas of nutrition and environmental science are discussed.

Nutrient uptake by leaves and roots of the seagrass Thalassia hemprichii in the Spermonde Archipelago, Indonesia

Abstract: The kinetics of ammonium and phosphate uptake by leaves and roots of the tropical seagrass Thalassia hemprichii were investigated in laboratory experiments. Uptake in leaves of plants from 3 different locations, covering the range from coastal to oceanic conditions in the region of investigation (Spermonde Archipelago, South Sulawesi, Indonesia), was compared. The leaves from all plant samples showed a clear capacity for both ammonium and phosphate uptake. This uptake could be described by Michaelis-Menten kinetics. v(max) ranged between 32 and 37 mu mol g(-1) leaf dry weight h(-1) for ammonium and between 2.2 and 3.2 mu mol g(-1) leaf dry weight h(-1) for phosphate. K-m ranged between 21 and 60 mu M for ammonium and between 7.7 and 15 mu M for phosphate. There was no significant site difference in uptake characteristics (v(max) and K-m) of ammonium and phosphate. Uptake of ammonium and phosphate by roots was investigated with plants from the intermediate location, Barang Lompo, using an approach which allowed only calculation of uptake rates at natural pore water concentrations. Uptake rates were 22 and 1.0 mu mol g(-1) root dry weight h(-1) for ammonium and phosphate, respectively Calculations suggest that at all 3 locations uptake of ammonium and phosphate by roots was probably limited by the diffusion of nutrients in the sediment rather than by their uptake capacity. Evidence was found that the availability of nutrients in the root zone relative to the leaf zone affects the uptake affinity of the leaves. The role of roots versus leaves in supplying plant nutrients is discussed. We concluded that even in the tropics, where water column nutrient concentrations are often very low, leaves clearly have a significant ability for ammonium or phosphate uptake and that in some situations nutrient uptake by the leaves may even be essential in meeting plant nutrient demands. [KEYWORDS: ammonium; phosphate; nutrient uptake kinetics; leaves; roots; seagrass; Thalassia hemprichii; Indonesia Zostera-marina-l; south sulawesi indonesia; phosphorus; epiphytes; release; phosphate; kinetics; biomass; nitrate; ammonia]