Showing papers on "Phosphorus published in 2008"

Eutrophication of lakes cannot be controlled by reducing nitrogen input: Results of a 37-year whole-ecosystem experiment

Abstract: Lake 227, a small lake in the Precambrian Shield at the Experimental Lakes Area (ELA), has been fertilized for 37 years with constant annual inputs of phosphorus and decreasing inputs of nitrogen to test the theory that controlling nitrogen inputs can control eutrophication. For the final 16 years (1990-2005), the lake was fertilized with phosphorus alone. Reducing nitrogen inputs increasingly favored nitrogen-fixing cyanobacteria as a response by the phytoplankton community to extreme seasonal nitrogen limitation. Nitrogen fixation was sufficient to allow biomass to continue to be produced in proportion to phosphorus, and the lake remained highly eutrophic, despite showing indications of extreme nitrogen limitation seasonally. To reduce eutrophication, the focus of management must be on decreasing inputs of phosphorus.

Global distribution of atmospheric phosphorus sources, concentrations and deposition rates, and anthropogenic impacts

Abstract: A worldwide compilation of atmospheric total phosphorus (TP) and phosphate (PO4) concentration and deposition flux observations are combined with transport model simulations to derive the global distribution of concentrations and deposition fluxes of TP and PO4. Our results suggest that mineral aerosols are the dominant source of TP on a global scale (82%), with primary biogenic particles (12%) and combustion sources (5%) important in nondusty regions. Globally averaged anthropogenic inputs are estimated to be similar to 5 and 15% for TP and PO4, respectively, and may contribute as much as 50% to the deposition over the oligotrophic ocean where productivity may be phosphorus-limited. There is a net loss of TP from many (but not all) land ecosystems and a net gain of TP by the oceans (560 Gg P a(-1)). More measurements of atmospheric TP and PO4 will assist in reducing uncertainties in our understanding of the role that atmospheric phosphorus may play in global biogeochemistry.

Efficiency of soil and fertilizer phosphorus use. Reconciling changing concepts of soil phosphorus behaviour with agronomic information

Abstract: Efficiency of soil and fertilizer phosphorus use: reconciling changing concepts of soil phosphorus behaviour with agronomic information , Efficiency of soil and fertilizer phosphorus use: reconciling changing concepts of soil phosphorus b... , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Control of Lacustrine Phytoplankton by Nutrients: Erosion of the Phosphorus Paradigm

Abstract: Control of lacustrine phytoplankton biomass by phosphorus is one of the oldest and most stable paradigms in modern limnology. Even so, evidence from bioassays conducted by multiple investigators at numerous sites over the last three decades shows that N is at least as likely as P to be limiting to phytoplankton growth. A number of important flaws in the evidence supporting the phosphorus paradigm have contributed to an unrealistic degree of focus on phosphorus as a controlling element. These include insufficient skeptism in interpretation of: 1) the phosphorus: chlorophyll correlation in lakes, 2) the results of whole-lake fertilization experiments, and 3) stoichiometric arguments based on total N:total P ratios for inland waters. A new paradigm based on parity between N and P control of phytoplankton biomass in lakes seems more viable than the P paradigm. The new paradigm renews interest in the degree to which plankton communities are molded in composition by small differences in relative availability of N and P, the mechanisms that lead to a high frequency of N limitation in oligotrophic lakes, and the failure of aquatic N-fixers to compensate significantly for N deficiency under most conditions. A new N/P paradigm still must acknowledge that suppression of P loading often will be the most effective means of reducing phytoplankton biomass in eutrophic lakes, even if N is initially limiting. From error to error one discovers the entire truth Sigmund Freud (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Global phosphorus flows and environmental impacts from a consumption perspective

Abstract: Human activities have significantly intensified natural phosphorus cycles, which has resulted in some serious environmental problems that modern societies face today. This article attempts to quantify the global phosphorus flows associated with present day mining, farming, animal feeding, and household consumption. Various physical characteristics of the related phosphorus fluxes as well as their environmental impacts in different economies, including the United States, European countries, and China, are examined. Particular attention is given to the global phosphorus budget in cropland and the movement and transformation of phosphorus in soil, because these phosphorus flows, in association with the farming sector, constitute major fluxes that dominate the anthropogenic phosphorus cycle. The results show that the global input of phosphorus to cropland, in both inorganic and organic forms from various sources, cannot compensate for the removal in harvests and in the losses by erosion and runoff. A net loss of phosphorus from the world's cropland is estimated at about 10.5 million metric tons (MMT) phosphorus each year, nearly one half of the phosphorus extracted yearly.

Resource partitioning for soil phosphorus: a hypothesis

Abstract: Summary 1. Organic phosphorus is abundant in soil and its turnover can supply a considerable fraction of the phosphorus taken up by natural vegetation. Despite this, the ecological significance of organic phosphorus remains poorly understood, which is remarkable given the biological importance of phosphorus in terrestrial environments. 2. Of particular interest is the possibility that coexisting plant species partition soil organic phosphorus to reduce competition. This seems likely given the large number of biologically available phosphorus compounds that occur in soil and the variety of mechanisms by which plants can utilize them. 3. Here I propose a conceptual model of resource partitioning for soil phosphorus. The model describes a hypothetical example of four coexisting plant species that differ in their ability to access soil organic phosphorus compounds, which are grouped to form a gradient of biological availability based on the processes involved in their utilization by plants. 4. Synthesis: Resource partitioning for soil phosphorus could provide an additional mechanism to

Factors Influencing Luxury Uptake of Phosphorus by Microalgae in Waste Stabilization Ponds

Abstract: Phosphorus removal in waste stabilization ponds (WSP) is highly variable, but the reasons for this are not well understood. Luxury uptake of phosphorus by microalgae has been studied in natural systems such as lakes but not under the conditions found in WSP. This work reports on the effects of phosphate concentration, light intensity, and temperature on luxury uptake of phosphorus by WSP microalgae in continuous culture bioreactors. Increasing temperature had a statistically significant "positive effect" on intracellular acid-insoluble polyphosphate concentration. It is likely that elevated temperature increased the rate of polyphosphate accumulation, but because the biomass was not starved of phosphate, the stored acid-insoluble polyphosphate was not utilized. Increasing light intensity had no effect on acid-insoluble polyphosphate but had a "negative effect" on the acid-soluble polyphosphate. A possible explanation for this is that the faster growth rate at high light intensity results in this form of polyphosphate being utilized by the cells for synthesis of cellular constituents at a rate that exceeds replenishment. The variability in the phosphorus content of the microalgal biomass shows that with this new understanding ofthe luxury uptake mechanism there is the potential to optimize WSP for biological phosphorus removal.

Simultaneous nitrification, denitrification, and phosphorus removal from nutrient‐rich industrial wastewater using granular sludge

Abstract: The biological removal of nitrogen and phosphorus from nutrient-rich abattoir wastewater using granular sludge has been investigated. A lab-scale sequencing batch reactor, seeded with granular sludge developed using synthetic wastewater, was operated for 13 months under alternating anaerobic and aerobic conditions. It is demonstrated that the granules could be sustained and indeed further developed with the use of abattoir wastewater. The organic, nitrogen, and phosphorus loading rates applied were 2.7 gCOD L-1 day-1, 0.43 gN L-1 day-1, and 0.06 gP L-1 day-1, respectively. The removal efficiency of soluble COD, soluble nitrogen and soluble phosphorus were 85%, 93%, and 89%, respectively. However, the high suspended solids in the effluent limited the overall removal efficiency to 68%, 86%, and 74% for total COD, TN, and TP, respectively. This good nutrient removal was achieved through the process known as simultaneous nitrification, denitrification, and phosphorus removal, likely facilitated by the presence of large anoxic zones in the center of the granules. The removal of nitrogen was likely via nitrite optimizing the use of the limited COD available in the wastewater. Accumulibacter spp. were found to be responsible for most of the denitrification, further reducing the COD requirement for nitrogen and phosphorus removal. Mineral precipitation was evaluated and was not found to significantly contribute to the overall nutrient removal. It is also shown that the minimum HRT in a granular sludge system is not governed by the sludge settleability, as is the case with floccular sludge systems, but likely by the limitations associated with the transfer of substrates in granules. Biotechnol. Bioeng. 2008;100: 529-541. © 2007 Wiley Periodicals, Inc.

The Ecophysiology of Plant-Phosphorus Interactions

Abstract: Contributors.- Preface.- 1. Phosphorus in the global environment H. Tiessen.- 2. Carbon/nitrogen/phosphorus allometric relations across species K.J. Niklas.- 3. Phosphorus and aquatic plants G. Thiebaut.- 4. Phosphorus nutrition of terrestrial plants P.J. White, J.P. Hammond.- 5. Root strategies for phosphorus acquisition J.P. Lynch, K.M. Brown.- 6. Plants without arbuscular mycorrhizae C.P. Vance.- 7. Mycorrhizal symbiosis J.M. Barea Navarro et al.- 8. The role of rhizosphere microorganisms in relation to P uptake by plants P. Marschner.- 9. Soil and fertilizer phosphorus in relation to crop nutrition E.A. Kirkby, A.E. (Johnny) Johnston.- 10. Diagnosing phosphorus deficiency in crop plants J.P. Hammond, P.J. White.- 11. Potential and limitations to improving crops for enhanced phosphorus utilization T.S. George, A.E. Richardson.- 12. Phosphorus and the future J.A. Raven.- Index.-

Rethinking early Earth phosphorus geochemistry

Abstract: Phosphorus is a key biologic element, and a prebiotic pathway leading to its incorporation into biomolecules has been difficult to ascertain. Most potentially prebiotic phosphorylation reactions have relied on orthophosphate as the source of phosphorus. It is suggested here that the geochemistry of phosphorus on the early Earth was instead controlled by reduced oxidation state phosphorus compounds such as phosphite (HPO32−), which are more soluble and reactive than orthophosphates. This reduced oxidation state phosphorus originated from extraterrestrial material that fell during the heavy bombardment period or was produced during impacts, and persisted in the mildly reducing atmosphere. This alternate view of early Earth phosphorus geochemistry provides an unexplored route to the formation of pertinent prebiotic phosphorus compounds, suggests a facile reaction pathway to condensed phosphates, and is consistent with the biochemical usage of reduced oxidation state phosphorus compounds in life today. Possible studies are suggested that may detect reduced oxidation state phosphorus compounds in ancient Archean rocks.

Changes in phosphorus biogeochemistry along an estuarine salinity gradient: The iron conveyer belt

Abstract: We used sequential extractions to quantify different forms of particulate phosphorus (PP) in sediments along the salinity gradient of the Patuxent River estuary. About 50–90% of the PP was phosphate bound to iron oxides (Fe-P), and 8–30% was organic P (org-P). Loosely sorbed phosphate (sorb-P), detrital apatite, and authigenic plus biogenic apatite each made up ,10% of the PP. Suspended sediments from the watershed and deposited sediments in tidal freshwater had the highest concentrations of Fe-P, ranging about 30–55 mmol g21 sediment. As pore-water salinity increased to 7 along the estuarine gradient, Fe-P declined to 15–25 mmol g21, org-P increased from 4 to 10 mmol g21, sorb-P increased from 0.5 to 2.5 mmol g21, and total sediment PP declined from 60 to 40 mmol g21. Concentrations of pore-water solutes also changed with salinity. As salinity increased, dissolved Fe and ammonium decreased, while dissolved phosphate increased. Near the freshwater end of the gradient, the molar ratio of pore-water ammonium : phosphate was generally .16 (the Redfield ratio) and ranged up to .700, while at the saline end of the gradient the ratio was generally ,16 and ranged down to ,1.5. Our observations are consistent with the hypothesis that phosphate is released from terrigenous sediments when they are deposited in saline portions of the estuary where sulfide may enhance dissolution of Fe-P and form Fe sulfide precipitates. Such phosphate release may contribute to the generally observed switch from phosphorus limitation in freshwater to nitrogen limitation in coastal marine water.

Phosphorus in groundwater – an overlooked contributor to eutrophication?

Abstract: This paper presents the first international assessment of phosphorus concentrations in groundwater, using data from the Republic of Ireland, Northern Ireland, Scotland, England and Wales. Phosphorus is considered to be the main limiting nutrient in most freshwater ecosystems. Controlling phosphorus inputs is thus considered the key to reducing eutrophication and managing ecological quality. Very little attention has been paid to evaluating transfers via groundwater due to the long-held belief that adsorption and metal complex formation retain the majority of potentially mobile phosphorus. In each country, ecologically-important phosphorus thresholds are exceeded in a significant number of groundwater samples. The relative contributions of potential sources for these elevated concentrations are currently unclear but there is evidence to suggest that they are at least partly anthropogenic. The results suggest that groundwater P concentrations are such that they may be a more important contributor to surface water phosphorus than previously thought. Copyright © 2008 John Wiley & Sons, Ltd.

Exopolysaccharide : a novel important factor in the microbial dissolution of tricalcium phosphate

Abstract: Four strains (Enterobacter sp. EnHy-401, Arthrobacter sp.ArHy-505, Azotobacter sp.AzHy-510 and Enterobacter sp.EnHy-402) which have the ability to solubilize tricalcium phosphate (TCP) were used to study the mechanism of P-solubilization. It was found that three phosphate solubilizing bacteria (EnHy-401, ArHy-505 and AzHy-510) producing exopolysaccharide (EPS) have a stronger ability for P-solubilization than isolate EnHy-402 without EPS production, of those, the strain EnHy-401 with the highest EPS production and efficient organic acids on P-solubilization had a stronger capacity for P-solubilization than the others. Further studies demonstrated that addition of EPS into medium could increase the amount of phosphorus solubilized by organic acid, but failed to release phosphorus from TCP alone. The synergistic effects of EPS and organic acid on TCP solubilization varied with the origin and the concentration of EPS in medium. EPS produced by EnHy-401 was most effective in promoting phosphorus release at an optimal concentration in medium. The increase of P-solubilization brought by EPS attributed to the participation of EPS led to the change in homeostasis of P-solubilization, pushing it towards P dissolved by holding free phosphorus in the medium, consequently resulting in greater phosphorus released from insoluble phosphate. We therefore suggest that EPS with ability of phosphorus-holding may be a novel important factor in the microbial dissolution of TCP except for organic acid.

Phosphorus Removal and Recovery from Municipal Wastewaters

Abstract: Phosphorus is a key pollutant in municipal wastewater. To minimise eutrophication, treatment facilities must often reduce phosphorus levels to less than 1 mg L -1 . Two main approaches to achieving this are chemical precipitation and enhanced biological uptake. Chemical precipitation is widely used and relatively simple; biological phosphorus removal is more complex but relies less on the addition of chemicals and also offers the opportunity to reuse the phosphorus. Phosphorus can be released from cells and converted to calcium phosphate or the mineral struvite. While the products have been shown to be excellent fertilisers, the economic drivers for recovery are still not clear.

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.

Phosphate Mineral Reactivity and Global Sustainability

Abstract: Phosphorus is a unique element. It is the limiting nutrient controlling biological productivity in many terrestrial and marine environments. When in excess, however, dissolved phosphate leads to uncontrollable biological growth and water-quality problems through a process called eutrophication. The use of phosphate minerals and their products as fertilizers has increased tremendously global food production; it would not be possible to feed the current world population without phosphate fertilizers. Yet phosphate is a limited global resource; current estimates suggest economic phosphorus supply may be severely depleted over the next 100 years. Nevertheless, mineralogists and geochemists have invested little time investigating phosphate mineral stability, reactivity, and transformations. This issue attempts to bring phosphates to the forefront of our scientific endeavours.