Phosphate Pollution Research Articles

Загрязнение фосфатами вод реки Сусуя на юге Сахалина

The article explores the problem of organic compounds polluting natural watercurrents (on the example of Susuja waters phosphate pollution).

Effect of probiotics on alkaline phosphatase activity and nutrient level in sediment of shrimp, Penaeus vannamei, ponds

The effect of probiotics on alkaline phosphatase activity (APA) and nutrient concentrations (total phosphorus, (TP); total inorganic phosphorus, (TIP); total organic phosphorus, (TOP); total organic carbon (TOC) and total nitrogen (TN)) in sediment of shrimp, Penaeus vannamei, cultural pond was investigated. Three ponds were treated with commercial probiotics and three were used as the control (without any probiotics). TP was significantly lower ( P < 0.05) in the treatment group compared with the control group at 20, 40 and 60 days post treatment. However, the difference of TP content was reduced to less significant after 80 days. The TIP concentrations of the treatment in sediment was lower ( P < 0.05) than that of the control on day 20, 40 and 80. No significant difference ( P > 0.05) was found in TOP content. The amount of total N and TOC contents at day 0 of the experiment were not significantly between treatment and control ponds ( P > 0.05). However, the probiotic supplementation remarkably decreased TN and TOC ( P < 0.05) in the treatment group after day 20. APA was no significant difference ( P > 0.05) between treatment and the control groups. The seasonal APA followed a similar trend for all the ponds, low at the beginning, peaked on day 20, and then showed a second peak on day 100. The data showed that the application of probiotics would mitigate the nitrogen and phosphate pollution in ponds sediments.

Production of renewable bioproducts and reduction of phosphate pollution through the lime pretreatment and acidogenic digestion of dairy manure

Acidogenic digestion with lime pretreatment was proposed as a means of reducing soluble reactive phosphorous concentrations in dairy cow manure while producing calcium carboxylate salts as a chemical platform for production of fuels and chemicals via the MixAlco Process. When concentrated in small geographic areas, large dairy operations can have environmentally harmful impacts on their watersheds, due to excess nutrients causing eutrophication of local water bodies. In Central Texas, as in many other areas, phosphorous contamination from confined animal feeding operations is a leading cause of human induced eutrophication. It was found that lime pretreatment followed by acidogenic or methanogenic anaerobic digestion led to substantial reductions in soluble reactive phosphate (SRP) levels while also producing potentially valuable products. Dairy manure filtrate was analyzed for SRP before and after the process steps of lime pretreatment and anaerobic digestion. An average reduction of SRP by 89% was observed through the two step process for lime pretreatment coupled with acidogenic digestion. Acidogenic digestion was demonstrated to produce mixed organic acids at mesophillic temperatures and primarily acetic acid at thermophillic temperatures. Using the MixAlco Process, the carboxylate salts of these organic acids could potentially be converted into marketable fuels and chemicals. © 2008 American Institute of Chemical Engineers Environ Prog, 2009

Heavy Metals Pollution of the Atlantic Marine Environment by the Moroccan Phosphate Industry, as Observed through their Bioaccumulation in Ulva Lactuca

The Moroccan phosphate industry releases large amounts of heavy metals in the Atlantic Ocean in the surroundings of two places: Safi and Jorf Lasfar. The major waste, called phosphogypsum and composed of calcium sulphate and other additional salts, is introduced into sea water in particulate form. After dissolution of the particles, heavy metal concentrations can be influenced near the release point. Two multi-element analytical techniques were used to measure 47 element concentrations in various materials involved in the study of the phosphate pollution: Inductively Coupled Plasma Mass Spectrometry (ICPMS) and instrumental neutron activation analysis (INAA). At first, phosphate and phosphogypsum were characterized in order to recognize the overall features of the heavy metal pollution source. From the yearly amount of phosphogypsum produced by the Moroccan industry and the element concentrations in phosphogypsum, it has been possible to estimate a yearly flux of heavy metals introduced in the Atlantic Ocean. Algae were used as bio-accumulator materials of heavy metals in the marine environment, in the region of Jorf Lasfar, in order to significantly reveal the signal of the heavy metal pollution. Ulva lactuca Linnaeus was selected to assess heavy metal pollution around the waste release point. Accumulation factors were determined for 47 elements in U. lactuca, by comparing mean concentrations obtained in algae collected in non-polluted sites (background sites) and an average sea water concentration given in the literature. The ratio between the concentration in U. lactuca, collected in a polluted site to the background concentration in U. lactuca, was determined, giving an estimate of the pollution factor for the same elements by the phosphate industry. The decrease of the pollution due to the dilution in the sea water was observed as far as 6 km southward of the release point. A specific variation was observed for lead and its isotopic composition, denoting that the phosphate industry is not the only pollution source in this region. Natural processes were likely involved to induce the lead concentrations variations along the littoral.

Comparison of Selected Physicochemical Characteristics of Commercial Phytases Relevant to their Application in Phosphate Pollution Abatement

The enzyme phytase catalyses the dephosphorylation of phytic acid and it's salts, phytates. Supplementation of monogastric animal feed with microbial-derived phytase increases the bioavailability of phytic acid bound phosphate. This facilitates a reduction in the addition of inorganic phosphate to the feed and reduces phosphorus excretion. To achieve maximum efficacy in terms of phosphate pollution abatement, supplemental phytases added to animal feed must survive thermal processing of the feed, resist inactivation by the proteolytic enzymes encountered in the animal's digestive tract and display high activity at physiological temperature and pH. A series of in vitro experiments were carried out to determine the relative suitability of four major commercial phytase products for use in animal feed. The enzymes assessed lost between 14% and 72% of their original activities after heating to 80°C for 5 minutes. After exposure to simulated upper digestive tract conditions, the phytases assessed retained between 0 and 28% of their original activities. The commercial phytases displayed between 98% and 67% of their maximum activities at 39°C and all phytases assessed had an optimum pH between pH 4 and pH 5. None of the phytases assessed satisfied all of the criteria of an ideal phytase for use in animal feed.

Biochemical properties and substrate specificities of alkaline and histidine acid phytases

Phytases are a special class of phosphatase that catalyze the sequential hydrolysis of phytate to less-phosphorylated myo-inositol derivatives and inorganic phosphate. Phytases are added to animal feedstuff to reduce phosphate pollution in the environment, since monogastric animals such as pigs, poultry, and fish are unable to metabolize phytate. Based on biochemical properties and amino acid sequence alignment, phytases can be categorized into two major classes, the histidine acid phytases and the alkaline phytases. The histidine acid phosphatase class shows broad substrate specificity and hydrolyzes metal-free phytate at the acidic pH range and produces myo-inositol monophosphate as the final product. In contrast, the alkaline phytase class exhibits strict substrate specificity for the calcium-phytate complex and produces myo-inositol trisphosphate as the final product. This review describes recent findings that present novel viewpoints concerning the molecular basis of phytase classification.

Estimation of soil phosphate adsorption capacity by means of a pedotransfer function

The capacity of soil to protect the aquatic environment against pollution is an important soil function. Thus, the phosphate adsorption capacity (PAC) is important in predicting the risk of phosphate pollution of the aquatic environment because of overfertilisation and because of reestablishment of former drained and cultivated wetlands. Moreover, PAC is an essential property in assessing the risk of drain and ground water contamination with the widely used glyphosate herbicide, which may compete with phosphate for adsorption sites on soil solids. As aluminium and iron oxides are the main phosphate adsorbents in many soils, PAC can be predicted by pedotransfer functions based on various aluminium and iron oxide fractions such as oxalate-extractable aluminium and iron (Al o, Fe o) and dithionite-extractable iron (Fe d). Accordingly, experimentally determined PAC taken as the sum of oxalate-extractable phosphate and the Langmuir maximum of the phosphate adsorption isotherm was found to be well predicted by the pedotransfer function P calc=0.22×Al o+0.12×Fe o+0.02×(Fe d−Fe o) for a wide range of noncalcareous soils including Alfisols, Entisols, Inceptisols, Oxisols, Spodosols, and Ultisols from various parts of the world. A set of noncalcareous soil samples from Denmark, Ghana, and Tanzania was used in developing this pedotransfer function, while another set of soils from Canada and Tanzania was used in testing the function. While close relationships between experimentally determined and predicted PACs were obtained with these soils, the function failed, however, to predict PAC of two Tanzanian Andisols.

Effects of inorganic and organic phosphate exposure on aspects of reproduction in the common sea urchin Lytechinus variegatus (Echinodermata: Echinoidea).

The common nearshore sea urchin Lytechinus variegatus is capable of surviving exposure to inorganic phosphate concentrations as high as 3.2 mg/l(-1) and organic phosphate concentrations of 1,000 mg/l(-1). However, chronic exposure to low, medium, or high sublethal concentrations of these phosphates inhibits gonadal tissue indices and spawning activity while altering biochemical composition of gonads, reducing size frequencies of oocyte diameters, and changing gonadal volume fractions. Gonad indices declined significantly in individuals maintained in all phosphate concentrations after both one- and two-month exposures, while percentages of ripe individuals (oozing gametes upon dissection) were reduced after a two-month exposure in individuals maintained in medium and high organic phosphate concentrations. Levels of carbohydrates and lipids were lower in gonads of individuals maintained in all concentrations of both phosphates. Size frequency distributions of oocyte diameters revealed a dramatic decrease in oocyte size with increasing concentrations of both phosphates. Gonadal volume fractions of developing male and female gametes decreased with exposure to increasing phosphate levels. Volume fractions of nutritive phagocytes declined in testes of individuals held in the highest concentration of organic phosphate but displayed no significant change in ovaries. Volume fractions of mature gametes also decreased in gonads of individuals exposed to increasing concentrations of inorganic phosphate, but they remained constant in individuals exposed to all concentrations of organic phosphate. These findings indicate that shallow-water populations of L. variegatus subjected to inorganic and organic phosphate pollutants will exhibit stress that may impair reproductive output, gametogenesis, and spawning in the natural environment.

The impact of phosphate loading activities on near marine environment: the Syrian coast

The impact of loading cargoes of phosphate ore into ships on the near marine environment at the Syrian coast has been evaluated. Results have shown a significant enhancement of 210Po, 210Pb and other natural radionuclides in sediment and surface water inside the port area. The highest 210Po and 210Pb concentrations observed in sediment were found to be 170 and 64 Bq kg −1, respectively, while 210Pb and 210Po concentrations in surface water ranged from 5 to 20 mBq l −1 and 0.93 to 3.23 mBq l −1. In addition, comparable values of 210Po and 210Pb for all marine organisms (algae, crab and fish) suggest that their use as indicators for phosphate pollution is not recommended. However, the effect of loading cargoes on the port-marine environment of Tartous was found to be mainly related to wind direction where radioactive air particulate are either being dispersed to land or sea.

Enzyme Mechanism and Catalytic Property of β Propeller Phytase

Background: Phytases hydrolyze phytic acid ( myo-inositol-hexakisphosphate) to less-phosphorylated myo-inositol derivatives and inorganic phosphate. Phytases are used in animal feed to reduce phosphate pollution in the environment. Recently, a thermostable, calcium-dependent Bacillus phytase was identified that represents the first example of the β propeller fold exhibiting phosphatase activity. We sought to delineate the catalytic mechanism and property of this enzyme. Results: The crystal structure of the enzyme in complex with inorganic phosphate reveals that two phosphates and four calcium ions are tightly bound at the active site. Mutation of the residues involved in the calcium chelation results in severe defects in the enzyme's activity. One phosphate ion, chelating all of the four calcium ions, is close to a water molecule bridging two of the bound calcium ions. Fluoride ion, which is expected to replace this water molecule, is an uncompetitive inhibitor of the enzyme. The enzyme is able to hydrolyze any of the six phosphate groups of phytate. Conclusions: The enzyme reaction is likely to proceed through a direct attack of the metal-bridging water molecule on the phosphorous atom of a substrate and the subsequent stabilization of the pentavalent transition state by the bound calcium ions. The enzyme has two phosphate binding sites, the “cleavage site”, which is responsible for the hydrolysis of a substrate, and the “affinity site”, which increases the binding affinity for substrates containing adjacent phosphate groups. The existence of the two nonequivalent phosphate binding sites explains the puzzling formation of the alternately dephosphorylated myo-inositol triphosphates from phytate and the hydrolysis of myo-inositol monophosphates.

The effects of organic and inorganic phosphates on fertilization and early development in the sea urchin Lytechinusvariegatus (Echinodermata: Echinoidea)

The embryos of the sea urchin Lytechinus variegatus are capable of surviving chronic exposure to inorganic sodium phosphate and organic triethyl phosphate concentrations as high as 6 and 1000 mg l −1 seawater, respectively. However, chronic exposure to sub-lethal concentrations of these phosphates may cause arrested or abnormal embryonic development. We measured fertilization success and percentages of normal, arrested and abnormal embryos exposed to low, medium and high sub-lethal concentrations of inorganic and organic phosphate. Fertilization success was significantly reduced in all phosphate treatments. After attaining the 4-cell stage, embryos exposed to the highest phosphate concentrations displayed arrested development. Percentages of abnormally developing embryos showed a strong concentration dose–response with a significant increase in abnormal embryonic development with increasing phosphate concentration. Overall, these results indicate that the gametes and embryos of L. variegatus may provide a rapid and sensitive model bioassay for the evaluation of phosphate pollutants in marine systems. Our findings also indicate that shallow-water populations of L. variegatus spawning in areas subjected to inorganic and organic phosphate pollutants may suffer detrimental effects on fertilization and embryonic development.

Effects of inorganic and organic phosphates on feeding, feeding absorption, nutrient allocation, growth and righting responses of the sea urchin Lytechinus variegatus

The sea urchin Lytechinus variegatus is capable of surviving chronic exposure to sodium phosphate (inorganic phosphate) concentrations as high as 3.2 mg l−1, and triethyl phosphate (organic phosphate) concentrations of 1,000 mg l−1. However, chronic exposure to low (0.8 mg l−1 inorganic and 10 mg l−1 organic phosphate), medium (1.6 mg l−1 inorganic and 100 mg l−1 organic phosphate) or high (3.2 mg l−1 inorganic and 1,000 mg l−1 organic phosphate) sublethal concentrations of these phosphates inhibits feeding, fecal production, nutrient absorption and allocation, growth and righting behavior. Food consumption and fecal production declined significantly in individuals exposed to medium and high concentrations of inorganic phosphates and all levels of organic phosphates. Feeding absorption efficiencies for total organics and carbohydrates decreased significantly in individuals held in the highest concentration of organic phosphate. Feeding absorption efficiencies for lipids were significantly reduced in the highest inorganic phosphate concentration only, while they decreased significantly for protein with increasing phosphate exposure. Carbohydrate and lipid levels in gonad and gut tissues decreased significantly with exposure to increasing phosphate concentrations, potentially impairing both gametogenesis and nutrient storage in the gut. Moreover, gonad indices significantly decreased in individuals exposed to the highest concentrations of either phosphate. Growth rates decreased significantly under the influence of all phosphate concentrations, while increasing in seawater alone. Individuals exposed to increasing phosphate concentrations showed reduced righting responses (a measure of stress) and no acclimation in righting times during chronic exposure to phosphates over a 4 week period. These findings indicate that shallow-water populations of L. variegatus subjected to inorganic and organic phosphate pollutants will exhibit stress and be inhibited in their growth and performance due to reductions in feeding, nutrient absorption and allocation of nutrients to key somatic and reproductive tissues.

The potential for phosphorus pollution remediation by calcite precipitation in UK freshwaters

Abstract. This paper examines the potential for calcium carbonate to reduce phosphate pollution in freshwaters by co-precipitation, a process known as a "self cleansing mechanism". Calcium carbonate saturation levels and phosphate concentrations (SRP - soluble reactive phosphate) across the major eastern UK river basins are examined to test for solubility controls. The study shows that calcite saturation varies for each catchment as a function of flow and biological activity rather than by direct regulation by SRP. Indeed, there is no evidence, for any of the rivers studied, that calcite solubility controls hold. However, for groundwater and groundwater-fed springs in the Chalk of the Thames basin, calcite saturation is observed with associated low SRP levels. A self-cleansing mechanism may well be operative within the Chalk due to two factors. Firstly, there is a high potential for nucleation on the calcite micro-crystals in the aquifer. Secondly, there are within aquifer reactions that remove the calcite nucleating inhibitors (SRP and dissolved organic carbon, DOC) to levels lower than those occurring within the rivers do. These inhibitors enter the catchment at very high concentrations in association with agricultural pollution (fertilizer application and animal slurry) and household contamination (e.g. sewage sources from septic tanks). Under low flow conditions, when the saturation index for calcite is at its highest, so too is the concentration of the nucleation inhibitor SRP. Companion work shows that calcite precipitation can occur at the water-sediment interface of the river and this may involve SRP removal. The data, as a whole, define an apparent bound for calcite solubility control where in the presence of nucleating centres, SRP must be less than 4 mM-P l-1 and DOC must be less than 150 mM-C l-1: a condition that does not seem to pertain within most UK rivers. Keywords: calcite, calcium carbonate, phosphate, soluble reactive phosphate, dissolved organic carbon, LOIS, UK, rivers, self-cleansing mechanisms.

Crystal structures of a novel, thermostable phytase in partially and fully calcium-loaded states.

Phytases hydrolyze phytic acid to less phosphorylated myo-inositol derivatives and inorganic phosphate. A thermostable phytase is of great value in applications for improving phosphate and metal ion availability in animal feed, and thereby reducing phosphate pollution to the environment. Here, we report a new folding architecture of a six-bladed propeller for phosphatase activity revealed by the 2.1 A crystal structures of a novel, thermostable phytase determined in both the partially and fully Ca2+-loaded states. Binding of two calcium ions to high-affinity calcium binding sites results in a dramatic increase in thermostability (by as much as approximately 30 degrees C in melting temperature) by joining loop segments remote in the amino acid sequence. Binding of three additional calcium ions to low-affinity calcium binding sites at the top of the molecule turns on the catalytic activity of the enzyme by converting the highly negatively charged cleft into a favorable environment for the binding of phytate.

Phosphate pollution in the groundwater of lower Vamsadhara river basin, India

The lower Vamsadhara river basin, spreading over an area of 817 sq.km in northern Andhra Pradesh, represents a typical rural setting. The occurrence of phosphorus-bearing minerals reported in literature, and the increasing application of phosphatic fertilizers in the area have prompted these studies. Water samples from 113 wells were analysed for Ca, Mg, Na, K, Cl, SO4, HCO3, F, NO3 and PO4. The results indicate the presence of phosphate in the groundwater ranged from 0.72 to 7.07 mg/l, which is beyond the limits recommended for domestic and water treatment purposes. Samples of soils and weathered rocks were analyzed for their water-soluble phosphate and other chemical parameters. The water-soluble phosphate in the widely used fertilizers of the area was determined. The spatial variation of phosphate in the aquifer and the soil leachate characteristics supplemented by the chemical equilibrium calculations clearly indicate the dominance of geological sources over the fertilizer sources in contributing PO4 to the groundwaters.

Studies of IGA intergranular attack/stress corrosion cracking related parameters and remedies

The parameters influencing the appearance of intergranular corrosion of steam generator tubes are examined: the sludge zone located above the tube sheet, the secondary system materials (copper alloys), the age of the unit and the design of the tube support plates, which plays an important role in the hide out and in the hide out return of chemical species. The occurrence of intergranular attack/stress corrosion cracking (IGA/SCC) as a function of chemical parameters is also examined. These parameters include the following: sodium hydroxide, partly brought by the cooling water condenser inlets or by makeup water pollution, calculations of pH at high temperature in zones of restructed flow show a generally alkaline tendency; lead, often found on cracked tubes at particularly high concentrations, and well known as an aggravating element; copper, found in abnormal quantities on tubes pulled from Fessenheim unit 1, thus the relation between the materials of the secondary system, the copper concentrations on pulled tubes and the presence of IGA is carefully studied too; phosphate pollution, generally brought by the intermediate cooling system. Finally, the remedies implemented by EDF to limit the degradations with time are described.

Impact of phosphorus loadings on macro-algal communities in the Red Sea coast of Egypt

This study was undertaken to investigate the impact of phosphorus loadings on the seasonal abundance and diversity of macro-algal communities at three sites of the Egyptian coastal region of the Red Sea. Sea-water analysis revealed no significant variations in the levels of dissolved inorganic carbon at these sites. Nitrate content was highest during the winter season especially at Ghardaqa. The localized phosphate pollution at the two other sites significantly increased the phosphate level in water which led to significant decreases in biomass of the macroalgae as compared to Ghardaqa. The intertidal zone at one of the impacted sites supported very poor algal vegetation, dominated by Phaeophyta in winter and spring and Rhodophyta in summer and autumn; at Quseir it was dominated by microfilamentous Rhodophya. At Ghardaqa, the intertidal macro-algal community was dominated by Phaeophyta. The results also showed that the abundance of marcroalgae reached its maximum in August at all the study sites, and that species diversity was significantly higher at Quseir than at the other two sites.

Animal excreta: fertilizer or pollutant?

The difficulty of reconciling human food production and safeguarding the environment is well illustrated by nitrate and phosphate pollution resulting from animal excreta. Animal excreta contain, at the point of application to the land, some 4 g N, 2 g P, and 2.5 g K per kg. The average output from a pig, for example, is some 2000 kg excreta per annum, and the capacity of crops to utilize N and P is about 150 kg and 100 kg per hectare per annum respectively. Thus crops can utilize per hectare per annum the nutrients from about 20 pigs. Overapplication has resulted in the need for legislation in order to limit the amount of excreta applied to agricultural land. But the material itself is the essential mainstay of organic and sustainable farming initiatives, allowing food production with avoidance of artificial aids and minimizing the use of non-renewable resources. It is not that there is too much excreta; rather the problem is one of concentration caused by the location of many intensive livestock units in...

FACTORS AFFECTING PHOSPHATE UPTAKE BY PEAT SOILS OF THE FLORIDA EVERGLADES

The Florida Everglades constitutes a unique, historically oligotrophic ecosystem threatened by the effects of phosphate (PO4) pollution resulting from agricultural runoff. The present study was designed to determine its capacity to remove PO4 from solution and to study the effects of total P content of the soil, PO4 concentration of the water, autoclaving, and glucose and ammonium addition on PO4 removal by neutral peats of the Florida Everglades. Samples of peat soils were obtained from an area impacted by water with a high total P content and an unimpacted area, both within Everglades National Park. PO4 removal was determined by passing a solution containing a known PO4 concentration (0 to 12.5 μM) through a soil column and measuring the difference in concentration between the influent and effluent solutions over time. Removal rates for both soils were nearly constant with time at the lower PO4 concentrations but decreased with time at higher PO4 concentrations. The initial rate and the extent of removal increased linearly with PO4 concentration; these values were consistently higher for the soil from the unimpacted site than for the impacted site. Autoclaving the unimpacted soil diminished the initial rate and extent of PO4 removal by the soil. Addition of 100 μM NH4Cl to the unimpacted soil increased the removal of P from 1.0 and 10.0 μM solutions. Glucose (15 mg C L−1) had no effect on the removal from 2.5 and 10.0 μM PO4 by the unimpacted soil. PO4 removal in natural peats is controlled by a combination of biotic and abiotic processes, the relative importance of which is determined by the concentration of PO4 in the water.

Phosphate pollution in the Jordan Gulf of Aqaba

In order to assess the magnitude of phosphate pollution in the Jordanian sector of the Gulf of Aqaba, the distribution of total phosphorus, fluoride, calcium and calcium carbonate and their association with each other were determined in sediments collected from seven stations north and south of Aqaba Port. Abnormally high values were found near the phosphate loading berth which decrease with increasing distance from the berth. The results indicate that phosphate pollution is mainly localized in the vicinity of the loading berth although its influence may be detected in other areas along the coast. The level of pollution had increased by at least an order of magnitude since 1978.