Calcium Phosphate Species Research Articles

Preparation of Calcium Phosphate Compounds on Zirconia Surfaces for Dental Implant Applications.

Titanium is widely used in medical implants despite the release of heavy metal ions over long-term use. Zirconia is very close to the color of teeth; however, its biological inertness hinders bonding with bone tissue. Alkaline treatment and coatings of calcium phosphate can be used to enhance bone regeneration adjacent to dental implants. This study examined the effects of alkaline treatment, calcium phosphate coatings, and sintering, on the physical properties of implant material. Our analysis confirmed that the calcium phosphate species were octacalcium phosphate (OCP). The sintering of calcium phosphate was shown to create B-type HAP, which is highly conducive toward the differentiation of mesenchymal stem cells (MSCs) into osteoblasts for the facilitation of bone integration. Conclusions: This study demonstrated the room-temperature fabrication of dental implants with superhydrophilic surfaces to enhance biocompatibility.

Detection of calcium phosphate species in soil by confocal μ‐Raman spectroscopy#

AbstractBackgroundRaman spectroscopy is a promising but largely underexplored tool for the detection of phosphates (P) in soil. Although it requires minimal sample preparation, it has been demonstrated mainly in test matrices or substrates to circumvent the typical signal interference caused by fluorescence of organic matter in actual agricultural soils.AimsThe aim of this study was to highlight the Raman spectroscopic detection and identification of distinct calcium phosphate species amended in contrasting soil matrices—including a real arable soil.MethodsPure calcium dihydrogen phosphate [Ca(H2PO4)2·H2O], calcium hydrogen phosphate (CaHPO4), and β‐tricalcium phosphate [β‐Ca3(PO4)2] were each amended in Luvos® healing earth, loess from a C‐horizon, and a loam arable soil from an Ap‐horizon at a dose of 1 mmol (10 g soil)–1. The unique Raman signature of each pure calcium phosphate species was determined by confocal μ‐Raman spectroscopy and used subsequently as a reference spectrum to identify the compound in each soil matrix. Controls without added P were also analyzed.ResultsCa(H2PO4)2·H2O, CaHPO4, and β‐Ca3(PO4)2 were each unambiguously detected in the treated soils. Native hydroxyapatite [Ca5(PO4)3(OH)], quartz (SiO2), feldspar (NaAlSi3O8), calcite (CaCO3), and dolomite [CaMg(CO3)2] were also identified, for example, in the Raman microscopic image of the control Luvos® healing earth sample. Intrinsic β‐Ca3(PO4)2 and Ca5(PO4)3(OH) present in Ap‐horizon loam were detected and distinguished from each other by a Lorentzian fitting, which deconvoluted the individual Raman signals from an unresolved peak.ConclusionsThe usefulness of confocal μ‐Raman spectroscopy to detect distinct P species present in agricultural soil could be shown as a proof of concept.

In-situ study of the kinetics of phosphoric acid interaction with calcite and fluorapatite by Raman spectroscopy and flotation

In the reverse anionic flotation of phosphate ores using phosphoric acid, it is often suggested that a selective surface passivation of the phosphate minerals by calcium phosphate occurs. Several calcium phosphate species have been proposed in the literature for this surface passivation. In this study, in-situ Raman spectroscopy was used to monitor as a function of time the interaction of phosphoric acid with calcite and fluorapatite at a fixed pH of 4.5 or at fixed phosphoric acid concentrations in order to identify what species have formed in conditions similar to those used in flotation. X-ray photoelectron spectroscopy was also used to confirm and identify more clearly the species formed at the minerals surface. Although a calcium phosphate (1:1) species was observed on both minerals, its presence on calcite was highly dependent on phosphoric acid concentration and pH as the latter controls both calcium dissolution and calcium phosphate precipitation. The results of mineral flotation have confirmed the importance of phosphate concentration in solution, originating from phosphoric acid addition and/or mineral dissolution, in the formation/precipitation of calcium phosphate which can turn on or off the flotation of calcite or fluorapatite, or both.

Dependence of Phosphorus Recovery on Acid Type during Dissolution–Precipitation Treatment of Incineration Ash of Chicken Manure

In order to utilize chicken manure as a source of phosphorus, we used dissolution-precipitation treatment to recover phosphorus from the incineration ash of chicken manure (IACM), which was used as fuel to power a boiler. In order to recover useful phosphorus-containing solids from IACM, it was dissolved into aqueous solutions of either nitric acid, hydrochloric acid, or sulfuric acid to elute phosphorus together with various component elements, followed by the use of aqueous NH3 to form a precipitate containing phosphorus. In using nitric acid and hydrochloric acid, calcium phosphate species such as calcium hydroxyapatite (Ca10(PO4)6(OH)2) and monetite (CaHPO4) were obtained following the precipitation treatment. By contrast, the use of sulfuric acid resulted in the precipitation of magnesium ammonium phosphate (MAP) species such as struvite (MgNH4PO4∙6H2O) and dittmarite (MgNH4PO4∙H2O). Both the calcium phosphate and MAP species can be used as a slow-acting fertilizer containing phosphorus, while the MAP species could be simultaneously used as a slow-acting fertilizer containing nitrogen. It is noteworthy that the calcium phosphate species obtained in the present study was equivalent to phosphate rock, which is widely used as a raw material in phosphorous-based industries, and the natural sources of this material could be depleted in the near future. Though IACM has not been used effectively until now, this new resource shows promise as s viable alternative to the dwindling supply of the natural sources of phosphorus.

Investigating mineralization species in cultured bone from human mesenchymal stem cells using synchrotron-based XANES

In this context, we successfully demonstrate the use of X-ray absorption near edge spectroscopy (XANES) to identify calcium species and compare the mineralization of bone-like materials from human mesenchymal stem cells (MSC) in 3 culture conditions in vitro; non-osteogenic medium (non-OM), osteogenic medium (OM) and OM supplemented with bone morphogenetic protein 9 (OM-BMP9). X-ray photoelectron spectroscopy (XPS) was also used to examine the bonding of mineralized species on the surface of MSC-mediated mineralization. The results from Alizarin Red staining exhibited calcium deposits in all 3 culture conditions with different degrees of calcium deposition (OM-BMP9> OM > non-OM). While XANES disclosed that the majority of calcium species deposited in the non-OM culture was calcium sulfate (CaSO4; 27.7%), tricalcium phosphate (TCP; 27.1%) and calcium chloride (CaCl2; 22.2%) with lower levels of calcium carbonate (CaCO3; 10.5%) and calcium hydroxide (Ca(OH)2; 12.5%). Hydroxyapatite (HA) was not detected in the non-OM sample. On the other hand, the majority of calcium species in OM and OM-BMP9 cultures presented in calcium phosphate forms. The amount of calcium species in the OM-BMP9 culture comprised 33.1% HA, 40.5% TCP, 5.7% CaCl2, 15.4% CaSO4, and 5.0% CaCO3 and the OM culture comprised 22% HA, 33.5% TCP, 8.5% CaCl2, 24.3% CaSO4, 5% CaCO3 and 3.9% Ca(OH)2. Amorphous calcium phosphate (APC) was not detected in all the 3 groups. XPS results confirmed the existence of calcium phosphate species on the surface of MSC-mediated biomineralization. The successful use of XANES and XPS to qualitatively and quantitatively determine calcium phosphates in vitro is highly beneficial and provides not only an insight into chemical composition of the mineral deposit in the cultured bone but also presents more biologically-relevant information than those from conventional analytical methods. This is also the first report to demonstrate, by synchrotron-based XANES, the osteogenic role of BMP9 in enhancing HA formation specifically. This will help optimizing culture conditions to produce highly osteogenic bone-like materials containing similar compositions and functions to native human bone.

Recovery of Phosphate Rock Equivalents from Incineration Ash of Chicken Manure by Elution-Precipitation Treatment

In order to obtain calcium phosphates - a phosphate rock equivalent - from the incineration ash of chicken manure, which is obtained from power generation systems that use the manure for fuel, incineration ash was treated with an aqueous solution of nitric acid to elute phosphorus. By using 0.3 M of HNO3, most of the phosphorus could be eluted from 1.0 g of ash within 0.1 h. Compared with the composted chicken manure that was previously examined in our laboratory, the concentration of HNO3 was increased for this session of elution. Using the incineration ash of chicken manure made it possible to remove inorganic species at a lower boiling or sublimation temperature, and organic species by calcination in the power generation system. Compared with composted chicken manure, the concentrations of phosphorus contained in the incineration ash and the nitric acid extract were higher in the incineration ash. XRD analysis showed that the obtained nitric acid extract could be treated with aqueous NH3 to form a precipitation of poorly-crystallized calcium hydroxyapatite (Ca10(PO4)6(OH)2), which is one of main components in phosphate rock. In order to confirm the formation and purity of calcium phosphate species, the precipitation calcination was conducted at 1,078 K for 5 h. XRD revealed that the calcined solid was tricalcium phosphate, and no contamination was evident. These results reveal that a phosphate rock equivalent could be easily obtained from the incineration ash of chicken manure, which means that approximately 14% of the phosphate rock that is currently being imported into Japan could be replaced by this product.

Simulation of Calcium Phosphate Species in Aqueous Solution: Force Field Derivation.

A new force field has been derived for the aqueous calcium phosphate system that aims to reproduce the key thermodynamic properties of the system, including free energies of hydration of the ions and the solubility of the solid mineral phases. Interactions of three phosphate anions (PO43-, HPO42-, and H2PO4-) with water were calibrated through comparison with the results obtained from ab initio molecular dynamics using both GGA and hybrid density functional theory with dispersion corrections. In the solid state, the force field has been evaluated by benchmarking against experiment and other existing models and is shown to reproduce the structural and mechanical properties well, despite the primary focus being on thermodynamics. To validate the force field, the thermodynamics of ion pairing for calcium phosphate species in water has been computed and shown to be in excellent agreement with experimental data.

The effect of crystal structure of TiO2 nanotubes on the formation of calcium phosphate coatings during biomimetic deposition

The crystallization process of bioactive calcium phosphate (CaP) species via biomimetic deposition onto anodic TiO2 nanotubes is investigated. The porous surface of nanostructured TiO2 provides an ideal substrate for CaP crystallization. The compositions of CaP coatings are studied using X-ray absorption near-edge structures (XANES) at the Ca K-edge. Using detection modes with different probing depths, both the surface of the CaP coating and the CaP-TiO2 interface are simultaneously analyzed. Calcium phosphate (CaP) species, such as hydroxyapatite (HAp), octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O, OCP), brushite (CaHPO4·2H2O, DCPD), and amorphous calcium phosphate (ACP), are found in the CaP coatings. TiO2 nanotubes of amorphous and anatase phases are comparatively studied to determine their effect on the efficiency of CaP formation and the phase transformation among CaP species in prolonged deposition time. It is found the composition of CaP coating has a strong dependency on the crystal structure of TiO2 substrate and the kinetics (deposition time).

The effect of pH on phosphorus availability and speciation in an aquaponics nutrient solution

The interaction between the main ions in aquaponics nutrient solutions affects chemical composition and availability of nutrients, and nutrient uptake by plant roots. This study determined the effect of pH on phosphorus (P) speciation and availability in an aquaponics nutrient solution and used Visual MINTEQ to simulate P species and P activity. In both experimental and simulated results, P availability decreased with increase in pH of aquaponics nutrient solutions. According to simulations, P binds to several cations leaving less free phosphate ions available in solution. High pH values resulted in the formation of insoluble calcium phosphate species. The study also demonstrated the importance of organic matter and alkalinity in keeping free phosphate ions in solution at high pH ranges. It is recommended though that pH in aquaponics systems is maintained at a 5.5–7.2 range for optimal availability and uptake by plants.

Can European Sea Bass (<i>Dicentrarchus labrax</i>) Scale Be a Good Candidate for Nano-Bioceramics Production?

Bioceramics are commonly used biomaterials for orthopedic and dental applications. Among these bioceramics, hydroxyapatite (HA) and tricalcium phosphate (TCP) are of interest and are used in various biomedical applications. Production of bioceramics from natural materials such as bovine and sheep bones with calcination method, is possible. Lately, fish scales become an alternative biological source for bioceramic production. The present study proposes an approach to obtain HA bone-scaffolds from European Sea Bass (Dicentrarchus labrax) scales aiming to provide nano-biomaterials via calcination method. Untreated fish scales are obtained and are carefully cleaned from their meat and grease. They are washed with alkaline water several times and calcinated at 850°C for 4 hours. Energy Dispersive Spectroscopy (EDS), X-ray diffraction analysis, Scanning Electron Microscopy (SEM) studies are performed. Various calcium phosphate species (HA, TCP) are identified in the study. SEM images prove the presence of the nano-scale structures. This study indicates calcination as a simple way of nano-scale bioceramic production for drug delivery and tissue engineering applications. Being produced from wastes of a sustainable and cheap source, these bioceramics can be good candidates for future clinical applications.

Technical Note: An X-ray absorption method for the identification of calcium phosphate species using peak-height ratios

Abstract. X-ray absorption near edge structure (XANES) studies on calcium phosphate species (Ca-P) deal with marginal differences among subtle spectral features despite a hitherto missing systematic breakdown of these differences. Related fingerprinting approaches depend, therefore, on spectral libraries that are not validated against each other, incomplete and scattered among publications. This study compiled a comprehensive spectral library from published reference compound libraries in order to establish more clear-cut criteria for Ca-P determination by distinctive phosphorus K-edge XANES features. A specifically developed normalization method identified diagnostic spectral features in the compiled library, e.g. by uniform calculation of ratios between white-line and secondary peak heights. Post-processing of the spectra (n = 81) verified distinguishability among most but not all phases, which included hydroxylapatite (HAP), poorly crystalline HAP, amorphous HAP, fluorapatite, carbonate fluorapatite (CFAP), carbonate hydroxylapatite, β-tricalcium phosphate, octacalcium phosphate (OCP), brushite, monetite, monocalcium phosphate, amorphous calcium phosphate (ACP), anapaite, herderite, scholzite, messelite, whiteite and P on CaCO3. Particularly, peak-height ratios significantly improved analyte specificity, e.g. by supplementary breakdown into OCP and ACP. The spectral analysis also revealed Ca-P standards that were rarely investigated or inappropriately synthesized, and thus provides a basis for standard selection and synthesis. The method developed and resulting breakdown by species were subsequently tested on Ca-P spectra from studies on bone and sediment. The test indicated that bone material likely comprises only poorly crystalline apatite, which confirms direct nucleation of apatite in bone. This biological apatite formation is likely opposed to that of sedimentary apatite, which apparently forms by both direct nucleation and successive crystallization. Application of the method to μXANES spectra of sediment particles indicated authigenic apatite formation by an OCP precursor.

Electrochemistry of calcium precipitating bacteria in orthodontic wire

BackgroundCalculus composed of inorganic and organic components with bacteria formed on teeth gets deposited on orthodontic wires. The reason for calculus formation and impact of calcium precipitating bacteria (CPB) on orthodontic wire were studied. A pilot study on electrochemical characterization of CPB on orthodontic wires was done. MethodsCPB were isolated from orthodontic patients and identified by molecular techniques. The electrochemical behavior of two isolates (CPB-1 and CPB-3) on orthodontic wires was studied by employing polarization and impedance techniques. The CPB morphology by scanning electron microscopy and chemical characterization of CPB and tooth pulp stone were studied by Fourier transform infrared (FTIR) and X-ray diffraction (XRD). ResultsThe two isolates Bacillus megaterium (CPB-1) and Paenibacillus sp. (CPB-3) identified with 16S rRNA sequencing method increased pH of B4 medium from 5.32 to 8.3. The carboxylic acid and phosphate groups identified in FTIR analysis acted as nucleation sites for calcium deposition. The biogenic crystal phases identified in teeth pulp stone by XRD were similar to bacterial isolates cultured in the laboratory. The electrochemical studies with two CPB species revealed that biogenic calcium phosphate species act as cathodic inhibitors on orthodontic wire. ConclusionThe present study concluded that teeth pulp stone formation is due to CPB and high pH determines the mineralization process. Diffusion process and dispersive capacitive behavior indicate that the chloride ions may penetrate through calcium deposits and initiate pitting corrosion on orthodontic wire which may enhance the leaching of toxic elements in saliva.

A novel and easy-to-prepare strontium(II) modified calcium phosphate bone cement with enhanced mechanical properties

The aim of this study was to evaluate two different approaches to obtaining strontium-modified calcium phosphate bone cements (SrCPCs) without elaborate synthesis of Sr-containing calcium phosphate species as cement precursors that could release biologically effective doses of Sr2+ and thus could improve the healing of osteoporotic bone defects. Using strontium carbonate as a strontium(II) source, it was introduced into a hydroxyapatite-forming cement either by the addition of SrCO3 to an α-tricalcium phosphate-based cement precursor mixture (A-type) or by substitution of CaCO3 by SrCO3 during precursor composition (S-type). The cements, obtained after setting in a water-saturated atmosphere, contained up to 2.2at.% strontium in different distribution patterns as determined by time-of-flight secondary ion mass spectrometry and energy-dispersive X-ray spectroscopy. The setting time of CPC and A-type cements was in the range of 6.5–7.5min and increased for substitution-type cements (12.5–13.0min). Set cements had an open porosity between 26 and 42%. Compressive strength was found to increase from 29MPa up to 90% in substituted S-type cements (58MPa). SrCPC samples released between 0.45 and 1.53mgg−1 Sr2+ within 21days and showed increased radiopacity. Based on these findings, the SrCPC developed in this study could be beneficial for the treatment of defects of systemically impaired (e.g. osteoporotic) bone.

Boron removal and recovery from concentrated wastewater using a microwave hydrothermal method

Boron compounds are widely-used raw materials in industries. However, elevated boron concentrations in aqueous systems may be harmful to human and plants. In this study, calcium hydroxide (Ca(OH)2) alone and Ca(OH)2 with phosphoric acid (H3PO4) addition (P-addition) were used to remove and recover boron from wastewater using hydrothermal methods. A microwave (MW) hydrothermal method was used and compared with the conventional heating (CH) method in batch experiments. Physicochemical properties of the precipitates obtained from both methods were analysed by XRD, SEM with EDX and BET. For the case of Ca(OH)2 alone and the MW method, experimental results showed that boron recovery efficiency reached 90% within 10min, and crystals of Ca2B2O5·H2O were found in the precipitates as indicated by the XRD analysis. For the case of P-addition and the MW method, boron recovery efficiency reached 99% within 10min, and calcium phosphate species (CaHPO4·H2O, CaHPO4 and Ca10(PO4)6(OH)2) were formed. The experimental results of this study indicate that the required reaction time of the MW method was much less than that of the CH method, and the MW method is an effective and efficient method for boron removal and recovery from concentrated wastewater.

Synthesis and in vitro bioactivity of ordered mesostructured bioactive glasses with adjustable pore sizes

Four ordered mesoporous bioactive glasses (MBGs) with the same composition and hexagonal mesostructure but adjustable pore diameters (1.9, 3.4, 5.0, 6.4 nm, denoted MBGs A–D, respectively) have been prepared for the first time by using different structure-directing agents as templates. Their in vitro bioactivities have been carefully studied by investigating the formation of hydroxycarbonate apatite (HCA) on MBG surfaces. MBG A with the smallest pore diameter (1.9 nm) shows the fastest nucleation rate of HCA, however, the total amount of calcium phosphate (CaP) species deposited after immersing in SBF for 2 days is the smallest among four MBG samples under study. The in vitro bioactivity sequence of MBGs with different pore sizes is determined to be MBG C ≈ D > B > A in terms of the total amount of CaP species deposition. MBG A has the highest surface area and thinnest wall thickness, which favor the rapid release of Ca and P species from the wall framework and thus fasten the nucleation rate. Nevertheless, the small pore of MBG A may be easily blocked by the nucleates, which is disadvantageous for the subsequent ionic diffusion and crystal growth of HCA. Our results have indicated that the fast nucleation does not necessarily correlate to a high amount of HCA deposition, which is important in the evaluation of the in vitro bioactivity of BG-related biomaterials. By understanding the relationship between the pore structure and the in vitro bioactivity, it is anticipated that MBGs with controllable mesostructure and enhanced bioactivity can be designed and fabricated.

Synthesis of lamellar mesostructured calcium phosphates using n-alkylamines as structure-directing agents in alcohol/water mixed solvent systems

Lamellar mesostructured calcium phosphates constructed by ionic bonds were prepared by using n-alkylamines (n-CnH2n+1NH2, n = 8–18) at room temperature in the mixed solvent systems of aliphatic alcohol (CnH2n+1OH, n = 1–4) and water, and the synthetic conditions were investigated in detail. The mixed solvent systems suppressed the formation of crystalline calcium phosphates like brushite (CaHPO4·2H2O) and monetite (CaHPO4) at low temperatures, successfully affording pure lamellar mesostructured calcium phosphates. Other crystalline phases such as hydroxyapatite (Ca10(PO4)6(OH)2) were not formed under the conditions with the Ca/P molar ratios in the range of 0.7–1.0 in the starting mixtures. The Ca/P molar ratio of the lamellar mesostructured calcium phosphates was ca. 1.0, calculated by ICP and 31P MAS NMR data. Interestingly, the kind of alcohols strongly influenced the solubilities of calcium phosphate species and n-alkylamines, and then lamellar mesostructured phases were obtained with some morphological variation.

Biocompatibility Evaluation of Porous Si-Containing Hydroxyapatite Derived from Coral

A porous silicon-containing hydroxyapatite has been prepared using natural coral as a calcium source to obtain a biomaterial having an improved biocompatibility. From the XRD analysis, it was confirmed that the single-phase hydroxyapatite containing silicon has formed without revealing the presence of extra phases related to silicon dioxide or other calcium phosphate species. Silicon content is ranged from 0.5wt% to 1wt% by weight. The porous silicon-containing hydroxyapatite blocks were inserted into the 5mm diameter of drill holes made through the lateral femoral condyles of New Zealand white rabbits. The new bony formation did not begin after 1 week. At 3 week, bony ongrowth to the inserted porous silicon-containing hydroxyapatite block could be found, and the new bone surrounded the inserted block entirely after 24weeks. Based on in-vivo test, Si-containing porous hydroxyapatite derived from coral possesses high biodegradability and can be considered a useful material for bone implants.

The effect of citrate on calcium phosphate deposition from simulated milk ultrafiltrate (SMUF) solution

As has been widely reported, different calcium phosphate phases can be formed in solution depending on several physical-chemical aspects like the concentration of free calcium and phosphate ions, pH of the solution, temperature and the presence of interfering ions. The present work aims at studying the effect of pH and of citrates on the precipitation of calcium phosphate in a solution that simulates the mineral composition of milk (SMUF), as well as the subsequent effect on the deposition on stainless steel surfaces. The different calcium phosphate species formed during heating at different pH values and in the presence or absence of citrate were characterized by scanning electron microscopy, X-ray microanalysis and X-ray diffraction. Their fouling behaviour was characterized according to the amount of deposit formed on stainless steel surfaces and to the deposit’s resistance to removal by hydrodynamic shear forces. The absence of citrate was responsible for the decrease in the solution pH and for the formation of a crystalline dicalcium phosphate dihydrate structure with a deposited mass which was almost twice the one obtained in the presence of citrate.

Preparation of porous Si-incorporated hydroxyapatite

Abstract A porous silicon-incorporated hydroxyapatite has been prepared using natural coral as a calcium source to obtain a biomaterial having a good biocompatibility. Si-incorporated hydroxyapatite has been prepared by hydrothermal treatment in 2 M (NH4)2HPO4 and solvothermal treatment in silicon acetate saturated acetone solution at 180 °C of the natural coral repeatedly. From the XRD analysis, it was confirmed that the single-phase hydroxyapatite containing silicon has formed without revealing the presence of extra phases related to silicon dioxide or other calcium phosphate species. Compressive strength of the porous silicon-incorporated hydroxyapatite was 5.5 MPa and silicon content was ranged from 0.12% to 0.19% by weight. SEM and EDS investigation confirmed the presence of silicon in the framework of hydroxyapatite structure.

Species and mobility of phosphorus and nitrogen in a wadi–aquifer relationship

The problems of urban effluent discharged in wadis represents the thorny question of their impact on the groundwaters in relationship with these water courses. This aspect becomes crucial when several drinking water-catchments are located nearby the wadi banks. Such a case was observed in the low Seybouse plain (North-Eastern Algeria) where a natural obstruction of the wadi produced a rising of the water level, and concomitant direct infiltrations from the wadi to the aquifer. Two wells (MP1 and MP2) underwent a phosphate contamination from the wadi. Several water field samplings of the wadi (shallow waters), with a monthly period (Station MO1) and of the groundwater on two test sites (MP1 and MP2), with MP2 being discontinuously pumped (6 h d −1), were achieved during the water year, from February to December 1999. Comparing the chemical composition of the wadi water with that of several tapped groundwater samples, we could observe the existence of two pollutants in the wadi: phosphate (23 mg l −1) and ammonium (54 mg l −1). On the other hand, in the water catchments, only phosphate could be observed, and it could move only under the same chemical species between the wadi and both wells, where the concentrations reached, respectively, 2.3 and 3.1 mg l −1. The lowering of the phosphate concentration between the wadi and the wells is due to the dilution effect of the contents by the aquifer water, the precipitation of phosphate under calcium phosphate species and finally by clay adsorption. But then, the absence of ammonium in the wells is due to the transformation of the nitrogen species into nitrate during the water pathway between both media, under the effect of oxidizing conditions.