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1.
The character of solubility of 61 metamorphic and metasomatic minerals in an aqueous fluid was analyzed as a function of temperature, pressure, and fluid acidity by means of computer simulation of mineralfluid equilibria. Depending on the behavior of minerals in solutions of varying acidity, six main types of solubility diagrams were distinguished. The solubility of the majority of minerals is controlled mainly by fluid acidity rather than by P–T conditions. The analysis of model results provided insight into the mobility of chemical elements composing the minerals. The highest mobility in solutions of any acidity was established for Si, K, and Na. Ca and Mg are mobile in acidic solutions and inert in neutral and alkaline solutions. Fe(II) and Mn(II) are mobile in acidic and alkaline solutions but inert in neutral solutions. Fe(III) is mobile only in strongly acidic solutions and practically immobile in solutions of other compositions, which suggests that ferrous iron species must prevail in solutions. Al is mobile in alkaline and ultra-acidic solutions but inert in neutral and slightly acidic solutions. Correspondingly, a change in acidity must lead to the migration of some component into the solution and precipitation of other components. These conclusions are in agreement with the sequences of element mobility deduced from the experimental investigation of metasomatism. Most metamorphic fluids must be rich in silica and alkalis, which may result in the appearance of aggressive silica-alkali fluids responsible for regional metasomatism and granitization. In general, the solubility of Fe-, Mg-, Mn-, and Ca-bearing minerals in alkaline solutions is low compared with acidic solutions. Therefore, only acidic initial solutions could produce fluids enriched in these elements at the expense of leaching from metamorphic rocks during fluid migration. Fluids enriched mainly in Fe could initially be both acidic and alkaline. 相似文献
2.
Kevin H. Johannesson W. Berry Lyons Klaus J. Stetzenbach Robert H. Byrne 《Aquatic Geochemistry》1995,1(2):157-173
Rare earth element (REE) concentrations in alkaline lakes, circumneutral pH groundwaters, and an acidic freshwater lake were determined along with the free carbonate, free phosphate, and free sulfate ion concentrations. These parameters were used to evaluate the saturation state of these waters with respect to REE phosphate and carbonate precipitates. Our activity product estimates indicate that the alkaline lake waters and groundwaters are approximately saturated with respect to the REE phosphate precipitates but are significantly undersaturated with respect to REE carbonate and sulfate precipitates. On the other hand, the acidic lake waters are undersaturated with respect to REE sulfate, carbonate, and phosphate precipitates. Although carbonate complexes tend to dominate the speciation of the REEs in neutral and alkaline waters, our results indicate that REE phosphate precipitates are also important in controlling REE behavior. More specifically, elevated carbonate ion concentrations in neutral to alkaline natural waters tend to enhance dissolved REE concentrations through the formation of stable REE-carbonate complexes whereas phosphate ions tend to lead to the removal of the REEs from solution in these waters by the formation of REE-phosphate salts. Removal of REEs by precipitation as phosphate phases in the acid lake (pH=3.6) is inconsequential, however, due to extremely low [PO
4
3–
]
F
concentrations (i.e., 10–23 mol/kg). 相似文献
3.
一些有机物对Ph、Zn、Cu迁移与沉积作用的实验研究 总被引：1，自引：0，他引：1
根据一些有机物在成矿溶液中存在的可能性,作者相继就中性、酸性与碱性氨基酸,以及酒石酸在铅、锌、铜迁移与沉积过程中的作用,进行了模拟实验研究。结果表明,在从９０～２１０℃范围内,酸性氨基酸在热卤水中的存在,比中性和碱性氨基酸更有利于铅、锌、铜的活化、迁移。而酒石酸在热卤水中的存在,只在９０℃或更低时,才是铅、锌等金属活化、迁移的最佳温度条件。且无论哪种有机物在热卤水中的存在,随作用时间及温度的变化,不同金属的活化、迁移明显不同。这表明,金属与氨基酸或其它有机物形成的易溶络合物,其稳定性不仅与金属、氨基酸等有机物的种类有关,而且还受温度的显著影响。 相似文献
4.
热液中铅、锌、银共生分异的热力学探讨 总被引：4，自引：0，他引：4
通过元素基本性质的对比以及热力学计算分析，探讨了热液中银、铅、锌的共生分异机制。在酸性至近中性条件下，氯配合物是它们在热液中的存在形式，其中锌氯配合物最稳定；在近中性到碱性条件下，硫氢配合物占主导地位，此时，银硫氢配合物相对最稳定。温度下降、[Cr]降低、pH升高及f(O2)降低，引起银、铅、锌配合物溶解度减小，发生沉淀分离；对于硫氢配合物，其稳定性主要受pH及还原硫浓度的影响。因此，配合物的不同存在形式以及配合物稳定性之间的差异，使得它们对热液条件的改变做出不同的响应，从而导致了热液中银、铅、锌在成矿过程中的共生分异。 相似文献
5.
综合采用地统计学、GIS和传统统计分析方法,研究了瑞安市耕作层土壤9种养分元素有效态含量空间变异特征及其影响因素。结果显示,研究区耕作层土壤碱解氮呈西高东低的分布趋势,速效钾、有效硼、有效锰、有效钼、有效铜和有效锌呈西低东高的分布趋势,有效磷呈东西高、中间低的分布趋势,有效铁分布均匀;研究区中西部耕作层有效硼较缺乏,东部碱解氮较缺乏,中部有效磷较缺乏,其他地区9种养分元素有效态含量均达到中等以上;半方差函数分析显示有效锰和有效铁为强空间相关性,碱解氮、速效钾、有效磷、有效钼、有效铜和有效锌为中等空间相关性,有效硼为弱空间相关性。研究认为,中性或是弱碱性、含盐量较高且阳离子较活跃的土壤环境有利于速效钾和有效硼富集,酸性或弱酸性和有机质含量较高的土壤有利于碱解氮和有效铁富集;速效钾、有效钼、有效硼、有效铜和有效锌含量的控制因素相似,主要受成土母质、土壤类型以及地形地貌等结构性因素和施肥、耕作等随机性因素的双重影响,而碱解氮、有效铁、有效磷和有效锰的含量分布主要受成土母质、土壤类型以及地形地貌等结构性因素的影响。 相似文献
6.
《International Journal of Mineral Processing》2005,76(3):163-172
The electrokinetics and flotation behavior of kaolinite have been investigated through flotation experiments, zeta potential measurements, and FTIR spectral analysis. These results have been explained based on crystal structure considerations and quantum mechanical calculations. It has been shown that the PZC of kaolinite is at pH 4.2. Kaolinite exhibits good floatability in weakly acidic solution with dodecyl amine (DDA) collector. The negative zeta potential of kaolinite increases with an increase in pH, and hence the adsorption of DDA on kaolinite increases. However, the flotation of kaolinite decreases with an increase in pH and an increase in DDA adsorption. This anomalous flotation behavior is rationalized based on crystal structure considerations and particle aggregation phenomena. It is considered that the silica (001) and the alumina (001¯) basal planes of kaolinite are negatively charged. From quantum chemistry calculations, the interaction between DDA and the (001) plane was found to be stronger than at the (001¯) alumina plane due to the difference in the structure at the (001) and (001¯) planes. The self-aggregation between (001¯) faces and the edge planes and the adsorption of DDA at the silica (001) plane make the kaolinite aggregates hydrophobic, and good floatability is achieved in acidic solution. In alkaline solution, the kaolinite particles are dispersed. In the presence of DDA, hydrophobic aggregation appears to occur in alkaline solution between the (001) planes due to adsorbed DDA, and thus the hydrophilic (001¯) faces are exposed and flotation is not achieved. 相似文献
7.
Humic acid adsorption onto the bacterial surface of Bacillus subtilis was measured with and without Cd, as a function of pH and humic–bacteria–Cd ratios. These experiments tested for the existence of ternary interactions in a bacteria–humic–metal system. We determine both the effects of humic acid on the bacterial adsorption of Cd, as well as the effects of the aqueous metal cation on the bacterial adsorption of humic acid. The presence of Cd does not affect the extent of humic acid adsorption onto the bacterial surface, indicating that there is no competition for sorption sites between humic acid and Cd under the experimental conditions, and that changes in the charging properties of the bacterial surface, as a result of the Cd adsorption, are not significant enough to affect humic acid adsorption.
The presence of humic acid does diminish Cd adsorption onto the bacterial surface, suggesting the presence of an aqueous Cd–humate complex under mid to high pH conditions. However, we also observe that the solubility of humic acid is unaffected by the presence of aqueous Cd. This apparently inconsistent behavior of an aqueous Cd–humate complex affecting Cd adsorption but not affecting humic acid solubility is not observed with simpler ionizable organic molecules. We propose that the solubility of humic acid is controlled by the solubility of a less soluble fraction of the acid. Cd forms an aqueous complex with the more soluble fraction of humic acid and there is no interdependence between the aqueous activities of the more and less soluble fractions. That is, the solubility of one humic acid fraction is unaffected by the presence of an aqueous Cd–humate complex involving another humic acid fraction. These experimental results constrain the relative importance of surface ternary and aqueous metal–humate complexes on the bacterial adsorption of both humic acid and metal cations. 相似文献
8.
A study on the adsorption characteristics of cadmium and zinc onto acidic and alkaline soils 总被引：1，自引：1，他引：0
Myoung-Jin Kim 《Environmental Earth Sciences》2014,72(10):3981-3990
The adsorption of cadmium (Cd) and zinc (Zn) with similar chemical properties is examined onto three soil samples: one is alkaline and the others are acidic. The distribution coefficient (K d) and the Freundlich constant (K F) for Zn are slightly higher than those for Cd, implying that the adsorption affinity of Zn is a little greater and less mobile. However, Cd and Zn usually show comparable results in the kinetic, isotherm, and envelope experiments. The adsorption of the heavy metals is relatively rapid and the reaction is almost completed within 15 min. The kinetics for both Cd and Zn are very well explained by the parabolic diffusion model. The maximum adsorption of the heavy metals is obtained at high pH, high temperature, and low ionic strength. The adsorption capacity on the alkaline soil is more significantly affected by the temperature as compared to the acidic soil. It is found that the adsorption affinity of the two heavy metals is mainly affected by the soil properties, such as pH, pHPZC, organic matter, and total carbon. It is also confirmed that the chemical properties of the heavy metals are important factors in their adsorption onto soil. The adsorption isotherms of Cd and Zn are well described in both Freundlich and Langmuir models at the usual pH (soil pH). Under acidic and alkaline pHs, however, only the Freundlich model describes the adsorption of both heavy metals satisfactorily. 相似文献
9.
10.
土壤对重金属离子的吸附容量明显受阴离子配位体的影响。本文通过试验探讨了Cl~(-),SOi_4~(2-)HCO_3~(-)阴离子在不同的pH值条件下,分别对土壤吸附铜的干扰规律。运用反求吸附参数法评价了不同阴离子对铜吸附量的干扰程度,论证了土壤与地下水之间元素迁移的规律。 相似文献
11.
On the basis of an experimental study and thermodynamic calculation, the mechanisms of paragenesis and separation of silver, lead and zinc in the hydrothermal system have been studied. At acidic to nearly neutral pH, their chloride complexes are stable, and among them the chloride complexes of zinc are most stable. And the sulfide complexes are the dominant species at nearly neutral to alkaline pH,while the sulfide complexes of silver are most stable. With decreasing temperature, [ Cl^-] ,fO2, and increasing pH, the solubilities of silver, lead and zinc will decrease, leading to their deposition and separation. For sulfide complexes, the concentrations of reduced sulfur and pH are two important factors affecting their stabilities. Complexes of different forms and stabilities respond to the variation of conditions to different extents, which gave rise to the paragenesis and separation of silver, lead and zinc in the whole ore-forming process of dissolution, transport and deposition. 相似文献
12.
The sorption of Np(V) and Np(IV) onto kaolinite has been studied in the absence and presence of humic acid (HA) in a series of batch equilibrium experiments under different experimental conditions: [Np]0: 1.0 × 10-6 or 1.0 × 10-5 M, [HA]0: 0 or 50 mg/L, I: 0.01 or 0.1 M NaClO4, solid to liquid ratio: 4 g/L, pH: 6–11, anaerobic or aerobic conditions, without or with carbonate. The results showed that the Np(V) sorption onto kaolinite is affected by solution pH, ionic strength, Np concentration, presence of carbonate and HA. In the absence of carbonate, the Np(V) uptake increased with pH up to ∼96% at pH 11. HA further increased the Np(V) sorption between pH 6 and 9 but decreased the Np(V) sorption between pH 9 and 11. In the presence of carbonate, the Np(V) sorption increased with pH and reached a maximum of 54% between pH 8.5 and 9. At higher pH values, the Np(V) sorption decreased due to the presence of dissolved neptunyl carbonate species with a higher negative charge that were not sorbed onto the kaolinite surface which is negatively charged in this pH range. HA again decreased the Np(V) uptake in the near-neutral to alkaline pH range due to formation of aqueous neptunyl humate complexes. The decrease of the initial Np(V) concentration from 1.0 × 10−5 M to 1.0 × 10−6 M led to a shift of the Np(V) adsorption edge to lower pH values. A higher ionic strength increased the Np(V) uptake onto kaolinite in the presence of carbonate but had no effect on Np(V) uptake in the absence of carbonate. 相似文献
13.
Inorganic minerals in mudstone are composed of clay minerals,carbonate and detrital minerals.Detrital minerals(such as quartz and feldspar)are mainly original deposit.However,clay minerals(kaolinite,illite,and chlorite)and carbonate(calcite and dolomite)are mostly diagenetic minerals.Furthermore,conversion of the four kinds of clay minerals are common.The formation of clay minerals and carbonate is controlled by temperature,pressure,p H,Eh and type of cations during diagenesis.Therefore mineral assemblage can indicate the characteristics and change of diagenetic environment.In addition to inorganic minerals,there are also organic matter of different sources and chemical properties in mudstone.Traditionally,it is considered that evolution of organic matter is controlled by thermal effect.Now studies show that inorganic and organic matter can interact with each other and form clay-organic complexes.This suggest that attention should be paid to the influence of diagenetic mineral assemblage and diagenetic environment on the evolution of organic matter* Samples of mudstone from 1500-4500m of the Palaeogene in the Dongying Depression,China,were collected to investigate the changes of mudstone diagenetic environment.XRD,thin section and SEM were used to detect diagenetic minerals and assemblage characteristics.Results showed that content of detrital minerals,which are floating in mud matrix or preserved as silt laminae,is basically unchanged from shallow to deep strata.Clay minerals which are gathered as argillaceous matrix or preserved as argillaceous laminae have growth and decline relation to carbonate which mainly appear as micropoikilitic ferriferous calcite and ferriferous dolomite.All these characteristics indicate that detrital minerals are exogenetic,whereas carbonate is diagenetic minerals.Based on the SEM analysis of the clay minerals,it was found that smectite present honeycomb and reticulate structure,while illite present filiform and schistose structure and there are growth and decline relationship between them.Nevertheless,hexagonal tabular and stratified kaolinite has the highest content from 2400m to3300m.Rosette and stratified chlorite shows increase trend when the burial depth is deeper than 3300m.These characteristics indicated that clay minerals are diagenetic minerals and there are conversions among the four types.Therefore form shallow to deep,three diagenetic mineral assemblage zones can be divided based on the characteristics of carbonate and clay minerals in mudstone.Namely,smectite+illite/smectite zone in the depth of 2000-2500m;kaolinite+illite/smectite zone in the depth of 2500-3300m and illite+chlorite+carbonate zone below 3300m.Previous studies showed that kaolinite is stable under acidic conditions,while other clay minerals and carbonate are stable under alkaline conditions.Hence according to mineral assemblages feature,it was inferred that diagenetic environment of mudstonehasundergonethechangeof alkaline-acid-alkaline.For the organic matter with different chemical properties in mudstone,the hydrocarbon generation will be different in the acidic and alkaline diagenetic environment even if the conditions of temperature and pressure are the same.Therefore,for hydrocarbon generation we should not only focus on thermal effect,but also pay more attention to the differences of diagenetic environment which have great significance for the understanding of hydrocarbon generation,hydrocarbon expulsion and reservoir formation in mudstone. 相似文献
14.
《Applied Geochemistry》2003,18(11):1723-1731
The mobility and bioavailability of heavy metals depends on the metal retention capacity of soil and also on the geochemical phases with which metals are associated. Laboratory batch experiments were carried out to study the sorption and distribution of Cd, Ni and Pb in 3 soils differing in their physicochemical properties from India: Oxyaquic Haplustalf (SL1), Typic Haplustalf (SL2) and Typic Haplustert (SL3). The heavy metal adsorption was studied by isotherms and the distribution coefficient (KD) for each metal was obtained from the linear regressions of the concentration of metal remaining in equilibrium solution and the amount adsorbed. In general, the sorption capacity for all the metals decreased in the order: SL3>SL2>SL1. Among metals, the sorption capacity in all the soils decreased in the order: Pb>>Ni>Cd. Distribution of sorbed metals at various equilibrating concentrations was studied by sequential extraction. Results showed significant differences in the distribution of metals in these soils. At higher additions (such as 200 μM l−1) most of the metals were extracted in their more mobile fractions, exchangeable and/or inorganic in contrast to their original partitioning in soils, where they were preferentially associated with the less mobile residual fraction. Largest percentages of metals extracted in the exchangeable fraction corresponded to those soil–metal systems with smaller KD values, e.g. Cd, Ni and Pb in SL1 and Cd and Ni in SL2. In neutral and alkaline soils (SL2, pH=7.1, and SL3, pH=8.6) Pb was predominantly extracted from the inorganic fractions and this corresponded to higher KD values for Pb in these soils. The predominance of metals associated with the exchangeable fraction together with low KD values indicates higher mobility of metals retained in the acidic soil (SL1, pH=5.2) compared with the others. 相似文献
15.
Lisbeth M. Ottosen Anne J. Pedersen Alexandra B. Ribeiro Henrik K. Hansen 《Engineering Geology》2005,77(3-4):317-329
Numerous studies have been conducted with electrochemical removal of heavy metals from spiked kaolinite. Meanwhile, when moving from kaolinite to real soils, new factors must be taken into account—factors influencing, e.g., the buffering capacity of the soil against acidification and the adsorption/desorption processes of the heavy metals. The present study gives some examples where it is necessary to use an enhancement solution to aid desorption of Cu, Zn and Pb during electrodialytic treatment. Dependent on the composition of the pollution, different choices can be made. In the case of a Cu-polluted calcareous soil, ammonia may be used as enhancement solution, due to the formation of charged complexes between ammonia and Cu. Thus, Cu is mobile at high pH when ammonia is added and Cu can be removed without dissolving the calcareous parts. Zn is also mobilized by ammonia, but to a lesser extent than Cu. In the case of Cu, Zn and Pb at the same time, alkaline ammonium citrate may be a solution. It was shown that this enhancement solution could mobilize these three pollutants, but optimization of concentration and pH of the ammonium citrate is still needed. When choosing a remediation scheme for electrochemical treatment of an actual industrially polluted soil, this scheme must be chosen on basis of characterization of soil and pollution combination. 相似文献
16.
H.G. Dill S. Altangerel J. Bulgamaa O. Hongor S. Khishigsuren Yo. Majigsuren S. Myagmarsuren C. Heunisch 《International Journal of Coal Geology》2004,60(2-4):197-236
The investigations involved geophysical, sedimentological, palynological, chemical and mineralogical studies, supported by field-based infrared spectrometry. The Baganuur Basin, Central Mongolia, is among the rift or pull-apart-basins, which subsided at the boundary between the Jurassic and the Lower Cretaceous in East Asia. During the Berriasian, peat accumulation began in the area under study in Central Mongolia. The palynoflora is akin to the Siberian palynological province. Based on the phytoclast assemblages and the ratios of total sulfur content to total organic content, marine transgressions into this intermontane basin may be ruled out. The coal interseam sediments were laid down prevalently under neutral to slightly alkaline conditions; only in some carbonaceous sediments, the pH of intrastratal solutions was lowered. Suboxic to anoxic conditions persisted during almost the entire Lower Cretaceous period in the Baganuur Basin. Based on the distribution of fining- and coarsening-upward sequences and the organic matter, the basin fill has been subdivided into seven depositional units (A: fluvial–swamp, B: fluvial–lacustrine, C: deltaic–fluvial, D: fluvial, E: fluvial–deltaic–lacustrine/floodplain (?), F: lacustrine–deltaic–swamp, G: swamp–fluvial). A conspicuous change in the fluvial–lacustrine regime and an increase in the sediment supply may be observed at the boundary between depositional units B and C. A strong uplift triggered the onset of an intensive delta sedimentation. Lithoclasts, heavy minerals (e.g., apatite, zircon, garnet, anatase, brookite, epidote, sphene, tourmaline) and phyllosilicates (e.g., kaolinite, smectite, mica, chlorite) attest to a mixing of detrital material. One provenance area was abundant in acidic plutonic rocks as shown by the granitic lithoclasts, the other in volcanic rocks, which produced the vitroclastic debris deposited as tephra fallout. Post-depositional alteration of the siliciclastic interseam sediments was favored by a distinctive facies association of transmissive and sealing horizons. It led to a re-deposition of Ca, U and Sr in the siliciclastics. Post-depositional alteration of the organic material converted it into lignite to subbituminous C coal. 相似文献
17.
Zhang Sheng Li Tongjin Wang LiankuiGuangzhou Institute of Geochemistry Chinese Academy of SciencesWushan Guangzhou 《《地质学报》英文版》1997,71(4):433-445
The Changkeng gold-silver deposits consist of a sediment-hosted, disseminated gold deposit and a replacement-type silver deposit. The mineralizations of gold and silver are zoned and closely related to the silicification of carbonate and clastic rocks, so that siliceous ores dominate in the deposit. The mineralizing temperature ranges mainly from 300 to 170℃, and K+, Na+, Ca2+, Mg2+, and Cl- are the major ions in the ore-forming fluid. Calculations of distribution of metal complexes show that gold is mainly transported by hydrosulphide complexes, but chloride complexes of silver, iron, lead, and zinc, which are transformed into hydroxyl and hydrosulphide complexes under neutral to weak-alkaline circumstances in the late stage, predominate in the ore-forming solutions. Water-rock interaction is confirmed to be the effective mechanism for the formation of silver ores by computer modelling of reaction of hydrothermal solution with carbonate rocks. The solubility analyses demonstrate that the precipitation 相似文献
18.
In this paper, some experimental studies on the modes of occurrence and the conditions of transport and precipitation of rare-earth elements (REE) in sea water have been made. The results show that the ions of REE and carbonate radicles can be combined into quite stable and soluble complexes in the medium of weak alkalinity. REE precipitation may result from the dissociation of REE complexes during the evolution of solutions from weakly alkaline to neutral or slightly acidic and in the presence of precipitants for REE, such as P, Ba, Ca, and Mg. That is why REE can be concentrated in carbonate formations. Experimental results also show that REE will be precipitated in the form of phosphate or F-carbonate in the presence of [PO4]3? and F? in the solution. Our experimental results are consistent with the geological characteristics of some REE deposits. 相似文献
19.
Y. H. Dawood H. H. Abd El-Naby A. A. Sharafeldin 《Journal of Geochemical Exploration》2004,81(1-3):15-27
El Atshan mining area, central Eastern Desert, represents one of the uranium occurrences related to alkaline volcanic rocks in Egypt. Based on the plot of total alkali elements versus silica, these rocks are classified as trachytes. The U and Eu anomalies appear to be derived from trachyte exposed to a long period of alteration and rock–fluid interaction. The trachyte has been subjected to two phases of alteration. The pronounced chemical changes include the mobility of Si, Na, Fe, U, Zn and REE and the immobility of Mg, Th, Hf, Ta and Sc. The late stage hydrothermal solutions caused the breakdown of the feldspars by losing sodium, potassium and partially silica and eventually formation of argillic alteration products, dissolution of iron-bearing sulphides, formation of iron-oxy hydroxides and corrosion of primary uranium minerals forming uranyl oxide hydrates. The acidic water percolating through the fractured trachyte rock leached not only available major or trace elements, but also REE. Eu originally incorporated in feldspars as Eu+2 has been oxidized to Eu+3 and subsequently leached away leaving a negative anomaly in the host rock. The leached U and Eu were then transported most probably as carbonate complexes. The second phase of alteration occurred at the near surface profile when the late stage hydrothermal fluids cool to the temperature of meteoric water and may have mixed with it, the pH of the fluids would shift to more alkaline values and at these conditions U and Eu were precipitated into the fracture system mainly by being adsorbed on the clay minerals and probably coprecipitated with iron oxy-hydroxides. 相似文献
20.
Fertilization and pH effects on processes and mechanisms controlling dissolved inorganic phosphorus in soils 总被引：5，自引：0，他引：5
We used of a set of mechanistic adsorption models (1-pK TPM, ion exchange and Nica-Donnan) within the framework of the component additive (CA) approach in an attempt to determine the effect of repeated massive application of inorganic P fertilizer on the processes and mechanisms controlling the concentration of dissolved inorganic phosphorus (DIP) in soils. We studied the surface layer of a Luvisol with markedly different total concentrations of inorganic P as the result of different P fertilizer history (i.e. massive or no application for 40 years). Soil pH was made to vary from acid to alkaline. Soil solutions were extracted with water and CaCl2 (0.01 M). The occurrence of montmorillonite led us to determine the binding properties of P and Ca ions for this clay mineral.Satisfactory results were obtained using generic values for model parameters and soil-specific ones, which were either determined directly by measurements or estimated from the literature. We showed that adsorption largely controlled the variations of DIP concentration and that, because of kinetic constrains, only little Ca-phosphates may be precipitated under alkaline conditions, particularly in the P fertilized treatment. The mineral-P pool initially present in both P treatments did not dissolve significantly during the course of the experiments. The adsorption of Ca ions onto soil minerals also promoted adsorption of P ions through electrostatic interactions. The intensity of the mechanism was high under neutral to alkaline conditions. Changes in DIP concentration as a function of these environmental variables can be related to changes in the contribution of the various soil minerals to P adsorption. The extra P adsorbed in the fertilized treatment compared with the control treatment was mainly adsorbed onto illite. This clay mineral was the major P-fixing constituent from neutral to alkaline pH conditions, because the repulsion interactions between deprotonated hydroxyl surface sites and P ions were sufficiently counterbalanced by Ca ions. The drastic increase of DIP observed at acid pH was due to the effect of the lower concentration of surface sites of Fe oxides and kaolinite.In addition to confirming the validity of our approach to model DIP concentrations in soils, the present investigation showed that adsorption was the predominant geochemical process even in the P fertilized soil, and that Ca ions can have an important promoting effect on P adsorption. However the influence of the dissolution of the mineral-P pool under field conditions remained questionable. 相似文献