Nonlinear dependence (on ionic strength, pH) of surface charge density and zeta potential in microchannel electrokinetic flow.

In this work, a numerical method is proposed to predict the electrokinetic phenomena and combined with an experimental study of the surface charge density (ρs) and zeta potential (ζ) behavior is investigated for borosilicate immersed in KCl and NaCl electrolytes, and for imogolite immersed in KCl, CaCl2, and MgCl2 electrolytes. Simulations and experiments of the electrokinetic flows with electrolyte solutions were performed to accurately determine the electric double layer (EDL), ζ, and ρs at various electrolyte concentrations and pH. The zeta potential was experimentally determined and numerically predicted by solving the coupled governing equations of mass, species, momentum, and electrical field iteratively. Our numerical prediction shows that ζ for borosilicate develops strong nonlinear behavior with the ion concentration following a power-law. Likewise, the ρs obeys a nonlinear behavior, decreasing as the concentration increases. Moreover, for imogolite, both ζ and the ρs behave nonlinearly with the pH. The EDL for borosilicate and imogolite becomes thinner as the electrolyte concentration and pH increase; this behavior is caused by increased ρs, resulting in the higher attraction of the free charges. The reported nonlinear behavior describes more accurately the interaction of the nanoparticle surface charge with the electrolytes and its effect on the electrolyte transport properties.

Study of Sorption Kinetics and Sorption-Desorption Models to Assess the Transport Mechanisms of 2,4-Dichlorophenoxyacetic Acid on Volcanic Soils.

The sorption behavior of 2,4-dichlorophenoxyacetic acid (2,4-D) in the abundant agricultural volcanic ash-derived soils (VADS) is not well understood despite being widely used throughout the world, causing effects to the environment and human health. The environmental behavior and risk assessment of groundwater pollution by pesticides can be evaluated through kinetic models. This study evaluated the sorption kinetics and 2,4-D sorption-desorption in ten VADS through batch sorption experiments. Differences in the sorption extent for the fast and slow phases was observed through the IPD model where 2,4-D sorption kinetics was controlled by external mass transfer and intra organic matter diffusion in Andisols (C1 ≠ 0). We confirmed from the spectroscopic analysis that the carboxylate group directly drives the interaction of 2,4-D on Andisol soil. The MLR model showed that IEP, FeDCB, and pH×Silt are important soil descriptors in the 2,4-D sorption in VADS. The Freundlich model accurately represented sorption equilibrium data in all cases (Kf values between 1.1 and 24.1 µg1-1/n mL1/ng-1) with comparatively higher sorption capacity on Andisols, where the highest hysteresis was observed in soils that presented the highest and lowest OC content (H close to 0).

Evaluation of zeolite, nanomagnetite, and nanomagnetite-zeolite composite materials as arsenic (V) adsorbents in hydroponic tomato cultures.

There is a growing interest in the use of adsorbent nanoparticles to mitigate the toxic effects of pollutants in natural matrices. However, due to their small size, nanoparticles have the potential to transport and disseminate contaminants adsorbed on their surfaces into environmental compartments with greater risk to human, animal, or plant health. This potential consequence of nanoparticle application remains largely unstudied. Here, we studied the application of three adsorbents, including zeolite (Z, micrometric size), nanomagnetite (Mt), and a nanomagnetite-zeolite composite (MtZ) intended to mediate arsenic toxicity in hydroponic tomato cultures. Adsorption studies showed an arsenate adsorption sequence of MtZ (6.2 mg g-1) ≥ Mt (4.7 mg g-1) â‰« Z (0.3 mg g-1). Tomatoes grown under the Mt condition demonstrated the lowest growth rate (4.2 cm), corresponding to a 45% decrease compared to the control (7.6 cm), as well as the highest oxidative stress level (0.024 µmol g-1) as indicated by malondialdehyde (MDA) concentration, almost twice the control (0.014 µg g-1). Tomatoes grown under MtZ conditions showed a 22% decreased growth (5.9 cm) but MDA levels (0.012 µmol g-1) were comparable to the control. Together, these results suggest that Mt at the nanometric size could obstruct channels in the plant and prevent absorption of water and nutrients. Anchoring nanomaterials in larger composites of micrometer size presents a promising alternative that would retain their super-adsorbent properties while avoiding toxicity due to nanometric size.

Mechanistic insights into simultaneous removal of copper, cadmium and arsenic from water by iron oxide-functionalized magnetic imogolite nanocomposites.

Imogolite and magnetic imogolite-Fe oxide nanocomposites (Imo-Fe50 and Imo-Fe25, at 50 and 25 % Fe loading (w/w), respectively) were synthesized and tested for the removal of aqueous copper (Cu), cadmium (Cd), and arsenic (As) pollutants. The materials were characterized by transmission electron microscopy, and specific surface area and isoelectric point measurements. The Fe-containing samples were additionally characterized by Mössbauer spectroscopy and vibrating-sample magnetometry. Significant differences were found in the morphological, electrophoretic, and magnetic characteristics between imogolite and the nanocomposites. The in-situ Fe-oxide precipitation process modified the active surface sites of the imogolite. The Fe-oxide, mainly magnetite, favored the contaminants' adsorption over the pristine imogolite. The adsorption kinetics of these pollutants were adequately described by the pseudo-second order and intraparticle diffusion models. The kinetic models showed that surface adsorption was more important than intraparticle diffusion in the removal of the pollutants by all the adsorbents. The Langmuir-Freundlich model described the experimental adsorption data, and both nanocomposites showed greater adsorption capacity than the imogolite. The adsorption of Cu and Cd was sensitive to cationic competition, showing a decrease of the adsorption capacity when the two cations coexisted, while their adsorption increased in the presence of arsenate.

Nicosulfuron sorption kinetics and sorption/desorption on volcanic ash-derived soils: Proposal of sorption and transport mechanisms.

Nicosulfuron sorption/desorption kinetics were studied through batch sorption studies in ten volcanic ash-derived Andisol and Ultisol soils with acidic pH and variable surface charge. Two different kinetic models were used to fit the experimental data: i) Models to establish kinetic parameters (Pseudo-First and Pseudo-Second-Order), and ii) Models to describe solute transport mechanisms of organic compounds on sorbents (Intraparticle Diffusion, Dimensionless Intraparticle, Boyd, and Two-Site Nonequilibrium). Sorption kinetic data best fit the pseudo-second-order model. Application of these models to describe solute transport suggests that underlying mechanisms are complex in all soils due to: i) surface sorption, with mass transfers controlling sorption kinetics across the boundary layer; and ii) pore diffusion (i.e. intraparticle diffusion into macropores and micropores). The Freundlich model explained equilibrium sorption data in all cases (R2 > 0.9979) with Kf values higher than those reported for different class of soils (6.85-16.08 µg1-1/n mL1/n  g-1). The hysteresis was significant in all studied soils. The lower sorption rate on Ultisols must be considered in regards to Nicosulfuron leaching potential.

Variable surface charge of humic acid-ferrihydrite composite: Influence of electrolytes on ciprofloxacin adsorption.

Antimicrobial compounds are found in a range of environments as pollutants. Here, we evaluated the influence of two common anions, NO3- and PO43-, on ciprofloxacin adsorption on humic acid/ferrihydrite composite (HA-DIG/Fh), synthetic ferrihydrite (Fh), and humic acid (HA-DIG) under controlled pH (7.0), ionic strength (0.1 M) and temperature (25 °C). All materials were characterized by isoelectric point (IEP), while the composite and the iron oxide were characterized by Mössbauer spectroscopy. Kinetic and isotherm adsorption studies were carried out using cyclic voltammetry (in KH2PO4) and square wave voltammetry (in KNO3). The application of kinetic models for both anions revealed Fh to fit to a pseudo second order model (R2 = 0.941); while HA-DIG (R2 = 0.950) and HA-DIG/Fh (R2 = 0.993) were fitted to pseudo first order models. The adsorption results showed a high dependency electrolyte, especially in Fh, where different shape curves (H-type in KNO3 and C-type in KH2PO4) and maximum experimental adsorbed amount Cm were observed. This finding is supported by the distinct IEP values and change in sign of surface charge between the two ions. Finally, results suggest that HA-DIG could be potentially used in environmental remediation to remove antibiotics from natural matrices, though the risk of antibiotic transportation increased with depth in the soil profile.

Biosynthesized CdS nanoparticles disturb E. coli growth through reactive oxygen production.

AIMS: E. coli is a widely known model organism for life science research, especially in modern bio-engineering and industrial microbiology. The goal of our current study is to understand the growth inhibitory mechanism of biosynthesized CdS nanoparticles on E. coli bacteria. MAIN METHODS: Characterization of Aspergillus foetidus mediated CdS nanoparticles has been confirmed by Zeta potential, AFM and HRTEM analyses. Furthermore, we investigated the contribution of reactive oxygen species (ROS) and subsequently lipid peroxidation on the growth of E. coli. FACS and fluorometric studies were used to know the ROS production upon CdS nanoparticle treatment. Lipid peroxidation measurement was studied by thiobarbituric acid (TBA) assay. KEY FINDINGS: The synthesized CdS nanoparticles are roughly spherical, poly-dispersed in nature and are in ~15 nm of size. Furthermore, our investigation confirmed that the cells treated with 200 µl of CdS nanoparticles produce about 50 % more ROS and about 5 times of lipid peroxidation over control cells. In addition, the number of E. coli colony survival and cell filamentation strongly depend on such lipid peroxidation caused by ROS, which actually produced due to the interaction with biosynthesized CdS nanoparticles in growth media. SIGNIFICANCE: The current research would be helpful for the mechanistic understanding of growth inhibition of E. coli by CdS nanoparticle. This may be useful for industrial applications of E. coli like bacteria.

Electrochemical method to study the environmental behavior of Glyphosate on volcanic soils: Proposal of adsorption-desorption and transport mechanisms.

Glyphosate is used extensively worldwide, but current evidence suggests detrimental effects on the environment, pollinators, and human health. Glyphosate adsorption kinetics and adsorption/desorption were studied through batch sorption experiments in ten typical volcanic ash-derived soils from Andisol and Ultisol orders. Two kinetic models were used to fit the experimental data: i. Models that allowed establishment of principally kinetic parameters and modeling of the adsorption process, and ii. Models described solute transport mechanisms commonly used for remediation purposes. Adsorption kinetic data were best fitted by the pseudo-second-order kinetic model and Two-Site Nonequilibrium model. These models suggest that mechanisms are complex due to rapid surface adsorption in ultisols with mass transfer controlling adsorption kinetics across the boundary layer, as indicated by the highhand lowt1/2values. High intraparticle diffusion into macropores and micropores was observed for Andisols. The Freundlich model accurately represented adsorption equilibrium data in all cases (R2 > 0.9580) with comparatively higher adsorption capacity on Andisols. Kf values (2.50-52.28 µg1-1/n mL1/n g-1) and hysteresis were significant in all studied soils. Taken together, these data suggest that Glyphosate may be adsorbed more on Andisol soils in comparison to Ultisols.

Surfactant properties of humic acids extracted from volcanic soils and their applicability in mineral flotation processes.

Surface Tension (ST) of water solutions of humic acids extracted from volcanic ash derived soils (soil humic acids, S-HA), were measured under controlled conditions of pH (13.0), temperature (25 °C) and ionic strength (NaOH 0.1M) to establish the Critical Micellar Concentration (CMC). All S-HA were characterized by elemental analysis, acid-base titration, Transmission Electronic Microscopy (TEM) micrographs, isoelectric point (IEP) and solid state 13C-NMR. After that, these humic acids were evaluated as potential biomaterials to be used in mineral flotation processes, where a series of experiments were conducted at different S-HA and molybdenite ratio (from 0.2 to 50 g ton-1) establishing the IEP of all resultant materials. The use of solid state 13C-NMR enabled the following sequence of intensity distribution areas of S-HA to be established: O/N Alkyl>Alkyl C>Aromatic C>Carboxyl. The experimental values of ST and the calculated CMC (ranging from 0.8 to 3.3 g L-1) revealed that for S-HA no relationship between the abundance groups and their behavior as surfactant materials was observed. In relation with IEP determined for all materials, the highest surface charge, which can be useful for flotation processes, was obtained with 0.2 g of S-HA per ton of molybdenite. Additionally, TEM studies confirm the formation of pseudoaggregates for all the S-HA considered. Finally, the S-HA could be considered as an alternative to chemical products and commercial humic acids materials in mineral flotation processes.

Distribution of contaminant trace metals inadvertently provided by phosphorus fertilisers: movement, chemical fractions and mass balances in contrasting acidic soils.

The frequent use of phosphorus (P) fertilisers accompanied by nitrogen and potassium sources may lead to a serious long-term environmental issue because of the presence of potentially hazardous trace metals (TM) in P fertilisers and unknown effects on the TM chemical fractions in agricultural soils. A 16-month-long column experiment was conducted to investigate the mobility and chemical forms of Cd, Cu, Cr, Ni, and Zn introduced into a Mollisol and an Andisol through surface incorporation (0-2 cm) of triple superphosphate (TSP) fertiliser. The effects of urea and potassium chloride (KCl) applications were investigated as well. After 15 cycles of 300-mm irrigation, TSP addition increased the 4 M HNO3 extractable TM concentration in the upper (0-5 cm) section of soils. Beyond this depth, metals showed no significant mobility, with minimal leaching losses (< 1.9%, 25-cm depth). The TM chemical forms in the 0-5 cm section were significantly (p < 0.01) affected by the soil type and fertilisers addition. Cadmium, Ni, and Zn were the elements which appeared in a larger proportion (up to 30%) in the most labile fraction (KNO3 extractable) in fertilised soils. The impact of urea depended on the nitrification-related changes in soil pH, while fertilisation with KCl tended to increase the KNO3 fraction of most metals probably due to K+ exchange reactions. Chromium remained minimally affected by the urea and KCl applications since this contaminant is strongly bound to the less labile solid phases. The low mobility of TM was governed mainly by their interaction with the solid phases rather than by their speciation at soil pH. The mass balance showed that the geochemical processes underwent in time by the P fertiliser increased the amount of TM extracted by the chemical fractionation scheme, therefore the reaction period of TSP with soil particles should be taken into account for evaluating TM availability. Long-term soil fertilisation could inadvertently contribute to an increased concentration and availability of these P fertilisers-born contaminants in the cultivated layer of acidic soils.

Spectroscopic and Electrochemical Studies of Imogolite and Fe-Modified Imogolite Nanotubes.

Carbon nanotubes and other forms of carbon nanoparticles, as well as metal nanoparticles have been widely used in film electrochemistry because they allow for the immobilization of larger amounts of catalyst (either biological or inorganic) on the top of the modified electrodes. Nevertheless, those nanoparticles present high costs of synthesis and of separation and purification that hamper their employment. On the other hand, imogolites (Im), with the general formula (OH)3Al2O3SiOH, are naturally-occurring nanomaterials, which can be obtained from glassy volcanic ash soils and can also be synthesized at mild conditions. In this research paper, we characterize through spectroscopic techniques (i.e., fourier transform infrared spectroscopy (FTIR) spectroscopy, powder X-ray diffraction (XRD) and transmission electron microscopy (TEM)) synthetized Im and Fe-modified imogolite (Im(Fe)). Moreover, the Im and Im(Fe) were physically adsorbed on the top of a graphite electrode (GE) and were characterized electrochemically in the potential region ranging from -0.8 to 0.8 V vs. the saturated calomel electrode (SCE). When the film of the Im or of the Im(Fe) was present on the top of the electrode, the intensity of the charging/discharging current increased two-fold, but no redox activity in the absence of O2 could be appreciated. To show that Im and Im(Fe) could be used as support for catalysts, iron phthalocyanine (FePc) was adsorbed on the top of the Im or Im(Fe) film, and the electrocatalytic activity towards the O2 reduction was measured. In the presence of the Im, the measured electrocatalytic current for O2 reduction increased 30%, and the overpotential drastically decreased by almost 100 mV, proving that the Im can act as a good support for the electrocatalysts.

Effect of cations in the background electrolyte on the adsorption kinetics of copper and cadmium and the isoelectric point of imogolite.

Modification of surface charge and changes in the isoelectric point (IEP) of synthetic imogolite were studied for various cations in the background electrolyte (K(+), NH4(+), Mg(2+), and Ca(2+)). From the electrophoretic mobility data, it was established that the K(+) (KCl) concentration does not affect the IEP of imogolite; therefore, KCl is a suitable background electrolyte. In terms of the magnitude of changes in the IEP and surface charge, the cations may be ranked in the following order: Mg(2+)≈Ca(2+)>>NH4(+)>>K(+). Four different kinetic models were used to evaluate the influence of Mg(2+), Ca(2+), NH4(+), and K(+) on the adsorption of Cd and Cu on synthetic imogolite. When adsorption occurs in the presence of cations with the exception of K(+), the kinetics of the process is well described by the pseudo-first order model. On the other hand, when adsorption is conducted in the presence of K(+), the adsorption kinetics is well described by the pseudo-second order, Elovich, and Weber-Morris models. From the surface charge measurements, the affinity between imogolite and the cations and their effect on the adsorption of trace elements, namely Cu and Cd, were established.

Capture and accumulation of perchlorate in lettuce. Effect of genotype, temperature, perchlorate concentration, and competition with anions.

Various studies have evaluated the accumulation of ClO4(-) in lettuce (Lactuca sativa), but very few have dealt with the variables that can interfere with its capture. The present study evaluates the transfer of ClO4(-) in two L. sativa varieties: butter head (L. sativa var. capitata) and cos lettuce (L. sativa var. crispa) under hydroponic conditions. The ClO4(-) concentrations used correspond to levels (1 and 2mgL(-1)), measured in irrigation water in the Iquique region in the north of Chile. Results indicate that the capture of ClO4(-) is dependent on its concentration, lettuce genotype, and temperature. The butter head variety accumulates the highest perchlorate concentrations. Anion competition involving NO3(-) (16 and 48mM), Cl(-) (23 and 56mM), and SO4(2-) (10 and 20mM) was evaluated, being NO3(-) (48mM), the most significant competition reducing the concentration of ClO4(-) in tissues of L. sativa varieties.

Effect of aluminum on antioxidant activity and phenolic compounds content in in vitro cultured blueberries / Efectos de aluminio en la capacidad antioxidante y en el contenido de compuestos fenólicos en plántulas de arándano cultivadas in vitro

Blueberry is a popular natural food product consumed worldwide. Acid soils are found throughout the world. A significant problem of acid soils is the active aluminum content, which may result toxic to plant. The present study was undertaken to assess the toxicities of Al for Blueberry (Vaccinium corymbosum L.) cultivated in vitro and treated with 100 and 200 uM Al. The effects of Al concentration on malondialdehyde (MDA) content, antioxidant activity and phenolic compounds of blueberry after 7, 14 and 21 days of treatment were established. The analysis of the MDA accumulated in the tissues of the blueberry seedlings indicates that Al concentration increases the damage caused by lipid peroxidation, for both treatments, after 14 days. The highest antioxidant activity in the extracts was observed at 200 uM Al after 14 days of treatment, being chlorogenic and ellagic acids the most significant metabolites involved in the antioxidant properties. Then, the content of Al in soil could be modulate the content of bioactive compounds in blueberry plants.

El Arándano es un popular alimento natural consumido en todo el mundo. Los suelos ácidos se encuentran en todo el mundo. Un problema significativo de suelos ácidos es el contenido de aluminio activo, que puede resultar tóxico para la planta. Este estudio se realizó para evaluar la toxicidad del aluminio en plantas de arandano, cultivadas in vitro y tratadas con 100 y 200 mM de Al. Se establecieron los del aluminio en el contenido de malodialdehido (MDA), capacidad antioxidante y contenido de compuestos fenolicos en plantulas de arandano luego de 7, 14 y 21 dias de tratamiento. El análisis del MDA acumulado en los tejidos de las plantulas de arándanos indica que la concentración de Al aumenta el daño causado medido como peroxidación de lípidos, para ambos tratamientos, después de 14 días. La actividad antioxidante más alta de los extractos se obseva a 200 mM de Al después de 14 días de tratamiento, siendo los ácidos clorogénico y elágico los metabolitos más importantes que participan en las propiedades antioxidantes. Entonces, el contenido de Al en el suelo podría modular el contenido de compuestos bioactivos en plantas de arándanos, alterando sus propiedades medicinales.

Sorption kinetics of diuron on volcanic ash derived soils.

Diuron sorption kinetic was studied in Andisols, Inceptisol and Ultisols soils in view of their distinctive physical and chemical properties: acidic pH and variable surface charge. Two types of kinetic models were used to fit the experimental dates: those that allow to establish principal kinetic parameters and modeling of sorption process (pseudo-first-order, pseudo-second-order), and some ones frequently used to describe solute transport mechanisms of organic compounds on different sorbents intended for remediation purposes (Elovich equation, intraparticle diffusion, Boyd, and two-site nonequilibrium models). The best fit was obtained with the pseudo-second-order model. The rate constant and the initial rate constant values obtained through this model demonstrated the behavior of Diuron in each soil, in Andisols were observed the highest values for both parameters. The application of the models to describe solute transport mechanisms allowed establishing that in all soils the mass transfer controls the sorption kinetic across the boundary layer and intraparticle diffusion into macropores and micropores. The slowest sorption rate was observed on Ultisols, behavior which must be taken into account when the leaching potential of Diuron is considered.

Kinetic and Surface Study of Single-Walled Aluminosilicate Nanotubes and Their Precursors.

The structural and surface changes undergone by the different precursors that are produced during the synthesis of imogolite are reported. The surface changes that occur during the synthesis of imogolite were determined by electrophoretic migration (EM) measurements, which enabled the identification of the time at which the critical precursor of the nanoparticles was generated. A critical parameter for understanding the evolution of these precursors is the isoelectric point (IEP), of which variation revealed that the precursors modify the number of active ≡Al-OH and ≡Si-OH sites during the formation of imogolite. We also found that the IEP is displaced to a higher pH level as a consequence of the surface differentiation that occurs during the synthesis. At the same time, we established that the pH of the reaction (pHrx) decreases with the evolution and condensation of the precursors during aging. Integration of all of the obtained results related to the structural and surface properties allows an overall understanding of the different processes that occur and the products that are formed during the synthesis of imogolite.

Metsulfuron-methyl sorption/desorption behavior on volcanic ash-derived soils. effect of phosphate and pH.

Metsulfuron-methyl sorption/desorption behavior was studied through batch sorption experiments in three typical volcanic ash-derived soils belonging to Andisol and Ultisol orders. Their distinctive physical and chemical properties are acidic pH and variable surface charge. Organic matter content and mineral composition affected in different ways sorption of metsulfuron-methyl (K(OC) ranging from 113 to 646 mL g(-1)): organic matter and iron and aluminum oxides mainly through hydrophilic rather than hydrophobic interactions in Andisols, and Kaolinite group minerals, as major constituents of Ultisols, and iron and aluminum oxides only through hydrophilic interactions. The Freundlich model described metsulfuron-methyl behavior in all cases (R(2) > 0.992). K(f) values (3.1-14.4 microg(1-1/n) mL(1/n) g(-1)) were higher than those reported for different class of soils including some with variable charge. Hysteresis was more significant in Ultisols. A strong influence of pH and phosphate was established for both kinds of soil, intensive soil fertilization and liming being the most probable scenario for leaching of metsulfuron-methyl, particularly in Ultisols.

Modeling the sorption kinetic of metsulfuron-methyl on Andisols and Ultisols volcanic ash-derived soils: kinetics parameters and solute transport mechanisms.

Metsulfuron-methyl sorption kinetic was studied in Andisol and Ultisol soils in view of their distinctive physical and chemical properties: acidic pH and variable surface charge. Different kinetic models were applied to the experimental results. The pseudo-second-order model fitted sorption kinetics data better than the pseudo-first-order model. The rate constant and the initial rate constant values obtained through this model demonstrated the different behavior of metsulfuron-methyl in both kinds of soils, both parameters being the highest for Andisol. The application of Elovich equation, intraparticle diffusion model and a two-site nonequilibrium model (TSNE) allowed to conclude that: (i) the high organic matter content is the governing factor for Andisols where mass transfer across the boundary layer, and in a lesser degree, intraparticle diffusion were the two processes controlling sorption kinetic and (ii) the mineral composition was more relevant in Ultisols where rate was controlled almost exclusively by intraparticle diffusion into macropores and micropores. The slower sorption rate on Ultisols, the mechanism involved and the lower sorption capacity of this kind of soils must be taken into account to assess leaching behavior of this herbicide.

Disposal of domestic sludge and sludge ash on volcanic soils.

Column leaching experiments were conducted to test the ability of Chilean volcanic soils in retaining the mineral constituents and metals in sewage sludge and sludge ash that were incorporated into the soils. Small or negligible amounts of the total content of Pb, Fe, Cr, Mn, Cd, and Zn (0 to <2%), and more significant amounts of mineral constituents such as Na (7-9%), Ca (7-13%), PO4 (4-10%), and SO4 (39-46%) in the sludge and sludge ash were readily soluble. When they were incorporated on the surface layer of the soils and leached with 12 pore volumes of water over a 3 month period of time, less than 0.1% of the total amount of heavy metals and PO4 in the sludge and sludge ash were collected in the drainage water. Cation exchange selectivity, specific anion adsorption and solubility are the processes that cause the reduction of leaching. The volcanic soils were capable of retaining the mineral constituents, P, and metals in applied sewage sludge and sludge ash and gradually released them as nutrients for plant growth.