Personal Research Database

Full Text: J Env Qua22, 186.pdf

Abstract: Laboratory studies were conducted to determine the effects of waste-activated carbon (WAC), digested municipal sewage sludge (DMS), and animal manure (AM) on the sorption and leaching of alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl)acetanilide] in a Plainfield sandy soil (Typic Udipsamment). A total of 7500 mL of simulated rain water was applied to soil columns under three flow regimes with or without the waste amendments. The WAC most effectively reduced the mobility of alachlor, DMS was superior to AM. Amounts of alachlor recovered in the leachates, which ranged from <0.1% (2.1 t C ha-1 of WAC amended soil) to 74% (unamended soil) of that applied, depended upon the C loading rate of the wastes and upon the source of C-containing species. The dissipation of alachlor from soil was greater when soil was amended with DMS and AM than when amended with WAC. Sorption of alachlor, which was determined by batch equilibration, was generally inversely related to its leaching in the amended soil, this observation suggested that sorption by soil organic matter controlled the mobility of alachlor. Application of C-rich wastes to sandy coarse-textured soils may be useful for reducing pesticide leaching to groundwater.

Keywords: Activated Carbon, Animal Manure, Biodegradation, Carbon, Degradation, Dissipation, DMS, Flow, Groundwater, Insecticides, Leaching, Loading, Manure, Matter, Metolachlor, Mobility, Observation, Organic, Organic Matter, Organic-Matter, Pesticide, Rain, Residues, Sandy Soil, Sewage, Sewage Sludge, Sludge, Soil, Soil Organic Matter, Soils, Sorption, Source, Waste, Wastes, Water

Roy, W.R., Krapac, I.G. and Steele, J.D. (1993), Soil processes and chemical-transport: Sorption of cadmium and lead by clays from municipal incinerator ash water suspensions. Journal of Environmental Quality, 22 (3), 537-543.

Full Text: J Env Qua23, 537.pdf

Abstract: The effect of Cl complexation in extracts of a flue gas-scrubber incinerator fly ash sample on the sorption of Cd and Pb by kaolinite and illite was investigated using batch-sorption methods. In the pH range of 5 to 9, Cl complexation may reduce sorption and thus increase the mobility of these metals. When an ash-water suspension was acidified to pH 6.85, the dissolution of Cl and Ca essentially eliminated Cd sorption because of complexation and cationic competition. Cadmium would be considered as either mobile or very mobile under these conditions. Lead was not soluble in the pH-6.85 suspension. At pH 12, the approximate pH of water in contact with flue gas-scrubber fly ash, Cd was essentially insoluble and Pb occurred as anionic Pb hydroxide. Anionic Pb was sorbed by the two clays, and the extent of sorption was not influenced by Cl or carbonate complexation. Sorption constants, derived from isotherms, suggested that Pb would be relatively immobile in saturated soil-water systems. The recent concern that highly alkaline, flue gas-scrubber fly ash may release environmentally significant concentrations of mobile Pb when placed in an ash-disposal site with a soil liner should be reevaluated in light of this study.

Keywords: Chloride, Metals

? Schulte, A. and Beese, F. (1994), Isotherms of cadmium sorption density. Journal of Environmental Quality, 23 (4), 712-718.

Full Text: J Env Qua23, 712.pdf

Abstract: To study Cd sorption, 16 soil samples of different chemical soil reactions were taken and analyzed for their physical and chemical properties. Adsorption of ethylene glycol monoethyl ether (EGME) and N₂ were determined to establish the specific surface area of the soils. The sorption of Cd was modeled on a per-mass basis using the Langmuir and Freundlich equations as well as per-surface area basis. Traditional sorption isotherms reveal the relation between the amount of Cd sorbed and the Cd concentration in the soil solution only for the soil under study and can therefore not be applied, or can be applied only with restrictions, to other soils. To meet the aim of modeling Cd sorption and mobility for other soils or locations differing greatly in their properties, we attempted to establish a generalizing sorption isotherm for soils of entirely different composition of the solid phase. On the basis of characteristic values the 16 soil samples taken were grouped into three different reaction types (aluminum-hydroxide, silicate, and carbonate-buffer range). The generalizing Cd sorption density isotherms for these different soil groups introduced in the following provide a useful mathematical model for the quantity-intensity relation of Cd in soils that differ greatly in their specific surface area and their composition.

Keywords: Adsorption, Soils, Water

Bierman, P.M. and Rosen, C.J. (1994), Phosphate and trace metal availability from sewage-sludge incinerator ash. Journal of Environmental Quality, 23 (4), 822-830.

Full Text: J Env Qua23, 822.pdf

Abstract: Incineration is practiced to reduce sewage sludge volume, but disposal of the resulting ash remains an important waste-management problem. The objectives of a field study conducted from 1987 to 1990 were to evaluate sewage-sludge-incinerator ash as a P fertilizer, determine trace metal availability, and assess the liming potential of the ash. The soil was an Estherville sandy loam (sandy, mixed, mesic Typic Hapludoll) with an initial pH of 5.7. Treatments compared P rates of 35, 70, and 140 kg ha^-1 yr^-1 from triple-superphosphate fertilizer with equivalent ash rates based on citrate-soluble (available) P. A control receiving no P application was included. Field corn (Zea mays L.) was grown the first 3 yr and sweet corn was grown in 1990. Limited effects on growth occurred the first 2 yr, but in 1989 and 1990 both ash and phosphate fertilizer significantly increased yield. Yield response to ash was equivalent to phosphate fertilizer for 1989 field corn, but significantly less for sweet corn in 1990. Ash and phosphate fertilizer both increased tissue P concentrations, but phosphate fertilizer was the more effective P source. Olsen’s soil P extractant provided a more useful measure of plant available P than Bray P-1 for ash-amended soil. Ash increased diethylenetriaminepentaacetic-acid (DTPA) extractable Cu, Zn, and Cd in the theta-to 15-cm soil depth and slightly buffered soil pH. Concentrations of Cu and Zn in plant tissue were consistently higher, and Mn consistently lower, with ash than with phosphate fertilizer. In 1990, ash also significantly increased tissue Cd and Mo in sweet corn. Tissue trace metal concentrations were not in the range of anticipated phytotoxicity or animal health problems.

Salingar, Y., Sparks, D.L., Ghodrati, M. and Hendricks, G.J. (1994), Kinetics of ion removal from an iron-rich industrial coproduct: I. Chloride. Journal of Environmental Quality, 23 (6), 1194-1200.

Full Text: J Env Qua23, 1194.pdf

Abstract: An industrial TiO₂ extraction process results in a Fe-rich material (IRM) that contains substantial chlorides. Recent investigations showed that washed IRM may serve as a soil amendment for agricultural use. Yet, washing processes at the industrial production facility are currently problematic and costly, and it is essential to devise effective procedures for CI removal. This study was conducted to determine the mechanism of CI retention, and to ascertain whether the rate of Cl removal was governed by time-dependent surface-chemical kinetics or diffusion (transport)-controlled kinetics. The IRM samples we used throughout the study were homogenous. It was physicochemically characterized and concentrations of heavy metals were determined. The IRM batch studies revealed negative CI adsorption, even though its point of zero charge was 8.3. Column studies showed that 92% of the CI was removed with the first pore volume. Additionally, the salt removal decreased the electrolyte concentration, caused dispersion, and, ultimately, lowered the hydraulic conductivity. Stirred-how kinetic studies established that Cl leaching was a function only of the total volume that flowed through the chamber, and that no chemical kinetics were involved.

Keywords: Stirred-Flow Chamber, Adsorption-Desorption, Soil Columns, Transport, Equation, Exchange

Salingar, Y., Sparks, D.L. and Pesek, J.D. (1994), Kinetics of ion removal from an iron-rich industrial coproduct: II. Sulfate. Journal of Environmental Quality, 23 (6), 1201-1205.

Full Text: J Env Qua23, 1201.pdf

Abstract: An iron-rich material (IRM) contained copious quantities of salts, including Cl and SO₄ A previous study on Cl removal hypothesized that SO₄ played a major role in the chemistry of the IRM. Therefore, this study investigated the kinetics of SO₄ removal from the IRM, which had a point of zero charge similar to those of some tropical soils. Stirred-how (SF) and column studies showed that SO₄ removal was a time-dependent chemical reaction(s). The SF technique facilitated modeling of the chemical kinetics of SO₄ removal by providing a uniformly mixed system. The SO₄ removal mechanism from the IRM to the ambient solution, in the SF system, was a zero-order oxidation-dissolution reaction of the Fe-sulfide present as a minor constituent in the IRM. The computed value of the rate-constant was 0.043 mol min^-1. In the column studies, the newly dissolved SO₄ was present in the effluent, and was adsorbed on the IRM through a Ligand (OH^-) exchange mechanism. Calcium hydroxide dissolution, together with the SO₄ adsorption, resulted in a pH increase with pore-volume.

Keywords: Pyrite Oxidation, Charge Relationships, Surface-Charge, 2 Spodosols, Adsorption, Desorption, Soil, Sorption, pH, Temperature

Salingar, Y., Sparks, D.L. and Pesek, J.D. (1994), Kinetics of ion removal from an iron-rich industrial coproduct: III. Manganese and chromium. Journal of Environmental Quality, 23 (6), 1205-1211.

Full Text: J Env Qua23, 1205.pdf

Abstract: An iron-rich material (IRM) contained the potential soil and water pollutants Mn and Cr. Therefore, to assess the feasibility of using the IRM in agricultural and nonagricultural settings, this study was conducted to determine the processes and kinetics of Mn and Cr (total soluble metals) retention and removal from the IRM. This was accomplished by employing adsorption isotherms, column studies and the stirred-how (SF) kinetic technique. Manganese adsorption conformed to the Langmuir equation and Cr adsorption was described by the Freundlich equation. The kinetic studies showed that indigenous Mn salts were depleted instantaneously via a volume-dependent process. Both Mn and Cr in the IRM became solubilized while being processed at the industrial plant. But, unlike Mn, Cr was readsorbed by the IRM after the initial solubilization. This fraction of the Cr was desorbed rapidly, conforming to first-order kinetics and yielding a rate-constant of 0.56 min^-1. After the rapid removal of some of the Mn and Cr, a steady-state with wodginite may have governed Mn removal and chromite may have controlled the Cr concentration, through zero-order dissolution reactions. Both column and SF studies showed that the proportion of total soluble (dischargeable) Mn and Cr was small.

Brixie, J.M. and Boyd, S.A. (1994), Treatment of contaminated soils with organoclays to reduce leachable pentachlorophenol. Journal of Environmental Quality, 23 (6), 1283-1290.

Full Text: J Env Qua23, 1283.pdf

Abstract: The toxicity characteristic leaching procedure (TCLP, method 1311) (USEPA, 1990) was used to evaluate the effectiveness of nine organoclays in reducing the leachability of pentachlorophenol (PCP) from three highly contaminated (3000-5000 mg kg^-1) soils from wood treatment facilities. The soils differed in their PCP, oil and grease, and organic C contents. The organoclays were smectite exchanged with quaternary ammonium cations of the form [(CH₃)₃NR](+) or [(CH₃)₂NR₂](+) where R is an aliphatic or aromatic hydrocarbon. A cement-based solidification agent (Sorbond) was also added to the soil to evaluate its effects on the leachability of PCP. Organoclays with large (> C-10) aliphatic R groups (organophilic organoclays) were compared with those with small aromatic or aliphatic groups (adsorptive organoclays). The adsorptive organoclays were much less effective than the organophilic clays in reducing PCP levels in the TCLP leachate. The organophilic clays dramatically reduced the leachability of PCP from all of the soils. The most effective clay tested was the dimethyldicocoammonium smectite; a 20% addition of this organoclay to the soil resulted in leachable PCP levels below the detection limit (0.2 mg L^-1). The addition of Sorbond to the soil increased both the pH (from 4.95 to 12.00) and the PCP concentrations (from 6.8 to 100.8 mg L^-1) in the leachate. However, when Sorbond was added with an organophilic clay, the PCP concentration was decreased below detection limits despite the increase in pH. These results demonstrate the potential effectiveness of organoclays for reducing the leaching of PCP from highly contaminated soils.

Keywords: Organic-Compounds, Sorption, Clays, Water, Adsorption, Smectite, Stabilization

? Holm, P.E., Christensen, T.H., Tjell, J.C. and Mcgrath, S.P. (1995), Speciation of cadmium and zinc with application to soil solutions. Journal of Environmental Quality, 24 (1), 183-190.

Full Text: J Env Qua24, 183.pdf

Abstract: A two-part method has been developed for determination of Cd and Zn species In 50-mL soil solution samples containing low concentrations of Cd and Zn (1-10 g Cd L^-1 and 50-1000 g Zn L^-1). The method uses two cation exchange resins (Amberlite CG 120 and Chelex 100) in a batch-column-batch procedure and relies on analytical determinations of Cd and Zn by graphite furnace atomic absorption spectrophotometry. The first part (batch) of the method allows determination of free divalent Cd²⁺ and Zn²⁺. This part is experimentally sensitive to cation concentrations and ionic strength and these parameters should be controlled during the experimental procedures. However, it is shown that Cd and Zn concentrations and pH do not influence the method. Speciations performed on samples containing chloride and sulfate were in accordance with theoretical calculations. The second part (column-batch) of the method operationally separates the complexed fraction into labile complexes, slowly labile complexes, and stable complexes. Chloro complexes were identified as labile complexes, while EDTA complexes were identified as stable complexes. The method works well with relatively small volumes of sample solutions and at low metal concentrations and may be useful in characterization of Cd and Zn in soil solutions.

Keywords: Solid-Waste Leachates

Bierman, P.M., Rosen, C.J., Bloom, P.R. and Nater, E.A. (1995), Soil solution chemistry of sewage-sludge incinerator ash and phosphate fertilizer amended soil. Journal of Environmental Quality, 24 (2), 279-285.

Full Text: J Env Qua24, 279.pdf

Abstract: The chemical composition of the soil solution provides useful information on the feasibility of amending agricultural land with municipal and industrial waste, because the soil solution is the medium for most soil chemical reactions, the mobile phase in soils, and the medium for mineral absorption by plant roots. The soil solutions studied in this research were from plots in a 4-yr field experiment conducted to evaluate the effects of the trace metals and P in sewage-sludge incinerator ash. Treatments compared ash with equivalent P rates from triple-superphosphate fertilizer and a control receiving no P application. Ash and phosphate fertilizer were applied annually at rates of 35, 70, and 140 kg citrate-soluble P ha^-1. Cumulative ash applications during 4 yr amounted to 3.6, 7.2, and 14.4 Mg ash ha^-1. Soil solutions were obtained by centrifugation-immiscible liquid displacement using a fluorocarbon displacing agent. Following chemical analysis, a chemical speciation model was used to determine possible solubility-controlling minerals for trace metals and P, and correlations between solution composition and plant uptake were analyzed. Ash increased soil solution pH, Cd, and Zn, but had no significant effect on solution concentrations of other trace metals. Ash increased soil solution P and S, but P increases were less than those from equivalent citrate-soluble P rates of phosphate fertilizer. Soil solution Ba appeared to be in equilibrium with barite (BaSO₄). Solubility data did not indicate that any discrete mineral phases controlled Cd, Zn, Cu, Ni, Pb, or P solubility. Soil solution P concentration was strongly correlated (r = 0.92) with P accumulation in sweet corn (Zea mays L.) plants, but solution trace metal concentrations were either weakly correlated (r = 0.49 for Zn and 0.36 for Cd) or not significantly correlated (r = 0.09 for Ni and - 0.25 for Cu) with plant accumulation.

Keywords: Immiscible Displacement, Trace, Ammonia, Nitrate, Waters, Liquid

? Yu, Y.S., Bailey, G.W. and Jin, X.C. (1996), Application of a lumped, nonlinear kinetics model to metal sorption on humic substances. Journal of Environmental Quality, 25 (3), 552-561.

Full Text: J Env Qua25, 552.pdf

Abstract: Exposure assessment models are needed to predict the sorption behavior of metal ions with humic substances. To address this need, a lumped parameter nonlinear kinetics model based on the Langmuir-Hinshelwood kinetic model-dC/dt = k(1)C/(1 + k(o)C)-is introduced and evaluated. The model was applied to a mixture of seven metal ions-Cr(III), Pb(II), Cu(II), Cd(II), Co(II), Ag(I), and Li(I)-reacted with three individual humic substances. The lumped parameter model employs a dimensional analysis technique (i.e., uses dimensionless parameters), Laplace transforms, gamma functions, and gamma distributions to produce analytical solutions for the kinetic equation of metal ion sorption to humic substances. During the initial reaction period, the most reactive species-Cr(III) and Pb(II)-dominated the lump parameter value, and the mixture behaved like a first-order reaction. At longer periods, the lump followed a second-order decay if there were less reactive species involved. The lumped parameter model provides valuable information about the overall kinetics behavior of metal ion mixtures with humic substances and could serve as a simulation tool to investigate the transport of metal ions in and out of landfill sites and the transport/retardation of metals in contaminated soils and aquifers.

Keywords: Mixtures, Soils

? Yin, Y.J., Allen, H.E., Li, Y.M., Huang, C.P. and Sanders, P.F. (1996), Adsorption of mercury(II) by soil: Effects of pH, chloride, and organic matter. Journal of Environmental Quality, 25 (4), 837-844.

Full Text: J Env Qua25, 837.pdf

Abstract: Effects of pH, Cl^-, and organic matter on Hg(II) adsorption from 10^-7 M solution by 15 New Jersey soils were examined to understand the factors responsible for Hg partitioning to soils under different environmental conditions. Maximum adsorption ranged from 86 to 98% of added Hg and occurred at pH 3 to 5. Further increasing the pH significantly decreased adsorption of the added Hg, for example, from 89±8% at pH 4.0 to 39±11% at pH 8.5, An important factor was the complexation of Hg by dissolved organic matter whose concentration increased with increasing pH. When organic matter was removed from the soil samples, adsorption decreased under acidic conditions, but increased under alkaline conditions, The effect of Cl^- on Hg(II) adsorption by soil depended on both pH and the soil organic matter content, At circumneutral and higher pH, addition of Cl^- did not affect adsorption by any soil. The standard deviation of Hg adsorption for all soils was < 4% for Cl^- concentrations from about 1×10^-6 to 1×10^-2 M. At about pH 3, the effect of Cl^- on Hg(II) adsorption by soil depended on the soil organic matter content. When the Cl^- concentration increased from about 1×0(-6) to 1×10^-2 M, adsorption by the lowest organic matter soil (1.2 g C kg^-1) decreased from 93 to 40%, whereas the measured adsorption by the largest organic matter soil (49.9 g C kg^-1) decreased only from 95 to 91%.

Keywords: Oxide-Water Interface, Sorption, Metals, Vapor

Krishnamurti, G.S.R., Cieslinski, G., Huang, P.M. and van Rees, K.C.J. (1997), Kinetics of cadmium release from soils as influenced by organic acids: Implication in cadmium availability. Journal of Environmental Quality, 26 (1), 271-277.

Full Text: J\J Env Qua26, 271.pdf

Abstract: The low-molecular-weight organic acids (LMWOAs) secreted by plant roots modify the mobility of Cd through formation of soluble complexes in the soil rhizosphere; the kinetics of Cd release as influenced by organic acids and its impact on Cd bioaccumulation remains to be established. The influence of LMWOAs (10^-3 and 10^-2 M), viz., acetic, citric, oxalic, fumaric and succinic acids, which are present in the soil rhizosphere, on the kinetics of Cd release from selected soils (Luseland, Waitville and Jedbergh) of Saskatchewan, Canada, was investigated at 25C and at an ionic strength of 0.1 M NaNO₃. It was observed that the Cd release from the soils increased initially up to a reaction period of about 2 h and then slowly decreased with time. With time, the LMWOAs were apparently microbially degraded and the soil solution Cd²⁺, which was transformed from the Cd-LMWOA complexes by microbial degradation, was adsorbed onto the negatively charged soil particles. Increasing amounts of Cd were released from the soils to the soil solution with the renewal of LMWOAs after every 2 h. The short-term (reaction period of 0.25 to 1 h) kinetics of Cd release from the soils was described by a parabolic diffusion kinetic model. The overall diffusion coefficient of the Cd release from the soil and the Cd released by the renewal of LMWOAs followed the same trend as the Cd availability index of the soils: Luseland much greater than Waitville > Jedbergh. Thus, the results presented in this investigation indicate the importance of the kinetics of the Cd release from the soils by the LMWOAs excreted by root exudates in understanding the availability of soil Cd.

? Naidu, R., Kookana, R.S., Sumner, M.E., Harter, R.D. and Tiller, K.G. (1997), Cadmium sorption and transport in variable charge soils: A review. Journal of Environmental Quality, 26 (3), 602-617.

Full Text: 1997\J Env Qua26, 602.pdf

Abstract: Alfisols, Entisols, Inceptisols, Ultisols, Vertisols, and Oxisols are all commonly found in tropical and subtropical regions receiving more than 500 mm mean annual rainfall. Landscapes throughout the tropics and subtropics are, however, dominated by Oxisols and Ultisols occupying extensive areas of potentially highly productive soils. The mineral fractions of these soils consist primarily of low-activity clays having variable surface charge that differs from high activity clays in the origin of that charge. Low activity clays are dominated by iron (Fe) and aluminium (Al) oxyhydroxides and 1:1 layer silicates (kaolin). Much research has been conducted on the effects of pH, organic matter (OM), and cation composition of the soil solution on the surface charge characteristics of variable charge soils from the tropics. In general, net negative surface charge increases with increasing soil pH and OM content. Adsorption of metal ions by variable charge soils and minerals also increases as their pH, clay, and OM contents increase. Although the precise mechanisms for the change in net negative charge of soil and mineral surfaces with increasing pH are not fully understood, the generation of negative charge either through dissociation of H+ ions from surfaces or consumption of OH- ions by soils is generally accepted. In soils dominated by permanent charge surfaces, heavy metals are not mobile but in variable charge soils, the low surface charge density creates conditions conducive to increased mobility. Consequently, the adsorption of heavy metals, in particular, cadmium (Cd) by strongly weathered soils in relation to the effects of inorganic and organic ligands and the implications for metal transport are reviewed.

Keywords: Activity, Adsorption, Adsorption Characteristics, Aluminium, Cadmium, Calcareous Soils, Clay, Clay Fractions, Density, Dissolved Organic-Carbon, Heavy Metals, Ionic-Strength, Iron, Kaolin, Mechanisms, Metal Ions, Metals, Microbial Biomass, Minerals, Mobility, Organic Ligands, Organic Matter, pH, Research, Review, Sewage-Sludge, Silicates, Soil, Soils, Solute Transport, Sorption, Surface-Charge, Surfaces, Trace-Metals, Ultisols

? Sims, J.T., Simard, R.R. and Joern, B.C. (1998), Phosphorus loss in agricultural drainage: Historical perspective and current research. Journal of Environmental Quality, 27 (2), 277-293.

Full Text: 1998\J Env Qua27, 277.pdf

Abstract: The importance of P originating from agricultural sources to the nonpoint source pollution of surface waters has been an environmental issue for decades because of the well-known rule of P in eutrophication. Most previous research and nonpoint source control efforts have emphasized P losses by surface erosion and runoff because of the relative immobility of P in soils. Consequently, P leaching and losses of P via subsurface runoff have rarely been considered important pathways for the movement of agricultural P to surface waters. However, there are situations where environmentally significant export of P in agricultural drainage has occurred (e.g., deep sandy soils, high organic matter soils, or soils with high soil P concentrations from long-term overfertilization and/or excessive use of organic wastes). In this paper we review research on P leaching and export in subsurface runoff and present overviews of ongoing research in the Atlantic Coastal Plain of the USA (Delaware), the midwestern USA (Indiana), and eastern Canada (Quebec). Our objectives are to illustrate the importance of agricultural drainage to nonpoint source pollution of surface waters and to emphasize the need for soil and water conservation practices that can minimize P losses in subsurface runoff.

Keywords: Atlantic Coastal-Plain, Heavy Clay Soil, Organic Soils, Subsurface Drainage, Suspended-Solids, Northern Belgium, Phosphate, Nitrogen, Water, Adsorption

? Sheng, G.Y., Wang, X.R., Wu, S.N. and Boyd, S.A. (1998), Enhanced sorption of organic contaminants by smectitic soils modified with a cationic surfactant. Journal of Environmental Quality, 27 (4), 806-814.

Full Text: 1998\J Env Qua27, 806.pdf

Abstract: Soils, subsoils, and aquifer materials can be modified with hydrophobic cationic surfactants to increase their sorptive capabilities for organic contaminants. In this study, we evaluated the adsorption! desorption of hexadecyltrimethylammonium (HDTMA) by smectitic soils, and the sorptive characteristics of the resultant organo-modified soils for trichloroethylene and chlorobenzene, Adsorption of HDTMA with loading levels up to 70% of the cation exchange capacity (0.70 CEC) was nearly quantitative and resulted in an equivalent release of Gale from the soils, indicating ion exchange as the sole mechanism over this range. At higher loadings, HDTMA is adsorbed by both ion exchange and hydrophobic bonding, The selectivity coefficients for HDTMA replacing Ca²⁺ were very high (10(9) - 10(7) between 0.1 and 0.8 CEC). indicating the high chemical stability of HDTMA-soil complexes at these loadings. Desorption is more significant for HDTMA adsorbed via hydrophobic bonding than via ion exchange. Sorption coefficients for trichloroethylene and chlorobenzene on HDTMA-modified soils (0.7 CEC) were 20 to 60 and 100 to 350 times higher, respectively, than those on the corresponding unmodified soils. The HDTMA derived phase was 10 to 30 and 80 to 160 times more effective than natural soil organic matter (on a unit mass basis) as a sorptive phase for trichloroethylene and chlorobenzene, respectively. A synergistic effect on sorption of trichloroethylene and chlorobenzene in binary solute systems was observed. The sorptive characteristics of HDTMA modified smectitic soils for organic contaminants are similar to those of pure HDTMA-smectites.

Keywords: Adsorption, Capacity, Cation Exchange Capacity, Cationic Surfactant, Chemical, Chemistry, Chlorobenzene, Complexes, Contaminants, Desorption, Equilibria, Exchanged Clays, HDTMA, Hexadecyltrimethylammonium, Ion, Ion Exchange, Loading, Materials, Matter, Mechanism, Modified, Natural, Organic, Organic Contaminants, Organic Matter, Partition, Range, Selectivity, Soil, Soil Organic Matter, Soils, Sorption, Stability, Surfactant, Surfactants, Water

Doussan, C., Ledoux, E. and Detay, M. (1998), River-groundwater exchanges, bank filtration, and groundwater quality: Ammonium Behavior. Journal of Environmental Quality, 27 (6), 1418-1427.

Full Text: J\J Env Qua27, 1418.pdf

Abstract: In many countries, bank-filtrated water is an important component of the drinking water production, In this case, most of the water pumped from the alluvial aquifers originates from the adjacent river. Bank filtration is generally considered beneficial both quantitatively and qualitatively. However, in some cases bank filtration ran cause deleterious effects to groundwater quality. This paper describes such a case, focusing on ammonium (NH₄) concentrations. The data were gathered at an experimental bank-filtration site which is part of a large well field along the Seine River (France). At this site, groundwater was sampled along a how line path and pore water of river bed sediments was collected with peepers or by centrifuging core samples. The pore waters of the superficial river bed sediments have high ammonium concentrations (>30 mg NH₄ L^-1) whereas, in the groundwater, these concentrations are lower (less than or equal to 20 mg NH₄ L^-1), with higher concentrations near the bank. The high NH₄ concentration in the sediment is related to the heavy organic load in the river and the mineralization of this organic matter by benthic microflora. Among the different mechanisms that influence NH₄ transport and retention in the porous medium, it emerges that sorption by the alluvial sediments (K_d approximate to 1-10×10^-3 m³kg^-1), or even the chalk (K_d approximate to 48×10^-3 m³kg^-1) seems to be effective in retaining NH₄), This is illustrated by a model of NH₄ transfer with retardation adapted to the conditions of the site, precipitation of NH₄ salts is probably not involved in regulating NH₄ concentration at this site.

Keywords: Organic-Matter, Lake Water, Infiltration, Switzerland, Diagenesis, Adsorption, Aquifer, Field

González-Pradas, E., Villafranca-Sánchez, M., Del Rey-Bueno, F., Garcia-Rodriguez, A. and Urena-Amate, M.D. (1999), Removal of aromatic amines from water by montmorillonite-(cerium or zirconium) phosphate crosslinked compounds. Journal of Environmental Quality, 28 (1), 115-120.

Full Text: J\J Env Qua28, 115.pdf

Abstract: To evaluate the potential use of two montmorillonite-(Ce or Zr) phosphate crosslinked compounds in removing organic pollutants such as aniline, p-toluidine, and p-acetylaniline from water, adsorption experiments were performed under conditions of varied temperature (288 and 308 K), Adsorption on the montmorillonite-Ce-phosphate compound was best described by a hyperbolic (H-type) isotherm, whereas for the montmorillonite-Zr-phosphate compound, S-type isotherms were obtained for p-toluidine and aniline and L-type for p-acetylaniline. Amines adsorption increases with increasing temperature on the cerium crosslinked material, while for the zirconium-crosslinked compound, adsorption decreases as temperature increases from 288 to 308 K, possibly due to a mainly physical process. Fourier-transform infrared (FTIR) spectroscopy indicated that at the pH generated by the adsorbents, the protonated species of these amines plays an important role in the adsorption process. X-ray diffraction analysis skewed that the aromatic amines are intercalated into the adsorbents. For any given amine, the cerium-montmorillonite adsorbent shows a higher capacity of adsorption compared with zirconium-montmorillonite adsorbent, so it might be reasonably used in removing aromatic amines from water.

Keywords: Aqueous-Solution, Aniline, Adsorption, Suspensions, Oxidation, Clays

Jones, C.A., Inskeep, W.P., Bauder, J.W. and Keith, K.E. (1999), Arsenic solubility and attenuation in soils of the Madison River Basin, Montana: Impacts of long-term irrigation. Journal of Environmental Quality, 28 (4), 1314-1320.

Full Text: J\J Env Qua28, 1314.pdf

Abstract: Arsenic concentrations in 850 km of the Madison and Upper Missouri Rivers exceed the Montana State human health standard (0.24 µM). In addition, ground Water As concentrations in the northern portion of the Lower Madison River Valley are above the federal drinking water standard (0.67 µM) and correlate with high soluble As levels in overlying soils. The objectives of this study were to determine processes affecting As solubility in soils of the Madison and Upper Missouri River Basins and assess potential impacts of long-term irrigation with As-rich river water on As mobility. Sixteen irrigated (>20 yr of irrigation) and nonirrigated (never irrigated) soils were sampled in four major regions adjacent to the Madison and Upper Missouri Rivers. There were no significant differences (alpha = 0.05) in total or soluble As levels between irrigated and nonirrigated soils within ang of the four regions. In addition, sorption coefficients (K_d, values in six paired soils selected for additional chemical characterization were not significantly different (cy = 0.05) between irrigated and nonirrigated soils. Ammonium oxalate extractable Fe and Mn concentrations were found to be positively correlated with fid, and Olsen P concentration was found to be negatively correlated with Kd based on a multiple linear regression (r² = 0.92). Sequential extractions performed for a subset of soils showed that labile As concentrations were similar between irrigated and nonirrigated soils. Soils that had been irrigated for >100 yr had additional As sorption capacities of at least 3 mg kg^-1 in saturated column studies following 30 Jr of simulated irrigation, Based on this suite of data, it was determined that irrigation history has not significantly affected As solubility or attenuation capacities in soils of the study area.

Keywords: Adsorption, Speciation, Phosphate, Transport, pH, 90°C, Reevaluation, Ferrihydrite, Selenium, Sorption

? Qian, J.H., Zayed, A., Zhu, Y.L., Yu, M. and Terry, N. (1999), Phytoaccumulation of trace elements by wetland plants: III. Uptake and accumulation of ten trace elements by twelve plant species. Journal of Environmental Quality, 28 (5), 1448-1455.

Full Text: 1999\J Env Qua28, 1448.pdf

Abstract: Interest is increasing in using wetland plants in constructed wetlands to remove toxic elements from polluted wastewater. To identify those wetland plants that hyperaccumulate trace elements, 12 plant species were tested for their efficiency to bioconcentrate 10 potentially toxic trace elements including As, B, Cd, Cr, Cu, Pb, Mn, Hg, Ni, and Se. Individual plants were grown under carefully controlled conditions and supplied with 1 mg L^-1 of each trace element individually for 10 d. Except B, all elements accumulated to much higher concentrations in roots than in shoots. Highest shoot tissue concentrations (mg kg^-1 DW) of the various trace elements were attained by the following species: umbrella plant (Cyperus alternifolius L.) for Mn (198) and Cr (44); water zinnia (Wedelia trilobata Hitchc.) for Cd (148) and Ni (80); smartweed (Polygonum hydropiperoides Michx.) for Cu (95) and Pb (64); water lettuce (Pistia stratiotes L.) for Hg (92), AS (34), and Se (39); and mare’s tail (Hippuris vulgaris L.) for B (1132). Whereas, the following species attained the highest root tissue concentrations (mg kg^-1 DW): stripped rush (Baumia rubiginosa) for Mn (1683); parrot’s feather (Myriophyllum brasiliense Camb.) for Cd (1426) and Ni (1077); water lettuce for Cu (1038), Hg (1217), and As (177); smartweed for Cr (2980) and Pb (1882); mare’s tail for B (1277); and monkey flower (Mimulus guttatus Fisch.) for Se (384). From a phytoremediation perspective, smartweed was probably the best plant species for trace element removal from wastewater due to its faster growth and higher plant density.

Keywords: Accumulation, Aquatic Macrophytes, Constructed Wetlands, Copper, Heavy-Metals, Hyacinth Eichhornia-Crassipes, Lemna-Minor, Phytoremediation, Pistia, Pistia Stratiotes, Polluted Water, Removal, Roots, Trace Elements, Waste-Water, Wastewater, Water Hyacinth, Wetland

? Li, Z.H. (1999), Oxyanion sorption and surface anion exchange by surfactant-modified clay minerals. Journal of Environmental Quality, 28 (5), 1457-1463.

Full Text: 1999\J Env Qua28, 1457.pdf

Abstract: In this study the sorption of nitrate (NO₃^-) and chromate (CrO₄^2-) from aqueous solution by surfactant-modified clay minerals was investigated, Both the sorption and desorption of oxyanions were found to follow a Langmuir sorption isotherm. In general, the sorption affinity is higher for chromate than for nitrate, reflecting that the interaction between the divalent anions and the surfactant bilayer is stronger than that between the monovalent anions and the surfactant bilayer. Surfactant-modified kaolinite has a higher sorption capacity for chromate. The sorption capacities for chromate and nitrate are equal for surfactant-modified illite while the sorption capacity for nitrate is higher for surfactant-modified smectite, Desorption by water revealed that chromate sorption was irreversible, while nitrate sorption was slightly reversible. In a mixed solution system, nitrate and chromate compete for the same sorption sites, resulting in a decrease in sorption capacity for each anion, Stoichiometric counterion desorption due to chromate and/or nitrate sorption further confirms that sorption of oxyanions by surfactant-modified clay minerals was due to surface anion exchange, The selectivity coefficients were higher for chromate to replace bromide than for nitrate to replace bromide for surfactant-modified kaolinite, but lower when surfactant-modified illite and smectite were the anion exchangers. The results indicate that surfactant-modified clay minerals are effective sorbents to remove anionic contaminants from water. However, the types of clay minerals should be correctly selected to maximize the contaminant removal efficiency.

Keywords: Capacity, Cationic Surfactant, Chromate, Clay, Clay Minerals, Complexes, Contaminants, Desorption, Efficiency, Interaction, Isotherm, Modified Zeolite, Nitrate, NO₃, Organic-Compounds, Removal Efficiency, Selectivity, Sites, Sorption, Sorption Capacity, Surface, Surfactant, Water

Notes: highly cited

McDowell, R.W. and Sharpley, A.N. (2001), Approximating phosphorus release from soils to surface runoff and subsurface drainage. Journal of Environmental Quality, 30 (2), 508-520.

Full Text: J\J Env Qua30, 508.pdf

Abstract: Phosphorus application in excess of crop needs has increased the concentration of P in surface soil and runoff and led many states to develop P-based nutrient management strategies. However, insufficient data are available relating P in surface soil, surface runoff, and subsurface drainage to develop sound guidelines. Thus, we investigated P release from the surface (0-5 cm depth) of a Denbigh silt loam from Devon, U.K. (30-160 mg kg^-1 Olsen P) and Alvin, Perks, Calvin, and Watson soils from Pennsylvania (10-763 mg kg^-1 Mehlich-3 P) in relation to the concentration of P in surface runoff and subsurface drainage. A change point, where the slopes of two linear relationships between water- or CaCl₂-extractable soil P and soil test phosphorus (STP) (Olsen or Mehlich-3) meet, was evident for the Denbigh at 33 to 36 mg kg^-1 Olsen P, and the Alvin and Berks soils at 185 to 190 mg Mehlich-3 P kg^-1. Similar change points were also observed when STP was related to the P concentration of surface runoff (185 mg kg^-1) and subsurface drainage (193 mg kg^-1). The use of water and CaCl₂ extraction of surface soil is suggested to estimate surface runoff P (r² of 0.92 for UK and 0.86 for PA soils) and subsurface drainage P (r² of 0.82 for UK and 0.88 for PA soils), and to determine a change point in STP, which may be used in support of agricultural and environmental P management.

Keywords: Phosphate Sorption, Desorption-Kinetics, Elovich Equation, Ionic-Strength, Losses, Management

Andersen, M.K., Raulund-Rasmussen, K., Strobel, B.W. and Hansen, H.C.B. (2002), Adsorption of cadmium, copper, nickel, and zinc to a poly(tetrafluorethene) porous soil solution sampler. Journal of Environmental Quality, 31 (1), 168-175.

Full Text: J\J Env Qua31, 168.pdf

Abstract: Received for publication October 24, 2000. Suction cups made of poly(tetrafluorethene) (PTFE) are widely used for sampling of soil solution. A brand (Prenart) of PTFE cups was tested for adsorption of Cd, Cu, Ni, and Zn at low concentrations under different conditions. In a laboratory experiment adsorption from a 10 µg L^-1 heavy metal solution with a 0.01 M NaCl background electrolyte was investigated at pH 3.6, 4.5, and 5.8 by pumping the solutions through the cups. The effect of three different ionic compositions was also investigated using 0.01 M CaCl₂, 0.01 M NaCl, and no background electrolyte at pH 4.5. In 0.01 M NaCl electrolyte at pH 5.8 the cups acted as effective filters. At pH 3.6 after 300 mL of solution had passed through the cup, equivalence between the Cd and Ni concentrations in influent and effluent was found. No equivalence between effluent ^and influent concentrations was found for Zn and Cu at pH 4.5 ^and 5.8. With Ca as the electrolyte, no adsorption of Cd, Ni, or Zn was found. In Na electrolyte, equivalence between influent ^and effluent concentrations for Cd, Ni, and Zn was reached. The difference between effluent and influent concentrations of Zn, Ni, and Cd remained significant in the absence of electrolyte. For all pH values and electrolytes the difference between effluent ^and influent concentrations of Cu was significant. It is concluded that PTFE cups affect the concentrations of heavy metals sampled at low soil solution concentrations. Cadmium, Cu, Ni, and Zn adsorb to the cup at pH > 4.5 and low ionic strength.

? Jing, S.R., Lin, Y.F., Wang, T.W. and Lee, D.Y. (2002), Microcosm wetlands for wastewater treatment with different hydraulic loading rates and macrophytes. Journal of Environmental Quality, 31 (2), 690-696.

Full Text: 2002\J Env Qua31, 690.pdf

Abstract: Constructed wetlands (CW) usually require large land areas for treating wastewater. This study evaluated the feasibility of applying CW with less land requirement by operating a group of microcosm wetlands at a hydraulic retention time (HRT) of less than 4 d in southern Taiwan. An artificial wastewater, simulating municipal wastewater containing 200 mg L^-1 of chemical oxygen demand (COD), 20 mg L^-1 of NH₄⁺-N (AN), and 20 mg L^-1 of PO₄^3--P (OP), was the inflow source. Three emergent plants [reed, Phragmites australis (Cm.) Trin. ex Steud., water primrose, Ludwigia octovalvis (Jacq.) P.H. Raven; and dayflower, Commelina communis L.] and two floating plants [water spinach, Ipomoea aquatica Forssk.; and water lettuce. Pistia stratiotes L.] plants were tested. The planted systems showed more nutrient removal than implanted systems; however, the type of macrophytes in CW did not make a major difference in treatment. At the HRTs of 2 to 4 d, the planted system maintained greater than 72. 80, and 46% removal for COD, AN, and OP, respectively. For AN and OP removal, the highest efficiencies occurred at the HRT of 3 d, whereas maximum removal rates for AN and OP occurred at the HRT of 2 d. Both removal rates and efficiencies were reduced drastically at the HRT of 1 d. Removals of COD, OP, and AN followed first-order reactions within the HRTs of 1 to 4 d. The efficient removals of these constituents obtained with HRT between 2 and 4 d indicated the possibility of using a CW system for wastewater treatment with less land requirement.

Keywords: Constructed Wetlands, Macrophytes, Nutrient Removal, Pistia Stratiotes, Water

Grafe, M., Eick, M.J., Grossl, P.R. and Saunders A.M. (2002), Adsorption of arsenate and arsenite on ferrihydrite in the presence and absence of dissolved organic carbon. Journal of Environmental Quality, 31 (4), 1115-1123.

Full Text: J\J Env Qua31, 1115.pdf

Abstract: Received for publication January 19, 2001. The adsorption of As(V) and As(III) on synthetic two-line ferrihydrite in the presence and absence of a peat humic acid (HA_p), Suwannee River fulvic acid (FA), or citric acid (CA) was investigated. Previous work with goethite has demonstrated the ability of dissolved organic carbon (DOC) to decrease As(V) and As(III) adsorption. The results obtained demonstrate that As(V) adsorption on ferrihydrite was decreased only in the presence of CA. Arsenate decreased the adsorption of all organic acids except HA_p. Both FA and CA reduced As(III) adsorption on ferrihydrite, while HA_p had no effect. Fulvic and citric acid adsorption on ferrihydrite was decreased in the presence of As(III); however, FA and CA adsorption increased at lower pH, which was consistent with decreased As(III) adsorption. Peat humic acid did not decrease As(III) adsorption, and we believe that the adsorption process of HA_p and As(III) and As(V) on ferrihydrite are independent of each other. Previously, we observed that As(V) adsorption on goethite decreased in the presence of HA_p > FA > CA, while As(III) adsorption on goethite was decreased similarly to that on ferrihydrite in the presence of CA > FA  HA_p, yet As(III) adsorption on ferrihydrite was greater than on goethite. The observed differences between this study and the earlier study on goethite are believed to be an intricate function of ferrihydrite’s surface characteristics, which affect the mechanisms of adsorption ^and hence the affinity of organic acids such as HA_p, FA, and CA for the ferrihydrite surface. As such, the adsorption of DOCs to ferrihydrite are assumed to be less favorable and to occur with a fewer number of ligands, resulting in lower surface coverage of weaker bond strength

Keywords: AHS, Acidified Humic Substance, CA, Citric Acid, DOC, Dissolved Organic Carbon, DOM, Dissolved Organic Matter, FA, Suwannee River fulvic acid, HA_p, Peat Humic Acid

? Spadotto, C.A. and Hornsby, A.G. (2003), Soil sorption of acidic pesticides: Modeling pH effects. Journal of Environmental Quality, 32 (3), 949-956.

Full Text: 2003\J Env Qua32, 949.pdf

Abstract: A model of acidic pesticide sorption in soils was developed from theoretical modeling and experimental data, which initially considered a combination of a strongly acidic pesticide and a variable-charge soil with high clay content. Contribution of 2,4-D [(2,4-dichlorophenoxy) acetic acid] anionic-form sorption was small when compared with molecular sorption. Dissociation of 2,4-D was not sufficient to explain the variation in K-d as a function of pH. Accessibility of soil organic functional groups able to interact with the pesticide (conformational changes) as a function of organic matter dissociation was proposed to explain the observed differences in sorption. Experimental 2,4-D sorption data and K-oc values from literature for flumetsulam [N-(2,6-difluorophenyl)-5-methyl [1,2,4] triazolo [1,5-a] pyrimidine-2-sulfonamide] and sulfentrazone [N-[2,4-dichloro-5-[4-(difluromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl] phenyl] methanesulfonamide] in several soils fit the model.

Keywords: Adsorption, Mobility, Chlorsulfuron, Degradation, Adsorbents, Retention, Sediments, Imazaquin, Bentazon, Systems

? Simpson, M.J., Chefetz, B. and Hatcher, P.G. (2003), Phenanthrene sorption to structurally modified humic acids. Journal of Environmental Quality, 32 (5), 1750-1758.

Full Text: 2003\J Env Qua32, 1750.pdf

Abstract: Several studies emphasize the importance of soil organic matter characteristics in hydrophobic contaminant sorption and outline the strong dependence of sorption on organic matter aromaticity. In this study, the role of organic matter aromaticity in phenanthrene sorption was investigated using humic acids (HAs) from compost, peat, and soil that were structurally modified by bleaching, hydrolysis, oximation, and subcritical water extraction. The HAs were characterized with cross polarization magic angle spinning carbon-13 nuclear magnetic resonance (CPMAS C-13 NMR) spectroscopy and used in batch equilibrations with phenanthrene. Bleaching substantially reduced the aromaticity of the samples whereas the other treatments increased the relative aromaticity. Phenanthrene sorption increased, even though there was a substantial reduction in sorbent aromaticity with some samples. The HAs that exhibited comparable CPMAS C-13 NMR spectra and aromaticity did not behave similarly with respect to phenanthrene sorption. When the sorption data (K-oc values) were correlated to sample aromaticity, the correlation coefficients (r(2)) did not exceed 0.39. Comparisons with the atomic H to C ratio provided slightly better r(2) values (up to 0.54). This study demonstrates that macroscopic sorbent characteristics could not explain the observed phenanthrene sorption coefficients, aliphatic structural components of HAs can contribute appreciably to phenanthrene sorption, and organic matter physical conformation may regulate access to organic matter structures. Therefore, the use of only macroscopic sorbent properties, such as aromaticity, to predict and rationalize sorption values cannot solely be used to explain the behavior of organic contaminants in soil environments.

Keywords: Access, Acids, Behavior, Binding, Bleaching, C-13, C-13 Nmr, Carbon 13, Carbon-13, Chemical Modifications, Compost, Contaminants, Correlation, Cpmas, Dependence, Distributed Reactivity Model, Extraction, Humic, Humic Acids, Hydrolysis, Importance, Magnetic, Matter, Modified, NMR, Nmr Spectra, Organic, Organic Contaminants, Organic Matter, Peat, Polarization, Polycyclic Aromatic-Hydrocarbons, Predict, Properties, Pyrolysis-Gas, Reduction, Sediments, Soil, Soil Organic Matter, Soil Organic-Matter, Sorption, Spectrometry, Spectroscopy, Substances, Water

? Sullivan, E.J., Bowman, R.S. and Legiec, I.A. (2003), Sorption of arsenic from soil-washing leachate by surfactant-modified zeolite. Journal of Environmental Quality, 32 (6), 2387-2391.

Full Text: 2003\J Env Qua32, 2387.pdf

Abstract: Post-treatment of leachate from soil-washing remedial actions may be necessary depending on the amounts of dissolved contaminants present. Uptake of arsenic species by surfactant-modified zeolite (SMZ) from a synthetic soil leachate (pH of approximately 12 [NaOH]) was measured as a test of SMZ as a post-treatment sorbent. Batch sorption isotherms were prepared using leachate to SMZ ratios from 40:1 to 4:1, and temperatures of 25 and 15degreesC. Equilibrium levels of dissolved and total solution arsenic were similar. At each temperature, sorption appeared to reach a plateau or maximum, then decreased at the highest solution concentration, corresponding to the lowest amount of zeolite added (2.5 g). A maximum sorption value of 72.0 mmol of arsenic per kg of SMZ (5400 mg/kg) was observed at 25degreesC, and 42.1 mmol/kg (3150 mg/kg) at 15degreesC. Total arsenic recoveries varied from 74 to 125%. Surfactant-modified zeolite removed up to 97% of dissolved organic carbon and decolorized the leachate solutions. Excluding the points for the highest arsenic to SMZ ratio, the sorption isotherms were well described by the linearized form of the Langmuir equation, with coefficients of determination greater than 0.90 at both temperatures. Sorption of arsenic by SMZ is attributed to anion exchange with counterions on the surfactant head groups, and/or partitioning of organic carbon-complexed arsenic into the surfactant bilayer.

Keywords: Adsorption, Arsenic, Carbon, Chromate, Clinoptilolite, Concentration, Contaminants, Determination, Dissolved, Dissolved Organic Carbon, Isotherms, Leachate, Natural Zeolites, Organic, Organic Carbon, Oxyanions, Partitioning, pH, Soil, Solids, Sorption, Sorption Isotherms, Surfactant, Temperature, Zeolite

? Milfont, M.L., Martins, J.M.F., Antonino, A.C.D., Gouveia, E.R., Netto, A.M., Guine, V., Mas, H. and Freire, M.B.G.D. (2008), Reactivity of the plant growth regulator paclobutrazol (cultar) with two tropical soils of the northeast semiarid region of Brazil. Journal of Environmental Quality, 37 (1), 90-97.

Full Text: 2008\J Env Qua37, 90.pdf

Abstract: The reactivity of paclobutrazol (PBZ, a plant growth retardant) with a Yellow Ultisol and a Vertisol from the semiarid northeast region of Brazil was evaluated through batch sorption experiments and modeling. Although not instantaneous, the sorption kinetic of PBZ (pure and formulated) was fast (a few hours) in both soils. The sorption kinetics were well described by a second-order (ds/dt = k(2) (S-e2 - S-1)(2)) but not by a first-order model. The sorption isotherms were found to be linear and the calculated K-D values were 8.8  0.11 and 7.4  0.2 L kg^-1 for pure PBZ in the Ultisol and the Vertisol, respectively. The corresponding K-OC values were 1275  34 logK(OC) = 3.11) and 1156  49 (logK(OC) = 3.06) L kg^-1, respectively. Considering the very differenc texture of the two soils and the similar K-OC values determined, these results showed that in both soils, the sorption of PBZ is dominantly controlled by organic matter, although some interactions of PBZ with iron oxides (goethite) were observed in the Ultisol. Based on these sorption parameters a low leachability potential of PBZ in soils is anticipated, as they correspond to a groundwater ubiquity score (GUS) ranging from 2.0 to 2.7, i.e., moderately to not mobile, in contradiction with the actual groundwater situation in Brazil. This work stresses the need to evaluate and predict the risk associated with aquifer contamination by this widely used plant growth regulator.

Keywords: Brazil, Degradation, Groundwater, Growth, Iron, Isotherms, Kinetic, Kinetics, Leachability, Liquid-Chromatography, Microorganisms, Modeling, Performance, Persistence, Pesticides, Residues, Sorption, Transport, Unsaturated Soil

? Boudesocque, S., Guillon, E., Aplincourt, M., Martel, F. and Noel, S. (2008), Use of a low-cost biosorbent to remove pesticides from wastewater. Journal of Environmental Quality, 37 (2), 631-638.

Full Text: 2008\J Env Qua37, 631.pdf

Abstract: A lignocellulosic substrate (LS) obtained from our local agroindustry was used as a low-cost and effective adsorbent for the removal of pesticides from wastewaters. The studied pesticides were terbumeton (N-(1,1-dimethyl)-N’ethyl-6-methoxy-1,3,5-triazine-2,4-diamine), desethyl terbumeton (N-(1,1-dimethylethyl)-6-methoxy-1,3,5-triazine-2,4-diamine), dimetomorph (4-[3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl) acryloyl]morpholine), and isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea). Batch and column experiments were conducted as a function of pH and pesticide concentration under laboratory and industrial conditions. The concentration range studied for the pesticides varied from 210^-7 to 310^-4 mol L^-1. The influence of organic and inorganic pollutants was assessed by studying the retention of pesticide in the presence of copper(II) and a surfactant. These experiments indicated that LS is an efficient adsorbent toward the investigated pesticides and has little influence of the other pollutants. The kinetic adsorptions are fast, and the amounts of adsorbed pesticide varied from 1 to 8 g kg^-1 of LS. These retention capacities show that LS can provide a simple, effective, and cheap method for removing pesticides from contaminated waters. Thus, this biomaterial may be useful for cleaning up polluted waters.

Keywords: Sugar-Industry Waste, Bagasse Fly-Ash, Lignocellulosic Substrate, Wheat Bran, Adsorption, Sorption, Carbon, Surfactant, Residue, System

? Wagner, D.J., Elliott, H.A., Brandt, R.C. and Jaiswal, D. (2008), Managing biosolids runoff phosphorus using buffer strips enhanced with drinking water treatment residuals. Journal of Environmental Quality, 37 (4), 1567-1574.

Full Text: 2008\J Env Qua37, 1567.pdf

Abstract: Vegetated buffers strips typically have limited ability to reduce delivery of dissolved phosphorus (DP) from agricultural fields to surface waters. A field study was conducted to evaluate the ability of buffer strips enhanced with drinking water treatment residuals (%WRs) to control runoff P losses from surface-applied biosolids characterized by high water-extractable P (4 g kg^-1). Simulated rainfall (62.4 mm h^-1) was applied to grassed plots (3 m×10.7 rn including a 2.67 m downslope buffer) surface-amended with biosolids at 102 kg P ha^-1 until 30 min of runoff was collected. With buffer strips top-dressed with WTR (20 Mg ha^-1), runoff total P (TP = 2.5 mg L^-1) and total DP (TDP = 1.9 mg L^-1) were not statistically lower (a = 0.05) compared to plots with unamended grass buffers (TP = 2.7 mg L^-1; TDP = 2.6 mg L^-1). Although the applied WTR had excess capacity (Langmuir P maxima of 25 g P kg^-1) to sorb all runoff P, kinetic experiments suggest that sheet flow travel time across the buffers (similar to 30 s) was insufficient for significant P reduction. Effective interception of dissolved P in runoff water by WTR-enhanced buffer strips requires rapid P sorption kinetics and hydrologic flow behavior ensuring sufficient runoff residence time and WTR contact in the buffer. Substantial phosphate-adsorbent contact opportunity may be more easily achieved by incorporating WrRs into P-enfiched soils or blending WTRs with applied P sources.

Keywords: Surface Runoff, Extractable Phosphorus, Reduce Phosphorus, Sorption Capacity, Amended Soils, Manure, Management, Aluminum, Losses, Retention

? Xu, Z.Y., Fan, J., Zheng, S.R., Ma, F.F. and Yin, D.Q. (2009), On the adsorption of tetracycline by calcined magnesium-aluminum hydrotalcites. Journal of Environmental Quality, 38 (3), 1302-1310.

Full Text: J Env Qua38, 1302.pdf

Abstract: Exploiting effective sorbents for antibiotic adsorption is highly, desirable for the elimination of ecological risks from antibiotic contamination. In this study, MgAl-CO₃^2- hydrotalcites with different Mg/Al molar ratios were prepared and tetracycline (TC) adsorption to the hydrotalcites and calcined hydrotalcites was investigated by batch experiments. Calcined hydrotalcites had higher adsorption capacities compared to MgAl-CO₃^2- hydrotalcites. At low TC equilibrium concentrations, calcined hydrotalcites with differing Mg/Al ratios showed approximately identical TC uptakes. However, at high tetracycline concentration, greater TC adsorption capacity was observed for calcined hydrotalcite having a high Mg/Al ratio (i.e., 4.4). X-ray diffraction (XRD) characterization showed the presence of Mg-Al oxide solid solution in TC -loaded calcined hydrotalcite, suggesting that suspension of the calcined product in water and adsorption of TC had led to only partial reconstruction of the layered structure. We hypothesize that TC was adsorbed on the MgO surface at high equilibrium concentrations. The behavior of TC adsorption on the calcined hydrotalcite was well described by a dual adsorption model. Kinetic analysis suggested that at low adsorption levels, TC adsorption by calcined hydrotalcite could be modeled by both a pseudo second-order kinetics model and a nucleation-growth model. The present work demonstrates that calcined hydrotalcites may be promising adsorbents for effective removal of TC From water resources.

Keywords: Adsorption, Antibiotics, Aqueous-Solutions, Degradation, Layered Double Hydroxides, Mg, Mixed Oxides, Physicochemical Properties, Removal, Sorption, Water

? Saad, R., Thibutot, S., Ampleman, G. and Hawari, J. (2010), Sorptive removal of trinitroglycerin (TNG) from water using nanostructured silica-based materials. Journal of Environmental Quality, 39 (2), 580-586.

Full Text: 2010\J Env Qua39, 580.pdf

Abstract: Trinitroglycerin (TNG), a nitrate ester, is widely used in the pharmaceutical industry for the treatment of angina pectoris (chest pain) And by the military for the manufacturing of dynamite and propellants. Currently, TNG is considered as a key environmental contaminant due to the discharge of wastewater tainted with the chemical from various military and pharmaceutical industries. The present study describes the use of a nanostructured silica material (Mobil Composite Material no. 48 [MCM-48]) prepared by mixing tetraethylorthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) to remove TNG from water. The sorption of TNG onto MCM-48 rapidly reached equilibrium within I It. Sorption kinetics were best described using a pseudo-second order model, whereas sorption isotherms were best interpreted using the Langmuir model. The latter gave a maximum sorption capacity of 55.2 mg g^-1 at 40ºC. The enthalpy and entropy of TNG sorption onto MCM-48 were 1.89 kJ mol^-1 and 79.0 J mol^-1. K^-1, indicating the endothermic nature of the TNG sorption onto MCM-48. When MCM-48 was heated at 540ºC for 5 It, the resulting calcined material (absence of the surfactant) did not sorb TNG, suggesting that the surfactant component of the nanomaterial was responsible for TNG sorption. Finally, we found that MCM-48 lost approximately 30% of its original sorption capacity after five sorption-desorption cycles. In conclusion, the nanostructured silica based sorbent, with high sorption capacity and remarkable reusability, should constitute the basis for the development of an effective technology for the removal of TNG from contaminated water.

Keywords: Activated Carbons, Adsolubilization, Adsorption Properties, Anaerobic Biodegradation, Bromide, Calcined, Capacity, Chemical, Chest Pain, Composite, Contaminant, CTAB, Development, Discharge, Endothermic, Enthalpy, Entropy, Environmental, Equilibrium, Explosives, Isotherms, Kinetics, Langmuir, Langmuir Model, Manufacturing, MCM-48, Mesoporous Silica, Mixing, Model, Nanomaterial, Nitrate, Nitrate Anions, Nitroglycerin, Organic Pollutants, Pain, Pharmaceutical Industry, Pseudo Second Order, Pseudo-Second Order, Pseudo-Second Order Model, Pseudo-Second-Order, Removal, Reusability, Silica, Sorbent, Sorption, Sorption Capacity, Sorption Isotherms, Sorption Kinetics, Sorption-Desorption, Structural Characteristics, Surfactant, Technology, TEOS, Treatment, Wastewater, Water

? Ganjegunte, G.K., Vance, G.F., Gregory, R.W., Urynowicz, M.A. and Surdam, R.C. (2011), Improving saline-sodic coalbed natural gas water quality using natural zeolites. Journal of Environmental Quality, 40 (1), 57-66.

Full Text: 2011\J Env Qua40, 57.pdf

Abstract: Management of saline-sodic water from the coalbed natural gas (CBNG) industry in the Powder River Basin (PRB) of Wyoming and Montana is a major environmental challenge. Clinoptilolite zeolites mined in Nevada, California, and New Mexico were evaluated for their potential to remove sodium (Na⁺) from CBNG waters. Based on the exchangeable cation composition, naturally occurring calcium (Ca²⁺)-rich zeolites from New Mexico were selected for further evaluation. Batch adsorption experiments were conducted to evaluate the potential of the Ca²⁺-rich natural clinoptilolites to remove Na⁺ from saline-sodic CBNG waters. Batch adsorption experiments indicated that Na+ adsorption capacity of clinoptilolite ranged from 4.3 (4 x 6 mesh) to 7.98 g kg^-1 (14 x 40 mesh). Among the different adsorption isotherms investigated, the Freundlich Model fitted the data best for smaller-sized (6 x 8, 6 x 14, and 14 x 40 mesh) zeolites. Passing the CBNG water through Ca²⁺-rich zeolite columns reduced the salt content (electrical conductivity [EC]) by 72% with a concurrent reduction in sodium adsorption ratio (SAR) from 34 (typical level in northwestern PRB) to 10 mmol(1/2) L-1/2. Zeolite technology appears to be an effective water treatment alternative to industrial membrane treatment for removing Na+ from poor-quality CBNG waters.

Keywords: Adsorption, Adsorption Capacity, Adsorption Isotherms, Alternative, Batch Adsorption, Calcium, California, Capacity, Cation, Challenge, Clinoptilolite, Composition, Conductivity, Data, Drainage, Electrical Conductivity, Environmental, Evaluation, Experiments, Freundlich, Ions, Isotherms, Land Application, Membrane, Mexico, Mine, Model, Montana, Na⁺, Natural, Natural Gas, Nevada, New Mexico, Potential, Powder River Basin, Reduction, Removal, Salt, SAR, Sodium, Sodium Adsorption Ratio, Soil, Sorption, Systems, Technology, Treatment, Water, Water Treatment, Waters, Zeolite, Zeolites

? Zhang, M.H. and Xu, J.M. (2011), Nonpoint source pollution, environmental quality, and ecosystem health in China: Introduction to the special section. Journal of Environmental Quality, 40 (6), 1685-1694.

Full Text: 2011\J Env Qua40, 1685.pdf

Abstract: The rapid economic and industrial growth of China, exemplified by a 10-fold increase in its gross domestic product in the past 15 years, has lifted millions of its citizens out of poverty but has simultaneously led to severe environmental problems. The World Health Organization estimates that approximately 2.4 million deaths in China per year could be attributed to degraded environmental quality. Much of China’s soil, air, and water are polluted by xenobiotic contaminants, such as heavy metals and organic compounds. In addition, soil quality is degraded by erosion, desertification, and nutrient runoff. Air quality is further compromised by particulates, especially in heavily populated areas. Research shows that 80% of urban rivers in China are significantly polluted, and poor water quality is a key contributor to poverty in rural China. Economic and industrial growth has also greatly expanded the demand for water sources of appropriate quality; however, pollution has markedly diminished usable water resource quantity. Desertification and diminishing water resources threaten future food security. In recent years, China’s government has increased efforts to reverse these trends and to improve ecosystem health. The Web of Science database showed that the percentage of articles on China devoting to environmental sciences increased dramatically in recent years. In addition, the top 25 institutes publishing the papers in environmental sciences were all in China. This special issue includes seven articles focusing on nonpoint source pollution, environmental quality, and ecosystem health in China. The major issues, and results of these studies, are discussed in this introduction.

Keywords: Air-Pollution, China, Climate-Change, Constructed Wetlands, Environmental, Environmental Sciences, Erosion, Growth, Health, Heavy Metals, Heavy-Metal Ions, Herbicide Butachlor, Metals, Nonpoint Source Pollution, Organic Compounds, Organic-Matter, Papers, Pig Manure, Pollution, Potential Contributions, Poverty, Publishing, Quality, Research, Science, Sciences, Soil, Trends, Urban, Waste-Water, Water, Web of Science, Yellow-River