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Papers by Les Evans

Journal of Soil Science, 1987

SUMMARYThirty‐one soil solutions were extracted by immiscible displacement with CCl4 under high s... more SUMMARYThirty‐one soil solutions were extracted by immiscible displacement with CCl4 under high speed centrifugation from sub‐horizons of three podzolic soils from north‐eastern Ontario, Canada. The solutions were analysed for major cations and anions and a speciation of dissolved Fe and Al was attempted to distinguish ‘free’, ‘organically bound’ and ‘inorganically bound’ species. Results indicated that the Ae (E) horizon solutions were of low pH and contained mainly organically bound Fe and Al. With depth, pHs increased, ionic strengths decreased and the relative proportion of inorganically bound Fe and Al increased. Although application of phase diagrams permitted only a semi‐quantitative interpretation of the data, all horizon solutions, with the exception of some Ae solutions, appeared supersaturated with respect to likely occurring crystalline and amorphous aluminosilicates [kaolinite, halloysite, allophane (Al:Si=l) and imogolite]. Of the phases considered, reactions involving...

Geoscience Canada, 1982

Paleosols, particularly buried paleosols, have proved valuable stratigraphic markers in many Quat... more Paleosols, particularly buried paleosols, have proved valuable stratigraphic markers in many Quaternary studies. They are most commonly found buried by loess in central Europe and the United States, and by volcanic ash in the Pacific margins. Within their morphologies are recorded evidence of past climates and vegetations. The understanding of paleosols has paralleled our comprehension of contemporary soils and hence the methods of investigation of paleosols are those that have found common usage in the study of the soils of today. The recognition of paleosols is thus largely based on the identification of characteristics known in contemporary soils. The usefulness of paleosols as stratigraphic indicators is in part due to their extensive and recognisable occurrence over large areas and because they often contain material suitable for absolute dating by the 14C method. Wood, charcoal, peat and soil organic matter have all been employed in the dating of paleosols. 14 C dating of seco...

Clay Minerals, 1975

Lower Palaeozoic mudstones from Cwmcadian, Gwynedd are dominantly composed of quartz, illite and ... more Lower Palaeozoic mudstones from Cwmcadian, Gwynedd are dominantly composed of quartz, illite and chlorite, with subordinate albite, orthoclase and rutile. Chemical formulae are determined for chlorite and illite using a combination of chemical and X-ray data. The formulae indicate that the illite is dioctahedral and suggest that the chlorite structure contains one dioctahedral and one trioctahedral layer. The hypothesis is put forward that both minerals formed from a dioctahedral mineral; illite from a non-expanded form and chlorite from an 'open' form by precipitation of a Fe2+/Mg hydroxide interlayer.

Canadian Journal of Soil Science, 1982

Humo-Ferric Podzols (Typic Cryorthods) developed on glacial till or glaciolacustrine deposits wer... more Humo-Ferric Podzols (Typic Cryorthods) developed on glacial till or glaciolacustrine deposits were sampled in the Chapleau-Foleyet area of northeastern Ontario. pHs of Ae horizons ranged from 3.30 to 4.20 and of C horizons from 4.40 to 4.85. Cation exchange capacities (CEC) of mineral soil horizons averaged 1.7 meq/100 g, whilst those of the forest humus (fibrimors) averaged 166 meq/100 g. The CECs of the Bf and BC horizons were highly pH-dependent, averaging 3.2 meq/100 g at pH 4 and 16.8 meq/100 g at pH 8. The pH-dependency of CEC in these horizons was believed to be due to Al-complexes with organic matter. Calculated elemental loss using Zr as an internal standard showed significant losses of Mg, Fe, Ca and Al from Ae (albic) horizons and gains of Fe and, to a lesser extent, gains of Al in Bf (spodic) horizons. The clay mineralogy of Ae horizons was dominated by a high-charge smectite and that of Bf and BC horizons by chlorite.

Canadian Journal of Soil Science, 1979

The pedological development of a chronosequence of four soils ranging in age from 8000 to 115 000... more The pedological development of a chronosequence of four soils ranging in age from 8000 to 115 000 yr was investigated on Baffin Island, N.W.T. All the soils were developed on granitic morainal material in an Arctic environment. The soils were acid and very gravelly with low clay contents. The major clay minerals in all horizons were illite and ’aluminous’ vermiculite. A number of soil properties changed with time and of these, depth of solum was the most significant. The estimated rate of solum development for the four soils averaged 1.0 cm/1000 yr.

Encyclopedia of Earth Sciences Series, 2008

Waste Management & Research, 1993

The purpose of this study was to examine the relationship between the concentration of boron (B) ... more The purpose of this study was to examine the relationship between the concentration of boron (B) and some other selected trace elements in soil solution as effected by hydrogen ion activity within the normal pH range for acidic soils commonly amended with agricultural limestone and, alternatively, alkaline fly ash. Sluiced alkaline fly ash was applied to an acidic, clay textured soil at rates equivalent to 0, 42, 84, 125 and 167 tonne ha-1 based on the soil lime requirement. After wheat was grown and harvested the soil-ash mixtures were maintained at field capacity moisture content for an additional 4 months before pore water samples were extracted by immiscible displacement. The total concentrations of Co, Cr, Fe, V and Zn in the ash treated soils increased by < 10% at the highest application rate of ash, the content of Cu was increased by 13% and B by 38%. Only the concentration of boron increased appreciably in the pore water extracts. Release of B from the ash was correlated ...

Soil Science Society of America Journal, 1983

Canadian Journal of Soil Science, 1978

Massive, but very localized, iron formations have been noted in some Humic Gleysols in southern O... more Massive, but very localized, iron formations have been noted in some Humic Gleysols in southern Ontario. Some of these formations weigh up to 9 kg, and invariably occur at the contact zone between sandy loam to loam surface horizons and underlying clay-rich subsoils. The contents of Fe2O3 and MnO2 of 16 samples varied from 19.6 to 49.9% and 0.8 to 11.1%, respectively, although no crystalline oxides or hydroxides of Fe or Mn could be detected by X-ray diffraction. The localized occurence of these formations suggests that Fe2+ and Mn2+ are moving laterally through the subsoil and oxidizing at some seepage point downslope in the more aerated surface horizons.

Journal of Soil Science, 1970

Canadian Journal of Soil Science, 1987

The retention of B by 20 agricultural soils from Ontario was investigated by equilibration of the... more The retention of B by 20 agricultural soils from Ontario was investigated by equilibration of the soils with various concentrations of boric acid. The retention of B conformed to both Langmuir and Freundlich adsorption isotherms for all but one soil. Adsorption maxima were calculated for both isotherms and from simple linear regression analysis only pH was found to be significantly correlated with the calculated adsorption maxima. For soils with pH above 6.8, the Langmuir adsorption maxima were significantly correlated with organic C and water-soluble carbohydrate contents. Application of phase diagrams indicated that, under the experimental conditions employed, the solutions of some of the acidic soils were supersaturated with respect to the Ca-containing borate minerals inyoite, colemanite and nobleite and, given a number of reasonable assumptions, that at rates of B application of 3 kg ha−1, acidic soils could be supersaturated with respect to the mineral nobleite. The extent of ...

Geoderma, 2007

The regional geochemical survey of soils in Jiangsu Province is an important part of a larger agr... more The regional geochemical survey of soils in Jiangsu Province is an important part of a larger agro-geological survey program in China. This paper presents chemical data from soils sampled at two depths; top-soils from a 0–20 cm depth and sub-soils from a 150–200 cm depth. Results for eleven of the fifty four elements measured are presented for approximately 103,000 top-soils and 26,000

Cement or lime can be used to treat trace element contaminated soils, reducing their mobility due... more Cement or lime can be used to treat trace element contaminated soils, reducing their mobility due to increased soil pH which enhances precipitation and adsorption, and also due to pozzolanic reactions and cementation. In the present work, an alkaline and an acidic soil both containing Cd, Co, Cu, Ni, Pb, Sb and Zn from either geogenic or geogenic and anthropogenic origin were treated with cement or calcium hydroxide. Soils were then extracted with dilute HNO(3) or NaOH solution of different concentrations to obtain extracts of different pH (pH 4-12). In untreated soils, Co, Cu, Ni and Pb in solutions were detected at alkaline pH. The addition of cement or Ca(OH)(2) reduced the mobility of every trace element at high pH, but enhanced the mobility of Cd, Co, Cu, Ni, Pb and Zn at low pH. Metal mobilisation at high pH was observed for Cu in the acidic soil due to the liberation of dissolved organic matter. Below pH 6, Sb mobility was lower in the cement-treated soil compared to the untreated soil, but the same in the Ca(OH)(2) treated soil as in the control soil. Comparison with theoretical trace element precipitates suggested that the mobility of trace elements is likely reduced at high pH by encapsulation and immobilisation within the cement matrix rather then precipitation.

Soil Science Society of America Journal, 1994

. Soil solution chemistry and alfalfa response to CaCO 3 and MgCO 3 on an acidic Gleysol. Can. J.... more . Soil solution chemistry and alfalfa response to CaCO 3 and MgCO 3 on an acidic Gleysol. Can. J. Soil Sci. 76: 41-47. Soil acidity is a limiting factor for forage production. Liming is a common agricultural practice for acid soils, yet there is limited information on the effects of soil solution chemistry in response to liming. Soil from the Ap horizon of an Orthic Humic Gleysol was amended with 0, 2.5 or 5.0 g CaCO 3 kg -1 and 2.1 or 4.2 g MgCO 3 kg -1 to determine the changes due to liming in soil solution composition before planting and after three cuts of alfalfa (Medicago sativa L.). The soil solution samples were extracted by immiscible displacement with C 2 Cl 4 . The low equivalent rate of CaCO 3 and MgCO 3 decreased the concentrations of Fe from 889 to less than 22 µM, Mn from 286 to less than 6 µM, Al from 45 µM to undetectable level before plant growth. Soil pH, dissolved organic carbon (DOC), Cu and NH 4 -N concentrations in the soil solutions extracted after the third cut of alfalfa were increased compared with those measured before planting. Concentrations of Ca, Mg, K, Na, Mn, Zn, Fe, Al, NO 3 -N, SO 4 and Si were all decreased after the third cut compared with those measured before planting. Step-wise multiple regression analysis indicated that the dry matter (DM) yield of the first cut was positively correlated to NO 3 -N and negatively correlated to Mn concentration in the soil solutions (R 2 = 0.65**); whereas the DM yield of the second and third cuts and of the roots were negatively correlated with Mn concentrations (R 2 = 0.75**, 0.63**, and 0.60**, respectively). The regression analysis supported visual Mn toxicity, suggesting that Mn toxicity, not Al concentration, was the main limitation to alfalfa growth in unlimed soil.

$Research paper thumbnail of Boron fractionation in soils$

Communications in Soil Science and Plant Analysis, 1994

ABSTRACT A chemical fractionation scheme for boron (B) developed previously for minerals and synt... more ABSTRACT A chemical fractionation scheme for boron (B) developed previously for minerals and synthetic soils was used on twenty-four soils with a wide range of physical-chemical properties. The scheme differentiated soil B as readily soluble (0.01M CaCl2), specifically adsorbed (0.05M KH2PO4), oxide bound (0.20M acidic NH4-oxalate), organically bound (0.02M HNO3 + 30% H2O2), and residual (HNO3 + HCl + HF). On the average, the readily soluble and specifically adsorbed B fractions accounted for less than 2% of the total soil B in a sequential extraction procedure. Mean contents of extractable B were 2.3% associated with various oxides and oxyhydroxides, and 8.6% in organically bound forms. The major portion of soil B existed in residual or occluded forms. The procedure was found to be satisfactory in terms of sensitivity and precision for the fractionation of B. A highly linear correlation coefficient of 0.972 was found between the sum of the five B fractions and total soil B content. Readily soluble B was positively correlated with both pH and cation exchange capacity (CEC), while negatively correlated with contents of DCB-extractable aluminum (Al). Specifically adsorbed B was only correlated with the DCB-extractable iron (Fe) content. Organically bound B was correlated with the contents of both clay and organic carbon (C). The general agreement between the separate and sequential extraction procedures suggested that the fractionation scheme was reasonably feasible.

ABSTRACT The concentrations of zinc in Ross Lake, a small, relatively shallow lake adjacent to th... more ABSTRACT The concentrations of zinc in Ross Lake, a small, relatively shallow lake adjacent to the Hudson Bay Mining and SmeltingCompany smelter in Flin Flon, Manitoba, Canada, have risenrecently to levels that may soon approach environmental concern.Six locations were sampled, five sites in Ross Lake and one sitein Flin Flon Creek and sampling occurred in four sampling dates.Water was collected from two sampling depths, together with asample of the underlying sediment. Aqua regia extraction of thesediments dissolved large amounts of both zinc and sulphur,averaging 28 800 mg kg-1 for zinc and 40 700 for sulphur.Much smaller amouns of Zn occurred in organic, 266 mg kg-1,and specifically adsorbed forms, 192 mg kg-1. X-raydiffraction analysis confirmed the presence of sphalerite, ZnS,in the sediments. Average contents of Zn in the waters for thefour sampling dates were 838 µg L-1, 572 µgL-1, 619 µg L-1 and 222 µg L-1. Aqueousspeciation calculations indicated that the predominant speciespresent in oxygenated waters were ZnSO04, ZnL0,Zn(OH)02 and ZnCO03and that ZnS(HS)- wasthe predominant species at the sediment/water interface.

Environmental Science & Technology, 1989

For thousands of years, soil has been the repository of society's wastes. The excavation of midde... more For thousands of years, soil has been the repository of society's wastes. The excavation of middens, which has provided archaeologists with valuable information on the daily life of past civilizations, has shown that land disposal has been carried out since antiquity. In recent years, however, the rapid increase in the disposal of municipal and industrial wastes in landfdl sites, and the application bcth of leachates from these landfill sites and of sewage sludge to land, is causing much concern about environmental pollution. Moreover, metals also are being added to soil either directly through agricultural practices or indirectly through the atmospheric precipitation of industrial pollutants and automobile emissions.

pedago.cegepoutaouais.qc.ca

ABSTRACT: Concrete in farm buildings is subjected to severe hydrogen sulphide and sulphate concen... more ABSTRACT: Concrete in farm buildings is subjected to severe hydrogen sulphide and sulphate concentrations that result in the corrosion of reinforced concrete. Corrosive gases are released from stored manure. Of these, hydrogen sulphide is the most corrosive agent ...