Les M. Lavkulich

Sorption behavior of copper, zinc, and cadmium in response to simulated changes in soil properties

Abstract Environmental changes and management practices which alter soil properties may affect the capacity of soils to sorb trace metals, such as copper (Cu), zinc (Zn), and cadmium (Cd), and thus influence the bioavailability and leach ability of the metals. Two agricultural soils were treated to partially oxidize organic matter and to decrease soil pH for evaluating the effects of acidification and organic matter oxidation on trace metal sorption onto soils. For the one soil with a pH value of 6.74 and organic carbon (C) content of 46.9 g‐kg‐1, loss of 11% of its organic matter reduced by 97, 72, and 62% the original sorption capacity for Cu, Zn, and Cd, respectively, while the corresponding values caused by acidifying the soil one pH‐unit were 32, 16, and 29%. For the another soil with a pH of 4.69 and organic C content of 16.3 g‐kg‐1, a decrease in pH by one unit resulted in a loss of 43, 21, and 52% of the sorption capacity for Cu, Zn, and Cd, respectively.

New classification systems for tropical organic-rich deposits based on studies of the Tasek Bera Basin, Malaysia

Most schemes in common use for field and laboratory classification of peats were developed in boreal and humid temperate regions and do not recognize the distinctive features and specific uses of tropical peats, such as those of the Tasek Bera Basin in tropical Peninsular Malaysia. The important aspects of peat texture (morphology of constituents and their arrangement) and laboratory ash content (residue after ignition) need modification to be valuable for classifying these and other tropical peat deposits. In the Tasek Bera Basin, most of the deposits would not be considered as peat according to some classification schemes, even though most have C contents >25%. We propose a new three-group (fibric, hemic, sapric) field texture classification applicable to tropical organic deposits, which is similar to the system of the US Soil Taxonomy. The classification is based on the following factors: (1) visual examination of the morphology of the peat constituents (texture); and (2) estimates of fiber content and matrix (finest fraction of peat consisting of highly humified organic matter and inorganic material). The classification is applicable to all organic deposits with 35% loss on ignition). We also present a new laboratory classification of organic soils based on ash and C content. The US Soil Taxonomy classifies organic soils as having more than 12–18% organic C, depending on clay content. Ash content and these limits for organic soils allow the discrimination of four main groups: peat, muck, organic-rich soil/sediment and mineral soil/sediment. Peat is defined as having an ash content of 0–55%, muck 55–65%, organic-rich soil/sediment 65–80% and mineral soil/sediment 80–100%. The peat class is further subdivided into very low ash (0–5%), low ash (5–15%), medium ash (15–25%), high ash (25–40%) and very high ash (40–55%) subclasses.

Fitting institutions to ecosystems: the case of artisanal fisheries management in the estuary of Patos Lagoon

This paper analyzes the problem of fit of environmental institutions to the conservation of fisheries CPRs and the maintenance of artisanal fisheries in the estuary of Patos Lagoon, southern Brazil. The analysis identified problems with the definition of boundaries and rights to fisheries resources and incongruities between rules and local environmental/resource conditions which can affect the sustainability of artisanal fisheries. The driving forces of misfits showed to be associated to internal and external factors including the weak and changeable institutional arrangements, socio-economic conditions, the regime structure of governance, and individual stewardship for resources.

Effect of pH on ammonium adsorption by natural Zeolite clinoptilolite

Abstract Clinoptilolite, a zeolite mineral with a high cation exchange capacity and surface area, has ion‐exchange properties that can be utilized to adsorb NH4 +, protecting it from losses during composting of N‐rich animal manures. Ammonium adsorption by the natural zeolite clinoptilolite was studied to ascertain the effectiveness of the zeolite as an NH4 + adsorbent at pH 4, 5, 6, and 7. The NH4 + adsorption data were fitted to the one‐ and two‐surface Langmuir, Freundlich, and Temkin isotherms. All models described the NH4 +adsorption data successfully (r2≥0.939). The one‐surface Langmuir, Freundlich, and Temkin were converted to pH‐dependent forms. The amount of NH4 + adsorbed increased as pH and initial NH4 +concentration increased. From the one‐surface Langmuir isotherm, the NH4 +adsorption capacity (Xm) of the zeolite increased linearly with pH (r2=0.994), and was estimated to be 9,660 mg N kg‐1 at pH4, 11,220 mg N kg‐1 at pH 5, 12,720 mg N kg‐1 at pH 6, and 13,830 mg N kg‐1 at pH 7. The adsorptio...

A comparison of methods to determine total, organic, and available phosphorus in forest soils

Abstract Several methods for the determination of soil phosphorus (P) in acidic forest soils were examined. The Parkinson and Allen digestion method removed more total P than did the ignition method, especially with mineral soils. There were problems with both the Saunders and Williams ignition method and the Bowman and Moir extraction protocol for organic P determination. The problems were more pronounced when used on organic soil samples The Bray P1 was better than the Mehlich 3 method for measuring available P in mineral soils.

Colorimetric determination of phosphorus in citrate‐bicarbonate‐dithionite extracts of soils

Abstract Existing colorimetric methods for determining phosphorus (P) in citrate‐bicarbonate‐dithionite (CBD) extracts from soils and sediments require pretreatments of extracts prior to the determination of the element. A method is proposed for the determination of P in CBD extracts without any chemical treatments. Maintaining the citrate concentration below 2.4 mM, maximum and stable absorbance develops in P‐Mo‐Sb system within one hour and remains stable for 20 hours. An evaluation of potential interference was made by adding varying amounts of P to CBD extracts over a range of extractable iron (Fe) and aluminum (Al) levels. Near 100 percent recovery of the added P suggests the applicability of the method to soils and sediments. Major advantages of the method are speed, simplicity, reliability and stability of the colored complex.

Virtual Water: A Framework For Comparative Regional Resource Assessment

New developments in water resource allocation techniques range from local management of green water to international trade in water. A further extension of this is through the virtual water concept, which is the water required to produce a crop or product. The virtual water content of many products is now available at a national and global scale. While these calculations are meaningful in international trade debates, they are not useful to water managers since regional climatic and management conditions are highly variable. The utility of the virtual water concept at a smaller scale is illustrated by a comparison of agricultural crops in the driest and wettest agro-climatic regions in Canada. Results were compared to national and international global calculations. The calculations are highly sensitive to local conditions, and locally collected data needs to be aggregated and compared in order to be made useful to water managers and land use planners.

A method for estimating organic-bound iron and aluminum contents in soils

Abstract Estimation of organic‐bound iron (Fe) and aluminum (Al) is an important diagnostic technique in pedology. The commonly used sodium pyro‐phosphate method yields somewhat ambiguous results and is inconvenient if an ultracentrifuge is not available in the laboratory. This study showed that 0.1M sodium nitrilotriacetate (NTA) could be used instead of pyrophosphate. The Fe and Al extracted by 0.1 M NTA were highly correlated to that by sodium pyrophosphate with R2 = 0.993 for Fe and R2 = 0.992 for Al, while the dissolution effects on standard mineral samples in NTA was kept at a minimum. NTA has the advantage of not requiring ultrafiltration, ultracentrifugation, or the addition of a flocculating agent as is the case for the pyrophosphate method.

Processes affecting surface and chemical properties of chrysotile: Implications for reclamation of asbestos in the natural environment

Holmes, E. P., Wilson, J., Schreier, H. and Lavkulich, L. M. 2012. Processes affecting surface and chemical properties of chrysotile: Implications for reclamation of asbestos in the natural environment. Can. J. Soil Sci. 92: 229-242. A landslide at the headwaters of the Sumas River in southwestern British Columbia, is a seasonal and episodic source of chrysotile asbestos to the floodplain soil. Fresh alluvial deposits of fibres have potential for aeolian movement, posing a health risk to the Sumas watershed population. To understand the effects aquatic and pedogenic processes have on the fibres, asbestos materials from the river and floodplain were subjected to organic acid treatments in the laboratory. Changes were monitored by X-ray diffraction, scanning electron microscopy and elemental analysis. Fibre surfaces modified by organic acid treatments were similar to those affected by natural processes in that they showed a high loss of elements from the brucite layer compared with the silica tetrahedral layer, and the surfaces became smoother due to the loss of a rough amorphous coating. To initiate sustainable reclamation practices, changes in fibre surfaces by natural processes need to be considered and enhanced by incorporation of organic amendments that produce complexing soil acids. Reclamation activities should focus on recently deposited sediment along the floodplain. Non-polluting organic material, such as peat, compost and sawdust could be applied to increase reaction potential and kinetics of the reaction of chrysotile with naturally occurring acids.

Short-range order mineral phases control the distribution of important macronutrients in coarse-textured forest soils of coastal British Columbia, Canada

Background and aimsSecondary minerals are known to provide sorption sites that contribute significantly to plant nutrient retention within the soil profile. The influence of mineral components on nutrient availability is however less certain in coarse-textured soils, where the abundance of clay minerals is low. The objective of this study is to identify important edaphic predictors of nutrient distribution in coarse-textured forest soils.MethodsWe measured base cations, nitrogen and phosphorus forms in the organic, mineral top- and subsoil horizons of podzols of southwestern Canada and investigated their relation to soil properties using simple and canonical correlation analysis.ResultsWe found that soil organic carbon and reactive aluminum and iron species were stronger predictors of nutrient distribution than the silt and clay content. In particular, short-range order (SRO) Al and Fe mineral phases were strongly correlated with the distribution of potassium and phosphorus. Preferential association of K with SRO phases likely contributed to K retention in the profile. Phosphorus sorption to SRO phases decreased the amount of available P. Contrary to generally expected geochemical behaviour, labile P was negatively related to pH. We attributed this anomalous relation to an increase in the proportion of strongly sorptive SRO Al and Fe phases at higher pH.ConclusionThis study shows that understanding the sorptive properties of naturally-occurring SRO Al and Fe species is important to our ability to predict nutrient availability and points to the need for further investigation of the geochemical behaviour of SRO mineral phases under field conditions.