Soil analysis procedures using 0.01 M Calcium Chloride as extraction reagent
ABSTRACT This publication gives details of laboratory procedures for the determinations of bioavailable (e.g., plants) quantities of nutritional and polluting inorganic elements in 0.01 M CaCl2 extracts of air‐dry soil samples. Air‐day soil samples are extracted for two hours with a 0.01 M CaCl2 solution of 20°C in a 1:10 extraction ratio (W/V). After measuring the pH in the settling suspension, the concentrations of nutritional and polluting elements are measured in the clear centrifugate or filtrate. The procedure is simple, easy to perform, and cheap (labor, chemicals) in daily use in routine soil laboratories. The method receives internationally more and more attention as an alternative for the many extraction procedures for a single nutrient or pollutant that are still in use nowadays. The soil is extracted with a solution what has more or less the same ionic strength as the average salt concentration in many soil solutions. Various nutrients and metals can be measured in a single extract that allows considering relationships between them during interpretation of the data. For most elements, different detection techniques are described in detail in this publication. Detailed laboratory procedures are described for the determination of pH, total dissolved organic carbon, nitrate, ammonium, total dissolved nitrogen, sulphate, total dissolved sulfur, ortho‐phosphate, total dissolved phosphate, sodium, potassium, magnesium, cadmium, copper, nickel, lead, aluminum, iron, arsenic, boron, and phenols. Since only one extract of soil samples is used, profitable use can be made of multi‐element detection techniques like segmented‐flow analysis spectrometry, ICP‐OES, and ICP‐MS.
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ABSTRACT: Purpose The present research aimed to assess the influence of two phosphorous (P) amendments on metal speciation in rhizosphere soil and the soil–plant transfer of metals. Materials and methods Complementary experiments were performed: field experiments on a contaminated cultivated soil and laboratory experiments on an uncultivated contaminated soil to highlight the mechanisms involved in metal-phosphorous interactions. In laboratory experiment, P amendments were added at 120 mg P/kg of soluble KH2PO4 amendment and 9,000 mg P/kg of solid Ca5(PO4)3OH amendment. Results and discussion Field-culture results showed the possible food-chain contamination due to Pb, Cd, Cu, and Zn phytoaccumulation by pea and mustard plants from a cultivated agricultural soil. Moreover, P-metal complexes were observed by microscopy in the rhizosphere soil. In laboratory experiments, the application of P amendments significantly increased Pb and Zn level in rhizosphere soil compared to control. Phosphate amendments significantly increased metal-P fraction and decreased “oxides” and “organic matter” fractions of Pb and Zn. Soluble-P amendment was more effective than solid P amendment in changing Pb and Zn speciation. The changes in metal speciation are higher in the rhizosphere soil of pea than tomato. Application of P amendments increased Pb and Zn TF root/soil but decreased TF shoot/root. Conclusions The effectiveness of in situ metal immobilization technique varies with the type and quantity of applied P amendment as well as plant and metal type.Journal of Soils and Sediments 04/2014; · 1.97 Impact Factor
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ABSTRACT: Chemical stabilization is a cost-effective, environmentally friendly, in situ remediation technology based on the application of organic and/or inorganic amendments to reduce soil metal bioavailability. Our objective was to assess the early short-term effects of organic amendments (sheep manure—SHEEP, poultry litter—POULTRY, cow slurry—COW, paper mill sludge mixed with poultry litter—PAPER), in sterilized and non-sterilized form, on the microbial and chemical properties, as well as on the phytotoxicity, of a Cd, Pb and Zn contaminated soil. Our results provide useful information regarding (1) the effectiveness of amendments for chemical stabilization of mine soil and (2) the impact of microbial populations present in the amendments on soil native microbial communities. Microbial populations present in the amendments did not substantially modify soil microbial functional diversity, as reflected by Biolog EcoPlates™ data, except for PAPER-amended soils.We observed a good correlation between lettuce root elongation (phytotoxicity bioassay) and Cd, Pb, and Zn CaCl2-extractable concentrations in soil. SHEEP and PAPER amendments were particularly effective at increasing soil pH and reducing metal bioavailability and phytotoxicity, while POULTRY and COW led to higher values of soil microbial properties (respiration and functional diversity). Beneficial effects observed under POULTRY at the beginning of the experiment, due to the presence of easily degradable organic matter, were partially lost over time. Our results emphasize the importance of the early monitoring of soil properties (microbial and chemical) and phytotoxicity to properly identify bottlenecks during amendment selection for chemical stabilization, in terms of reduction in metal bioavailability and improvement in soil health.Water Air and Soil Pollution 01/2014; 225:1863. · 1.75 Impact Factor
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ABSTRACT: Chemical stabilization is a soil remediation technique based on the incorporation of organic and/or inorganic amendments to metal contaminated soil in order to decrease metal bioavailability and improve soil quality. Consequently, the establishment of follow-up monitoring programmes is essential to ensure the long-term effectiveness of chemical stabilization in terms of both metal bioavailability reduction and soil quality improvement. In this study, three doses (20, 40 and 80 t ha−1) of a lime-treated sewage sludge, that meets legal standards regarding metal contents, were added to a metalliferous mine soil and a variety of physicochemical and microbial indicators of soil quality were measured over time (immediately before treatment application and one and six months after such application). Soil CaCl2-extractable and plant metal concentrations were also measured. We carried out a complementary interpretation of soil microbial properties through their grouping within a set of ecosystem attributes of ecological relevance: vigour, organization, stability, suppressiveness and redundancy. Sewage sludge addition led to an increase in soil pH, but this beneficial effect was transient. The addition of sewage sludge had a more pronounced effect on parameters used here to estimate soil vigour (dehydrogenase activity, basal and substrate-induced respiration). On the contrary, the addition of sewage sludge did not significantly alter the composition of soil microbial communities, as reflected by PCR-DGGE data. Chemical stabilization was only partly successful: it did improve soil quality but the expected reduction in soil metal bioavailability (as reflected by the values of CaCl2-extractable metal concentration) was clearly observed only for Cd (not for Pb or Zn); however, SL addition led to a significant reduction in shoot metal concentration for the three metals under study. The assessment of soil quality at the attribute level has proven useful for the interpretation of the effect of chemical stabilization on soil functioning.Applied Soil Ecology 01/2014; 75:1–12. · 2.11 Impact Factor