An Evaluation of Extractants for Assessment of Metal Phytoavailability to Guide Reclamation Practices In Acidic Soilscapes In Northern Regions

Fri

1 Jan 2010

An Evaluation of Extractants for Assessment of Metal Phytoavailability to Guide Reclamation Practices In Acidic Soilscapes In Northern Regions

Authors: Joinal Abedin^a , Peter Beckett^b and Graeme Spiers^abc

^aCentre for Environmental Monitoring, MIRARCO, ^c Department of Chemistry and Biochemistry and ^cDepartment of Earth Sciences, and ^bc Department of Biology, Laurentian University, 935 Ramsey Lake 6 Road, Sudbury, Ontario. P3E 2C6, Canada

Abstract:

Although soil organic matter and nutrient bioavailability in metal impacted soilscapes of Sudbury, Ontario are potentially limiting full ecological recovery, total metal content was used as the critical driver for a 2008 ecological risk assessment. The current greenhouse study evaluated chemical extractants to predict bioavailability of nutrients and contaminant metals to indigenous grasses (Deschampsia). Single extraction methods (0.01M strontium nitrate, water, 0.01M calcium chloride, 0.1M sodium nitrate, 1.0M ammonium nitrate, 0.1M lithium nitrate, 1.0M magnesium chloride, 0.11M acetic acid, 1.0M ammonium acetate, 0.05M ammonium-EDTA, pore water) were examined to assess availability of potentially phytotoxic metals and nutrients in smelter impacted soils. Extraction procedures to predict phytoavailability were either soil concentration or plant tissue concentration and element dependent. Total and extractable metal concentrations were more correlated for regional contaminant metals (e.g., copper, lead, arsenic, selenium) released by the smelting industry than non19 contaminant ones (e.g., iron, calcium, potassium, boron, zinc, molybdenum). The lack of relationship between total and extractable concentrations for most non-contaminant metals suggests total concentration is not a good indicator of phytoavailability for nutrient elements. Stronger correlations between shoot tissue and extractable concentrations were observed for less aggressive extractants (pore water, water, lithium nitrate) reflecting their suitability in predicting phytoavailability over most aggressive ones (except ammonium nitrate).