Chloride accumulation vs chloride excretion: Phytoextraction potential of three halophytic grass species growing in a salinized landfill

Abstract

Phragmites australis, Puccinnellia nuttalliana (salt accumulators), and Spartina pectinata (salt excretor) were investigated based on their relative abilities to phytoextract chloride from a cement kiln dust landfill in Bath, ON. Salt tolerance mechanisms were found to affect phytoextraction performance. On the basis of accumulation alone, P. australis had the greatest phytoextraction efficiency compared to the other two species due to its high biomass (despite having the lowest shoot ion concentrations). Conversely, when weekly salt excretion on the leaf surfaces of S. pectinata was accounted for over an eight week period from July to August 2014, removal of Cl− increased by 160% surpassing the extraction ability of P. australis by nearly 60%. Energy dispersive spectroscopy analysis of the excreted salt particles on S. pectinata indicates that they were composed of the plant macronutrient, potassium and micronutrient, chloride. Wind re-distribution of these nutrients may actually have beneficial effects on the environment, as they are required by both plants and animals for various metabolic functions. This is the first study to demonstrate salt excretion for the remediation of an industrially salinized landfill in Canada.