Physiological Response of Populus balsamifera and Salix eriocephala to Salinity and Hydraulic Fracturing Wastewater: Potential for Phytoremediation Applications.

Michael A Bilek,Robert D Guy,Shawn D Mansfield,Raju Y Soolanayakanahally

doi:10.3390/ijerph17207641

Abstract

Natural and anthropogenic soil degradation is resulting in a substantial rise in the extension of saline and industrially-polluted soils. Phytoremediation offers an environmentally and economically advantageous solution to soil contamination. Three growth trials were conducted to assess the stress tolerance of native Canadian genotypes of Populus balsamifera L., Salix eriocephala Michx., and one hybrid willow (S. discolor × S. dasyclados) to salinity and hydraulic fracturing (fracking) wastewater. Thirty-three genotypes were grown in NaCl or fracking wastewater solutions between 0 and 7 mS−1 over a period of 3–4 months. P. balsamifera was observed to be relatively salt-intolerant compared to S. eriocephala and hybrid willow, which is likely caused by an inability of P. balsamifera to restrict Na+ translocation. Photosynthesis and transpiration decreased with salinity treatments, and severe reductions occurred with exposure to fracking solutions. Raffinose and stachyose content was tripled in leaf and root tissues. In willows, Na+ was primarily confined to root tissues, Cl− accumulated up to 5% dry weight in leaves, and K+ was translocated from roots to leaves. Willow genotypes CAM-2 and STL-2 displayed the greatest maintenance of growth and resistance to necrotic symptoms in all trials, suggesting that these genotypes may be useful for practical application and further field study.

Highlights

At present, the available arable land is rapidly declining worldwide due, in part, to increased salinity arising from both natural and anthropogenic sources, such as agriculture and oil and gas exploitation activities [1,2,3,4]
In the first salinity trial, clear differences were apparent in the salinity tolerance of balsam poplar compared to willow stecklings, as demonstrated by their growth and survival during eight weeks growth at either 0, 30, and 80 mM NaCl
Grand Prairie (GPR)-10 and LOR-5 were chosen to compare their relatively poor patterns differed between the two species, but a sharp difference in tolerance was very apparent in their growth when subjected to salt treatment

Summary

Introduction

The available arable land is rapidly declining worldwide due, in part, to increased salinity arising from both natural and anthropogenic sources, such as agriculture and oil and gas exploitation activities [1,2,3,4]. Current methods of mechanical and chemical remediation of disturbed soils are prohibitively expensive, laborious, and disruptive to the local ecology. Bioremediation is a less invasive alternative to chemical and mechanical remediation that typically employs the natural processes of microorganisms and fungi to degrade waste [5,6]. Phytoremediation is the process of improving soil quality using plants via contaminant degradation, stabilization, accumulation, filtration (such as through a constructed wetland), or volatilization. A range of plant species have been identified for potential use in

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