Plant Toxicity Study for Boron in Peat/Muskeg Ecosystems

Tony Knafla, Equilibrium Environment Inc.
GL 09-9157-50

Muskeg and associated peat soils form a significant portion of Canada’s northern ecosystem. Boron is a common co-contaminant with produced water, and is thus highly relevant to salt releases in these muskeg / peat ecosystems. While salts such as chloride are essentially non-sorptive and highly mobile, the sorption properties of boron are especially significant in peat and strongly influence transport and toxicity. The standard ‘hot-water soluble’ (HWS) analytical protocol upon which the Alberta Tier 1 boron guidelines are based may be especially unsuitable for muskeg ecosystems where sorption is high and toxicity to plants may be significantly reduced. In some cases, background concentrations may potentially exceed Tier 1 guidelines by several-fold while still posing minimal environmental risk. The proposed study would perform plant toxicity studies according to Environment Canada protocol using a suite of muskeg species. The soils used would be a combination of field-impacted peat soil along with laboratory-spiked peak soils. Boron concentrations would be characterized both by HWS boron as well as saturated paste boron, a promising analytical method for potentially predicting plant toxicity and distinguishing between natural background levels and anthropogenic impacts. This study would expand upon and synergize with a current (2010) study of boron toxicity toward agricultural species in mineral soils being performed by Equilibrium Environmental in conjunction with Exova. The proposed 2011 study would also be performed in conjunction with Exova, and would continue to leverage Equilibrium’s significant experience with boron risk assessments and field and lab toxicity studies.

Industry would benefit from this project in terms of reduced investigation and remediation costs as well as improved environmental performance. In some cases, natural background levels of boron in muskeg may exceed guidelines and trigger unnecessary remediation at significant financial cost and environmental disruption. When anthropogenic impacts truly are present, the improved understanding of boron toxicity in muskeg would allow more efficient, risk-based remediation efforts than the current Tier 1 guidelines allow. Ultimately, revisions to existing guidelines would ideally be possible as a result of this study. An improved understanding of boron sorption and toxicity in muskeg may also suggest novel remediation techniques such as targeted boron sorption by peat.

Policy Issue
Additional Science for the Refinement of Regulatory Guidelines/Directives/Policies/Criteria. Natural versus anthropogenic Impacts.

Knowledge Gap
Development of risk-based environmental assessment and remediation guidelines for salt releases to muskeg and other wetland settings, and evaluation of effective and appropriate remediation strategies. Update and development of risk-based, soil quality and remediation guidelines for boron.

DRAFT Boron Tier 1 Guideline Document
DRAFT Boron Tier 1 Supplemental Data Appendices
2015 AER_DRAFT Soil Remediation Boron