BIOMONITORING AND ASSESSMENT OF AIRBORNE FLUORIDE FROM FERTILIZER PRODUCTION

• Author / Creator

  Zhao, Yihan

• Phosphogypsum (PG) is an acidic by-product created during phosphate fertilizer production (Rutherford et al 1994). In open or operational PG stacks, airborne fluorides are emitted from phosphogypsum process water pond surface evaporation or particulate fluoride that can be transported as fluoride containing dust. This two year research project aimed to improve the understanding of effects of airborne fluoride on plants. Various plant species were sampled in the vicinity of the Agrium Redwater PG stack since 2008 throughout the growing season. In 2015 and 2016, a biomonitoring system was developed to standardize greenhouse cultivation, field exposure and plant harvest. Lolium perenne L. (perennial rye grass) was selected as a bioindicator and exposed in different locations surrounding the emission source. Biomass was harvested for fluoride analysis. Distance from the source had the greatest influence on internal fluoride accumulation of perennial rye grass, followed by exposure time, then wind direction. Internal fluoride concentrations in perennial rye grass decreased exponentially with distance from the source, with a sharp drop within 500 m. Although age had no significant impact on internal fluoride accumulation of perennial rye grass, with longer exposure there were greater differences among three ages of plants. Wind direction may have considerable impacts on internal fluoride concentrations in perennial rye grass, with effect becoming weaker with the increasing distance from the source. From long term monitoring, the monthly pattern of total fluoride in forage was consistent year by year, peaking in fall. Concentration of soluble fluorides in PG ponds, air temperature and precipitation may contribute to total fluoride variation in forage over time. The latter two may have significant impacts on external fluoride accumulations. On average 32.3 % of total fluoride can be washed off plans biomass, approximation amount of external fluoride, and indicating that most fluoride in forage was internal. Biomonitoring can be a cost effective approach for detecting long term environmental impacts of airborne pollution and this research can be applied as a standardized biomonitoring method for airborne fluoride with plant species for Alberta which can be used in various reclamation and management scenarios.

• Subjects / Keywords

  • Biomonitoring
  • Phosphogypsum
  • Airborne Fluoride

• Graduation date

  Spring 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3DZ03D6R

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.