The creation of novel methodologies to examine the effects of phosphorus amendments on petroleum hydrocarbon bioremediation

Successful soil petroleum hydrocarbon (PHC) bioremediation demands adequate phosphorus (P) concentrations. However, rapid adsorption and precipitation processes in calcareous soils lower labile soil P concentrations. As the P form impacts bioavailability, we hypothesized that the P amendment form would influence PHC degradation rates. However, soil characteristics, large Pi concentrations and inefficient P soil extractions limit the ability to reveal P amendment effects. Therefore, new methods, including analytical techniques and a generalized linear mixed model (GLMM), were created to investigate amendment fate and efficiency. The initial two studies focused on improving P analytical investigations. The first experiment created a stable isotope probing method using labelled (18O)-phosphate to monitor soil P dynamics. Soil received either unlabelled or labelled phosphate to monitor P transformations via sequential fractionation pools over six weeks. Since the unlabelled phosphate species is indistinguishable from endogenous soil P (94-144% of total soil P (Pt)), the mass balance of the 18O-labelled phosphate was more precise (67-85% Pt). As the role of subsoil organic P (Po) during PHC bioremediation is unknown, the second study aimed to improve P recovery from calcareous subsoils. After investigating pretreatments to a sodium hydroxide - ethylenediaminetetraacetic acid (EDTA) extraction, sodium acetate recovered the largest concentration of P from Po-doped calcareous subsoils (5.6% Pt) compared to other tested schemes (3.5-4.8% Pt). However, EDTA hindered MS Po quantification. While the analytical methodologies provide opportunities to speciate P and movement, it is not known whether the P bioavailability impacts PHC bioremediation. The final study investigated the influence of P amendments in low-activity (stalled) PHC-contaminated soils. A GLMM isolated the preferred environmental conditions for PHC removal in four sites. Predictions revealed benzene degradation increased as soil magnetic susceptibility and EC increased; however, this relationship is inversed for soil pH. Three fertilizer amendments (Na-phosphate, triethyl phosphate, and tripolyphosphate (TPP)) were delivered to low-activity soils to validate predictions. For one tested soil, TPP stimulated PHC removal; however, the other samples did not respond to any P amendments. The combination of novel analytical methodologies and a model-microcosm study provides new opportunities to elucidate the cycle of the macronutrient in PHC-contaminated calcareous subsoils.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Soil Science

Grantor

University of Saskatchewan

Year dc:date.issued

2023

Author dc:creator

• Schryer, Aimee D

Advisor dc:contributor.advisor

• Siciliano, Steven D

Committee members dc:contributor.committeemember

• Peak, Derek
• El-Aneed, Anas
• Cade-Menun, Barbara
• Schoenau, Jeff
• Schneider, Kimberley

• phosphorus
• petroleum hydrocarbons
• bioremediation

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10388/15136

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/15136