Bioremediation: Application of slow-release fertilizers on low-energy shorelines

Abstract

In situ biodegradation, the activation of microbial processes capable of destroying contaminants where they are found in the environment, is a biological process that responds rapidly to changing environmental factors. Accordingly, in situ sediment enclosures were used to test the efficacy of selected nutrient formulations to enhance the biodegradation of a waxy crude oil in a low-energy shoreline environment. The addition of soluble inorganic fertilizers (ammonium nitrate and triple superphosphate) and slow-release nutrient formulations (sulfur coated urea) stimulated microbial activity and prolonged the period of oil degradation, despite a decline in seasonal temperatures. Low temperatures reduced the permeability of the coating on the slow release fertilizers, effectively suppressing nutrient release. Of the nutrient formulations evaluated, we recommend the application of granular slow-release fertilizers (such as sulfur-coated urea) when the overlying water temperatures are above 15o C, and the application of soluble inorganic fertilizers (such as ammonium nitrate) at lower temperatures. Comprehensive analysis of the experimental results indicate that application protocols for bioremediation (form and type of fertilizer or type and frequency of application), be specifically tailored to account for differences in environmental parameters (including oil characteristics) at each contaminated site.