Nutrient amendments for contaminated peri-glacial soils: use of cod bone meal as a controlled release nutrient source

The lack of available nutrients, particularly nitrogen, often limits the rate of microbial petroleum hydrocarbon degradation in contaminated cold region soils. Microbial activity in many peri-glacial soils responds to addition of nitrogen, although excess levels can inhibit biodegradation by decreasing soil water potentials. Aqueous soluble inorganic fertilizer quickly partitions into soil water, increasing the salt concentration, and imposing an osmotic potential. Strategies that can be used to avoid microbial inhibition include the use of controlled release fertilizers. We studied the use of an organic fertilizer, cod bone meal, as a nutrient source for bioremediation. Nitrogen mineralization from cod bone meal was greater at 20 °C (first-order reaction rate constant k=0.0206 d−1) than at 10 °C (k=0.0154 d−1) and greater at pH 6.5 and 7.5 (k=0.0208 and 0.0189 d−1, respectively) than at pH 5.5 (k=0.0143 d−1). Net O2 consumption from diesel fuel degradation in a contaminated soil was greatly increased by addition of nitrogen and phosphorus in the form of diammonium phosphate (DAP) or cod bone meal relative to unfertilized soil. Cod bone meal fertilized soils had greater net O2 consumption than DAP fertilized soils. However, residual soil hydrocarbon analyses indicated no difference in petroleum loss between the two nutrient sources.