Combining diesel-contaminated soil and anhydrous ammonia-contaminated soil to measure the effectiveness of total petroleum hydrocarbon remediation

Roberts, T. L.; Hattey, J. A.

Currently, land-farming is the most widely used remediation technique for petroleum-contaminated soils. The major economic input associated with land-farming is the application of nitrogen fertilizer to enhance biodegradation. Previous research has shown that high concentrations of NH (sub 4) (super +) (>5000 mg kg (super -1) ) and/or petroleum hydrocarbons (>13000 mg kg (super -1) ) have a negative effect on biological activity and growth (Hutchinson, Banks, and Schwab, 2001). Soils with high concentrations of either NH (sub 4) (super +) or petroleum hydrocarbons are often barren and pose a major risk of contamination moving off-site due to uncontrolled erosion (Riser-Roberts, 1998). The purpose of this investigation was to determine the viability of utilizing anhydrous ammonia-contaminated soil as the primary nitrogen source for indigenous microorganisms in a diesel-contaminated soil. The nitrogen-contaminated soil was obtained from an anhydrous ammonia pipeline break and a soil with similar physical properties (texture and organic matter) was contaminated with 20000 mg kg (super -1) of diesel. Anhydrous ammonia-contaminated soil was applied as a fertilizer amendment at rates of 0, 230, and 450 kg ha (super -1) . Treatments were maintained for sixteen weeks with sampling dates at 0, 1, 3, 12, and 16 weeks. Concentrations of inorganic nitrogen (NH (sub 4) (super +) and NO (sub 3) (super -) ) and Total Petroleum Hydrocarbons (TPH) were collected at each sampling date. A significant difference in the rate of remediation was discovered between the 0 kg ha (super -1) N treatment and the 450 kg ha (super -1) N treatment. Initial TPH concentrations in the 450 kg ha (super -1) N treatment were reduced by as much as 14% over the 0 kg ha (super -1) N treatment in the first three weeks of remediation. Anhydrous ammonia-contaminated soil is a justifiable fertilizer treatment for the biodegradation of TPH contaminated soil and an effective means of remediating two soils simultaneously.