Emission of Nsub 2 from Polycyclic Aromatic Hydrocarbons Contaminated Soil at Different Water Contents Added with Vermicompost

• Published in: Compost science & utilization Vol. 17; no. 1; pp. 48 - 54
• Main Authors: Alvarez-Bernal, Dioselina, Contreras-Ramos, Silvia M, Montes-Molina, Joaquin A, Van Cleemput, Oswald, Dendooven, Luc
• Format: Journal Article
• Language: English
• Published: 01.12.2009
• ISSN: 1065-657X

Vermicompost is typically applied to improve soil quality, but can be used to remediate hydrocarbon-contaminated soils. Little information is available on how contamination and subsequent bioremediation with vermicompost affects emissions of Nsub 2 and CO2, important greenhouse gases. A sandy loam soil with different water contents (40%, 60%, 80% and 100% of water holding capacity (WHC)) was contaminated with phenanthrene, anthracene and benzo(a)pyrene and amended with or without vermicompost to stimulate remediation of soil. Emissions of Nsub 2 and CO2, and concentrations of inorganic N (ammonium (NHsub 4sup +), nitrite (NOsub 2sup -) and nitrate (NOsub 3sup -)) were determined in a laboratory incubation experiment after 0h, 5h, 24h, 72h and 168h. The cumulative CO2 production rate was significantly larger in soil incubated at 60% WHC and 80%WHC compared to soil incubated at 40% and 100%WHC. Addition of vermicompost increased production of CO2 and Nsub 2. Addition of PAHs increased production of CO2 when water content of soil was at 60% WHC and production of Nsub 2 when water content of soil was at 80% WHC. Addition of PAHs induced immobilization of inorganic N and inhibited nitrification as the concentration of NHsub 4sup + and NOsub 2sup - in soil contaminated with PAHs was larger than in unamended soil while the concentration of NOsub 3sup - was lower. It was found that contamination of soil with PAHs increased emissions of Nsub 2 and CO2 and biostimulation of autochthonous microflora with organic material to remediate those soils further increases production of Nsub 2 and CO2. These findings indicate that trace gas emissions should be included in estimations of the environmental impact of contamination of soil and their subsequent bioremediation. [PUBLICATION ABSTRACT]