Dynamics of nitrogen in a PAHs contaminated soil amended with biosolid or vermicompost in the presence of earthworms Original Research Article

Nitrogen mineralization in PAHs contaminated soil in presence of Eisenia fetida amended with biosolid or vermicompost was investigated. Sterilized and unsterilized soil was contaminated with PAHs, added with E. fetida and biosolid or vermicompost and incubated aerobically for 70 days, while dynamics of inorganic N were monitored. Addition of E. fetida to sterilized soil increased concentration of image 100 > mg N kg−1, while concentrations in unsterilized remained <60 mg N kg−1 except for soil amended with biosolid plus PAHs where it increased to >80 mg kg−1. Addition of PAHs had no significant effect on concentration of image compared to the unamended soil, except in the soil added with biosolid. Addition of E. fetida to sterilized soil increased concentration of image 15 > mg N kg−1 while concentrations in unsterilized soil remained <7.5 mg N kg−1 except for soil amended with biosolid where it increased to >20 mg kg−1. Addition of PAHs had no significant effect on concentration of image compared to the unamended soil. Addition of biosolid and vermicompost increased concentration of image, while addition of E. fetida decreased concentration of image in biosolid amended soil. It was found that image and image oxidizers were present in the gut of E. fetida, but their activity was not sufficient enough to inhibit a temporarily increase in concentrations of image and image. Contamination with PAHs induced immobilization of N in biosolid or vermicompost amended soil, as did feeding of E. fetida on biosolid or vermicompost.