Nutrient enhanced biodegradation of crude oil in tropical salt marshes

Tropical salt marshes in Louisiana are at risks of accidental oil spills an d remediation of these ecosystems is mainly limited to natural biodegradati on due to physical sensitivity of the ecosystems. This study investigated b oth intrinsic and nutrient enhanced rates of crude oil degradation in core studies. In addition, loading rates of nitrogen and optimal porewater nitro gen concentrations were determined. Nitrogen additions increased biodegrada tion rates of some alkanes and polycyclic aromatic hydrocarbons (PAHs). Add ition of NH4+-N increased zero-order mineralization constants of labeled he xadecane and phenanthrene up to 15.4-19.2% (Fourchon marsh) and 56.2% (Ugly Shack Bayou marsh) and rates of total carbon dioxide production up to 14.0 -33.1% (Fourchon marsh) and 3.0% (Ugly Shack Bayou marsh), respectively. Ef ficient biodegradation of crude oil was achieved when NH4+ was applied at t he loading rate of 28.3-56.6 g N m(-2) producing porewater concentration at the level of 80-450 mg NH4+-N L-1. No significant lag time was observed in dicating that nitrogen application directly stimulates biodegradation of cr ude oil in tropical salt marshes in Louisiana.