MODELING OF POTENTIAL HYDROCARBON CONTAMINATION OF GROUNDWATER FROM PETROLEUM PRODUCTION IN LORETO REGION, NORTHERN PERU

The Loreto Region of northern Peru has been the site of considerable recent petroleum exploration and production. Due to the deterioration of poorly maintained pipelines, there have been significant petroleum spills, especially in the watersheds of the Corrientes, Maranon, Pastaza, and Tigre Rivers. The objective of this study has been to create a model for predicting the likelihood that the effects of a petroleum spill in these watersheds will reach groundwater by comparing the residence time in soil with the time required for microbial degradation. A custom MATLAB script included linear partitioning of multiple organic compounds among the water, air, soil and NAPL phases. The three organic compounds considered were anthracene, benzene, and naphthalene. Soil parameters for the four watersheds were obtained from the FAO/UNESCO Soil Map of the World. Residence time half-lives were calculated for depths of penetration of the initial spill ranging from 0.1-5 m. All residence time half-lives were lowest for the Tigre watershed (dominated by loamy sand textures) and highest for the Corrientes watershed (dominated by clay textures). Over the entire parameter space, residence time half-lives ranged from 1.5‑305.0 years for benzene, 28.6-5848.7 years for naphthalene, and 564.1-115,360.0 years for anthracene. Comparing with typical biodegradation half-lives of 10-730 days for benzene, 1‑258 days for naphthalene, and 199-252 days for anthracene, it can be seen that penetration to groundwater is unlikely for naphthalene and anthracene, but is a distinct possibility for benzene, especially in the Tigre watershed. Further results will be reported at the meeting.