Evaluating the Content of Petroleum Hydrocarbons in Plants Useful as Forage for Sheep in Patagonia, Argentina

FUCHS JULIO S.; GESINO, ALICIA; GUIRIN, ALEXIS

Mérida

Congreso; SETAC North America Focused Topic Meeting. Pollutants in the Environment: Fate and Toxicity.; 2011

SETAC North America

. Most of Argentina?s upstream oil industry develops in the arid ecosystems of Patagonia, mainly coex-isting with sheep farming. Occasionally, oil spills impact on soil and vegetation. The aim of this study was to evaluate the contents of petroleum hydrocarbons in forage plants and to further estimate the applicability of these parameters to predict the ingestion risk for sheep feeding in an area formerly affected by an oil spraying event. Three areas of high to low known vegetation impact after an oil well blow-out (respectively Area 1, Area 2 and Area 3) and a control area were selected for the study. Aerial parts were collected from two plant species consid-ered as of forage relevance for sheep. Hydrocarbon content in the vegetal biomass was analyzed by several methodologies: Total hydrocarbons (THC) using tet-rachloroethylene as extraction solvent (EPA 3540C/413.2) (Method 1); THC extracts of Method 1 with a previous silica gel clean-up step (EPA 3540C/418.1) (Method 2); THC by GC-FID method with the same method 2 preparation process (EPA 8015, C10-C32) (Method 3); THC by GC-FID with a saponifi-cation step and florisil clean-up (Method 4); Polycyclic aromatic hydrocarbons (PAHs) (Saponification/Florisil/GCMS) (Method 5); with the addition of the analysis of some known risk metals (Mexican NOM-117-SSA1-1994). THC analyzed by all methods showed the same trends, with relatively higher values for method 1. Results for THC contents by chromatographic methods 3 and 4 ?sup-plied? broadly similar values for all samples studied, indicating for the one hand that there is no observable difference between the two methods of cleaning and quantifying. Area 2 samples essentially showed no significant difference from the Control Site results, while Area 1 samples effectively showed deviations from the control site?s in both vegetal species studied (differences between 5 to 10 times the control value). All PAHs analyzed in plant tissues resulted below the limit of quantification of the method. Metals studied showed no significant differences between tissues from the control sector and from the other areas assessed. From the results obtained, it was possible to differentiate biogenic from petrogenic HCs in plants, a useful methodology to obtain total HC content in forage veg-etation, and consequently, practical parameters could be established to assess the risk for sheep of high regional economic interest in Patagonia, Argentina.