Geospatial Synthesis of Biogeochemical Attributions of Porphyrins to Oil Pollution in Marine Sediments of the Gulf of México

Abstract

Porphyrins are highly persistent in the environment and represent a helpful biogeochemical attribute to assess the spatial distribution of the effects of oil spills on ecosystems and their resilience. In areas prone to natural and human-originated oil spills, the measurement of VO– and nickel–porphyrins in marine–sediment samples can identify the effects of oil pollution across spatiotemporal scales. The goal is to explore whether or not these compounds can be useful indicators of the geospatial attributions of oil contamination in the surficial sediments. We hypothesize that the geospatial gradients of porphyrins in marine sediments from petroleum spills and seepage activities—related to traditional indices of oil pollution, such as heavy metals and polycyclic aromatic hydrocarbons—can be identified in small sediment samples and concentrations. The objectives are two-fold: (1) extract and measure VO– and nickel–porphyrins from small marine sediment samples using high-pressure liquid chromatography, and (2) use cluster analysis and the canonical correlation analysis to identify the biogeochemical and geospatial attributions between VO–porphyrins and another index of oil pollution extracted and analyzed from sediments of the Campeche Shelf, in the Gulf of Mexico. High-pressure liquid chromatography with diode array detectors, two inverse phase columns and an isocratic separation method, was used to analyze the marine sediments. We identified 5.1 ng/g to 240.3 ng/g to VO–porphyrins concentrations with gradients toward areas identified as potential sources of oil pollution. Similar patterns were present for nickel–porphyrins, with values two orders of magnitude below those for the VO–porphyrins. The results represent a valuable opportunity to measure the biomarkers associated with oil pollution in small sediment samples. Furthermore, the results can find the potential drawbacks of benthic ecosystem resilience.