Concentration of Alkane and Aromatic hydrocarbons in south Louisiana marshes 2010 to 2012

We collected 388 surface sediment samples from Louisiana coastal wetlands during May 2010 (31), September 2010 (64) and February 2011 (30), May 2011 (87), September 2011 (66), June 2012 (22), August 2012 (30), September 2012 (30), and October 2012 (28) (Figure 1). The majority of the samples were collected within 10 m of the shoreline. Others were collected every 20 m along eight 90 m transects in June 2011, and five 100 m transects in September 2011. These transects were perpendicular to the wetland/water interface. Sediment samples were collected as a composite sample of the upper 5 cm and refrigerated until analysis. Samples from February 2011 were collected at 30 sites and re-sampled within 50 cm of the February 2011 sites in August 2012 and September 2012. The primary emergent vegetation was Spartina alterniflora and Juncus sp. with minor amounts of Schneoplectus americanus. The wetland type is commonly known as a salt marsh.