Retention and partitioning of polycyclic aromatic hydrocarbons in Sarcocornia fruticosa from two Portuguese salt marshes

Abstract

Sixteen PAH compounds (containing three to six rings) were quantified in sediments from the Rosário and Mitrena salt marshes in the Tagus and Sado estuaries, respectively, colonized by Sarcocornia fruticosa, and in belowground and aboveground plant tissues. Sediments from Rosário presented higher PAH concentrations (0.83–8.71 µg g^–1) than those from Mitrena (0.22–1.63 µg g^–1). Levels in belowground plant tissues showed a pronounced contrast between the two marshes: 84–165 and 0.15–0.43 µg g^–1, respectively. Belowground material in contaminated layers contained 9–55 times more PAHs than sediments, while ratios lower than one were obtained in lower contaminated layers. Five- and six-ring compounds predominated (60–75%) in sediments and belowground plant material from both sites. Aboveground plant tissues presented no differences in PAH concentrations (0.17–0.18 ng g^–1) and composition in both marshes, only three- and four-ring compounds being detected. This narrow concentration range appears to indicate that atmospheric deposition is the predominant pathway of PAH accumulation in aerial plant tissues.