Rate of Turnover and Attenuation of Crude Oil Added to a Louisiana Sagittaria lancifolia Freshwater Marsh Soil C.W. LINDAU*, R.D. DELAUNE & I. DEVAI Wetland Biogeochemistry Institute, Louisiana State University, Baton Rouge, LA 70803-7511, USA The effects of nitrogen (N), phosphorus (P) and plants on attenuation of applied South Louisiana Crude (SLC) to a Sagittaria lancifolia freshwater marsh were investigated under field conditions. Sixteen plots were established in the substrate and treatments were: (1) oil, no plants, no N and P; (2) oil, plants, no N and P; (3) oil, no plants, N and P and (4) oil, plants, N and P. SLC, N and P were applied, 2 l m 2 , 10 g m )2 and 4 gm )2 , respectively. Sediment cores were collected 2, 15 and 53 weeks after oil application and extracts were analyzed by GC/MS for target n-alkanes and polycyclic aromatic hydrocarbons (PAH). Results demonstrate N, P and S. lancifolia accelerated turnover or attenuation of SLC at 2 and 15 weeks. However only trace hydrocarbon concentrations were detected in the marsh soil after 1 year regardless of treatment, demonstrating relative rapid turnover at the oil rate used in this study. Ó 2003 Elsevier Ltd. All rights reserved. Keywords: Oil spill, biostimulation, phytoremediation, oil migration, freshwater marsh Introduction Coastal marshes of Louisiana make up some of the most extensive wetlands within the United States. Freshwater and saltwater marshes in the State of Louisiana, account for about 27% of coastal marshes in the continental United States (Field et al., 1991). Marshes of the Mississippi River Deltaic Plain contain the largest salt marsh and second largest fresh marsh in the United States. LouisianaÕs Barataria and Ter- rebonne estuaries contain approximately 430,000 ha or 77% of marshes located within the Mississippi River Deltaic Plain (Visser et al., 1998). These wet- lands provide habitats and feeding areas for wild- life and fish, reduce coastal erosion and support important water quality functions (Mitsch & Gosse- link, 1994). Louisiana ranks fourth in crude oil production with only Alaska, Texas and California producing more. Louisiana state onshore and offshore production ac- counted for 100 million barrels and federal offshore Gulf of Mexico (Louisiana) production was estimated at 245 million barrels in 1994 (DOE/EIA, 1995). Nearly 20% of the nationÕs crude oil moves through LouisianaÕs coastal marshes (Davis & Guidry, 1996). Every Louisiana parish produces petroleum products and millions of barrels are transported across the state by barges, rail cars, pipelines and trucks (Louisiana Spill Science & Technology Bulletin, Vol. 8, Nos. 5–6, pp. 445–449, 2003 Ó 2003 Elsevier Ltd. All rights reserved Printed in Great Britain 1353-2561/$ - see front matter doi:10.1016/S1353-2561(02)00120-2 445 *Corresponding author. Tel.: +1-225-578-8810; fax: +1-225-578- 6423. E-mail addresses: clinda1@lsu.edu (C.W. Lindau), rdelaun@lsu. edu (R.D. Delaune), idevai@lsu.edu (I. Devai).