Selection of Nutrients to Enhance Biodegradation for the Remediation of Oil Spilled on Beaches1

Abstract

ABSTRACT Laboratory studies were conducted to determine the fate of fertilizers proposed for application to the Alaska shoreline in support of the Alaskan Oil Spill EPA Bioremediation Project. Fertilizer application is thought to provide indigenous organisms with nutrients that appear to be limited on ocean beaches. The experiments were developed strictly to test the durability, release rates, and application procedures of a variety of fertilizer types. The effects of tidal movement on a beach were simulated by two separate conditions, static and dynamic. The static condition represented periods when the beach material was under water and turbulence was at a minimum. This condition was simulated in the laboratory by submerging the nutrient in a beaker of simulated seawater (with or without beach material, depending on the nutrients being tested). These experiments ran continuously over a three-month period, with water exchanges according to a planned schedule. Nutrient concentrations were measured in the exchanged water. Dynamic conditions represented the forces on beach material as the water moved from low to high tide and back to low tide. In the laboratory, the condition was simulated by applying the nutrients to beach material piled in one end of a long, narrow tray placed on a rocker table. When the rocker table was operating and enough seawater had been added to cover the beach material (in the rocker table's low position), a gentle sloshing of the water over the materials resulted. These experiments generally lasted one to two hours, during which time liquid samples were collected for nutrient analyses. Durability of the fertilizers was measured by visual observation and freeze/thaw determinations. The experimental setup was economical and performed well. The fertilizer most suited for field trial was found to be isobutyraldehyde diurea briquettes, which produced a slow, continuous release of nutrients.