Oil exploration and production in the Arctic regions has resulted in spills of petroleum and salt water in tundra ecosystems. The transportation and use of refined petroleum in Arctic regions has also led to spills, and the cleanup and ecosystem restoration in these systems can often be complicated by the existence of ice-rich soil permafrost. Compaction, removal, or tearing of the protective vegetation and organic soil can result in thermokarsting and associated changes in plant communities, which may persist for decades. Such problems led the State of Alaska to establish recovery-based clean-up regulations for spills to tundra.A review was conducted of published literature, government agency spill files, and industry reports concerning spills of petroleum and saline water in tundra regions. A tundra spill database was created, which allows the determination of the spill frequency of refined petroleum, crude oil, and saline water. Refined-petroleum spills are more common and smaller than crude-oil and saline-water spills. Most spills are to wet tundra during winter, and winter spills are more effectively cleaned up than those in summer. In winter, snow contains most spills, frozen soil and frozen water bodies prevent much soil penetration, plants are dormant, and operation of heavy equipment is feasible on frozen ground. The use of fire to reduce the volume of petroleum spills in winter is not recommended. Heat from burning petroleum can melt snow, thaw soil, and allow the penetration of petroleum into soil.clean-up level) has been difficult to achieve without total removal of tundra vegetation and soil (Jorgenson and Carter 1996).Tundra is very sensitive to mechanical disturbance (Jorgenson and Carter 1991), especially where underlying permafrost is protected from melting by a surface organic layer. Compaction or removal of this organic layer over ice-rich soils results in thawing of the upper permafrost, Spills of crude oil and saline water have occurred to tundra r e s u , t i n g i n w e t > b o g g y ) t h e r m o k a r s t c o n d i t i o n s . E v e n due to oil exploration, production, and transportation in r e m o v a , o f t h e t o p few i n c h e s o f o r g a n i c s o i l c a n r e s u k in Alaska, Canada, and Russia. Spills of refined-petroleum thermokarst formation. This was shown at a crude-oil spill products have also occurred in tundra regions due to truck t h a t o c c u r r e d in 1989 near the Kuparuk River in Alaska, rollovers, mechanical failures, and leaks from fuel storage w h e r e t h e S t a t e o f A ) a s k a Department of Environmental tanks. To illustrate the size of tundra areas that are exposed Conservation (ADEC) required thatdiesel range organics to oil production, approximately 310,000 ha of land are (DRO) levels of500mg kg-1 be met within three years after within the area of the North Slope of Alaska that is the spill. The top 2-5 cm of organic soil were removed in currently under development for the production of oil and the winter following the spill. Some thermokarsting ...