SALT MARSH RECOVERY FROM A CRUDE OIL SPILL: VEGETATION, OIL WEATHERING, AND RESPONSE
| Autor: | Gary Shigenaka, Charles B. Henry, Rebecca Z. Hoff |
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| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | International Oil Spill Conference Proceedings. 1993:307-311 |
| ISSN: | 2169-3358 2169-3366 |
| DOI: | 10.7901/2169-3358-1993-1-307 |
| Popis: | Responding to oil spills in marshes is always problematic, since inappropriate response activities can easily add to the overall damage to the marsh. When a spill of Prudhoe Bay crude oil covered a fringing Salicornia virginica marsh in Fidalgo Bay, Washington (northern Puget Sound) in February 1991, response personnel used several low-impact techniques to remove oil from the marsh, and minimized access by cleanup workers. Following the response, we established a monitoring program to track marsh recovery, and to document the effectiveness of the response techniques used and their impacts on the marsh. Through monthly sampling over a 16-month period, we monitored vegetative growth and tracked the chemical degradation of remaining oil. Sampling was conducted along transects located in four areas affected in different ways by the spill, including an oiled, trampled section; an oiled, vacuumed section; and an oiled, washed, and vacuumed section. In addition, a control transect was established in an unoiled adjacent marsh. The study included both biological and chemical components. Biological measurements included percent cover of live vegetation (sampled monthly) and below-ground plant biomass (sampled at the beginning of each growing season in April 1991 and April 1992). Sediment samples included surface sediment (monthly) and core samples collected at the beginning and end of the growing seasons. Sediment samples were analyzed using gas chromatography/mass spectroscopy, and indicator compounds were tracked to determine rates of oil degradation. Results from 16 months of post-spill monitoring show that foot trampling was most detrimental to marsh plants, while washing with vacuuming removed the most oil and minimized adverse impacts to vegetation. Dense clay substrate helped prevent oil from penetrating the sediment, thus minimizing acute toxic effects from oil exposure to marsh plant rootstock. By the second growing season post-spill, Salicornia and other marsh plants were growing in all areas except one heavily oiled patch. The monitoring program will be continued to determine if any delayed impacts occur in the marsh. |
| Databáze: | OpenAIRE |
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