NET ENVIRONMENTAL BENEFIT ANALYSIS (NEBA)OF DISPERSED OIL ON NEARSHORE TROPICALECOSYSTEMS DERIVED FROM THE 20 YEAR“TROPICS” FIELD STUDY

摘要

In November 1984, non-treated Prudhoe Bay crude oil and dispersedrnPrudhoe Bay crude oil were intentionally released into twornseparate sites, representative of nearshore mangrove, seagrassrnand coral ecosystems, as part of the Tropical Oil Pollution Investigationsrnin Coastal Systems (TROPICS) field study in Bahia dernAlmirante, Panama. Data on the relative effects of non-treatedrncrude oil and dispersed crude oil on these ecosystems (comparedrnto a reference site) were acquired and analyzed over various periodsrn(30 days, 3 months, and 2.6, 10, 17, 18, and 20 years).rnIn the short term, the oil caused mortality to invertebraternfauna, seagrass beds, and corals at both sites. At the non-treatedrncrude oil site, there was also significant mortality to the mangrovernforest. Twenty-year observations and mangrove substrate corernsamples reveal the continued presence of oil and diminished mangrovernrepopulation, as well as substrate erosion, at the non-treatedrncrude oil site. No oil was detected and no long-term impacts werernobserved at the dispersed crude oil and reference sites. These resultsrnprovide baseline scientific data for developing a Net EnvironmentalrnBenefit Analysis (NEBA) of dispersant use in nearshorerntropical systems.rnThis paper is a review of TROPICS data and its application tornNEBA preparation. Data and NEBA from the 20-year TROPICSrnstudy clearly show that the use of dispersant in the nearshore environmentrnis a sound strategy for both minimizing environmentalrndamage to tropical ecosystems and for providing the best opportunityrnfor recovery and repopulation in this environment. Results ofrnthis work should be applicable to similar tropical ecosystems.