OPTIMIZING HYDRAULIC CLEANING TECHNIQUES FOR OILED COARSE SEDIMENT BEACHES: MESOSCALE FIELD TRIALS

摘要

The objectives of this ongoing study are to: 1) determine the biological effects on intertidal biota associated with the use of hydraulic cleaning techniques, and 2) develop data on environmentally optimum combinations of hydraulic cleaning parameters for use by oil spill responders. This report presents the initial results of the Meso-scale Field Trials phase of the project. Hydraulic cleaning parameters examined in the Meso-scale Field Trials were: 1) water pressures from deluge to approximately 10.0 psi (69.0 kPa), 2) water temperatures from ambient to 60°C. In 1997, groups of colonized cobbles were collected from a donor beach in Lizzie Cove on Hunter Island, British Columbia, dosed with Bunker C fuel oil, and treated at various combinations of water pressure and temperature. Species monitored included the algae Fucus spp. And Mastocarpus papillatus; the barnacle Balanus glandula, limpets (Lottiidae) and snails Clittorina spp.). Un-treated oiled and unoiled controls were also established. The treated and control sets of cobbles were returned to the original donor beach and allowed to recover subject to natural environmental conditions, including predation and recruitment. Biological observations of abundance and mortality were made immediately post-treatment (48 to 72 hours) and one year post-treatment. These data were then statistically compared within treatment groups, between years and to control cobble data. Among the main findings of the Meso-scale Field Trials were: 1) greater mortality at all treatment levels one year post-treatment for Fucus spp., Balanus glandula, Lottiidae and Littorina spp. (with some exceptions), than seen immediately post-treatment. Trends in the data over increasing temperatures and pressures seen immediately post-treatment are not apparent one year post-treatment; 2) dramatic increases in the percent coverage of Mastocarpus papillatus were observed one year post-treatment as compared with pre-treatment coverage, including the unoiled control; 3) one year post-treatment, no significant differences were seen between mortalities in the various treatment combinations and the untreated, oiled control for Fucus spp. And Balanus glandula; and 4) preliminary evidence exists that pressure washing of oiled cobbles at high pressures and temperatures has negative effects on recruitment in Balanus glandula.