Presentation
Evaluation of the Efficacy of Remediation Techniques at Hypersaline Salt Marsh Remediation Projects Impacted by the Gulf War Oil Spill
SessionSpill Impacts - Marshes
DescriptionThe Gulf War Oil Spill in 1991 was the largest marine oil spill in history, impacting approximately 800 km of shoreline in Saudi Arabia between the border with Kuwait and Abu Ali Island. In order to restore these sites, twenty-one remediation projects of varying size and complexity were conducted between 2009 and 2018 have been completed using different combinations of restoration techniques at intertidal sites. In October 2022, a synoptic survey was conducted to assess the efficacy of remediation techniques across the entire geographic scope of the remediation projects, as a complement to the long-term monitoring program, which measures progress of restoration at fixed sites. The survey measured abundance and distribution of common intertidal fauna and presence of oil and algal mat across the following remediation activities: excavation of extant and new channels; creation of marsh topographic heterogeneity (“mounds”); removal of asphalt pavement and heavily oiled sediments; and tilling. Relationships between field observations and GIS datasets summarizing elevation, drainage distance, and inundation were assessed to summarize the efficacy of remediation activities. Additional remediation activities were described for each site, based on quantitative and qualitative field data.
Results indicated that treated areas generally had reduced thick algal mat cover compared to untreated sites; however, vegetation recovery was occurring more slowly, and dependent on local conditions. Crab and gastropod abundance were relatively limited in area compared to the overall area of the projects, a fact that may be due to specific elevation and inundation requirements of these species but may also represent limited dispersal capability for some species. Channel excavation and mound construction were associated with increased abundance and cover of marsh vegetation relative to untreated sites, especially at low-moderate elevations. Mound creation facilitated the development of vegetation communities, compared to untreated sites without mounds. Tilled areas showed greater ecosystem recovery compared to untilled areas, and at tidal flat sites, tilled areas had higher gastropod and crab abundance relative to untilled areas. For plots in channelized/salt marsh settings, metrics for plots along refreshed channels are improved as compared with plots along newly excavated channels, even after accounting for differences in distance to MSL (or other physical or hydrologic factors). Most sites showed sufficient progress that recommendations for additional remediation efforts were limited relative to the original footprint of the project. Recommendations for additional remediation work primarily consisted of additional tilling in areas that lacked vegetation cover, had persistent algal mat cover or substantial oiling. Other activities recommended included additional AP/HOS removal, hydrological remediation, perennial planting, and rubbish removal.
Results indicated that treated areas generally had reduced thick algal mat cover compared to untreated sites; however, vegetation recovery was occurring more slowly, and dependent on local conditions. Crab and gastropod abundance were relatively limited in area compared to the overall area of the projects, a fact that may be due to specific elevation and inundation requirements of these species but may also represent limited dispersal capability for some species. Channel excavation and mound construction were associated with increased abundance and cover of marsh vegetation relative to untreated sites, especially at low-moderate elevations. Mound creation facilitated the development of vegetation communities, compared to untreated sites without mounds. Tilled areas showed greater ecosystem recovery compared to untilled areas, and at tidal flat sites, tilled areas had higher gastropod and crab abundance relative to untilled areas. For plots in channelized/salt marsh settings, metrics for plots along refreshed channels are improved as compared with plots along newly excavated channels, even after accounting for differences in distance to MSL (or other physical or hydrologic factors). Most sites showed sufficient progress that recommendations for additional remediation efforts were limited relative to the original footprint of the project. Recommendations for additional remediation work primarily consisted of additional tilling in areas that lacked vegetation cover, had persistent algal mat cover or substantial oiling. Other activities recommended included additional AP/HOS removal, hydrological remediation, perennial planting, and rubbish removal.
Authors
Vice President
Senior Scientist
Event Type
Paper
TimeWednesday, May 15th4:10pm - 4:30pm CDT
Location298-299
Remediation