Sediment Dynamics and Mercury Dispersal in Kuwait bay
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abstract
The purpose of this proposal is to investigate the seabed dynamics of Kuwait Bay in an effort to understand the fate and transport of mercury (Hg) and other particle-bound and porewater contaminants within the bay. Kuwait Bay contains extensive Hg contamination, primarily derived from a former Salt and Chlorine Plant (1965-1985) that dumped a minimum of 20 tons of Hg into Kuwait Bay. Hg is a highly insoluble, particle-reactive contaminant that preferentially attaches to fine-grained sediments (i.e. silts and clays), is easily measured, and provides an excellent conservative environmental tracer. Although previous research has investigated the extent of Hg contamination in Kuwait Bay, in many of their cores, the maximum depth of Hg was not reached, consequently, the delineation was incomplete. Seabed dynamics refers to the collective physical and biological processes that control sediment deposition, erosion, and seabed mixing. Quantifying the record of seabed dynamics can be accomplished through the use of short-lived radio-isotope geochronology of sediment cores, normally with 210Pb geochronology, coupled with grain size analyses and x-radiography. 210Pb has a half-life of 22.3 years, is part of the 238U series, emits both gamma and alpha particles and its activity can be measured using either gamma or alpha spectroscopy. X-radiography of slabs of intact sediment cores are collected to document the type of mixing and also to identify specific stratigraphic features of the cores. For this research, I propose to collect a grid of ultra-high-resolution seismic lines across Kuwait Bay. This will provide a regional context to the cores collected and also allow for the delineation of the extent of sub-environments. The seismic data will be used to select the locations of a series of at least 25 submersible vibra cores, push cores, and box cores across and along Kuwait Bay. The cores will be used to quantify seabed dynamics and the extent of Hg contamination across Kuwait Bay. The associated data will be used to develop both a conceptual model for seabed dynamics for Kuwait Bay, the quantification of the sediment accumulation and seabed mixing rates, and the residence time of sediments within the mixed layer. These results will be used to develop a processes-based assessment of the residence time for Hg and other particle-bound contaminants contained within the sediments of Kuwait Bay. This will provide a powerful tool for the management of the bay bottom sediments and future assessment of the fate and transport of other contaminants in Kuwait Bay.
