The role of transport processes of particulate mercury in modifying marine anthropogenic secondary sources, the case of Haifa bay, Israel

Abstract

We have assessed the redistribution of a secondary source of sedimentary anthropogenic mercury in the Haifa bay (HB) area (SE Levantine basin), which is the northern sink for Nile-driven sand. A long-term (30years) ~80% decrease of the total sedimentary mercury concentrations (THg) was recorded in the inner bay, while an up to 3-fold increase was recorded in the top sediments of the outer bay. Sedimentary THg depth profiles and their temporal variability were used to model the main re-distribution processes, mainly resuspension associated with winter storm-derived transport. This mechanism transforms a secondary, sandy and well-aerated sink into a tertiary, more silty and hypoxic source at adjacent peripheral areas, affecting mercury bioavailability. We revisited the concept of environmental relaxation, i.e. the rate of return of a polluted environment to an acceptable state, showing that sedimentary transport processes may affect the associated ecological risks, mainly at shallow-water coastal sites.