Anthropogenic-induced acceleration of elemental burial rates in blue carbon repositories of the Arabian Gulf

Since the discovery of oil in early 1900, the Arabian Gulf has experienced a continuous and fast coastal development leading to increase the human pressures on the marine environment and its enrichment with various pollutants. The present study attempts to describe the historical changes of trace elements in the sediments of vegetated coastal habitats in the western Arabian Gulf. 210Pb–dated sediment cores collected from seagrass, mangrove and saltmarsh habitats were analyzed to evaluate historical variations in concentrations and burial rates of 20 trace elements (Al, As, Ba, Ca, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, S, Sr, V and Zn). The highest correlations (Spearman correlation coefficients ≥0.51) were found between crustal elements (Al, Fe, Co, Cr, K, Na, Mg, Mn, Ni, V, and P), suggesting a common crustal source in the Gulf. The increased concentrations of these crustal elements in modern marine sediments of the Arabian Gulf seem to be linked to increased mineral dust deposition in the area. Over the last century, both elemental concentrations and burial rates increased by factors of 1–9 and 1–15, respectively, with a remarkably fast increase occurring in the past six decades (~1960 – early 2000). The considerable enrichment of trace elements in the Arabian Gulf during the last decades is most likely due to an increase in anthropogenic pressures, including industrial, urban and agricultural development. Our study demonstrates that sediments in vegetated coastal habitats provide long-term archives of trace elements concentrations and burial rates reflecting human activities in the Arabian Gulf.