Geochemical characterization and source identification of tarmat deposits along the coast of Qatar (Arabian/Persian Gulf)

Tarmat deposits along the Qatar coastline were investigated using trace-metal concentrations and diagnostic ratios (Co/Ni, V/Ni, Co/V, V/Cu, and Fe/Ni) to assess weathering effects, spatial variability, and potential sources. The samples were collected between September and November 2019 from 13 different locations along the west, north, and northeastern coasts of the Qatar Peninsula. Trace-metal concentrations were on average significantly higher in island samples (V 1284 µg/g; Ni 492 µg/g; Co 6.48 µg/g) compared with mainland sites (V 305 µg/g; Ni 108 µg/g; Co 1.66 µg/g; p < 0.05). Multivariate statistical analyses (PCA and HCA) revealed systematic patterns linking metal composition with spatial distribution and weathering categories. Regression analysis of metal-to-aluminum (Me/Al) ratios against marine suspended particulate matter and aeolian dust showed strong correlations (R² = 0.83–0.89; p < 0.01), suggesting potential combined atmospheric and marine influences on trace metal signatures. The composition of the tarmats is influenced by environmental factors as well as their degradation and weathering. Diagnostic metal ratios were consistent with crude oil signatures reported from the northern and northwestern Arabian/Persian Gulf, indicating predominantly regional inputs rather than long-range transport. Overall, the study demonstrates that trace-metal ratios, supported by multivariate analysis, provide a useful framework for tarmat characterization and environmental assessment and support other scientific investigations on tarmats in the Gulf region.