Spatial distribution, structural characterization and weathering of tarmats along the west coast of Qatar

S Veerasingam,Jassim A Al-Khayat,K.P Haseeba,V.M Aboobacker,Shafeeq Hamza,P Vethamony

doi:10.1016/j.marpolbul.2020.111486

Abstract

Oil pollution resulting from natural and anthropogenic activities in the Arabian Gulf as well as oil residue in the form of tarmat (TM) deposited on the coast is a major environmental concern. The spatial distribution, chemical composition and weathering pattern of tarmat along the west coast of Qatar has been assessed based on the TM samples collected from 12 coastal regions. The range of TM distribution is 0–104 g m−1 with an average value of 9.25 g m−1. Though the current TM level is thirty-fold lesser than that was found during 1993–1997 (average 290 g m−1), the distribution pattern is similar. The results of ATR-FTIR spectroscopy indicate that aromatic compounds are higher in the north (N) coast TMs than those found in the northwest (NW) and southwest (SW) coasts, and Carbonyl Index values indicate that TM of NW coast is highly weathered compared to those found in the N and SW coasts.

Highlights

Tarmat (TM) or oil residue is originated from natural and anthropogenic marine oil spills, and deposited as mats of different sizes and forms on the inter-tidal or coastal belt after going through various weathering processes
The field campaigns clearly showed that the TM along the west coast of Qatar exhibit in several physical forms, wide range of sizes and with different degrees of weathering
The residual flow in the Arabian Gulf could be attributed to two principal factors: (i) a net anticlockwise circulation generated by wind forcing coupled with Coriolis effects and (ii) effect of horizontal density gradients, generated and sustained by evaporative losses and radiative heat transfer, and to a lesser extent by freshwater inflow at the head of the Gulf (Lardner et al, 1988)

Summary

Introduction

Tarmat (TM) or oil residue is originated from natural and anthropogenic marine oil spills, and deposited as mats of different sizes and forms on the inter-tidal or coastal belt after going through various weathering processes. During the 1991 Gulf War, about 10.8 million barrels of crude oil was spilled (world's largest oil spill) along with a large amount of ash fall-out (Soliman et al, 2019). The oil residues from NW coast of Qatar subject to GC–MS and CHEMSIC source identification methods revealed that the residues were originated from two different sources, viz., Saudi Arabia and Kuwait crude oils (Al-Kaabi et al, 2017). Researchers have documented oil spill contaminants at various beaches located along the western and eastern coasts of Qatar (Dahab and AlMadfa, 1993; Al-Madfa et al, 1999; Al-Kaabi et al, 2017; Rushdi et al, 2017; Soliman et al, 2019; Arekhi et al, 2020). In addition to previous oil spills, Qatar coast is continuously exposed to fresh oil spills, may not be in large quantities

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