Assessment of Organic and Inorganic Pollutants Along The Qatari Coast

Abstract

Qatar sits in the middle of the world's most important hydrocarbon producing areas where significant regional refining activity and shipping traffic take place. In addition to significant local coastline, development prominently along the eastern coast, has taken place over recent decades. Protecting Qatar's marine ecosystems from the adverse effects of environmental contaminants is a core component of the Environmental Development pillar within the National Vision 2030. However, a limited number of studies have investigated contaminant concentrations in the coastal environment of Qatar. The accumulation of contaminants in aquatic environments can affect coastal and marine ecosystems, and cause adverse effect on marine organisms and human health. This study aims to determine contamination in Qatar's coastal environment by measuring organic and inorganic contaminants, along with physiochemical parameters, at four sites located on the contrasting east and west coast of the country. The Pearl Oyster Pinctada radiata, which is considered an iconic organism in Qatar, was used to determine a baseline of contaminants in an aquatic organism. Surface seawater, surface sediment and oysters were collected four times over two years in different seasons from the four sites. In-situ parameters (temperature, pH, and salinity), and abiotic parameters (TOC and grain sizes) were measured for seawater and sediment. Organic (TPHs, PAHs) and inorganic contaminants (trace metals including: Cd, Cu, Cr, Ni, Pb and Zn, T-Hg) were measured in all samples. Overall, Al Wakra (higher in boat traffic and fueling activities) on the east coast reported the highest levels of contaminants. High PAHs were observed in oyster tissues, while high Pb was noted in seawater and high Zn was observed in sediment and oyster. Benzo (a) pyrene was the highest compound detected in oyster. However, high TPHs were also noted in oyster tissues from Simaisma. At Al Khor, also on the east coast, high level of TPHs were recorded in seawater, while high PAHs and TOC observed in surface sediment, which had a relatively higher clay and silt content than other sites. Umm Bab (with a desalination plant near the coast), the sole sample site on the west coast, showed the highest level of TOC in seawater and sediment, highest Ni in seawater and highest total mercury in oyster . Our results, in general, report lower levels in seawater and sediment compared to other studies in the region and more widely; however, in oysters most of the contaminants are higher when compared to international guideline values. These higher levels indicate the potential for these filter-feeding organisms to absorb contaminants into their tissues from the environment that surrounds them. Additionally, bioaccumulation can occur. This study provides background information for further investigation to understand the presence and distribution of organic and inorganic contaminants in Qatar's rapidly changing coastal environment. It indicates the usefulness of applying a holistic view to environmental monitoring including the use of biomonitoring.