PAHs and hopanes in the surface sediments of Qatar coast and their ecological risks: Comparison with regional and global coastal regions.

The distribution, characteristics, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) and hopanes in the surface sediments collected along the Qatar coast were investigated. Concentration of ∑14PAHs and hopanes ranged between 0.076 and 7.04 ng g-1 (mean: 2.60 ng g-1), 100 and 700 ng g-1 (mean: 205 ng g-1), respectively. Sediment samples were dominated by high molecular weight PAHs composition (4-6 rings). Diagnostic ratios of PAH concentrations showed both petrogenic and pyrogenic origins of PAHs, with a higher percentage of pyrogenic sources. The ecological risk levels of PAHs were estimated using sediment quality guidelines (SQG), mean probable effect level quotient values (PEL-Q), carcinogenic toxic equivalent quantity (TEQ), and risk quotient (RQ) evaluation methods. The calculated TEQ values (0.00012-0.85 ng g-1) were lesser than those in other locations around the globe, and were also within the safe level (600 ng g-1) suggested by the Canadian soil quality guidelines.

Characteristics and sources of anthropogenic and biogenic hydrocarbons in sediments from the coast of Qatar.

Surface sediment samples from the coastal zone of Qatar were collected and analyzed to determine the characteristics, and sources of anthropogenic and biogenic hydrocarbons. The main compounds in these surface sediments included n-alkanes, methyl n-alkanoates, diterpenoids, hopanes, steranes, phthalate esters, polycyclic aromatic hydrocarbons (PAHs) and unresolved complex mixture (UCM). Their total concentrations ranged from 18.7±3.7-81.1±7.5ng/g (3.7±0.6-10.4±4.8%) for n-alkanes, 8.3±2.3-51±3.4ng/g (3.0±2.0-5.6±2.0%) for methyl n-alkanoates, 1.8±0.1-10.5±1.0ng/g (1.0±0.5-0.4±0.1%) for diterpenoids, 0.0-79.3±7.4ng/g (0.0-7.9±0.6%) for hopanes, 0.0-32.9±7.9ng/g (0.0-6.5±1.0%) for steranes, 0.7±0.1-36.3±3.4ng/g (0.1±0.1-1.9±3.4%) for phthalates, 0.30±0.2-7.8±0.7ng/g (0.02±0.04-0.42±0.72%) for PAHs, and 38±9-609±57ng/g (38.5±13.4-56.5±13.4%) for UCM. The major sources of these lipids were anthropogenic petroleum residues and plasticizers (80-89%), with lesser amounts from natural higher plants and microbial residues (11-20%). Petroleum residues and plasticizer inputs to the coastal sediments of Qatar likely affect the marine ecosystems and associated species groups as well as shallow coastal nursery and spawning areas.