Sources of hydrocarbons and their risk assessment in seawater and sediment samples collected from the Nile Delta coast of the Mediterranean Sea

Mohamed A Hassaan; Safaa Ragab; Amany El Sikaily; Ahmed El Nemr

doi:10.1038/s41598-024-55339-4

Sources of hydrocarbons and their risk assessment in seawater and sediment samples collected from the Nile Delta coast of the Mediterranean Sea

Sci Rep. 2024 Mar 1;14(1):5082. doi: 10.1038/s41598-024-55339-4.

Authors

Mohamed A Hassaan¹, Safaa Ragab¹, Amany El Sikaily¹, Ahmed El Nemr²

Affiliations

¹ Environment Division, National Institute of Oceanography and Fisheries (NIOF), Kayet Bey, P.O. 21556, Elanfoushy, Alexandria, Egypt.
² Environment Division, National Institute of Oceanography and Fisheries (NIOF), Kayet Bey, P.O. 21556, Elanfoushy, Alexandria, Egypt. ahmedmoustafaelnemr@yahoo.com.

Abstract

The aim of this work is to examine the levels, distribution, bases, and hazards of n-alkanes (n-C9 to n-C20) and PAHs in the seawater and sediments around oil production locations in the whole delta region. The variations in the levels of PAHs and n-alkanes in seawater and sediment of the Nile delta coast of the Mediterranean were investigated using GC-MS/MS. The Σn-alkanes residues ranged between 12.05 and 93.51 mg/L (mean: 50.45 ± 17.49 mg/L) and 4.70 to 84.03 µg/g (mean: 31.02 ± 27.995 µg/g) in seawater and sediments, respectively. Total PAHs concentrations ranged between 4.485 and 16.337 μg/L (average: 9.47 ± 3.69 μg/L) and 1.32 to 28.38 ng/g (average 8.61 ± 7.57 ng/g) in seawater and sediment samples, respectively. The CPI (carbon preference index) values fluctuated between 0.62 and 1.72 (seawater) and from 0.234 to 2.175 (sediment), proposing the variation sources of n-alkane in the studied area. PAHs concentrations were lower than the Effective Range Low (ERL) and Effective Range Median (ERM) levels. The Toxic Equivalent Quotient (TEQ) values oscillated between 0.002 and 6.84 ng/L and from 3.72 to 13.48 ng/g for the seawater and sediment samples, respectively. The Ant/(Ant + Phe) ratio in sediment and seawater samples indicated a pyrolytic source while the BaA/(BaA + Chry) ratio indicates petrogenic sources in most of the studied stations.

Keywords: n-alkanes; Mediterranean; PAHs; Pollutants source identification; Risk assessment; Seawater and sediment.