Toxic phenolic compounds in the Egyptian coastal waters of Alexandria:spatial distribution,source identification,and ecological risk assessment

Abstract

ABSTRACT Poor published data are available for the detections of toxic phenolic compounds in the Egyptian Mediterranean Coast. Seasonal and spatial distributions of eight driven toxic phenolic compounds in coastal waters of Alexandria from ten different locations, situated between Abu Qir bay and Eastern Harbor during July, December (2018), and February, April (2019), were investigated to determine contamination status, possible sources, and ecological risks in the study area. For that purpose, a method was optimized for derivatization and detection of methylphenols, chlorophenols, and nitrophenols in water samples using GC-MS. This analytical method was validated using matrix spikes, indicating detection limits (0.02–0.5 µg/ml) and good recoveries (70–120%). Ranges of phenol concentrations in water samples were as follows: phenol (<LOD-109.2 ng/l), 2,4-DMP (<LOD-117.68 ng/l), 2-nitophenol (<LOD −87.09 ng/l), 2,4 dichlorophenol (19.93–66.30 ng/l), pentachlorophenol (13.50–60.08 ng/l), 2-chlorophenol (13.23–91.43 ng/l), 2,4,6-trichlorophenol (12.9–46.04 ng/l), and 4-chloro-3-methylphenol (15.2–52.3 ng/l). Methylphenols were the major group detected followed by nitrophenols and chlorophenols. Results of the risk assessment revealed that concentrations of the studied phenols were within the safe limits and lower than Surface Water Toxicity Reference Values (TRVs), giving no indication of pollution. Multivariate statistical analysis with different physicochemical parameters of water indicated the greatly variable behavior of phenolic compounds, and the exact sources of these compounds are difficult to identify since no major point sources of pollution are known in the area of study.