Multi-analytical screening of pesticides, phenols, heavy metals, and hydrocarbons in sediments from industrialized sites: a preliminary forensic interpretation

Abstract

A multi-analytical environmental forensic screening of pesticides, phenols, heavy metals, and hydrocarbons is performed on four representative sediment samples (S1–S4), selected from an initial set of 18 samples and collected at El Harrach, Mohammadia, Bordj El Kiffan, and Oued Smar in the Algiers area between February and July 2025, to establish a first-level contamination fingerprint supporting future source-discrimination studies. Thin-layer chromatography (TLC) and gas chromatography–mass spectrometry (GC–MS) are used for pesticide screening, Fourier-transform infrared spectroscopy (FTIR) is used for phenol screening, atomic absorption spectroscopy (AAS) is used for heavy metal determination, and automatic thermal desorption gas chromatography–mass spectrometry (ATD–GC–MS) is used for hydrocarbon analysis. The targeted organochlorine pesticides (OCPs) and organophosphorus pesticides (OPPs) are not detected under the applied screening conditions, and no FTIR-identifiable phenolic signatures are observed. Compound-specific GC–MS limit of detection (LOD) values range from 0.012 to 0.029 mg kg⁻¹ and limit of quantification (LOQ) values range from 0.036 to 0.088 mg kg⁻¹. Trace-level phenolic occurrence cannot be excluded by the FTIR screening approach. In contrast, all samples contain measurable concentrations of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), nickel (Ni), and zinc (Zn), with spatial variability. geoaccumulation index (I_geo) values indicate moderate to heavy contamination for selected metals, while sediment quality guideline (SQG) comparison reveals exceedances of the probable effect level (PEL) for Pb, Ni, and Zn. The pollution load index (PLI) exceeds unity at all sites. Hydrocarbon screening reveals recurrent aliphatic compounds in all samples, consistent with petroleum-derived or urban-industrial inputs. The combined metal–hydrocarbon profiles provide site-specific contamination fingerprints that differentiate between sampling locations and constitute a baseline dataset for future targeted source apportionment, ecological risk assessment, and sediment quality monitoring at the investigated industrialized sites in the Algiers area.