Occurrence and Distribution of Some Contaminants of Emerging Concern in the Sediments from Imo River Nigeria: A Non-Targeted Analysis Approach

Abstract

This is a non–targeted assessment of the occurrence and distribution of contaminants of emerging concern in sediment samples of the Imo River, Nigeria. Three (3) sampling locations—Ekenobizi (Imo State), Owerrinta (Abia State), and Oyigbo (Rivers State) — along the Imo River were selected for the study based on their high human population and numerous anthropogenic activities. Sediment samples (9) were collected from upstream, midstream, and downstream of each of the sampled locations using the grab sampling method and taken to the laboratory for analysis within three hours after sampling.  A non-targeted screening for Contaminants of Emerging Concerns (CECs) was done using gas chromatography – mass spectrometry (GC-MS) after preparation of the samples. The results showed contamination of the river with eighty-four (84) unique CECs distributed as follows: 21 CECs at Ekenobizi axis, 32 CECs at Owerrinta axis and 34 CECs at Oyigbo axis across the upper stream (US), midstream (MS) and downstream (DS) points. Some of the CECs were location-specific, while some were detected across the three sampling points of each location. Three of the detected CECs were common to both the Owerrinta and Oyigbo axes. Among the detected compounds were siloxanes, fatty acids, amines, hydrocarbons, and other organic chemicals. These chemicals are traceable to pharmaceutical and personal care products, agro-chemicals, and other industrial chemicals, and they exhibit varying degrees of ecological risks. There was no significant difference among the CECs concentrations of the sampled locations (where p > 0.05, p = 0.909).  The detection and concentration CECs in the study area indicate a critical trend of environmental contamination and potential ecological risks, consistent with global studies.