Occurrence, human health, and ecotoxicological risk assessment of pesticides in surface waters of the River Nile’s Rosetta Branch, Egypt

Abstract

In Egypt, the shortage of freshwater resources and their pollution constitutes a growing concern. Therefore, the objectives of this study were to (i) monitor the occurrence and spatiotemporal variations of 100 pesticides in surface water samples collected monthly (from July 2018 to June 2019) from El-Rahawy, Sabal, and Tala sampling sites along the Rosetta branch of the River Nile in Egypt, (ii) identify potential noncarcinogenic health risks for the local people through the lifetime consumption of contaminated drinking water, and (iii) perform an ecological risk assessment of aquatic organisms upon exposure to pesticides detected in surface waters based on the risk quotients (RQs) method. Of the 100 pesticides analyzed, 22 belonging to 11 chemical families were detected, and 75.5% of surface water samples were contaminated with one or more pesticide residues. The most frequently detected pesticide was malathion (57%), followed by chlorpyrifos (54%), atrazine (23%), and carbendazim (20%). Spatial distribution showed that the El-Rahawy site had the highest pesticide load (38.47 µg/L), and Sabal had the lowest (16.29 µg/L). Temporal variations revealed that the highest total pesticide concentrations were detected in summer (27.98 µg/L) compared to spring (23.16 µg/L), winter (19.18 µg/L), and autumn (11.85 µg/L). For non-carcinogenic risks of pesticides detected in surface water, the target hazard quotient (THQ) values were less than one. This implies that there is no potential human risk from exposure to drinking water at the sites under study. However, 13 pesticides presented high-risk quotients (RQ > 1), posing potential ecological risks to aquatic organisms.

Advanced Oxidation Processes Using Zinc Oxide Nanocatalyst for Detoxification of Some Highly Toxic Insecticides in an Aquatic System Combined With Improving Water Quality Parameters

“…The first one is the Renaissance Dam in Ethiopia which might cause a shortage in water supply and reduce Egypt's share of the Nile water by 14.5 billion cubic meters, which can irrigate three million Fadden (Chronicles, 2013). The second problem is environmental pollution in general, and particularly, agrochemical pollutants in surface water through the intensive use of pesticides and fertilizers (Derbalah and Ismail, 2013;Derbalah et al, 2014;Dahshan et al, 2016;Abbassy, 2018;Abdelrazek, 2019;Eissa et al, 2020;Eissa et al, 2021). The pollution of surface water and wastewater has increased sharply, and it constitutes a major problem due to the extensive use of these substances (Evgenidou et al, 2007).…”