Ecological Risk Assessment of Metal Pollution along Greater Cairo Sector of the River Nile, Egypt, Using Nile Tilapia, Oreochromis niloticus, as Bioindicator.

Wael A Omar,Wafai Z A Mikhail,Mamdouh M Poraas,Hanaa M Abdo,Tarek A Abou El Defan

doi:10.1155/2015/167319

Abstract

The present work aims to evaluate seasonal metal pollution along Greater Cairo sector of the River Nile, Egypt, using wild Nile tilapia, Oreochromis niloticus, as bioindicator and to conduct a risk assessment for human consumers. Greater Cairo is the largest populated area along the whole course of River Nile with a wide range of anthropogenic activities. Effects of metal pollution on fish body indices were studied using condition factor (CF) and scaled mass index (SMI). Metal pollution index (MPI) showed that the total metal load in fish organs followed the follwoing order: kidney > liver > gill > muscle which gives a better idea about the target organs for metal accumulation. Metal concentrations in fish muscle (edible tissue) showed the following arrangement: Fe > Zn > Cu > Mn > Pb > Cd. Metal's bioaccumulation factor (BAF) in fish muscle showed the following arrangement: Zn > Cu > Fe > Mn > Cd and Pb. The hazard index (HI) as an indicator of human health risks associated with fish consumption showed that adverse health effects are not expected to occur in most cases. However, the metals' cumulative risk effects gave an alarming sign specifically at high fish consumption rates.

Highlights

Greater Cairo is the largest metropolitan area in Egypt and Africa, the third largest urban area in the Islamic World after Jakarta and Karachi, and the world’s 16th largest metropolitan area with a total population of about 18 million according to the 2006 census [1]
The present study aims to provide comparable data on seasonality of metal abundance in water and tissues of wild O. niloticus collected from four sites covering the whole Greater Cairo sector of the River Nile and to evaluate possible ecotoxicological human health risks associated with fish consumption
The pattern of seasonal variation in values of condition factor of O. niloticus coincides with that reported by Hirpo [33] for the same species in Lake Babogaya, Ethiopia, where he attributed this variation to seasonal fluctuations in environmental factors, food supply and quality, feeding rate, stressors, and reproductive activity

Summary

Introduction

Greater Cairo is the largest metropolitan area in Egypt and Africa, the third largest urban area in the Islamic World after Jakarta and Karachi, and the world’s 16th largest metropolitan area with a total population of about 18 million according to the 2006 census [1]. The uprising increase in modern industries and agricultural, touristic, and urbanization activities in this area may be considered as the main sources of pollution to both the aquatic environment and its coexisting ecosystems. Loss of biodiversity, and habitat destruction are probably the main environmental threats for aquatic ecosystems. The excessive contamination of aquatic ecosystems has evoked major environmental and health concerns worldwide [2, 3]. Among the various toxic pollutants, trace metals represent a harmful group of elements due to their strong impact on stability of aquatic ecosystems, toxicity persistence, and accumulation tendency [7]. Some are potentially toxic (As, Cd, Pb, and Hg), others are probably essential (Ni, V, and Co), and many are essential (Cu, Zn, Fe, and Mn) [8]. Even essential metals can produce toxic effects when the metal intake is excessively elevated [9]

Methods

Results

Conclusion