Distribution of essential heavy metals in the aquatic ecosystem of Lake Manzala, Egypt

Abstract

Lake Manzala is the largest and most productive lake of Egypt's northern coastal lakes and has socio-economic impacts. Pollution by heavy metals is the most significant type of pollution worldwide, particularly in Lake Manzala, which receives mixed discharges from densely populated areas. Water samples were collected at twelve sites around the lake in winter and summer of 2015. Samples of Eichhornia crassipes were collected in the winter, and Oreochromis niloticus samples were collected at two sites (8 and 10). V, Cr, Mn, Fe, Co, Ni, Cu, and Zn were analysed in these samples using inductively coupled plasma-mass spectrometry. The average metal concentrations were below the internationally accepted upper permissible limits and are improved compared to those in previous studies. However, the metal concentrations at the eastern and southeastern sites were higher than the allowable limits due to multiple waste discharges. Pollution assessment using pollution risk indicators indicated low to moderate concentrations of metal enrichment in the sediment and biota of the lake, except at sites near the eastern and southeastern drains; these latter sites were considered to be hazardous and should be taken into account in the current development efforts of the lake. Complete removal of floating plants transported by drains is recommended .

Heavy metal pollution in Manzala Lake sediments, Egypt: sources, variability, and assessment

“…Meanwhile, Cd had the lowest concentration values. The distribution pattern of Fe was mostly assigned to the influence of agricultural activities and domestic wastes discharged into the lake (Elmorsi et al, 2019 ). The results in Table 1 show the mean levels of HMs in the investigated area.…”

Effects of Heavy Metals in Lake Water and Sediments on Bottom Invertebrates Inhabiting the Brackish Coastal Lake Łebsko on the Southern Baltic Coast

“…Some others are treated as highly toxic, e.g., aluminium, which should not exceed the upper permissible limits in aquatic ecosystems; otherwise, they are treated as harmful. The limits differ depending on water type and application, country and the synergistic negative effects of pollution on living organisms [ 5 ]. Increased concentrations of heavy metals in water may lead to their toxic influence on fauna and flora in the pelagic zone.…”

Correlation between Polyaromatic Hydrocarbons (PAHs) Discharges at El-Manzala Wetland with the Relative Gene Expression of CYP19 Gene of the Nile Tilapia (Oreochromis. niloticus)

“…Disturbance of vitellogenesis is often related to injury to liver tissue (Muliari et al, 2019). The effects of pollutants on fish reproduction have been studied by numerous researchers who confirmed adverse effects on fish organs and mainly their reproductive abilities (Elmorsi et al, 2019).…”

“…El-Manzala Lake is one of the most dynamic aquasystems that were revealed to many threats over the last six decades due to agricultural drainage, municipal and industrial wastewater affecting Lake Biodiversity greatly (Elmorsi et al, 2019). The average fish production of El-Manzala Lake is 60,000 tons annually, where tilapia signifies more than 65% of fish species in the Lake (Abd El Tawab et al, 2020).…”