Ecological Risk Assessment and Metal Pollution in Water and Fish in a Mediterranean Lagoon: A Case Study of Edku Lake, Egypt.

In the current study, laser-induced breakdown spectroscopy (LIBS) was utilized to assess the presence of heavy metals (HMs) in the water of Edku Lake and their accumulation in the muscles of edible fish, primarily Nile tilapia. The results obtained from LIBS were validated using the inductively coupled plasma (ICP) technique, specifically on iron (Fe) and aluminum (Al). The average concentrations of various metals, including Fe, Al, manganese (Mn), zinc (Zn), chromium (Cr), and cadmium (Cd) as determined by ICP, during winter and summer were found to be in the following ranges (in µg/l): Fe (266.67-474.44), Al (333.33-1184.44), Mn (7.11-8.23), Zn (9.00-8.66), Cr (5.00–23.23), and Cd (2.49-1.20, 1.26-0.52). For the fish muscle samples, the average metal content (in µg/g) was ranked in the following order: Al (9.43-5.57) > Fe (8.37-6.51) > Zn (0.9) > Mn (0.5-0.57) > Cr (0.08-0.1) > Cd (0.01-0.007). The obtained analytical results demonstrated good consistency between the LIBS and ICP methods. However, for the very low-concentration metals, such as Mn, Cr, and Cd in water, as well as all metals in fish, this level of agreement was not observed. The results of the present work revealed that Edku Lake faces challenges with poor water quality due to heavy metal pollution; however, the levels of metals in Nile tilapia remain within safe limits for human consumption. The LIBS technique is promising for monitoring heavy metals in water samples, but its sensitivity needs further improvement to effectively detect low concentrations of elements in biological tissues.