Ecological Risk Assessment of Heavy Metals in Water, Sediment and Macrophytes of Two Drains in the Deltaic Mediterranean Coast of Egypt

Samples of water, sediment, and three aquatic plants, namely Phragmites australis, Typha domingensis, and Eichhornia crassipes, collected from ten stations were analyzed to estimate the pollution status with heavy metals in two drains (Kitchener and New Damietta) in the Nile Delta, Egypt. Ten indices were used to evaluate the ecological risk released by these metals. Results revealed high concentrations of Cu, Pb, and Cd in the Kitchener Drain water, while Fe was recorded in high concentrations in the New Damietta Drain water. Cu, Pb, Fe, and Cd were recorded to be within the Environmental Protection Agency (US-EPA) (2002) and World Health Organisation (2011) limits for water. A high concentration of Cu, Pb, and Fe was found in the New Damietta Drain sediment, while Cd was found in a high concentration in the Kitchener Drain sediment. Cu, Fe, and Cd were recorded to be within US-EPA (2002) limits for sediments, while Pb exceeded the permissible limits. Eichhornia crassipes accumulates higher concentrations of Cu, Pb, and Cd than the other plant species, while Phragmites australis exhibited the highest concentration of Fe. The study's plant species showed a decreased rate of metal translocation and distribution from their belowground tissues to their aboveground tissues, as indicated by the translocation factor values that were below one. As a result, the studied species accumulate heavy metals in their underground parts and do not effectively transfer metals from the belowground to the aerial parts. Thus, the examined species may be used to phytostabilize metal-polluted sediment as metal excluders.