Studying and understanding the complexity and interactions of different factors influencing stream sediment quality is necessary for the development of successful water quality management strategies. This study aims to evaluate the level of contamination by potentially toxic elements (PTEs) (As, Co, Cr, Cu, Mn, Ni, Pb, V, Zn) of the stream sediments of the Nile River. During the spring of 2019, river sediments were sampled at 23 sites along the Nile River. For each sample, one aliquot was digested in aqua regia and analyzed by ICP-MS for pseudo-total concentration, while for another aliquot, sequential extraction procedures were applied to determine chemical speciation. Compositional data analysis (CoDa) and k-means were applied to recognize the contribution of natural and anthropogenic sources, while pollution indices (EF, RAC) and sediment quality guidelines (SQGs) were applied to assess the ecological risk to biotic species. The results reveal that elements such as Cr, Mn, V and Fe, found in high concentrations in almost all samples (Cr up to 739 mg/kg, Mn up to 1942 mg/kg, V up to 507 mg/kg, Fe up to 98,519 mg/kg), have a natural origin, while the concentrations of Cu (up to 69 mg/kg), Ni (up to 88 mg/kg), Co (up to 42 mg/kg) and As (up to 9.8 mg/kg) are linked to both natural and anthropogenic processes. Sequential extraction shows that Mn, Co, Ni and, in some sites, Cu and Zn, are the most bioavailable elements. These elements present a high risk of toxicity, while the remaining elements imply a low-to-moderate risk.

Heavy metals such as cadmium (Cd) pollute the environment. Heavy metal pollution endangers the Nile River since it serves as an irrigation and freshwater source for the cities and farms that line its banks. Water and sediment samples from the Nile River were tested for Cd content. In addition, a sequential experiment analytical method was performed to determine the metal’s relative mobility. According to the data, there is an average of 0.16 mg kg⁻¹ of Cd in sediments. The BeniSuef water treatment plant and brick factory, the iron and steel factory of Helwan, the oil and detergent factory of Sohag, and the discharge of the cement factory in Samalut had the greatest concentration of Cd in their vicinity. According to the risk assessment code, there are four categories of Cd: residual (57.91%), acid-soluble (27.11%), reducible (11.84%), and oxidizable (3.14%). Bioavailable and mobile Cd levels in sediment and water were found in Beni Suef, Aswan; Helwan; Samalut; Sohag; and Helwan. Because the other metal is highly bioavailable, its concentration is not a risk factor at the Samalut station. Cd’s toxicity and bioaccumulation make it an extra hazard to aquatic animals and human life. There should be a deterministic approach to monitoring Cd near industrial sources.

Edku lagoon is one of the important aquaculture sectors in the Nile Delta of Egypt. Recently, the lagoon has become a sink of discharge wastewater from different anthropogenic sources. The present work aims to study physicochemical parameters, level of nutrients and heavy metal concentrations in water of the lagoon to assess the water quality and identify the potential pollution source(s). Water quality index (WQI), eutrophication index and multiple heavy metal pollution indices (HPI, HEI, PI and Cd) in addition to evaluation of human health risk (HQdermal) model were applied. The obtained data revealed that physicochemical parameter varied between 7.62 - 8.90 for pH, 1.2 – 12.2 g/l for salinity, 3.5 – 12.5 mg/l for dissolved oxygen, 1.3 – 1.9 mg/l for ammonia, 0.065 – 0.191 mg/l for nitrite, 0.217 – 0.915 mg/l nitrate, 0.198 – 0.527 mg/l for orthophosphate, and 51.32 – 102.7 μg/l for chlorophyll-a. The average concentrations of heavy metals were 0.439, 0.322, 0.290, 0.328, 0.059, 0.040, 0.00005 ppm for Fe, Mn, Zn, Cu, Pb, Cd and Hg, respectively. Based on WQI, the lagoon was classified as bad water, while EI result varied between eutrophic to mesotrophic. The pollution indices revealed to lagoon water is highly contaminated based on HPI, HEI and Cd and varied between slightly affected to seriously affected by heavy metals according to PI. Human health risk showed that, HQdermal for all metals except Cd lower than the unity.

Sedimentological and geochemical studies are integrated to determine the potential of heavy metals in the Middle Nile Delta soil. Four sources of trace elements were identified; a geogenic source includes Fe, Co, Cr, Ni and V, along with Ca that partly enhanced by anthropogenic input, and three dissimilar anthropogenic sources grouped the elements as follow; As, Pb, Zn Cu, Ba and P which derived mainly from industrial activities; Ba, Pb, Zn and Cu group is likely dispersed by traffic emissions, and P, As and Cu elements group which influenced by agrochemical application and drain water irrigation. The concentrations of studied elements increasing with decreasing the particle size. Moreover, two groups of mineral assemblages of soil are recognized; the first group deposited with one particle fraction and inherited from parent materials, The second one includes non-silicate minerals clasts, deposited with more than one fraction and most likely of anthropogenic source.