Prevalence and risk assessment of microplastics in the Nile Delta estuaries: "The Plastic Nile" revisited.

Recent research is directed toward studying plastic pollution in rivers, and estuaries due to the importance of freshwater bodies in all aspects of life. The river deltas and estuaries are interesting for studying the flux of plastics into the oceans. The Nile River has been identified as a hot spot of plastic litter flux in the eastern Mediterranean basin. In addition, it was nicknamed "Plastic Nile", yet this major river is largely unexplored with a lack of field measurements and adequate surveys. The current study was based on bridging this scientific gap. Three trips were conducted, covering 30 km in the Rosetta branch and 23 km in the Damietta branch, during the high water level in summer 2021, and 10 km off the inlet of Lake Burullus, in spring 2021. Microplastics in surface water ranged from 761 ± 319 to 1718 ± 1008 MPs/m3, and from 167 ± 137 to 1630 ± 1303 MPs/kg of dry sediments. Land use/ land cover mapping using Sentinel-2 images showed several sources of pollution that contribute to plastic contamination in the study area. Thermal analysis indicated seven plastic polymers; including, PE, PP, PET, PEVA, and PTFE, using discarded plastic products as reference materials. Microplastics were composed of colored and glossy fragments of sizes <500 µm, originating from land-based sources. Pollution load, polymer risk assessment, and ecological risk indices were calculated. Based on field observations macro-plastics were retained within the extensive network of infrastructure and dam systems. 80-106 billion MPs/year were estimated to flux from the Nile estuaries into the Mediterranean Sea. The current situation urges the development of binding plans to reduce plastic waste in the Nile Delta, as well as setting environmental monitoring points along the Deltaic coast.

Land use/cover and eco-toxicity indices for identifying metal contamination in sediments of drains, Manzala Lake, Egypt.

Six heavy metals in three main drains along the East Nile Delta were estimated to assess the environmental risk and employ land use/cover map of each drain. Composite sediment samples (n = 3) were collected from each drain. The elements were analyzed by Atomic Absorption Spectrophotometer. The order of metal ions in the sediments of three drains of Manzala lake take the following order: Fe > Co > Ni > Cr > Cd > Pb in El-Serw drain, Fe > Ni > Co > Cd > Cr > Pb in Hadous drain and Fe > Cd > Ni > Co > Pb > Cr in Bahr El-Baqar drain. Studied Pollution indices indicate that drains discharged into Manzala Lake are mostly contaminated by metals. Geo-accumulation index showed contamination by Cd in all sites especially in site 13 of Bahr El-Baqar drain and low values to others. The mean probable effect level quotient showed percent of 21% in Hadous and El-Serw drains and 73% probability of being toxic in Bahr El-Baqar drain. The mean effect range median quotient also showed 21% in Hadous and El-Serw to 49% probability of being toxic in Bahr El-Baqar drains. Index of anthropogenicity impact indicate that the man-made activity either agricultural, industrial or fisheries impacted in the appearance of metal ions in the following sequence; Cd > Co > Pb > Ni > Cr. Hazard severity according to hazard quotient and modified hazard quotient of Ni and Cd take the following sequence; El-Serw < Hadous < Bahr El-Baqar drains. For Cr is; Hadous < Bahr El-Baqar < El-Serw and Pb is; Hadous < Elserw < Bahr El-Baqar drains. According to contamination severity index showed low for Pb, Ni and Cr and severe for Co and Cd which take the sequence of; Bahr El-Baqar > El-Serw > Hadous.