Controlling factors on the geochemistry of Al-Shuaiba and Al-Mejarma coastal lagoons, Red Sea, Saudi Arabia

Abstract

Geochemical and mineralogical analyses of bottom sediments collected from Al-Shuaiba (SHL) and Al-Mejarma (MJL) coastal lagoons, Red Sea were carried out. Mineralogically, the sediments consist mainly of carbonate minerals particularly aragonite, high and low Mg-calcite and traces of dolomite admixed with non-carbonate minerals including quartz, k-feldspars, plagioclase and traces of amphiboles, mica and clay minerals. The spatial distribution of major and trace elements at the bottom of the lagoons indicates two groups of elements. The first, less significant, is of terrigenous origin concentrates mainly in the shoreward direction. This group includes the silicates (Al2O3-Fe2O3-SiO2), Feldspars (K2O-Rb-Ba) and heavy minerals (V-Cr-Zr, TiO2-Y-Nb) related elements. The second most dominant group is the carbonate related elements (CaO-Sr) that concentrates in the seaward direction. The two lagoons are not affected by urbanization or anthropogenic impact, and hence the siliciclastic elements are related to the terrigenous influx mainly by aeolian transportation. The carbonate related elements are mainly of biogenic origin related to calcareous skeletal remains. The elemental distribution in the bottom sediments of the MJL is more homogeneous than those in the SHL reflecting the bottom conditions that are mainly controlled by lagoon morphology, hydrodynamic and the water circulation between the lagoon and the sea. Geochemical data show no obvious enrichment of Al-normalized redox-sensitive trace elements V and Cr suggesting that there is no variation in the bottom redox conditions in contrast with other previous studies. The information in this work is an important tool for biogeochemical and biological research projects in the Red Sea coastal lagoons.

Assessment of water contamination by potentially toxic elements in mangrove lagoons of the Red Sea, Saudi Arabia

“…The coastline of the Kingdom of Saudi Arabia is about 1,840 km in length, accounting for 79% of the eastern seaboard of the Red Sea (Badr et al, 2009 ; MEPA/IUCN, 1987 ). There are over twenty elongated and shallow lagoons extending along the Saudi the Red Sea coast (Basaham et al, 2019 ; Rasul, 2015a , 2015b ). In our study, we selected three lagoons, i.e., Jeddah, Yanbu, and Al-Shuaiba.…”

“…1 ). More details about this location are included in previous studies (e.g., Abohassan, 2013 ; Abu-Zied et al, 2011a , 2011b ; Basaham et al, 2019 ). Yanbu is an industrial city on the eastern coast of Red Sea.…”

Depositional Setting and Cementation Pattern of Al-Mejarma Beachrocks, Saudi Arabia: A Proxy for the Late Quaternary Red Sea Coastal Evolution

“…A low-lying intertidal flat borders the lagoon to the south, to the north and north-east, it is surrounded by coastal dunes, and to the east by beachrocks (Figure 1b). The recent bottom sediments of Al-Mejarma Lagoon are dominated by argillaceous sand and sandy mud; however, coarse bioclastic sediments are abundant along the inlet channel [69,70]. In an ongoing research, a short (2.5 m long) core collected from the intertidal flat shows stacking of two facies; lagoonal gray mud containing skeletal remains of bivalves, gastropods and corals, sharply overlain by intertidal flat yellowish-brown medium-grained sand.…”

“…Al-Mejarma Lagoon (Figure 1b) is a shallow back-barrier coastal lagoon covering an area of 0.88 km 2 with a maximum water depth of 6 m. It is located between latitudes N 20 • [69,70]. The water dynamic is variable, energetic along the channel, and very calm on both the northern and southern parts of the lagoon.…”

Major Factors Controlling the Elemental Composition of Al-Kharrar Lagoon Bottom Sediments, Rabigh, Saudi Arabia

“…Numerous coastal lagoons of different morphologies, surface areas, habitats, and depths extend along the Saudi Red Sea coast and connect to the Red Sea through single or multiple inlets [11]. The composition of their bottom sediments is largely dominated by autochthonous biogenic sediments with very rare lithogenous constituents of limited spatial distribution reflecting the extreme arid climate and the absence of perennial riverine input [12]. These lagoons are important fishing sites holding important living resources of commercial and ecological interest.…”