Ramadan H. Abu-Zied

Effect of municipal wastewaters on bottom sediment geochemistry and benthic foraminifera of two Red Sea coastal inlets, Jeddah, Saudi Arabia

Al-Arbaeen and Al-Shabab inlets are two Red Sea coastal inlets lying on the mid-coast of Jeddah City, Saudi Arabia. Forty-four surface sediment samples were collected from these inlets and surrounding areas during June 2010. Water depths and the overlying environmental parameters (temperature, salinity, pH and dissolved oxygen) of these samples were measured. Sediment samples were analyzed for variables, such as loss on ignition (LOI, organic matter), CaCO3, heavy metals (Fe, Mn, Cu, Zn, Cd, Ni, Cr and Pb) and benthic foraminifera to assess any changes in the environment of the inlets and surrounding areas. Variables distribution patterns indicated that mud sediments dominated the inlets and enriched by LOI, heavy metals and Ammonia tepida–Quinqueloculina seminula assemblage, whereas coarse (sand–gravel) sediments dominated the substrates of surrounding areas and enriched by CaCO3 and Coscinospira hemprichii–Peneroplis planatus–Varidentella neostriatula assemblage with low values of LOI and heavy metals. Highest concentrations of Cu, Zn, Cd, Ni, Cr and Pb were recorded inside the inlets, especially near the discharge points, and they were positively correlated with the LOI and mud fraction indicating their affinity to anthropogenic materials. However, highest concentrations of Fe and Mn were typically recorded in the whole study area. These metals were positively correlated with the LOI values of the surrounding area, but in the inlets they were negatively correlated with the LOI, indicating an existence of reducing conditions caused by limited dissolved oxygen conditions at bottom waters of the inlets. Changing the environment within the inlets, according to higher concentrations of heavy metals and LOI, is probably responsible for the existence of the low density and diversity of benthic foraminifera and the absence of (reefal) symbiont-bearing species.

Ostracods and the Holocene palaeolimnology of Lake Qarun, with special reference to past human-environment interactions in the Faiyum (Egypt).

We present an ostracod record covering the past two millennia from an 8.25-m core taken from Lake Qarun, in the Faiyum Depression of Egypt. The occurrence of ostracod species in the lake is controlled primarily by variations in solute composition, which are in turn related to shifts in catchment land use. At times when the Faiyum Depression supported thriving agriculture, lake water contained Na+–Cl− brine, and Cyprideis torosa dominated the ostracod assemblage. When the Faiyum Depression experienced periods of environmental and economic decline, lake water contained Na+–HCO3− brine, and Limnocythere inopinata dominated. The relative abundance of other ostracod species provides additional information about past conditions in Lake Qarun including salinity and lake level changes. Overall, the ostracod assemblages provide evidence for human influences in the Faiyum, which extend back before instrumental or detailed observational records began.

Palaeoenvironment, palaeoclimate and sea-level changes in the Shuaiba Lagoon during the late Holocene (last 3.6 ka), eastern Red Sea coast, Saudi Arabia

Multi-proxy investigations of sediment lithology, geochemistry, benthic foraminifera, and δ18O and δ13C of Elphidium striatopunctatum were carried out on a sediment core SHUA3 (2.2 m long) spanning the last 3.6 ka and recovered from Shuaiba Lagoon, eastern Red Sea coast. Results showed that the interval before 1500 BC was deposited under supratidal to sabkha environments as indicated by the absence of benthic foraminifera and predominance of clastics enriched in terrestrial materials due to a relative lowering of sea level accompanied with arid conditions. From 1550 BC to the top of the core, the benthic species variations showed progressive depositional environmental changes from subtidal to intertidal conditions. Relative abundance of Sorites orbiculus co-varied with the reconstructed palaeo-tidal elevation, δ18O and δ13C values suggesting its sensitivity to climatic changes in the lagoon. δ18O and δ13C showed intervals of depletion at 350 BC, the beginning of the 1st millennium, AD 400 and AD 700 due likely to arid conditions that led to low evaporation and rapid water circulation. These are interleaved with intervals of enrichment at 150 BC, AD 200 and AD 600, due likely to warm conditions that led to high evaporation as testified also by changes in both palaeo-tidal elevation and Sorites orbiculus abundance. These proxies reached their highest and most prolonged levels during the AD 800–1550 interval, indicating warm conditions corresponding to the world ‘Medieval Warm Period’. Immediately after this period, the arid conditions of the ‘Little Ice Age’ prevailed throughout the AD 1550–1850 interval, and this was succeeded by the present warming conditions.

Factors influencing heavy metal concentrations in the bottom sediments of the Al-Kharrar Lagoon and Salman Bay, eastern Red Sea coast, Saudi Arabia

The Al-Kharrar Lagoon (KL) and Salman Bay (SB) are located on the eastern Red Sea coast, Saudi Arabia. The concentrations of heavy metals such as Fe, Mn, Zn, Cu, Ni, Pb, Co, and Cd in their bottom sediments were measured and correlated with the surface water temperature, salinity, pH and dissolved oxygen (DO), organic carbon (OC), carbonates, and sediment grain size. The highest concentration of metals in the KL is mostly attributed to influx of siliciclastics from wadies to the center and south-eastern parts of the lagoon where metals were directly correlated with salinity, pH, and mud. At the inlet stations, the metals were the lowest indicating that the KL acts as a buffer zone, preventing metals from dispersion into the Red Sea waters. But also, the enrichment factor (EF), there, for Mn, Zn, Cu, Co, and Ni, was the highest due likely to the effectiveness of biosorption by mucus algae that proliferate on coral debris and sand grains. The metals had no relationships with the OC, but with mud and Fe-Mn oxides due possibly to the presence of high DO. The brine waters of SB showed inverse relationships with the metals that ascribed probably to the occurrence of many soluble salts preventing precipitation of heavy metals into the sediments. Normalizing the heavy metals with Fe and the world average shale indicated that the bottom sediments of the KL and SB were uncontaminated and mainly influenced by natural sources.