Assessment of artificial groundwater recharge potential through estimation of permeability values from infiltration and aquifer tests in unconsolidated alluvial formations in coastal areas.

Twenty infiltration tests and 12 pumping tests were carried out in Wadi Baysh in southwestern Saudi Arabia. The objective of the study was to assess the soil and aquifer permeability from the point of view of artificial groundwater recharge. Infiltration tests showed that the soil permeability values ranged from 0.58 to 37.15 m/day and showed good recharge potential. The analysis of the pumping tests showed that the aquifer permeability values ranged from 2.6 to 57.4 m/day and were approximately within the same range as those obtained from infiltration tests. Monitoring of groundwater levels in a few wells before and 1 month after a heavy rainfall event in August 2016 shows an average increase of 2.25 m in the groundwater levels which substantiates the recharge rates obtained from infiltration and pumping tests. Average annual groundwater recharge for the area calculated from water table fluctuation method is 72.08 mm/year indicating that the lower reaches of Wadi Baysh catchment has good potential for groundwater recharge and if managed properly can help in tackling the problem of groundwater depletion due to excessive pumping.

Application of water quality indices and health risk models in the arid coastal aquifer, Southern Saudi Arabia.

A systematic study was performed in the arid coastal aquifer to evaluate groundwater quality using drinking water quality indices (DWQI) and health risk assessment models in southern Saudi Arabia. Groundwater samples were collected (n = 80) and analysed for major and minor ions. Results suggest that 85% of wells are unsuitable for drinking due to high salinity and hardness. Likewise, high NO3- and F- are encountered in 51% and 46% of wells, respectively. High salinity, Cl- and SO42- are noticed in the coastal wells, which are derived from saline sources, evaporation and anthropogenic activities. High NO3- is originated from anthropogenic sources and the nitrification process. Recharge of wastewater with high NO3- is mixed with high salinity groundwater in this shallow aquifer. DWQI indicates that 66% of samples are poor to unsuitable classes. Wells with poor quality groundwater existed in the coastal belt and water quality is degraded while moving from upstream to downstream. The average values of hazard quotient (HQoral, NO3-, F-) and total hazard index (THI) ensured that highly vulnerable groups are in the order of infants > children > adults. In the study region, the THI are > 1 in 75% (adults), 89% (children) and 94% (infants) of samples, respectively. The spatial distribution of HQoral reveals that groundwater in the coastal and southern regions is not advisable for direct oral ingestion, which causes serious non-carcinogenic health risk to inhabitants. Groundwater in these regions needs proper treatment to remove the contaminants before use.

Contamination of the marine environment in Egypt and Saudi Arabia with personal protective equipment during COVID-19 pandemic: A short focus.

Plastic pollution and its impact on marine ecosystems are major concerns globally, and the situation was exacerbated after the outbreak of COVID-19. Clean-up campaigns took place during the summer season (June-August 2020) in two coastal cities in Egypt (Alexandria and Hurghada) and Jeddah, Saudi Arabia to document the abundance of beach debris through public involvement, and then remove it. A total of 3673, 255, and 848 items were collected from Alexandria, Hurghada, and Jeddah daily, respectively. Gloves and face masks (personal protective equipment "PPE") represent represented 40-60% of the total plastic items collected from each of the three cities, while plastic bags represented 7-20% of the total plastics litter collected from the same cities. The results indicated the presence of 2.79, 0.29, and 0.86 PPE item m-2 in Alexandria, Hurghada and Jeddah, respectively. This short focus provides an assessment of the environmental impacts of single-use gloves and masks used for COVID-19 protection from June to August 2020. To the best of our knowledge, this study presents the first such information from the Middle East, specifically Egypt and Saudi Arabia. It highlights the need for further knowledge and action, such as safe, sustainable, and transparent waste management processes related to COVID-19 to reduce the negative impacts now, as well as in future events. Furthermore, this study helps in achieving key components of the United Nation's Sustainable Development Goals (SDGs). This short focus can serve as a multipurpose document, not only for scientists of different disciplines but for social media and citizens in general.

Sustainable and resilient management scenarios for groundwater resources of the Red Sea coastal aquifers.

Gravity Recovery and Climate Experiment (GRACE) data, along with readily available remote sensing datasets and the outputs of land-surface and climate models, are used to monitor spatiotemporal variabilities in the groundwater resources of the Red Sea Coastal Aquifer (RSCA) system in Saudi Arabia; to investigate their responses to climate projections; and to provide sustainable and resilient management scenarios for these resources. Our results indicate that, during the investigated period (April 2002-June 2017), the RSCA received an average annual recharge of 3.16 ±â€¯0.52 km3. Recharge events (~16% of rainfall) are related to the observed increase in rainfall rates. Analysis of climate models' outputs over the RSCA indicates an increase in the median annual rainfall (17-31%) and recharge rates (2.7-4.9%) by the end of the 21st century. To ensure sustainable management and utilization of RSCA's water resources, groundwater extraction should be located in the southern and central parts of the aquifer, and groundwater extraction rates should be kept lower than 2.0 km3/yr. Findings highlight the importance of GRACE data as a unique, cost-effective, and decisive tool in monitoring the health of coastal and inland aquifer systems across the globe.

Toxicity of iron oxide nanoparticles to grass litter decomposition in a sandy soil.

We examined time-dependent effect of iron oxide nanoparticles (IONPs) at a rate of 2000 mg kg-1 soil on Cynodon dactylon litter (3 g kg-1) decomposition in an arid sandy soil. Overall, heterotrophic cultivable bacterial and fungal colonies, and microbial biomass carbon were significantly decreased in litter-amended soil by the application of nanoparticles after 90 and 180 days of incubation. Time dependent effect of nanoparticles was significant for microbial biomass in litter-amended soil where nanoparticles decreased this variable from 27% after 90 days to 49% after 180 days. IONPs decreased CO2 emission by 28 and 30% from litter-amended soil after 90 and 180 days, respectively. These observations indicated that time-dependent effect was not significant on grass-litter carbon mineralization efficiency. Alternatively, nanoparticles application significantly reduced mineral nitrogen content in litter-amended soil in both time intervals. Therefore, nitrogen mineralization efficiency was decreased to 60% after 180 days compared to that after 90 days in nanoparticles grass-litter amended soil. These effects can be explained by the presence of labile Fe in microbial biomass after 180 days in nanoparticles amendment. Hence, our results suggest that toxicity of IONPs to soil functioning should consider before recommending their use in agro-ecosystems.