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One hundred and eighty drinking water samples were collected from five zones of Riyadh governorate including Riyadh main zone, Ulia, Nassim, Shifa, and Badiah zones. The water was collected from the main water network and underground and upper household tanks in each zone. The water quality was found to be acceptable for drinking with respect to chemical characteristics; however, analyses exhibited some microbial contamination. The water quality index (WQI) is a mathematical method used to facilitate water quality explanation. The WQI was calculated using several physico-chemical and microbial parameters. The results showed that more than 88% of Riyadh main zone, 91% of Ulia, 97% of Nassim, 88% of Shifa, and 100% of Badiah waters zones were considered excellent for drinking (class I). The remaining waters were considered unsuitable for drinking (class V) due to microbial contamination.

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Industrial activities are associated with various heavy metals (HMs) being emitted into the environment, which may pose a threat to humans and animals. The rapid increase in an industrial activity in major cities in Saudi Arabia (SA) has raised concerns regarding the accumulation of HMs in the environment. The aim of this study is to assess the accumulation of HMs in soil and native plants in an industrial environment. We collected 36 surface soil samples and 12 plant species from 12 sites in an industrial city in central SA. The results showed that the HMs content in the soil followed a descending order of (Fe > Ni > Zn > Pb > Cu> Cr > Cd). The enrichment factor (EF) of HMs in the soil ranged from 0.20 to 7336. Up to 100%, 16.6%, and 6.2% of soil samples were extremely highly enriched with Cd, Ni, and Pb, respectively. Plant species Cyperus laevigatus accumulate Cd, Pb, and Ni. Citrullus colocynthis accumulate Cd and Pb in significantly (p < 0.001) higher amounts than other studied species. The Pollution Load Index (PLI) values for the 12 sites ranged from 0.52–1.33 with S5 and S2 PLI >1.0 indicating progressive deterioration of these sites. The Bioaccumulation Factor (BF) ranged from 0.04–2.76 and revealed that some plant species may be candidates for phytoextraction potential. The most promising plant species for phytoextraction and remediation were annuals or perennials such as Malva parviflora, Sisymbrium irio and Citrullus colocynthis, especially for Cr and Cu. This study suggests that these native plant species may be useful for phytoremediation in the area.

-at slightly high concentration. The water quality index (WQI) reveals that 94% of the samples were excellent for drinking (class I). While the remaining was unsuitable due to total coliform group contamination ''class (V)''. Durov diagram suggest no clear facies and dominant water type can be noted. It indicates mixing processes of two or more different facies might be occurring in the groundwater system. All studied waters were undersaturated with respect to halite, gypsum, fluorite, and anhydrite. These minerals tend to dissolve and increase water salinity. A direct relationship between Zamzam water salinity and rainfall is recorded. The water salinity fluctuated between 4500 mg L -1 (year 1950) and 500 mg L -1 (year 2015) based on rainfall extent. The approach applied can be used to similar groundwater worldwide.