Contamination and Environmental Risk Assessment of Potentially Toxic Elements in Soils of Palm Farms in Northwest Riyadh, Saudi Arabia

Abstract

Thirty-four surface soil samples were collected from the palm farms of the Al-Ammariah area, northwest Riyadh, Saudi Arabia to assess the contamination and environmental risk of potentially toxic elements (PTEs). Aluminum (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), strontium (Sr), uranium (U), vanadium (V), and zinc (Zn) were analyzed using inductively coupled plasma–atomic emission spectroscopy (ICP–AES). Several pollution indices were employed to assess contamination and to evaluate the environmental risks of these PTEs. Average values (mg/kg) for Cr (19.97), Pb (5.08), Cu (11.36), Zn (52.16), Ni (26.94), Co (3.89), and V (18.94) were under the values recorded for soils globally, while the average values of Hg (0.50) and U (8.06) were greater than the average values of worldwide soils. Pollution indices indicated that the studied soils exhibited indications of severe enrichment and significant contamination with Hg, and moderately severe enrichment with U and As. The potential ecological (RI) findings indicated a moderate level of risk posed by PTEs in the study area. The potentially toxic elements originated from both natural and human sources, largely due to chemical weathering of the neighboring mountains, in addition to the widespread utilization of insecticides and fertilizers.