Land treatment of crude oil is used by the oil industry, since it has been recognized that hydrocarbons (HC) can be metabolized by the indigenous microbial community of soil. The crude oil biodegradation in agricultural soil was studied for 12-mo to determine the HC biodegradation and leaching, the effect of HC on barley productivity and soil properties, and the potential for HC uptake in the plant. Concentration and composition of HC in the soil were periodically determined at a depth of 0 to 75 cm. The HC concentration decreased over time due mainly to the microbial degradation. At the end, 12% of the primary crude oil amount remained constant in the soil. A vertical migration, leaching and metabolic products of HC into subsoil occurred. The HC have changed soil fertility. Barley has been successfully cultivated in soil but the HC reduced some plant growth parameters. However, HC were not detected in plant seeds. Many of oil-utilizing bacteria and fungi were isolated from soil. The HC biodegradation potential of oil polluted soil (6% to 66%) were higher than of unpolluted one (4% to 53%). The bacteria (22% to 66%) were more active than fungi (4% to 46%) in HC biodegradation. The study demonstrated that agricultural lands with low rates of oil contamination allows the growth of plants. They ensure high efficiency of HC biodegradation. Vertical infiltration plays an important role in HC removing from soil. Alkanes were completely assimilated by microorganisms and polar compounds were more resistant to microbial attack.

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In the SAR, the oil-degrading bacteria (O-DB) are widespread, forming 8 % to 14 % of heterotrophic bacteria (HB). The O-DB numbers and biodegradability of petroleum hydrocarbons (PHY) are important in summer (SU) and sediments (SE) compared to winter (WI) and water (WA). The common O-DB retrieved from the SAR are Pseudomonas sp. (PS), Pseudomonas putida (PP), Pseudomonas fluorescens (PF), Pseudomonas aeruginosa (PA), Pseudomonas cepacia (PC), Corynebactrium sp. (CO), Bacillus sp. (BA), Bacillus cereus (BC), Bacillus subtilis (BS), Flavobacterium sp. (FL), Aeromonas sp. (AE), Arthrobacter sp. (AR), Vibrio sp. (VI), Nocardia sp. (NO), Acintobacter sp. (AC), Micrococcus sp. (MI), and Staphylococcus sp (ST). The most effective O-DB utilized more than 52 % of oil in 21-days. A mixed culture made of mutant PP+AR utilized 93 % of oil during the same period. The oil biodegradation rates in the SAR have been restricted by biotic and abiotic factors. By providing these factors to the oil-contaminated sites would improve the degradation rates. The biodegradation of n-alkanes was much faster than polycyclic aromatic compounds (PAC).

The present study has been achieved to estimate the acute toxicity effect of pesticide (endosulfan) (organochlorine) and its sublethal concentrations effect  on the oxygen consuming rate of three various snails species (Melanoides tuberculata, Radix auricularia and Theodoxus jordani) collected from Shatt Al-Arab river along the region extended from Abu-Al-Khasib to Garmat-Ali during 2018.  The 24 hr LC50 indicated that the M. tuberculata was more resistant, while R. auricularia and T. jordani were more effective to endosulfan and showed no difference. The study indicated that the employ of various species of snails, with their differing degree of sensitivity to the same toxicant, might be a useful tool in aquatic environmental toxicological investigations. The sublethal concentrations exposure (24 hr LC50) of pesticide had no considerable influence on the rates of oxygen consumption for each snail species. However, a decrease in the capability of snails to preserve respiratory independence through hypoxia was observed 24 hr after exposure to this dose.