الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Lake Qarun, one of the inland lakes, is experiencing an increase in salinity levels and sewage discharge due to population growth and insufficient infrastructure. Lake Qarun receives an enormous volume of sewage and agricultural runoff, estimated at 400 x 106 m3/year. The influx of water is predominantly derived from two principal drainage systems, specifically EL-Batts (41%) and El-Wadi (36%), while the remaining 23% is attributed to smaller drainage systems. Consequently, Lake Qarun has been subjected to protracted exposure to both organic and inorganic pollutants for a considerable duration. The removal of heavy metals and trace elements from contaminated water bodies and land is necessary to establish an environment that is beneficial to human life. Bioremediation is often considered one of the best options since it is less dangerous, cleaner, cheaper, and friendlier to the environment than other methods. Therefore, the aim of this study was to produce up-to-date maps for Qarun Lake to monitor pollution with the help of remote sensing and GIS. Moreover, to isolate bacteria that are able to remediate some heavy metals.
In this study, 18 samples were collected from distinct locations within Qarun Lake to conduct bacteriological and physicochemical analyses. In situ measurements were carried out, which included measuring the physicochemical parameters of water quality using the EUREKA Manta2 device. The results of physicochemical parameters showed that the temperature values varied from 19.3 to 22°C, pH values from 7.5 to 8.9, EC from 16.9 to 57.3 mS/cm and turbidity from 9.2 to 51.9 NTU. Dissolved organic matter in water fluctuated between 1.5 and 4.53 mg/L.
Four toxic heavy metals (Pb, Ni, Cd and Cr) were assessed in the surface water of Qarun Lake. The high metal content in Qarun Lake water was mainly in the form of Pb, Ni and Cd. Pb ranged from 0.22 to 0.62 mg/L with a mean value of 0.42 mg/L, while Ni fluctuated from 0.05 to 0.31 mg/L with a mean of 0.25 mg/L and Cd fluctuated from 0.03 to 0.1 mg/L with a mean of 0.07 mg/L. However, Cr values do not exceed the EPA threshold limit, where concentrations ranged from 0.02 mg/L to 0.06 mg/L with a mean range of 0.05 mg/L. The spatial distribution of metals was similar since their levels are increasing from east to west and are closely correlated with salinity levels in the Lake. The WQI values of Lake Qarun water ranged between 84.33 and 305.53. The general average value of WQI showed that Lake Qarun water recorded 267.58 (Unfit) for aquatic life protection.
A total of 50 bacterial isolates, recovered from Qarun Lake, exhibited the heavy metal resistance potential to the existence of heavy metals in the lake. Six of them were able to tolerate high concentrations of heavy metals. These isolates were identified as Bacillus altitudinis, Bacillus cereus, Pseudomonas oleovorans, Streptomyces thermolilacinus OR397132, Enterococcus hirae OR397133 & Actinokineospora fastidiosa OR397131. Bacillus altitudinis was capable of removing Pb, Ni & Cd with efficiencies 89.74, 89 and 61.5 %, respectively, while Bacillus cereus could remove 59.9%, 83% & 79.4 of Pb, Ni and Cd, respectively. Pseudomonas oleovorans is a novel cadmium-resistant strain that has the ability to remove 87.5%, 89% & 72% of Cd, Pb and Ni, respectively.
Enterococcus hirae OR397133 and Pseudomonas oleovorans which can resist high concentrations of heavy metals has been reported as pathogenic bacterium responsible for multiple diseases in Mugil cephalus and Tilapia zillii which are the predominant fish species in Qarun Lake. Streptomyces thermolilacinus OR397132 can tolerate up to 1500 mg/L Pb 250 mg/L Ni & 300 mg/L Cd. The presence of Streptomyces sp. acts as bioactive against fish and shellfish pathogens. Actinokineospora fastidiosa OR397131 can resist multiple heavy metals up to 300, 90 & 40 mg/L Pb, Ni and Cd, respectively.