Dissemination of Heavy Metals and Tolerant Bacteria along Zarqa River (Jordan)

Zarqa River (ZR) is an important river basin in Jordan. However, it is continuously exposed to different types of pollutants including heavy metals. This study was carried out to determine the concentration of the following heavy metals in this vital environment: Pb, Cd, Cu and Zn and to enumerate, isolate and characterize the indigenous bacteria inhabiting this environment to test their heavy metal tolerance and bioremoval ability. Samples in this study include four different types: water, soil, sediment and three local plants (Nerium oleander, Phragmites australis and Nicotenia glauca) from 13 sampling sites assigned as A1-A13 starting from Kherbat Al-Samra treatment plant and ending at King Talal dam. High concentration of Pb was detected in water samples from site A1 (3200 mg L-1) as well as Cd from site A13 (2500 mg L-1). In soil, Zn was found at high concentrations in all sampling sites while Cd was found at high concentration only in site A12. High concentrations of Zn and Cu were detected in sediment samples from sites A1 and A8, respectively. In case of plant samples, Zn was detected at high concentration in Nicotenia glauca. A relatively high viable bacterial counts in site A12 soil and sediment samples were detected (2x1015 and 1.8x1014 CFU mL-1, respectively) and in site A13 water samples (6x1017 CFU mL-1). Identified bacteria belong to Staphylococcus, Escherichia, Lactobacillus, Bacillus, Pseudomonas, Micrococcus, Klebsiella, Enterobacter, Alcaligenes, Mycobacterium, Citrobacter, Corynebacterium, Acetobacter, Serratia and Salmonella. Among them, Corynebacterium sp., was the most effective in heavy metal bioremoval.