Determination of Some Heavy Metals in Tissues of Binni Mesopotamichthys sharpeyi and Water in Al-Dalmaj Marsh/Iraq

Abstract

The study was conducted in Al-Dalmaj marsh, considered one of the most important wetlands at the national and regional level and represents the most critical environment to form a good stock of Binni Mesopotamichthys sharpeyi in Iraq. The study assessed heavy metals in water and M. sharpeyi by detecting accumulation of (Nickel, Cadmium and Lead) in the tissues of gills, liver, and small intestines during the summer and winter seasons 2022-2023. The study results showed a high concentration of heavy metals in the water during summer compared to winter. Nickel levels ranged (0.19 ±0.627, 0.20 ±0.531) in water for both stations. The highest concentration was (1.339 mg/L) in suspended phase during summer, and ND in dissolved phase in winter, while Cadmium rates were (0.25±0.948, 0.17±0.478) in both stations respectively, the highest concentration was (1.827 mg/L) in suspended phase of station 1 during summer. Both stations ' lead rates were (0.39±1.455, 0.09±1.117). (3.176 mg/L) was the highest concentration in the suspended phase of station 1 during summer, while (0.121 mg/L) was the lowest in the suspended phase in winter. The results showed a sequence of concentrations of heavy metals in M. sharpeyi organs: Gills > Liver ≥ Small Intestines. The highest concentration rate of Nickel (4.109 & 3.692 mg/g) was recorded in small intestines and liver, respectively, during winter, the lowest rate (3.057 mg/g) was recorded in the gills during summer, the total of sedimentation rate of Ni in the liver and intestines was (3.726 mg/g), whereas (3.114 mg/g) in gills. Cadmium recorded an equal value of (0.957 mg/g) representing the highest percentage in the small intestines for both seasons. The highest concentrations (0.906 mg/g) in liver during summer. The total sedimentation rate of Cd in liver and small intestines was (0.852 mg/g), while (0.738 mg/g) was in gills. Lead recorded a high significant rate reaching to (8.501 mg/g) in gills during summer, followed by (6.115 mg/g) and (5.891 mg/g) in the liver and small intestines, respectively. Generally, lead reached the highest value for all elements assessed in fish at (8.501 mg/g) in the gills during summer, while (5.027 mg/g) was the highest rate in the liver during winter, and (3.709 mg/g) was the lowest rate in small intestines during winter. The total sedimentation rate of Pb in liver and small intestines was (5.185 mg/g), and (6.41 mg/g) was in the gills. Cadmium was recorded above the permissible (0.05 mg/g) limit by FAO [25] in the small intestine and liver, whereas lead exceeded the allowable limits (5 mg/g) by FAO/WHO [26]. Accordingly, the intake of these organs is unsafe for humans, and the registration of these high values poses a risk to the survival of this species as it can cause the death of fish in their environment under certain conditions.