Abstract
This paper aimed to study the anomalous fluctuation of halogens with respect to the pollution status in surface water (w), pore water (p), and sediments (s) of Lake Mariout. It provided a framework for understanding the distribution of dissolved and precipitated halogen salts related to the pollution status of the lake. The study cleared out that bromide was only the most abundant halogen in the three studied partitions. On contrast, sediment’s partition contained the lowest chloride content. Fluoride minerals, especially, fluorapatites and carbonate-fluorapatite (FAP and CFAP), had high Saturation Index (SI) values in surface water (42.77–51.95 and 16.04–60.89, respectively) and in pore water (51.26–54.60 and 17.52–78.33, respectively). Bromide and chloride were mainly found in the soluble forms in the surface water and pore waters. Iodide salts, (Ca(IO3)2 and Ca(IO3)2.6H2O), were moderately precipitated in surface and pore waters. Thus, SI content reflected that halogens, especially fluoride and iodide, played a vital role in reducing lake pollution. Fluorite (CaF2) and sellaïte (MgF2) could only be formed in pore water, while calcite and aragonite could be deposited from surface water. In addition, Cl was mainly found in the forms of NaCl, CaCl2, MgCl2, and KCl in surface and pore waters. The multivariate analysis revealed that fluoride precipitate may serve in decreasing the dissolved salt pollution. Multivariate analysis showed that in the long run, the fluoride precipitation in FAP and CFAP can significantly adsorb and absorb various pollutants and can protect the lake from pollution. The ecological risk assessment conducted by calculating the enrichment factor (EF) showed that the lake was still unpolluted. Regarding human health risks, at appropriate levels of human health and safety, the hazard quotient (HQ) and hazard index (HI) of halogens found to be lower than these reported levels. Hence, ingestion and dermal absorption routes of halogens by surface water and sediments did not pose any adverse effects to population reflecting uncontaminated status of Lake Mariout.
Highlights
Introduction e water ecosystem inEgypt is rapidly deteriorating due to the increased discharge of heavily polluted domestic sewage, agricultural runoff, and industrial wastewater generated by human activities [1,2,3,4,5,6,7,8,9,10]
Distribution of Halogens in Surface Water. e range and average value of halogens in the surface water in this study show a sequence of Clw > Brw > Fw > Iw (Table 2 and Figure 2). e current study indicate that the water sample of pumping station attained high concentrations of fluoride (2.8 mg L−1), chloride (3887.8 mg L−1), and bromide (18.1 mg L−1), and low iodide (6.41 μg L−1) contents (Figure 2)
High levels of F, Br, and I are detected in the Main Basin region which is affected by the drainage of El-Qalaa and El Umoum containing the agricultural and industrial wastes
Summary
En, one-third of each extracted pore water sample was preserved in a brown polyethylene plastic bottle with a stopper and kept at −20°C for halogen determination. Calcium and magnesium in surface and pore waters and digested sediment samples were carefully determined by the titrimetric method using Eriochrome Black T and Murexide indicators [43]. Silicate was measured in the surface and pore waters and digested sediment samples by the calorimetric method [39]. E turbidity method was used to estimate sulfate in the surface water and pore water and digested sediment samples [43]. E dissolved salts in the surface and pore waters in the investigated area were utilized by Palmer’s method and piper ternary diagram.
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