**2. Source of contamination in water**

The presence of these heavy metals on the surface of the water can be due to natural or anthropogenic activities. In natural activities, weathering of rocks that contain metals, an eruption from volcanos, fires in the forest, and naturally occurring processes of weathering can be included. From these activities, metal enters the different sections of the environment. Heavy metals can be found in the forms of sulfates, hydroxides, oxides, sulfides, phosphates, and silicates [12, 22]. A huge amount of accumulation of heavy metals into the water is mainly due to anthropogenic and natural activities. Some more examples of natural source through which heavy metals contaminates water are, wet and dry deposition of atmospheric salts, water-rock interaction, or water interaction with the soil. While the sudden increase in urbanization and industrialization are an example of anthropogenic sources through which water get contaminated (**Table 2**; **Figure 1**) [23].
