**1. Introduction**

Heavy metals in aquatic environments have mainly a natural origin due to the geological parent material (lithogenic), they can be incorporated into different materials as silicates, carbonates, oxides, hydroxides, and sulfides structures and as a native element. They also could result from anthropogenic sources including deposition of particles (<30 μm in diameter) and precipitation containing heavy metals, fertilizers application, the use of agrochemicals, spilled of wastewater and mining waste [1, 2]. Among anthropogenic sources, ancient mine residues, has a

high impact and pose a threat to the environment and health as a consequence of the rustic extraction method and their high content of heavy metals such as arsenic (As), lead (Pb), cadmium (Cd), mercury (Hg), copper (Cu), zinc (Zn) and Iron (Fe), which can cause high damage to aquatic biota and human health [3, 4].

Metals are partitioned among the various aquatic environmental compartments (water, suspended solids, sediments and biota) and can occur in dissolved, particulates or complex form. The metals and metalloids can reach the aquatic environments from mining waste as metallic ions and complexes in dissolved solid formed either by weathering, erosion and run off processes. Once a metal reaches an aquatic reservoir, it does not suffer any degradation, rather they are accumulated in sediments and depending on their chemical form it can increase or reduce their toxicity, bioavailability, and solubility [5–7].

Sediments are considered a main sink and means of transport of organic and inorganic pollutants in aquatic environments. It has been found that they have a great capacity to adsorb metals and metalloids present in the aqueous phase and reduce their mobility in the aquatic environment [3, 8, 9]. Among different particles size that constitute sediments, metals are mainly associated with the smallest particles of colloidal size ranging from 0.001 to 0.1 μm in diameter due to their largest surface area and most likely as a consequence of occurrence of ionic exchange sites linked to several chemical species such as humus Fe, Al and Mn, oxyhydroxides, aluminosilicates and some moderately soluble salts such as calcium carbonate (CaCO3).

The mobility of trace elements, from the vadose zone to the aquifers and in rivers and tributaries, also influenced by sorption, oxidation–reduction, hydrolysis, and complexation and chelation processes, determining the transport of highly toxic metals and metalloids in aquatic environments [1]. Adsorption is likely the most important process that determines the mobility of traces metals in aquatic environments, since it supports ions at the interface between the solid and the aqueous phase, the clay and humus material with a negative charge on its surface adsorbs cations, while oxyhydroxides with varying charges on their surface can adsorb cations and anions, respectively.

Hence, this work aims to review the processes and mechanism involved in the dynamics (fate and transport) of heavy metals from mining-waste to aquatic compartments and the methods used for identification of chemical species associated with their mobility and ecological risk.
