Heavy metal concentration variability
Introduction
In September 2015, one of the Millennium Development Goals of the United Nations Organization, I grant water a priority for all member countries, since, the water pollution rate caused by the anthropogenic alteration of the hydrogeochemical cycle of heavy metals can be estimated at 2000 million cubic meters per day. That is why several studies have been carried out which will allow us to have a global vision of what happens in the environment, allowing to establish prevention measures to minimize its deterioration.
Developing
So far it is known that four are the main routes through which heavy metals can enter the environment between these is weathering, anthropogenic activity, atmospheric deposition and finally the removillization of sediments, however the influence of anthropogenic activity , makes natural processes indirect metal carriers, facilitating the entry into the environment.
Once these elements enter the medium they follow mobility patterns, which can be summarized in four ways: mobilization to surface or underground waters, transfer to the atmosphere by volatilization, absorption by plants and retention of metals in the soil. Thus, metals with high volatility facilitate pollution by atmospheric transport, depositing in areas with low temperatures, by the action of cold condensation.
Palustres systems tend to store among the sedimentary strata the metals of both its basin and the atmosphere, however the presence of heavy metals in these systems will depend greatly on the geological characteristics of the area, as well as anthropogenic activity. In general, the basal heavy metal values are a reflection of the deepest strata of the sedimentation column.
This means that as the depth increases, the redox potential decreases, incorporating the metals into the main sediments, precipitating as insoluble sulphides and associating with faith and hydroxides of faith and mn. However, the mobility of the metal will not depend only on its chemical speciation, but on parameters such as pH, organic matter, carbonates etc. Metal adsorption can be carried out by clay minerals, oxides and hydroxides of faith, to and mn, giving different degrees of adsorption of metals to the ground among which is mentioned:
- Specific adsorption: faith oxides and are linked to an OH group, resulting in a closed structure
- Adsorption does not specify: in this case there is reversibility and forms an open structure
This is because the organic and mineral particles of the sediments have a high electrostatic activity as well as molecular forces, causing the adsorption of exogenous cations and molecule.
conclusion
The sediments are made up of organic and inorganic particles and interstitial water, the latter occupies about 80 % of the volume of a sediment tank, which due to its ionic composition is a useful tool to determine the degree of contamination of a certain area. Given its property to store metals and organic compounds, it is considered as a source of short -term pollution, under both physical, chemical, pH conditions, redox potential, microbial activity and temperature.
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