**Author details**

Hassan Al-Haj Ibrahim

Address all correspondence to: hasahi123@hotmail.com

Al-Baath University, Homs, Syria

### **References**

[1] Al-Haj Ibrahim H. Design of fractionation columns. In: Bennett K, editor. Matlab: Applications for the Practical Engineer. Intech; 2014. pp. 139-171


liquid (LC and capillary electrochromatography (CEC)), a gas (GC) or a supercritical fluid (supercritical-fluid chromatograph SFC). The stationary phase may be a thin layer of an adsorbent like silica gel, alumina or cellulose on a flat, inert substrate in thin layer chromatography (TLC) or a strip of chromatography paper in paper chromatography. Furthermore, the stationary phase may be as or on a plane in planar chromatography or the bed of the

The various components of the mixture to be separated travel at different speeds causing them to separate. Fractionation of the mixture components (the analytes or eluites) takes place by difference in affinity between the stationary and the mobile phases. Several mechanisms may be applied for the separation of the analytes such as ion exchange (in ion exchange chromatography) and size exclusion (in size exclusion chromatography, also known as gel permeation chromatography or gel filtration chromatography). In ion exchange chromatography, the analytes are separated based on their respective charges. In size exclusion chromatography, molecules are separated according to their size (or hydro-

Chromatography may be preparative or analytical, but only preparative chromatography is a form of separation. In chromatography, however, no phase transition is involved and even preparative chromatography may not therefore be considered a true fractionation process.

Other processes of separation that are mainly used for isotope separation include electromagnetism and laser separation. In electromagnetism, first used for the production of uranium-238, an ionic beam obtained from a uranium compound was passed through a magnetic field. Because the radius of the curvature of the path of the ions deflected by the beam depends on the mass of the ion, ions of different mass complete their path at different positions, and the uranium isotopes were appreciably separated. In laser separation, the isotope mixture is first vaporized and its atoms are selectively excited and ionized by an accurately tuned laser

[1] Al-Haj Ibrahim H. Design of fractionation columns. In: Bennett K, editor. Matlab:

Applications for the Practical Engineer. Intech; 2014. pp. 139-171

stationary phase may be in a tube in column chromatography.

dynamic diameter or volume).

10 Fractionation

*1.5.6. Other processes of separation*

**Author details**

**References**

Hassan Al-Haj Ibrahim

Al-Baath University, Homs, Syria

beam and the desired isotope is thus separated out.

Address all correspondence to: hasahi123@hotmail.com


**Chapter 2**

**Provisional chapter**

**Application of the Geochemical Fractionation of Metals**

The geochemical fractionation of metals in soils and sediments corresponds to a technique to evaluate the levels of contamination and their probability of transfer to bodies of water and biota. For environmental studies in water reservoirs, the results of geochemical fractionation added to physicochemical analysis of water, can define the environmental conditions of metal release. This chapter briefly presents the concept and some fractionation techniques, with emphasis on the BCR methodology, in conjunction with other analyzes of water from the bottom of the reservoir to evaluate the dynamics of Mn mobilization in the Riogrande reservoir in Colombia, as example of practical application of Geochemical Fractionation. The highest proportions of Mn in the sediments of the Riogrande II reservoir were found in the exchangeable fraction and associated with carbonates, however the diffraction analysis did not find carbonated phases. It was concluded that the Mn in the water of the bottom of the Riogrande II reservoir originated especially by processes of desorption of Mn, in addition to reductive dissolution

**Keywords:** geochemical fractionation, sediments, BCR protocol, metal mobility, Mn

The geochemical fractionation methodology allows establishing the proportions of groups, fractions or different forms of metals associated with materials such as soils, sediments and sludge, however it is necessary to combine these results with other analyzes such as mineralogical analysis, diffractometry, geoavailability, bioaccessibility and bioavailability analysis,

**Application of the Geochemical Fractionation of Metals** 

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

DOI: 10.5772/intechopen.76223

**in Sediments for Environmental Analysis of a Water**

**in Sediments for Environmental Analysis of a Water** 

**Reservoir. Case Riogrande Ii (Antioquia - Colombia)**

**Reservoir. Case Riogrande Ii (Antioquia - Colombia)**

Juan Pablo Salazar Giraldo

Juan Pablo Salazar Giraldo

**Abstract**

of oxyhydroxides.

**1. Introduction**

dynamics in sediment-water interface

http://dx.doi.org/10.5772/intechopen.76223

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

#### **Application of the Geochemical Fractionation of Metals in Sediments for Environmental Analysis of a Water Reservoir. Case Riogrande Ii (Antioquia - Colombia) Application of the Geochemical Fractionation of Metals in Sediments for Environmental Analysis of a Water Reservoir. Case Riogrande Ii (Antioquia - Colombia)**

DOI: 10.5772/intechopen.76223

Juan Pablo Salazar Giraldo Juan Pablo Salazar Giraldo

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.76223

#### **Abstract**

The geochemical fractionation of metals in soils and sediments corresponds to a technique to evaluate the levels of contamination and their probability of transfer to bodies of water and biota. For environmental studies in water reservoirs, the results of geochemical fractionation added to physicochemical analysis of water, can define the environmental conditions of metal release. This chapter briefly presents the concept and some fractionation techniques, with emphasis on the BCR methodology, in conjunction with other analyzes of water from the bottom of the reservoir to evaluate the dynamics of Mn mobilization in the Riogrande reservoir in Colombia, as example of practical application of Geochemical Fractionation. The highest proportions of Mn in the sediments of the Riogrande II reservoir were found in the exchangeable fraction and associated with carbonates, however the diffraction analysis did not find carbonated phases. It was concluded that the Mn in the water of the bottom of the Riogrande II reservoir originated especially by processes of desorption of Mn, in addition to reductive dissolution of oxyhydroxides.

**Keywords:** geochemical fractionation, sediments, BCR protocol, metal mobility, Mn dynamics in sediment-water interface

### **1. Introduction**

The geochemical fractionation methodology allows establishing the proportions of groups, fractions or different forms of metals associated with materials such as soils, sediments and sludge, however it is necessary to combine these results with other analyzes such as mineralogical analysis, diffractometry, geoavailability, bioaccessibility and bioavailability analysis,

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

for a complete environmental study. In this chapter of the book "Fractionation", an explanation is given for the concept of Geochemical Fractionation, its importance, the BCR methodology and its application to the release of metals such as Mn in sediments, applied to the Riogrande II Water Reservoir in Colombia.

column, as in the water-sediment limit, however the abrupt decrease of the potential in the redoxcline is not due to the depletion of oxygen, but due to the appearance of reducing sub-

Application of the Geochemical Fractionation of Metals in Sediments for Environmental Analysis of a Water...

oxidizable metals forms predominate (reduced species), associated with organic and residual matter, while reducible (oxides) and interchangeable metals forms tend to be unstable and are easily solubilized [8]. Metals have a differential behavior in lentic or semilentic bodies of water where epilimnion oxygen-rich conditions predominate. It forms oxidized species (reducible metal forms), which tend to be insoluble and precipitate forming a sediment rich in oxidized solid phases (M3+ or M4+), likewise other minerals such as clays with their negative charge, transport on their surface metals, forming complexes of external surface, which can also be submerged in the reservoir. At the bottom of the hypolimnion and sediment, the anoxic and reducing conditions, as well as biological processes, release it in the form of reduced (M2+), complex and soluble species, whose oxidation process is very sensitive to heterogeneous and homogeneous catalysis, and it is dependent on pH and dissolved oxygen. This process is accelerated by the presence of microbial catalysis through different stages; it has been found that in the sediment, the movement of ions such as Mn and Fe towards the water column may

S formation [9, 10].

The redox conditions can influence the behavior of the trace metals in sediments and affect the proportions of the metals forms, either directly or indirectly through changes in the oxidation states of the ligands capable of complexing the metal; for example, changes in the redox conditions can cause the reductive dissolution of mineral species that have some adsorbed metals (oxyhydroxides that can be reduced and desorb metal ions): ORP-Eh values higher than +414 mV are considered oxic and oxidizing, the probability of metal release is low; ORP-Eh values between +414 and + 120 mV indicate sub-toxic, moderately reducing conditions, under these redox potentials the species are controlled by the redox reactions of Mn and Fe [11], ORP-Eh between +250 and +100 mV, the metal oxyhydroxides are unstable and the process of dissolution of most metal oxides begins, and ORP-Eh values lower than −120 mV, the sediment is considered anoxic [11, 12]. If the oxidized layer is less than 5 cm, it is considered that the sediment is dominated by Mn2+ flow, the difference with the standard value of reduction of Mn (+526 mV), it is because this value is referenced to a pH = 7.0 and T = 25°C, while a value

In natural systems, the release and mobilization of metals normally occurs through soluble phases; so, the evaluation of the contamination of a soil or sediment cannot be based on its total concentration of the metal, since the potentially contaminating from metals depends on the chemical form or geochemical fraction in which the metal is found. In addition, the dissolved metal cations are subject to several mobilization or fixation processes depending on factors such as pH, ORP-Eh, presence of both soluble and insoluble organic matter, and ionic strength [13, 14]. The release, mobility and toxicity of metals depends both on the proportions of them in the geochemical fractions and the environmental conditions at the bottom of a body of water (pH, ORP-Eh, DO, OM and EC), [15–20]. However, several authors have shown the co-precipitation of some metals in the form of complexes with solid

S), [7]. In general, in sediments under anoxic conditions,

http://dx.doi.org/10.5772/intechopen.76223

15

stances such as hydrogen sulfide (H<sup>2</sup>

be coupled with an eventual and possible H2

of +414 mV is more appropriate under environmental conditions.

**2.2. Release of heavy metals and water contamination**

fractions [21].
