Environmental Engineering Reference
In-Depth Information
3
Sediment characterization
Edson Campanhola Bortoluzzi
1
, Maria Alice Santanna dos Santos
2
& Marcos Antonio Villetti
2
1
Passo Fundo University, Brazil
2
Federal University of Santa Maria, Brazil
3.1 Introduction
ment production. Despite the fact that a sediment
contains a range of particle sizes, its mineralogy is
mainly based on silicates (Si
4
+
in a lattice). The
layered silicates, called phyllosilicates, are the most
common and important minerals in soils and thereby
in sediments. Some structure-related properties of
phyllosilicates, such as the specifi c surface area and
the ion-exchange capacity, give rise to the different
affi nities between sediments and pollutants, which
are responsible for the sediment sorption capacity
(Schulze 1989). Thus, the characterization of sedi-
ments and an understanding of their properties aid
researchers in predicting the behavior of sediments
(Horowitz 1991; Lin
et al.
2002; Citeau
et al.
2006).
Sediments' properties can be determined with rela-
tively simple analytical techniques using well-known
methodologies. However, sediment characterization
should be undertaken by understanding the particles
they comprise, such as their particle size distributions
and mineralogy.
Careful construction of a sampling strategy and an
understanding of the temporal and spatial variations
in sediment concentration and makeup, as well as
preparation of samples for analysis, are essential for
rigorous characterization of the sediments (Bortoluzzi
& Poleto 2006). Minerals and organic particles are
capable of complex associations, such as aggregates
of oxide-clay minerals or of microorganisms and
minerals, which demonstrates this complexity and
the necessity for an interdisciplinary approach
(Chenu 2001; Chenu & Plante 2006).
Relating particle size information and the minera-
logical nature of fi ne particles composing the sedi-
ment is a basic strategy to understanding their
behavior and properties, and ultimately their origin
(Hsieh 1984), the forms of pollutants associated with
particles, and possibly prediction of their mobility
The landscape today, with its topography of valleys
and mountains, was mostly modeled by erosional
process. Water, as a vector of this process, is capable
of carrying materials in either suspended or dissolved
forms. Over geological time, sediments impact land-
surface evolution as products of the erosion of rocks
and soil, as well in the formation of new materials.
On the other hand, it is human activity that pro-
motes the production of sediments in urban areas, in
mining regions, or in areas under agricultural pro-
duction (Minella
et al.
2007; Poleto 2007).
Anthropogenic activities also facilitate the transport
of a signifi cant amount of various types of organic
and inorganic pollutants from terrestrial to aquatic
systems, namely pesticides, nutrients, heavy metals,
and microorganisms (Accioly & Siqueira 2000).
Thus, human activity over the land negatively affects
the quality of the soil, water, and, therefore, the
function of natural ecosystems (Gonçalves
et al.
2005). The main consequences associated with
excess sediments are eutrophication, siltation of
lakes and rivers, high costs associated with treating
potable water, and public health problems due to the
presence of pathogens and pollutants.
Sediment is composed of particles that are hetero-
geneous in their form, size, and nature, sourced from
sites with a variety of geological and pedological
contexts and different soil management (Stumm
1993; Minella
et al.
2007; Bortoluzzi & Petry 2008).
According to FAO-WRB (2006), there are 31 groups
of soils in the world, each with the potential for sedi-
