Agriculture Reference
In-Depth Information
Vicia faba (broad bean) and Zea mays (corn) are also commonly used in the assessment of soil
toxicity, particularly for cytotoxicity, genotoxicity and mutagenicity assays (White &
Claxton, 2004).
In a biological system, the sequential order of alterations promoted by the presence of
pollutants occurs in crescent levels of biological organization, extending from the molecular or
biochemical level to the physiological or individual level, until the population and ecosystem
level (Stegeman et al., 1992). When a significative alteration is evident, the ecosystem must be
already severely damaged. Therefore, techniques that show responses at lower levels of
biological organization are considered more preventive (Nascimento et al., 2008).
Morphological alterations can be used as biomarkers in toxicity investigations of specific
chemical compounds and in the monitoring of the acute and chronic effects of organisms
exposed to impacted environments. In this context, the morphological analysis of target
organs, carried out by ultra-morphology, histology and ultrastructure, has become widely
used in studies with invertebrates, aiming to identify different damages caused by harmful
substances to the organisms (Fontanetti et al., 2010).
Another tool that has shown to be increasingly efficient in the assessment of soil toxicants on
the organisms is the use of molecular biomarkers. Recent studies show great interest in the
use of enzymatic biomarkers as a form to monitor the environment, since the increase or
inhibition of the activity of certain enzymes can explain a possible response to the
environment stress.
Due to the importance to ensure the genetic integrity of the organisms, biomarkers of
genotoxicity are gaining attention in the evaluation of the toxic potential of soil samples
(Misik et al., 2011). The tests used in the genotoxic assessment of an agent (genotoxicity and
mutagenicity tests), include the Ames test, chromosome aberrations test, micronucleus test,
comet assay, SMART test (Somatic Mutation and Recombination Test), microarray and
microscreen, using techniques of cellular, molecular and genetic biology both in vitro and in
vivo , in situ and ex situ .
Given the above, the aim of the present chapter was to compile and discuss information
present in the literature about the use of animal and plant bioindicators in the analysis of
soil toxicity, as well as characterize the different biomarkers used in these organisms that
enable the assessment of the soil toxicant effects in different levels of the biological scale, i.e.,
morphological, biochemical and genotoxic.
2. Complex substances, organic compounds and metals: potential soil
contaminants
Population growth combined with the increasing industrialization is responsible for
generating tons of waste per day, which, many times, are accumulated in the environment
without any previous treatment. Soil becomes a cheaper and practice alternative for the final
disposal of these residues, but not without consequences. Soil contamination is a broad
problem, since the contaminants can be leached into groundwater, rivers and lakes. The
major xenobiotics responsible for the contamination of this compartment as well as their
implications for invertebrates and plants will be discussed.
2.1 Vinasse
Among the substances released into the soil with toxic potential it can be cited the vinasse, a
product of the alcohol production, composed by water (97%) and a solid fraction (organic
matter and mineral elements). According to Sahai et al. (1985), due to the fast growth of the
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