Agriculture Reference
In-Depth Information
distilleries, there was, consequently, an increase in the amount of this residue, which was
traditionally discharged in open areas or next to water courses, causing air, water and soil
pollution. For Junior et al. (2008), the reuse of previously treated vinasse as fertilizer or soil
conditioner becomes an alternative of great interest. However, Lyra et al. (2003) affirm that
there are only few studies that evaluate its pollutant potential on soil and groundwater.
Thus, studies about the effects of vinasse application in the soil have been developed by
researchers of different countries. Recently, Brazilian researchers have studied the
genotoxicity and mutagenicity of vinasse applied
in natura
in the soil or associated with
other compounds. Souza et al. (2009) used
A. cepa
to evaluate the mitotic and chromosome
abnormalities resulted from exposure to landfarming soil treated with vinasse, used as a
possible bioremediator. According to the authors, the vinasse was responsible for
potentiating the clastogenicity of the landfarming by decreasing the pH and, thus, making
available the metals that were strongly adsorbed in the organic matter of the soil.
Other studies on the vinasse toxicity were conducted by Christofoletti and Fontanetti (2010)
and Pedro-Escher and Fontanetti (2010) also using
A. cepa
as test organism. In the first study,
the preliminary results show that the vinasse did not present cytotoxicity nor mutagenicity,
but it presented genotoxic potential when applied
in natura
or associated with sewage
sludge samples; the second study showed that different concentrations of vinasse diluted in
water (12.5%, 25% and 50%) presented genotoxic potential and only the raw vinasse
presented mutagenic potential, thus suggesting that the vinasse can cause damages in the
genetic material of certain organisms.
2.2 Sewage sludge
Another residue with pollutant potencial and problems in final disposal is the sewage
sludge generated in the STSs (Sewage Treatment Stations). Its great production, mainly in
the large urban centres, has led researchers to intensify the studies about the use of these
waste with agricultural purposes. Therefore, recycling, via agriculture use, presents itself as
a global trend (Lopes et al., 2005).
Nevertheless, sewage sludge can present, in its composition, undesirable chemicals (metals
and organic chemical compounds) and biological elements (pathogens) that, in contact with
man and/or fauna and flora, may cause contamination and diseases. Thus, any decision on
the most appropriate final destination depends on the evaluation and minimization of the
contamination risks of the environment and man (Rocha & Shirota, 1999).
Studies involving millipeds exposed to sewage sludge have shown that its components can
affect the integrity of organs such as the midgut of these animals (Godoy & Fontanetti, 2010;
Nogarol & Fontanetti, 2010, 2011; Perez & Fontanetti, 2011a). Mazzeo et al. (2010), using
A.
cepa,
investigated the genotoxic and mutagenic potential of domestic sewage sludge at
different concentrations.
2.3 Polycyclic aromatic hydrocarbons (PHAs)
Some of the main pollutants that cause concern in relation to soil contamination are the
PAHs (Bispo et al., 1999), which are compounds formed by two or more benzene rings,
exclusively constituted by atoms of carbon and hydrogen (Netto et al., 2000). There are
many origin sources but it can be highlighted industrial processes, such as petroleum
refining, combustion of organic matter and burning of coal (Page et al., 1999). According to
the IUPAC (International Union of Pure and Applied Chemistry) there are, currently, over
