Determinación de triazinas en medio marino

Resumo

Triazines are one of herbicides groups most widely used for the control of weeds. Currently, they are considered environmentally dangerous because of their persistence, toxicity, bioaccumulation and being endocrine disruptors. Their indiscriminate use can be observed not only in soils, fruits and vegetables, but also in water when these pollutants are washed away by rain. After their application, a large amount remains in the environment and, because of their persistence and mobility, can reach the marine environment. Although there are no maximum limits regulated for most of the triazines in water, sediment or biota, the Directive 2013/39/EU calls the attention on the importance of monitoring emerging pollutants which are not considered in the control programs, but can have toxic effects. The European Union has included Simazine and Atrazine in the list of 33 priority substances in the Water Framework Directive (2000/60/EC), by way of Decision 2455/2001/EC. Moreover, the Directive 2008/105/EC sets the Environmental Quality Standards (EQS) for these compounds in surface waters and committees the Member States to set EQS for these compounds in sediments and biota at national level. Finally, the Directive 2013/39/EU adds Terbutryn to the list of priority substances. On the other hand, the Marine Strategy Framework Directive 2008/56/EC establishes, between descriptors of good environmental health, "contaminants in fish and other fishery products destined to human consumption should not exceed the levels established by Community legislation". In this way, the Regulation 396/2005/EC, relative to the maximum residue levels of pesticides in food and feed of plant and animal origin, sets limits for Simazine and Terbuthylazine in algae; however this Regulation has not established yet maximum levels for pesticides in aquatic animals. Regarding to it, the U.S Food and Drug Administration has set tolerance levels for pesticides, including Simazine, in fish and fishery products. Triazinic herbicides may be transformed by chemical and biological processes. Because of their mobility, the degradation products can reach water bodies more easily than triazines; therefore, the impact due to herbicides tends to be underestimated when only the triazines are analyzed, being necessary to include their main degradation products to obtain a better knowledge regarding herbicides pollution. Therefore, it is necessary to provide precise, effective, simple and quick analytical methods for these compounds. Thus, throughout this Thesis, analytical methodology for the determination of these compounds in seawater, sediment and biota at trace levels was developed. The proposed methods have improved the previous methodologies found in the literature, are sensitive, selective and simple, besides complying with Green Chemistry principles. Once analytical methods were validated, a sampling of seawater, sediment and aquatic biota (algae, fish, and mollusks) was held.