In this paper a water quality index is developed to subsidize management actions in the Atibaia River for upon protection of aquatic organisms. This index is composed of two measurable environmental parameters normaly, ammonia and dissolved oxygen, the latter representing the contribution of organic matter. Concentrations of these two variables were normalized on a scale from 0 to 100 and translated into statements of quality (excellent, good, regular, bad and very bad). The index was applied to three monitoring points in the Atibaia River and compared to other indices used by the State of São Paulo Environmental Agency (CETESB). The results showed that the degradation in this watershed follows the urban population density. The developed index is more restricted than the other ones routinely used to infer water quality.

Neste trabalho são relatados vários processos de oxidação para a degradação de acetonitrila. Foram investigadas alternativas como fotólise, degradação com peróxido de hidrogênio, processos Fenton e foto-Fenton. A fotólise, o processo mais simples e de menor custo dentre os avaliados, promoveu 100% de degradação de soluções aquosas de acetonitrila a 20%, após 30 horas de irradiação. Este método apresenta, portanto várias vantagens dentre as opções a serem usadas em processos de decomposição de resíduos tóxicos de acetonitrila, os quais tendem a se acumular em laboratórios que utilizam equipamentos de Cromatografia Líquida de Alta Eficiência com Fase Reversa.

Several oxidation processes were investigated to degrade residues of acetonitrile. Alternatives such as photolysis, degradation with hydrogen peroxide, Fenton and photo-Fenton processes were investigated. Among the options studied, photolysis proved to be the best choice. Photolysis promoted 100% degradation of 20% aqueous acetonitrile solutions in 30 hours. This method proved to be a cheap alternative to decompose toxic residues of acetonitrile, which tend to be accumulated in laboratories that use RP-HPLC equipments.

Defining environmental chemistry is a not an easy task because it encompasses many different topics. According to Stanley E. Manahan, author of a classical textbook of Environmental Chemistry, this branch could be defined as the one centered in the study of the sources, transport, effects and fates of chemical species in the water, soil, and air environments, as well as the influence of human activity upon these processes. More recently, new knowledge emerged from the Environmental Toxicology allowed to go even deeper in the meaning of 'effects' and 'fates' of a continuous growing number of organic and inorganic species disposed in water bodies, soils and atmosphere. Toxicity tests became an important tool to evaluate the environmental impact of such species to a great number of organisms, thus allowing to set quality criteria for drinking water, sediments and biota. The state of art shows that environmental chemistry is a multi-inter disciplinary science by nature; therefore, it needs more than a limited, unique-approach and non-oriented set of data to understand the nature of natural processes. Taking all these aspects into consideration, one can say that Environmental Chemistry in Brazil is now a well established area of research within the classical areas of the Chemistry, with a large number of emerging groups as well research groups with worldwide recognition.