Avaliação dos níveis de cromo total em águas para consumo humano / Evaluation of total chromium levels in drinking water

Níveis elevados de cromo associados às águas naturais não são comuns, mas concentrações elevadas desse elemento, de ocorrência natural, têm sido relatadas nas águas subterrâneas de vários sistemas aquíferos, incluindo o Aquífero Bauru, SP, Brasil. Este fato está associado à ocorrência de rochas máficas/ultramáficas e às condições alcalinas e oxidantes. Neste estudo foi desenvolvido e aplicado um método para monitorar a concentração de cromo total em amostras de água da cidade de São José do Rio Preto. Esta cidade está localizada no estado de São Paulo, na região onde concentrações superiores ao limite estabelecido pela legislação brasileira (0,05 mg/L) foram detectadas em águas subterrâneas de poços de abastecimento. O cromo total foi determinado usando-se Espectrometria de Massas com Plasma Indutivamente Acoplado (ICPMS) em 104 amostras de água coletadas, entre 2013 e 2017, em diferentes pontos de distribuição (zona rural, residencial, distrito industrial, comercial, reservatório de distribuição e estação de tratamento de água), considerando-se 52 locais. Em 99 % das amostras as concentrações de Cr estavam acima do limite de quantificação calculado para o método (0,001 mg/L). E 15% apresentaram concentrações acima do limite de regulação na água potável (Portaria 2914/2011), sendo, portanto, consideradas impróprias para o consumo humano.

Elevated chromium levels in the natural waters are not common, but the high concentrations of naturally occurring Cr have been reported in the groundwater of several aquifer systems. This finding is linked with the occurrence of mafic/ultramafic rocks and associated with the alkaline and oxidizing conditions. This study aimed at monitoring the total chromium concentration in drinking water samples from São José do Rio Preto city. Cr concentrations higher than the limit established by the Brazilian Legislation (0.05 mg/L) were detected in the groundwater from the deep supply wells. Total chromium was determined by using an Inductively Coupled Mass Spectrometer (ICP-MS) in 104 samples collected from the public drinking water distribution networks in 52 sites, from 2013 to 2017. Cr concentrations above the method limit of quantification (0.001 mg/L) were found in 99% of the analyzed samples. Approximately 15% of the collected samples presented Cr in concentrations above the established legislation limit for drinking water (Ordinance 2914/2011), that should be considered as improper for consumption.

Evaluation of chemical and physical-morphological factors as potencial determinants of Biomphalaria pfeifferi (Krauss, 1848) distribution

This study was carried out in five sites along a small perennial river system in south-central Tanzania, which had been identified as the focus for transmission of intestinal schistosomiasis in the area. Malacological surveys preceding the study showed a focal distribution of Biomphalaria pfeifferi, intermediate host snail of Schistosoma mansoni, the snail being present in three sites but absent from the other two sites. The objective of this study was to evaluate to what extent chemical and/or physical-morphological factors determine the distribution of B. pfeifferi between these five sites. It was found that none of the chemical constituents in the waters examined were outside the tolerance range of B. pfeifferi snails. Moreover, the composition of water from B. pfeifferi-free sites was not different from that in those sites where snails occurred. Furthermore, none of the physical-morphological constituents seemed likely to be determinant for the absence of B. pfeifferi. In view of these findings, and those of previous studies, it is concluded that the focal distribuition of B. pfeifferi cannot be associated with a single environmental factor and is rather the result of more complex interactions of habitat factors.

Biogeochemical properties at the Jataí ecological Station Wetlands (Moji-Guaçu River, Säo Paulo, SP)

The relatively large number of scientific publications on natural and constructed wetlands around the world is due to the importance these areas have as critical sites where biogeochemical cycling of elements is extensive on a global scale. The understanding of ecological functions and community structure is highly dependent on the knowledge of those cycles and their interactions. These studies are also relevant because natural or constructed wetlands are sites used worldwide to treat industrial and domestic effluents. This paper reports on a series of studies performed and in progress at the Jataí Ecological Station (Moji-Guaçu river, Luiz Antonio, SP, Brazil) with emphasis on the main biogeochemical properties of aquatic systems found there (lacustrine and riverine). Results obtained during the last 10 years within the scope of the Jataí Project with its various subprojects is just beginning to permit understanding the high complexity of these ecosystems.

Trabajos presentados al Curso Taller sobre Control de Calidad Analítica

Enfoca generalidades del control de la calidad del agua y muestra criterios, guías y normas sobre agua potable. Analiza detalladamente las características físicas y químicas del agua, y los parámetros físico-químicos en su tratamiento. Trata de las pruebas de control en plantas de tratamiento. Presenta parámetros de calidad, métodos analíticos y equipos necesarios, criterios para selección de métodos, programa de control de calidad para un laboratorio de análisis de aguas, aspectos prácticos de la observación de parámetros. Señala los manuales de métodos para análisis químicos