Um novo índice de qualidade das águas para proteção da vida aquática aplicado ao Rio Atibaia, região de Campinas/Paulínia-SP

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.

Contaminação de águas subterrâneas por pesticidas: avaliação preliminar

A discussion about groundwater contamination is presented in this work. Contamination by agricultural activity, more specifically by pesticides is emphasized. Indirect and direct estimates could be used to predict pesticide behavior in soil, and consequently, to evaluate the potential of groundwater contamination. These results could be applied to advise about the possibility of groundwater contamination by pesticides, and to provide subsidies for making decisions more quickly and efficiently.

Desempenho analítico de laboratórios prestadores de serviço na determinação de metais em águas

Analytical laboratories are expected to produce reliable results. Decision makers are guided in their actions (financial, legal and environmental) using analytical data provided by numerous laboratories. This work aimed to evaluate the analytical performance of Brazilian laboratories on producing trustworthy results. Nineteen laboratories, accredited and non-accredited ones, were contracted to analyze a USGS (United States Geological Survey) certified water sample for 17 chemical elements (mostly metals) without knowing the origin of the sample. Considering all the results produced, only 35% of them were valid. Three laboratories present satisfactory performances, whereas the majority showed a very poor overall performance. The outcomes of this work show the need for a more effective analytical quality program to Brazilian laboratories.

Sistema limpo em linha para extração em fase sólida de contaminantes emergentes em águas naturais

A solid-phase in-line extraction system for water samples containing low levels of emerging contaminants is described. The system was specially developed for large volume samples (up to 4 L) using commercial solid-phase extraction (SPE) cartridges. Four sets containing PTFE-made connectors, brass adapters and ball valves were used to fit SPE cartridges and sample bottles to a 4-port manifold attached to a 20 L carboy. A lab-made vacuum device was connected to the manifold cap. The apparatus is robust and less expensive than the typical available system. Its also provides less experimental handling, avoiding cross contamination and sample losses.

Variação sazonal da fotossíntese, condutância estomática e potencial da água na folha de laranjeira 'Valência'

Seasonal variation in environmental conditions may influence gas exchange rates as well as water relations in perennial species. This work was carried out to evaluate photosynthetic rates (A), transpiration (E), stomatal conductance (g) and leaf water potential (psi f ) in 'Valencia' orange trees grafted on four different rootstocks. Measurements were made twice a day: from 9h00 to 11h00 a.m. and from 1h00 to 3h00 p.m., during January, March and July. A and g were significantly lower and psif was significantly more negative, in the afternoon. The decrease in A may be related to the reduction in g, due to the increase in the vapor pressure deficit between the air and the leaf (VPDair-leaf ) in the afternoon, when temperatures are higher. In spite of the partial stomatal closure in the afternoon, the values for E were approximately the same as those measured in the morning, due to the increase in the VPDair-leaf . A decrease in A and g could also be noted from January to July, that is, from the hot and humid summer months, to the colder and drier winter ones. It was suggested that the decrease in A and g observed from January through March, may be related to the decrease in plant growth rates, which could have influenced the source-sink relationships, since the climatic conditions for both months were similar. The decrease in A and g showed in July, seems to be related to the decrease in both the night temperature and the growth rate of plants.