The Cubatão River is one of the most important waterways of the coast of São Paulo. The continuous discharge of domestic and industrial effluents into the river and its tributaries resulted in loss of water quality across the system. Industrial and domestic landfills are also located around the studied area. The purpose of this study was to assess two aspects of sediments from the river and two of its tributaries (Perequê and Pilões Rivers): presence of trace elements and toxic metals, and ecotoxicity. Four sampling surveys were conducted from 2010 to 2011 on six different sites (here named P0, P2, P4, P5, P7 and P8). Ecotoxicity was assessed by exposing Hyalella azteca to the collected sediments. Instrumental Neutron Activation Analysis (INAA) and Atomic Absorption Spectrometry (GF AAS and CV AAS) techniques were applied for measuring concentration of metals and trace elements. The latter enabled quantification of Cd, Pb and Hg, while the former enabled quantification of a wide range of metals and trace elements. As, Cr and Zn concentrations obtained by INAA as well as AAS results were compared to threshold effect levels (TEL) and probable effect levels (PEL), the sediment quality guidelines proposed by the Canadian Council of Ministers of the Environment (CCME) for evaluating the potential effects on aquatic organisms. Cd and Hg values did not exceed TEL at the most of samples. Pb exceeded TEL at only one site campaign. As, Cr and Zn values exceeded TEL in most of sampling sites, with P2 and P4 showing the highest concentrations. Enrichment Factor (EF) and Geoaccumulation Index (IGeo) were calculated for the elements determined by INAA using North American Shale Composite (NASC) and regional background values. In short, As, Br, Cr, Hf, Pb, Sb and Zn were the elements found in concerning amounts, especially As, Br, Cr and Zn. Toxicity results revealed toxic effects on sediments from P2 and P5 (mortality > 50%). Body size analysis demonstrated negative effects at P4 (length smaller than 2,500.00 µm). Data crossing analyses indicate As and Br as main possible contributors to high toxicity levels.
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PROBABILITIES IN EXPERIMENTAL PHYSICS: EPISTEMIC LESSONS AND CHALLENGES
Probabilidades em Física Experimental: Lições Epistêmicas e DesafiosThales Borrely * Diana Taschetto ** Abstract: There is one way with which Nature responds to the questions we direct her about the correctness of our understanding of her ways: by means of experiments. In this paper, the pivotal role probability theory plays in experimental physics is presented: it allows us to combine observations that are seemingly analytically incompatible. The main concepts used for such task are introduced and explained. A brief historical sketch of the development of some of such concepts is drawn and it was used as a casestudy to defend the position that physics and philosophy are interlinked affairs. Some philosophical consequences of how the intrinsically probabilistic character of experimentation reverberates in our epistemic access of the world are also drawn.
Keywords:Probability; Measurement; Philosophy of Experimental Physics.Resumo: É por meio de experimentos que a Natureza responde às questões que a ela direcionamos sobre a adequação de nosso entendimento sobre seu funcionamento. O papel central que a teoria de probabilidades desempenha em física experimental é, neste artigo, apresentada: esta nos permite combinar observações que parecem, em uma primeira leitura, incompatíveis. Os conceitos principais utilizados para fazê-lo são introduzidos e explicados. Uma breve discussão histórica do desenvolvimento de alguns dos mencionados conceitos é indicada e utilizada como estudo de caso para dar suporte à posição que defende que física e filosofia são atividades entrelaçadas. Algumas consequências filosóficas acerca das implicações do caráter intrinsecamente probabilístico da experimentação para o nosso acesso epistêmico do mundo são, também, apresentadas. Palavras-chave: Probabilidade; Medição; Filosofia da Física Experimental.
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