Forensic Evaluation of Metals (Cr,Cu, Pb,Zn), Isotopes (δ13C and δ15N), and C:N Ratios in Freshwater Sediment |
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Authors: | Cristina Barazzetti Barbieri Jorge Eduardo Souza Sarkis Luiz Antonio Martinelli Isabella C A C Bordon Horst Mitteregger Jr Marcos Antônio Hortellani |
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Institution: | 1. Centro de Química e Meio Ambiente, Instituto de Pesquisas Energéticas e Nucleares (IPEN), Cidade Universitária , S?o Paulo, SP , Brazil;2. Instituto-Geral de Perícias, Secretaria de Seguran?a Pública do Rio Grande do Sul , Porto Alegre , RS , Brazil;3. Centro de Química e Meio Ambiente, Instituto de Pesquisas Energéticas e Nucleares (IPEN), Cidade Universitária , S?o Paulo, SP , Brazil;4. Laboratório de Ecologia Isotópica, CENA, Universidade de S?o Paulo , Piracicaba , SP , Brazil;5. Centro de Tecnologia do Couro do SENAI (Servi?o Nacional de Aprendizagem Industrial) , Estancia Velha , Brazil |
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Abstract: | A forensic approach was used to evaluate sediments from Portão Stream, including analysis of metals, carbon (C) and nitrogen (N) stable isotopes, and C:N ratios. Samples collected at various points located along the stream were tested in order to investigate a possible illegal leachate input. The studied stream is heavily impacted by sewage and industrial discharges from two cities along its course. Among the metals analyzed, chromium (Cr) was noticeably the main pollutant, showing the highest levels, above regulatory limits, downstream from some potential sources of effluents enriched with this metal. Isotope analyses revealed a general trend of depletion in the heavier isotope along the stream for C and N. The exception was one point near a hazardous waste landfill, where relatively more enriched δ13C and δ15N values were found. The isotope and metal analysis results indicated that this site was affected by a particular source, demonstrating the combination of these parameters could be used for the discrimination of sources in a heavily polluted stream. Nevertheless, further investigations are necessary to provide a comprehensive evaluation of the biogeochemical processes involved in the incorporation of leachate in sediments to use this analysis as evidence for the illegal leachate discharge. |
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Keywords: | sediment metals C and N isotopes C:N ratio |
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