The eutrophication history of a tropical water supply reservoir in Brazil

Autor: Luciane Fontana, Ana Luiza Spadano Albuquerque, Mark Brenner, Tatiani P. P. Sabaris, Denise C. Bicudo, Maria Aparecida Faustino Pires, Daniel Marcos Bonotto, Marycel Barboza Cotrim
Přispěvatelé: Instituto de Botânica, Universidade Federal Fluminense (UFF), University of Florida, Instituto de Geociências e Ciências Exatas, Unisanta, Cidade Universitária
Rok vydání: 2013
Předmět:
Zdroj: Scopus
Repositório Institucional da UNESP
Universidade Estadual Paulista (UNESP)
instacron:UNESP
ISSN: 1573-0417
0921-2728
1919-2010
DOI: 10.1007/s10933-013-9753-3
Popis: Made available in DSpace on 2022-04-29T08:44:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-01-01 Guarapiranga Reservoir is the second most important public water supply in São Paulo, Brazil and has been eutrophic for several decades. We inferred the major ecological shifts for the period 1919-2010 related to multiple stressors (forest flooding, hydrological change, use of algicide and eutrophication), using geochemistry (TOC, TN, TP, C/N, δ15N, δ13C) and diatom assemblages in a short (75-cm) sediment core. Thirty-two diatom species were abundant in the core and stratigraphically constrained incremental sum of squares analysis enabled identification of three diatom zones and four subzones, i.e. depths at which marked changes in species composition occurred. Early diatom assemblages were dominated by benthic, oligotrophic taxa, mainly Eunotia, influenced by flooded vegetation after dam construction. A shift to dominance by a planktonic species (Eunotia tukanorum) occurred ca. 1932, during the period of initial physical disturbance and early use of the water body as a public water supply. Diatoms and geochemical variables show that the reservoir was oligotrophic from ~1919 to 1947. Eutrophication began ~1975 and by the early 1980s the reservoir had become eutrophic, in response to an explosive increase in human population in the watershed. Severe cultural eutrophication has persisted since ~1990. Higher concentrations of copper in the sediments, beginning in 1991, reflect the increased use of copper sulfate to control cyanobacteria blooms and provide a chronological marker. Higher δ15N values in recent sediments indicate greater sewage inputs and low C/N values reflect the predominant contribution of algae to sediment organic matter. Eutrophic taxa Cyclotella meneghiniana and Nitzschia sp. dominate recent diatom assemblages, along with Aulacoseira granulata, a species that is tolerant of copper sulfate. Diatom assemblages reflect multiple stressors, however, geochemical information provides a better understanding of the early phase of the reservoir. Paleolimnologically documented trophic state changes in this important drinking water supply are largely attributable to increased urbanization of the drainage basin and inputs of sewage. Management efforts should focus on mitigating this nutrient source. © 2013 Springer Science+Business Media Dordrecht. Department of Ecology Instituto de Botânica, Av. Miguel Stéfano, 3687, São Paulo, SP, 04301-012 Departamento de Geoquímica Instituto de Química Universidade Federal Fluminense, Rua Outeiro São João Batista, s/n, Niterói, RJ, 24020-015 Department of Geological Sciences and Land Use and Environmental Change Institute University of Florida, Gainesville, FL, 32611-2120 Departamento de Petrologia e Metalogenia Instituto de Geociências e Ciências Exatas, Av. 24-A, 1515, Rio Claro, SP, 13506-900 Universidade Santa Cecília Unisanta, Rua Oswaldo Cruz, 277, Santos, SP, 11045-097 Centro de Química e Meio Ambiente IPEN-CNEN/SP Cidade Universitária, Av. Prof. Lineu Prestes, 2242, São Paulo, SP, 05508-000
Databáze: OpenAIRE
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