Nutrient reference concentrations and trophic state boundaries in subtropical reservoirs

Autor(es)

Cunha, D. G. F. ^[1] ; Ogura, A. P. ^[1] ; Calijuri, M. D. C. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Engn Sao Carlos, Dept Hydraul & Sanit Engn, BR-13566590 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: WATER SCIENCE AND TECHNOLOGY; v. 65, n. 8, p. 1461-1467, 2012.
• Citações Web of Science: 14

Resumo

Nutrient criteria as reference concentrations and trophic state boundaries are necessary for water management worldwide because anthropogenic eutrophication is a threat to the water uses. We compiled data on total phosphorus (TP), nitrogen (TN) and chlorophyll a (Chl a) from 17 subtropical reservoirs monitored from 2005-2009 in the Sao Paulo State (Brazil) to calculate reference concentrations through the trisection method (United States Environmental Protection Agency). By dividing our dataset into thirds we presented trophic state boundaries and frequency curves for the nutrient levels in water bodies with different enrichment conditions. TP and TN baseline concentrations (0.010 mg/L and 0.350 mg/L, respectively) were bracketed by ranges for temperate reservoirs available in the literature. We propose trophic state boundaries (upper limits for the oligotrophic category: 0.010 mg TP/L, 0.460 mg TN/L and 1.7 mu g Chl a/L; for the mesotrophic: 0.030 mg TP/L, 0.820 mg TN/L and 9.0 mu g Chl a/L). Through an example with a different dataset (from the Itupararanga Reservoir, Brazil), we encouraged the use of frequency curves to compare data from individual monitoring efforts with the expected concentrations in oligotrophic, mesotrophic and eutrophic regional systems. Such analysis might help designing recovery programs to reach targeted concentrations and mitigate the undesirable eutrophication symptoms in subtropical freshwaters. (AU)

• Processo FAPESP: 08/55636-9 - Contribuição ao conhecimento do ciclo do carbono no reservatório de Itupararanga como subsídio para a sustentabilidade da Bacia Hidrográfica do Rio Sorocaba (SP)
• Beneficiário: Maria do Carmo Calijuri
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 09/50842-2 - Heterogeneidade espacial e variabilidade temporal do reservatório de Itupararanga: uma contribuição ao manejo sustentável dos recursos hídricos da Bacia do Rio Sorocaba (SP)
• Beneficiário: Davi Gasparini Fernandes Cunha
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 11/12278-8 - Concentrações basais de nutrientes e metais na água de rios e reservatórios do estado de São Paulo: uma contribuição para a gestão integrada dos recursos hídricos
• Beneficiário: Allan Pretti Ogura
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica