B11G-0512
The Response of Sediments and Dissolved Organic Matter to Rapid Rainfall in the Santa Maria da Vitoria Watershed, Espírito Santo, BR
Monday, 14 December 2015
Poster Hall (Moscone South)
Nicholas D Ward1, Luciano Firme de Almeida2, Genswesley Dias3, Rebekka Gould4, Amanda Tan4, Thomas S Bianchi1, Alex V Krusche5, Richard G Keil4, Jeffrey E Richey6 and PCGAP, (1)University of Florida, Geological Sciences, Ft Walton Beach, FL, United States, (2)Companhia Espírito Santense de Saneamento, Vitoria, Brazil, (3)SECRETARIA DE ESTADO DO MEIO AMBIENTE E RECURSOS HÍDRICOS, Vitoria, Brazil, (4)University of Washington, Seattle, WA, United States, (5)CENA Center for Nuclear Energy in Agriculture, Piracicaba, Brazil, (6)University of Washington Seattle Campus, Seattle, WA, United States
Abstract:
The Santa Maria da Vitória River supplies over 30% of the water for the greater Vitória, Espírito Santo, BR metropolitan area, which has a population of roughly 1.6 million people. The availability of clean freshwater is severely limited during periods of heavy rainfall because water sanitation facilities are “clogged” by high sediment discharge. The headwaters of the Santa Maria da Vitória River are characterized by relatively pristine forested environments, transitioning into primarily agricultural and rural land uses, and finally reaching the large urban center of Vitória near its marine receiving waters. The discharge of suspended sediments and dissolved organic matter (DOM) was examined at a 3 hour frequency during heavy storm flows from October 2013 to May 2015 in the Santa Maria da Vitória River main channel and a small tributary, the Mangaraí River. Bulk isotopic analyses were used to determine potential sediment sources and whether specific landscape/land use features were functionalized during periods of high runoff. Likewise, time of flight mass spectrometry (GC-ToF-MS) was used to identify a broad suite of DOM compounds that responded positively with river discharge in an effort to determine the influence of land use on the delivery of dissolved components to the river. For example, the abundance of compounds related to specific agricultural settings increased during storm flow along with anthropogenic DOM sources such as plasticizer and pesticide-derived compounds. Suspended sediment concentrations increased by as much as 70 times during peak river discharge relative to base flow several days earlier with similar increases in particulate organic carbon and nitrogen observed. Results from this study and previous field measurements were integrated into a coupled hydrology-sediment transport model, DHSVM, as part of a dynamic information framework with the goal of predicting water/sediment discharge to inform management and policy sectors of the state of Espírito Santo.
