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Precipitation and River Water Chemistry of the Piracicaba River Basin, Southeast Brazil
Author(s) -
Williams Michael R.,
Filoso Solange,
Martinelli Luiz A.,
Lara Luciene B.,
Camargo Plínio B.
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.303967x
Subject(s) - tributary , environmental science , hydrology (agriculture) , water quality , sink (geography) , drainage basin , precipitation , estuary , ecology , geology , oceanography , physics , cartography , geotechnical engineering , meteorology , geography , biology
Annual precipitation and river water volumes and chemistry were measured from 1995 to 1998 in a mesoscale agricultural area of southeast Brazil. Precipitation was mildly acidic and solute concentrations were higher in the west than in the east of the basin. Combustion products from biomass burning, automobile exhaust, and industry typically accumulate in the atmosphere from March until October and are responsible for seasonal differences observed in precipitation chemistry. In river waters, the volume‐weighted mean (VWM) concentrations of major solutes at 10 sites across the basin were generally lower at upriver than at downriver sampling sites for most solutes. Mass balances for major solutes indicate that, as a regional entity, the Piracicaba River basin was a net sink of H + , PO 3− 4 , and NH + 4 , and a net source of other solutes. The main stem of the Piracicaba River had a general increase in solute concentrations from upriver to downriver sampling sites. In contrast, NO − 3 and NH + 4 concentrations increased in the mid‐reach sampling sites and decreased due to immobilization or utilization in the mid‐reach reservoir, and there was denitrification immediately downriver of this reservoir. Compared with tributaries of the Chesapeake Bay estuary, the Piracicaba River is affected more by point‐source inputs of raw sewage and industrial wastes than nonpoint agricultural runoff high in N and P. Inputs of N and C are responsible for a degradation of water quality at downriver sampling sites of the Piracicaba River drainage, and water quality could be considerably improved by augmenting sewage treatment.