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Factors controlling nutrient concentrations in Amazon floodplain lakes 1
Author(s) -
Forsberg Bruce R.,
Devol Allan H.,
Richey Jeffrey E.,
Martinelli Luiz A.,
dos Santos Humberto
Publication year - 1988
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1988.33.1.0041
Subject(s) - nutrient , floodplain , environmental science , hydrology (agriculture) , drainage basin , phosphorus , water quality , hydrobiology , chlorophyll a , surface runoff , sedimentation , water column , environmental chemistry , sediment , ecology , chemistry , biology , geology , geography , paleontology , biochemistry , geotechnical engineering , cartography , organic chemistry , aquatic environment
Nutrient chemistry in lakes of the central floodplain of the Amazon River is influenced by the relative mix of waters of river and local origin. At high water the lakes contained primarily river water, lake and river total nitrogen (TN) levels were similar, concentrations of total suspended solids (TSS), soluble reactive phosphorus (SRP), dissolved inorganic nitrogen (DIN), and total phosphorus (TP) in the lakes were significantly lower than those in the river, and chlorophyll a (Chl a ), transparency, and TN : TP levels were higher. The apparent decline in TP in the lakes was correlated with river TSS, suggesting a sedimentation loss. The higher TN : TP in the lakes reflected the differential loss of TP. At low water the percentage of local water in most lakes increased. The relative magnitude of this increase and its effect on nutrient chemistry depended on the ratio of drainage basin area to lake area (BA: LA). Lakes with BA: LA ≲20 contained a mixture of river and local water by the end of the low water period with a variable nutrient composition; lakes with BA: LA 20 contained primarily local water with a nutrient composition similar to that of forest runoff. Concentrations of TP in the lakes were near the levels expected from conservative mixing, suggesting a partial recovery of TP lost during high water. Levels of TN and TN : TP were higher than those expected from conservative mixing, suggesting an additional source of N.