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ALGAL PRODUCTIVITY AND NITRATE ASSIMILATION IN AN EFFLUENT DOMINATED CONCRETE LINED STREAM 1
Author(s) -
Kent Robert,
Belitz Kenneth,
Burton Carmen A.
Publication year - 2005
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/j.1752-1688.2005.tb03788.x
Subject(s) - nitrate , diel vertical migration , effluent , productivity , nitrogen assimilation , environmental science , hydrology (agriculture) , environmental chemistry , chemistry , ecology , environmental engineering , biology , geology , geotechnical engineering , economics , macroeconomics
This study examined algal productivity and nitrate assimilation in a 2.85 km reach of Cucamonga Creek, California, a concrete lined channel receiving treated municipal wastewater. Stream nitrate concentrations observed at two stations indicated nearly continuous loss throughout the diel study. Nitrate loss in the reach was approximately 11 mg/L/d or 1.0 g/m 2 /d as N, most of which occurred during daylight. The peak rate of nitrate loss (1.13 mg/l/hr) occurred just prior to an afternoon total CO 2 depletion. Gross primary productivity, as estimated by a model using the observed differences in dissolved oxygen between the two stations, was 228 mg/L/d, or 21 g/m 2 /d as O 2 . The observed diel variations in productivity, nitrate loss, pH, dissolved oxygen, and CO 2 indicate that nitrate loss was primarily due to algal assimilation. The observed levels of productivity and nitrate assimilation were exceptionally high on a mass per volume basis compared to studies on other streams; these rates occurred because of the shallow stream depth. This study suggests that concrete‐lined channels can provide an important environmental service: lowering of nitrate concentrations similar to rates observed in biological treatment systems.