Controls on biochemical oxygen demand in the upper Klamath River,Oregon |
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| Authors: | Annett B. Sullivan Dean M. Snyder Stewart A. Rounds |
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| Affiliation: | 1. U.S. Geological Survey, 2130 SW 5th Avenue, Portland, OR 97201, USA;2. U.S. Geological Survey, 2795 Anderson Avenue, Suite 106, Klamath Falls, OR 97603, USA;1. Department of Civil Engineering, G D Goenka University, Gurugram, Haryana 122103, India;2. Department of Civil Engineering, Indian Institute of Technology, Delhi (IITD), New Delhi 110016, India;1. Department of Industrial Engineering, Sharif University of Technology, Tehran 14588-89694, Iran;2. Department of Pure & Applied Mathematics, Yazd University, Yazd 89195-741, Iran;1. Department of Water Science & Engineering, College of Agriculture, Vali-e-Asr University of Rafsanjan, P.O. Box 518, Rafsanjan, Iran;2. Department of Technical and Engineering, Faculty of Civil Engineering, Vali-e-Asr University of Rafsanjan, P.O. Box 518, Rafsanjan, Iran;3. Department of Biological and Agricultural Engineering and Zachry Department of Civil Engineering, Texas A&M University, 2117 TAMU, College Station, TX 77843-2117, USA;1. National Institute of Hydrology, Roorkee-247667, Uttarakhand India;2. Doon University, Dehradun, Uttarakhand, India |
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| Abstract: | A series of 30-day biochemical oxygen demand (BOD) experiments were conducted on water column samples from a reach of the upper Klamath River that experiences hypoxia and anoxia in summer. Samples were incubated with added nitrification inhibitor to measure carbonaceous BOD (CBOD), untreated to measure total BOD, which included demand from nitrogenous BOD (NBOD), and coarse-filtered to examine the effect of removing large particulate matter. All BOD data were fit well with a two-group model, so named because it considered contributions from both labile and refractory pools of carbon: BODt = a1(1 ? e? a0t) + a2t. Site-average labile first-order decay rates a0 ranged from 0.15 to 0.22/day for CBOD and 0.11 to 0.29/day for BOD. Site-average values of refractory zero-order decay rates a2 ranged from 0.13 to 0.25 mg/L/day for CBOD and 0.01 to 0.45 mg/L/day for BOD; the zero-order CBOD decay rate increased from early- to mid-summer. Values of ultimate CBOD for the labile component a1 ranged from 5.5 to 28.8 mg/L for CBOD, and 7.6 to 30.8 mg/L for BOD. Two upstream sites had higher CBOD compared to those downstream. Maximum measured total BOD5 and BOD30 during the study were 26.5 and 55.4 mg/L; minimums were 4.2 and 13.6 mg/L. For most samples, the oxygen demand from the three components considered here were: labile CBOD > NBOD > refractory CBOD, though the relative importance of refractory CBOD to oxygen demand increased over time. Coarse-filtering reduced CBOD for samples with high particulate carbon and high biovolumes of Aphanizomenon flos-aquae. There was a strong positive correlation between BOD, CBOD, and the labile component of CBOD to particulate C and N, with weaker positive correlation to field pH, field dissolved oxygen, and total N. The refractory component of CBOD was not correlated to particulate matter, instead showing weak but statistically significant correlation to dissolved organic carbon, UV absorbance at 254 nm, and total N. Particulate organic matter, especially the alga A.flos-aquae, is an important component of oxygen demand in this reach of the Klamath River, though refractory dissolved organic matter would continue to exert an oxygen demand over longer time periods and as water travels downstream. |
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