| Title |
Evaluation of Autochthonous BOD caused by Production of Algae at Different Spatial and Temporal Scales in the Eutrophic Nakdong River |
| Authors |
(Sung Kyo Shin) ; (Kyo Ook Song) ; (Chung Kil Park) |
| Abstract |
The relationships between of the organic constituents were investigated at laboratory scale and by field study to determine the autochthonous BOD resulting from algal production in the eutrophic Nakdong River, Korea. From the results of growth and degradation of algae in laboratory, the ratio of particulate biochemical oxygen demand (PBOD) to particulate organic matter (POM) was 0.349 during culture and 0.213 during degradation, and it was 28.1% and 17.1% of theoretical oxidation ratio (1.244), respectively. This means that the consumption of dissolved oxygen (DO) was caused by algal respiration and detrital degradation during culture, but only by detrital degradation during degradation. From the relationship between chl-a and BOD (Total BOD (TBOD) = autochthonous BOD ( α·chl-a) + allochthonous BOD), we could determine the contribution of autochthonous BOD to total BOD. Autochthonous BOD ranged from 31.7 to 52.5% in the river reach and from 36.2 to 56.9% in each season. To apply a conversion factor for the calculation of autochthonous BOD, the algal biomass produced should be considered, as well as the activity of the algae, which changed with temporal and spatial conditions. From these results, the autochthonous BOD determined in the Nakdong River accounted for the majority of total BOD in the overall reach investigated. |