Eawag, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland.
Environ Sci Technol. 2012 Sep 18;46(18):9964-71. doi: 10.1021/es301422r. Epub 2012 Aug 24.
The oxygen-consuming processes in the hypolimnia of freshwater lakes leading to deep-water anoxia are still not well understood, thereby constraining suitable management concepts. This study presents data obtained from 11 eutrophic lakes and suggests a model describing the consumption of dissolved oxygen (O(2)) in the hypolimnia of eutrophic lakes as a result of only two fundamental processes: O(2) is consumed (i) by settled organic material at the sediment surface and (ii) by reduced substances diffusing from the sediment. Apart from a lake's productivity, its benthic O(2) consumption depends on the O(2) concentration in the water overlying the sediment and the molecular O(2) diffusion to the sediment. On the basis of observational evidence of long-term monitoring data from 11 eutrophic lakes, we found that the areal hypolimnetic mineralization rate ranging from 0.47 to 1.31 g of O(2) m(-2) d(-1) (average 0.90 ± 0.30) is a function of (i) a benthic flux of reduced substances (0.37 ± 0.12 g of O(2) m(-2) d(-1)) and (ii) an O(2) consumption which linearly increases with the mean hypolimnion thickness (z(H)) up to ~25 m. This model has important implications for predicting and interpreting the response of lakes and reservoirs to restoration measures.
淡水湖泊底层的耗氧过程导致深水缺氧，但目前对此仍了解不足，这限制了合适的管理概念的提出。本研究提供了来自 11 个富营养化湖泊的数据，并提出了一个模型，描述了富营养化湖泊底层溶解氧（O(2)）的消耗仅由两个基本过程引起：（i）沉降在沉积物表面的有机物质消耗 O(2)，以及（ii）从沉积物中扩散的还原物质消耗 O(2。除了湖泊的生产力之外，其底栖 O(2)消耗还取决于覆盖沉积物的水层中的 O(2)浓度和分子 O(2)向沉积物的扩散。基于对 11 个富营养化湖泊的长期监测数据的观测证据，我们发现，从 0.47 到 1.31 g 的 O(2) m(-2) d(-1)（平均值为 0.90 ± 0.30）的面积性底层矿化速率是（i）还原物质的底栖通量（0.37 ± 0.12 g 的 O(2) m(-2) d(-1))和（ii）与平均底层厚度（z(H))呈线性关系的 O(2)消耗的函数，直至约 25 m。该模型对预测和解释湖泊和水库对恢复措施的响应具有重要意义。
