Lake Metabolism: Comparison of Lake Metabolic Rates Estimated from a Diel CO2- and the Common Diel O2-Technique
Lake Metabolism: Comparison of Lake Metabolic Rates Estimated from a Diel CO2- and the Common Diel O2-Technique
复制标题
湖泊代谢：通过 Diel CO2 技术和普通 Diel O2 技术估算的湖泊代谢率的比较
作者：
Frank Peeters;D. Atamanchuk;Anders Tengberg;Jorge Encinas;H. Hofmann
湖泊代谢是了解湖泊生态系统中能量以及有机物和无机物周转的关键因素。代谢率的长期时间序列通常根据溶解氧的昼夜变化来估计。在这里，我们利用开放水域昼夜二氧化碳技术，提供基于总溶解无机碳 (DIC) 昼夜变化的代谢率的长期数据。尽管 CO2 摩尔浓度的昼夜变化远小于 O2 摩尔浓度的昼夜变化，但在碱性伊尔门湖（pH 约为 8.5）中，用该技术估计的代谢率与传统的昼夜 O2 技术非常吻合。开放水域昼夜二氧化碳和昼夜氧气技术提供了湖泊代谢率的独立测量，其对运输过程的敏感性不同。因此，两种技术的结合可以帮助限制由于气体交换和湍流扩散而引起的垂直通量假设所产生的不确定性。这对于湖泊呼吸速率的估计尤其重要，因为与湖泊总初级生产的估计相比，这些对 O2 或 DIC 垂直通量梯度的假设更加敏感。我们的数据表明，假设垂直通量的梯度可以忽略不计，而不是包括与大气的气体交换但忽略水柱中的垂直混合，估计呼吸速率可能是有利的。在夏季的两个月里，湖泊的平均净产量接近于零，这表明最多存在轻微的自养条件。然而，湖泊在整个时间段内都排放着氧气和二氧化碳，这表明湖泊的氧气和二氧化碳排放可以与近地表层的新陈代谢脱钩。
Lake metabolism is a key factor for the understanding of turnover of energy and of organic and inorganic matter in lake ecosystems. Long-term time series on metabolic rates are commonly estimated from diel changes in dissolved oxygen. Here we present long-term data on metabolic rates based on diel changes in total dissolved inorganic carbon (DIC) utilizing an open-water diel CO2-technique. Metabolic rates estimated with this technique and the traditional diel O2-technique agree well in alkaline Lake Illmensee (pH of ~8.5), although the diel changes in molar CO2 concentrations are much smaller than those of the molar O2 concentrations. The open-water diel CO2- and diel O2-techniques provide independent measures of lake metabolic rates that differ in their sensitivity to transport processes. Hence, the combination of both techniques can help to constrain uncertainties arising from assumptions on vertical fluxes due to gas exchange and turbulent diffusion. This is particularly important for estimates of lake respiration rates because these are much more sensitive to assumptions on gradients in vertical fluxes of O2 or DIC than estimates of lake gross primary production. Our data suggest that it can be advantageous to estimate respiration rates assuming negligible gradients in vertical fluxes rather than including gas exchange with the atmosphere but neglecting vertical mixing in the water column. During two months in summer the average lake net production was close to zero suggesting at most slightly autotrophic conditions. However, the lake emitted O2 and CO2 during the entire time period suggesting that O2 and CO2 emissions from lakes can be decoupled from the metabolism in the near surface layer.
影响因子：
3.7
作者：
Hofmann H;Peeters F
通讯作者：
Peeters F