Microbial Planktonic Respiration in Lakes at North Temperate Lakes LTER 2001

Respiration of total plankton passing a 70 micron mesh, and bacteria passing a 1 micron
mesh, calculated from loss of oxygen in lake water incubated at in situ temperatures. Oxygen
concentration was determined using the Winkler reaction with azide modification. Final
product concentration determined via spectrometry or titration with sodium thiosulfate.
Titrations that may have overrun the endpoint were not included. The following equation for
calculation of dissolved oxygen concentration from titration of Winkler end product with
thiosulfate (from Wetzel, R. G. and G. E. Likens. 1991. Limnological Analyses, 2nd ed.
Springer-Verlag, New York). Thiosulfate with a molarity of 0.20 N was used for all
titrations. mg O2 L-1 = (ml titrant)*(molarity of thiosulfate)*(8000)/((ml of sample
titrated)*((ml of bottle -3)/(ml of bottle))). The following equation is for calculation of
dissolved oxygen calculation from spectophotometric analysis of Winkler reaction end product
(from Roland, F., N. F. Caraco, J. J. Cole. 1999. Rapid and precise determination of
dissolved organic oxygen by spectrophotometry: Evaluation of interference from color and
turbidity. Limnol. Oceanogr. 44(4):1148-1154). mg O2 L-1 = absorbance at 430 nm (in units of
cm-1) * 8.1-0.41 Sampling Frequency: fortnightly during ice-free season - every 6 weeks
during ice-covered season Number of sites: 4

本数据集测定通过70微米筛网的全部浮游生物，以及通过1微米筛网的细菌的呼吸耗氧速率，该速率通过原位温度下培养的湖水的氧消耗量计算得到。氧浓度采用叠氮化钠修正的温克勒（Winkler）反应法测定，反应终产物浓度通过分光光度法或硫代硫酸钠滴定法确定。滴定超出终点的样本未纳入统计。

以下为利用硫代硫酸钠滴定温克勒反应终产物以计算溶解氧浓度的公式（来源：Wetzel, R. G. 与 G. E. Likens，1991年，《湖沼学分析（第2版）》，施普林格出版社，纽约）：所有滴定实验均使用浓度为0.20当量浓度（N）的硫代硫酸钠溶液。
溶解氧浓度（mg O₂·L⁻¹）=（滴定剂体积，mL）×（硫代硫酸钠摩尔浓度）×8000 /（滴定样本体积，mL ×（培养瓶体积 - 3）/培养瓶体积）

以下为通过分光光度法分析温克勒反应终产物以计算溶解氧浓度的公式（来源：Roland, F.、N. F. Caraco与J. J. Cole，1999年，《通过分光光度法快速精准测定溶解有机氧：色度与浊度的干扰评估》，《湖沼学与海洋学》，44(4):1148-1154）：
溶解氧浓度（mg O₂·L⁻¹）= 430 nm处吸光度（单位：cm⁻¹）×8.1 - 0.41

采样频率：无冰期每两周采样一次，冰盖期每六周采样一次。
采样点位数量：4个。