North Temperate Lakes LTER: Color - Trout Lake Area 1989 - current

Color is measured four times a year in the seven northern study lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes, unnamed lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog]) in water samples that are filtered in the field through 0.45 um nucleopore membrane filters. A spectrophotometer is used to quantify color in the lab as absorbance (unitless) at 1 nm intervals between the wavelengths of 200 and 800 nm (Note: Prior to August 2008, samples were initially run in 10cm cuvettes. Starting in Aug 2008, samples are initially run in 5cm cuvettes. Absorbance data are considered suspect for values greater than 2. Lakes with suspect data (typically, the bog lakes) are re-analyzed in the 200-400 nm range in 1 cm cuvettes. The data values are linear with respect to cuvette size. I.e, data from the 1cm cuvettes should be multiplied by 5 to be comparable with 5cm cuvette data and multiplied by 10 to be comparable with 10cm cuvette data. Data from 5cm cuvettes should be multiplied by 2 to be comparable with the older 10cm cuvette data. Sampling Frequency: 4 times annually Number of sites: 7

本数据集针对北部7个研究湖泊——包括Allequash湖、Big Muskellunge湖、Crystal湖、Sparkling湖、Trout湖，以及未命名湖泊27-02（Crystal Bog）和12-15（Trout Bog）——的水体样本，每年开展4次色度测定。样本在野外通过0.45 μm核孔微孔滤膜（nucleopore membrane filters）完成过滤。实验室采用分光光度计，在200~800 nm波长范围内以1 nm为间隔测定吸光度（无单位）以定量水体色度。注：2008年8月前，样本初始测试采用10 cm比色皿；自2008年8月起，初始测试改用5 cm比色皿。吸光度大于2的数值被视为可疑数据。存在可疑数据的湖泊（通常为泥炭湖）会使用1 cm比色皿，在200~400 nm范围内重新分析。数据值与比色皿尺寸呈线性相关：1 cm比色皿的测定数据需乘以5，方可与5 cm比色皿的数据等效；乘以10则可与10 cm比色皿的数据等效。5 cm比色皿的测定数据需乘以2，方可与早期10 cm比色皿的测定数据等效。采样频率：每年4次；采样点位数量：7个