North Temperate Lakes LTER: Chlorophyll - Madison Lakes Area 1995 - current

Chlorophyll is measured at our permanent sampling station in the deepest part of the lake. Chlorophyll samples are collected from the four primary study lakes in the Madison area (Lakes Mendota, Monona, and Wingra and Fish Lake) at integrated depths and discrete depths for spectrophotometric analysis and fluorometric analysis. Due to a change in instruments starting in 2002 and lasting through 2007, chlorophyll analyses for the southern lakes had an uncorrectable bias, and are not included in this dataset.  Analyses since then (2008 onward) have been determined to not have this bias. Sampling Frequency: bi-weekly during ice-free season from late March or early April through early September, then every 4 weeks through late November; sampling is conducted usually once during the winter (depending on ice conditions). Number of sites: 4

本研究在湖泊最深区域的固定采样站点开展叶绿素含量测定工作。研究采样覆盖麦迪逊地区四座主要研究湖泊：门多塔湖（Lake Mendota）、莫诺纳湖（Lake Monona）、温格拉湖（Lake Wingra）与菲什湖（Fish Lake），分别通过整合采样深度（integrated depths）与离散采样深度（discrete depths）采集叶绿素样品，用于分光光度分析（spectrophotometric analysis）与荧光光度分析（fluorometric analysis）。由于2002年至2007年间仪器设备更新，南部湖泊的叶绿素分析结果存在无法校正的系统偏差，相关数据未纳入本数据集；2008年及之后的分析结果经确认无此类偏差。采样频率如下：无冰期（3月末至4月初至9月初）每两周采样一次，9月初至11月末每四周采样一次；冬季通常采样一次（具体依冰情调整）。采样点位总数为4个。