Lake water quality, chemistry and zooplankton composition for 16 lakes surrounding the Green Lakes Valley, 2016

This dataset contains water chemistry measurements made from 16
different lakes north and south of LTER site in the green lakes
valley. At each visit water samples were collected for analysis of
chlorophyll a and nutrient analysis and field measurements were
recorded for pH, temperature, specific conductivity, dissolved oxygen
(DO), % saturation, secchi depth, PAR.  Secchi depth was measured
using a 30cm disk to the nearest 0.25 meter and here recorded at the
0m row in the data file however it is a measurement of depth and so
the units are meters. Most samples were collected between 0900 and
1300 MST. The first sampling date occurred shortly after lake had
become ice free and then if the lake was at least 3 meters deep it was
re-surveyed at approximately 2 week intervals. All data are collected
from an inflatable raft at the point of deepest depth. All water
samples were taken at the surface (0m), and the hypolimnion (about 2m
above the lake sediment) using a Van Dorne sampler. Chlorophyll-a was
extracted from water sample filters and absorbance was measured before
and after acidification to quantify chlorophyll a concentration. Field
measurements were conducted using a YSI either DO or multiple probe
meter (YSI MPS 556) and a Li-Cor meter with a quantum sensor.
Zooplankton samples were collected opportunistically 3 times
throughout the summer, once immediately after ice-out and two more
times with at least 14 days bewteen each subsequent visit. Zooplankton
were sampled at the deepest location of each lake by pulling a conical
net (Wisconsin net) vertically through the water column (i.e.,
vertical tow sample). The Wisconsin net is 0.9m long with an opening
of an inner diameter of 0.2m and a mesh size of 80um. The vertical tow
samples are taken from approximately 0.5 m off the lake bottom. After
the net is raised and the sides rinsed, the sample is transferred to
a 250 mL jar and preserved in a solution of 80% Ethanol. Jars are
labeled with date (yyyy-mm-dd), time hh:mm (MST), lake, depth and net
details and stored at room temperature until analysis.

本数据集涵盖了绿湖谷（Green Lakes Valley）内长期生态研究（LTER）站点南北两侧16个不同湖泊的水质理化测量数据。每次采样均采集水样用于叶绿素a及营养盐分析，并现场记录pH值、水温、比电导率、溶解氧（DO）、饱和度百分比、塞氏盘深度（Secchi depth）及光合有效辐射（PAR）。塞氏盘深度采用直径30cm的圆盘进行测量，精度至0.25米；尽管数据文件中将其记录于0m行，但该指标实际为深度参数，单位为米。绝大多数水样采集于山地标准时间（MST）09:00至13:00之间。首次采样于湖泊解冻后不久开展；若湖泊水深不小于3米，则每约2周进行一次复测。所有数据均于各湖泊的最深点，通过充气筏采集获得。所有水样均采用范多恩采水器（Van Dorne sampler）采集，采样层包括表层（0m）及湖下层（距湖底沉积物约2米处）。叶绿素a通过水样过滤膜提取，通过酸化前后的吸光度测量值定量其浓度。现场测量采用YSI溶解氧单参数或多参数水质分析仪（YSI MPS 556），以及搭载量子传感器的LI-COR辐射计。本数据集还包含浮游动物（Zooplankton）样本：夏季共采集3次，首次采样于湖泊解冻后即刻开展，后续两次采样的间隔均不少于14天，采样时机随现场条件灵活调整。浮游动物样本采集于各湖泊的最深点，采用锥形网（威斯康星网，Wisconsin net）进行垂直拖网采样（即垂直拖网样本）。该威斯康星网全长0.9米，网口内径0.2米，网孔尺寸为80微米。垂直拖网采样的起始深度为距湖底约0.5米处。拖网提升并冲洗网身后，将样本转移至250mL广口瓶中，采用80%乙醇溶液进行保存。广口瓶的标签标注内容包括采样日期（格式为yyyy-mm-dd）、采样时间（hh:mm，山地标准时间）、湖泊名称、采样深度及网具相关信息，样本在室温下储存直至开展实验室分析。