Collection and sample processing methods: Lake water samples are collected at specific depths with a five-liter Niskin bottle during routine LTER limnological sampling. Sub-samples for DOC analysis are decanted into a 1 L amber Nalgene bottle. One-100 mL sub-sample is taken from the one-liter amber Nalgene bottle. The sub-sample is filtered through a combusted (475 degrees celsius for 4 hours) Whatman 25 mm GF/F and collected directly into a 100 mL acid washed, combusted amber borosilicate glass bottle (475 degrees Celsius for 4 hours), preserved with 1 mL of 6N hydrochloric acid (HCL), and capped with a Teflon-lined screw cap. The sample is stored at 4 deg. Celsius until analysis with the Shimadzu 5000 TOC analyzer (before the 0203 season), or the Shimadzu TOC-V (current). The filter is used for chlorophyll-a analysis.
To reduce salt interference, samples are diluted as follows in this link https://mcm.lternet.edu/sites/default/files/DilutionsTable%200001-1617.xlsx
Method detection limits (MDL) are as follows:
Instrument output that could not be quantified are denoted as ND.