Juhls, Bennet; Overduin, Pier Paul; Morgenstern, Anne; Lütjen, Martha; Esterl, Pia; Walther, Henrike; Bochow, Mathias: Colored dissolved organic matter of Lena River water from 13.09.2019 (#202) to 23.08.2021 (#487) [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.967406 (dataset in review),

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In: Juhls, Bennet; Morgenstern, Anne; Chetverova, Antonina; Eulenburg, Antje; Hölemann, Jens A; Povazhnyi, Vasily; Overduin, Pier Paul (2020): Lena River surface water monitoring near the Samoylov Island Research Station [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.913197

We collected water samples from the river surface in the center of the Olenekskaya Channel near Samoylov Island using a pre-rinsed HDPE 1 L bottle. During the open water period (June to October), water was sampled from a small boat, and during ice-covered period (November to May), through a hole drilled through the river ice. Some samples during the river ice break-up (between May and June) as well as some samples during the ice freeze-up in October were taken from the shore due to the inaccessibility of a more centered location on the river channel. For CDOM absorption (aCDOM(λ)), the sample was filtered through a 0.45 μm cellulose acetate filter which had been rinsed with 20 mL sample water. CDOM samples were collected in pre-rinsed 50 or 100 mL amber glass bottles that were stored in the dark at 4°C until analysis. aCDOM was measuredat the German Research Center for Geosciences (GFZ), Potsdam, Germany using a double beam LAMBDA 950 UV/Vis (PerkinElmer) spectrophotometer. The absorbance (A) was measured between 200 and 800 nm in 1 nm steps using a 1, 2 or 5 cm cuvette, depending on the expected concentration of dissolved organic matter. Absorption (a) was calculated from the resulting absorbance measurements via aCDOM(λ) = 2.303 * A(λ) * l, where l is the path length (length of cuvette in meter). Every 5 to 10 samples, the reference sample (Milli-Q water) was exchanged and a blank was measured to avoid instrument drift.