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Stable carbon isotope ratios of tree-ring cellulose from oak (Quercus robur) at Lake Tiefer See, Mecklenburg Lake District, Northeastern Germany

Methods

Concentrations of selected elements and organochlorine pesticides in layers of dated sediment cores of ten lakes in northeastern Germany

Lake sediment chronologies of ten lakes in northeastern Germany (Arendsee [AS], Carwitzer See [CR], Feldberger Haussee [FH], Breiter Luzin [BL], Schmaler Luzin [SL], Oberuckersee [OR], Scharmützelsee [PL], Stechlinsee [ST], Tiefwarensee [TF], Großer Wummsee [WM]) were created to reconstruct anthropogenic activity over the past 100 years starting from 2015 as the most present date. Collection of samples took place between 2015-07-10 and 2015-09-04 for all but one lake which was re-sampled in December 2016 (ST). Cores of lake sediments were collected using a gravity corer (90 mm diameter; UWITEC, Mondsee, Austria). Minimum length of the cores was 1 m. Cores were sliced immediately at the shore of each lake into 5 mm (lakes FH and BL) or 10 mm samples (all other lakes). Sliced cores were stored at 4 °C until arrival at the IGB laboratory at Lake Stechlin. There, they were weighed and then frozen at -20 °C for storage until further processing. Loss of ignition was determined using an electric muffle furnace (SNOL 8,2/1100, Utena, Lithuania). Dating of each sliced core horizon was performed by direct gamma assay of isotopes 210Pb and 137Cs of a freeze-dried subsample (1 g). Depending on the lake, a time span starting with the sampling year (i.e. 2015/2016) and reaching back to at least the 1950s and at most to pre-1900s was covered. Concentrations of elements (aluminium, arsenic, calcium, cadmium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, molybdenum, sodium, nickel, phosphorus, lead, sulphur, zinc) were determined with microwave-assisted aqua-regia (MAE-AR) extraction in conjunction with inductively coupled plasma-optical emission spectrometry (ICP-OES). Concentrations of organic pesticides DDX (2,4'- and 4,4'- congeners of each dichlorodiphenyltrichloroethane [DDT], dichlorodiphenyldichloroethane [DDD] and dichlorodiphenyldichloroethylene [DDE]), hexachlorobenzene (HCB), HCHs (α-, β-, γ-, δ-hexachlorocyclohexane [HCH]) and trifluralin were extracted applying miniaturized solid-liquid extraction (MISOLEX; Simon et al. 2021, doi:10.1007/s11368-021-03080-0). Extracts were measured with solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS).

Stable oxygen isotope ratios of tree-ring cellulose from oak (Quercus robur) at Lake Tiefer See, Mecklenburg Lake District, Northeastern Germany

Methods

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