This data set contains chemical and Mg isotope analyses of time-series creek water, subsurface flow (0-15cm and 15-150cm), vegetation, regolith, clay-sized fraction and exchangeable fraction of regolith from a catchment of the Black Forest, Germany. This dataset is a following work of “Uhlig, D., & von Blanckenburg, F. (2019)", in which major and trace elements concentrations and 87Sr/86Sr isotope data was reported on the same batch of samples. With the new Mg isotope analyses, we investigated the potential controlling factors on water Mg isotopic composition, and we found exchange reactions in our catchment are a primary control on water chemistry. To further interrogate this finding, a batch of adsorption and desorption experiments using soil samples from our study site were carried out. The adsorption and desorption experiment results are also included here. This combination of field research and lab experiments informs about processes fractionating Mg in the critical zone – with the role of the exchangeable pool highlighted as particularly important – and further verifies the potential of Mg isotopes as a tool in tracing continental weathering process. Samples are assigned with International Geo Sample Numbers (IGSN), a globally unique and persistent Identifier for physical samples.
The data set consists of magnesium (Mg), oxygen (O), and hydrogen (H) isotope signatures and Mg concentrations of monthly collected precipitation and daily snow samples. Samples were collected between December 2014 and June 2017 in the village of Gevelsberg (NW Germany, 51.32°N, 7.32°E) at 206 m above sea level. Rainwater was collected daily using a funnel connected to a 5 liter PET canister. The collected water was transferred into a second canister to store the monthly sample. Snow samples were separately collected on the days of snowfall in ca. 5 m distance to the rainwater collection site using 500 ml PET bottles. The full snow thickness was sampled using a small scoop. All collected monthly and daily snow samples were filtered using 0.45µm cellulose-acetate filters (Sartorius) and stored in a fridge. Subsequent analysis of rain and snow samples include Mg concentration analysis using an ICP-OES (iCAP 6500 DUO, Thermo Fisher Scientific) and Magnesium isotope composition analysis using an MC-ICP-MS Neptune (Thermo Fisher Scientific) at the Ruhr-University Bochum, Germany. Oxygen and hydrogen isotope composition was determined using cavity ring-down spectrometry (L2140i, Picarro) at Innsbruck University, Austria.
The dataset contains chemical analyses from the well-characterised Hakgala field site in the tropical Highlands of Sri Lanka. This site is located on a road cut between Nuwara Elia and Welimada (06.92923° N, 80.81834° E, 1753 m altitude), bordering a 12 km^2 natural forest reserve consisting of pristine, mature, stable upper montane rain forest, close to the Hakgala Botanical Garden. A deeply weathered regolith depth profile (ca. 10 m) developed on a hillslope underlain by charnockite bedrock. Adjacent to the regolith profile ecologically pristine catchments (>1 km^2) are drained by small creeks.Here, data on samples of all compartments of the Critical Zone (defined as the near surface layer of the Earth extending from the bottom of the weathering zone to the top of the tree canopy) are reported. The dataset compiles published (Hewawasam et al., 2013, GCA, 118, 202-230) and new data (Schuessler et al., 2018, Chemical Geology) of element concentrations, stable Mg isotopes, and radiogenic Sr isotope ratios on stream water (time series sampling 2010-2013), vegetation, soil, saprolite (depth profile sampling), weathered bedrock (corestones), and unweathered bedrock. From this data, weathering indicators such as the chemical depletion fraction (CDF) and the element mass transfer coefficients (Tau) were calculated and reported in the dataset.The samples used for these analyses have been assigned with International Geo Sample Numbers (IGSN, www.igsn.org). Details on sampling locations are provided via IGSN links in the tables and in the related work section on the DOI Landing Page at GFZ Data Services. Moreover, the IGSN data can be accessed by adding the IGSN after igsn.org, e.g. igsn.org/GFFB1003V. Further details on sampling and locations are provided in Hewawasam et al. (2013, GCA, 118, 202-230).This publication contains an annotated summary table serving as a supplementary table for Schuessler et al. (2018, Chemical Geology) in pdf and xlsx (Microsoft Excel) formats. In addition, separate tables reflecting differing samples and methodologies for input into statistical software are provided as comma separated files. Column headers for all tables are explained in a separate csv file (Data columns headers for tables S1 to S3.csv). The analytical methodologies used to generate the data are described in the data description file.