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Organic matter composition (isotopic composition and biomarker characterisation) from Lake Paringa and soils from Westland, New Zealand (NERC Grant NE/P013538/1)
The dataset contains geochemical measurements which quantify the amount and source of carbon in organic matter of sediments from Lake Paringa, New Zealand. Measurements were made on a 6 m sediment core collected in 2015 from the lake bed using a Mackereth corer (PA6m1a). The core was correlated to master core PA1 which has a well-established age-depth model based on accelerator mass spectrometry measurements of the radiocarbon (14C) content of terrestrial macrofossils (Howarth et al., 2016). In addition, soil samples were collected using a soil auger from two elevation transects in westland, New Zealand in 2016 and 2017 (from Mt. Fox and Alex Knob). All sediment samples were freeze dried and ground to homogenise them prior to geochemical analyses. Organic carbon concentration (%) and the stable isotopic composition of organic carbon (δ13C) was measured (Frith et al., 2018) following the removal of carbonate minerals (0.25 M hydrochloric acid for 4 hours at approximately 70 °C) by combustion of sediment at 1,020 °C in a Costech Elemental Analyser coupled via a CONFLO III to a Thermo Scientific Delta V Advantage stable isotope mass spectrometer. Total nitrogen content (N, %) and its isotopic composition (δ15N) was measured by combustion of untreated samples in a Costech Elemental Analyser with a CARBOSORB trap to inhibit large CO2 peaks from affecting measurements. A subset of samples were selected for analysis of the radiocarbon activity (14C, reported as F14C) of bulk organic matter by accelerator mass spectrometry after graphitization. A subset of sediment samples from the lake core and soil samples were selected for the analysis of biomarker abundance and their hydrogen isotope composition. We focused on the extraction of n-alkanes from aliquots of lake sediment (~2 g) using established methods (Wang et al., 2020). These measurements are reported in the dataset as the abundance of n-alkanes (chain lengths C21 to C35) in ug/g of sediment (and sum of chain lengths and ratios - carbon preference index). Finally, the dataset includes outputs of organic matter provenance: modelled elevation and depth, as described in Wang et al., (2020). In the datafile, the sample elevation and depth are provided. The labels for data are as follows. For down core sediment samples from Lake Paringa, they are labelled with the core code (PA6m1), and the sampling interval in centimetres (PA6m1_x). Soil samples from an elevation transect from Mt Fox (MF-YY-a) are labelled with a distinct code for each site (YY) and sub-code for each soil depth (a). Soil samples from an elevation transect of Alex Knob (5.Z.z) are labelled based on sub-site (Z) and soil depth (z).
Noble gas and clumped methane data for samples from Anyue gas field, China (NERC Grant NE/T004452/1)
This dataset contains 6 tables covering all analytical data for samples collected from the Anyue gas field, central Sichuan Basin, China. Table 1 includes major gas species and stable carbon and hydrogen isotopes. Table 2 includes results for methane clumped isotopes and calculated methane formation temperatures of gas samples. Table 3 includes noble gas concentrations. Table 4 includes noble gas isotopic ratios. Table 5 includes parameters used in methane emission model and calculating total volume of methane emission. Table 6 includes gas composition and stable carbon and hydrogen isotope characteristics of major gases produced in the pyrolysis experiments (thermally equilibrated methane between 400~500 in theory) and working reference gas, and their methane clumped isotope values.
Water isotope data from Yaal Chac (lake), nearby groundwater and local precipitation (NERC grant NE/K00610X/1)
Surface waters and shallow groundwater samples were collected by completely filling 30 mL polyethylene bottles, which were then sealed with electrical tape to minimise the risk of evaporative loss. Rainwater samples were integrated samples of total monthly rainfall collected in a specially-adapted rainfall collector following IAEA protocols (IAEA http://www-naweb.iaea.org/napc/ih/documents/userupdate/sampling.pdf [accessed 22 June 2012). Mexico, State of Yucatan. Yaal Chac (lake) (lake centre is Lat: 20.595274 degrees; Long: -89.711301 degrees), Abala Well (Lat: 20.649044 degrees; Long: -89.679814 degrees) and Xanil ha Cave (Lat: 20.650809 degrees; Long: -89.697426 degrees) Rainwater sampler was located adjacent to the lake. Refer to accompanying map for the precise location of the sampling sites.