The bioavailability and chemical composition of the organic component of soils and sediments from the catchment to reef (NESP TWQ 5.8, Griffith University)

This data set provides detailed information about the chemical composition, bioavailability and relative abundance of organic compounds in plant material and the organic associated with soil and sediment samples collected from terrestrial and marine environment of the Great Barrier Reef.

*This dataset is currently under embargo.

Methods:
Pre-treatment of soil and sediment samples with HF before solid-state 13C CPMAS NMR analysis removes substantial amounts of Fe2+ and Mn2+ in soil and sediment and concentrates the organic matter content of the whole sample, improving the signal/noise ratio. In this study, all soil and sediment samples for NMR analysis were pre-treated with HF 5%. Solid-state 13C CPMAS NMR spectra of the HF treated samples were obtained at a frequency of 100.6 MHz on a 300 MHz Varian VNMRS spectrometer (Varian Inc.,CA). Samples were packed in a silicon nitride rotor (optical density=7mm) and spun at 5 kHz at the magic angle. Single contact times of 2 ms were applied, with an acquisition time of 14 ms, and a recycle delay of 1.5 s. Approximately 20,000 transients were collected for all soil and sediment samples and 2,000 transients were collected for plant litter. Lorentzian line broadening function of 150 Hz was applied to all spectra. Chemical shift values were referenced externally to hexamethylbenzene at 132.1 ppm, which is equivalent to tetramethylsilance at 0 ppm. The solid-state 13C CPMAS NMR spectra were divided into the seven common chemical shift regions: aliphatic C (0-45 ppm), methoxyl C (45-60 ppm), carbohydrate C (60-90 ppm), di-o-alkyl (90-110 ppm), aryl C (110-145 ppm), O aryl C (145-160 ppm) and carboxyl C (160-180 ppm) and the relative intensity for each region was determined by integration using Varian NMR 3.1A software package. Where chemical shift boundaries were moved in this work, in comparison to previous studies, this has been to facilitate the intensity corrections necessitated by spinning side bands (SSBs) appearing in the spectra acquired in this work.

Format:
The provided dataset consists of 2 files:

1. Excel file provides the chemical composition or organic matter in plant material, soil, and sediments. In this file detailed information of 31 samples (in order from 1 to 31) are provided including the type of sample, date of location, catchment/site name, GPS coordinates and the chemical composition or organic matter as revealed by 13C CPMAS-NMR.
2. The PDF file includes the 13C CPMAS-NMR spectra for each corresponding sample (in order from 1 to 31) in the excel file.

Data Location:

This dataset is filed in the eAtlas enduring data repository at: data\custodian\2019-2022-NESP-TWQ-5\5.8_Origin-detrimental-sediment