The effect of extreme temperatures on soil organic matter decomposition from Atlantic oak forest ecosystems.(ISCIENCE-D-21-01516R1)
This paper focuses on the soil organic matter, SOM, sensitivity to extreme temperatures and intends to relate it to soil organic matter properties which could be attached to the recalcitrance and lability of the organic substrates. The soil samples were collected in oak forests ecosystems in Ireland (Samples DC, G and K) and UK (Samples ROG, BW and NF) and represents the organic matter from different soil horizons: LF samples from the soil surface; the mineral soil under, M samples; and in the case of the samples from Ireland, an intermediate H layer in between LF and M horizons (H samples). SOM thermal properties were provided by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC) (TG-DSC) in an attempt of parametrizing SOM recalcitrance by the red-ox state. This is connected to the response of the soil samples to increasing and decreasing temperatures, measured by calorimetry as the heat rate of SOM decomposition. The calorimeter used is a model TAM III that allows the direct monitoring of the heat rates at different temperatures. The simultaneous TG-DSC gave the different soil thermal fractions of the samples and their heat of combustion, QSOM, values, connected to the degree of reduction of organic substrates by well-known principles. Here we attach the raw tabulated data from the TG-DSC measurements for all the samples used in this work as supplementary material S1. They are Excel files with columns representing, from left to right, time in seconds, temperature in Celsius degrees, the heat released in mW and the weight lost in mg. TAM III allows us to design a calorimetric heat wave and to monitor the heat rate from the soil samples at increasing temperatures from 20 ºC to 30, 40, 50 and 60 ºC, and to decreasing temperatures from 60ºC to 40 and 20 ºC. By this procedure we can compare which samples resist or do not resist the heat wave and to link it to their red-ox state by different statistical analysis. All the raw tabulated data from the calorimetric design with TAM III are provided here too, together with their baselines, as supplementary material S2. The Excel files show the heat flow rate in watts and joules at the different temperatures of the measurement. The files S2a are the data from UK LF samples, S2b the ones from UK Mineral samples, S2c are the calorimetric data from Irish LF samples, S2d the Irish H samples, and S2e the Irish M samples. Samples S2f and S2g are the baselines with the empty ampoules used in the calorimetric measurements, detailed for every experiment in the first folder of the Excel files. All the details dealing with the samples are explained in the paper.
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The procedures are explained in detail in the paper