This study investigates non-biological soil CO₂ ventilation in a semiarid Mediterranean shrubland and standardizes the criteria for its detection. Ten ventilation events were identified during the SCARCE (Synchronized Characterization of Aerosol, Radon and Carbon dioxide Exchanges in drylands) campaign, with several atmospheric parameters acting as drivers. Surface pressure emerged as the primary driver at the site, while friction velocity and boundary layer turbulence were also found to be relevant, highlighting the value of Doppler lidar for soil–atmosphere exchange studies.

Humidification of air reduces the abundances of dry-air gas components such as oxygen, explaining why tropical humidity can be "stifling". This is overlooked due to the common expression of gas concentrations as fractions of dry air. Such neglect of water vapour also masks the key role of its sources and sinks in activating transport mechanisms of other gases. Humidity should be quantified whenever reporting gas concentrations.

This manuscript demonstrates that a mass-based (inertial) framework is essential to the correct definition of diffusive transport, and therefore for defining Ficks first law. It invalidates the molar-based framework used by Roderick and Shakespeare (2025) to identify the contribution of the Soret effect (mass transport due to a temperature gradient) to open-water evaporation.

The laws of physics show that leaf oxygen is not photosynthetically enriched but extremely dilute due to the overwhelming effects of humidification. This challenges the prevailing diffusion-only paradigm regarding leaf gas exchanges because non-diffusive transport is required. Such transport also explains why fluxes of carbon dioxide and water vapour become decoupled at very high temperatures, as has been observed but not explained by plant physiologists.

This study investigated soil respiration and the main factors involved in a semi-arid environment (olive grove). For this purpose, 1 year's worth of automatic multi-chamber measurements was used, accompanied by ecosystem respiration data obtained using the eddy covariance technique. The soil respiration annual balance, Q₁₀ parameter, rain pulses, and spatial and temporal variability of soil respiration are presented in this paper.