Inferences from plants studies and environmental radioactivity at the Maccalube natural reserve (Ag)

Catania (Italy)

This research is devoted to the characterization of the Maccalube di Aragona reserve (Ag, Italy) in terms of environmental radioactivity and plants’ activity. The interest for such area is born in the context of mud volcanoes dynamics, being the reserve a wide area where several gryphons and pools are located. The latter emit for 97% methane and, in a small quantity, hydrocarbons and water with high salinity [Etiope et al. GRL 2002; Bonini, Tectonophysics 2009; Cangemi & Madonia 2013]. Time to time, one of these volcanoes undergoes a paroxysmal as occurred in the past 2014, when two children died for a sudden explosion. The shallow activity of these emitting centers and/pools is related to the fluid in overpressure state which make their way to the surface producing the typical cone shape. It is well known the mud volcanoes are hazardous and recently much attention is devoted to them. Promud project (https://progetti.ingv.it/it/promud) aims at characterizing the reserve from geophysical, seismological, geodetical, and plant biodiversity point of view in order to develop a protocol also for civil protection. In line with previous thoughts, we performed two field surveys for assessing the environmental radioactivity. Thus, we measured, in the first campaign, radon in soil gas, coupling the detector RAD7 Durridge with a surface soil accumulation chamber. Then, in the second one, we performed radon (222Rn) and thoron (220Rn) measurement by using the same instrumentation, set up and protocol. Such recordings allowed us to better constrain the source location in a compact clay layer.
Additional information about the interaction between soil properties and the reservoir can be obtained by investigating the plants able to survive in this extreme environment. Abiotic stressors in agriculture, such as drought, salinity, heavy metals and other environmental conditions, pose significant challenges to agricultural productivity [Agudelo et al. Foods 2021]. These stressors disrupt vital physiological processes resulting in decreased crop yields and compromised quality. To reduce the impact of abiotic stresses, strategies such as cultivating stress-tolerant plants and implementing effective management practices could enhance plant resilience. Consequently, this aspect of the investigation seeks to enhance comprehension of these species specialized metabolite production and their responses to the stress conditions present within “Maccalube” mud volcanoes. Furthermore, the study aims to obtain data pertaining to the dynamics of these volcanoes. The results of this study may also elucidate the advantages of these plants, and the potential use for agricultural purpose. To this end, Suaeda vera, a halophytic plant belonging to Amaranthaceae family with the ability to survive within extreme environmental conditions, has been collected. A preliminary phytochemical characterisation of the hydroalcoholic extract of S. vera aerial parts was conducted via liquid chromatography-high resolution mass spectrometry (HRESIMS) and NMR. This analysis led to the identification of a plethora of specialized metabolites belonging to various classes, such as flavonoids, phenolic acids, and their glycosides, alkaloids, and fatty acids. A metabolomic profile of the plant was also compared with that of a
sample of S. vera, which was collected in a different reserve located in Saline di Cervia (Ravenna, Italy) and environmental conditions. This showed a similar metabolomic profile, with the exception of sulphated flavonoids, which were observed to be synthesised only by the plant collected in the Maccalube area.