## 1 Introduction
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Reference** & **Area of Study** &
\begin{tabular}{c} **Data as Reported in the** \\ **Original Paper** \\ \end{tabular} & **Data Expressed in t/h** \\ \hline [PERSON] and [PERSON] 2002 [2] & Global ranges for CO\({}_{2}\) emission (GPP) & 4–740 gCO\({}_{2}\)/KWh \\ \hline \multirow{2}{*}{[PERSON] 2017 [3]} & Turkish geothermal fields & 400–1300 gCO\({}_{2}\)/KWh \\ \cline{2-3}  & Emissions of CO\({}_{2}\) from fossil fuels & 350–1100 gCO\({}_{2}\)/KWh \\ \hline [PERSON] 2003 [4] & Natural emissions from Krafla, Iceland & 200 gCO\({}_{2}\)/d m\({}^{2}\) \\ \hline \multirow{6}{*}{[PERSON] 2005 [5]} & Estimated CO\({}_{2}\) annual emissions from  several geothermal and volcanic  systems around the world & 0.01–1000 Mt/y & 1.14–144,077 \\ \cline{2-3}  & Pantelleria Island & 0.39 Mt/y & 44.5 \\ \cline{2-3}  & Mid-Ocean Volcanic system & 30–1000 Mt/y & 3422–144,077 \\ \cline{2-3}  & New Zealand & 0.44–0.95 Mt/y & 50.2–108.4 \\ \cline{2-3}  & Total estimated emission ranges & 200–1000 Mt/y & 22,815–144,077 \\ \hline \multirow{6}{*}{[PERSON] et al. 1999 [6]} & CO\({}_{2}\) fluxes from central Italy & & 30 \\ \cline{2-3}  & Stifone & & 0.15 \\ \cline{2-3}  & Klintuno & & 0.11 \\ \cline{2-3}  & Rasiglia & & 0.11 \\ \cline{2-3}  & Canino & & 0.7 \\ \hline Rogie, Kerrick, Chiodini and & Selvena & & 0.7 \\ \cline{2-3}  & Frontal 2000 [7] & Central Italy acquifers & 1–3 \(\times\) 10\({}^{11}\) mol/y & 502–1506 \\ \hline \multirow{2}{*}{Kerrick 2001 [8]} & Discharge from focused emission,  Central Italy & 1 \(\times\) 10\({}^{10}\) mol/y & 50 \\ \hline Carapezza 2011 [9] & Volcano Island & 1350 t/d & 56.3 \\ \hline \multirow{2}{*}{[PERSON] 2020 [10]} & Amiata Area (225 km\({}^{2}\)) emission & 13,350 t/d & 556.3 \\ \cline{2-3}  & shallow biogenic + deep origin carbon & & \\ \hline \multirow{2}{*}{[PERSON] 2016 [11]} & Emission CO\({}_{2}\) from sharp soil venters & & 6.8 \\ \cline{2-3}  & in Amiata area & & \\ \hline \multirow{2}{*}{[PERSON] 2020 [12]} & Bagni San Filippo area (1.7 km\({}^{2}\)),  combined soil emission end springs & 910 t/d & 37.9 \\ \cline{2-3}  & emission & & \\ \hline \multirow{2}{*}{[PERSON] 2004 [13]} & Emission deep CO\({}_{2}\) in Tuscan Roman & & 703 \\ \cline{2-3}  & Degassing Structure (TRDS) & & \\ \cline{2-3}  & Emission deep CO\({}_{2}\) in Campanian & & 351 \\ \cline{2-3}  & Degassing Structure (CDS) & & \\ \hline \multirow{2}{*}{[PERSON] 2004 [14]} & Flux of CO\({}_{2}\) is released into the  atmosphere in the entire anomalous  area of Central Italy & 9.7–17 Mt/y & 1107–1940 \\ \hline \multirow{2}{*}{[PERSON] et al. 2008 [15]} & Indirect estimation of CO\({}_{2}\) flux from  regional aquifers (tuscany and northern  Latium) & 0.9 \(\times\) 10\({}^{11}\) mol/y & 452 \\ \hline \multirow{2}{*}{[PERSON] 2005 [5]} & Maximum possible CO\({}_{2}\) flux from  geothermal and volcanic systems in  Iceland & 1.3 \(\times\) 10\({}^{9}\) kg/y & 148 \\ \hline \multirow{2}{*}{[PERSON] et al. 2006 [16]} & CO\({}_{2}\) fluxes from the Rotorua system in  New Zealand (8.9 km\({}^{2}\)) & 69.66 t/d km\({}^{2}\) & 26 \\ \hline \hline \end{tabular}  
* In addition to the above mentioned data, for the Italian case, some databases have been developed, such as the MagaDB database ([[http://www.magadb.net/](http://www.magadb.net/)]([http://www.magadb.net/](http://www.magadb.net/)) (accessed on 12 May 2021)), which contains available data on the chemical composition, and sometimes the flow rates, of gas emitted from several types of gas sources.  
\end{table} 
Table 1: CO\({}_{2}\) emission in main volcanic and non-volcanic areas *.