Tham khảo tài liệu 'natural gas part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 192 Natural Gas All of the collected gases are CC 2-dominant the content varies from a minimum of vol. to a maximum of vol. . Fig. 6 shows a comparison of the CC2 values from the five monitored vents through a statistical distribution box plots . The CC2 leakage varies at the different vents being higher at the Black point and lowest at the Sink point. However median values are very similar for each vent suggesting a common degassing input linked to local tectonic features. In fact all the gas emission points are located along N-S E-W and NE-SW oriented active faults controlling the Aeolian Volcanic District. The main consequence of the presence of high levels of CC2 in the water chemistry is a generic acidification of the sea with a reduction in pH. This phenomenon affected both the macro and the micro biota. Regarding the macro life-forms in particular extensive damage to the benthic life-forms was observed this damage was mainly to the calcareous-shell organisms. Even though the damage to the benthic life-forms seems to be permanent there is a general healing of the ecosystem with the return of some species of fish. Another organism that was seriously affected by the presence of carbon dioxide is the Posidonia oceanica sea-grass. Cnce the Posidonia was dead the available substratum was colonized by other species such as more resistant algae. Cf the studied micro life-forms the viral abundance was affected by the presence of the gas vents with a decrease close to the carbon dioxide plumes. From these results it is possible to hypothesize that viruses can be less tolerant than prokaryotes to the carbon dioxide chemistry and this can have consequences on the biota equilibrium in the areas affected by increased levels of CC2 Manini et al. 2008 . Fig. 6. Box plots of soil gas CC2 data from the Panarea vents. The median values are very similar for each vent suggesting a common degassing input linked to local tectonics. Another example of toxic emanation .
