In the area north of Lake Kivu, in the western part of the African Rift, deep fractures allow the uptake of gas, especially carbon dioxide. The Nyiragongo territory is located in the western part of the African Rift Valley. The deep fractures allow gases, especially carbon dioxide (CO 2 ), to rise. CO 2 is a heavier-than-air gas, asphyxiating, irritating to the eyes, nose and throat, and deadly at concentrations above 15%. The variation of CO 2 in the different stations allows us to study the behaviour of the Nyiragongo volcano although in our stations we have not reached the lethal concentration of CO 2 . The volcanic activity of Nyiragongo is therefore closely monitored by the inhabitants, and any news of increased activity agitates the inhabitants of the region, especially those living in the Nyiragongo territory. Here we report a short carbon dioxide monitoring time series for five stations (BUGARURA I, II, III, IV and MUNIGI stations). The various variations in CO 2 give us information about the activity of the Nyiragongo Volcano in the crater. The active volcanoes of the Virunga chain expose the Nyiragongo region to numerous natural hazards such as lava flows, gas plumes, dissolved gases in Lake Kivu and risks related to epidemiological diseases and armed conflicts.

Our study focused on "Extraction identification and characterization of saponins from the plant Myrica salicifolia Hochst. ex. A. Rich and molluscicidal activity test in vitro". The objective of this study is to extract the natural substances present in the different parts (leaves, bark of the stem and roots); isolate the saponins, characterize them by chromatography and determine the lethal dose of the saponins isolated against aquatic molluscs. After the analyzes, the Malacology laboratory of the LWIRO Natural Sciences Research Center (CRSN / LWIRO) took place in the Democratic Republic of Congo in the Kabare Territory. Phytochemical screening has enabled us to observe that saponins, quinones, phenols, lipoids, glycosides, terpenoids, tannoids, flavonoids, and alkaloids are in high concentration while steroids are moderately concentrated in the different parts of the plant. The thin layer chromatography of the saponins shows that the plant contains steroidal and triterpene saponins. The Myrica salicifolia Hochst plant. ex. A. Rich has molluscicidal activity, it can be used in the fight against molluscs Biomphalaria pfeifferi and Lymnaea natalensis intermediate hosts of bilharziasis and fascioliosis. The lethal doses (LD 50) of the saponin extracts from the bark of the roots and stems were 0.016 and 0.018 mg / mL respectively for Biomphalaria pfeifferi and 0.022 and 0.021 mg / mL for Lymnaea natalensis.