Analysis of Soil Fungal and Bacterial Communities in Tianchi Volcano Crater, Northeast China

High-altitude volcanoes, typical examples of extreme environments, are considered of particular interest in biology as a possible source of novel and exclusive microorganisms. We analyzed the crater soil microbial diversity of Tianchi Volcano, northeast China, by combining molecular and morphological analyses of culturable microbes, and metabarcoding based on Illumina sequencing, in order to increase our understanding of high-altitude volcanic microbial community structure. One-hundred and seventeen fungal strains belonging to 51 species and 31 genera of Ascomycota, Basidiomycota and Mucoromycota were isolated. Penicillium, Trichoderma, Cladosporium, Didymella, Alternaria and Fusarium dominated the culturable fungal community. A considerable number of isolated microbes, including filamentous fungi, such as Aureobasidium pullulans and Epicoccum nigrum, yeasts (Leucosporidium creatinivorum), and bacteria (Chryseobacterium lactis and Rhodococcus spp.), typical of high-altitude, cold, and geothermal extreme environments, provided new insights in the ecological characterization of the investigated environment, and may represent a precious source for the isolation of new bioactive compounds. A total of 1254 fungal and 2988 bacterial operational taxonomic units were generated from metabarcoding. Data analyses suggested that the fungal community could be more sensitive to environmental and geographical change compared to the bacterial community, whose network was characterized by more complicated and closer associations.

Development and Status of Active Volcano Monitoring in China

Following decades of geological surveys and studies, 14 active volcanic field have been identified in China. Evidence for Holocene volcanism in several of these areas highlights the need to understand and monitor volcanic hazards in those regions. Six volcano observatories have been established in the past 40 years accordingly. This work reviews China's national capability and history of volcano monitoring, with emphases on the Changbaishan-Tianchi Volcano Observatory and the Tengchong Volcano Observatory. The Changbaishan-Tianchi Volcano Observatory (CTVO) was constructed in 1996 and began monitoring in 1999, with limited recorded observations dating back to 1973. Currently, CTVO is the largest and most advanced observatory in China. The monitoring network of the CTVO incorporates 11 seismic and 15 GPS stations, 2 leveling routes, 3 gas geochemistry sampling points. The Changbaishan-Tianchi volcano experienced unrest during 2002-2005, evidenced in elevated levels of seismicity and ground deformation, as well as shifts in gas geochemistry. After 2006, the volcano returned to quiescence, with activities at background levels as recorded in 1973-2001. The monitoring network of Tengchong Volcano Observatory (TVO) incorporates 8 seismic stations, 20 GPS points, 95 leveling points, and 3 gas geochemistry sampling points. The observations made since 1965 indicate significant seismicity, with more than 3000 events recorded in 2011, mostly related to regional tectonics. Tengchong is known for its widespread hot springs, with temperatures up to 105 °C recorded at Dagunguo spring. The four other observatories are Longgang Volcano Observatory (LVO), Jingbohu Volcano Observatory (JVO), Wudalianchi Volcano Observatory (WVO) and Qiongbei Volcano Observatory (QVO). They are equipped with seismic, geodetic, and geochemical monitoring equipment. These areas saw only low levels of activity over the past several decades, but related fault systems are relatively active. In a relatively short time, China has gained considerable experience in observatory design and volcano monitoring and has trained up a sizeable task force, laying the foundation for sustained volcano monitoring at the national level. Future efforts must focus on maintaining and expanding observational capacity, as well as gaining better dynamic understanding to inform volcano hazard assessment.

Volcanic Processes and Magmatic Evolution of Tianchi Volcano, Changbaishan

The Changbaishan volcanic field located on the Gaima (Gaema, Gaiman) Plateau witnessed plateau-forming eruptions along with the uplift of the Gaima Plateau. The Tianchi basaltic lava shield volcano was formed at the main peak of Changbaishan, with cone construction eruptions that formed a huge and steep trachytic composite cone on the gentle lava shield. At the peak of the Millennium Eruption (ME), height of the eruption column (HB) reached 25 km and the bulk volume of tephra was about 120 km3. The ME eventually formed Tianchi caldera, after which several eruptions occurred, albeit of a much smaller scale.The magmas involved in the shield-forming eruptions are characterized by both alkalic series trachybasalt and basaltic trachyandesite and subalkalic tholeiite and basaltic andesite. In the cone-construction and ignimbrite-forming eruption stages, the magma is completely composed of alkalic series trachyte and comendite. The largest negative Eu anomalies observed in ME magmas indicate that plagioclase was strongly crystallized and differentiated.