Arndt Schimmelmann

Arndt Schimmelmann

Collaborative research projects with the EOS group at Vietnam National University in Hanoi

(Texts below from HOOSIER GEOLOGIC RECORD, 2016-17, Alumni Newsletter of the Department of Earth and Atmospheric Sciences, Indiana University)

Methane is a potent atmospheric greenhouse gas that originates mostly from agriculture and fossil fuel industry.

Arndt Schimmelmann’s research group discovered that abundant subterranean porosity in Vietnamese karst  mountains filters out atmospheric methane. Tropical karst represents a giant spongy biogeoreactor where ‘methane-eating’ microbes are thriving in humid and warm conditions. The same principle could be used in biogeo-engineered reactors where microbes selectively remove methane from industrial and agricultural point sources.

Above: Graphical abstract for a publication in Chemical Geology

While working in rural northern Vietnam where deforestation and poverty often necessitate human habitation in ‘mud houses,’ Schimmelmann’s team noticed that regional soil in walls and floors contains enough natural radioactivity to emit hazardous radon levels far exceeding EPA safety thresholds. Especially the radon-220 isotope with a short half-life of ca. 55 seconds poses a health hazard that cannot be mitigated by venting of room air. Radon-220 diffuses out of porous mud into room air from where inhalation and a chain of radioactive decay reactions of radon and its metallic daughter products can induce lung cancer.

Mud-built homes in northern Vietnam tend to emit high concentrations of radioactive radon gas.

This unexpected finding in mud houses is unique to living conditions in developing countries. We engage in collaborative research with Vietnamese scientists to develop affordable remediation strategies and improve public health, for example by sealing porous surfaces in mud houses with a gas-impermeable coating. Ongoing experiments in an authentic Vietnamese mud house explore the utility of inexpensive and non-toxic sodium silicate solution that soaks into the mud surface, reacts with carbon dioxide from room air, and precipitates a clear seal of silica gel. A second coat with added pigmentation of locally available limestone dust can greatly beautify the interior of a mud house and enhance acceptance of remediation measures.

Open plastic boxes were fitted with foam insulating strips and were pressed against treated sections of mud walls to trap a constant volume of air that was in contact with a defined area of mud wall. The exhalation of radon and thoron was measured in closed-circuit mode with SARAD RTM2200 and RAD7 instruments at an air flow rate of 1 liter per minute. Proper surface treatment reduced thoron exhalation to below detection limits (Bạch Đích commune, Yên Minh district, Hà Giang province – near the Vietnam – China border, December 2016).
Arndt Schimmelmann and fellow EOS members pose in front of newly built mud-house in a Hanoi suburb in November 2017. The model mud-house was specifically built for scientific experiments aiming at (1) developing recommendations for affordable and reasonable detection methods for radon and thoron in mud-built homes; (2) assessing the concentrations and distributions of thoron and radon in mud-house air; (3) devising affordable, non-toxic and socially acceptable methods for sealing of porous mud surfaces in homes to mitigate the radiation geohazard and to improve public health.

As a third collaborative research project with Vietnam National University in Hanoi, the laminated sediment from a volcanic maar lake in central Vietnam near Pleiku is being explored as a geological archive for prehistorical monsoon strength and typhoon occurrence. The record of distinct flood layers of the past can be radiocarbon-dated and may offer a reliable statistical basis to judge the effects of climate change on modern precipitation patterns in central Vietnam.

Sediment coring activities in Biển Hồ maar lake, Central Highland of Vietnam, November 2017. The image above shows inner tubes from trucks provide flotation. The entire platform with anchors cost only about $150 and worked extremely well. We pulled 20 wonderful sediment cores from up to 21 m water depth with penetration into sediment of up to 3.5 meter.
Related publications
  1. Arndt Schimmelmann, Hướng Nguyễn-Văn, Dương Nguyễn-Thùy, Jan P. Schimmelmann, Antti E.K. Ojala, Nguyệt Nguyễn-Ánh, Quốc Trọng Đỗ, Dương Thùy Nguyễn, Phương Hòa Tạ, Vũ Huỳnh-Kim, Nhi Quỳnh Phạm-Nữ, Bernd Zolitschka and Ingmar Unkel (2018), Maar sediment in central Vietnam Highland near Pleiku: An archive of regional monsoon intensity? An abstract summited to IAVCEI – 7th International Maar Conference, Olot, Spain, 2018.
  2. Schimmelmann, J.P., H. Nguyễn-Văn, D. Nguyễn-Thùy, A. Schimmelmann, A.E.K. Ojala, B. Zolitschka, N. Nguyễn-Ánh (in review) Monsoon-related rainfall recorded by mineral-rich flood layers in Vietnamese maar sediment. European Geosciences Union (EGU) General Assembly 2018, 8-13 April 2018, Vienna, Austria.
  3. Nguyễn Thị Ánh Nguyệt, Nguyễn Thùy Dương, Arndt Schimmelmann & Nguyễn Văn Hướng, 2018. Human exposure to radon radiation geohazard in Rong Cave, Dong Van Karst Plateau Geopark, Vietnam. Vietnam Journal of Earth Scicences (Accepted)
  4. Schimmelmann, A., Dương Nguyễn-Thuỳ, Hướng Nguyễn-Văn, Nguyệt Thị Ánh Nguyễn, Minh Ngọc Schimmelmann (2017) Thoron (220Rn) exhalation into room air of earthen dwellings in northern Vietnam: Recognition of health geohazard and strategy for remediation. 14th International Conference on Gas Geochemistry 2017, ICGG-14, 24-28 Sep., Wrocław and Świeradów, Poland, Book of Abstracts 139-141 [PDF].
  5. Duong Nguyen-Thuy, Huong Nguyen-Van, Nguyet Thi-Anh-Nguyen, A.Schimmelmann, M.N. Schimmelmann, 2017. Recognition of health geohazard of thoron (Rn-220) exhalation into room air of earthen dwellings in northern Vietnam. 4th International Conference on Radioecology & Environmental Radioactivity, 3-8 September 2017, Berlin, Abstracts Book, ISBN 978-2-9545237-7-4  [PDF] [Poster JPEG]
  6. Nguyễn-Thuỳ, Dương, A. Schimmelmann, Hướng Nguyễn-Văn, Agnieszka Drobniak, Jay T. Lennon, Phương Hòa Tạ, Nguyệt Thị Ánh Nguyễn, 2017. Subterranean microbial oxidation of atmospheric methane in cavernous tropical karst. Chemical Geology, Volume 466, 5 September 2017, Pages 229-238 []  [Graphical abstract JPEG]
  7. Lennon, Jay T., Dương Nguyễn-Thùy, Trang Minh Phạm, Agnieszka Drobniak, Phương Hòa Tạ, Ngọc Ðức Phạm, Thomas Streil, Kevin D. Webster, A. Schimmelmann (2017) Microbial contributions to subterranean methane sinks. Geobiology 15 (2), 254-258.
  8. Nguyễn-Văn, Hướng, Dương Nguyễn-Thùy, Jan P. Schimmelmann, Bernd Zolitschka, Thân Tạ-Văn, Nguyệt Nguyễn-Ánh, Phương Tạ Hòa, Dương Nguyễn-Thùy, Thắng Lê-Quyết, Quỳnh Nhi Phạm-Nữ, Vũ Huỳnh-Kim and Arndt Schimmelmann (2017) Exploring the paleoenvironmental potential of laminated maar sediment in central Vietnam: An archive of regional paleo-flooding? PAGES Zaragoza 2017 5th Open Science Meeting ”Global challenges for our common future – a paleoscience perspective”, 9-13 May, 2017, Zaragoza, Spain, Session #16: Multidisciplinary reconstruction of paleofloods. p. 325 in abstract book [Abstract PDF] [Poster JPEG]
  9. Nguyen-Thuy, Duong, A. Schimmelmann, Phuong Ta Hoa, Agnieszka Drobniak, and Minh Schimmelmann (2016) Radon and carbon dioxide in northern Vietnamese limestone caves. 5th International Conference on Earth Science & Climate Change, July 25-27, 2016, Bangkok, Thailand.
  10. Schimmelmann, A., Jay T. Lennon, Duong Nguyen-Thuy, Phuong Ta Hoa, Agnieszka Drobniak, Kevin D. Webster, and Minh Schimmelmann (2016) Vietnam’s tropical karst is a sink for atmospheric methane greenhouse gas. 5th International Conference on Earth Science & Climate Change, July 25-27, 2016, Bangkok, Thailand.
  11. Đặng PT, Nguyễn-Thùy D, Nguyễn-Ánh N, Nguyễn-Văn H, Schimmelmann A, 2016. Preliminary investigation into radiological environment in Dong Van district, Ha Giang province. VNU Journal of Science – Earth and Environmental Sciences Vol. 32, No. 2S, 2016 [Full PDF].
  12. Nguyễn-Thùy D, Nguyễn-Văn H, Schimmelmann A, Nguyễn-Ánh N, Đặng PT, 2016. Radon concentrations in karst caves in Dong Van karst plateau. VNU Journal of Science – Earth and Environmental Sciences Vol. 32, No. 2S, 2016 [Full PDF].

Geosciences are improving the lives of people in Vietnam