VELVET: measuring chamber for studying emissions of Biogenic Volatile Organic Compounds (BVOCs) by plant species in temperate and tropical climates.

Distribution of VOC emissions by species sampled in 3 of the island’s forests: Mare-Longue endemic forest, high altitude forest near OPAR-Maïdo, Plaine des Fougères cloud forest. Blue = isoprene, orange = sum of monoterpenes, grey = sum of benzene, toluene, ethylbenzene and xylenes.

The VELVET chamber (VOC experiments on leaves with the vegetation enclosure technique) was designed and used to measure emissions of volatile organic compounds (VOCs) from plant leaves. Measurements were carried out on species in temperate climates: Norway spruce (Picea abies), Norway beech (Fagus sylvatica) and Norway hazel (Corylus avellana) in the Puy de Dôme region of France. In a tropical region (Réunion Island), the VELVET-RUN project sampled 10 of the island’s most representative native and exotic species in the Mare-Longue forest, a high-altitude forest close to the Maïdo Atmospheric Physics Observatory, and in the cloud forest at Plaine des Fougères. The study revealed that the emissions of these species were influenced by spatial variability, their environment and the type of forest. In particular, this study marked an important step forward by capturing the emissions of species endemic to the island for the first time. Following on from the VELVET-RUN project, the TROPIVOC project aims to continue monitoring VOCs (concentration and evolution) over the short/medium/long term in the Mare-Longue forest. The data collected will enhance the inventory of biogenic emissions on the island, improving model simulations by incorporating these new measurements.

Full reference : Rocco, M., Brugère, E., Magand, O., Borbon, A., Colomb, A., Bouvier, L., Baray, J., Duflot, V., Ribeiro, M., Picard, D., Metzger, J., Stamenoff, P., Benoit, Y., Ah-Peng, C. VELVET: an enclosure vegetation system to measure BVOC emission fingerprints in temperate and tropical climates. Frontiers in Environmental Science12, 1372931.

Local contact :

External contact : (Manon ROCCO, LCE/IMBE)

As part of the 6th call for transnational and interdisciplinary access to research infrastructures under the European ATMO ACCESS program, the project by David Beilman (University of Hawaii at Manoa, Department of Geography & Environment) has been accepted by the ATMO ACCESS evaluation panel.

Mare au Thym, Bélouve, in high Sphaignes marshes

Project title and acronym: Long-term sensitivity and resilience of montane peatland carbon on La Reunion (PeatCReu24)

Scientific background: As much as one-third of the global soil carbon pool is estimated to be held in peatland ecosystems globally, despite covering only a few percent of total land area. The unique environment and extreme high carbon density of peatlands makes their potential carbon flux to the atmosphere a global change threat under disturbance by land use, fire, and climate change. Tropical peatlands are the least studied and understood of all peatlands globally, yet can be abundant on high tropical volcanic islands, such as the Hawaiian Archipelago and la Reunion. They are ‘triple hotspots’ of biodiversity, carbon storage, and unique sedimentary archives of past ecosystem sensitivity and resilience in the peat they sequester over thousands of years.

Scientific objectives of the project: The project proposes to further investigate an important study site on La Reunion for comparison to Hawaii. The region is the Plaine ds Marsouins, where our preliminary data shows that peatlands have existed here for more than twenty thousand years. This spans the climate warming following the Last Glacial Maximum, allowing comparison of warming effects in the Pacific and Indian Ocean regions in the same tropical montane environments. The physical access work plan would center on visiting the region for a period of two weeks. The primary work would consist of three field tasks. First, we would conduct detailed surveys including mapping the peat depth via a network of soil probe locations and basal samples to better estimate of volumes and ages for carbon storage estimation. Second, we would collect rain and surface waters and plants to better characterize the water isotope variation and their imprint on leaf tissue chemistry. Third, we would identify and core the deepest and oldest part of the peatland to maximize our information and peat-core approach to long-term ecological change. The material would be transported back to Toulouse to the CRNS lab for further analysis and subsampling.

Interdisciplinarity of the project: This project is to study long-term ecosystem function in the context of the carbon cycle and the role of carbon-rich ecosystems and their storage and potential release of atmospheric carbon dioxide.

Innovation potential / Impact: The proposed work seeks to expand our preliminary findings and to further our comparison of tropical mountain forest ecosystems in the Pacific and Indian Ocean regions. The novel aspect of this work is the long-term understanding of ecosystem history and the relationship between carbon sequestration and global change drivers like climate and disturbance. The Last Glacial Maximum age of the Plaine des Marsouins peatlands, and its comparison to similar ancient landscape in Hawaii, is a first-of-its-kind comparison. Such a long-term perspective of these critical zone processes that is possible with study of these sites is rare. Finding and explicitly comparing similar sites in tropical mountain ecosystems has never been done before.

Request for access to OSU-Réunion platforms: OPAR and OZC-R

Access period: September 1-15, 2024

Administrative and logistical support: No administrative assistance is needed. Logistic assistance would be in the form of accommodation and transportation to the study site.

Availability and use of data and results: All data generated from the access would be shared with the facility and be publically available. Our approach to data repositories is to use more than one to ensure that data is available to all interested parties.

Distribution of results: The ongoing collaboration aims to publish a number of papers and conference presentations about these unique ecosystems and their comparison across La Reunion and Hawaii. These have already started.

Initial results from a previous mission (ANR Atmo-plastic) show that the environmental archive at Plateau de Thym dates back more than 20,000 years. This would retrace the last climatic warming followed by the last glaciation (Late Glacial Maximum), enabling a comparison of ecological history and climatic changes between the Indian and Pacific Oceans. This comparison between Reunion Island and Hawaii is a new opportunity to better understand the critical zone and ecosystem dynamics over the long term.

New EU Project IRISCC Launched to Empower Climate Change Resilience – La Réunion, Indian Ocean, France – April 4, 2024

A new, ambitious European Research Infrastructure project, IRISCC, focusing on climate change driven risks has officially started on April 1st. The project is coordinated by Natural Resources Institute Finland (Luke) and brings together 80 partners from across Europe and integrates research services by 14 research infrastructures (RIs) and e-infrastructures.

IRISCC, with a budget of almost €15 million, is a 54-month project with a mission to bolster society’s capacity to tackle climate change risks and build resilience. We achieve this by offering access to interdisciplinary research platforms and data for researchers focusing on climate change risks. “Understanding the climate change driven risks and being prepared to adapt to them is becoming even more crucial for our societies in the near future” Janne Rinne, IRISCC co-coordinator.

Access to a Wealth of Resources
IRISCC offers access to complementary and interdisciplinary European and national RIs, encompassing observatories, experimental facilities, advanced modelling tools, and robust data infrastructures. OSU-Réunion (Observatoire des Sciences de l’Univers de La Réunion, Université de La Réunion, CNRS, IRD, Météo-France) is proud to contribute by offering access to interdisciplinary platforms like OPAR which is an atmospheric mountain observatory at La Réunion (-21.0797°N 55.3831°E) accommodating a large sector of ACTRIS and ICOS instrumentation. Scientific areas are available to enable the installation of new measurements.

Boosting Research and Evidence-Based Decisions
IRISCC fosters challenge-driven and interdisciplinary research on climate-change-related multi-hazard risks. This empowers informed decision-making, propelling Europe’s adaptation and resilience strategies.

IRISCC’s Key Objectives:

  • Support evidence-based policymaking for climate change adaptation and risk management.
  • Facilitate high-quality research on climate change driven risks and its components.
  • Provide a user-friendly, comprehensive service portfolio for climate change risk research.
  • Ensure seamless integration across RIs and harmonise their access & data policies.
  • Foster user engagement and co-creation of services with researchers and other stakeholders.

Investing in the Future
IRISCC is committed to open knowledge sharing and wide capacity building. The project offers training programs to equip the new generation of researchers with the skills to use these integrated research services for impactful climate change risk research. “Dissemination and exploitation of the services and training offered by the project is one of our key activities”, Päivi Haapanala, IRISCC Project manager.

Targeting a Broad Spectrum of Stakeholders
IRISCC serves a diverse range of users, including the research community, commercial entities, local, national and international risk managers, international agencies, policymakers, and society at large.

IRISCC marks a significant step forward in empowering a collective response to climate challenges. By harnessing the collective expertise of European RIs, this project equips us to build a more resilient future. IRISCC is funded by the European union under the Grant Agreement number: 101131261.

Atmospheric Mercury: A decade of observations on Amsterdam Island

(credit: TAAF – Terres australes et antarctiques françaises)

The Minamata Convention, which came into force in 2017, aims to protect human health and the environment from the harmful effects of mercury by reducing associated anthropogenic emissions and environmental levels. The Conference of the Parties must periodically evaluate the effectiveness of the Convention using existing monitoring data and observed trends. Monitoring atmospheric mercury levels has been proposed as a key indicator. However, data gaps exist, particularly in the Southern Hemisphere. The article relayed in the INSU brief (link) presents over a decade of atmospheric mercury monitoring data on Amsterdam Island (TAAF – Indian Ocean). The data (ambient air concentrations of elemental and oxidized mercury gas species + annual wet deposition fluxes of total mercury) are made available to the community to support decision-making and scientific advances in relation to the dedicated international issue. It is important to note that this work is complemented by parallel monitoring of some of these compounds at OPAR-Maido (OSU-Réunion) since 2017. The data collected at OPAR-Maido, which are not shown in this article, will strengthen the monitoring of these compounds at the scale of the Indian Ocean basin, and contribute to a better understanding of the current state and future of this pollutant in this part of the world.

Complete reference : Magand, O., Angot, H., Bertrand, Y., Sonke, J.E., Laffont, L., Duperray, S., Collignon, L., Boulanger, D., Dommergue, A., 2023. Over a decade of atmospheric mercury monitoring at Amsterdam island in the French southern and Antarctic Lands. Sci Data 10, 836 (2023).

Local contact : Olivier Magand, OSU-Réunion (

External contacts : Aurélien Dommergue – Research professor at Grenoble Alpes University’s Institute of Environmental Geosciences (IGE) (, Hélène Angot – CNRS researcher at the Institute of Environmental Geosciences (IGE – OSUG) (, Yann Bertrand – CNRS Instrumentation Engineer at the Institute for Environmental Geosciences (IGE) (

Overview of atmospheric mercury species monitored on the subtropical island of Amsterdam since 2012. Gaseous elemental mercury (GEM) is the atmospheric species currently monitored in parallel to OPAR-Maido since 2017. Figure taken from Magand et al. 2023.

IR ILICO SNO Dynalit – Coastline observation

Discover a short video presenting the activities of the Service National d’Observation Dynalit, the certified service focused on the study of coastal dynamics and coastline. The Hermitage transverse site is also featured. Thanks to the OSU-Réunion drone service for the local shots.

Rapid destruction of stratospheric ozone due to massive injection of water vapour by the Hunga Tonga-Hunga Hapa’ai volcano.

(credit: René Carayol, Université de la Réunion)

On January 15, 2022, the eruption of the Hunga Tonga-Hunga Ha’apai volcano severely disturbed the upper atmosphere, emitting ash, sulfur dioxide (SO2) and other gases, as well as an exceptional quantity of water vapor (around 150 million tons) into the stratosphere at an altitude of over 30 km. This rare event was an opportunity to study chemical processes in a volcanic plume shortly after an eruption from the Maïdo observatory. Volcanic eruptions can affect climate and ozone chemistry. Understanding these interactions is essential to improve modeling of environmental processes and future climate evolution.

Our study combined in situ measurements from weather balloons, ground-based remote sensing observations and satellite data to understand the initial impact of the eruption on stratospheric ozone. In just one week, stratospheric ozone concentrations over the south-west Pacific and Indian Oceans fell by 5%. This decrease is particularly significant when compared to the Antarctic ozone hole, where up to 60% of the ozone is destroyed each year over several months. The humidification of the stratosphere after the eruption enabled the rapid formation of small droplets of sulfuric acid from SO2. On the surface of these particles, chemical reactions convert chlorine compounds into ozone-destroying molecules. This ozone depletion in the tropical region exceeds that of previous eruptions, underlining the exceptional nature of the Hunga Tonga eruption.


LACy/OSU-R Scientific contact : Stéphanie Evan, LACy (

Rapid ozone destruction following the eruption of Hunga Tonga: Following the eruption of Hunga Tonga, a measurement campaign using meteorological balloon instruments took place at the Maïdo observatory (photo left). The plume dynamics highlighted the volcanic injection of water vapor (H2O), sulfur dioxide (SO2) and hydrogen chloride (HCl), promoting rapid conversion of chlorine compounds to chlorine molecules at the surface of hydrated volcanic aerosols, and ozone depletion in the stratosphere. The ozone profile for January 22, 2022 (black line) contrasts with the climatology of La Réunion (red line), showing a marked decline.

Start of the TNA ATMO-ACCESS NetAeFoCs project at OPAR-Maido: Study of interactions between aerosols, fog and clouds under natural and anthropogenic influences.

View of the ACES instrumented container (TNA ATMO-ACCESS NetAeFoCs project) at OPAR-Maido and some of the team members from Stockholm University (Department of Environmental Sciences – ACES) and OSU-Réunion (October 12, 2023) (credit: Olivier Magand, OSU-R).

As part of the TNA ATMO-ACCESS NetAeFoCs project, the team(*) from Stockholm University (Department of Environmental Sciences – ACES), supported by and in collaboration with the Observatoire des Sciences de l’Univers de La Réunion (OSU-R), the Laboratoire de l’Atmosphère et des Cyclones (LACy) and French partners carrying out continuous on-site measurements (LaMP, LSCE…), is aiming to collect atmospheric observation data at the Observatoire Physique de l’Atmosphère de La Réunion (OPAR) at Le Maïdo (OSU-R measurement station). ), aims to collect data from atmospheric observations at the Observatoire de Physique de l’Atmosphère de La Réunion (OPAR) at Le Maïdo (OSU-R’s measurement station) to fill in the knowledge gaps that are absolutely essential to understand the improvement of models dedicated to the functioning of the atmospheric system (molecular model, cloud distribution…) on a regional or even global scale.

At the Maïdo observatory, we plan to record the composition and properties of aerosols and clouds in detail, using state-of-the-art observational equipment. The instruments are installed in a specially designed mobile laboratory (20-foot container). The latter has already been used to study aerosol-mist-cloud interactions in Italy’s Po Valley (FAIRARI campaign supported by ATMO-ACCESS) and during the ARTofMELT 2023 expedition aboard the Swedish icebreaker Oden. The OPAR at Maïdo is the 3rd major measurement station visited by this mobile laboratory.

After several weeks of ocean crossing, the container was finally installed at the Maïdo observatory on October 10, 2023, in a sea of clouds revealing the site’s potential for studying this component. The field campaign officially began on October 12, after 2 days of set-up, and will continue for at least 6 months, with continuous measurements of aerosols, clouds and atmospheric chemical compounds during the austral summer and cyclone season. In addition to ATMO-ACCESS, the field campaign is supported by the European Research Council and the Knut and Alice Wallenberg Foundation, Sweden.

(*) Project leaders (Ilona Riipinen, Claudia Mohr – currently at PSI, Switzerland – and Paul Zieger), PhDs (Almuth Neuberger, Lea Haberstock and Fredrik Mattsson), post-docs (Liine Heikkinen and Yvette Gramlich) (

TNA project contact : Paul Zieger (

OSU-Reunion coordinator contact :  Olivier Magand (

Schematic view of the atmospheric measurement instruments deployed during the OPAR-Maido campaign (OSU-Reunion) in the ACES container (credit: Department of Environmental Sciences, Stockholm University).

Training in forest ecology at the University of Mauritius (UoM)

As part of an ERASMUS+ program, three OSU-Réunion employees visited Mauritius. Hosted by Vincent Florens (Professor of Ecology at the Department of Biosciences and Ocean Studies, University of Mauritius) and Claudia Baider (Head of the National Mauritius Herbarium), they took part in a field training course on ecosystem preservation and restoration.

The course, which took place mainly in the field, covered two themes relating to island rainforests:

  • the problem of invasive species (Macaque monkey, wild pig, or Guava and Ravenale) which threaten endemic plant (Tambalacoque, Harungana) and animal (Pink pigeon, Bat) species in Mauritius.
  • carbon sequestration measures in tropical island forests.

A visit to the Ebony Forest reserve with Nicolas Zuel (Conservation Manager) also provided an insight into the restoration and preservation actions implemented by these semi-private players, as well as the difficulties encountered.

This bilingual mission to Mauritius, rich in scientific and technical exchanges, brought real added value to studies of forest ecosystems on Reunion Island.

“Complete depletion” of gaseous elemental mercury observed in the Piton de la Fournaise volcanic plume (April-June 2018 eruption): Proposal of a mercury trapping process by volcanic aerosols

We’ve long known that volcanoes emit mercury, a powerful neurotoxin, into the atmosphere. However, the behavior and transformations of mercury after its emission in a volcanic plume, an extreme and chemically active environment, remain largely unknown. Knowledge of these transformations is of great importance, as they determine whether the emitted mercury compound is transported on a global scale via atmospheric circulation, or deposited locally and regionally at short distances from the emission source. We show, via this study carried out on Reunion Island, using data collected at the Observatoire de Physique Atmosphérique du Maido (OPAR, OSU-R) and around the Piton de la Fournaise volcano during the April-June 2018 eruption, that mercury present in the volcanic plume can be efficiently transformed into rapidly sedimenting chemical compounds that are susceptible to leaching by precipitation. This study implies that terrestrial volcanism can not only emit mercury directly into the atmosphere, as has been previously accepted for many years, but also induce chemical reactions that remove it indirectly and rapidly. Although observation of this process would reduce the mass of mercury emitted and spatially distributed in the atmosphere on a hemispheric or even global scale, the said process would increase mercury deposition and human exposure in active volcanic regions around emission sources.

Reference : Koenig, A., Magand, O., Rose, C., Muro, A., Miyazaki, Y., Colomb, A., Rissanen, M., Lee, C., Koenig, T., Volkamer, R., Brioude, J., Verreyken, B., Roberts, T., Edwards, B., Sellegri, K., Arellano, S., Kowalski, P., Aiuppa, A., Sonke, J., Dommergue, A. (2023). Observed in-plume gaseous elemental mercury depletion suggests significant mercury scavenging by volcanic aerosols. Environmental Science: Atmospheres. 10.1039/D3EA00063J.

Scientific contact OSU-R: Olivier Magand, OSU-R (

Scientific contact IGE: Alkuin Koenig, IGE (

Synthetic diagram of the proposed GEM atmospheric depletion process
(© Alkuin Koenig, IGE)