Search

Since the Industrial revolution and due to increasing anthropogenic emissions, the composition of the atmosphere has been modified, leading to climate change and pollution. The impacts of pollution were depicted through paintings and writing from the beginning of the 19th century, but pollution measurements are relatively recent. In order to obtain ancient air pollution data, proxies in urban area need to be found.Black crusts formed on limestone and marble monuments in urban area seem to be a good candidate as local proxy. Mainly composed of gypsum (CaSO4.2H2O), they are a chemical alteration pattern resulting from the reaction of the dissolution of the calcite (CaCO3) of the stone and of sulfation by sulphur dioxide (SO2) from the atmosphere. Particulate matter accumulates in the newly formed gypsum layer in sheltered area from the rain, thus giving the black crust a passive sampler potential.To use black crusts as past air pollution archives, samples were collected at Père Lachaise cemetery (Paris) on ancient, dated (1820-1887) and unrestored limestone or marble tombs. Different types of analyses were performed to study sample morphology (by Optical Microscope), particulate matter (by Scanning Electron Microscopy) and chemical composition (especially major elements and trace metals by ICP-AES, LA-ICP-MS). Results underline two important features to use black crusts as past air pollution archives. First, the low variability of chemical composition of black crusts from Père Lachaise cemetery highlights that the black crusts are representative of the site and register the background pollution. Then, the morphology (laminar vs. dendritic) of black crusts is a key parameter to sample black crusts as the stratigraphy is much better preserved in laminar black crusts.

A large number of stained glass windows were installed from the 13th century. During the Middle-Ages, most of glass pieces have a Si-K-Ca composition with a relatively low SiO2 content, but high content of K2O and CaO. This chemical composition means that medieval stained glass deteriorates during environmental exposure, from climate and environmental pollution. These alterations are manifested in the form of an alteration layer and secondary phases (mainly gypsum or syngenite). The alteration layer is generally depleted in K and Ca, but rich in Si, Al and Fe. Its thickness varies up to 300 µm after 6 or 7 centuries of alteration. In order to reconstruct the alteration history and predict the deterioration of stained glass windows in the future, it is necessary to determine alteration rates as a function of the climate and environmental parameters.Several methodologies can be used to achieve this. First, short-term exposures or laboratory experiments can assess the first stages of the alteration and short-term kinetics. From these results, dose-response functions (DRF) were established for sheltered and unsheltered rain conditions. They correlate relevant environmental factors (temperature, rain quantity, rain pH, relative humidity, SO2 concentration) with the response of the materials in terms of alteration layer thickness. The second methodology consists in laboratory experiments that aim at parametrizing kinetic laws as a function of specific parameters (temperature, pH of rain, and relative humidity). These kinetic parameters do not directly consider pollution, but they can be extrapolated over long periods and can be inputs to geochemical models. In this study, we have compared both methodologies to simulate the alteration of a model stained glass at different European sites (using data from the ICP-Materials program). Both models give good results, but the geochemical model tends to underestimate the alteration at polluted sites. This indicates that the pollution via the concentration in SO2 for example should be included to improve the model.

A growing portion of scientists realises the need to not only alert about climate change, but also change their professional practices. A range of tools have emerged to promote more sustainable activities, yet many scientists struggle to go beyond simple awareness-raising to create concrete transition actions. Here we propose a game-based transition support system MaTerre180’, which has been designed to build scenarios of greenhouse gas (GHG) emission reductions in the academic community. After providing a common scientific background about the context (global warming issue, its causes and consequences) and setting up a challenge (50% reduction of carbon budget by 2030), the participants belonging to the academic community and its governance bodies immerse themselves into fictional characters, to simulate the behaviour of real research groups. The game has been deployed during the year 2021, with six hundred participants from nine countries and 50 cities. Results explore clear pathways for GHG reductions between 25 and 60%, and a median reduction of 46%. The alternatives allowing the greatest reduction are video communication tools (36%), followed by mutualization of professional activities and voluntary cancellation or reduction, that represent 22 and 14% of reduction, respectively. The remaining 28% of reduction consists of transport alternative, relocation of professional activities, extended duration of some travels, etc. In addition, the analyses pointed out the importance of the guided negotiation phase to bring out some alternatives such as relocation, local partners and computing optimization. An added value of this transition support system is that the information it collects (anonymously) will be used to answer pressing research questions in climate change science and environmental psychology regarding the use of serious games for promoting changes in attitudes and behaviours towards sustainability, and including broader questions on how network structures influence “climate behaviour”, knowledge and the governance of the commons. Modestly, MaTerre180’ offers an innovative game-based transition support system to build scenarios of greenhouse gas (GHG) emission reductions in the academic community. It is not simply a question of moving tokens on a virtual gameboard and a playful adjustment of practices, but rather a question of brainstorming about possible and desirable ways of remodelling research and teaching communities and embracing a new paradigm. After tens of workshops, our results show clear pathways for reaching up to 50% GHG reductions and stress the importance of guided negotiations to bring out alternatives to carbonized activities. This first attempt reinforces our belief that scientific engagement is at the heart of the international development agenda and a key approach to tear down the institutional barriers that inhibit the transformation needed to achieve a more sustainable society.

France's monumental heritage has been the subject of little theoretical research in the face of global climate change, although many applied studies have concerned its adaptation and resilience, especially at the local level. Furthermore, this heritage includes more than 44,000 monuments and classified sites, 48 of which being inscribed on the UNESCO List and therefore deserves to be taken into account in the context of the current climate unbalance.The complexity lies in the diversity of materials making up the monuments (stones, glass, metals, wood...) and of phenomena that affect them (as well as other constructions). In order to assess the impact of these increasing slow or extreme events already at work, the tools and methodologies range from the description and inventory of the effects, their measurement, mapping and projection into the future using models such as dose-response functions (DRF) with input data from climate models and scenarios. Ancient data can also be used to complement the correlation between climate and heritage, such as dendroclimatology studies of the wood in monuments.Results from research carried out in France will be presented concerning stone facades, ancient stained glass windows, metals, degradation of walls by salts and dendroclimatology. Further research should focus on the consequences on the monumental heritage of rising marine waters, river and urban flood and low waters, freeze-thaw, the stability of monuments on clay soils and the indoor climate of monuments and their carbon footprint.In conclusion, much remains to be done in France: (1) complete the inventory and description of the phenomena, their impacts and their location at the national, regional, urban and monumental scales, (2) quantify these impacts in the future via empirical or geochemical models based on climate models outputs.

Since the Industrial revolution, emissions of pollutant (gas, aerosols) due to human activities increased and modified the composition of the atmosphere, causing air pollution and climate change. However, pollution measurements are relatively recent. In order to know past air pollution and assess its impact on monuments, proxies need to be found and studied.One of these potential local proxies is black crusts that are a chemical alteration pattern mainly found on limestone or marble monuments. They are forming a dark mineralogical layer composed of gypsum (CaSO4.2H2O) that results from the sulfation reaction between the calcite (CaCO3) of the stone and the sulphur dioxide (SO2) from the atmosphere. As gypsum is easily soluble, this pattern particularly affects sheltered area from the rain where particulate matter is trapped and accumulates. Therefore, black crusts act as passive sampler and could be used as an archive of air pollution.To validate black crusts nomination as a new proxy and to find the best pollution marker, samples were collected at Père Lachaise cemetery on ancient tombs (dated from the 1820’s). A specific protocol was applied to separate strata from each other. Then, multiple analyses were realised using SEM-EDS, ICP-AES, and ICP-MS. The results show a different particulate content as a function of the depth, with different contributions of fly-ash typical of coal and oil combustion. This is confirmed by the chemical analyses as the trace metal concentrations are in agreement with the pollution sources. This study demonstrates that laminar black crusts have an internal stratigraphy that can be crucial to reconstruct past air pollution and provides precious data on pollution sources.

For a long time, limestone has been massively used in stone building and monuments because of its easy extraction and common presence in the landscape. On ancient monuments, mostly built in urban areas, it is exposed to urban-borne pollutants responsible for specific alteration mechanisms and weathering kinetics. Especially, the dissolution of calcite and the precipitation of new phases will affect the limestone pore network, modify the stones capillary properties, and influence the further alteration. In order to better understand these processes, an altered limestone sample from 'Tribunal Administratif' (TA) in Paris was studied. The main secondary phase was found to be syngenite, which can be explained by the location of the sample close to the soil, a potential source of K (fertilizers). This phase is more soluble than gypsum that is commonly found on altered limestone. In order to assess the reactivity of the system (limestone and new phases), oxygen and hydrogen isotopes were used to trace the transfer of water (D218O) and identify the location of the reactive areas (susceptible to alteration). For that, TA samples were exposed in a climatic chamber to relative humidity (RH) cycles (25% RH for 2.5 days and 85% RH for 4.5 days) for 2 months with a D218O vapor to simulate alteration occurring in conditions sheltered from the rain. Results have shown that the water vapor easily circulates deep in the sample and reacts preferentially with syngenite the most reactive phase (compared with calcite and quartz). This phase could evolve in gypsum when exposed to an environment different from the one resulting in its formation.

International audience; The browning phenomenon is a pathology affecting Mn-bearing medieval stained-glass-windows in potash-lime-silicate glass system. In order to unravel the potential implication of microorganisms in the appearance of this pathology, three model glasses respectively containing no MnO, 1wt% and 2wt% MnO were altered at circumneutral pH, with and without organic exudates (oxalic acid (OA) 1000 µM and siderophore desferrioxamine B (DFOB) 50-1000 µM) likely to be produced by bacteria and fungi. In the absence of exudates, the dissolution rates are inversely dependent on the Mn content of the glasses (0.8, 0.5 and 0.4 g m-2 d-1 respectively for no MnO, 1wt% and 2wt% MnO glasses). In contact with exudates, an opposite trend is observed. The prevalent mechanisms are interpreted as a strong ligand-promoted dissolution for DFOB (dissolution rate increase up to 270%) and a dominant proton-promoted dissolution for OA (dissolution rate increase up to 60%). When DFOB and OA are added together, the effect of DFOB on the dissolution rate is prevailing, while OA effect is tangible on the stoichiometry of the dissolution of the alteration. These results suggest that an indirect biological activity could be involved in the mobilization of Mn from a Mn-bearing glass, thus playing a role in the appearance of the browning phenomenon.