2.8 BAPHIM – BAckground and Polluted atmosphere in the HIMalaya. CNR - Institute of Atmospheric Sciences and Climate Principal investigator: Prof. Paolo Bonasoni The background concentration of atmospheric compounds can be investigated at measurement stations sited in high mountain areas. In these regions the chemical physical atmosphere conditions can be strongly affected by short and long range transport of air masses coming from polluted and densely inhabited areas. The aim of the BAPHIM project is to study the atmosphere in the Himalayan area in order to acquire useful information on background composition characterising some atmospheric compounds. This is particularly important for studying climatic change and to define the pollution level of this part of Asiatic continent. This project is based on research frameworks which interact also with other EV-K2-CNR programs. Continuous monitoring will concern the tropospheric ozone and aerosol concentration, while air samplings in flasks and absorption tubes will be carried out in order to evaluate the concentration of 21 halogenated greenhouse gases (CFC-11 ,CFC-12, CFC113, CFC-114, CFC-115, H-1211, H-1301, HCFC-22, HCFC-141b, HCFC-142b, HCFC-124, HFC-125, HCFC-152a, HFC-134a, HFC-143a, C2F6, SF6, CH3Cl, CH3Br, CHCl3, CH2Cl2 ) and volatile organic compounds (VOC). Moreover, measurements of hydrofluorocarbons (Trifluoroacetic acid, TFA) in snow and water basin samples will be performed. The collaboration with other projects (e.g. RATEAP) will permit metals and trace elements to be detected on aerosol samples and radiochemical analysis on aerosol filters to define atmospheric concentration of the cosmogenic radio nuclide Be-7 (the main tracer of stratospheric intrusions). The main natural contribution to the increasing of ozone concentration in free troposphere is due to stratosphere-troposphere exchange processes. During these events stratospheric air rich in O3 and Be-7 can reach the middle and low troposphere. These intrusion phenomena are best identified in very high mountain areas, so that measurements performed in the Himalayan area may significantly contribute to these studies. The verifying and evaluating how this uncontaminated area can be affected by local pollution events or by long range transport of polluted air masses will be an other important aim of the BAPHMON research project. Ozone is not directly emitted in atmosphere by human activities, but is mainly produced by photochemical reaction with anthropogenic pollutants. For this reason it is considered one of the most dangerous pollutants in the low troposphere, because of its high oxidant power and damages which it can cause in the human and vegetal environment. Moreover, the tropospheric ozone production processes are influenced by biogenic emissions of VOC. In these reactions the oxygenated VOC play a key role strongly contributing to tropospheric ozone formation. Due to short lifetime, their presence in the Himalayan area will allow to identify local biogenic sources. The possible presence of non biogenic VOC characterised by a longer lifetime can be due to pollution sources or long range transport of anthropogenic polluted air masses. Aerosol measurements are very important for a better investigation of the pollution problem, because during atmospheric pollution events their chemical – physical properties can significantly change. In fact, the aerosol concentration measure on 15 dimensional channels (0.3 to 20 ?m) will be able to characterise the Himalayan atmosphere, while the analysis (RATEAP collaboration) on the OPC sampled filters will permit to determine the metals and trace elements. Finally, three dimensional back-trajectory analysis will permit to define air mass origins and their contribution to the mean concentration of ozone and other atmospheric compounds. In addition, the project intends to investigate the greenhouse gases in the Himalayan area atmosphere. Among these gases, the ozone present in the middle and high troposphere has great importance, being able to absorb and emit infrared radiation previously emitted from the ground. This is the reason why so many studies are performed to analyse the space and time ozone behaviour also in remote areas. Particularly, measurements and studies on halogenated greenhouse gases is of great importance, because they have a key role in the climate changing. Their origin is mostly anthropogenic and their emissions, even if regulated under International Protocols (Montreal and Kyoto), show a steady increase. Monitoring these chemical species will allow to assess the behaviour of their background concentration at more than 5000 m asl during the next years and also to evaluate the influence of local sources. Hydrofluorocarbons (anthropogenic compounds used as alterative to ozone depleting chlorofluorocarbons) as a consequence of gas phase reaction with OH radicals and other atmospheric components, yield to Trifluoroacetic acid (TFA). The high water solubility of TFA causes its removal from atmosphere by wet deposition via rainfall (following uptake into tropospheric clouds). Long persistence of TFA, due to the lack of sinks for this compound, causes its accumulation in water basins and in soils where it can exploit its phytotoxicity. The possible occurrence of TFA in the different environmental matrices (i.e. snow, fresh water) collected in the Himalayan area will allow to evaluate whether it is only of anthropogenic or also biogenic origin and to estimate the significance of rain for deposition of this compound. Therefore, this project will permit to acquire through “in situ” measurements valuable information on the background concentrations of ozone, aerosol, halogenated greenhouse gases, VOC, TFA and other compounds and to analyze air mass horizontal and vertical transport events affecting their behaviour. Consequently, it will be possible to establish the pollution level and concentration of the main greenhouse gases in a part of atmosphere representative of background condition for a wide area of the Asiatic continent. The research proposal is based on experience gained in several years of measurements at high mountain remote sites like the Mt. Cimone-CNR Station.