Atmospheric Measurement Techniques Discussions www.atmos-meas-tech-discuss.net 1867-8610 2 1 2009 10.5194/amtd-2-237-2009 http://www.atmos-meas-tech-discuss.net/2/237/2009/ http://www.atmos-meas-tech-discuss.net/2/237/2009/amtd-2-237-2009.html http://www.atmos-meas-tech-discuss.net/2/237/2009/amtd-2-237-2009.pdf 237 264 2009-02-04 Determination of water-insoluble light absorbing matter in rainwater using polycarbonate membrane filters and photometric detection J. E. Engström erik.engstrom@misu.su.se C. Leck Department of Meteorology, Arrhenius Laboratory, Stockholm Univ., 10691 Stockholm, Sweden A method for determination of water-insoluble light absorbing matter in rainwater has been developed. After collection the rainwater samples were filtered using polycarbonate membrane filter in the laboratory. After drying the filter in filtered air, the amount of water-insoluble light absorbing matter (soot) on the filters was determined with photometry at a wavelength of 555 nm. The precision for the method was better than 10% calculated as relative standard deviation. The overall loss of soot due to adsorption during collection and filtration was 22±2%. The detection limit was estimated to 0.025 in optical density, or 2 ng/ml expressed as a concentration assuming a filtration volume of 30 ml. Analysis of environmental samples have been successfully performed with the described method at the Maldives Climate Observatory Hanimaadhoo and Nepal Climate Observatory. At Maldives the average soot concentration in rain was 0.048 μg/ml and at the Nepal obseravtory 0.086 μg/ml. Bond, T., Theodore, L., Anderson, T., and Campbell, D.: Calibration and intercomparison of filter-based measurements of visible light absorption by aerosols, Aerosol Sci. Tech., 30, 582–600, 1999. Heintzenberg, J.: A Processor-Controlled Multisample Soot Photometer, Aerosol Sci. Tech., 8, 227–233, 1988. IPCC: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 996 pp., 2007. Kopp, C., Petzold, A., and Niessner, R.: Investigation of the specific attenuation cross-section of aerosols deposited on fiber filters with a polar photometer to determine black carbon, J. Aerosol Sci., 30, 1153–1163, 1999. Ogren, J. and Charlson: Wet deposition of elemental carbon and sulfate in Sweden, Tellus B, 36, 262–271, 1984. Ogren, J., Charlson, R., and Groblicki, P.: Determination of elemental carbon in rainwater, Anal. Chem., 55, 1569–1572, 1983. Ogren, J A. and Charlson, R J.: Elemental carbon in the atmosphere: cycle and lifetime, Tellus, 35B, 241–254, 1983. Ogren, J A., Groblickl, P J., and Charlson, R J.: Measurement of the removal rate of elemental carbon from the atmosphere, Sci. Total Environ., 36, 329–338, 1984. Petzold, A., Schloesser, H., Sheridan, P J., Arnott, W P., Ogren, J A., and Virkkula, A.: Evaluation of multiangle absorption photometry for measuring aerosol light absorption, Aerosol Sci. Tech., 39, 40–51, 2005. Ramanathan, V., Crutzen, P., Kiehl, J T., and Rosenfeld, D.: Aerosols, Climate and the Hydrological Cycle, Science, 294, 2119–2124, 2001. Ramanathan, V., Chung, C., Kim, D., Bettge, T., Buja, L., Kiehl, J., Washington, W M., Fu, Q., and Sikka, D R.: Atmospheric brown clouds: Impacts on South Asian climate and hydrological cycle, Proceedings of the National Academy of Sciences of The United States of America, 2005. WHO: Health risks of particulate matter from long-range transboundary air 15 pollution, WHO Regional Office for Europe, 2006.