The information below is summarised from the Witham et al. (2005) paper of similar title. This contains more information on adsorption of species onto ash and sampling and applications of ash-leachates as well as the leachates database. A pdf is available here:
Volcanic ash particles are able to scavenge volatile components of volcanic plumes, resulting in rapid deposition of sulphur, halogens and many other potentially harmful elements. These species may be subsequently leached (e.g., by rainfall), causing heavy loadings to soils and water bodies. The resulting leachate poses a hazard to aquatic, vegetative and soil environments, as well as human health. Several eruptions have resulted in apparent contamination of pasture, sometimes with serious impacts on livestock. Concerns have also been raised over the integrity of drinking-water supplies following tephra fall and have prompted regular sampling of water quality in some active volcanic areas. The main controls on volcanic ash leachate concentrations are summarised below and a database of previous methods used in their sampling and analysis is given. A standard method for sampling volcanic-ash leachates is recommended in the hope that this will enable comparison between future studies.
The processes by which adsorption of volatile elements onto tephra occurs are poorly understood, but some of the main controls are:
The concentrations of the different chemical components measured in ash leachate studies depend not only on these adsorption processes and mechanisms, but also on:
For example, smaller particle size-fractions usually give higher elemental concentrations than larger particles and acid leach treatments generally remove much larger amounts of material from ash than water leaches. All of these controlling factors, except for the conditions following deposition, can be controlled by methodology. Standardisation of results may also be helped by collection of fresh ash immediately following eruption. This will reduce the risk of loss of water-soluble components through subsequent rainfall, although many eruptions will be accompanied by rain.
Leach compositions may also be influenced by partial dissolution of the ash particles, but comparison of the leach constituents to the bulk composition of the ash will help discriminate between species' sources. Additionally, detected leach concentrations of certain elements may be dependent on the presence of other species under certain pH conditions, e.g. Al may reduce F.
The volcanic leachate database (Table 1 in Witham et al. 2005) summarises previous work done on this subject and reports the methods used in each study. As of 2004, over 55 articles reporting original leachate data for 27 volcanoes have been published. These are summarised in the database along with the methods of analysis used in each study. Only those where the method was explicitly given are included in the database. The articles are listed by region of the volcano(es) considered and each database entry contains information on the literature source; eruption (volcano and year); the purpose of the leachate study; the particle size fraction used (if any); the solute used; solute/ash ratio (ml/g); type of agitation used and the time; resting time for the mixture; ions measured in the leachate and the analysis techniques used. Where authors have used more than one analysis method in their study these have been given as separate entries in the database. The remaining studies not included in the database (including Budnikov, 1990; Deger, 1931 and 1932; Hinkley and Smith, 1982; Kirsanov and Yu Ozerov, 1984; Rose, 1977; Rose et al., 1978 and 1982; Rubin et al., 1994; Stoiber et al., 1980 and 1981), report ash leachate analysis results, but exclude details of the methodology. We are aware of some further leachate work, particularly from Japan, but have been unable to find the relevant sources to include in the database. Full references for all the articles included and listed above are given in the reference list. IVHHN invites contributions of further volcanic ash-leachate data, or previously reported measurements that we have overlooked for inclusion in the database.
The database shows that historically leachate studies have been conducted for four main reasons:
The first two reasons are the most common. Over 55 soluble components have been detected in volcanic-ash leachate studies, of which the most commonly analysed are Cl, Ca, Na, SO42-, Mg and F. These are also the elements with the highest concentrations in volcanic-ash water leachates. The elements of most relevance to the environment and to health depend somewhat on the purpose of the investigation, but Al, As, Cl, F, Fe, Hg, Pb and SO42-, are particularly important (Table 1, below). Some elements, including Fe, are important because they increase the surface acidity or reactivity of the ash, which then increases the respiratory hazard associated with the ash. Others are important because of potential deterioration in water quality, including change in pH, and impacts on vegetation. Aluminium is included, because, as well as impacting on health, it counters the biological availability of fluoride.
The database demonstrates the wide variety of analysis techniques used in previous studies. The main inconsistencies in methodology are:
The use of such a wide-range of methods introduces error to direct numerical comparisons between surveys and suggests that a common leachate methodology would be beneficial for future work in this area.
Table 1: Volcanic-ash water-leachate concentration ranges for some of the important health-related ions.
To facilitate comparison between the results of leachate studies, we suggest that the following method should be used in addition to any other variations in method that individual workers might like to implement. (Further explanation of the recommended method is provided below.)
For other techniques used, the full method, particularly the ash to solute ratio, should be stated.
It is important to note that this recommended method is not based on an exhaustive study to find optimal conditions, but rather on the most-used methodologies and findings from previous work. We have suggested a deionised water leach, due to its frequent past use, availability, ease of use in the field, and comparability to drinking water. A mildly acidic leach is more representative of rainwater, particularly in the vicinity of an active eruption, so a repeated analysis of the ash with an acid solution would also be insightful. Acid concentrations used in previous work have varied from 0.1 to 0.0001M (pH 1 - 4) and the leaches have been composed of either nitric acid (HNO3) or hydrochloric acid (HCl). To facilitate analysis of adsorbed Cl-, we recommend the use of nitric acid at a standard solution of 0.001M (pH 3). This level of acidity is in keeping with rainwater pH measured in active volcanic regions. To examine the leaching effects of rainwater in detail, knowledge of the composition of rainwater in the region of interest could be used to make up a suitable proxy solution.
We recommend using the whole ash sample for the leach, as this prevents contamination that might occur when splitting into size fractions. It also gives the most representative value for the total leachate loadings at each site.
The recommended agitation time and lack of resting time is a departure from the approach based on the Taylor and Stoiber (1973) method used by most workers. The ninety-minute combined agitation and contact time was selected based on studies that have examined changing leachate concentrations with time (Frogner et al., 2001; Oskarsson, 1980; Risacher and Alonso, 2001). In all of these, the majority of leaching occurred within the first 60-100 minutes. Studies of mine-waste leachates have also demonstrated that substantial changes in chemistry are possible when samples are left to sit in the leach solution for any length of time following agitation. For rapid appraisal of leachable ions in the field where a health-hazard is feared, agitation can be replaced by quick shaking of the ash-water mixture by hand. This leach solution can then be analysed for the most important ions using ion electrodes. The results will provide a minimum concentration for the leachate loadings and should be followed up by analysis of ash by the complete method.
The unit for reporting leachate results of mg ion/kg ash is recommended as this allows comparison of adsorption between particle sizes, sample sites and volcanoes, and calculation of plume volatile masses where total erupted ash mass is known. If the leach volume is reported, leachate loadings for different sites can be calculated and then extrapolated to wider areas of deposition. This approach assumes that the majority of the leached species are from adsorption and not the bulk ash. For health and environmental studies, reporting concentrations of species in the leach (mg L-1) would also be beneficial and is recommended.
Armienta, M.A., De la Cruz-Renya, S., Morton, O., Cruz, O. and Ceniceros, N., 2002. Chemical variations of tephra-fall deposit leachates for three eruptions from Popocatepetl volcano. Journal of Volcanology and Geothermal Research, 113: 61-80.
Armienta, M.A., Martin - Del Pozzo, A.L., Espinasa, R., Cruz, O., Ceniceros, N., Aguayo, A. and Butron, M.A., 1998. Geochemistry of ash leachates during the 1994-1996 activity of Popocatepetl. Applied Geochemistry, 13(7): 841-850.
Bornemisza, E. and Morales, J.C., 1969. Soil chemical characteristics of recent volcanic ash. Soil Science Society of America Proceedings, 33(4): 528-530.
Budnikov, V.A., 1990. Eruption of Gorelyi volcano in April 1986. Volcanology and Seismology, 10(4): 650-658. Cimino, G. and Toscano, G., 1998. Dissolution of trace metals from lava ash: influence on the composition of rainwater in the Mount Etna volcanic area. Environmental Pollution, 99: 389-393.
Cronin, S.J., Hedley, M.J., Neall, V.E. and Smith, R.G., 1998. Agronomic impact of tephra fallout from the 1995 and 1996 Ruapehu Volcano eruptions, New Zealand. Environmental Geology, 34(1): 21-30.
Cronin, S.J., Hedley, M.J., Smith, R.G. and Neall, V.E., 1997. Impact of Ruapehu ash fall on soil and pasture nutrient status 1. October 1995 eruptions. New Zealand Journal of Agricultural Research, 40: 383-395.
Cronin, S.J., Neall, V.E., Lecointre, J.A., Hedley, M.J. and Loganathan, P., 2003. Environmental hazards of fluoride in volcanic ash: a case study from Ruapehu volcano, New Zealand. Journal of Volcanology and Geothermal Research, 121(3-4): 271-291.
Cronin, S.J. and Sharp, D.S., 2002. Environmental impacts on health from continuous volcanic activity at Yasur (Tanna) and Ambrym, Vanuatu. International Journal of Environmental Health Research, 12: 109-123.
de Hoog, J.C.M., Koetsier, G.W., Bronto, S., Sriwana, T. and van Bergen, M.J., 2001. Sulfur and chlorine degassing from primitive arc magmas: temporal changes during the 1982-1983 eruptions of Galunggung (West Java, Indonesia). Journal of Volcanology and Geothermal Research, 108: 55-83.
Dahlgren, R.A., Ugolini, F.C. and Casey, W.H., 1999. Field weathering rates of Mt. St. Helens tephra. Geochimica et Cosmochimica Acta, 63(5): 587-598.
Deger, E., 1931. Chemische Untersuchung der bei den Ausbruchen des Vulkans Santa-Maria, Guatemala, im Jahre 1929 niedergegangenen Auswurfsmaterialien. Chemie Der Erde, 6(3): 376-380.
Deger, E., 1932. Der Ausbruch des Vulkans "Fuego" in Guatemala am 21 Januar 1932 und die chemische Zusammensetzung seiner Auswurfsmaterialien. Chemie Der Erde, 7(2): 291-297.
Dethier, D.P., Pevear, D.R. and Frank, D., 1981. Alteration of new volcanic deposits. In: P.W. Lipman and D.R. Mullineaux (Editors), The 1980 eruptions of Mount St. Helens, Washington. USGS Professional Paper, pp. 649-665.
Edmonds, M., Oppenheimer, C., Pyle, D.M. and Herd, R.A., 2003. Rainwater and ash leachate analysis as proxies for plume chemistry at Soufriere Hills Volcano, Montserrat. In: C. Oppenheimer, D.M. Pyle and J. Barclay (Editors), Volcanic Degassing. Geological Society, London.
Frogner, P., Gislason, S.R. and Oskarsson, N., 2001. Fertilizing potential of volcanic ash in ocean surface water. Geology, 29(6): 487-490.
Fruchter, J.S., Robertson, D.E., Evans, J.C., Olsen, K.B., Lepel, E.A., Laul, J.C., Abel, K.H., Sanders, R.W., Jackson, P.O., Wogman, N.S., Perkins, R.W., Van Tuyl, H.H., Beauchamp, R.H., Shade, J.W., Daniel, J.L., Erikson, R.L., Sehmel, G.A., Lee, R.N., Robinson, A.V., Moss, O.R., Briant, J.K. and Cannon, W.C., 1980. Mount St. Helens ash from the 18 May 1980 eruption: chemical, physical, mineralogical, and biological properties. Science, 209(4461): 1116-1125.
Giggenbach, W.F., 1989. Lonquimay, Scientific Event Alert Network (SEAN) Bulletin, v. 14. no. 7, Smithsonian Institution.
Gough, L.P., Severson, R.C., Lichte, F.E., Peard, J.L., Tuttle, M.L., Papp, C.S.E., Harms, T.F. and Smith, K.S., 1981. Ash-fall effects on the chemistry fo wheat and the Ritzville soil series, eastern Washington. In: P.W. Lipman and D.R. Mullineaux (Editors), The 1980 eruptions of Mount St. Helens, Washington. USGS Professional Paper, pp. 761-782.
Hinkley, T., Lichte, F.E., Taylor, H.E. and Smith, K.S., 1980. Conmposition of ash and its leachates from Mount St. Helens. Abstracts with Programs - Geological Society of America, 12(7): 447.
Hinkley, T. and Smith, K.S., 1982. Leachate chemistry of the tephra from the May 18 1980 eruption of Mount St. Helens. EOS, Transactions, American Geophysical Union, 63(45): 1143.
Horwell, C.J., Fenoglio, I., Ragnarsdottir, K.V., Sparks, R.S.J. and Fubini, B., 2003. Surface reactivity of volcanic ash from the eruption of Soufrière Hills volcano, Montserrat, West Indies with implications for health hazards. Environmental Research: 93: 202-215.
Ivanov, B.V., Flerov, G.B., Masurenkov, Y.P., Kiriyanov, V.Y., Melekestsev, I.V., Taran, Y.A. and Ovsyannikov, A.A., 1996. The 1991 eruption of Avacha Volcano: dynamics and composition of eruptive products. Volcanology and Seismology, 17(4-5): 369-394.
Kawaratani, R.K. and Fujita, S.-I., 1990. Wet deposition of volcanic gases and ash in the vicinity of Mount Sakurajima. Atmospheric Environment, 24A(6): 1487-1492.
Kirsanov, I.T. and Yu Ozerov, A., 1984. Composition of products and energy yield of the 1980-1981 Gorelyi Volcano eruption. Volcanology and Seismology, 5(1): 23-43.
McKnight, D.M., Feder, G.L. and Stiles, E.A., 1981a. Effects on a blue-green alga of leachates of ash from the May 18 eruption. In: P.W. Lipman and D.R. Mullineaux (Editors), The 1980 eruptions of Mount St. Helens, Washington. USGS Professional Paper, pp. 733-741.
McKnight, D.M., Feder, G.L. and Stiles, E.A., 1981b. Toxicity of volcanic-ash leachate to a blue-green alga. Results of a preliminary bioassay experiment. Environmental Science and Technology, 15(3): 362-364.
Murata, K.J., Dondoli, C. and Saenz, R., 1966. The 1963-65 eruption of Irazu volcano, Costa Rica (the period of March 1963 to October 1964). Bulletin Volcanologique, 29: 765-796.
Nehring, N.L. and Johnston, D.A., 1981. Use of ash leachates to monitor gas emissions. In: P.W. Lipman and D.R. Mullineaux (Editors), The 1980 eruptions of Mount St. Helens, Washington. USGS Professional Paper, pp. 251-254.
Nogami, K., Hirabayashi, J., Ohba, T. and Yoshiike, Y., 2000. The 1997 phreatic eruption of Akita-Yakeyama volcano, northeast Japan: Insight into the hydrothermal processes. Earth and Planetary Science Letters, 52: 229-236.
Oskarsson, N., 1980. The interaction between volcanic gases and tephra: fluorine adhering to tephra of the 1970 Hekla eruption. Journal of Volcanology and Geothermal Research, 8: 251-266.
Risacher, F. and Alonso, H., 2001. Geochemistry of ash leachates from the 1993 Lascar eruption, northern Chile. Implication for recycling of ancient evaporites. Journal of Volcanology and Geothermal Research, 109(4): 319-337.
Rose Jr., W.I., 1977. Scavenging of volcanic aerosol by ash: atmospheric and volcanologic implications. Geology, 5: 621-624.
Rose Jr., W.I., Anderson Jr., A.T., Woodruff, L.G. and Bonis, S.A., 1978. The October 1974 basaltic tephra from Fuego volcano: description and history of the magma body. Journal of Volcanology and Geothermal Research, 4: 3-53.
Rose Jr., W.I., Bonis, S., Stoiber, R.E., Keller, M. and Bickford, T., 1973. Studies of volcanic ash from two recent Central American eruptions. Bulletin Volcanologique, 37(3): 338-364.
Rose Jr., W.I., Stoiber, R.E. and Malinconico, L.L., 1982. Eruptive gas compositions and fluxes of explosive volcanoes: budget of S and Cl emitted from Fuego volcano, Guatemala. In: R.S. Thorpe (Editor), Andesites: Orogenic Andesites and Related Rocks. John Wiley & Sons, Chichester, pp. 669-676.
Rubin, C.H., Noji, E.K., Seligman, P.J., Holtz, J.L., Grande, J. and Vittani, F., 1994. Evaluating a fluorosis hazard after a volcanic eruption. Archives of Environmental Health, 49(5): 395-401.
Smith, D.B., Zielinski, R.A. and Rose Jr., W.I., 1982. Leachability of uranium and other elements from freshly erupted volcanic ash. Journal of Volcanology and Geothermal Research, 13(1-30).
Smith, D.B., Zielinski, R.A., Taylor, H.E. and Sawyer, M.B., 1983. Leaching characteristics of ash from the May 18, 1980, eruption of Mount St. Helens volcano, Washington. Bulletin Volcanologique, 46(2): 103-124.
Stoiber, R.E., Williams, S.N. and Malinconico, L.L., 1980. Mount St. Helens, Washington, 1980 volcanic eruption: magmatic gas component during the first 16 days. Science, 208: 1258-1259.
Stoiber, R.E., Williams, S.N., Malinconico, L.L., Jr., Johnston, D.A. and Casadevall, T.J., 1981. Mt. St. Helens: evidence of increased magmatic gas component. Journal of Volcanology and Geothermal Research, 11: 203-212.
Taylor, H.E. and Lichte, F.E., 1980. Chemical composition of Mount St. Helens volcanic ash. Geophysical Research Letters, 7(11): 949-952.
Taylor, P.S. and Stoiber, R.E., 1973. Soluble material on ash from active Central American volcanoes. Geological Society of America Bulletin, 84(3): 1031-1042.
Tovarova, I.I., 1958. Removal of water-soluble substances from the pyroclastic rocks of the volcano Bezymyannyi. Geochemistry: A translation of Geokhimia, 7: 856-860.
Varekamp, J.C., Luhr, J.F. and Prestegaard, K.L., 1984. The 1982 eruptions of El Chichon Volcano (Chiapas, Mexico): character of the eruptions, ash-fall deposits, and gasphase. Journal of Volcanology and Geothermal Research, 23: 39-68.
Viramonte, J., 1987. Lascar, Scientific Event Alert Network (SEAN) Bulletin, v. 12, no. 5, Smithsonian Institution. WHO, 1993. Guidelines for Drinking-Water Quality, 2nd edition. World Health Organisation, Geneva.
Williams, S.N., Stoiber, R.E., Garcia, N., Londono, A., Gemmell, B., Lowe, D.R. and Connor, C.B., 1986. Eruption of the Nevado del Ruiz volcano, Colombia, on 13 November 1985: gas flux and fluid geochemistry. Science, 233: 964-967.
Witham, C.S., Oppenheimer, C. and Horwell, C.J., 2005, Volcanic ash-leachates: a review and recommendations for sampling methods. Journal of Volcanology and Geothermal Research, doi:10.1016/j.jvolgeores.2004.11.010
Download our pamphlets on preparing for ashfall and on the health hazards of ash. They are designed for mass distribution at the onset of new eruptions. They are now avaiable in English, Japanese, French Spanish, Portuguese, Swahili, Indonesian and Icelandic with Italian versions being available shortly. Please see our Pamphlets page for further infomation.
FACE MASK USE
IVHHN has an article under the Guidelines tab which used to be called 'Recommended Face Masks'. This has now been updated to 'Information on face masks' and is an interim page whilst the Health Interventions in Volcanic Eruptions project investigates which types of respiratory protection are effective in protecting the general population from volcanic ash inhalation. Please note that the translations in Spanish, Japanese and Portuguese have not yet been updated.