9 Mineral particles, mainly windblown dust from local soil: Li, A1, Sc, (V), Cr, Fe, (Co), Ga, Y, La, Sm, Th, U;

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1 ENVIRONMENTAL INDICATORS FOR LONG-RANGE ATMOSPHERIC TRANSPORTED HEAVY METALS BASED ON NATIONAL MOSS SURVEYS TORUNN BERG 1, ULF PEDERSEN l and EILIV STEINS 2 i Norwegian Institute for Air Research, Pb 100, N-2007 Kjeller, Norway; 2 Department of Chemistry, University of Trondheim, AVH, N-7055 Dragvotl, Norway Abstract. Environmental indicators for long-range atmospheric transported heavy metals have been developed. The indicators are based on data for Pb and Cd from national moss surveys which are performed regularly in Norway. The interpolation programme 'kriging' has been used to transform the data from irregular grids to regular grids. Contour maps have been produced, and areas above estimated background levels for Pb and Cd in mosses have been calculated. The indicators are used to characterise the atmospheric deposition of long-range atmospheric transported heavy metals and monitor the changes with time. 1. Introduction Surveys of atmospheric trace element deposition on a geographical basis are performed regularly in Norway (1977, 1985, 1990) by analysis of biomonitor moss (Hylocomium splendens) (Steinnes et al., 1992; Berg et al., 1995a). This is a part of an internordic programme which is performed every 5 year (Riihling et al., 1987), and the programme has recently been extended also to other parts of Europe (Riihling et al., 1992; Riihling, 1994). Because mosses lack a root system they obtain most of their supply of chemical substances directly from precipitation and from the impaction and sedimentation of airborne particles. Mosses also have a very high capacity to retain many metals from solution (Rtihling and Tyler, 1970). Since the carpet of living moss tissue is built up during a period of 3-5 years, the content of metals reflects an integrated measure of the atmospheric deposition during that period. According to results obtained previously (Schaug et al., 1990; Steinnes et al., 1992, 1994; Berg et al., 1995b), elements observed in Hylocomium splendens can be divided in the following way, according to their main sources (elements in parentheses represent a secondary association with the group in question): 9 Long-range atmospheric transport (LRTP) of pollutants from other parts of Europe: V, (Cu), Zn, (Ga), As, Se, Mo, Ag, Cd, Sb, Hg, T1, Pb, Bi; 9 Local point sources of air pollution within or closely outside Norwegian borders: Co, Ni, Cu; 9 Mineral particles, mainly windblown dust from local soil: Li, A1, Sc, (V), Cr, Fe, (Co), Ga, Y, La, Sm, Th, U; Environmental Monitoring and Assessment 43:11-17, (E) 1996 Kluwer Academic Publishers. Printed in the Netherlands.

2 12 TORUNN BERG ETAL. 9 Root uptake in vascular plants from soil, and subsequent transfer to mosses by leaching from living or dead plant material: (Mg), (Ca), Mn, (Cu), (Zn), Rb, (Sr), Cs, Ba; 9 Natural trace element cycling processes, mainly atmospheric transport from the marine environment: (Li), B, Na, Mg, C1, Ca, Se, Br, Sr, I. For those elements with long-range atmospheric transport from other parts of Europe as the main source (V, (Cu), Zn, As, Mo, Cd, Sb, Pb, Bi) it is also possible to convert moss concentration data to absolute deposition rates (Berg et al., 1995b). The moss surveys should therefore be useful as a basis for developing environmental indicators for long-range atmospheric transported heavy metals. The aim of this work is to make a simple tool for the Norwegian environmental authorities to characterise the atmospheric deposition of long-range atmospheric transported heavy metals and monitor the changes with time. 2. Materials and Methods 2.1. SELECTION OF ELEMENTS Respectively 26, 16 and 33 trace elements were determined in the 1977, 1985 and 1990 surveys (Steinnes et al., 1992, 1994; Berg et al., 1995a). In the present work Pb and Cd were chosen as indicator elements because: 9 they have long-range atmospheric transport from other parts of Europe as their main source 9 the uptake in moss is relatively strong 9 it is possible to convert moss concentration data to absolute deposition rates 9 they are very toxic 9 the natural background levels in mosses are very low The major anthropogenic sources of Pb and Cd are different. Pb is mainly spread to the terrestrial environment by combustion of leaded fuel, whereas Cd is spread through emissions from metal industry. Reducing emissions of Pb and Cd require different technologies, which means that emission reductions may have started at different times. It is therefore desirable to study the elements separately. At the moment no protocols exist on reduction of Pb and Cd emissions SAMPLING AND CHEMICAL ANALYSIS Samples ofhylocomium splendens were collected at about 500 sites in 1977, 1985 and The sampling networks were somewhat different for the three moss surveys. While in 1977 a nearly regular network was used, the 1985 and 1990 networks were a little modified according to earlier experience to describe more accurately the situation in the most polluted areas. Analyses were performed by atomic absorption spectroscopy (AAS) using flame (Pb) and graphite furnace (Cd) in 1977 and

3 ENVIRONMENTAL INDICATORS , and by inductively coupled plasma- mass spectrometry (ICP-MS) in Cross checks between data from different years and analytical methodologies were performed by mixing some samples previously analyzed among the new samples. Details from the different surveys including quality assurance procedures are given in Steinnes et al. (1992; 1993; 1994) and Berg et al. (1995a) DATA PROCESSING Moss concentrations of Pb and Cd from about 500 Norwegian sites were interpolated from irregular to regular grids using normal linear kriging (Journel and Huijbregts 1981) for each of the years 1977, 1985, Five samples strongly affected by two local emission sources were excluded before the kriging of Cd data in order to have a data set mainly dominated by long-range transport. Kriging was originally evolved for geostatistical purposes, but has also been used in connection with environmental studies, e.g., long-range atmospheric transported pollutants in Europe (Simpson and Olsen, 1990; Schaug et al., 1991, 1993). The method is based on the assumption that a spatial correlation exists between the measured data, which makes it possible to estimate data values for sites where no data exist. The kriging weights are computed from a variogram, which measures the degree of correlation among sample values in the area as a function of distance and direction of samples. A grid size of 17 x 17 km was used, which is a subdivision of the so-called EMEP-grid (150 x 150 km) into 9 units each way. The kriging procedure is described in detail in e.g., Schaug et al. (1993). Contour maps (Figures 1, 2) were produced using Uniras interpolation routines. Areas (km2and percentage) with different moss concentration levels for Pb and Cd were calculated for those ranges given in the contour maps (Tables I, II). Reference values for Pb and Cd were chosen and areas (km 2 and percentage) with concentration levels above these values were calculated (Table III). 3. Discussion Long-range atmospheric transported elements are characterized by high concentrations in the southernmost part of Norway, rapidly decreasing with increasing distance from the coast. In the development of environmental indicators for these elements, Pb and Cd levels in moss growing in the least polluted areas in Norway were chosen as reference values, and areas with concentrations higher than those values were calculated (Table III). However, the environmental indicators express the changes in atmospheric deposition for the whole country, and not only for the most polluted areas in Norway. Since areas for several concentration ranges were estimated, it is however easy to extract this information from maps and Tables I and II. For Pb 5 ppm was chosen as reference value. Concentrations of Pb in the range 3-5 ppm are normally measured in the least polluted areas of Norway, and the

4 14 TORUNN BERG ETAL. Figure 1. Concentrations of Pb (/,g/g) in moss collected in 1977, 1980, and Figure 2. Concentrations of Cd (/~g/g) in moss collected in 1977, 1980, and analytical results are generally satisfactory in this concentration range. A distinct reduction (ca. 25%) of areas with concentrations above 5 ppm are seen from 1977, 1985 to 1990 (Table III). The 1990 level of lead in moss in the southernmost part of Norway is about 30-40% of what was measured in For Cd 0.1 ppm was chosen as reference value. This value is a little high for background areas, but because of a high detection limit (0.1 ppm) in 1977 and 1985 this was necessary if these parts of the data should be included. The change from

5 ENVIRONMENTAL INDICATORS 15 Table I Areas in Norway (km 2 and %) with different concentration levels of Pb in moss. Estimated values for 1977, 1985 and 1990 Pb in moss Area (km 2) (ppm) Area (%) < > Tot. areas Table II Areas in Norway (km 2 and %) with different concentration levels of Cd in moss. Estimated values for 1977, 1985 and 1990 Cd in moss Area (km z) (ppm) Area (%) < * 58320* " > " Tot. areas * Cd-conc.: <0.1 ppm. use of graphite fumace AAS in 1977 and 1985 to ICP-MS in 1990, resulted in a lower detection limit in 1990 (0.05 ppm). Uncertain values near the detection limit in 1977 and 1985, lead to apparently smaller areas with high values in 1977 than in A distinct reduction (ca. 40%) of areas with concentrations above 0.1 ppm are, however, seen in 1990 compared to 1977 (Table III). The contribution from

6 16 TORUNN BERG ET AL. Table III Areas in Norway (km 2 and %) with concentration levels above the chosen background levels for Pb and Cd in moss. Estimated values for 1977, 1985 and 1990 Indicatore- Area (km 2) Area (%) element Pb: >5 ppm Cd: >0.1 ppm long-range atmospheric transport is reduced in 1990 to about 30-40% of the 1977 level in moss in the southernmost part of the country. The environmental indicators for long-range atmospheric transported heavy metals presented in this work will be updated after the next moss survey which takes place in Acknowledgement The Norwegian State Pollution Control Authority is thanked for financial support. References Berg, T., RCyset, O. and Steinnes, E.: 1995a, 'Atmospheric Trace Element Deposition: Principal Component Analysis of ICP-MS Data from Moss Samples', Environmental Pollution 88, Berg, T., R0yset, O. and Steinnes, E.: 1995b, 'Moss (Hylocomium splendens) Used as Biomonitor of Atmospheric Trace Element Deposition: Estimation of Uptake Efficiencies', Atmospheric Environment 29, Journel, A. G. and Huijbregts, C. J.: 1978, Mining Geostatistics, London, Academic Press. Riihling,,~. and Tyler, G.: 1970, 'Sorption and Retention of Heavy Metals in the Woodland Moss Hylocomium splendens (Hedw.) Br. et Sch', Oikos 21, Riihling,/~., Rasmussen, L., Pilegaard, K., Makinen, A. and Steinnes, E.: 1987, 'Survey of Atmospheric Heavy Metal Deposition in the Nordic Countries in Monitored by Moss Analysis'. Copenhagen, Nordic Council of Ministers (NORD 1987:21). RiJhling,.~., Brumelis, G., Goltsova, N., Kvietkus, K., Kubin, E., Liiv, S., Magnusson, S., M~ikinen, A., Pilegaard, K., Rasmussen, L., Sander, E. and Steinnes, E.: 1992, 'Atmospheric Heavy Metal Deposition in Northern Europe 1990', Copenhagen, Nordic Council of Ministers (NORD 1992:12). Riihling, /~,. (ed.): 1994, 'Atmospheric heavy metal deposition in Europe', Copenhagen, Nordic Council of Ministers (NORD 1994:9). Schaug, J., Pedersen, U. and Skjelmoen, J. E.: 1991, 'Data Report Part I: Annual Summaries', Lillestr0m, NILU: EMEP Chemical Coordinating Centre (EMEP/CCC Report 2/91). Schaug, J., Iversen, T. and Pedersen, U.: 1993, 'Comparison of Measurements and Model Results for Airborne Sulphur and Nitrogen Componenents with Kriging', Atmos. Environ. 27A, Steinnes, E., Ramb~ek, J. P. and Hanssen, J. E.: 1992, 'Large Scale Multi-element Survey of Atmospheric Deposition Using Naturally Growing Moss as Biomonitor', Chemosphere 25,

7 ENVIRONMENTAL INDICATORS 17 Steinnes, E., Johansen, O., ROyset, O. and Odeg~d, M.: 1993, 'Comparison of Different Multielement Techniques for Analysis of Mosses Used as Biomonitors', Environ. Mon. andassessm. 25, Steinnes, E., Hanssen, J. E., Ramb~ek, J. P. and Vogt, N. B.: 1994 'Atmospheric Deposition of Trace Elements in Norway: Temporal and Spatial Trends Studied by Moss Analysis', Water, Air, and Soil Poll. 74,