Environmental Geoi’Hysics In Finland: State Of The Art

Soil and groundwater contamination has become one of the foremost environmental problems in all industrialized<br>countries. A recent survey in Finland resulted in a national soil-hazard database of about ten thousand suspect sites.<br>Although the most problematic sites have been identified, international experiences indicate that further contaminated sites<br>are likely to be revealed. The biggest groups of problem sites are sawmills and wood impregnation factories, landfills,<br>scrap-metal and repair shops and gasoline stations, which in total make more than half of the known problem sites. Over<br>2,000 hazardous sites are located in groundwater reservoir areas, and the most urgent need for remediation is estimated to<br>involve at least 250 sites with remediation costs totalling US.% 1.3 billion. Although adequate legislation is in effect for<br>currently existing operators, the hostless and abandoned, contaminated soil sites remain as an unsolved problem.<br>The most widely applied geophysical techniques in this context in Finland are the seismic refraction method, ground<br>penetrating radar and earth resistivity/conductivity measurements. Depending on the type of survey problem at hand, even<br>gravity and magnetic methods can provide useful information. In terms of specific survey problems, the scope of<br>geophysical techniques has seen a remarkable widening in the last ten years. Of special importance in Finland are the<br>nuclear waste repository investigations, which have given rise to new survey methods, instrumentation and data<br>interpretation. The synergistic benefits to environmental surveys from new contributions in mining geophysics should not<br>be underestimated either. In Finland good examples of this synergy are the spectral induced polarization method, the EM<br>frequency-sounding method, and an operational method (since early 1980’s) for the measurement of snow-water equivalent<br>for water reservoir optimization. Currently small but challenging fields of geophysical application are archaeological<br>surveys and sea-ice thickness determinations with airborne EM techniques, both of which show good promise of increased<br>importance in the near future.