Influence of lead on organisms within the detritus food web of a contaminated pine forest soil

The shooting range site at Halvala in southern Finland is heavily contaminated by lead pellets. Still, the appearance of the forest is not visibly changed. Lead contamination strongly decreased the amount of enchytraeid worms, while reporter bacteria showed no or very minor decrease in viability. The bioavailability of lead in the soil was measured to be low, which was verified by the very low water extractability of lead. Nevertheless, the frequency of lead resistant cultivable bacteria was elevated, and the bacterial community composition in lead contaminated soil was altered. Some enzymes of litter decomposing fungi isolated from Halvala also showed an elevated lead tolerance, though generally their activity was highly variable and in some cases lead enhanced enzyme production of a fungus. In conclusion, our results point to a low acute toxicity of lead, but to a risk of deleterious long term effects in a pine forest environment.