Heavy metal pollution and mineralisation of nitrogen in forest soils

Abstract

LITTER decomposition and soil enzymatic activity in forests surrounding metal-processing industries are influenced by high concentrations of deposited heavy metals1–2. Very little seems to be known about the effects of heavy metal pollution on nitrogen mineralisation rates in natural soils. Reports on nitrogen mineralisation and nitrification rates after addition of heavy metal salts to mineral soils are not quite unanimous3–6. There is evidence, however, that the ammonification rate of some vineyard soils is retarded by accumulated Cu7. I have determined the relationship between nitrogen mineralisation rate and the degree of Cu and Zn pollution in conifer forest soils, and found that soil nitrogen mineralisation is impaired by industrial metal pollution. I also conclude that a Cu and Zn concentration of three times the background level is sufficient to bring about a measurable disturbance of the nitrogen mineralisation rate.