Content of Cu, Mn and Zn in the soils of intensive monitoring stands in northern and central Poland

The paper presents results of the studies on Cu, Mn and Zn content in forest soils of northern and central Poland covered by intensive monitoring. The investigated stands (Białowieża, Chojnów, Gdańsk, Krotoszyn, Krucz, Łąck, Strzałowo, Suwałki) cover various soil reference groups, including Brunic Arenosols, Cambisols and Stagnosols, developed from Quaternary deposits of different origin – glacial till, fluvioglacial sand and aeolian sand over fluvioglacial sand. The soils were sampled from O−horizons and mineral layers from the depths of 0−5, 5−10, 10−20, 20−40 and 40−80 cm. Analysis were performed using standard procedures in soil science and included basic properties (particle−size distribution, pH, organic carbon and total nitrogen), and the contents of Cu, Mn and Zn determined by ICP−OES technique after samples digestion in aqua regia. The noted contents of metals in the soils varied among stands, depending on origin of deposits and their textural parameters. The content of Cu in mineral horizons ranged from 0.0 to 20.0 mg/kg, Mn from 31.0 to 585.0 mg/kg and Zn from 3,6 to 255.0 mg/kg, whereas in O−horizons 3.0−29.1 mg/kg, 86.0−3627.7 mg/kg and 11.0−68.0 mg/kg, respectively. The noted content did not reach geochemical background in most cases, which is typical for forest soils of Poland. It indicates good ecological condition of the studied ecosystems and limited anthropopressure in this range. Vertical variability in the content of Cu, Mn and Zn constituted reflection of soil−forming processes and the influence of vegetation, as a key−factor in element's cycling in forest ecosystems. Strong influence of this factor is confirmed by higher concentration of the studied metals in O−horizon as compared to mineral soil. Moreover, a significant role of lithological discontinuities and water regime have been noted in some stands