University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Doctoral Thesis:
Georg Johann Lair
(2006):
Sorption of Copper, Cadmium and Zinc to soil influenced by different soil management in long-term field experiments.
Doctoral Thesis,
BOKU-Universität für Bodenkultur,
pp 92.
UB BOKU
obvsg
- Abstract:
- The present study investigates the impact of long-term soil management on the metal retention capacity of soil. The sorption behaviour of Cu, Cd and Zn was examined in soils and in the various particle size fractions of these soils, which had been treated differently over years. Soils were collected from two long-term field experiments, located in Gumpenstein (Austria) and Ultuna (Sweden). Soils contained varying amounts and origins of organic matter (OM) and differed in soil pH, whereas the mineral phase showed little response to the different soil management. Ad- and desorption isotherms were gained from batch sorption experiments adding high metal loadings and were described by Freundlich equations. Sorption isotherms revealed enhanced metal retention with increasing soil pH and OM content. In the Ultuna soils, sorption increased among the investigated farming practices in the following order: sewage sludge <= fallow < inorganic fertiliser < without N = green manure < peat < Ca(NO3)2 < animal manure <= grassland/extensive pasture. Amounts of retained Cu, Cd and Zn differed by a factor of almost 2.5 among the soils in the Ultuna long-term field experiment and by a factor of 3 among Gumpenstein soils, when the highest concentration of metal was added to soil. Simple mathematical equations obtained from linear regressions were used to estimate the Freundlich parameters KF and n values of the sorption isotherms. Equations exhibited the important role of soil pH, soil organic carbon, especially of the carboxyl and carbonyl carbon, and the dissolved organic carbon for the sorption of heavy metals. Mineral surfaces and OC showed no additive behaviour on heavy metal sorption. Physical structure of the soil organic matter and interactions with the soil mineral phase seemed to influence the sorption capacity of the soils. An increased sorption on smaller particle size fractions occurred (clay >> silt > fine sand >= coarse sand) due to the higher surface area as well as the higher carbon content in the smaller fractions. A sequential extraction procedure yielded comprehensive insights into the distribution of selected metals among operationally defined fractions in both the original and metal-spiked soil. Recently added Cu, Cd and Zn-ions were present mainly on soil particle surfaces as more mobile fractions. In contrast, metals in original soils were recognized in more immobile fractions, reflecting their long-term sorption behaviour.