University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Avion Anne-Louise Phillips
(2020):
Cadmium Adsorption and Toxicity in a Volcanic Soil Chronosequence from the Galápagos Islands.
Master / Diploma Thesis - Institut für Bodenforschung (IBF),
BOKU-Universität für Bodenkultur,
pp 98.
UB BOKU
obvsg
- Abstract:
- The Galápagos islands are famous the world over and are especially studied for their unique ecology and geology. The soils of the Galapagos, however, have been much less investigated, despite their highly unique characteristics as volcanic soils which develop in a tropical to subtropical climate and so become highly weathered. The volcanic activity in this area has resulted in differently aged islands and this was the basis to set up a soil chronosequence, which consists of six sites all of which are subject to a humid climate, on four islands (Isabela, Floreana, Santa Cruz and San Cristóbal) ranging in age from 1.45 ka to 1070 ka as well as two comparison sites which have a drier climate. The soils in this chronosequence were investigated to determine the changes in their ability to adsorb Cd by determining the Cd adsorption isotherm for each soil. As the soils increased in age, there were many observed changes in their physical and chemical properties. These changes contributed to a decrease in the amount of Cd they were able to adsorb and there was a clear decrease in the steepness of the isotherms with an increase in the age of the soils. Coupled with this, the toxicity effects of Cd on the microbial populations of these soils were also investigated. Microbial activity was measured by observing the response of the CO2-C flux for each soil over two weeks for increasing loading concentrations of Cd. The effect of Cd on microbial community composition was also investigated by analysing the Phospholipid derived fatty acids present in the soil samples at the end of the two weeks. The effect of Cd on the microbial activity was inconclusive, increasing concentrations of Cd were observed to possibly increase the rate at which microbial activity naturally decreased over the investigated time period. The increasing concentrations of Cd only affected the microbial community composition at the fifth site of the chronosequence, by inducing a shift in the bacterial community towards a more gram positive dominated population in soils treated with a higher concentration of Cd.
- Beurteilende(r): Gerzabek Martin