Remobilization of bound arsenic and antimony in a flow-through column experiment with peat soil
1University of Oulu, Faculty of Technology, Environmental Engineering
|Online Access:||PDF Full Text (PDF, 5.8 MB)|
|Persistent link:|| http://urn.fi/URN:NBN:fi:oulu-202105207986
Oulu : V. Luostarinen,
|Publish Date:|| 2021-05-20
|Thesis type:||Master's thesis (tech)
Treatment peatlands have been used to purify mine water for years in Finland. In terms of sustainability in mining industry it is important to know what happens to bound contaminants: Do they stay bound or do they start leaching to nature?
This Master Thesis project involved the following research methods: setup and maintenance of flow-through peat columns, sampling inflow, outflow and porewater, analysis of arsenic and antimony using colorimetric methods, dissecting the peat column and determining bound arsenic and antimony concentrations in peat and interpretation of results.
The main hypothesis in this project was: Does reduced arsenic/antimony concentrations in inflow water lead to remobilization and redistribution of the bound contaminants in the peat columns observable as a flattening off and traveling of the peak concentration of bound contaminant. In this thesis the goal was to find out three things: First, is there a clear binding pattern for arsenic and antimony in the peat, i.e., do we see areas with high arsenic/antimony concentrations or is there an even distribution? Second, does remobilization occur when the inflow water quality changes? And last, how does the distribution of arsenic and antimony in the peat column change throughout the remobilization experiment?
The most important finding of this study is that once the inflow water was diluted to low concentration leaching of both arsenic and antimony increased compared to the high concentration of the inflow water. These results also support previous research that there is an increased risk of contaminant leaching after mine closure. These results can be used to get a better understanding how arsenic- and antimony-loaded treatment peatlands should be managed and the risks in leaching even prevented. In general changes in inflow water quality, as may be expected after mine closure, may result in remobilization and subsequent leaching of the bound contaminants.
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