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Nitrogen Cycling at Cold Climate Mine Sites in Northen Sweden
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering. (Applied Geochemistry)ORCID iD: 0000-0002-2720-6442
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

High nitrogen discharge from mining sites has been an environmental issue that has been closely studied in the recent years. The environmental effects of high nitrogen discharge are mainly eutrophication, but can also lead to changed species composition and algae blooms. Nitrogen is a highly abundant element and is the most abundant element in the atmosphere, where 78% by volume is present as dinitrogen (N2 ). Nitrogen is present in reduced form in all organic life as ammonium (NH4 + ). Nitrogen is also present in reduced form as nitrate (NO3 - ) or nitrite (NO2 - ) in most aquatic systems. 

Both nitrate and ammonium is contributing to eutrophication problems worldwide and ammonia (NH3 ) is direct toxic in high concentration to certain sensitive aquatic species. Nitrate in high concentration is also direct toxic, both to humans but also to aquatic biota. 

To trace and quantify different nitrogen transforming processes, their sources and their sinks is called tracing nitrogen cycling and is important due to the environmental effect of nitrogen. Nitrogen is available in many different species and oxidation states which all have their respective geochemistry. This thesis focuses on tracing the complex nitrogen cycle in two different cold climate mining systems in northern Sweden using two different methods. The two studied systems are:

The LKAB underground iron ore mine in Kiruna

Boliden Minerals AB open pit copper ore mine Aitik outside Gällivare 

Two different approaches were used to trace the nitrogen cycling. The LKAB Kiruna mine was investigated using stable nitrogen isotopes. The isotope analysis showed high capability to trace nitrogen cycling, both quantative and qualitative. We also showed the origin of the isotope signals which gives indication to the different sources of nitrogen in the mine. The presented study shows presence of nitrification, ammonium volatilization and ammonium adsorption to waste rock to occur in the water transport system. 

The nitrogen cycling in the Boliden Aitik mine was investigated using a nitrogen model which we developed as part of this thesis. The model is based on Yakushevs Redox Layer model (ROLM). The model contains the state variables ammonium, nitrate, nitrite, plankton, phosphate, dead organic material (both particulate and dissolved) as well as oxygen. The nitrogen concentrations in the Boliden Aitik mine was modeled for the clarification pond and showed, in general, low biological activity. The biological mediated reactions such as nitrification, denitrification, phytoplankton growth and grazing were low in relation to natural lake systems

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2016. , 20 p.
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Keyword [en]
Nitrogen Mining Cycling nutrients Isotopes Nitrogen-model modelling numerical-modelling Isotope-tracing Tracing Isotope geochemistry
National Category
Research subject
Applied Geology
URN: urn:nbn:se:ltu:diva-59661ISBN: 978-91-7583-707-9 (print)ISBN: 978-91-7583-708-6 (electronic)OAI: diva2:1034163
2016-12-06, F341, Luleå Tekniska Universitet, Luleå, 13:00 (English)
VINNOVA, 150 157
Available from: 2016-10-11 Created: 2016-10-11 Last updated: 2016-11-21Bibliographically approved

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