Publications by authors named "Tuula Aarnio"

4 Publications

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The Finnish Baltic Sea Research Programme (BIREME).

Tuula Aarnio

Ambio 2007 Apr;36(2-3):123

Academy of Finland, 00501 Helsinki, Finland.

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April 2007

Nitrification in polluted soil fertilized with fast- and slow-releasing nitrogen: a case study at a refinery landfarming site.

Environ Pollut 2006 Sep 18;143(2):247-53. Epub 2006 Jan 18.

Department of Applied Chemistry and Microbiology, P.O. Box 56, University of Helsinki, FIN-00014 Helsinki, Finland.

The nitrifying activity and the effect of fertilization with urea and methylene urea were studied in a landfarming site. The site has been operative over 20 years and maintained by heavy nitrogen fertilization. The landfarming soil contained 4-6% (w/w) oil. The nitrate accumulation was 20-50mg NO3-N day(-1)kg(-1) observed after methylene urea fertilization of 889 g Nm(-2). Nitrification ex situ (in laboratory conditions) was 8.8 mg NO3-N day(-1) kg(-1) in the presence of 380 mg kg(-1) NH4+-N. The half-saturation concentration of nitrification was more than 200 mg NH4+-N kg(-1). The results show that nitrification was active in soil with high oil concentration. Urea fertilization of 893 g Nm(-2) caused an increase of soil NH4+-N concentration up to 5500 mg kg(-1) and pH>8.5. This led to inhibition of nitrification, which persisted after NH4+ concentration decreased below 200mg NH4+ kg(-1).
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September 2006

Application of cation-exchange membranes for characterisation and imaging ammonia-oxidising bacteria in soils.

FEMS Microbiol Ecol 2005 Aug;53(3):463-72

Department of Biological and Environmental Sciences, Division of General Microbiology, FIN-00014 University of Helsinki, Finland.

A new approach, in which ammonia-oxidizing bacteria (AOB) are entrapped from soil onto cation-exchange membranes, was applied to identify terrestrial AOB by fluorescence in situ hybridization (FISH). An experimental hot spot of ammonia oxidation was developed by establishing a gradient of ammonium substrate (200 to <20 mg NH4+-N l(-1)) diffused through the cation-exchange membranes incubated in soil for 6 months. By this approach we were able to characterise and image indigenous AOB populations growing in heavily oil-polluted soil using FISH and sequence analysis of PCR-amplified 16S rRNA genes, respectively. The FISH results revealed that Nitrosospira-like AOB were dominant on the ammonium-enriched membranes incubated in the soil. Fourteen unique Nitrosospira-like 16S rRNA gene sequences belonging to clusters 2 and 3 were recovered from the soil-incubated membranes and from the soil, suggesting the importance of Nitrosospira-like AOB in the oil-polluted landfarming soil.
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August 2005

Activity, diversity and population size of ammonia-oxidising bacteria in oil-contaminated landfarming soil.

FEMS Microbiol Lett 2005 Sep;250(1):33-8

Department of Ecological and Environmental Sciences, University of Helsinki, Niemenkatu 73, Lahti, Finland.

Chemolithotrophic ammonia-oxidising bacteria (AOB) present in oil-contaminated landfarming soil were studied over two growing seasons in 1999 and 2000. The number of AOB (4-9 x 10(5) cellsg(-1) of dry soil) determined with the quantitative polymerase chain reaction (real-time PCR) and the rate of potential ammonium oxidation (0.05-0.28 microg NO2(-)-N g(-1) of dry soil h(-1)) indicated the presence of stable AOB populations. Denaturing gradient gel electrophoresis (DGGE) profiling and sequence analysis of PCR-amplified AOB 16S rRNA genes showed dominance of Nitrosospira-like sequences in clusters 2 and 3. The present results from the chronically oil-contaminated landfarming soil support the suggested importance of Nitrosospira-like AOB in terrestrial environments.
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September 2005