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| Titel |
The effects of wastewater discharge on the microbiological nitrogen cycle of
the lake sediments |
| VerfasserIn |
Jatta Saarenheimo, Sanni L. Aalto, Marja Tiirola |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250134074
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| Publikation (Nr.) |
 EGU/EGU2016-14758.pdf |
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| Zusammenfassung |
| Anthropogenic wastewater inputs alter the natural dynamics of nitrogen (N) cycle by
providing high concentrations of nitrate and organic matter to the sediment microbes. It
can also change the microbial community composition and N removal potential
but this is currently not that well studied. To study these aspects, we conducted
ecosystem-scale experiment in Lake Keurusselkä, Finland. In the experiment, the
wastewater discharge to the recipient lake was optimized with sediment filtration,
which increased the surface and retention time of the nitrified wastewater with the
sediment.
In addition to N transformation rates, which showed that optimization enhanced
denitrification, we studied the microbial responses at the sediment. Genetic potential of
nitrogen transformation processes, such as denitrification, dissimilatory nitrate reduction to
ammonium (DNRA) and nitrification were studied by targeting the functional genes (i.e. nirS,
nirK, nosZI, nosZII, nrfA, amoAarchaea and amoAbacteria) with quantitative PCR and digital
droplet PCR. In addition, changes in the microbial community composition along the
wastewater gradient were examined by using next generation sequencing of the 16S rRNA
genes.
In line with our hypothesis, the relative abundance of denitrifying genes followed
the observed denitrification rates, being highest near the nitrate-rich wastewater
discharge. Furthermore the microbial community composition in the discharge point
differed clearly from the control and downstream sites, having also the highest
numbers of rare OTUs. Abundance of nitrifying bacteria was higher than nitrifying
archaea near the waste water discharge, whereas the opposite was seen at the control
site. The results indicate that wastewater is not only increasing the denitrification
rates, but can also alter the structure and genetic potential microbial communities. |
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