Search results for "denitrifikaatio"
showing 10 items of 23 documents
Seasonal cycle of benthic denitrification and DNRA in the aphotic coastal zone, northern Baltic Sea
2020
Current knowledge on the seasonality of benthic nitrate reduction pathways in the aphotic, density stratified coastal zone of the Baltic Sea is largely based on data from muddy sediments, neglecting the potential contribution of sandy sediments. To gain a more comprehensive understanding of seasonality in this part of the Baltic Sea coast, we measured rates of benthic denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) monthly in the ice-free period of 2016 in both sandy and muddy aphotic sediments, northwestern Gulf of Finland. No anammox was observed. The seasonal cycle of denitrification in both sediment types was related to the hydrography-driven development …
Methylophaga and Hyphomicrobium can be used as target genera in monitoring saline water methanol-utilizing denitrification.
2016
Abstract Which bacterial taxonomic groups can be used in monitoring saline water methanol-utilizing denitrification and whether nitrate is transformed into N2 in the process are unclear. Therefore, methylotrophic bacterial communities of two efficiently functioning (nitrate/nitrite reduction was 63–96 %) tropical and cool seawater reactors at a public aquarium were investigated with clone library analysis and 454 pyrosequencing of the 16S rRNA genes. Transformation of nitrate into N2 was confirmed using 15N labeling in incubation of carrier material from the tropical reactor. Combining the data with previous study results, Methylophaga and Hyphomicrobium were determined to be suitable targe…
Denitrification and dissimilatory nitrate reduction to ammonium in a lake receiving wastewater effluent
2015
Denitrifikaatio ja DNRA (dissimilatory nitrate reduction to ammonium) ovat nitraattia pelkistäviä prosesseja, jotka yleensä esiintyvät hapettomissa olosuhteissa, kuten järvien sedimenteissä ja alusvesissä. Denitrifikaatiossa syntyy typpikaasua, joka poistuu ilmakehään, kun taas DNRA:n lopputuote on ammonium, joka jää veteen. Luonnollinen denitrifikaatio voi poistaa typpeä jätevedenpuhdistamon poistovedestä, mutta DNRA:n rooli on vähemmän tunnettu. Näiden prosessien tutkiminen voi auttaa jätevedenpuhdistuksen kehittämisessä. Tässä Pro Gradu –työssä tutkittiin denitrifikaation ja DNRA:n prosessinopeuksia sekä nopeuksien korrelaatioita erilaisten vedenlaatumuuttujien kanssa. Tutkimuspaikkana o…
Sediment diffusion method improves wastewater nitrogen removal in the receiving lake sediments
2018
Sediment microbes have a great potential to transform reactive N to harmless N2, thus decreasing wastewater nitrogen load into aquatic ecosystems. Here, we examined if spatial allocation of the wastewater discharge by a specially constructed sediment diffuser pipe system enhanced the microbial nitrate reduction processes. Full-scale experiments were set on two Finnish lake sites, Keuruu and Petäjävesi, and effects on the nitrate removal processes were studied using the stable isotope pairing technique. All nitrate reduction rates followed nitrate concentrations, being highest at the wastewater-influenced sampling points. Complete denitrification with N2 as an end-product was the main nitrat…
Functional gene pyrosequencing reveals core proteobacterial denitrifiers in boreal lakes
2015
Denitrification is an important microbial process in aquatic ecosystems that can reduce the effects of eutrophication. Here, quantification and pyrosequencing of nirS, nirK, and nosZ genes encoding for nitrite and nitrous oxide reductases was performed in sediment samples from four boreal lakes to determine the structure and seasonal stability of denitrifying microbial populations. Sediment quality and nitrate concentrations were linked to the quantity and diversity of denitrification genes, the abundance of denitrifying populations (nirS and nosZ genes) correlated with coupled nitrificationdenitrification (Dn), and the denitrification of the overlying water NO3 − (Dw) correlated with the n…
Denitrifying microbial communities along a boreal stream with varying land-use
2019
Streams have an important role in regulating nitrogen (N) transportation from terrestrial ecosystems to downstream waters. Here, we examined how catchment land-use affects potential denitrification rates and the function and composition of denitrifier communities in boreal stream sediments, using stable isotope incubations and qPCR and 454-pyrosequencing targeted on nirS, nirK and nosZ genes. Although land-use influenced the water chemistry as higher nitrite + nitrate (NO x − ) concentration at the agriculture-affected sampling point, sediment organic matter content was found to be the key factor in regulating potential denitrification rates. However, the abundance as well as the diversity …
Methylophilaceae and Hyphomicrobium as target taxonomic groups in monitoring the function of methanol-fed denitrification biofilters in municipal was…
2017
Abstract Molecular monitoring of bacterial communities can explain and predict the stability of bioprocesses in varying physicochemical conditions. To study methanol-fed denitrification biofilters of municipal wastewater treatment plants, bacterial communities of two full-scale biofilters were compared through fingerprinting and sequencing of the 16S rRNA genes. Additionally, 16S rRNA gene fingerprinting was used for 10-week temporal monitoring of the bacterial community in one of the biofilters. Combining the data with previous study results, the family Methylophilaceae and genus Hyphomicrobium were determined as suitable target groups for monitoring. An increase in the relative abundance …
Microbial Community Response on Wastewater Discharge in Boreal Lake Sediments
2017
Despite high performance, municipal wastewater treatment plants (WWTPs) still discharge significant amounts of organic material and nitrogen and even microbes into the receiving water bodies, altering physico-chemical conditions and microbial functions. In this study, we examined how nitrified wastewater affects the microbiology of boreal lake sediments. Microbial community compositions were assessed with next generation sequencing of the 16S rRNA gene, and a more detailed view on nitrogen transformation processes was gained with qPCR targeting on functional genes (nirS, nirK, nosZI, nosZII, amoAarchaea, and amoAbacteria). In both of the two studied lake sites, the microbial community compo…
Interlake variation and environmental controls of denitrification across different geographical scales
2013
Denitrification in lakes significantly reduces the nitrogen (N) load from land to oceans, but the factors controlling it remain poorly under- stood. Therefore, interlake variation of denitrification in sediments of small to medium-sized lakes (from 0.03 to 17.8 km 2 ) was studied across different geo- graphical scales. At the local scale, the denitrification rates and sediment microbial communities were studied in 4 boreal lakes in close proximity (within 20 km) using the isotope pairing technique (IPT) and molecular methods. These local scale data were com- bined with previously published data on denitrifica- tion rates from 10 other European lakes to extend the analysis to the regional (b…
Keurusselän denitrifikaatioaktiivisuuden ajallinen ja paikallinen vaihtelu
2015
Vesien rehevöityminen on maailmanlaajuinen ongelma. Ihmisen toiminnan takia ravinteita, kuten typpeä ja fosforia, kulkeutuu vesiin paljon aiheuttaen mm. massiivisia leväkukintoja ja happikatoa orgaanisen aineen hajotessa. Tämä vähentää mm. vesien virkistysarvoa sekä kaupallista arvoa. Merissä typpi on rajoittava ravinne ja suurin osa typestä päätyy meriin jokivesien mukana. Järvissä tapahtuvassa denitrifikaatiossa typpi muuttuu kaasumaiseen muotoon, mikä vähentää merien typpikuormaa. Tutkimuksessamme mittasimme denitrifikaationopeutta kolmella eri mittauspisteellä Keuruunselällä vuosien 2013 ja 2014 aikana viitenä kertana. Jaoimme aineiston vuodenajan mukaan kesään, syksyyn ja talveen. Hypo…