32 research outputs found
GIS-basierte Analyse von Nachnutzungsstrategien fĂŒr Biogasanlagen zur Erzeugung von grĂŒnem Wasserstoff in Niedersachsen
FĂŒr ĂŒber ein Drittel der niedersĂ€chsischen Biogasanlagen lĂ€uft in den nĂ€chsten fĂŒnf Jahren die Förderung nach dem Erneuerbare-Energien-Gesetz aus. Damit droht einem GroĂteil dieser Anlagen aus ökonomischen GrĂŒnden die Stilllegung. Ziel dieser Arbeit ist die Entwicklung einer Nachnutzungsstrategie fĂŒr diese Biogasanlagen zur Erzeugung von Wasserstoff und Methan aus erneuerbaren Energien. In einem ersten Schritt wird diese Nachnutzungsstrategie im Rahmen einer Fallstudie anhand zweier Biogasanlagen erarbeitet. In einem zweiten Schritt werden die Ergebnisse der Fallstudie abgeleitet, um die Nachnutzungsstragie auf sĂ€mtliche niedersĂ€chsischen Biogasanlagen zu ĂŒbertragen und das Methanisierungspotenzial fĂŒr ganz Niedersachsen zu ermitteln.
Methodisch wird dazu die Biogasanlage um eine Power-to-Gas-Prozesskette zur Erzeugung und Einspeisung von grĂŒnem Wasserstoff und Methan erweitert und anhand des CO2-Volumenstroms der Biogasanlage ausgelegt. Als wichtige Voraussetzung fĂŒr die Wirtschaftlichkeit gilt die VerfĂŒgbarkeit von erneuerbaren Energien, weshalb neben einer Wirtschaftlichkeitsberechnung eine GIS-basierte Analyse zur Identifizierung von PotenzialflĂ€chen fĂŒr Windenergie- und FreiflĂ€chen-Photovoltaikanlagen durchgefĂŒhrt wird. Auf Grundlage eines Biogasanlagen-Katasters und einer landesweiten PotenzialflĂ€chenanalyse wird mit Hilfe eines GIS das Methanisierungspotenzial fĂŒr ganz Niedersachsen berechnet.
Synergien bei der Kopplung von Biogasanlagen mit einer biologischen ex-situ Methanisierung (Power-to-Gas-Anlage) hinsichtlich der ProzessfĂŒhrung und -technik sowie wirtschaftlicher Parameter konnten im Rahmen der Auslegung aufgezeigt werden. Trotz der VerfĂŒgbarkeit gĂŒnstigen erneuerbaren Stroms ist die Power-to-Gas-Anlage nur unter gewissen regulatorischen Voraussetzungen wirtschaftlich zu betreiben.
Durch die niedersachsenweite Analyse aller Biogasanlagen ab einer GröĂe von 250 kW konnte aufgezeigt werden, dass weder die Distanz zu dem Gasnetz noch die VerfĂŒgbarkeit von PotenzialflĂ€chen fĂŒr erneuerbare Energien einen limitierenden Faktor fĂŒr die Methanisierung darstellen. Daraus ergibt sich ein signifikantes Potenzial der dezentralen Methanisierung in Niedersachsen durch die Kopplung mit Biogasanlagen von ca. 1.397 Mio. Kubikmeter Methan jĂ€hrlich
Anaerobic ammonium-oxidising bacteria: A biological source of the bacteriohopanetetrol stereoisomer in marine sediments
Bacterially-derived bacteriohopanepolyols (BHPs) are abundant, well preserved lipids in modern and paleo-environments. Bacteriohopanetetrol (BHT) is a ubiquitously produced BHP while its less common stereoisomer (BHT isomer) has previously been associated with anoxic environments; however, its biological source remained unknown. We investigated the occurrence of BHPs in Golfo Dulce, an anoxic marine fjord-like enclosure located in Costa Rica. The distribution of BHT isomer in four sediment cores and a surface sediment transect closely followed the distribution of ladderane fatty acids, unique biomarkers for bacteria performing anaerobic ammonium oxidation (anammox). This suggests that BHT isomer and ladderane lipids likely shared the same biological source in Golfo Dulce. This was supported by examining the BHP lipid compositions of two enrichment cultures of a marine anammox species ('. Candidatus Scalindua profunda'), which were found to contain both BHT and BHT isomer. Remarkably, the BHT isomer was present in higher relative abundance than BHT. However, a non-marine anammox enrichment contained only BHT, which explains the infrequence of BHT isomer observations in terrestrial settings, and indicates that marine anammox bacteria are likely responsible for at least part of the environmentally-observed marine BHT isomer occurrences. Given the substantially greater residence time of BHPs in sediments, compared to ladderanes, BHT isomer is a potential biomarker for past anammox activity
Microbial diversity in waters, sediments and microbial mats evaluated using fatty acid-based methods
The review summarises recent advances towards a greater comprehensive assessment of microbial diversity in aquatic environments using the fatty acid methyl esters and phospholipid fatty acids approaches. These methods are commonly used in microbial ecology because they do not require the culturing of micro-organisms, are quantitative and reproducible and provide valuable information regarding the structure of entire microbial communities. Because some fatty acids are associated with taxonomic and functional groups of micro-organisms, they allow particular groups of micro-organisms to be distinguished. The integration of fatty acid-based methods with stable isotopes, RNA and DNA analyses enhances our knowledge of the role of micro-organisms in global nutrient cycles, functional activity and phylogenetic lineages within microbial communities. Additionally, the analysis of fatty acid profiles enables the shifts in the microbial diversity in pristine and contaminated environments to be monitored. The main objective of this review is to present the use of lipid-based approaches for the characterisation of microbial communities in water columns, sediments and biomats
Biomarkers in the stratified water column of the Landsort Deep (Baltic Sea)
The water column of the Landsort Deep, central
Baltic Sea, is stratified into an oxic, suboxic, and anoxic
zone. This stratification controls the distributions of individual
microbial communities and biogeochemical processes.
In summer 2011, particulate organic matter was filtered
from these zones using an in situ pump. Lipid biomarkers
were extracted from the filters to establish water-column
profiles of individual hydrocarbons, alcohols, phospholipid
fatty acids, and bacteriohopanepolyols (BHPs). As a reference,
a cyanobacterial bloom sampled in summer 2012
in the central Baltic Sea Gotland Deep was analyzed for
BHPs. The biomarker data from the surface layer of the oxic
zone showed major inputs from cyanobacteria, dinoflagellates,
and ciliates, while the underlying cold winter water
layer was characterized by a low diversity and abundance
of organisms, with copepods as a major group. The suboxic
zone supported bacterivorous ciliates, type I aerobic methanotrophic
bacteria, sulfate-reducing bacteria, and, most likely,
methanogenic archaea. In the anoxic zone, sulfate reducers
and archaea were the dominating microorganisms as indicated
by the presence of distinctive branched fatty acids:
archaeol and pentamethylicosane (PMI) derivatives, respectively.
Our study of in situ biomarkers in the Landsort Deep
thus provided an integrated insight into the distribution of relevant
compounds and describes useful tracers to reconstruct
stratified water columns in the geological record.Open Access Publikationsfonds 201
Bacteriohopanepolyols record stratification, nitrogen fixation and other biogeochemical perturbations in Holocene sediments of the central Baltic Sea
The Baltic Sea, one of the world's largest brackish-marine basins, established after deglaciation of Scandinavia about 17 000 to 15 000 yr ago. In the changeable history of the Baltic Sea, the initial freshwater system was connected to the North Sea about 8000 yr ago and the modern brackish-marine setting (Littorina Sea) was established. Today, a relatively stable stratification has developed in the water column of the deep basins due to salinity differences. Stratification is only occasionally interrupted by mixing events, and it controls nutrient availability and growth of specifically adapted microorganisms and algae. We studied bacteriohopanepolyols (BHPs), lipids of specific bacterial groups, in a sediment core from the central Baltic Sea (Gotland Deep) and found considerable differences between the distinct stages of the Baltic Sea's history. Some individual BHP structures indicate contributions from as yet unknown redoxcline-specific bacteria (bacteriohopanetetrol isomer), methanotrophic bacteria (35-aminobacteriohopanetetrol), cyanobacteria (bacteriohopanetetrol cyclitol ether isomer) and from soil bacteria (adenosylhopane) through allochthonous input after the Littorina transgression, whereas the origin of other BHPs in the core has still to be identified. Notably high BHP abundances were observed in the deposits of the brackish-marine Littorina phase, particularly in laminated sediment layers. Because these sediments record periods of stable water column stratification, bacteria specifically adapted to these conditions may account for the high portions of BHPs. An additional and/or accompanying source may be nitrogen-fixing (cyano)bacteria, which is indicated by a positive correlation of BHP abundances with C<sub>org</sub> and δ<sup>15</sup>N
Aerobic methanotrophy within the pelagic redox-zone of the Gotland Deep (central Baltic Sea)
Water column samples taken in summer 2008 from
the stratified Gotland Deep (central Baltic Sea) showed a
strong gradient in dissolved methane concentrations from
high values in the saline deep water (max. 504 nM) to low
concentrations in the less dense, brackish surface water
(about 4 nM). The steep methane-gradient (between 115 and
135 m water depth) within the redox-zone, which separates
the anoxic deep part from the oxygenated surface water
(oxygen concentration 0â0.8 mL L
â
1
), implies a methane
consumption rate of 0.28 nM d
â
1
. The process of micro-
bial methane oxidation within this zone was evident by a
shift of the stable carbon isotope ratio of methane between
the bottom water (
ÎŽ
13
C CH
4
=â
82.4 â°) and the redox-
zone (
ÎŽ
13
C CH
4
=â
38.7 â°). Water column samples be-
tween 80 and 119 m were studied to identify the microor-
ganisms responsible for the methane turnover in that depth
interval. Notably, methane monooxygenase gene expression
analyses for water depths covering the whole redox-zone
demonstrated that accordant methanotrophic activity was
probably due to only one phylotype of the aerobic type I
methanotrophic bacteria. An imprint of these organisms on
the particular organic matter was revealed by distinctive
lipid biomarkers showing bacteriohopanepolyols and lipid
fatty acids characteristic for aerobic type I methanotrophs
(e.g., 35-aminobacteriohopane-30,31,32,33,34-pentol), cor-
roborating their role in aerobic methane oxidation in the
redox-zone of the central Baltic Sea
The influence of bacterial activity on phosphorite formation in the Miocene Monterey Formation, California
Authigenic phosphorites from the Miocene Monterey Formation (California) including an autochthonous phosphatic laminite were analyzed for molecular biomarkers, element content, and sulfur isotopic composition of associated pyrite and sulfate to evaluate the role of bacterial activity in the precipitation of phosphate minerals. The phosphorites formed in a depositional environment typified by upwelling with dynamic bottom currents and hardground formation. Pyrite enclosed in the phosphorites shows ÎŽ34S values as low as â 36.5â° VCDT, which is consistent with bacterial sulfate reduction. In a three-step extractionâphosphorite dissolutionâextraction procedure, molecular fossils of sulfate-reducing bacteria (di-O-alkyl glycerol ethers and short-chain branched fatty acids i- and ai-C15:0, i- and ai-C17:0, and 10MeC16:0) were preferentially released from the mineral lattice. This suggests that the molecular fossils were tightly bound to carbonate fluorapatite, indicating that sulfate-reducing bacteria were involved in mineral formation. A close association of sulfate-reducing bacteria with large sulfide-oxidizing bacteria, which was previously suggested to favor carbonate fluorapatite precipitation, could neither be confirmed nor excluded for the Miocene Monterey Formation phosphorites