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Author |
Carver, S.M.; Hulatt, C.J.; Thomas, D.N.; Tuovinen, O.H. |
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Title |
Thermophilic, anaerobic co-digestion of microalgal biomass and cellulose for H2 production |
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Journal Article |
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Year |
2011 |
Publication |
Biodegradation |
Abbreviated Journal |
Biodegradation |
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Volume |
22 |
Issue |
4 |
Pages |
805-814 |
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Keywords |
Anaerobiosis; Biodegradation, Environmental; Biofuels; Biomass; Bioreactors; Cellulose/*metabolism; Chlorella vulgaris/*metabolism/microbiology; Chromatography, High Pressure Liquid; Fatty Acids, Volatile/biosynthesis; *Fermentation; *Hydrogen/metabolism; Microalgae/*metabolism/microbiology; Microbial Consortia |
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Abstract |
Microalgal biomass has been a focus in the sustainable energy field, especially biodiesel production. The purpose of this study was to assess the feasibility of treating microalgal biomass and cellulose by anaerobic digestion for H2 production. A microbial consortium, TC60, known to degrade cellulose and other plant polymers, was enriched on a mixture of cellulose and green microalgal biomass of Dunaliella tertiolecta, a marine species, or Chlorella vulgaris, a freshwater species. After five enrichment steps at 60 degrees C, hydrogen yields increased at least 10% under all conditions. Anaerobic digestion of D. tertiolecta and cellulose by TC60 produced 7.7 mmol H2/g volatile solids (VS) which were higher than the levels (2.9-4.2 mmol/g VS) obtained with cellulose and C. vulgaris biomass. Both microalgal slurries contained satellite prokaryotes. The C. vulgaris slurry, without TC60 inoculation, generated H2 levels on par with that of TC60 on cellulose alone. The biomass-fed anaerobic digestion resulted in large shifts in short chain fatty acid concentrations and increased ammonium levels. Growth and H2 production increased when TC60 was grown on a combination of D. tertiolecta and cellulose due to nutrients released from algal cells via lysis. The results indicated that satellite heterotrophs from C. vulgaris produced H2 but the Chlorella biomass was not substantially degraded by TC60. To date, this is the first study to examine H2 production by anaerobic digestion of microalgal biomass. The results indicate that H2 production is feasible but higher yields could be achieved by optimization of the bioprocess conditions including biomass pretreatment. |
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Department of Microbiology, Ohio State University, 484 W. 12th Ave., Columbus, OH 43210, USA. carver.84@gmail.com |
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English |
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ISSN |
0923-9820 |
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PMID:20878208 |
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Call Number |
refbase @ user @ |
Serial |
12982 |
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Author |
Raike, A.; Kortelainen, P.; Mattsson, T.; Thomas, D.N. |
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Title |
36 year trends in dissolved organic carbon export from Finnish rivers to the Baltic Sea |
Type |
Journal Article |
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Year |
2012 |
Publication |
The Science of the Total Environment |
Abbreviated Journal |
Sci Total Environ |
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Volume |
435-436 |
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Pages |
188-201 |
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Keywords |
Baltic States; Carbon/*chemistry; Finland; Hydrology; Oceans and Seas; Rivers/*chemistry; Seasons; Soil/chemistry |
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Abstract |
Increasing dissolved organic carbon (DOC) concentrations in lakes, rivers and streams in northern mid latitudes have been widely reported during the last two decades, but relatively few studies have dealt with trends in DOC export. We studied the export of DOC from Finnish rivers to the Baltic Sea between 1975 and 2010, and estimated trends in DOC fluxes (both flow normalised and non-normalised). The study encompassed the whole Finnish Baltic Sea catchment area (301,000 km(2)) covering major land use patterns in the boreal zone. Finnish rivers exported annually over 900,000 t DOC to the Baltic Sea, and the mean area specific export was 3.5 t km(-2). The highest export (7.3t km(-2)) was measured in peat dominated catchments, whereas catchments rich in lakes had the lowest export (2.2 t km(-2)). Inter-annual variation in DOC export was high and controlled mainly by hydrology. There was no overall trend in the annual water flow, although winter flow increased in northern Finland over 36 years. Despite the numerous studies showing increases in DOC concentrations in streams and rivers in the northern hemisphere, we could not find any evidence of increases in DOC export to the northern Baltic Sea from Finnish catchments since 1975. |
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Finnish Environment Institute (SYKE), P.O. Box 140, FI-00251, Helsinki, Finland. antti.raike@ymparisto.fi |
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0048-9697 |
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PMID:22854090 |
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refbase @ user @ |
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12986 |
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Author |
Brierley, A.S.; Thomas, D.N. |
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Title |
Ecology of southern ocean pack ice |
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Journal Article |
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Year |
2002 |
Publication |
Advances in marine biology |
Abbreviated Journal |
Adv Mar Biol |
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Volume |
43 |
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Pages |
171-276 |
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Keywords |
Animals; Antarctic Regions; Birds; Crustacea; Ecology; *Ecosystem; Environment; Fishes; *Ice; *Marine Biology; Oceans and Seas; Phytoplankton; Population Dynamics; Research Support, Non-U.S. Gov't; Seasons; *Seawater; Water Microbiology; Whales |
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Abstract |
Around Antarctica the annual five-fold growth and decay of sea ice is the most prominent physical process and has a profound impact on marine life there. In winter the pack ice canopy extends to cover almost 20 million square kilometres--some 8% of the southern hemisphere and an area larger than the Antarctic continent itself (13.2 million square kilometres)--and is one of the largest, most dynamic ecosystems on earth. Biological activity is associated with all physical components of the sea-ice system: the sea-ice surface; the internal sea-ice matrix and brine channel system; the underside of sea ice and the waters in the vicinity of sea ice that are modified by the presence of sea ice. Microbial and microalgal communities proliferate on and within sea ice and are grazed by a wide range of proto- and macrozooplankton that inhabit the sea ice in large concentrations. Grazing organisms also exploit biogenic material released from the sea ice at ice break-up or melt. Although rates of primary production in the underlying water column are often low because of shading by sea-ice cover, sea ice itself forms a substratum that provides standing stocks of bacteria, algae and grazers significantly higher than those in ice-free areas. Decay of sea ice in summer releases particulate and dissolved organic matter to the water column, playing a major role in biogeochemical cycling as well as seeding water column phytoplankton blooms. Numerous zooplankton species graze sea-ice algae, benefiting additionally because the overlying sea-ice ceiling provides a refuge from surface predators. Sea ice is an important nursery habitat for Antarctic krill, the pivotal species in the Southern Ocean marine ecosystem. Some deep-water fish migrate to shallow depths beneath sea ice to exploit the elevated concentrations of some zooplankton there. The increased secondary production associated with pack ice and the sea-ice edge is exploited by many higher predators, with seals, seabirds and whales aggregating there. As a result, much of the Southern Ocean pelagic whaling was concentrated at the edge of the marginal ice zone. The extent and duration of sea ice fluctuate periodically under the influence of global climatic phenomena including the El Nino Southern Oscillation. Life cycles of some associated species may reflect this periodicity. With evidence for climatic warming in some regions of Antarctica, there is concern that ecosystem change may be induced by changes in sea-ice extent. The relative abundance of krill and salps appears to change interannually with sea-ice extent, and in warm years, when salps proliferate, krill are scarce and dependent predators suffer severely. Further research on the Southern Ocean sea-ice system is required, not only to further our basic understanding of the ecology, but also to provide ecosystem managers with the information necessary for the development of strategies in response to short- and medium-term environmental changes in Antarctica. Technological advances are delivering new sampling platforms such as autonomous underwater vehicles that are improving vastly our ability to sample the Antarctic under sea-ice environment. Data from such platforms will enhance greatly our understanding of the globally important Southern Ocean sea-ice ecosystem. |
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Gatty Marine Laboratory, School of Biology, University of St Andrews, Fife, KY16 8LB, UK. andrew.brierley@st-andrews.ac.uk |
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English |
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ISSN |
0065-2881 |
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Notes |
PMID:12154613 |
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no |
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Call Number |
refbase @ user @ |
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317 |
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Author |
Granskog, M.A.; Kaartokallio, H.; Kuosa, H.; Thomas, D.N.; Ehn, J.; Sonninen, E. |
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Title |
Scales of horizontal patchiness in chlorophyll a, chemical and physical properties of landfast sea ice in the Gulf of Finland (Baltic Sea) |
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Journal Article |
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Year |
2005 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
28 |
Issue |
4 |
Pages |
276-283 |
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Abstract |
Horizontal variation of first-year landfast sea ice properties was studied in the Gulf of Finland, the Baltic Sea. Several scales of variation were considered; a number of arrays with core spacings of 0.2, 2 and 20 m were sampled at different stages of the ice season for small-scale patchiness. Spacing between these arrays was from hundreds of meters to kilometers to study mesoscale variability, and once an onshore–offshore 40-km transect was sampled to study regional scale variability. Measured variables included salinity, stable oxygen isotopes (δ18O), chlorophyll a (chl-a), nutrients and dissolved organic carbon. On a large scale, a combination of variations in the under-ice water salinity (ice porosity), nutrient supply and the stage of ice development control the build-up of ice algal biomass. At scales of hundreds of meters to kilometers, there was significant variability in several parameters (salinity, chl-a, snow depth and ice thickness). Analyses of the data from the arrays did not show evidence of significant patchiness at scales <20 m for algal biomass. The results imply that the sampling effort in Baltic Sea ice studies should be concentrated on scales of hundreds of meters to kilometers. Using the variations observed in the study area, the estimate for depth-integrated algal biomass in landfast sea ice in the Gulf of Finland (March 2003) is 5.5±4.4 mg chl-a m-2. |
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Granskog: Arctic Centre, University of Lapland, P.O. Box 122, 96101 Rovaniemi, Finland |
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Springer-Verlag |
Place of Publication |
Heidelberg |
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English |
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English |
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0722-4060 |
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Baltic Sea; Gulf of Finland |
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no |
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Call Number |
refbase @ admin @ Granskog++2005 |
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739 |
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Author |
Granskog, M.; Kaartokallio, H.; Kuosa, H.; Thomas, D.N.; Vainio, J. |
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Title |
Sea ice in the Baltic Sea – A review |
Type |
Journal Article |
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Year |
2006 |
Publication |
Estuarine, Coastal and Shelf Science |
Abbreviated Journal |
Estuar Coast Shelf Sci |
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70 |
Issue |
1-2 |
Pages |
145-160 |
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Keywords |
sea ice; Baltic Sea; biogeochemistry; plankton; seasons |
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Abstract |
Although the seasonal ice cover of the Baltic Sea has many similarities to its oceanic counterpart in Polar Seas and Oceans, there are many unique characteristics that mainly result from the brackish waters from which the ice is formed, resulting in low bulk salinities and porosities. In addition, due to the milder climate than Polar regions, the annual maximum ice extent is highly variable, and rain and freeze-melt cycles can occur throughout winter. Up to 35% of the sea ice mass can be composed from metamorphic snow, rather than frozen seawater, and in places snow and superimposed ice can make up to 50% of the total ice thickness. There is pronounced atmospheric deposition of inorganic nutrients and heavy metals onto the ice, and in the Bothnian Bay it is estimated that 5% of the total annual flux of nitrogen and phosphorus and 20–40% of lead and cadmium may be deposited onto the ice fields from the atmosphere. It is yet unclear whether or not the ice is simply a passive store for atmospherically deposited compounds, or if they are transformed through photochemical processes or biological accumulation before released at ice and snow melt.As in Polar sea ice, the Baltic ice can harbour rich biological assemblages, both within the ice itself, and on the peripheries of the ice at the ice/water interface. Much progress has been made in recent years to study the composition of these assemblages as well as measuring biogeochemical processes within the ice related to those in underlying waters. The high dissolved organic matter loading of Baltic waters and ice result in the ice having quite different chemical characteristics than those known from Polar Oceans. The high dissolved organic material load is also responsible in large degree to shape the optical properties of Baltic Sea ice, with high absorption of solar radiation at shorter wavelengths, a prerequisite for active photochemistry of dissolved organic matter.Land-fast ice in the Baltic also greatly alters the mixing characteristics of river waters flowing into coastal waters. River plumes extend under the ice to a much greater distance, and with greater stability than in ice-free conditions. Under-ice plumes not only alter the mixing properties of the waters, but also result in changed ice growth dynamics, and ice biological assemblages, with the underside of the ice being encased, in the extreme case, with a frozen freshwater layer.There is a pronounced gradient in ice types from more saline ice in the south to freshwater ice in the north. The former is characteristically more porous and supports more ice-associated biology than the latter. Ice conditions also vary considerably in different parts of the Baltic Sea, with ice persisting for over half a year in the northernmost part of the Baltic Sea, the Bothnian Bay. In the southern Baltic Sea, ice appears only during severe winters. |
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Address |
Granskog: Arctic Centre, University of Lapland, P.O. Box 122, FI-96101 Rovaniemi, Finland |
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Elsevier Science BV |
Place of Publication |
Amsterdam |
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ISSN |
0272-7714 |
ISBN |
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Baltic Sea |
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Notes |
Review |
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Call Number |
refbase @ admin @ Granskog++2006 |
Serial |
738 |
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