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Author |
Granskog, M.A.; Kaartokallio, H.; Thomas, D.N.; Kuosa, H. |
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Title |
Influence of freshwater inflow on the inorganic nutrient and dissolved organic matter within coastal sea ice and underlying waters in the Gulf of Finland (Baltic Sea) |
Type |
Journal Article |
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Year |
2005 |
Publication |
Estuarine, Coastal and Shelf Science |
Abbreviated Journal |
Estuar Coast Shelf Sci |
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Volume |
65 |
Issue |
1-2 |
Pages |
109-122 |
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Keywords |
coastal oceanography; sea ice; river plumes; estuarine chemistry; nutrients (mineral); dissolved organic matter; Baltic Sea |
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Abstract |
A study was conducted to measure the biogeochemical characteristics of freshwater plumes underlying Baltic Sea land-fast ice, and the overlying sea ice. A 40-km long transect was conducted in the northern Baltic Sea in March 2003, following a freshwater plume from its source into the fully mixed open-sea area. The spreading of river outflow below the ice resulted in a well-stratified low-salinity surface layer further out than normally occurs in the open-water period. The freshwaters were high in dissolved organic matter (DOC, DON and CDOM), and inorganic nutrients (ammonium, nitrate and silicate), although the levels of phosphate were low. In general these parameters changed concurrently with salinity in such a way that mixing was conservative. The characteristics of the ice varied from the freshwater source to the open water, with increasing salinity and brine volumes (porosity) occurring in the more open-sea stations. Coinciding with the changes in ice properties there was an increase in sea-ice algal growth in the more marine stations along the transect. Biological activity in the ice was largely confined to bottom ice assemblages. In contrast to the conditions in the underlying water, no relationship between salinity, inorganic nutrients and organic matter was observed in the ice. In particular ammonium, phosphate, DOC and DON were present in excess of those levels predicted from the dilution curves, indicating the presence of considerable DOM production by ice assemblages, inorganic nutrient uptake and remineralization within the ice. |
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Academic Press |
Place of Publication |
San Diego |
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ISSN |
0272-7714 |
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Notes |
Sampling: Nine stations along a 40km salinity gradient from inner Pojo Bay through the Archipelago to the edge of the open sea |
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no |
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Call Number |
refbase @ admin @ Granskog++2005_2 |
Serial |
740 |
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Author |
Kaartokallio, H.; Kuosa, H.; Thomas, D.N.; Granskog, M.A.; Kivi, K. |
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Title |
Biomass, composition and activity of organism assemblages along a salinity gradient in sea ice subjected to river discharge in the Baltic Sea |
Type |
Journal Article |
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Year |
2006 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
30 |
Issue |
2 |
Pages |
183-197 |
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Abstract |
A study was undertaken to examine the activity and composition of the seasonal Baltic Sea land-fast sea-ice biota along a salinity gradient in March 2003 in a coastal location in the SW coast of Finland. Using a multi-variable data set, the less well-known algal and protozoan communities, and algal and bacterial production in relation to the physical and chemical environment were investigated. Also, the first coincident measurements of bacterial production and dissolved organic matter (DOM) in a sea-ice system are reported. Communities in sea ice were clearly autotrophy-dominated with algal biomass representing 79% of the total biomass. Protozoa and rotifers made up 18% of biomass in the ice and bacteria only 3%. Highest biomasses were found in mid-transect bottom ice. Water column assemblages were clearly more heterotrophic: 39% algae, 12% bacteria and 49% for rotifers and protozoa. Few significant correlations existed between DOM and bacterial variables, reflecting the complex origin of ice DOM. Dynamics of dissolved organic carbon, nitrogen and phosphorus (DOC, DON and DOP) were also uncoupled. A functional microbial loop is likely to be present in the studied ice. Existence of an under-ice freshwater plume affects the ecosystem functioning: Under-ice water communities are influenced directly by river-water mixing, whereas the ice system seems to be more independent–the interaction mainly taking place through the formation of active bottom communities. |
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Springer-Verlag |
Place of Publication |
Heidelberg |
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0722-4060 |
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Notes |
Sampling: Nine stations along a 40km salinity gradient from inner Pojo Bay through the Archipelago to the edge of the open sea |
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no |
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Call Number |
refbase @ admin @ Kaartokallio++2006 |
Serial |
744 |
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Author |
Thomas, D.N. |
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Title |
Photosynthetic microbes in freezing deserts |
Type |
Journal Article |
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Year |
2005 |
Publication |
Trends in Microbiology |
Abbreviated Journal |
Trends Microbiol |
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Volume |
13 |
Issue |
3 |
Pages |
87-88 |
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Abstract |
Polar deserts are not devoid of life despite the extreme low temperature and scarcity of water. Recently, patterned stone fields – caused by periglacial activity – have been surveyed in the Arctic and Antarctic. It was found that the productivity of the cyanobacteria and algae (hypoliths) that colonise the underside of the stones is strongly related to the pattern of the stones. The hypolith assemblages were in some cases as productive as lichens, bryophytes and plants that resided nearby. |
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Elsevier Science B.V. |
Place of Publication |
Amsterdam |
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Language |
English |
Summary Language |
English |
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ISSN |
0966-842X |
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no |
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Call Number |
refbase @ admin @ Thomas2005 |
Serial |
755 |
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Author |
Stedmon, C.A.; Thomas, D.N.; Granskog, M.; Kaartokallio, H.; Papadimitriou, S.; Kuosa, H. |
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Title |
Characteristics of dissolved organic matter in Baltic coastal sea ice: allochthonous or autochthonous origins? |
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Journal Article |
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Year |
2007 |
Publication |
Environmental Science & Technology |
Abbreviated Journal |
Environ Sci Technol |
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Volume |
41 |
Issue |
21 |
Pages |
7273-7279 |
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Keywords |
Carbon/analysis; *Humic Substances; Ice Cover/*chemistry; Nitrogen/analysis; Oceans and Seas; Spectrometry, Fluorescence |
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Abstract |
The origin of dissolved organic matter (DOM) within sea ice in coastal waters of the Baltic Sea was investigated using parallel factor (PARAFAC) analysis of DOM fluorescence. Sea ice DOM had distinctly different fluorescence characteristics than that of the underlying humic-rich waters and was dominated by protein-like fluorescence signals. PARAFAC analysis identified five fluorescent components, all of which were present in both sea ice and water. Three humic components were negatively correlated to salinity and concluded to be terrestrially derived material. Baltic Sea ice DOM was found to be a mixture of humic material from the underlying water column incorporated during ice formation and autochthonous material produced by organisms within the ice. Dissolved organic carbon (DOC) and nitrogen (DON) concentrations were correlated to the humic fluorescence, indicating that the majority of the organic carbon and nitrogen in Baltic Sea ice is bound in terrestrial humic material trapped within the ice. This has implications for our understanding of sea ice carbon cycling in regions influenced by riverine input (e.g., Baltic and Arctic coastal waters), as the susceptibility of DOM to degradation and remineralization is largely determined by its source. |
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Address |
Department of Marine Ecology, National Environmental Research Institute, University of Aarhus, Frederiksborgvej 399, 4000 Roskilde, Denmark. cst@dmu.dk |
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English |
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ISSN |
0013-936X |
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Notes |
PMID:18044499 |
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no |
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Call Number |
refbase @ user @ |
Serial |
12979 |
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Author |
Hulatt, C.J.; Thomas, D.N. |
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Title |
Dissolved organic matter (DOM) in microalgal photobioreactors: a potential loss in solar energy conversion? |
Type |
Journal Article |
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Year |
2010 |
Publication |
Bioresource Technology |
Abbreviated Journal |
Bioresour Technol |
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Volume |
101 |
Issue |
22 |
Pages |
8690-8697 |
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Keywords |
Bioreactors/*microbiology; Chlorella vulgaris/*physiology; Culture Media/chemistry; *Electric Power Supplies; Energy Transfer; Organic Chemicals/*chemistry/*metabolism; Photochemistry/*instrumentation; Solubility |
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Abstract |
Microalgae are considered to be a potential alternative to terrestrial crops for bio-energy production due to their relatively high productivity per unit area of land. In this work we examined the amount of dissolved organic matter exuded by algal cells cultured in photobioreactors, to examine whether a significant fraction of the photoassimilated biomass could potentially be lost from the harvestable biomass. We found that the mean maximum amount of dissolved organic carbon (DOC) released measured 6.4% and 17.3% of the total organic carbon in cultures of Chlorellavulgaris and Dunaliella tertiolecta, respectively. This DOM in turn supported a significant growth of bacterial biomass, representing a further loss of the algal assimilated carbon. The release of these levels of DOC indicates that a significant fraction of the photosynthetically fixed organic matter could be lost into the surrounding water, suggesting that the actual biomass yield per hectare for industrial purposes could be somewhat less than expected. A simple and inexpensive optical technique, based on chromophoric dissolved organic matter (CDOM) measurements, to monitor such losses in commercial PBRs is discussed. |
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School of Ocean Sciences, College of Natural Sciences, Bangor University, Menai Bridge, Anglesey, UK. osp418@bangor.ac.uk |
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English |
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0960-8524 |
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PMID:20634058 |
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Call Number |
refbase @ user @ |
Serial |
12981 |
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