Laboratory measurements of reflection coefficient from a water-mud interface after varying bottom water salinity

2016 ◽  
Author(s):  
Gabriel R. Venegas ◽  
Preston S. Wilson ◽  
Jason D. Sagers
Keyword(s):  
Reflection Coefficient ◽  
Bottom Water ◽  
Water Salinity ◽  
Laboratory Measurements

scholarly journals Large variations in iron input to an oligotrophic Baltic Sea estuary: impact on sedimentary phosphorus burial

2018 ◽  
Vol 15 (22) ◽  
pp. 6979-6996 ◽  
Author(s):  
Wytze K. Lenstra ◽  
Matthias Egger ◽  
Niels A. G. M. van Helmond ◽  
Emma Kritzberg ◽  
Daniel J. Conley ◽  
...  
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Reactive Transport ◽  
Bottom Water ◽  
Transport Model ◽  
Coastal Sediments ◽  
Estuarine Sediments ◽  
Water Salinity ◽  
The Baltic Sea ◽  
The Baltic

Abstract. Estuarine sediments are key sites for removal of phosphorus (P) from rivers and the open sea. Vivianite, an Fe(II)-P mineral, can act as a major sink for P in Fe-rich coastal sediments. In this study, we investigate the burial of P in the Öre Estuary in the northern Baltic Sea. We find much higher rates of P burial at our five study sites (up to ∼0.145 molm-2yr-1) when compared to more southern coastal areas in the Baltic Sea with similar rates of sedimentation. Detailed study of the sediment P forms at our site with the highest rate of sedimentation reveals a major role for P associated with Fe and the presence of vivianite crystals below the sulfate methane transition zone. By applying a reactive transport model to sediment and porewater profiles for this site, we show that vivianite may account for up to ∼40 % of total P burial. With the model, we demonstrate that vivianite formation is promoted in sediments with a low bottom water salinity and high rates of sedimentation and Fe oxide input. While high rates of organic matter input are also required, there is an optimum rate above which vivianite formation declines. Distinct enrichments in sediment Fe and sulfur at depth in the sediment are attributed to short periods of enhanced input of riverine Fe and organic matter. These periods of enhanced input are linked to variations in rainfall on land and follow dry periods. Most of the P associated with the Fe in the sediment is likely imported from the adjacent eutrophic Baltic Proper. Our work demonstrates that variations in land-to-sea transfer of Fe may act as a key control on burial of P in coastal sediments. Ongoing climate change is expected to lead to a decrease in bottom water salinity and contribute to continued high inputs of Fe oxides from land, further promoting P burial as vivianite in the coastal zone of the northern Baltic Sea. This may enhance the role of this oligotrophic area as a sink for P imported from eutrophic parts of the Baltic Sea.

scholarly journals Reconstruction of Pacific Ocean bottom water salinity during the Last Glacial Maximum

2014 ◽  
Vol 41 (8) ◽  
pp. 2914-2920 ◽  
Author(s):  
Tania Lado Insua ◽  
Arthur J. Spivack ◽  
Dennis Graham ◽  
Steven D'Hondt ◽  
Kathryn Moran
Keyword(s):  
Pacific Ocean ◽  
Last Glacial Maximum ◽  
Bottom Water ◽  
Glacial Maximum ◽  
Water Salinity ◽  
Ocean Bottom ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

scholarly journals Variations in river input of iron impact sedimentary phosphorus burial in an oligotrophic Baltic Sea estuary

2018 ◽  
Author(s):  
Wytze K. Lenstra ◽  
Matthias Egger ◽  
Niels A. G. M. van Helmond ◽  
Emma Kritzberg ◽  
Daniel J. Conley ◽  
...  
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Reactive Transport ◽  
Bottom Water ◽  
Coastal Sediments ◽  
Estuarine Sediments ◽  
Water Salinity ◽  
The Baltic Sea ◽  
The Baltic ◽  
Organic Matter Input

Abstract. Estuarine sediments are key sites for removal of phosphorus (P) from rivers and the open sea. Vivianite, an iron (Fe)(II)-P mineral, can act as a major sink for P in Fe-rich coastal sediments. In this study, we investigate the burial of P in the Öre Estuary in the northern Baltic Sea. We find much higher rates of P burial at our five study sites (up to ~ 0.145 mol m−2 yr−1) when compared to more southern coastal areas in the Baltic Sea with similar rates of sedimentation. Detailed study of the sediment P forms at our site with the highest rate of sedimentation reveals a major role for P associated with Fe and the presence of vivianite crystals below the sulfate methane transition zone. By applying a reactive transport model to sediment and porewater profiles for this site, we show that vivianite may account for up to 40 % of total P burial. With the model, we demonstrate that vivianite formation is promoted in sediments with a low bottom water salinity and high rates of sedimentation and Fe oxide input. While high rates of organic matter input are also required, there is an optimum rate above which vivianite formation declines. Distinct enrichments in sediment Fe and sulfur at depth in the sediment are attributed to short periods of enhanced riverine Fe and organic matter input linked to variations in rainfall on land. Most of the P associated with the Fe in the sediment is likely imported from the adjacent eutrophic Baltic Proper. Our work demonstrates that variations in land-to-sea transfer of Fe may act as a key control on burial of P in coastal sediments. Ongoing climate change is expected to lead to a decrease in bottom water salinity and contribute to continued high inputs of Fe oxides from land, further promoting P burial as vivianite in the coastal zone of the northern Baltic Sea. This may enhance the role of this oligotrophic area as a sink for P imported from eutrophic parts of the Baltic Sea.

scholarly journals Redescription of Echinoderes levanderi Karling, 1954 (Kinorhyncha: Cyclorhagida) – a kinorhynch tolerant to very low salinities

2018 ◽  
Author(s):  
Martin V. Sørensen
Keyword(s):  
Sexual Dimorphism ◽  
Bottom Water ◽  
New Records ◽  
Water Salinity ◽  
Distributional Range ◽  
Sieve Plates ◽  
Bothnian Bay

The kinorhynch species Echinoderes levanderi Karling, 1954 is redescribed. The species can now be recognized by the presence of spines in middorsal positions on segments 4–8, and in lateroventral positions on segments 6–9, with lateroventral spines on segment 9 showing sexual dimorphism; tubes in subdorsal and ventrolateral positions on segment 2, in sublateral positions on segments 4 and 8, in lateroventral positions on segment 5, and in laterodorsal positions on segment 10. Furthermore, the enlarged sieve plates on segment 9 make the species highly characteristic. New records of the species extend its distributional range into the Bothnian Bay where the bottom water salinity drops below 5 ppt, which is the lowest salinity recorded for a habitat with kinorhynchs.

scholarly journals The role of ocean cooling in setting glacial southern source bottom water salinity

2012 ◽  
Vol 27 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. D. Miller ◽  
J. F. Adkins ◽  
D. Menemenlis ◽  
M. P. Schodlok
Keyword(s):  
Bottom Water ◽  
Water Salinity

Holocene hydrographical changes of the eastern Laptev Sea (Siberian Arctic) recorded in δ18O profiles of bivalve shells

2004 ◽  
Vol 61 (1) ◽  
pp. 32-41 ◽  
Author(s):  
Thomas Mueller-Lupp ◽  
Henning A. Bauch ◽  
Helmut Erlenkeuser
Keyword(s):  
Oxygen Isotope ◽  
Sea Level ◽  
Bottom Water ◽  
River Mouth ◽  
Water Salinity ◽  
Laptev Sea ◽  
Modern Analogue ◽  
History Of ◽  
The Laptev Sea ◽  
Bivalve Shells

Oxygen isotope profiles along the growth axis of fossil bivalve shells of Macoma calcarea were established to reconstruct hydrographical changes in the eastern Laptev Sea since 8400 cal yr B.P. The variability of the oxygen isotopes (δ18O) in the individual records is mainly attributed to variations in the salinity of bottom waters in the Laptev Sea with a modern ratio of 0.50‰/salinity. The high-resolution δ18O profiles exhibit distinct and annual cycles from which the seasonal and annual salinity variations at the investigated site can be reconstructed. Based on the modern analogue approach oxygen isotope profiles of radiocarbon-dated bivalve shells from a sediment core located northeast of the Lena Delta provide seasonal and subdecadal insights into past hydrological conditions and their relation to the Holocene transgressional history of the Laptev Sea shelf. Under the assumption that the modern relationship between δ18Ow and salinity has been constant throughout the time, the δ18O of an 8400-cal-yr-old bivalves would suggest that bottom-water salinity was reduced and the temperature was slightly warmer, both suggesting a stronger mixture of riverine water to the bottom water. Reconstruction of the inundation history of the Laptev Sea shelf indicates local sea level ∼27 m below present at this time and a closer proximity of the site to the coastline and the Lena River mouth. Due to continuing sea level rise and a southward retreat of the river mouth, bottom-water salinity increased at 7200 cal yr B.P. along with an increase in seasonal variability. Conditions comparable to the modern hydrography were achieved by 3800 cal yr B.P.

Sign in / Sign up

Export Citation Format

Share Document