The Chemistry of Near-Surface Seawater

1986 ◽  
pp. 41-51 ◽  
Author(s):  
Peter S. Liss
Keyword(s):  
Surface Seawater ◽  
Near Surface

scholarly journals Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region

2012 ◽  
Vol 9 (3) ◽  
pp. 1041-1051 ◽  
Author(s):  
C. Zindler ◽  
I. Peeken ◽  
C. A. Marandino ◽  
H. W. Bange
Keyword(s):  
Surface Waters ◽  
Coastal Upwelling ◽  
Environmental Control ◽  
Hot Spot ◽  
Local Source ◽  
Surface Seawater ◽  
Near Surface ◽  
Northwest Africa ◽  
N:P Ratios ◽  
A Minor

Abstract. Dimethylsulphide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp) were measured in near-surface waters along the Mauritanian coast, Northwest Africa, during the upwelling season in February 2008. DMS, DMSPd and DMSPp surface concentrations of up to 10 nmol L−1, 15 nmol L−1 and 990 nmol L−1, respectively, were measured. However, the DMS concentrations measured are in the low range compared to other upwelling regions. The maximum DMSPp concentration is the highest reported from upwelling regions so far, which might indicate that the Mauritanian upwelling is a hot spot for DMSP. Within the phytoplankton groups, dinoflagellates were identified as important contributors to DMS concentrations, while other algae seemed to have only a minor or no influence on DMS and DMSP concentrations. A pronounced switch from high DMSP to high DMS concentrations was observed when the nitrogen to phosphorus ratio (N:P) was below 7. The high DMS/DMSP ratios at N:P ratios <7 indicate that nitrogen limitation presumably triggered a switch from DMSP to DMS independent of the species composition. Our results underline the importance of coastal upwelling regions as a local source for surface seawater sulphur.

scholarly journals Assessing the potential for DMS enrichment at the sea-surface and its influence on air–sea flux

2016 ◽  
Author(s):  
C. F. Walker ◽  
M. J. Harvey ◽  
M. J. Smith ◽  
T. G. Bell ◽  
E. S. Saltzman ◽  
...  
Keyword(s):  
Sea Surface ◽  
Gas Transfer ◽  
Surface Microlayer ◽  
Surface Seawater ◽  
Biological Factors ◽  
Near Surface ◽  
Wind Speeds ◽  
Factors Influencing ◽  
Sea Surface Microlayer ◽  
High Enrichment

Abstract. The flux of dimethylsulfide (DMS) to the atmosphere is generally inferred using water sampled at or below 2 m depth, thereby excluding any concentration anomalies at the air–sea interface. Two independent techniques were used to assess the potential for near-surface DMS enrichment to influence DMS emissions and also identify the factors influencing enrichment. DMS measurements in productive frontal waters over the Chatham Rise, east of New Zealand, did not identify any significant DMS gradients between 0.01 and 6 m in sub-surface seawater, whereas DMS enrichment in the sea-surface microlayer was variable, with a mean enrichment factor (EF; the concentration ratio between DMS in the SSM and in sub-surface water) of 1.7. Physical and biological factors influenced sea-surface microlayer DMS concentration, with high enrichment (EF > 1.3) only recorded in a dinoflagellate-dominated bloom, and associated with low to medium wind speeds and near-surface temperature gradients. On occasion, high DMS enrichment preceded periods when the air–sea DMS flux, measured by eddy covariance, exceeded the flux calculated using COARE parameterised gas transfer velocities and measured sub-surface seawater DMS concentrations. The results of these two independent approaches suggest that air–sea emissions may be influenced by near-surface DMS production under certain conditions, and highlights the need for further study to constrain the magnitude and mechanisms of DMS production in the sea surface microlayer.

Pseudonitzschia species found in digestive tracts of northern anchovies [Engraulis mordax)

1995 ◽  
Vol 73 (4) ◽  
pp. 642-647 ◽  
Author(s):  
Kellie L. McGinness ◽  
John D. McEachran ◽  
Greta A. Fryxell
Keyword(s):  
Domoic Acid ◽  
Stomach Contents ◽  
Monterey Bay ◽  
Diatom Species ◽  
Surface Seawater ◽  
Surrounding Water ◽  
Near Surface ◽  
Pseudonitzschia Australis ◽  
Engraulis Mordax ◽  
Pennate Diatoms

The diatom species Pseudonitzschia australis Frenguelli has been implicated as the source of the domoic acid that contaminated anchovy species in Monterey Bay, California, during 1991. In other geographic areas, as well as in laboratory cultures of isolates obtained from various geographic areas, other Pseudonitzschia species have been shown to produce domoic acid. The stomach contents of anchovies caught in Monterey Bay during the following summer were analyzed to identify and determine the abundance of each of the Pseudonitzschia species present. Pseudonitzschia species present in net-tow samples taken at the same time from Monterey Bay were also recorded. In the stomach samples, nine different Pseudonitzschia species were found, including four that have produced domoic acid either under natural or laboratory conditions. These findings illustrate the risk of possible neurotoxin accumulation inherent in the diets of the anchovies studied. The planktophagous diet of the anchovies reflected the plankton composition of the surrounding water and also demonstrates the anchovies' ability to filter pennate diatoms from the near-surface seawater.

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