scholarly journals Distribution of microbial biomass, production,respiration, dissolved organic carbon and factors controlling bacterial production across a geostrophic front (Almeria-Oran, SW Mediterranean Sea)

2004 ◽  
Vol 269 ◽  
pp. 1-15 ◽  
Author(s):  
F Van Wambeke ◽  
D Lefèvre ◽  
L Prieur ◽  
R Sempéré ◽  
M Bianchi ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Mediterranean Sea ◽  
Biomass Production ◽  
Bacterial Production

scholarly journals The sensitivity of microbial processes in Icelandic soils to increasing temperatures

2009 ◽  
Vol 6 (4) ◽  
pp. 6749-6780 ◽  
Author(s):  
R. Guicharnaud ◽  
O. Arnalds ◽  
G. I. Paton
Keyword(s):  
Microbial Biomass ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Elevated Temperatures ◽  
Microbial Biomass Carbon ◽  
Biomass Carbon ◽  
Labile Carbon ◽  
Soil Microbial ◽  
Arctic Soils ◽  
Temperature Regimes

Abstract. Temperature change is acknowledged to have a significance effect on soil biological processes and the corresponding sequestration of carbon and the cycling of key nutrients. Soils at high latitudes are likely to be particularly impacted by increases in temperature. In this study, the response of a range of soil microbial parameters (respiration, nutrient availability, microbial biomass carbon, arylphosphatase and dehydrogenase activity) to temperature changes was measured in sub-arctic soils collected from across Iceland. Sample sites reflected two soil temperature regimes (cryic and frigid) and two land uses (pasture and arable). The soils were sampled from the field frozen, equilibrated at −20°C and then incubated for two weeks at −10°C, −2°C, +2°C and +10°C. Respiration and enzymatic activity were temperature dependent. Microbial biomass carbon and nitrogen mineralisation did not change with temperature. The main factor controlling soil respiration at −10°C was the concentration of dissolved organic carbon. At −10°C, dissolved organic carbon accounted for 88% of the fraction of labile carbon which was significantly greater than that recorded at +10°C when dissolved organic carbon accounted for as low as 42% of the labile carbon fraction. Heterotrophic microbial activity is governed by both substrate availability and the temperature and this has been described by the Q10 factor. Elevated temperatures in the short term may have little effect on the size of the microbial biomass but will have significant impacts on the release of carbon through respiration. These results demonstrate that gradual changes in temperature across large areas at higher latitudes will have considerable impacts in relation to global soil carbon dynamics.

Vertical distribution of dissolved organic carbon (DOC) in the Mediterranean Sea

2006 ◽  
Vol 31 ◽  
pp. 205-216 ◽  
Author(s):  
C Santinelli ◽  
BB Manca ◽  
GP Gasparini ◽  
L Nannicini ◽  
A Seritti
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Vertical Distribution ◽  
Mediterranean Sea ◽  
The Mediterranean

DOM DYNAMICS IN THE MEDITERRANEAN SEA. Can a new fluorescence SENSOR contribute to its understanding?

2020 ◽  
Author(s):  
Simona Retelletti Brogi ◽  
Marta Furia ◽  
Giancarlo Bachi ◽  
Vanessa Cardin ◽  
Giuseppe Civitarese ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Mediterranean Sea ◽  
Water Column ◽  
Fluorescence Sensor ◽  
Global Ocean ◽  
Intermediate Water ◽  
Physical Processes ◽  
Open Sea ◽  
The Mediterranean

<p>The Mediterranean Sea (Med Sea) can be considered as a natural laboratory for the study of dissolved organic matter (DOM) dynamics. Despite its small size, it is characterized by the same physical processes and dissolved organic carbon (DOC) concentration and distribution as the global ocean. The Med Sea deep water DOC pool is however older than the Atlantic one and differences in the microbial loop and in DOM dynamics have been observed between the eastern (EMED) and western (WMED) basins. Fluorescence is a fast, cheap and highly sensitive tool to study DOM dynamics, it can therefor give useful information about the main processes affecting DOM distribution.</p><p>The main aims of this study were: (i) to investigate DOM dynamics in both Med Sea basins, in relation to the physical processes (e.g. vertical stratification, irradiation); and (ii) to validate the use of a new fluorescence sensor, developed in the framework of the SENSOR project (POR FESR, Tuscany Region), for the rapid, in-situ measurements of open-sea fluorescent DOM (FDOM). DOM dynamics was investigated by measuring dissolved organic carbon (DOC) and the fluorescence of FDOM. Samples were collected from surface to bottom in 26 stations during the trans-Mediterranean cruise “MSM72”, carried out on board the R/V MARIA S.MERIAN (Institut für Meereskunde der Universität Hamburg). The stations cover both the EMED and the WMED, from Gibraltar to the Crete Island.</p><p>Six fluorescent components were identified by applying the parallel factorial analysis (PARAFAC) to the measured excitation-emission matrices (EEMs). Two components were identified as marine humic-like, two as terrestrial humic-like, one as protein-like and one as polycyclic aromatic hydrocarbon-like (PAH-like).</p><p>Temperature and salinity increased moving from the WMED to the EMED. A surface minimum in salinity, was observed in the WMED, indicating the occurrence of the Atlantic Water (AW), whereas the presence of the Levantine Intermediate Water (LIW) was observed south of Crete. The vertical distribution of both DOC and humic-like FDOM was strongly affected by the water masses circulation and water column stratification. In the upper 200 m, DOC markedly increased from 50 to 80 μM moving eastward, likewise the protein-like component dominates the upper layer and increased moving from Gibraltar to Crete. In contrast, the humic-like components showed a minimum in the surface layer, and a decreasing moving eastward, probably due to photobleaching. The PAH-like component showed its maximum in correspondence with the areas characterized by intensive naval traffic. The accumulation of DOC, observed in the EMED, could be explained by a change in DOM quality, supported by the differences in FDOM.</p><p>In 2 selected stations, the fluorescence of humic-like and protein-like compounds was also measured along the water column by using the new fluorescence sensor and compared with PARAFAC results, in order to evaluate its performance for open sea waters.</p>

Carbon oxidation in the deep Mediterranean Sea: Evidence for dissolved organic carbon source

1989 ◽  
Vol 3 (4) ◽  
pp. 315-335 ◽  
Author(s):  
J. P. Christensen ◽  
T. T. Packard ◽  
F. Q. Dortch ◽  
H. J. Minas ◽  
J. C. Gascard ◽  
...  
Keyword(s):  
Carbon Source ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Mediterranean Sea ◽  
Carbon Oxidation ◽  
Organic Carbon Source
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