relationship between aerosol methanesulfonate and remotely sensed phytoplankton activity in central...
TRANSCRIPT
Relationship between aerosol methanesulfonate and remotely sensed phytoplankton activity in central
Mediterranean Sea
S. Becagli a, L. Lazzara b, F. Fani b, C. Marchese b, R. Traversi a, M. Severi a, A. di Sarra c,D. Sferlazzo d, S. Piacentino e, C. Bommarito e, R. Udisti a
a Department of Chemistry, University of Florence, Sesto F.no, Florence, I-50019, Italyb Dep. of Biology, University of Florence, I- 50019 Sesto Fiorentino, Florence, Italy
c ENEA, Laboratory for Earth Observations and Analyses, I-00123 Roma, Italyd ENEA, Laboratory for Earth Observations and Analyses, I-92010 Lampedusa, Italy
e ENEA, Laboratory for Earth Observations and Analyses, I-90141 Palermo, Italy
Earth observation for ocean-atmosphere interaction science | ESA-ESRIN |28-30 October 2014
From : Stefesl et al., Biogeochemistry (2007) 83:245–275
MSA Biogenic productivity
Influence of global change on biogenic productivity.
Feedback processes (CLAW hypothesis)
Charlson, R. J., Lovelock J.E., Andreae, M. O. and Warren, S. G. (1987). Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate. Nature, 326, 655-661.
NASA/MODIS
35.5°N, 12.6°E
N
Power plant
Airport
Town
http://www.lampedusa.enea.it/
http://www.lampedusa.enea.it/
Since Jun 2004 PM10 sampling on Teflon filter…..sampling in progress
Aerosol sampling Campaigns
Ion Chromatography Na+, NH4
+, K+, Mg2+, Ca2+,
Cl-, NO3-, SO4
2-, MS-, Ac, For, Gly, Ox
Al, Cd, Ba, Pb, Si, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Mo
ICP AES HNO3 pH1.5
PIXE: elements total content
Dept. of Chemistry, Univ. of Florence
Dept. of Physics and INFN
Cuting in clean conditions
maximum value of specific absorption in the chlorophyll spectrum (about at 435 nm)
maximum quantum yield of phototrophic growth
length of day depth of euphotic layerfraction of PAR potentially absorbed by all algal species. PAR (W/m2) was derived from measurements of global downward irradiance.
concentration of chlorophyll-a
f (x) is a function reproducing the photosynthesis-irradiancerelationship (P-E curve)
x is the ratio betweenPUR and Ek (photo-adaptation irradiance)
CALCULATION 1/2
Primary Production – PP g C m-2 d-1 Biooptical and physiologically based model of the WRDM (Wavelength-Depth-Resolved-Model) developed by Morel (1991).
chlorophyll-a map calculated by CHL MedOC3 algorithm for the year 2007.
Map of Primary Productivity in the year 2006 calculated for the surroundig area of Lampedusa Island
CALCULATION 2/2
PB : chlorophyll specific production index or assimilation number i.e. the rate of photosynthetic carbon assimilation per weight of chlorophyll-a
PB = PP/Chl (integrated values for the euphotic layer) [gC gChl-1 d-1]
Daily solar radiation dose (SRD) in the upper mixed layer:
SRD = f (PAR, MLD, PAR att coeff)
daily irradiance measured atLampedusa
Mixed Layer Depth climatology of the Naval Research Laboratory
PAR attenuation coefficients from oceancolor satellite-derived climatologies (SeaWiFS, http://disc.sci.gsfc.nasa.gov/giovanni/overview/index.html).
The “summerParadox”
seasonal changes in the phytoplankton composition
Phytoplankton stress due to high irradiance (UV and visible) and low nutrient availability associated with a shallow mixed layer depthduring summer.
Chl
SRD
PP
PB
MS-
DMS in sea water
MS- in atmospheric aerosol
Over Western Mediterranean: Positive anomaly of GPH at all atmospheric levels
Strong subsidence cloud free conditions
weak winds leading to short-fetch backward trajectories
E. huxleyi abundances in the Sicily Channel in spring 1996 (Bohm et al., 1998)
High MSA in spring 2005 in the Sicily Channel (this work)
These steady conditions could have allowed an earlier initiation of the spring bloom
favoring the growth of small flagellates and prymnesiophytes (high DMS producer) instead of diatoms
biological causes……the weak winds over the Mediterranean Sea prevent a strong vertical mixing of the water column, thus reducing the upper mixed layer depth and producing effects similar to an increase of SRD
Atmospheric causes….the stable atmospheric conditions determine the accumulation of the newly formed MS- in the marine boundary layer.
ConclusionsStatistically significant linear relationship between
MS- – PB (r2 = 0.84, p < 0.001),
MS- – SRD (r2 = 0.87, p < 0.001)
MS- in the Mediterranean Sea is mainly related to the phytoplankton physiology (growth rate, photo adaptation), which in turn depends on stressfactors (i.e., excess radiation and water column stratification duringsummer in the Mediterranean).
Experimental derivation PB from atmospheric parameters
validation of biogeochemical model results
Improvement in their ability to predict phytoplankton growth rates under light and nutrient limitation
modeling of the ocean carbon cycle at the global scale.
Future work
MSA-PB Long term correlation
Effect of Saharan dust episodes on PP and PB
Study of chemical composition of deposition (see poster Santinelli), dust deposition velocity and effect of dust deposition in different oligotrophic condition.
Thank you for your attention!!