SERVICE D’OBSERVATION  DYFAMED

Head of program : Jean-Claude MARTY
Marty@obs-vlfr.fr

Responsable of atmospheric parameters : Christophe MIGON
Migon@obs-vlfr.fr

Observatoire Oceanologique
L.O.V
SO DYFAMED
Quai de la Darse, BP 8
06238 VILLEFRANCHE :MER   (France)

SAMPLING PROTOCOL

Aerosol :

Aerosols are collected by pumping surrounding air through a cellulose-acetate membrane Sartorius SM 11106 (diameter 47 mm, porosity 0.45 micrometre), placed on a filter holder Sartorius SM 16510, raised to the top of a 6 m-high mast and connected to pumps (Reciprotor, 40 W) and counters (Gallus). (Figure 2)
The filters are not cleaned by acid treatment owing to the potential deformation of the filter pores leading to inhomogeneity of the aerosol filtration.
The pumping rate approximately  ranges between 
 20 m3 per hour (typical pumping duration : 1 day : 1986-1987)
 1 m3 per hour   (typical pumping duration : 1 week :  since 1992)

Rainwater :
Rainwater is collected using an automatic rain collector (Figure) that opens when it rains and not under the influence of fog or dew.
Total fluxes were sampled out of this purpose. See DYFAMED

ANALYSIS

Sample mineralization
The non-soluble fraction of atmospheric samples (aerosol + residual fraction in rainwater) is mineralized prior to analysis. The organic matrix is destroyed with an oxidizing attack (HNO3), and mineral aluminosilicate matrixes are destroyed with HF. The sample is freeze-dried and weighed (weighing machine Sartorius MC 1, accuracy 0.01 mg) in 7 ml flasks, where the mineralization will take place. Then, the procedure can be decomposed in two main steps:
1) 900 µl HNO3 65% are added to each flask. The flasks are closed and put into larger bottles (60 ml) that act as expansion cells, overcome acidic evaporation and help to prevent contamination. This apparatus is left 2 - 3 hours in an oven at 60 °C, and then 3 - 4 hours at 150 °C, until remains a black dry residue.
2) 200 µl HNO3 65% and 200 µl HF 40% are added to the remainder. The samples are put in an oven 2 - 3 hours at 60 °C, and then 3 - 4 hours at 150 °C, until a white dry residue is obtained. This residue is ultrasonically dissolved in 0.5 ml HNO3 1N. The samples are then made up with Milli-Q water to 5 ml.
All reagents were provided by Merck (Darmstadt, Germany), quality Suprapur (HCl), Normapur (HNO3) and Pro Analysis (HF).

ICP-AES analysis
Al, Na and Zn are analysed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). ICP-AES measurements are performed with a Jobin-Yvon JY 38 S Ultrace analyser, equipped with a Scott nebulizer. Detection limits are 25, 50 and 5 mg l-1 for Al, Na and Zn, respectively. Blank values (filter + reagents) are always lower than the detection limits.The analytical procedure is checked regularly using certified reference materials provided by the National Research Council, Ottawa, Canada; the discrepancy is generally less than 10% (Sandroni, 2000). All analyses are carried out in Class 100 laminar airflow benches located within a clean room.
More details can be found in Journel (1998) and Sandroni (2000).