Total Suspended atmospheric Particles (TSP) were collected in eastern Med. (Crete, N=77) and West Med. (Luminy Campus, N=25) by using high-volume air sampler. The TSP particles were analysed initially for Total Phosphorus (TP), Phosphate and condensed inorganic P (the pyro-, meta- and other inorganic polyphosphates forms), according to the protocol described in Violaki et al., (2018). Total Organic-P was calculated by subtracting all inorganic forms of P from TP. The results are depicted in Table. 1 (Fig.1a) for both the West and East Med. Almost 30% of TP is attributed to organic forms of P in the atmosphere of the MS. However, the higher average concentration of organic-P was observed in E. Med., as in the sampling period were recorded more dust events from the Sahara comparing with W. Med.
The aerosols samples (TSP) were analysed for organic P compounds of biological origin (e.g. phospholipids, ATP-like compounds, phytic acid, nucleic acids) and of anthropogenic origin (e.g. OPEs, organophosphorus pesticides, and degradation products of chemical weapons), by liquid chromatography coupled to mass spectrometry at the time of flight mode (Q-TOF-LC/MS) after optimization of the analytical protocols for the matrix of the aerosol samples. Regarding the anthropogenic atmospheric organic P, important role played the OPEs compounds following by organophosphorus pesticides, while degradation products of chemical weapons were not detected. Five pesticides were found in 27 samples in East Med. The most abundant were chlorpyrifos-e (n=9) with an average concentration of 0.24±0.38 pmol/m3 and Phosmet (n=10) with an average concentration 0.24±0.45 pmol/m3; Diazinon was detected in 4 samples with average concentration 0.07±0.00 pmol/m3. Less abundant but with higher concentration was the chlorpyrifos-me (n=3) with average concentration 0.91±0.93 pmol/m3. Ethoprophos was detected only in one sample (0.002 pmol/m3), Malathion was not detected. The average contribution of organophosphate pesticides in atmospheric organic P detected in this study was 0.2%.
The organophosphorus flame retardants and plasticizers (OPEs) are widely employed in industrial applications and household products. Some OPEs have been reported to be persistent in the environment and to bio-accumulate in the food chain. In addition, some halogenated OPEs have been found to exhibit various toxic effects. During this study were analysed six different OPEs compounds: TCPP(mix isomers), TCPP, TDCP, TnBP, TPhP, EHDP. In Table 2 (Fig. 1a) are presented the average atmospheric concentrations of OPEs measured during this study. It is remarkable that all OPEs compound presented high concentrations in West Med., especially the most potentially hazardous (TCPP, TCEP, TDCP). The percentage contribution of OPEs in atmospheric organic-P over West Med. was 9%, while over East was just 0.5%.
The atmospheric organic P compounds of biological origin detected during PHOSPHOTRAC were the phospholipids: phosphatidylcholine (PC), Phosphatidylglycerol (PG) and phosphatidylethanolamine (PE) and ATP-like compounds. Phytic acid was not detected. PC is usually the most abundant phospholipid in animals and plants, often amounting to almost 50% of the total complex lipids, while it is less often found in prokaryotic cells. Preliminary results on phospholipids showed that PC was the predominant phospholipid with an average concentration of 14.1±47.2 pmol/m3, following by PG with an average concentration of 2.3±10.2 pmol/m3, with contribution to TP of 2% and 0.2%, respectively. Negligible was the contribution of PE. It is remarkable that during a dust event the concentration levels of PC and PG were increased 20 and 30 times, respectively, suggesting that the high number of cells delivered by the dust contribute significantly to the atmospheric organic P pool (Fig.1). Furthermore, the ATP-like compounds analysed were ATP (Adenosine TriPhosphate) which is a key molecule of the energetic cell metabolism, ADP (Adenosine DiPhosphate) and AMP (Adenosine MonoPhosphate). Only the AMP was detected in 27% of the total samples; with the average concentration of 0.06±0.10 pmol/m3, while during a dust event the concentration was increased five times.
