A one-year survey of organotin compounds in the reservoirs supplying the drinking water treatment plants of Athens, Greece

Organotin compounds belong to the priority list of substances regulated by 76/464/EEC Directive, as well as by 2000/60/EC Water Framework Directive, because they pose considerable risks to the environment and human health. They are the most commonly used organometallic compounds with estimated global amount produced 50,000 tons per year. Therefore, they have been detected worldwide in surface waters, drinking water, sediments and biota. The objective of the present investigation was the determination of these compounds in the water sources supplying the drinking water treatment plants of Athens, Greece, in particular at the reservoirs Mornos, Marathonas, Yliki and Evinos. The quality of water of those reservoirs could be affected from human activities, such as industry and agriculture, as well as from settlements in the area nearby. The surface water sampling campaigns executed were seasonal, during the period March 2004–May 2005, while finished drinking water samples from the distribution network of Athens were also analyzed. Six organotin species (monobutyltin, dibutyltin, tributyltin, monophenyltin, diphenyltin and triphenyltin) were determined by a gas chromatography — flame photometric detector (GC-FPD) method, after sample pretreatment with simultaneous liquid–liquid extraction with hexane and derivatization with tetraethyl borate. The results showed that the waters studied are free from organotin compounds, except for a limited number of samples, where the occurrence of some organotin species at low concentrations was observed.

The occurrence of OTs was investigated in the reservoirs supplying the water treatment plants of Athens through seasonal sampling campaigns for a period of one year. The results have shown that the overall pollution status of the water bodies of the area of Attiki is very low regarding the OTs. The concentrations detected were comparable to or lower than those reported for surface waters in the literature. The presence of DBT, TBT, DPT and TPT in the waters studied, in a limited number of cases, could be attributed to agricultural activities, waste disposal and some limited industrial activity in the settlements nearby the water bodies. The analyses of sediment samples in the area could provide more insight regarding the possibility of OTs adsorption and remobilization. In the tap water samples from the distribution network (Menidi area), OTs concentrations were not detectable. Although DPT and TPT were present in Menidi raw water during one of the sampling campaigns, probably they were removed by adsorption to particulate matter during the water treatment procedure.