engleski

Organochlorine pesticides and polychlorinated biphenyls in atmospheric fine particles collected in Zagreb over ten years

Organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) belong to a group of widespread, highly persistent, lipophilic, and semivolatile environmental micropollutants. They can be transported over long distances by circulation of air masses, precipitation of particles onto which pollutants are sorbed, and by wet depositions washing them out from the atmosphere. Their sorption to airborne inhalable particles with an equivalent aerodynamic diameter of <10 μm (PM10) and respirable particles with an equivalent aerodynamic diameter of <2.5 μm (PM2.5) is of special concern because particle toxicity varies not only with size but also with chemical composition. We studied the occurrence and levels of OC pesticides (hexachlorobenzene, alpha-, beta-, and gamma-hexachlorocyclohexane, 4, 4'-DDT, 4, 4'-DDE, 4, 4'-DDD) and 20 PCB congeners (six indicator congeners: PCB-28, PCB-52, PCB-101, PCB- 138, PCB-153, and PCB-180, and fourteen other toxicologically significant congeners: PCB-60, PCB-74, PCB-77, PCB-105, PCB-114, PCB-118, PCB- 123, PCB-126, PCB-156, PCB-157, PCB-167, PCB-169, PCB-170, and PCB-189) in PM10 and/or PM2.5 samples collected daily from October 2000 to December 2003, from January to March 2010, and from June to July 2010 at a site in the northern residential part of Zagreb. Twenty-four-hour samples of particle fractions were collected on one or two glass or quartz microfibre filters in parallel, from approximately 100 m^3 of ambient air per filter at the average air flow rate of 70 L/min. Filters with particle samples collected over seven consecutive days were combined for chemical analysis. The collection and analysis of seven-day air samples instead of seven combined 24-hour samples failed because of considerable volatilisation losses leading to an underestimation of particle-bound micropollutants. OC compounds associated with particles were accumulated by ultrasonic extraction with 1:1 acetone:n-hexane mixture. The extracts were purified with sulphuric acid and analysed using high resolution gas chromatography with electron capture detection. In the monitored ten-year period, mass concentrations of OC compounds in fine particles in air (pg/m^3) were characteristic of global environmental pollution. Their abundance and concentrations in PM2.5 and PM10.5 particle fractions did not significantly differ, which suggests that they were mainly sorbed in the respirable PM2.5 fraction. A local input was observed only for gamma-HCH, but a decrease in its environmental levels might be expected, since lindane has been banned for use in agriculture and forestry in Croatia since 2005. This study showed no pronounced seasonal variations in the concentrations of particles carrying any OC compound. A decreasing trend in the mass concentrations of beta-HCH, 4, 4‘-DDE, 4, 4‘-DDT, PCB-138, PCB-153, and PCB-180 with increasing air temperature may be related to lower fine particles mass concentrations at higher temperatures, and, consequently, to less OC particle-bound compounds in the atmosphere.

organochlorine pesticides ; polychlorinated biphenyls ; inhalable particles PM10 ; respirable particles PM2.5

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