Arsenic and antimony speciation in atmospheric particulate matter of Andalusia

Resumen

A new method for Sb extraction in PM samples has been developed, based on the use of microwave radiation (operated at 90 W during 3-6 min) with a 0,05 mol L1 NEhOH-HCl solution. The analysis of the extracts was performed by coupling high performance liquid chromatography (HPLC), hydride generation (HG) with atomic fluorescence spectrometry (AFS). Extraction by microwave radiation was compared to ultrasound probe extraction. The proposed extraction method for Sb spéciation in atmospheric particulate matter based on microwave extraction represents a suitable alternative to ultrasound probe extraction. Overall, the extraction time with microwave radiation is in the same range as the ultrasound probe, although a little bit longer (6 min compared to reported 3 min). The proposed extraction method has been applied to PM 10 samples of Cordoba and Granada, collected from 4 monitoring stations of different categories: one corresponds to urban background (Lepanto station in Cordoba), two to traffic influence (Alnasir station in Cordoba and Granada Norte in Granada) and one to industrial influence (Parque Joyero station in Cordoba). The results obtained showed that Sb spéciation can be a useful geochemical tracer to identify anthropogenic sources. It has been performed a thorough revision of the state of the art of As in atmospheric particulate matter, considering analytical steps such as sampling, sample treatment, and analysis of both total and spéciation at different particle size has been performed. Sample digestion of the collecting media of PM for total As has been described, indicating proposed and established procedures that use acids or mixtures of acids aided with different heating procedures. For As spéciation, mild aqueous extractants are employed, usually in a single extraction step, although sequential extraction procedures have been also described. The connnon procedure for As spéciation analysis is the combination of a separation teclmique (HPLC and to a minor extend also GC) with atomic spectroscopy detectors (AAS, AFS and ICP-OES) or mass spectrometry (ICP-MS). Intermediate steps that use hydride generation or cold trap are also employed in As spéciation analysis. A study about the air quality of Huelva, located nearby on the largest Cu-smelter in Europe, has been performed for the period 2001-2015, The trends of SO2 and geochemical pattern ofPM2.5 andPMlO were studied. Three periods were selected: prior (2001-2008), during (2009-2013) and after (2014-2015) the implementation of emission abatement technology (wet electrofilters, bag filters and lime injection) by this large industrial facility. A high As concentration is the main geochemical anomaly in PM of Huelva. In the period 2001-2008, prior to the implementation of current high efficient emission controls in this industry, high levels of sulphide-related elements (As, Se, Cd , Sn, Pb and Bi ) were recorded, which resulted in the repeatedly exceedances of the EU amiual target value of As concentration of 6 ng m"3. In the latest period 2014-2015, a -50% reduction or higher was observed for these elements, which in the case of As resulted in mean concentration of 2.8 ng nr3 in PM 10. A similar behavior was observed for PM2.5 samples. However, there are still sporadic (less intensity) As and SO2 pollution episodes. Furthermore, As spéciation analysis ofPMlO andPM2.5 samples with HPLC-HG-AFS has point out that As is present mainly as As(V) (>90%) in relation to As(III) (<10%). The trend in the studied period indicates a, reduction in the proportion of As(V) in PM 10 from 97% in 2010 to 90% in 2014. This reduction in the percentage of As(V) is due to a decrease of the concentration of As(V), not to an increment of As(III). Nevertheless, episodes with a high As(III) proportion are still registered.