Temporal variability measurements of PM 2.5 and its associated metals and microorganisms on a suburban atmosphere in the central Iberian Peninsula.

A novel and multidisciplinary observational analysis of atmospheric components in the Central Iberian Peninsula is presented here. PM _2.5 concentrations and both populations of cultivable and non-cultivable microorganisms and concentrations of a wide range of trace elements associated have been simultaneously studied during multiple events along one year. The aim has been to characterize their potential relations and dependencies, and their seasonal, daily and hourly evolution. Tools that could explain the atmospheric mechanisms and sources from all these elements have been also evaluated. As it would be expected from a suburban environment, absolute levels obtained were not close to legislation limits. Anthropogenic and natural sources, such as heating home, soil resuspension, or Sahara dust intrusion; and atmospheric factors are responsible for higher PM _2.5 and metals concentrations in months with both low and high temperatures. Daily and hourly evolution depends on University Campus activity, especially on traffic flow and resuspended dust due to human transit. No statistical significant differences on daily or seasonal scales between cultivable counts of fungi and bacteria were displayed. However, using the q-PCR technique, the bacterial population was lower in winter. Positive correlations between PM _2.5 and relative humidity; and PM _2.5 and cultivable microorganism have been established. It was also the case among 7 of the 11 trace elements, indicating then common natural or anthropogenic sources. In summary, this work illustrates the interest of a combined inspection of elements, interactions and dependencies when studying the unique and continuous atmospheric environment, which are typically analysed separately.
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