Unique calibration of passive air sampling for field monitoring of PAHs with polyethylene thin films across seasons and locations

Abstract

Although passive sampling has been applied to determine concentrations of semi-volatile organic chemicals such as polycyclic aromatic hydrocarbons (PAHs) in air and water for about two decades and is well...

Comprehensive Multi-compartment Sampling for Quantification of Long-Term Accumulation of PAHs in Soils

“…Integration over half a year naturally leads to a loss of dynamics within this exchange process and thus adds some uncertainty especially for the LMW PAHs (Fln and Phe). In a previous study, we show that the average atmospheric concentrations remain relatively stable throughout seasons (comparing May and August, as well as November and February) during two consecutive years . For the soils, the ex situ batch experiment illustrates quite slow desorption kinetics, which exceed 4 months to equilibrate.…”

“…Seasonal variations of organic pollutants in the atmosphere (or the vegetation layer above the ground) have been related to plants and plant growth as a buffering effect by numerous studies. ,,, Thomas et al and Gouin et al observe a decrease of atmospheric PCB concentrations simultaneous to an increase of biomass, and Liu et al measure a decrease of PAHs in air during the growing season. In our earlier study, no indication of such a scavenging effect could be observed and instead atmospheric concentrations were rather stable during the growing season (May to August). Consequently, in the present study, the seasonal variation of PAH concentrations in air and the concentration gradient across the soil–atmosphere interface can mostly be explained by changing temperature as well as primary emission rates due to increased combustion during the cold season. ,,, …”

“…In our earlier study, no indication of such a scavenging effect could be observed and instead atmospheric concentrations were rather stable during the growing season (May to August). Consequently, in the present study, the seasonal variation of PAH concentrations in air and the concentration gradient across the soil–atmosphere interface can mostly be explained by changing temperature as well as primary emission rates due to increased combustion during the cold season. ,,, …”

“…, in summer). Since the HMW PAHs (Fth and Pyr) do not reach equilibrium during the deployment, concentrations were extrapolated for equilibrium conditions ( C p,eq ) using a first-order model (for details, see ref ). Passive sampling excludes the particle-associated fraction in the atmosphere, which has a relevant contribution to soil deposition of high molecular weight PAHs. ,,, Therefore, we additionally sampled the atmospheric bulk deposition at the monitoring locations.…”

“…The unit-equivalent coefficient K Fr * may be applied for a whole range of similar target compounds such as various PAHs if parameters for one representative are known. Incorporating K Fr * into eq 4b to calculate the soil air concentration (at equilibrium) for all target PAHs leads to For higher molecular weight compounds (Fth and Pyr), which remain in the linear uptake phase during the monitoring period, a numerical model was applied to extrapolate the measured concentrations on the sampler to equilibrium conditions, as shown in detail in Meierdierks et al 47 Similarly, the sampler−water partition coefficient K pw [L/kg] and H [-] may be used to calculate the concentration in soil air…”