Sampling rates for passive samplers exposed to a field-relevant peak of 42 organic pesticides

Evaluation of Chemcatcher® passive samplers for pesticide monitoring using high-frequency catchment scale data

“…However, the majority of TWMC PS values were within a factor of two of the TWMC HFS values, which is in agreement with studies in other rivers ( Moschet et al, 2015 ; Townsend et al, 2018 ) and lab studies ( Schreiner et al, 2020 ; Shaw and Mueller, 2009 ). Additionally, the general linearity of the relationship between TWMC PS and TWMC HFS values, albeit with only MCPA concentrations being on the 1:1 Line ( Fig.…”

Paradise lost? Pesticide pollution in a European region with considerable amount of traditional agriculture

“…A previous study showed that using this approach calculated concentrations from passive samplers matched well with concentrations based on event-driven samplers (Fernández et al, 2014). When using the whole exposure duration, of passive samplers, however, calculated concentrations from passive sampling were lower in contrast to event-driven samples or the maximum concentration (Bundschuh et al, 2014;Schreiner et al, 2020).…”

“…where m sorb is the mass of the pesticide i accumulated on the disk or the sheet, R i is the respective sampling rate (L day -1 ; Table S2) and t is the assumed uptake time in days into the receiving phase. Given that most of the pesticide mass sorbed to a disk during peak exposure samples originates from the peak, we set the uptake time to the estimated peak duration of two days to calculate the peak concentration for rainfall event samples (Schreiner et al, 2020). For base flow samples, we used the whole deployment period (here t = 6), assuming relatively constant exposure and consequently sorption (for discussion see below).…”

“…First, flow velocity, below 0.2 m s -1 , is known to have a strong effect on sampling rates (Booij et al, 2016, Moschet et al, 2015Vermeirssen et al, 2008), even though this effect can be masked by other factors like water matrix or different analytical methods (Schreiner et al, 2020). Since sampling rates across studies seem to be independent of the flow velocity over a range of 0.1 and 0.9 m s -1 (Schreiner et al, 2020), we consider flow velocity differences between the determination of sampling rates and the deployment of passive samplings as minor. Nonetheless, in four sites the flow velocities were below 0.2 m s -1 during either deployment or retrieval (min.…”

“…Based on this we calculated peak concentrations for the SDB disks from peak exposure samples (Table S3) using an estimated peak duration of two days (t = 2, equation 1). A previous study showed that the calculated peak concentrations using this approach may approximate 50 % of the maximum concentration (Schreiner et al, 2020). For the PDMS sheets, we used a time span corresponding to their exposure time, because they were independent of pulses associated with rainfall events.…”