| A new grab sample method is presented that uses a conventional sorbent (XAD-2) followed in series by an anion-exchange resin (Amberlyst A21) for the separate recovery of truly dissolved hydrophobic organic contaminants (HOCs) and HOCs bound to dissolved organic matter (DOM). This method is applied for the field calibration of PISCES (Passive In-Situ Concentration/Extraction Sampler) in Onondaga Lake, Syracuse, NY. The observed average, compound-independent sampling rate was 0.081 +/- 0.037 L d-1 cm-2 of membrane area or 4.1 +/- 1.8 L d-1 for the specific sampler used. The weekly sampling rates demonstrated minor temperature dependence that is unlikely to influence the measurement of time-weighted average (TWA) concentrations within the observed temperature range. Using the field-determined sampling rate in 2009-10, PISCES successfully captured short-term HOC fluctuations as well as long-term seasonal and decadal HOC changes, including a 5-10 fold decrease in dichlorobenzenes and 5-fold decrease in naphthalene since 1994. |
