Passive sampling of DDT, DDE and DDD in sediments: accounting for degradation processes with reaction-diffusion modeling
| Autor: | Philip M. Gschwend, Raffaella Borrelli, A. Patricia Tcaciuc, Luciano M. Zaninetta |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
China
Dichlorodiphenyldichloroethane Geologic Sediments animal structures 010504 meteorology & atmospheric sciences Dichlorodiphenyl Dichloroethylene Soil science 010501 environmental sciences Management Monitoring Policy and Law 01 natural sciences DDT Diffusion Reaction–diffusion system Environmental Chemistry Diffusion (business) Environmental Restoration and Remediation 0105 earth and related environmental sciences Deployment time Public Health Environmental and Occupational Health Sediment Membranes Artificial General Medicine Contamination Models Theoretical Polyethylene Environmental science Degradation (geology) Hydrophobic and Hydrophilic Interactions Water Pollutants Chemical Passive sampling In situ degradation Environmental Monitoring |
| Zdroj: | Environmental science. Processesimpacts. 20(1) |
| ISSN: | 2050-7895 |
| Popis: | Passive sampling is becoming a widely used tool for assessing freely dissolved concentrations of hydrophobic organic contaminants in environmental media. For certain media and target analytes, the time to reach equilibrium exceeds the deployment time, and in such cases, the loss of performance reference compounds (PRCs), loaded in the sampler before deployment, is one of the common ways used to assess the fractional equilibration of target analytes. The key assumption behind the use of PRCs is that their release is solely diffusion driven. But in this work, we show that PRC transformations in the sediment can have a measurable impact on the PRC releases and even allow estimation of that compound's transformation rate in the environment of interest. We found that in both field and lab incubations, the loss of the 13C 2,4′-DDT PRC from a polyethylene (PE) passive sampler deployed at the sediment–water interface was accelerated compared to the loss of other PRCs (13C-labeled PCBs, 13C-labeled DDE and DDD). The DDT PRC loss was also accompanied by accumulation in the PE of its degradation product, 13C 2,4′-DDD. Using a 1D reaction–diffusion model, we deduced the in situ degradation rates of DDT from the measured PRC loss. The in situ degradation rates increased with depth into the sediment bed (0.14 d−1 at 0–10 cm and 1.4 d−1 at 30–40 cm) and although they could not be independently validated, these rates compared favorably with literature values. This work shows that passive sampling users should be cautious when choosing PRCs, as degradation processes can affect some PRC's releases from the passive sampler. More importantly, this work opens up the opportunity for novel applications of passive samplers, particularly with regard to investigating in situ degradation rates, pathways, and products for both legacy and emerging contaminants. However, further work is needed to confirm that the rates deduced from model fitting of PRC loss are a true reflection of DDT transformation rates in sediments. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|