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首页> 外文期刊>Environmental Science: Processes & Impacts >Passive sampling of DDT, DDE and DDD in sediments: accounting for degradation processes with reaction-diffusion modeling
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Passive sampling of DDT, DDE and DDD in sediments: accounting for degradation processes with reaction-diffusion modeling

机译：沉积物中DDT，DDE和DDD的被动采样：核算反应扩散建模的降解过程

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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 C-13 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 (C-13-labeled PCBs, C-13-labeled DDE and DDD). The DDT PRC loss was also accompanied by accumulation in the PE of its degradation product, C-13 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.
机译：被动采样正在成为评估环境介质中自由溶解浓度​​的疏水有机污染物的应用工具。对于某些媒体和目标分析物，达到平衡的时间超过部署时间，并且在这种情况下，在部署之前，在采样器中加载的性能参考化合物（PRC）是用于评估分数的常见方法之一。靶分析物的平衡。使用中华人民共和国背后的关键假设是他们的释放是单独扩散驱动的。但在这项工作中，我们表明沉积物中的中国转换可以对中国的释放产生可测量的影响，甚至允许估计该化合物在感兴趣的环境中的转变率。我们发现，与其他PRC的丧失相比，在沉积物 - 水界面中展开的聚乙烯（PE）被动采样器中，从沉积物 - 水界面的聚乙烯（PE）被动采样器的损失加速了（C -13标记的PCB，C-13标记的DDE和DDD）。 DDT PRC损耗还伴随着其降解产物的PE积累，C-13 2,4'-DDD。使用1D反应扩散模型，我们从测量的PRC损耗推导出DDT的原位降解速率。原位降解速率随深入的深度增加到沉积物床（0-10cm，1.4d（-1），在30-40cm），虽然它们无法独立验证，但这些速率有利地比较具有文学价值。 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.更重要的是，这项工作开辟了新颖的被动采样器的新应用的机会，特别是关于调查原位降解率，途径和遗产污染物的途径和产品。然而，需要进一步的工作来证实，从PRC损失的模型拟合推导出来的速率是沉积物中DDT转化率的真正反映。

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