State Key Laboratory of Marine Environmental Science, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China; Department of Environmental Sciences, University of California, Riverside, CA 92521, United States.
Southern California Coastal Water Research Project Authority (SCCWRP), Costa Mesa, CA 92626, United States.
Sci Total Environ. 2017 Dec 1;599-600:364-371. doi: 10.1016/j.scitotenv.2017.05.022. Epub 2017 May 4.
The coupling of disposable solid-phase microextraction (SPME) with performance reference compounds (PRCs) has been recently introduced to measure time-averaged freely dissolved concentrations (C) of hydrophobic organic contaminants in sediments under laboratory conditions. To explore the use of PRC-SPME for in situ sampling in seawater, disposable PDMS fibers (35-μm and 100-μm coating) preloaded with stable isotope labeled analogues as PRCs were deployed at six stations (each with three depths) in the open ocean of the Palos Verdes Shelf (CA, USA) Superfund site for 33d to measure C of DDT and its degradates. The observed values of fractional equilibration (f) of PRCs were mostly <0.85, suggesting nonequilibrium conditions at the end of deployment. The observed fs for the samplers varied with compound, sampling station and depth, validating the need for calibration to derive accurate C. The C values of DDE and DDD determined with PRC-SPME were in good agreement with those previously measured by in situ large-volume water sampling or polyethylene devices. The highest C in seawater 5m off the ocean floor was 750pgL for o,p'-DDE, 2170pgL for p,p'-DDE, 24pgL for o,p'-DDD, and 75pgL for p,p'-DDD. Results of this study demonstrated the feasibility and advantages of using disposable PDMS fiber coupled with PRCs for in situ sampling.
一次性固相微萃取（SPME）与性能参考化合物（PRC）的偶联最近被引入到实验室条件下测量沉积物中疏水性有机污染物的时间平均自由溶解浓度（C）。为了探索 PRC-SPME 在海水中原位采样的应用，在帕洛斯弗迪斯架（CA，美国）超级基金场地的开阔海域的六个站位（每个站位有三个深度）部署了预先加载有稳定同位素标记类似物作为 PRC 的一次性 PDMS 纤维（35-μm 和 100-μm 涂层），以测量滴滴涕及其降解产物的 C。PRC 的分数平衡（f）的观测值大多<0.85，表明在部署结束时处于非平衡状态。采样器的观测 fs 值随化合物、采样站位和深度而变化，这验证了需要进行校准以得出准确的 C 的必要性。用 PRC-SPME 确定的 DDE 和 DDD 的 C 值与先前通过原位大体积水样采集或聚乙烯装置测量的值吻合较好。距海底 5m 的海水中的最高 C 值为 o,p'-DDE 的 750pgL，p,p'-DDE 的 2170pgL，o,p'-DDD 的 24pgL 和 p,p'-DDD 的 75pgL。这项研究的结果表明，使用一次性 PDMS 纤维与 PRC 偶联进行原位采样是可行的，并且具有优势。
