Watershed Assessment Branch, Delaware Department of Natural Resources and Environmental Control, 820 Silver Lake Boulevard, Suite 220, Dover, Delaware 19904, United States.
Environ Sci Technol. 2013 Jun 18;47(12):6408-14. doi: 10.1021/es400817c. Epub 2013 May 28.
High volume in situ surface water samples were collected from a tidal tributary of the Delaware Estuary using an Infiltrex sampling system equipped with a 1 μm particle filter and a XAD-2 resin column. Particulate and dissolved phase polychlorinated biphenyl (PCB) congeners were analyzed using high resolution gas chromatography/high resolution mass spectrometry to obtain detection levels in the femtograms per liter range. The data were fit to a four-phase equilibrium partitioning model including freely dissolved PCB, PCB bound to particulate organic carbon (POC), PCB bound to dissolved organic carbon (DOC), and PCB bound to black carbon (BC). Isotherms were assumed to be linear for POC and DOC and nonlinear for BC. The partition coefficient between BC and dissolved PCB was assumed to depend on the dihedral angle between the phenyl rings. Following parameter optimization, the correlation coefficient between the log of the modeled and measured apparent distribution coefficient Kp,app was 0.94, and the RMSE was 0.189 log units. Including BC in the model reduces the dissolved PCB phase concentration in the water column for all congeners, especially for the non-ortho and mono-ortho substituted congeners.
采用配备有 1μm 颗粒过滤器和 XAD-2 树脂柱的 Infiltrex 采样系统，从特拉华河口的一条潮汐支流中采集了大量原位地表水样品。使用高分辨率气相色谱/高分辨率质谱法分析了颗粒相和溶解相多氯联苯（PCB）同系物，以获得纳克每升级别的检测水平。数据符合包括自由溶解 PCB、与颗粒有机碳（POC）结合的 PCB、与溶解有机碳（DOC）结合的 PCB 和与黑碳（BC）结合的 PCB 的四相平衡分配模型。假设 POC 和 DOC 的等温线是线性的，而 BC 的等温线是非线性的。BC 和溶解 PCB 之间的分配系数被假设取决于苯环之间的二面角。在进行参数优化后，模型预测的和实测的表观分配系数 Kp，app 的对数之间的相关系数为 0.94，RMSE 为 0.189 对数单位。在模型中包含 BC 会降低所有同系物在水柱中的溶解 PCB 相浓度，特别是对于非邻位和单邻位取代的同系物。
