Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-Cho, Matsuyama 790-8577, Japan.
Center for Marine Environmental Studies, Ehime University, 2-5 Bunkyo-Cho, Matsuyama 790-8577, Japan.
Environ Sci Technol. 2022 Sep 6;56(17):12307-12314. doi: 10.1021/acs.est.2c03459. Epub 2022 Aug 15.
Calculating accurate air-sea fluxes for polychlorinated biphenyls (PCBs) is an essential condition for evaluating their transport in the atmosphere. A three-dimensional hydrodynamic-ecosystem-PCB coupled model was developed for the northwestern Pacific Ocean to assess the air-sea fluxes of four PCBs and examine the influences of ocean currents on the fluxes. The model revealed a fine structure in the air-sea flux that is sensitive to the Kuroshio, a western boundary current with a high surface speed. Intense downward and upward fluxes (-23.6 to 44.75 ng m d for ∑PCBs) can be found in the Kuroshio region south of Japan and the Kuroshio Extension east of Japan, respectively. In strong (weak) current regions, it takes ∼4 and ∼1 days (1-3 and 3-12 days) for dissolved PCBs to reach an equilibrium in scenarios where only air-sea exchange or only ocean advection is considered, respectively. In strong current regions, the ocean advection has a shorter response time than the air-sea exchange, indicating that dissolved PCBs from upstream carried by strong current can easily change the downstream concentration by disrupting the equilibrium with original air-sea exchange and induce new air-sea fluxes there. Therefore, strong western boundary currents should be correctly considered in future atmospheric transport models for PCBs.
准确计算多氯联苯（PCBs）的大气-海洋通量是评估其在大气中传输的必要条件。为西北太平洋开发了一个三维水动力-生态系统-PCB 耦合模型，以评估四种 PCB 的大气-海洋通量，并研究海流对通量的影响。该模型揭示了大气-海洋通量的精细结构，对具有高表面速度的西边界流黑潮很敏感。在日本南部的黑潮区和日本东部的黑潮延伸区，可以发现强烈的向下和向上通量（∑PCBs 为-23.6 到 44.75ngm-2d-1）。在强（弱）流区，当仅考虑大气-海洋交换或仅海洋平流时，溶解态 PCBs 达到平衡所需的时间分别约为 4 天（1-3 天）和 1 天（3-12 天）。在强流区，海洋平流的响应时间比大气-海洋交换短，这表明由强流携带的上游溶解态 PCBs 可以通过破坏与原始大气-海洋交换的平衡并在下游引起新的大气-海洋通量，从而容易改变下游浓度。因此，在未来的 PCB 大气传输模型中，应正确考虑强西边界流。
