Simulating the spread of disinfection by-products and anthropogenic bromoform emissions from ballast water discharge in Southeast Asia
Simulating the spread of disinfection by-products and anthropogenic bromoform emissions from ballast water discharge in Southeast Asia
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DOI：
10.5194/os-15-891-2019
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发表时间：
2019-07
期刊：
影响因子：
3.2
通讯作者：
Josefine Maas;S. Tegtmeier;B. Quack;A. Biastoch;Jonathan V. Durgadoo;S. Rühs;S. Gollasch;M. David
中科院分区：
文献类型：
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作者：
Josefine Maas;S. Tegtmeier;B. Quack;A. Biastoch;Jonathan V. Durgadoo;S. Rühs;S. Gollasch;M. David
抽象的。船舶需要进行压载水处理，以防止引入潜在的侵入性新生物群。一些处理方法使用化学消毒剂，这些消毒剂会产生多种卤化化合物作为消毒副产物（DBP）。氧化压载水处理中最丰富的 DBP 之一是三溴甲烷 (CHBr3)，根据测量和文献，我们发现未稀释压载水中的平均浓度为 894±560 nmol L−1 (226±142 µg L−1)。三溴甲烷是一种与大气化学和臭氧消耗相关的气体，特别是在可能夹带进入平流层的热带地区。本文首次评估了 DBP 在热带地区数月至数年的传播情况。利用基于 NEMO-ORCA12 模型速度场的拉格朗日轨迹，我们模拟了 DBP 在海面的扩散，并量化了海洋三溴甲烷浓度以及东南亚热带地区主要港口压载水排放到大气中的排放量。对新加坡和珠江三角洲这两个重要地区的示范性模拟揭示了 DBP 和人为三溴甲烷在海面浓度的主要传输途径。根据我们的模拟，我们预计 DBP 将沿着海岸扩散到公海，并通过季风驱动的平流进入北太平洋和印度洋。此外，预计大型港口周围的人为三溴甲烷浓度和排放量将会增加。在新加坡周围的海面上，我们估计三溴甲烷浓度比最近的测量值增加了 9%。在 70% 的压载水经过化学处理的温和情况下，向大气中排放的三溴甲烷局部可能超过 1000 pmol m−2 h−1 ，是气候排放的两倍。在珠江三角洲，所有三溴甲烷都直接排出，这导致额外的溴 (Br) 输入到大气中，含量为 495 kmol Br a−1 (∼42 t CHBr3)。对于新加坡港口，额外的大气 Br 输入计算为 312 kmol Bra−1 (∼ 26 t CHBr3)。我们估计全球从压载水进入大气的人为溴输入量高达 13 Mmol a−1。这是来自背景三溴甲烷排放的全球溴输入的 0.1%，因此与平流层臭氧消耗无关。
Abstract. Ballast water treatment is required for vessels to prevent the introduction of potentially invasive neobiota. Some treatment methods use chemical disinfectants which produce a variety of halogenated compounds as disinfection by-products (DBPs). One of the most abundant DBPs from oxidative ballast water treatment is bromoform (CHBr3), for which we find an average concentration of 894±560 nmol L−1 (226±142 µg L−1) in the undiluted ballast water from measurements and the literature. Bromoform is a relevant gas for atmospheric chemistry and ozone depletion, especially in the tropics where entrainment into the stratosphere is possible. The spread of DBPs in the tropics over months to years is assessed here for the first time. With Lagrangian trajectories based on the NEMO-ORCA12 model velocity field, we simulate DBP spread in the sea surface and quantify the oceanic bromoform concentration and emissions to the atmosphere from ballast water discharge at major harbours in the tropical region of Southeast Asia. The exemplary simulations of two important regions, Singapore and the Pearl River Delta, reveal major transport pathways of DBPs and anthropogenic bromoform concentrations in the sea surface. Based on our simulations, we expect DBPs to spread into the open ocean, along the coast and through advection with monsoon-driven currents into the North Pacific and Indian Ocean. Furthermore, anthropogenic bromoform concentrations and emissions are predicted to increase locally around large harbours. In the sea surface around Singapore, we estimate an increase in bromoform concentration by 9 % compared to recent measurements. In a moderate scenario in which 70 % of the ballast water is chemically treated, bromoform emissions to the atmosphere can locally exceed 1000 pmol m−2 h−1 and double climatological emissions. In the Pearl River Delta all bromoform is directly outgassed, which leads to an additional bromine (Br) input into the atmosphere of 495 kmol Br a−1 (∼42 t CHBr3). For Singapore ports the additional atmospheric Br input is calculated as 312 kmol Br a−1 (∼ 26 t CHBr3). We estimate a global anthropogenic Br input from ballast water into the atmosphere of up to 13 Mmol a−1. This is 0.1 % of global Br input from background bromoform emissions and thus not relevant for stratospheric ozone depletion.