Measurement-based modeling of bromine chemistry in the boundary layer: 1. Bromine chemistry at the Dead Sea
Measurement-based modeling of bromine chemistry in the boundary layer: 1. Bromine chemistry at the Dead Sea
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基于测量的边界层溴化学建模：1. 死海的溴化学
DOI：
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发表时间：
2006
期刊：
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通讯作者：
M. Luria
中科院分区：
文献类型：
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作者：
E. Tas;M. Peleg;Daniel U. Pedersen;V. Matveev;A. Biazar;M. Luria
死海是研究活性溴（RBS）化学的绝佳天然实验室，因为在该地区观察到的RBS水平较高，再加上人为空气污染物高达数ppb。本研究采用一维数值化学模型研究了死海RBS的基本化学机制。模拟是根据在死海沿着地点进行的全面测量所获得的数据进行的。模拟结果表明，在死海经常测得的高BrO水平只能部分归因于死海水中存在的高浓度Br。此外，死海的RBS活动不能仅用纯气相机制来解释。本文提出了一种化学机制，它可以解释在死海观测到的化学活动，只有两个非均相过程：“溴爆炸”机制和BrONO2的非均相分解。在死海蒸发池中，臭氧经常低于1至2 ppbv的阈值，在这种情况下，O3成为BrOx（BrO+Br）生产的限制因素。O_3通量被带入蒸发池是RBS活动持续的埃森条件，也是造成死海地区BrO日变化呈锯齿状以及在低O_3浓度下BrO与O_3呈正相关的主要原因。目前的研究表明，BrONO2的多相分解有很大的潜力，影响RBS活动的人为排放的影响，主要是由于该过程的速率和NO2的水平之间的正相关性。进一步调查的影响，分解的溴酸盐可能是特别重要的了解RBS活动在中纬度地区。
The Dead Sea is an excellent natural laboratory for the investigation of Reactive Bromine Species (RBS) chem- istry, due to the high RBS levels observed in this area, com- bined with anthropogenic air pollutants up to several ppb. The present study investigated the basic chemical mechanism of RBS at the Dead Sea using a numerical one-dimensional chemical model. Simulations were based on data obtained from comprehensive measurements performed at sites along the Dead Sea. The simulations showed that the high BrO lev- els measured frequently at the Dead Sea could only partially be attributed to the highly concentrated Br present in the Dead Sea water. Furthermore, the RBS activity at the Dead Sea cannot solely be explained by a pure gas phase mecha- nism. This paper presents a chemical mechanism which can account for the observed chemical activity at the Dead Sea, with the addition of only two heterogeneous processes: the "Bromine Explosion" mechanism and the heterogeneous de- composition of BrONO2. Ozone frequently dropped below a threshold value of 1 to 2 ppbv at the Dead Sea evapora- tion ponds, and in such cases, O3 became a limiting factor for the production of BrOx (BrO+Br). The entrainment of O3 fluxes into the evaporation ponds was found to be essen- tial for the continuation of RBS activity, and to be the main reason for the jagged diurnal pattern of BrO observed in the Dead Sea area, and for the positive correlation observed be- tween BrO and O3 at low O3 concentrations. The present study has shown that the heterogeneous decomposition of BrONO2 has a great potential to affect the RBS activity in areas influenced by anthropogenic emissions, mainly due to the positive correlation between the rate of this process and the levels of NO2. Further investigation of the influence of the decomposition of BrONO2 may be especially important in understanding the RBS activity at mid-latitudes.