Study on sulfur dioxide transport from China to Japan using an advection and dispersion model
Study on sulfur dioxide transport from China to Japan using an advection and dispersion model
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发表时间：
2009
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通讯作者：
Suzuki;S. Watanabe;M. Hasebe;S. Matsuda
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作者：
Suzuki;S. Watanabe;M. Hasebe;S. Matsuda
本文利用Draxler等人开发的混合单粒子拉格朗日积分轨迹模型HYSPLIT4对冬季中国输往日本的酸性物质二氧化硫的一系列输送过程进行了数值模拟。该模型假定材料可以用颗粒或喷雾(或两者兼有)来表示，并基于拉格朗日方法计算了它们的平流、扩散和沉积过程。本研究基于三种情景进行了实验模拟，以了解冬季大陆中国排放的二氧化硫长途输送的影响，并通过计算中国排放的二氧化硫的贡献率来验证模型的有效性。首先，推测北京、河北、山西、辽宁、黑龙江五部委是中国二氧化硫的主要来源之一，有可能对日本产生重大影响。然后，根据以下三种情况进行了一些模拟。第一种情况是与2000年2月的情况相同的环境条件，第二种情况是环境措施没有充分进展的悲观情况，第三种情况是环境措施像日本目前情况那样取得进展的乐观情况。根据每种情景的模拟结果，对日本关东地区部分地区二氧化硫12小时释放后的沉降量进行了考察。例如，在释放后的10天内，场景1的平均沉降量为21.37μg/m，场景2的平均沉降量为24.23μg/m。因此，方案2中的沉淀量与方案1中的沉降量的比率为1.134(=24.23/21.37)。同样，方案3中的沉淀量与方案1中的沉淀量之比估计为0.344。根据一些地方的测算结果，如果到2010年中国的环保措施进展不够充分，那么输送到日本的二氧化硫沉降量将增加到目前环境条件下的1.1-1.2倍。相反，当环境措施取得进展时，沉积量将减少到日本的0.3-0.4倍。此外，本研究还将二氧化硫空气浓度的模拟结果与其观测数据进行了对比。情景1中最低层的平均空气浓度估计在新泻市约为0.217 ppb。根据国家科技政策研究院的报告，2000年中国五部委的二氧化硫排放量估计为392.3万吨，中国全境的二氧化硫排放量为2208.6万吨。由于后者是前者的5.63倍，因此从中国全境向新泻市输送的二氧化硫浓度可近似为1.222 ppb(=0.217×5.63)。另一方面，根据国家环境研究所的报告《环境数值数据库》，同期新泻市观测到的二氧化硫浓度平均约为2 ppb。因此，从中国全境向新泻市输送的二氧化硫浓度的贡献率估计为0.611(=1.222/2.0%)，即约60%，与以往研究的估计值相比，这似乎是一个有效的估计。
The current study investigated a series of transport processes of sulfur dioxide, which is an acid material transported from China to Japan in the winter season, through material transport simulations using the advection and dispersion model HYSPLIT4 (Hybrid Single-Particle Lagrangian Integrated Trajectory version 4), which has been developed by Draxler et al. This model assumes materials can be represented by particles or puffs (or both) and calculates their advection, dispersion and deposition processes based on the Lagrangian method. In the current study, experimental simulations based on three scenarios were performed to understand the influence of long-distance transport of the sulfur dioxide released from mainland China in the winter season, and in addition, the validity of the model was examined through the calculation of the contribution ratio of sulfur dioxide from China. Firstly, it was supposed that the five ministries of Beijing, Hebei, Shanxi, Liaoning and Heilungjiang are one of main sources in China of the sulfur dioxide with the potential for a great influence on Japan. Some simulations were then conducted based on the following three scenarios. The first one is a scenario with the same environmental condition as the situation in February 2000, the second is a pessimistic scenario where environmental measures do not progress sufficiently and the third is an optimistic scenario where environmental measures progress like the current situation in Japan. Based on the simulation results in each scenario, the deposition amount of the sulfur dioxide after its 12-hour release was examined at some places of the Kanto region in Japan. The deposition amount in the Tsukuba city, for example, was 21.37 μg/m in Scenario 1 and 24.23 μg/m in Scenario 2 on the average in 10 days after the release. Thus, the ratio of the deposition amount in Scenario 2 to that in Scenario 1 was 1.134 (=24.23/21.37). Likewise, the ratio of the deposition amount in Scenario 3 to Scenario 1 was estimated to be 0.344. According to the results at some places, if environmental measures will not sufficiently progress by 2010 in China, the deposition amount of the sulfur dioxide transported to Japan will increase to 1.1-1.2 times as much compared to the same environmental condition as the current situation. To the contrary, the deposition amount will decrease to 0.3-0.4 times as much when environmental measures will progress as they do in Japan. In addition, the current study compared the simulation results of the air concentration of sulfur dioxide with its observation data. The mean air concentration in the lowest layer in Scenario 1 was estimated to be about 0.217 ppb in the Niigata city. According to the report of the National Institute of Science and Technology Policy, the sulfur dioxide emitted from the five ministries of China in 2000 is estimated to be 3,923,000 ton, and that emitted from the whole land of China is 22,086,000 ton. Since the latter is about 5.63 times as much as the former, the concentration of the sulfur dioxide transported from the whole land of China to the Niigata city can be approximated to be 1.222 ppb (=0.217x5.63). On the other hand, according to the report “Environmental numerical value data base“ of the National Institute for Environmental Studies, the sulfur dioxide concentration observed in the Niigata city in the same period is about 2 ppb on average. Thus, the contribution ratio of the sulfur dioxide concentration transported from the whole land of China to the Niigata city is estimated to be 0.611 (=1.222/2.0), namely about 60%, which seems a valid estimate by comparison to estimates in past studies.