国际海运对氮氧化物及对流层臭氧的影响-英国dissertation

1.  Impacts of International Shipping - NOx and Tropospheric Ozone
国际海运对氮氧化物及对流层臭氧的影响

1.1. Introduction
介绍

Although NOx and ozone are local and regional air pollutants that also produce global climate change, the local and regional air-pollution problem is quite different from the global climate-change problem.  The first part of this chapter describes the differences between the air-quality concerns and the global climate concerns surrounding NOx and ozone.  The remaining sections focus entirely on the global effects.
虽然氮氧化物和臭氧是当地和区域空气污染物，也会产生全球气候变化，全球气候变化问题的地方和区域空气污染问题是完全不同的。

1.2. Local and Regional Effects of Ozone
臭氧对局部和区域的影响

Unlike most traditional air pollutants, ozone (O3) is not emitted directly into the atmosphere.
Instead, it is formed in the atmosphere through a series of complex photochemical reactions.
Thus, it is referred to as a secondary pollutant, as opposed to a primary pollutant that is directly emitted.  In the troposphere, ozone is formed through reactions of volatile organic carbon (VOCs) and NOX in the presence of sunlight. However, this simple description belies the complex chemistry that is actually involved.  Ozone is only formed via the photolysis of nitrogen dioxide (NO2). Instead of actually playing a molecular role in the chemical reaction that directly forms ozone, the presence of VOCs affect the efficiency with which NOX forms ozone.
与大多数传统的空气污染物相比，臭氧（O3）没有直接排放到大气中。相反，它是通过一系列复杂的光化学反应，在大气中形成。因此，它被称为作为二次污染物，而不是直接排放到主污染物。

VOCs affect the formation of ozone through a chain of oxidation reactions. These chain reactions consume VOCs while recycling NO to NO2, which is then available to produce more ozone. In many areas, there may be hundreds of different species of VOCs as a result of pollution or naturally occurring processes (e.g., from forests   http://ukthesis.org/ygsslwdx/  ).  Each of these species follows a different reaction pathway at a different rate and produces different products. VOC species that have been observed in ambient air can be divided roughly into three equally sized groups: For one third, including the simplest organic compounds, the reaction pathways, rates, and products are well characterised. For the second third, the reaction pathways and products are known, but the rates and product yields are not. For the last third, including most aromatic compounds, scientists can only make educated guesses as to the reaction pathways, rates, and products, although research continues to make progress in this area.#p#分页标题#e#
对于三分之一，包括简单的有机化合物，反应途径，价格，和产品是很好的特点。对于第三分之二部分，反应途径和产品是已知的，但比率和产品收率都没有。最后的三分之一，其中大多数是芳香族化合物，科学家们只能猜测反应途径，比率和产品，在这方面研究会继续取得进展。

The formation of ozone via the photolysis of NO2 competes with the formation of nitric acid, peroxyacetylnitrate (PAN), and other organic nitrates, which eventually remove nitrogen from the ozone-formation cycle.  Ozone is also eventually removed from the troposphere by photolysis, reaction with NO or VOCs, or surface deposition. Thus, the formation of ozone is dependent on the fate of NOX, which is in turn dependent on the quantity and composition of the VOCs present.
因此，臭氧的形成取决于氮氧化物的命运，反过来又依赖于在场的挥发性有机化合物的数量和组成部分。

The relationship between ozone formation and the initial concentrations of NOX and VOCs is highly nonlinear and varies during the year. An ozone isopleth diagram, such as Figure 4.1, best describes this relationship.  Initial concentrations of NOX are plotted along the vertical axis and initial concentrations of VOCs are plotted along the horizontal axis.  The series of curves show different maximum ozone concentrations associated with each combination of NOX and VOC.
该系列曲线显示不同的最大臭氧浓度的氮氧化物和挥发性每个有机化合物组合。

For example, at Point A in Figure 4.1, ozone formation is VOC-sensitive; a change in VOC will significantly change the ozone level.  However, the opposite is true at Point B, which is NOx -sensitive. It is important to realize that these diagrams differ for each location in the atmosphere and vary with meteorological conditions and changes in the distribution and composition of emissions.  Thus, the control recommendations that are inferred from such a diagram are only valid for the conditions under which the diagram was constructed.
因此，从这样一个图推断控制，建议仅适用于在何种条件下构造图表。

Figure 4.2 shows that, in general, ozone formation in marine regions is more sensitive to the presence of NOx than of VOCs (NOx-sensitive).  The implication that ocean regions are not
VOC-sensitive is illustrated by the fact that increasing VOCs by a factor of ten while holding NOx  relatively constant (moving from the “marine box” to the “remote tropical forest” box) does not change the typical concentrations of ozone.  However, urban regions with the same VOCs as the remote tropical forest regions but increased NOx concentrations show significantly higher concentrations of tropospheric ozone (see Figure 4.2).  It appears that the naturally-occurring VOC concentrations over ocean regions may be sufficient to react with additional NOx concentrations in shipping lanes to produce higher ozone concentrations in those regions.  As discussed in 4.2.2 and in Appendix A2, this appears to be confirmed by model predictions of nitrogen and tropospheric ozone concentrations attributable to international shipping.#p#分页标题#e#
与额外的NOx浓度相比，天然存在的挥发性有机化合物的浓度超过海洋区域可能是足够的反应。在出货通道，这些区域产生较高的臭氧浓度。正如在4.2.2和附录A2，这似乎证实模型预测是由于国际航运氮和对流层臭氧浓度引起的。

While stratospheric ozone protects the surface of the earth from harmful ultraviolet radiation, tropospheric ozone is a powerful oxidant that damages human lung tissue, vegetation, and other materials.
Short-term exposures (1 hr to 8 hr) to high concentrations can cause a range of acute adverse human health effects from irritation and shortness of breath to decreased immune functions and increased inflammation and permeability of lung tissue.  Young children, the elderly, and individuals with preexisting respiratory disease are at particular risk of serious acute adverse effects from ozone exposure.  The chronic human health effects of ozone exposure are less well known, but there is the possibility of irreversible morphological changes of the lung, genotoxicity, and carcinogenicity.
年幼的孩子，老人，与原有的呼吸系统疾病的个人，有臭氧暴露严重的急性不良影响的特定风险。臭氧暴露的慢性人体健康的影响，是众所周知的，但有肺癌，遗传毒性，致癌性的不可逆的形态学变化的可能性。

Figure 4.1. An idealised example of the relationship between ozone and its precursors [Keating and Farrell,1999]
Figure 4.2.  Ranges of VOC, NOx and ozone concentrations in the atmospheric boundary layer for four regions of the atmosphere [National Research Council, 1991], with placeholder box for ozone in shipping lanes produced from NOx from ships.

The adverse effects of ozone exposure on vegetation include leaf yellowing, premature senescence, reduced growth, and increased susceptibility to pests and other risks.  These effects occur with agricultural crops and other vegetation.  While the magnitude of the concentration is often more important than the duration of exposure for human health effects, both are important with respect to impacts on plants.  A variety of metrics has been proposed for measuring ozone exposures to plants. Most involve counting the number of hours that exceed a threshold concentration during summer daylight (concentration hours).  Exposure to ozone also leads to the oxidation and deterioration of many important materials including paint, textiles, rubber, and plastics.
臭氧对植被的不利影响，包括叶片黄化，早衰，降低了增长，害虫及增加其他风险的敏感性。这些影响发生在农作物和其他植物。

These concerns were the primary motivation for domestic and international (e.g., transboundary) policy attention on NOx and ozone.  In fact, the realisation that NOx from ships contributed significantly to air quality problems in regions with heavy ship traffic motivated action at IMO that resulted in MEPC Annex VI.#p#分页标题#e#
这些担忧是氮氧化物和臭氧（如，跨界）国内和国际的政策关注的主要动机。事实上，实现NOx的船舶贡献显着的地区的空气质量问题与沉重的船舶交通动机的行动，在国际海事组织在MEPC附件VI。