Chapter 1 W01_0222

如果霧霧的，且濕度不高，則肯定是空氣污染物

台灣的pm2.5 約20%來自境外，境内還是大部分。

Ar氬氣 做實驗常用，惰性稀有氣體

1.1 上課

Stratosphere, absorption and scattering of solar energy occur; the lower portion contains the stratospheric ozone layer, which absorbs harmful ultraviolet (UV) solar radiation. Long-term accumulation of chlorofluorocarbons (CFCs) and other gases released at the earth’s surface or by high-altitude aircraft affect this layer. 平流层，太阳能的吸收和散射发生；下部含有平流层臭氧层，吸收有害的紫外线太阳辐射。长期积累的氯氟烃和地球表面或高空飞机释放的其他气体影响这一层。

Troposphere, which we live and is the primary focus of this course; however, stratospheric ozone formation and destruction in some detail will be also discussed. 我们生活的对流层是本课程的主要重点；不过，还将详细讨论平流层臭氧的形成和破坏问题。

• Troposphere 對流層

顆粒物、有機氣膠，可能會成核、成雨、成冰

污染物可以溯源，北極檢測到的污染物，溯源到中國

會吸收陽光輻射的污染顆粒物，附著在北極的冰，會吸收太陽熱能，加速冰層溶解

• Stratosphere 平流層（以上就是大氣系的專業）

Tropospheric Composition - “Unpolluted” air in the troposphere means the composition of the air without human influence.- Other constituents, water vapor and other vapors (e.g. organic liquids), as well as liquid and solid phase constituents (aerosols or particulate matter (PM) held in suspension). Air pollution terminology generally breaks matter down into two phases, particulate and gas. - Particulates and aerosols are generally synonymous terms in air pollution literature, i.e. liquid and solid phase. They are distinguished from gases and vapors.

• Thermodynamic systems are classified into two major types: closed and open. A closed system does not allow material to enter or leave the system (refer to “control mass”); a open system allows material to enter and leave the systems (known as “control volume”).
• Another thermodynamic concept is that of the “property”. An intensive property is independent of the system’s mass (such as pressure and temperature). An extensive property is proportional to the mass of the system (such as density or volume). Dividing the value of an extensive property by the system’s mass gives a “specific property”, such as specific heat, specific volume, or specific gravity.

The thermodynamic term for the description of the change of a system from one stage (e.g. equilibrium) to another is known as a “process”. 描述系统从一个阶段（例如平衡）到另一个阶段的变化的热力学术语被称为”过程”。

Processes may be reversible or irreversible; they may be adiabatic (no gain or loss of heat, so all energy transfers occur through work interactions) or non-adiabatic (will be introduced in the following chapters). 过程可能是可逆的或不可逆的；它们可能是绝热的（没有热量的得失，因此所有能量传递都是通过工作相互作用发生的）或非绝热的（将在以下章节中介绍）。

Other processes include isometric (constant volume), isothermal (constant temperature), isobaric (constant pressure), isentropic (constant entropy), and isenthalpic (constant enthalpy). 其他的过程包括等距（恒定体积）、等温（恒温）、等压（恒压）、等熵（恒熵）、等高温（恒移差）。

Phases partitioning means the substance will exist in one or more physical phases. An important partitioning coefficient for air pollution is Henry’s Law, which states that the partial pressure of a compound can be related to its equilibrium concentration in a dilute aqueous solution through a constant of proportionality. 阶段划分意味着物质将存在于一个或多个物理阶段。空气污染的一个重要分配系数是亨利定律，该定律指出，化合物的分压可以通过比例常数与其在稀水溶液中的平衡浓度有关。

\(e^p = e^{kc}\)

e ≈2.71828; p:溶液上的氣體分壓(partial pressure) C: 溶液體積莫耳濃度; k: Henry constant (因溶劑和溫度的不同而感變)

A varying number of molecules will find their way into the air, even though most of the molecules remain in the water, i.e. dissolved in water. Even a small amount of partitioning can account for large amounts of vapor phase compounds in the atmosphere. 不同数量的分子会找到进入空气的途径，即使大部分分子留在水中，即溶解在水中。即使是少量的分隔也可以解释大气中大量的气相化合物。

The predominant vapor in the air is, not surprisingly, water vapor. 空气中的主要蒸气是水蒸气，这并不奇怪。

In the atmosphere, above their temperature of condensation, vapor molecules act just like permanent gas molecules in the air; below its condensation temperature, if the air is saturated, water changes from vapor to liquid. 在大气中，在其冷凝温度之上，蒸气分子的作用就像空气中的永久性气体分子；低于其冷凝温度，如果空气饱和，水从蒸气变为液体。

This phenomenon gives rise to fog or mist in the air and condensed liquid water on cool surfaces exposed to air. 这种现象在空气中产生雾或雾，在暴露于空气的凉爽表面上凝结液态水。

Gaseous composition in Tables 1.1 is expressed as parts per million by volume - ppm (vol.) or ppmV. 單位很重要！！！

濃度轉換 > To convert from units of ppm (vol.) to µg m-3 , it is assumed that the ideal gas law is accurate under ambient conditions. A generalized formula for the conversion at 25 °C and 760 mmHg is:

\[ \begin{aligned} \mathrm{1ppm(vol.) pollutant} &=\mathrm{\frac{1l pollutant}{10^6 1 air}}\\ &=\mathrm{\frac{(1l/22.4)\times MW \times 10^6 \mu g }{}} \end{aligned}\]

Where MW equals molecular weight (g mol-1). For convenience, conversion units for common pollutants are shown in Table 1.3 (next slide)

More than 90% of the degradation of methane is by oxidation, mainly by reactions with the hydroxyl radical in the stratosphere which accounts for more than 90% of methane loss. The equilibria and fate of CO2, CH4, and other carbon compounds are discussed in detail in the following chapters.

Essential compounds include micronutrients needed by plant life and other organisms in the ecosystems. However, even essential substances can become pollutants in the wrong concentrations. Thus, expression of chemical concentration is crucial to understanding atmospheric science generally and the fundamentals of air pollution specifically.