Parts per million by volume

Because pulp bleaching agents are, for the most part, reactive oxidising agents, appropriate precautions must be taken in their handling and use. For example, it is important to ensure that the threshold limit values (TLV) (20) in Table 2 are not exceeded in the workplace air. These are airborne concentrations in either parts per million by volume under standard ambient conditions or mg per cubic meter of air. They "represent conditions under which it is beUeved that nearly all workers may be repeatedly exposed, day after day, without adverse effect" (20). TWA refers to a time-weighted average for an 8-h workday STEL is a short-term exposure limit or maximum allowable concentration to which workers can be continuously exposed for 15 minutes. 

Gaseous composition in Tables 2-1 and 2-2 is expressed as parts per million by volume—ppm (vol). (When a concentration is expressed simply... 

The large number of individual hydrocarbons in the atmosphere and the many different hydrocarbon classes make ambient air monitoring a very difficult task. The ambient atmosphere contains an ubiquitous concentration of methane (CH4) at approximately 1.6 ppm worldwide (9). The concentration of all other hydrocarbons in ambient air can range from 100 times less to 10 times greater than the methane concentration for a rural versus an urban location. The terminology of the concentration of hydrocarbon compounds is potentially confusing. Hydrocarbon concentrations are referred to by two units—parts per million by volume (ppmV) and parts per million by carbon (ppmC). Thus, 1 fx of gas in 1 liter of air is 1 ppmV, so the following is true ... 

TLVs are ealeulated using ppm (parts per million by volume), mg/ m (mg of vapor per eubie meter of air). For vapor, mg/m is eon-verted to ppm by the equation ... 

The OELs are expressed in terms of concentration, such as ppm (volume/ volume) or mg/m . For gases and vapors it is stated in terms independent of temperature and air pressure variables, in mL/m, or parts per million by volume in air, and in terms dependent on those variables in milligrams of substance per cubic meter of air at a temperature of 20 "C and a pressure of 01.3 kPa,... 

Carbon dioxide, considered a wanning gas, comprises about 0.036 percent of the atmosphere by volume. As Figure 1 shows, carbon dioxide levels have increased as a component of the atmosphere by nearly 30 percent from the late eighteenth century to the end of the twentieth century, when the level was close to 365 parts per million by volume. Prior to the period of industrialization, carbon dioxide levels were largely stable, at about 280 parts per million, though fluctuations as low as 200 parts per million or as high as 300 parts per million have been observed through analysis of air bubbles trapped in arctic ice cores. 

Fig. 1-2 Chemical data from the Vostok ice core. The graph of 5D can be taken as a proxy for temperature changes, as described in Chapter 18. CO2 and CH4 are greenhouse gases and vary in the same direction as temperature. Non-seasalt sulfate and methane sulfonic acid are both sulfur species existing in the particle phase, and are positively correlated with each other, but negatively with T. Major variations for all of these variables seem to correlate either positively or negatively with each other, indicating a coupled system. <5D, non-seasalt sulfate, and methane sulfonic acid data kindly provided by Dr Eric Saltzman. CO2 data are from Bamola et al. (1987) and Jouzel et al. (1993). CH4 data are from Chappellaz et al. (1990) and Jouzel et al. (1993). (ppmv = parts per million by volume ppbv = parts per billion by volime)...

The large value of Le results in a very strong dependence of vapor pressure on temperature. As a result, the water vapor content of the air is extremely variable, from parts per million by volume in the coldest parts of the atmosphere to several percent in the warmest and wettest... 

C05-0130. In 1990, carbon dioxide levels at the South Pole reached 351.5 parts per million by volume. (The 1958 reading was 314.6 ppm by volume.) Convert this reading to a partial pressure in atmospheres. At this level, how many CO2 molecules are there in 1.0 L of dry air at -45 °C ... 

Natural organic matter Nonpurgeable organic carbon Parts per million by volume Permeable reactive barriers Polyvinyl chloride... 

The evaluative lake environment is similar to the "unit world" described by Mackay and Paterson (2), consisting of a 1 km square area with an atmosphere 6000 m high, a water column 80 m deep (the approximate depth of Lake Michigan) containing suspended solids (5 parts per million by volume) and biota (considered to be fish) of 1 ppm by volume, and underlain by a sediment 3 cm deep. The bottom sediment contains 4% organic carbon and the value for suspended sediment was arbitrarily selected as ten times these bottom sediment values reflecting the enhanced sorption discussed by O Connor and Connally (14). 

For solids run-off it is assumed that this run-off water contains 200 parts per million by volume of solids thus the corresponding velocity term U12 is 200 x 10 6t Jn, i.e., 10 s m/h. This corresponds to the loss of soil at a rate of about 0.1 mm per year. If these solids were completely deposited in the aquatic environment (which is about l/10th the soil area), they would accumulate at about 0.1 cm per year, which is about a factor of four less than the deposition rate to sediments. The implication is that most of this deposition is of naturally generated organic carbon and from sources such as bank erosion. 

At 7 a.m., the ozone (03) content in the atmosphere over a major city is 0.002 ppmv (parts per million by volume). By noon, the measurement is 0.13 ppmv and a health alert is issued. The reason for the severity is that the region acts as a batch reactor-the air is trapped horizontally (by mountains) and vertically (by a temperature inversion at 1000 m). Assume the area of the region is 10,000 km2 and is home to 10 million people. Calculate the following ... 

Typical gaseous pollutant concentrations range from 250 to 10,000 parts per millions by volume (ppmv). Packed-bed wet scrubbers are generally limited to applications in which PM concentrations are less than 0.45 g/sm3 (0.20 gr/scf) to avoid clogging. 

The total amount of carbon monoxide in the atmosphere has been estimated at about 3.06 million short tons (2.78 million metric tons). Of this, about half (1.438 million metric tons) is produced naturally and about half (1.350 million metric tons) through anthropogenic (human-made) sources. Naturally occurring carbon monoxide is not generally regarded as an environmental problem because it is so widely spread at very low concentrations (about 0.1 ppmv [parts per million by volume]) throughout the atmosphere. 

The oxidation of chlorinated compounds produces hydrogen chloride (HCl) along with the carbon dioxide and water vapor. Some catalyst aging data suggest that HCl exposure over 10,000 parts per million by volume (ppmv) for extended periods may lead to catalyst deactivation over time. 

Destroys chlorinated VOCs at high concentrations of up to 50,000 parts per million by volume (ppmv). 

The concentration of water vapor in the atmosphere is thought to have remained steady over time, but concentrations of some other greenhouse gases are rising. From the year 1000 or earlier until about 1750, the C02 concentration in the atmosphere remained fairly stable at about 280 10 parts per million by volume (ppmv). Since then, the C02 concentration has increased by 28% to 360 ppmv. The concentration of methane, CH4, has more than doubled during this time and is now at its highest level in 160000 years. Studies of air pockets in ice cores... 

LCS0--lethal concentration, 50% mortality a measure of inhalation toxicity. It is the concentration in air of a volatile chemical compound at which half the test population of an animal species dies when exposed to the compound. It is expressed as parts per million by volume of the toxicant per million parts of air for a given exposure period. 

Crude oil production from the wellhead will always have production water flowing with it. Most of this water is what we call free water. That is, it is not dissolved into the crude oil. Soluble water in crude oil has ranged as high as 1000 parts per million by volume (ppmv), and as low as 20 ppmv. No attempt to remove soluble water is ever made in field production facilities. Rather, substantial equipment and processes are dedicated to the removal of free water. This chapter shall therefore address only free water. Refiners request, and in many cases specify, a 1% free water crude content in all pipeline crude oil received. Thus, the crude oil field production facilities must meet this 1% water requirement in treated crude oil to pipeline sales. 

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