Problem 1
Atmospheric pollutants are sometimes classified into two categories: (a) primary pollutants-those that are emitted directly from the source; (b) secondary pollutants-those that are produced by reactions in the open atmosphere. Which category(s) would each of the following fall into? Carbon monoxide, carbon dioxide, sulfur dioxide, nitric oxide, nitrogen dioxide, ozone, PAH compounds, formaldehyde.
Problem 3
In the uranium-238 decay series, radium-226 is an immediate radioactive parent of radon-222. Consider its position in the periodic table and indicate its usual oxidation state, its probable mobility in water, and factors affecting its solubility in soil/water systems.
Problem 4
As an experiment, gas cooking units were activated until high levels of carbon monoxide and \(\mathrm{NO}_{x}\) compounds were measured in a house and then the gas burners were turned off. The carbon monoxide levels returned to background values in \(1.6 \mathrm{~h}\), but the \(\mathrm{NO}_{x}\) levels only required \(0.7 \mathrm{~h}\) before they had reached the 'normal' concentration. Suggest an explanation.
Problem 5
\(\mathbf{5}\) In Chinese village homes, heating is often by an open wood or coal fire. Where outdoor \(\mathrm{PAH}\) concentration is \(0.60 \mathrm{ng} \mathrm{m}^{-3}\), the rate of emission of \(\mathrm{PAH}\) from indoor combustion is \(3.5 \mathrm{ng} \mathrm{m}^{-3} \mathrm{~h}^{-1}\) and the air exchange rate is \(20 \mathrm{~min}^{-1}\), estimate the indoor air concentration of PAH compounds. Assume that the only loss mechanism is by air exchange.
