Problem 2
In a particular \(3000 \mathrm{~km}^{2}\) region of southern Sweden, the annual rainfall averages \(850 \mathrm{~mm}\), its mean \(\mathrm{pH}\) is \(4.27\), and \(66 \%\) of the hydrogen ion is associated with sulfuric acid; the remaining \(34 \%\) is derived from nitric acid. Calculate whether soils of this region are subject to excessive sulfate loading if the only source of sulfate is rainfall and if the recommended maximum is set at \(20 \mathrm{~kg} \mathrm{SO}_{4}^{2-} \mathrm{ha}^{-1}\).
Problem 4
The ionic composition (in units of \(\mathrm{ng} \mathrm{m}^{-3}\) ) of an atmospheric aerosol in a tropical rain forest is \(\mathrm{SO}_{4}^{2-}, 207 ; \mathrm{NO}_{3}^{-}, 18 ; \mathrm{NH}_{4}^{+}, 385 ; \mathrm{K}^{+}, 180 ; \mathrm{Na}^{+}, 247\). The \(\mathrm{pH}\) of the aerosol is \(5.22\). Use these data to calculate the total positive and negative charge 'concentration' \(\left(\mathrm{mol} \mathrm{m}^{-3}\right)\) in the aerosol and suggest reasons which might account for any discrepancy in anionic and cationic charge.
Problem 5
The tropospheric mixing ratios of carbon monoxide are higher in the northern hemisphere than in the southern hemisphere. However, it has been observed that there has been a general global decline in carbon monoxide concentration everywhere in the \(1990 \mathrm{~s}\). Two reasons have been suggested for this -one is the eruption of Mount Pinatubo and the other is the occurrence of several relatively dry years in the tropics. Comment on these two possibilities in terms of tropospheric and stratospheric processes.
