$11-3.$ A $50-ft$ deep sanitary landfill in alluvial gravel has been completed for several years. The normal groundwater level is $150ft$ below the surface, or $100ft$ below the bottom of the fill. A special sampling well at the edge of the landfill shows that the atmosphere in the interstices of the soil $20ft$ above the water table contains $48$ percent $C{O}_2,28$ percent $C{H}_4,20$ percent $N_2,2$ percent $O_2,1$ percent $H_{2}S,$ and $1$ percent other gases, analyzed and calculated on a dry basis at $0C$ and $760mm$ pressure. On the basis of a long period of contact $($i$.$e$.,$ equilibrium$)$ at $10C,$ compute the concentration in $m\frac{g}{L}$ of each of these five gases to be expected in the upper layers of the groundwater under a total pressure of $1$atm at $10C.$ Assume saturation with respect to vapor pressure. $($Problem courtesy of Dr$.$ Paul H$.$ King.$)$