Which will have a greater affect on the potential energy of someone. doubling the height or doubling the mass?

Both of them should have the same effect on the potential energy. To calculate potential energy, you use the formula mass*acceleration of gravity*height (m*g*h). So since each value carries the same weight, doubling the mass would have the same effect as doubling the height. 

Nps pollution is caused by rainfall or snowmelt moving over and through the ground. nonpoint source pollution can include: excess fertilizers, herbicides and insecticides from agricultural lands and residential areas. oil, grease and toxic chemicals from urban runoff and energy production

The answer is frictional force