runoff contains chemicals / fertilizer / pollutants / pesticides from cropland
runoff is not surplus. cars is major_cause_of_pollution. acid_rain is not form_of_pollution. acid_rain is not serious_form_of_pollution. noise_pollution is pollution. acid_rain is form_of_pollution. fertilizers_agricultural_chemicals is not chemicals. acid_rain is serious_form_of_pollution. runoff is surplus. fertilizers_agricultural_chemicals is chemicals.