Fact 1: Landfills have a negative impact on the environment.

Fact 2: Landfill leachates and groundwater contamination.

Given the two facts above, answer the question "what have a negative impact on the environment" with the following options: 
- harmful substances
 - groundwater contamination
 - harvesting
 - fish
 - major threat to health
 - Sulfur dioxide
 - storms
 - Greenhouse gases


 

  groundwater contamination       