Acids and bases affect our environment significantly by altering it. These alterations may be beneficial in some cases, while in others, maybe really harmful.
Acids and bases occur naturally in our environment, most commonly in our soil and water. Their presence changes the pH of the environment. Acids causes the pH to fall below 7, while bases increase it beyond 7, the change depending upon the amount of acids/bases, etc. Depending on the presence of acids and bases, soils may be acidic or basic or neutral and will thus support organisms (most commonly, the soil bacteria) that prefer those environments. This also affects the type of plants that can grow in that environment. Similarly, water in natural streams (rivers, etc.) can also have acidic or basic or neutral pH and will, correspondingly, support specific life forms.
Acids and bases can also be released into the environment by human activities. Acid rain is a direct effect of human activities and causes dissolution of rocks and minerals.
Hope this helps.