what are the enviromental problems related to the use of fertilizers and pesticides and how we can avoid them?

Answer 1

Problem with pesticides is that they don't always kill just the target organism. Insecticides kill beneficial insects like bees, and aquatic insects (which wills tarve fish, if no longer there), lady bugs, preying mantises, and so the pests bounce back, while the control insects don't so quickly. Herbicides often kill even the natives and leave room for the invasives to come back, then you kill them with herbicide again, and you have a viscious circle. Ugly.

Fertilizers can cause an overgrowth of algae which can cause oxygen levels to plummet in the waterways, killing fish and anything else that that uses oxygen in there.

We can limit our use of fertilizers and pesticides to need only. Don't use them just because we can. Use only if we see a problem, use according to the label (although for urban areas, that isn't necessarily true). Don't overuse, more is NOT better.... We can avoid allowing water from the sites to move into the waterways, like no overwatering of the lawn.

Anywho, I hope that gets you started on what I am assuming is your homework.