These questions are not clear,naive and SIMPLISTIC , but I will try )
Q1: what law it is > they are called enviromental laws
Q2: how this law will take effects > As soon as it is enacted and carried out by enviromental officers.
Q3: whether the environment has been improved by this law > How would I know ! Ask those Dept invloved that have all the information - before and after a new law is passed . )
Q4: explain what the government should do to improve the environment > That is why they come up with various enviromental laws to protect the enviroment .