The line graph describes the amount of UK acid rain emissions produced by four sectors from 1990 to 2007
.... Good start
.... you use "an" when the following word starts with a vowel
To specificMore specifically, , after a dramatic fall for the first five years, the amount of acid rain emissions released by electricity,gas and water supply underwent a slight increase in 1999, ending the period with a decrease to 0,5 million tones.
... You can also say "in detail"
In brief, while transport and communication sectors increased (what?) over years, the opposite true of other sectors.
... this line is not well presented. It is not clear too :( ... Also, you need to state the overall trend here;In brief, the contribution of all sectors to acid rain emissions have dropped over the years.
I think this website provide a good framework for tackle this task' - hope this is helpful :)