Watch for changes to a section of a Wikipedia page

If you click the View History link for an article you can see the list of changes made to the article, on what date, and by whom. A short summary of the change description is also displayed. You can then click the Compare selected version button to compare text.

Unfortunately, I'm not aware of a Blame feature that lets you directly see who made the changes to a particular line or sentence or paragraph.

EDIT: You may want to check out Greg Hewill's site, he (apparently) is working on just such a blame feature.

First, let me say that I don't think doing this is a good idea. Category description pages on Wikipedia shouldn't contain article text, that's not what they're for. If you want to do this, make sure there is a consensus to do it. For some more information, see Creating category pages.

If you're sure you want to do this, I think the only way (ignoring custom or some existing extension) is to use template transclusion. This can be done two ways:

If you know that you'll always want only this specific section, you can enclose it in <onlyinclude> tag. Then you can transclude the article to the category page (e.g. {{:Pollution in India}}) and only this section will show up.

But if you want to transclude different sections of the same article to different categories, that won't work (unless you also added some {{#if}}s to the article, which I don't think is a good idea). What you can do then is to split the article into multiple parts, each within its own template. So, the text of the section Water pollution might be in Template:Pollution in India/Water. Then you can transclude that template to both the article and the category (using {{Pollution in India/Water}}).