How to remove a link from a pdf file

I am reading a pdf file using preview. I is a freely available research article. While marking words to look them up in the dictionary I noticed on two of the 40+ pages, the curser had changed from the "mark text"-symbol to the hand symbol as one would expect when hovering over a link. When I click on the pdf page safari opens up and lead me to the publishers website offering distantly related articles to the one I am reading at the moment. When I open the exact same pdf file in adobe acrobat 11, no such behaviour can be observed. Is there an explanation for that, more importantly can I switch the link of?

many thanks

Chris

Running mountain lion .4, Safari 6.0.5, preview 6.0.1 and Adobe acrobat 11.0.02

file in question: http://www.demographic-research.org/Volumes/Vol22/34/