[Air-L] Monitoring tags on Tumblr, Instagram, Pinterest etc

Hi all Does anyone know of an easy way of keeping track of tags over time in Tumblr, Pinterest or Instagram. I'm especially interested in numbers of tags over time and particular spikes in their popularity, and, if possible, how manh unique users are associated with them and other tags often used in conjunction. Also, is there any way you know of of being able to see how often things have been crossposted across different social media platforms (ibc flickr, twitter, facebook etc)? Ruth