Check out the following: http://www.sqlservercentral.com/Forums/Topic1340744-391-1.aspx

If you order by Virtual_memory_committed_kb, you should see MEMORYCLERK_SQLBUFFERPOOL as the largest consumer of memory.

select * FROM sys.dm_os_memory_clerks

order by Virtual_memory_committed_kb desc

I'm still trying to find a definitive reference that adequately defines sys.dm_os_memory_clerks and what all of the columns mean.