cgrew:gzt: That would be interesting and fun project, but make sure you get the science right. The presence or otherwise of these elements will not tell you very much at all. The tests I have read elsewhere are badly performed, and on top of that misinterpret the results generated.
I have already made an enquiry with my Father who works for DOC in the Waimakariri district. His Bio guys will conduct the tests at some stage in the next few months.
There is a lot more to a science project than the testing. If you do not understand this, any data you get from the tests will be worthless as evidence.