Thanks for your reply. We are collecting samples for both qPCR with targeted probes and 454 sequencing. The sites are in the high Arctic and remote. Therefore, our working plan is to freeze the cores and section them when we return to our home labs. We could exact DNA in the field lab, but we have found QA/QC is better when we perform the sectioning back at our home labs. The problem we have had i the past is cutting through soils with large stones and boulders, and getting into the top of the permafrost layer.

Thanks. We are coring in the late summer, therefore the temperatures tend to be slightly above freezing. Access to some sites require long walking treks across tundra. Therefore, things need to be as compact and light as possible.