After talking to Eric Boyd (University of Montana) at the Goldschmidt conference last year we decided it would be interesting to look at the bacterial community present at my sampling sites with the expectation that they would influence the chemical composition of the stream water. I posted off four sediment samples and now the results are back! The analysis done is called 16S rRNA sequencing: bits of RNA are sequenced and compared with a database of known bacteria to see if they match. This approach gives an idea of which bacteria are there but not whether they are active or not. Now I have to read up on microbiology in order to understand this data!