The Tellus geochemistry field programme requires the careful collection of samples from streams.
Routinely, samples of stream water, stream sediment, heavy mineral panned concentrate
and vegetation are collected from drainage channel sites in rural areas.
Care should be taken in selecting a suitable site,
which is accessible and safe to work in.
In the stream bed and the water that flows through it, we will find traces of all the
material that has been washed down from the surrounding catchment into the drainage channel.
Collecting samples from a stream is essentially taking a composite subsample from the
entire catchment that is upstream of the site.
At the chosen sample collection site, note the exact location
using your handheld GPS unit.
Cross check the location on your 1:50,000-scale field map.
Both field samplers should be involved in this process to ensure accuracy.
When you are satisfied with the location, begin unloading your equipment.
This should be done close to or in the stream and on a stable surface.
The sampling equipment to be used is generally non-metallic; this is because we are trying
to establish the very low concentrations of metals and other elements, and to avoid introducing
them from the sampling process.
Sampling teams will use a ‘site bag’ that contains one of each of the containers that
you will need to collect samples.
Inside the site bag is a smaller polybag containing two bottles used to collect filtered water.
Before beginning any sampling, all containers need to be labelled at the same time,
by the same sampler.
It is critical to label the containers before sampling begins, not afterwards.
Label all containers with the six figure site number.
On all bottles, numbers must be written legibly along one side,
always starting from the cap end.
On the larger bottle from the inner polybag, write ‘F/A’ to denote filtered and acidified.
This acidification will be carried out upon return to the field base at the end of a day.
On the smaller bottle, the number may be written on one line or be divided across two lines,
always with two digits above and four below.
Write ‘F/UA’ on this bottle to denote filtered and un-acidified.
Once these bottles are labelled, return them to the smaller polybag and tie up the bag
with a loose knot.
There are two other bottles in your site bag, these are recycled and reused
throughout the field campaign.
These are both used to collect unfiltered stream water that will be tested
at the field base.
Label each bottle with the site number only, always starting from the cap end.
The site bag also contains three brown Kraft® paper bags— two small and one large.
The six digit site number should be clearly written approximately one third to half way
down on each bag, this will allow the label to be visible when the bag is sealed.
Write the letter ‘V’ on the first small bag to denote vegetation sample.
Also write your initials and those of your field partner on all bags.
On the other small bag, write the letter ‘P’ to denote panned concentrate, along with your
own and your partner’s initials.
On the larger bag, write the letter ‘C’ to denote stream sediment,
and once again initial.
Once labelled, return all brown bags to the site bag.
You are now ready to start sampling.