FAQs2019-11-26T08:50:15+00:00

FAQs

What is a composite sample?2019-11-19T10:14:09+00:00

At a single site, collect sediment from as many different sediment deposits as possible, then combine them to give an overall sample for the site. This will then be representative of this site, as a whole.

Why are we not collecting water samples?2019-11-19T10:13:43+00:00

Pesticides can sit in the sediment for a long time before being broken down; in water they decompose more quickly, therefore sediments provide a better fingerprint. And it’s easier to transport!

Why do we need to mix the sediment samples in a bucket before filling the 2 jars and the plastic tube?2019-11-19T10:13:13+00:00

So that the same mix of sample goes into each of the jars going to three different labs.

Why are there 2 jars a plastic tube (falcon tube) in my kit?2019-11-19T10:12:26+00:00

These three containers, all filled with sediment from one site, go to 3 separate labs for analysis, being:

  • the pesticide screen
  • carbon analysis, and
  • particle size analysis
If I have fast moving sandy streams- should I sieve my samples?2019-11-19T10:11:44+00:00

Please No; as then results won’t be comparable to all other samples collected in the program.

What size fraction is most appropriate for collection- how fine is fine?2019-11-19T10:11:08+00:00

You are not required to work out the size fraction of sediments you collect. For those wanting a figure it’s less than 4 microns.

We will be taking photos of what mud/ fine sediment look like compared to sandier sediment, to help in identifying a the most appropriate sediment to sample in the field.

If I have trouble getting fine sediments – the plume cloud disappears before I get it into the bucket, what can I do?2019-11-19T10:10:19+00:00

Soils are a good substitute for sediment, this works equally well if you have a dry river bed.

If anyone is expecting a dry river bed, please let us know, as we will supply a dust pan and brush to broom the top fraction of soil from the river bed or even paddock. Sample hygiene- washing the dustpan and brush between samples will still be required. 

 

If pesticides are not detected at a site, is it worth resampling there?2019-11-19T10:08:02+00:00

Yes, as presence/ absence and concentrations change over time- e.g. some pesticide applications occur seasonally

Can I sample in my local estuary?2019-11-19T10:07:36+00:00

Yes, so long as there is mud or fine sediment to sample

What if my site is dry?2019-11-19T10:07:04+00:00

You can still collect a soil sample from the dry riverbeds.  If anyone is expecting a dry river bed, please let us know, as we will supply a dust pan and brush to broom the top fraction of soil from the river bed sample. Sample hygiene- washing the dustpan and brush between samples will still be required, so you’ll need to take some extra water with you to the site. 

If I want to sample a few times on the same waterway, how many km apart should sites be?2019-11-19T10:06:34+00:00

There is no minimum distance between samples, however we are looking for changes in landuse which may mean a change in the pesticides present. Sites chosen on the same river or creek could be above and below a township, above and below farming etc.

Do I need to nominate a reference site?2019-11-19T10:05:49+00:00

No reference sites are required for this project as the aim is to screen for pesticides

Why do you prefer sediment samples from small creeks and rivers rather than big rivers?2019-11-19T10:05:16+00:00

Small creeks are often easier and safer to access for fine sediment and the concentrations found are usually less dilute.

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