meth_1.15 Water Sampling from Acidic Saline Lakes

Contributor(s): Elizabeth Watkin (E.Watkin@curtin.edu.au); Katelyn Boase (katelyn.boase@postgrad.curtin.edu.au)

Citation:

AM Project ID: AM0019

Based on the Coastal Seawater Sampling methodology (1.7) with the following modifications:

  1. Skim water from shallow pools, taking care not to touch sediment, swirl in the bucket, and dump out to rinse. In the same manner, collect ~ half a bucket of water for sampling.
  2. Suck 50 mL of seawater from bucket into a syringe. Wash syringe a few times. Attach a 0.45 µm syringe filter and push a few millilitres into three 50 mL Falcon tubes. Wash tubes with filtrate three times. Then fill tubes with 40 mL of filtrate, close tube and keep on ice. Samples are then frozen once returned to the laboratory (-20 °C). These three tubes are for nutrient analysis and please label them according to the instruction given in the spreadsheet “sampling_schedule”.
  3. Use the 50 mL syringe from step 2 to 5 times filter 50 mL of seawater (from the bucket of step 1) through a syringe filter holder containing a 25 mm Whatman GF/F filter. If the filter does not show colour, then filter more water through it. At the end, press air through it to dry filter. Place GF/F filter into pre-labelled cryovial and snap-freeze in liquid N on site. Repeat three times. These filters will be used for chlorophyll analysis.
  4. Pipette 1 mL of water (from the bucket of step 1) into a pre-labelled cryovial with paraformaldehyde (1% v/v final concentration). Invert tube a few times and then snap-freeze in liquid N on site. Repeat three times. Use gloves and dispose of pipette tip into a sealed container for safe disposal back in the lab. These samples will be used for cell counts.
  5. For microbe sampling, we use PES filter towers (0.2 µm and 0.1 µm Nalgene™ Rapid-Flow™ Sterile Disposable Filter Units with PES membrane #catalogue numbers TBC) with a hand vacuum pump and 500 mL – 1L capacity and filter until the salt blocks the filter. Aim to filter 1 L, but stop and record volume filtered if less than this.
  6. When the water has been filtered continue to run the pump for 1-2min to remove all of the liquid. If the filter gets blocked before, then note the approximate volume filtered, and try to pump air through the filter for 1-2 min to remove remaining liquid.
  7. Filters are placed in sterile Whirlpak bags and labelled appropriately.
  8. Freeze immediately at -80 °C.