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Precipitation collection protocol for isotopes
Note: The goal is to collect all precipitation that falls for each month and to avoid evaporation during collection, storage, and transport
Precipitation collection protocol and supplies list for δ2H and δ18O analysis
Jason West, Texas A&M University
Note: The goal is to collect all precipitation that falls for each month and to avoid evaporation during collection, storage, and transport
Protocol
(Modified from protocols described by IAEA; http://www-naweb.iaea.org/napc/ih/documents/userupdate/sampling.pdf):
- Place plastic bottle and large funnel in a similar position as a standard rain gauge (away from overhangs, etc.). The bottle should be large enough to comfortably collect all precipitation for a given month and funnel diameter.
- Add paraffin oil (mineral oil) obtained from any pharmacy, etc. so that the precipitation will be completely covered by at least a 1 cm layer.
- Leave water aside for about a week after collecting the bottle if there has been recent precipitation to ensure complete mixing and then remove top layer of oil or collect the water using a separatory funnel into a smaller, Nalgene bottle (see below).
- Note the total volume of water in collector to compare to precipitation amounts recorded by rain gauge.
- Collect 120 mL of water into 125 mL Nalgene bottles. Ensure bottle is tightly capped and wrap Parafilm around cap to prevent cap loosening. Discard excess precipitation or collect into secondary bottle.
- The collector should be dried again before using it for the next month's precipitation.
- Always note date of collection, site, amount collected, and any other relevant observations.
Supplies
- Funnel (diameter similar to diameter of collector bottle)
- 4 L Nalgene carboys (VWR part no: 16334-184 or similar)
- Mineral oil
- Aluminum foil (wrap outside carboy if desired to reduce heat load)
- 125 mL Nalgene wide mouth bottles (VWR part no: 16129-006)
- Parafilm
- Large separatory funnel
- Pipettes
