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Groundwater and Spring Sampling Procedure

Tasks:

Environmental samples may support the biotic collections in several ways:

  • Collect groundwater samples from either mini-wells or springs, and obtain field parameters
  • Locate site with GPS coordinates

Procedure:

Locate site with GPS coordinates

  • Select site for sampling -- not all lakes will be able to be sampled, because of lack of time. Try to select sites from a variety of salinities. Are the source groundwaters really different, or are the lake salinity differences really due to different evaporative concentrations from differing residence times? Note also that for lake with a surface-water inlet, assume that this inlet dominates any gw inflow, and just ignore possible gw inflows (unless you've got time to check this assumption and actually sample this influent groundwater).
  • Locate upgradient side of lake with mini-piezometer. Consider local topography and inferred direction of regional groundwater flow (toward nearest discharge point = stream or river). Note delta-phi / depth of screen = head gradient, if possible -- but qualitative measure is of most value. Seek out obvious spring seeps into lake, and avoid mini-p measurements entirely.
  • To avoid sampling lake-influenced water -- especially from very saline lakes -- consider moving 5-10 m upgradient from the lake shore. Dig or auger hole, perhaps, and/or drive second mini-well to water table for sampling. Surge/purge well (but don't purge with lake water, for fear of contamination).
  • Maybe -- bring along lock level and field rod of sort, to check elevation of water in hole vs. lake level (and calculate horizontal gradient).
  • Locate site with GPS coordinates (while mini-p is equilibrating, perhaps...)
  • Pump/flush well with peristoltic or vacuum pump
  • Obtain field parameters with YSI sonde and flow-through cell
  • Collect in-situ samples for alkalinity, isotopes
  • Collect field sample for later processing
  • Label each sample, possibly with stick-on labels partially written out with lake ID and date

Springs:

  • Locate site with GPS coordinates
  • Obtain field parameters with YSI sonde, in spring pool (or pump through flow-through cell, if necessary)
  • Collect in-situ samples for alkalinity, isotopes (perhaps with peristoltic pump, if necessary)
  • Collect field sample for later processing (ditto)
  • Label each sample, possibly with stick-on labels partially written out with lake ID and date

General Notes:
Despite the above plans, groundwater sampling was limited to spring and existing wells (which were few). There wasn’t enough time to characterized lake/groundwater interactions at selected sites, nor did we have the room to bring along the extra min--piezometer equipment that would’ve been necessary. This work will have to wait until a few sites are selected for more focused study.

Equipment and supplies:

  • Hip boots, or stocking-foot hip waders, or "wading pants"
  • Tupperware bins for organizing/storing equipment?
  • GPS unit
  • Mini-piezometer and manometer board. Accessory tubing, connectors, clamps, etc.
  • Sampling mini-well, pounder, surger, purging pump?
  • Auger or pack shovel? Hand trowel? For digging to water table...
  • Lock level (hand level)
  • Collapsible level rod, plus attachment to "stick" it into hole and mark groundwater level vs. lake level (stand at lake shore, and shoot rod marking gw level in hole...e.g.)
  • YSI sonde with T, SC, DO, and pH probes, with flow-through cell
  • Peristoltic pump (hand-operated) and/or vacuum bottle
  • Strainer? Mini-well screen? for pump intake tubing... at springs, in holes?
  • Field sampling bottles -- probably 1 L, but maybe only 500 mL. No smaller than that, I'd say.
  • Maybe -- sample bottles for field alkalinities (with cone-lids), in addition.
  • Isotope bottles
  • Label tape and sharpies
  • Stick-on labels