Dear all,
I would like to collect soil water for isotopic and chemical analysis, Soil types found in my area are clay, clayey loam and gravelly clay. Can anybody suggest what is appropriate method of collecting soil water upto 1-3 meters in these soil types?
Thanking You all in advance..
Warm Regards
Rajat
Dear Rajat,
I have been using small lysimeters to collect soil water from the Irrometer company (www.irrometer.com). They call them soil solution access tubes (SSAT). The tubes come in lengths from 15 cm (6 inches) to 183 cm (72 inches) and use a vacuum to collect the water. I use a short version so can use a small syringe pump, but for longer versions, some sort of dialysis pump might be required. Also, I will say that in clay-rich soils, getting enough water to do chemical and isotopic analyses can be difficult unless the soil is pretty wet.
Sincerely,
Brannon
We made soilwater and groundwater samplers similar to those described by Dr. Anderson, using variable lengths plastic pipe, ceramic cups epoxied to pipe, and two hole stoppers in top of pipe. I think the cups that we used was for 2 inch pipe. Copper or plastic tubing goes through stopper holes, one to bottom, one to pull vacuum and apply pressure. As suggested, clay soils hold water tightly, so there could be some difficulties. One might apply vacuum and return next day or hours later to pressurize and check for sample.
I forgot to add, we drilled or dug a hole using a post hole digger to desired depth, and nested four pipes at varied levels, using sand backfill and bentonite to separate levels. Bentonite is a hazardous and messy clay material. Not sure this would work for you. You probably would be better off using a soil core sampler of appropriate size to drill hole for each sampler, avoiding the backfilling, and pushing the sampler into the cored soil to proper depth of hole, and sealing as best as you can. Sampling during wet to field capacity soil conditions probably best due to clays. Increasingly drier conditions questionable in being able to pull and maintain a strong enough vacuum to pull water out of clay. We used a bike like pump, one side pulled vacuum, other side applied pressure. Gravelly clays may produce some added difficulties. I think most of the supplies were available from Fisher Scientific catalogue.
Dear Dr. Anerson and Mr. Hansen thanks for yor valuable input, it is indeed of immense help.
Thanks and Regards
Rajat
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