Soil water sampling
UMS offers a wide range of pore water samplers, leachate samplers and vacuum devices. For straight results it is decisive to select the suitable material, the correct type of sampler and the proper vacuum method.Should I use suction cups or suction plates?
Evacuation of sampling bottles with a portable vacuum pump
Leachate monitoring IRGO-Slovenia
Sampling bottle box with sampling bottles
Different suction cups and suction plates
For extracting soil water for chemical analysis pore water samplers with cup are used (qualitative analysis). Cups are easier to install than plates.
For determination of hydrologic loading of water and substances porous plates are suitable. Plates are enclosed by a cylinder to prevent that water will run around the plate (vacuum too low) or that water from a too large catchment span is extracted (vacuum too large). On lysimeter sites the cylinder reaches as far up as the soil surface. In contrary, leachate samplers are installed below the soil water shed.
For pore water samplers a bubble point of 100 kPa (= 1000 hPa) is standard. For leachate samplers a bubble point of 10 kPa (= 100 hPa) is sufficient.
The number of suction cups connected to one vacuum source is theoretically not limited, as the vacuum once applied will stay and only the volume of water must compensated by the volume of air from the vacuum pump.
In practise, we recommend to connect not more than about ten samplers to one vacuum unit for two reasons:
In the description of each sampler on the following pages you will find recommendations for the suitability.
Still, the chemical interactions of soil water with the porous material, the vacuum level and the method of storage are complex. Therefore, please contact us in case of doubt.
UMS developed a standard test procedure in co-operation with the Technical University Munich-Weihenstephan.
A data base for suitability of several samplers is available now!
For determination of hydrologic loading of water and substances porous plates are suitable. Plates are enclosed by a cylinder to prevent that water will run around the plate (vacuum too low) or that water from a too large catchment span is extracted (vacuum too large). On lysimeter sites the cylinder reaches as far up as the soil surface. In contrary, leachate samplers are installed below the soil water shed.
For pore water samplers a bubble point of 100 kPa (= 1000 hPa) is standard. For leachate samplers a bubble point of 10 kPa (= 100 hPa) is sufficient.
How many samplers in a system?
The number of suction cups connected to one vacuum source is theoretically not limited, as the vacuum once applied will stay and only the volume of water must compensated by the volume of air from the vacuum pump.
In practise, we recommend to connect not more than about ten samplers to one vacuum unit for two reasons:
- If only one leak occurs (broken cup or faulty connection) the complete vacuum system stops working.
- If at one point the soil is drier than the cup‘s bubble point, the complete system stops working.
- It is much easier to handle small systems
Which porous material should be used for which substances?
In the description of each sampler on the following pages you will find recommendations for the suitability.
Still, the chemical interactions of soil water with the porous material, the vacuum level and the method of storage are complex. Therefore, please contact us in case of doubt.
UMS developed a standard test procedure in co-operation with the Technical University Munich-Weihenstephan.
A data base for suitability of several samplers is available now!
Conditioning
We advise not to flush the ceramics with any acid solution, as this can destroy ceramics or change their chemical behaviour. Discard the first samples after installation.- Suction tubes should be as short as possible.
- Many air bubbles within the system reduce the vacuum.
- Shafts are marked so they can be installed in the optimal orientation.
Answers to FAQs
- Installation of cups, tubes and bottles in frost free depths only!
- Bottles and cups should be installed at the same level to prevent differing hydrostatic potentials.
- Water samples should be stored dark and at soil temperature, e. g. inside the UMS sampling bottle box.
- Carefully remove the organic layer before augering in the mineral soil layer.
Contact
Georg von UnoldTel: +49 89 12 66 52 - 15
Fax: +49 89 12 66 52 - 20
E-Mail: gvu@ums-muc.de
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