Integrated Field Lysimetry and Porewater Sampling for Evaluation of Chemical Mobility in Soils and Established Vegetation

The overall goal of this procedure is to demonstrate field ly symmetry and soil pour water sampling techniques used for analyzing the fate of chemicals applied to soils and established vegetation. This is accomplished by first installing lysimeters into soils in an area with little to no slope. The second step is to install the pour water samplers to a desired depth within the lysimeters.

Next, the chemical application is made following a two week acclimation period. The final step is sampling poor water, soil, and foliage to determine chemical distributions at specific evaluation dates after treatment. Ultimately, integrated field lily symmetry and poor water sampling provide valuable tools for establishing distributions and potential risks of chemicals in the environment.

The main advantage of this technique over existing techniques such as greenhouse O symmetry, laboratory based methods, and other soil core methods, is that this technique is both applicable in the real world and allows for the quantification of chemical distribution and mass balance. Visual demonstration of this method is critical. As field installation and exhumation steps can be difficult to learn, and this procedure requires specially adapted equipment Begin by choosing an appropriate experimental site.

The site should have soil and vegetation, properties of interest, and little or no slope. This study used both an established turf grass system and bare ground. For vegetated plots, pull vegetation plugs where lysimeters will be installed.

Next, ready One of the lysimeters For this protocol, they are made of rolled and welded 18 gauge steel sheets. Use an inverted post driver to drive the lysimeters into the prepared sites. Leave about one to two centimeters of each lysimeter above the soil surface.

With lysimeters in place. Replace any vegetation plugs. Next, install pour water samplers into the installed lysimeters.

To do this position, a 2.5 centimeter diameter steel rod at the center of the exposed lysimeter opening. Then use a mallet to drive the steel rod to the desired pour water sampler depth. Once the depth is reached, remove the rod to expose the hole for the sampler.

The next step is to make a slurry of irrigation water and chemically inert silica flour and thoroughly mix it after thoroughly mixing the slurry ready a sampler. This sampler is made of quartz and PTFE. Place the sampler in the mixture.

Attach a portable vacuum pump to the sampler and apply a pressure of negative 50 to negative 70 kilo pascals. When 10 minutes have passed, remove the sampler and disconnect the pump thoroughly. Mix the slurry again.

Then place a 2.5 centimeter diameter tube connected to a funnel into the hole made with the rod. Pour 60 milliliters of the slurry into the bottom of the hole. When done, remove the tube and funnel to place the sampler.

Use a plastic or metal pipe that can fit into the hole and reach to the needed depth Properly. Orient the sampler at the end of the pipe with its tubing threaded into the interior. Use the pipe to push the sampler into the hole at the desired sampling depth.

At this point, ensure that the tubing from the sampler extends out of the hole. Next, use a slurry of non-treated native soil to backfill the hole to its original level. Replace any vegetation at the top of the hole.

Next, prepare the collection system. Use a section of fluorinated ethylene propylene tubing to attach the sampler tubing to a vacuum bottle. Use more FEP tubing and a plastic tube clamp to connect the vacuum bottle to the vacuum pump.

As a test, apply vacuum pressure of negative 50 to negative 70 kilopascals to the system, and then clamp it for this study. Cover the collection bottles with black plastic to prevent photo degradation with the lysimeters and pour water samplers in place. Follow a predetermined management plan that is identical for the bare ground and vegetated plots for the duration of the experiment.

After two weeks of acclimation and before chemical application, collect background, pour water samples to collect samples the day before or day of collection. Apply about negative 50 to negative 70 kilopascals of vacuum to the pour water sample vacuum bottles to draw water in. Later, measure the volume of the collected water by pouring it into a graduated cylinder.

After measuring the water volume, pass it through a filter at the end of a syringe into a storage container. Keep samples on ice or in a refrigerator until analysis. Now, apply the chemical of interest on the surface of the plot following typical methods and use patterns.

Leave some lysimeters untreated to service controls After chemical treatment, follow a predetermined poor water collection schedule. At each collection, measure, filter, and store the collected water for analysis. Soil sample collection occurs at predetermined evaluation dates after chemical application.

To retrieve the lysimeters, use barrel clamps attached to a tractor implement Position the bucket to allow the clamps to be placed onto the lysimeters exposed edge. Lift the implement to exhume the lysimeter column out of the soil. Once exhumed cap, the lysimeter ends with fitted insulation sheets.

Hold the caps in place with gallon size polyethylene bags over the lysimeter ends and secure with duct tape Transport exhumed lysimeters to a field laboratory. Use a reciprocating saw with a metal cutting blade to cut the lysimeter lengthwise from the bottom to the top on one side. When a lysimeter is split open, use metal dividing plates to separate discrete soil and vegetation samples.

Prepare appropriately labeled sample bags and excavate the sections with spoons and spatulas. Avoid soil directly in contact with the lysimeter Store the sample bags on ice in the field laboratory and during transport. This plot has depth along its vertical axis and arsenic concentration on its horizontal axis.

It shows the initial depth profile of arsenic concentrations in non-treated Bermuda grass, the blue circles and non-treated bare ground. The black circles here are the depth profiles. 36 days after application of MSMA, the profile for treated turf grass is given by the red triangles that for treated bare ground uses the black triangles.

The circles are as before over the course of a year. It was found that MSM concentrations in treated lysimeter samples were elevated in comparison to non-treated samples to a depth of 10 to 15 centimeters. No significant differences between treated and non-treated samples were found at greater depths.

The poor water concentration of arsenic in MS MA treated plots varies with the depth. At 30 centimeters dissolved arsenic concentrations were above 10 micrograms per liter. The EPA drinking water contaminant limit over the duration of the study.

The concentrations increased immediately after MSMA application and subsequently decreased over time. In contrast, poor water collected from a depth of 76 per two centimeters had arsenic concentrations that were similar to background levels and consistently below the EPA limit. While attempting this procedure, it’s importance to devise a scientific plan based on your research objectives.

For example, in our current study, we use a sandy soil to investigate a worst case scenario for chemical leaching with respect to soil texture. After watching this video, you should have a good understanding of how to install and utilize field less symmetry and pull water sampling to determine the environmental fate of chemicals applied to soils and establish vegetation.