The big idea of what we are looking at... #thinlayerplacement
As sea level rises, our coastal marshes are drowning. One restoration technique that people have been developing-particularly on the Gulf of Mexico- is thin layer placement, simply putting a thin layer of sediment on the marsh to increase the elevation. The layer is thin enough that plants can grow through and hold the new sediment in place!
With #thinlayerplacement , #dredge material is usually used as the sediment layer. Dredge is sediment that has been removed from the bottom of a river/marina to deepen the channel for boats.
In our overarching experiment, we are looking at other types of sediment that could be used-like sand and loam. We are gathering data on plant growth and soil/water chemistry at each of our sites.
The #dredge used in #thinlayerplacement can have some issues. Because it’s taken from the bottom of water bodies it has the potential to become acidic once it is exposed to air. This is due to the sulfides present in the soil becoming oxidized. Sulfides and acidity can prevent plant growth in #thinlayerplacement
This is why our overarching experiment is looking at other available sediment. However, I am running another experiment to test things we can mix into the dredge material to fix the sulfide/acid problem.
My experiment ran for 16 weeks (Ending right at the beginning of December 2021). In this experiment, I cared for 42 soil cores (some in the picture) with various things mixed in. I am looking to see what different materials we can mix in that could offset a high pH and sulfidic soil-because these are bad for plant growth.
I’m experimenting with #gardenlime #recycledconcrete#crushedshells and #mulch as potential additives.
In my #experiment I’m looking at mixing four different materials with #dredge in order to offset the acidity and
sulfides in #thinlayerplacement
The first is red mulch. The red in red mulch comes from iron oxide. Iron oxide can bind with sulfide in the soil, preventing it from becoming toxic to plants!
The second is #recycledconcrete. Cement (what concrete is primarily made of) is made out of calcium oxide and also has iron oxide in it. Calcium can balance out an acidic soil (just like tums in your stomach!).
I am trying two other things with calcium, #crushedshells and #pelletizedlime both of which are made of calcium carbonate.
I mixed each of these materials with dredged sediment and am monitoring how the soil chemistry changes with time!
I take porewater samples from my #soil columns! These samples will help me understand what is going on in the soil-is there lots of sulfide or iron? What’s the #ph ? Porewater samples help me answer these questions!
To take #porewater samples, I have installed a lysimeter in the columns. They are made of a porous, ceramic tube that will suck the water out of the soil when a vacuum is formed with a syringe. We connect the syringe and lysimeter by screwing them together (officially called a #luerlocksystem).
