Abstract: In this project we will quantify the extent of desalination caused by hay added to brine-contaminated sites. Two recent spill sites will be broken into plots that will receive tilling, tilling + hay, tilling + fertilizer, or tilling + hay + fertilizer. The results from the field sites will be compared to the results from microcosms receiving the same treatments. The microcosms will have controlled moisture, aeration, and nutrients to maximize the microbial activity.
We will sample the sites and microcosms to determine the mechanism(s) responsible for the desalination. We have proposed three mechanisms. The first mechanism is a purely physical effect: the hay provides pores for water to enter the soil and leach salt components away. The second mechanism is a purely chemical effect: compounds formed during the decay of the hay can exchange cations with the clay, releasing sodium. The third mechanism is both physical and chemical: molecules formed during the decay of hay or formed by microorganisms can bind the clay particles into water-stable aggregates. All mechanisms improve the permeability of the soil, allowing water to flush salt from the soil. The first mechanism should dominate early in a remediation project. The second and third mechanisms should become more important as the hay decays. Microbial action is important to all three mechanisms: biodegradation of the hay will decrease the rate of the first and increase the rates of the other two proposed mechanisms.
We will perform several analyses on the soils. We will monitor the concentrations of cations and anions in the soil to determine the desalination rate. We will perform permeation analyses to see if we are improving the permeability of the soil. We will determine the cation exchange capacity and the aggregate stability of the soil. In addition, we will monitor the total biomass and diversity of microorganisms with phospholipid fatty acid analysis to determine what microorganisms, if any, are responsible for the remediating effect of hay addition.
In this project we hope to demonstrate the effectiveness of using hay to remediate a brine spill and determine the mechanism(s) of this remediation.