Author: Supasiri RittironPublisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 0
Book Description
Increase in contaminants in soil caused by wildfires is poorly understood, despite it being a significant source of pollutants to receiving waters and reservoirs (Abraham et al., 2017). This study assesses the potential longer-term impacts of a small-scale wildfire that occurred in September 2018 on soil and leachate chemistry in the San Gabriel Mountains, Los Angeles County, California. Soils were collected from five sites within the burned and unburned areas in March 2019, following the post-fire runoff, for sediment and total element analyses. Batch leaching tests were conducted at different temperatures to determine the extent of size partitioning and mobilization of the major (Na, Mg, Al, K, Ca, and Fe) and minor/trace (Mn, Cu, Zn, Cr, and As) elements in order to understand solute transport as a result of changes in chemical bonding and physical characteristics of the soils. The results showed that burned soils were relatively finer than the unburned soils. For soil chemistry, the burned and unburned soils had similar composition of major and minor elements with the average range of the four interested minor elements being between 105 and 1,250 ppm, except As (4 ppm). Nevertheless, the batch leaching tests showed burned soils had significantly higher concentrations for some elements (e.g. Mg and Ca by more than six-fold and sevenfold, respectively, compared to that of the unburned soils within four-week period). These results potentially imply that size partitioning and the rate of the elements released into the water, could be impacted. Chromium amended experiments showed the opposite trend with Cr(VI) concentrations decreasing over time for both burned and non-burned soils. The was likely due to sorption of Cr(VI). These results would be valuable for predicting the fate of the contaminants and broader impacts could also include more effective pre- and post-fire mitigation plans.
