Alex Chow

1. PIs: Alex T. Chow, Geoff G. Wang (Clemson University); Randy A. Dahlgren (UC Davis), Carl C. Trettin (USDA Forest Services), Po-Keung Wong (CU Hong Kong )
Students: Jun-Jian Wang, Thomas A. Coates, Mary C. Rogers, Kuo-Pei Tsai (Clemson University), Tsz-wai Ng (CU Hong Kong)
Impacts of Prescribed Fire on Polycyclic Aromatic Hydrocarbon Production and
Contaminant Photo-transformation Reductions in Coastal Plain
Grant # SCN-2013-02784
Polycyclic aromatic, charcoal rich,
& recalcitrant black C
Lignin, polysaccharide rich &
relatively degradable C
Facts: Forest fire modifies the chemical composition of the detritus layer
on the forest floor
Study Questions:
1) Can we control dissolved black carbon (BC) production and export
through effective prescribed burn practices?
2) How does dissolved BC affect downstream biogeochemical processes
and fates of contaminants of emerging concern?
Introduction
●OH H2O2
1O2 3DOM*
CECs
Terrestrial DOM
Study Approach
Prior to and immediately after burning, Brown’s Planar Intersect Method (Brown
1974) was used to determine fuel loading in each treatment area. In addition,
understory vegetation, fuel bed depth, duff thickness, and duff thickness were
measured. Detritus materials were collected for chemical characterizations and
sunlight simulated study.
Images before, during, and after the annual growing season fire treatment. Yawkey Wildlife Center Heritage
Preserve in Georgetown, SC.
Controlled Field Study
During the 2014-2015 field season, fifteen experimental units were established on
the Yawkey Wildlife Center Heritage Preserve in Georgetown, SC. The units were
randomly assigned to one of five treatments, affording three replicates per
treatment that contained 6 plots. Five treatments established: Unburned control,
annual dormant season burning, annual growing season burning, biennial dormant
season burning, and biennial, growing season burning. The annual dormant season
treatment was conducted on March 9-11, 2015 and the annual growing season
treatment was conducted on May 5-6, 2015. Soil moisture, fuel moisture, fire
weather were monitored, and the conditions along with temperatures from vertically
and horizontally placed type-K thermocouples.
Controlled Laboratory Study
Litters of Ponderosa Pine were burnt in muffle furnace in different temperatures and
oxygen availability. Water extracts from burnt litters were irradiated in simulated
sunlight up to 72 hours.
50 oC 250 oC
- Air + Air - Air + Air
400 oC
0 hr
6 hrs
24 hrs
48 hrs
72 hrs
Field Incubation Study:
Purpose: To determine temporal variation of the quantity and quality of
DOM leached from burned materials
Design: Twenty-five custom 2ft x 2ft aluminum trays with a drain hole to
glass carboys have been built. Trays filled with known amount of detritus
materials will be incubated in field conditions for at least 6 months.
Watershed Monitoring:
Purpose: To determine landscape process of DOM export in burnt
watersheds
Design: An experimental watershed in Francis Marin National Forest is
scheduled an aerial burn in Spring 2016. Soil and water samples will be
collected prior and after the burn.
Experiments in Years 3 and 4 Products
Wang JJ, Dahlgren RA, Ersan M, Karanfil T, Chow AT (2015) Wildfire altering terrestrial precursors of
disinfection byproducts in forest detritus. Environmental Science & Technology 49: 5921-5929.
Ng TW, Chow AT, and Wong PK (2014) Duel roles of dissolved organic matter in photo-irradiated Fe(III)-
contained waters. Journal of Photochemistry and Photobiology A: Chemistry 290: 116-124.
Majidzadeh H, Wang JJ, and Chow AT (In Press) Forest fire alters dissolved organic matter and disinfection
byproduct precursors exports from forested watersheds – Part I: A controlled laboratory study. In,
Occurrence, Formation, Health Effects, and Control of Disinfection Byproducts. Karanfil et al. Eds., American
Chemical Society Symposium Book.
Tsai KP, Rogers MF, Chow AT, and Francisco Diaz (In Press) Forest fire alters dissolved organic matter and
disinfection byproduct precursors exports from forested watersheds – Part II: A controlled field study. In,
Occurrence, Formation, Health Effects, and Control of Disinfection Byproducts. Karanfil et al. Eds., American
Chemical Society Symposium Book.
The research team is applying both control studies and field investigations in the study. There
are three major research experiments in the proposed program: I) Controlled Field Study, II)
Controlled Lab Study, and III) Experimental Watershed, corresponding to the management
practices, roles of dissolved organic matter (DOM), and landscape processes, respectively.
The controlled studies, including Controlled Field Study (Experiment I) and Controlled Lab Study
(Experiment II), are to quantify the production and export of polycyclic aromatic hydrocarbons
(PAHs) and dissolved BC under different management practices and to investigate the roles of
dissolved BC controlling the fate of PAHs and other contaminants of emerging concern (CECs).
Experimental plots with different burning schedules and frequency have been established at
Yawkey Wildlife Center in Georgetown, South Carolina. Detritus materials are collected from
the experimental plots for field incubation.
Fluorescence emission-excitation matrix of water extracts from burnt litters after irritated from different
times.
Custom-made aluminum tray will
be used in field incubation study