Green house set up in 2012
 .
Overview:
This experiment examines the direct foliar effects of acute,
short-term exposure to simulated acid rain (SAR) on seedlings
of three domesticated plant species: sunflower, radish, and clover.
Simulated acid rain of pH 3.5 and pH 2 (tapwater acidified with
a 2:1 molar ratio of sulfuric:nitric acids) is sprayed onto the
above-soil foliage of 10 day old seedlings once daily to completely
wet the foliage and moisten the soil surface for a total of 18-20
daily applications. The controls are similarly treated with plain
tap water (typically ~pH 6.8-7.4). The seedlings are watered
to soil saturation once daily with tapwater either several hours
before or after treatment application.There are 18 replicates
(pots of seedlings) per species per treatment group in 2012.
Upon completion of the treatment phase, the plants are measured
for stem length and leaf area, dry biomass per plant, the proportion
of plants that exhibit any damage (dead cells, lesions, spotting,
etc.), and the percent leaf area exhibiting damage. Leaf wettability
is examined by placing drops (20-30 ul) on the leaves and observing
retention and drop shape (contact angle). Leaf samples are also
prepared and viewed using a scanning electron microscope to document
microscale effects on tissues, surface structures, and epicuticular
wax (view
poster of 2008 experiment SEM images).
Seedling
Establishment 2011 (1/25/12 - Day 1 SAR application)
Day 7 of SAR Applications
(2-1-2012)
Click the individual
images to see larger overview of plants in each treatment group.
Day 14 of SAR Applications
(2-7-2012)
Click the individual
images to see larger overview of plants in each treatment group.
Appearance at data collection
(2-13-2012)
SAR applications were stopped
on Feb 12th, 2012.
Click the individual
images to see larger overview of plants in each treatment group.
NOTE: Images say Day 13,
it is actually day 20 of SAR treatment period (18 applications)
Droplet formation images
ARCHIVAL PHOTOS OF TYPICAL
EFFECTS OF SIMULATED ACID RAIN IN THIS EXPERIMENT
Following are detail shots
of the typical physical effects of the acid treatment on the
pH 2 plants. These photos are from various years, but typify
direct effects we see routinely in this experiment.
pH 2 sunflower with true leaf petiole
growing from cotyledon position on stem. |
Abnormal leaf development in sunflowers.
These were seen in pH 3.5 and control. |
Same as above. |
Sunflower pH 2 stem lesions day 19. |
|
Scanning electron micrograph of acid burn
on a sunflower leaf treated with pH 2 simulated acid rain.
|
|
2011 Bates College
Modified on 1-4-2011 GA
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