The Direct Effects of Simulated Acid Rain (SAR) - 2017 Experiment


 
Greenhouse set up in 2017

SEM photo gallery - 2017 experiment

 

Overview: This greenhouse-based 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. The photo above show the typical arrangement of plants during the experiment. At least once during the treatment phase the treatment groups are shifted between tables and the pots randomized to some extent. 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 20 daily applications. The controls are similarly treated with plain tap water (typically ~pH 6.8-7.4). The seedlings are also watered once daily with tapwater either several hours before or after treatment application.There are 16 replicates (pots of seedlings) per species per treatment group in 2017. Upon completion of the treatment phase, the plants are measured for 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 water drops on the leaves to observe 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 2016 experiment SEM images).

Seedling Establishment 2017 (1/23/17 - Day 1 SAR application)


Click image to see full size.

 

Day 12 of SAR Applications 2-3-2017

 CLOVER

 

 Control Overview

 pH 3.5 Overview

 pH 2 Overview

 Control Side view

 pH 3.5 Side view

  pH 2 Side view
RADISH

 

 Control Overview

 pH 3.5 Overview

 pH 2 Overview

 Control Side view

 pH 3.5 Side view

  pH 2 Side view
SUNFLOWER

 

 Control Overview

 pH 3.5 Overview

 pH 2 Overview

 Control Side view

 pH 3.5 Side view

  pH 2 Side view
 

 Day 15 SAR applications - Feb 6, 2017.

Clover

 

Control overview  pH 3.5 overiew  pH 2 overview
Control wetted leaf  pH 3.5 wetted leaf  pH 2 wetted leaf

Radish

 

Control overview  pH 3.5 overview  pH 2 overview
Control wetted leaf  pH 3.5 wetted leaf  pH 2 wetted leaf

Sunflower

Control side view  pH 3.5 side view  pH 2 side view
Control wetted leaf  pH 3.5 wetted leaf  pH 2 wetted leaf
Control typical leaf appearance  pH 3.5 typical leaf appearance  pH 2 typical leaf appearance

 

 

Appearance at data collection (Feb 13-14, 2017)
Last SAR applications on Feb 12th, 2017. Total of 20 applications.

CLOVER
 
 Clover Control overview
 Clover pH 3.5 overview
 Clover pH 2 overview
 Clover Control whole view
 Clover pH 3.5 whole view
 Clover pH 2 whole view
   
 Clover pH 2 typical damage
  RADISH
 
 
 Radish Control overview
 Radish pH 3.5 overview
 Radish pH 2 overview
 Radish Control whole view
 Radish pH 3.5 whole view
 Radish pH 2 whole view
 Radish Control bolting plants
 Radish Control pH 3.5 plants
 >>>no bolting observed<<<
 SUNFLOWER
 
 Sunflower Control side view
 Sunflower pH 3.5 side view
 Sunflower pH 2 side view
Leaf fusion malformation - Control
 
 Typical effects at pH 2
     
 

Droplet formation images (from 2009 experiment)

 

 


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.

 SEM acid burn

Scanning electron micrograph of acid burn on a sunflower leaf treated with pH 2 simulated acid rain.

 

2017 Bates College
Modified on 1-5-2017 GA