Student Writing Handbook Fifth+Edition

Technical Report / 395

Welte, page 10

CONCLUSION

Summary of Findings

This investigation indicates that acid rain interferes with proper plant growth.

Possible Sources of Error

Even though every bulb was planted with at least one inch of surrounding area between

bulbs, some bulbs had slightly larger surrounding space. This situation may have caused

accelerated growth but would vary the obtained data only slightly.

Slight differences were recorded in the production of the artificial acid rain. The pH 4 solu-

tion actually ranged from 3.85 to 4.1; the pH 5 solution ranged from 4.9 to 5.1; and the pH 7

solution ranged from 6.8 to 7.0.

The use of sulfuric acid in preparing the rain solutions could cause slight differences in

the growth of the bulbs, but not in that of the ones watered with the pH 7 solution. The sulfuric

acid may produce differences from natural rain because natural rain is lowered to a pH of 5.6

from natural carbon dioxide in the air instead of from the sulfuric acid. The acidity in natural

rain is increased as a result of sulfur dioxide from man-made pollution.

Concluding Statement

The hypothesis was correct. The data showed that the growth of bulbous flowers is

deterred by water’s increased acidity.