Historical Foundation of Plant and Groundwater Interactions - Introduction to Phytoremediation of Contaminated Groundwater - page 23

remained unanswered. Such unanswered questions had seri-
ous economic implications for most of the western United
States, because it had been hypothesized that a great propor-
tion of natural groundwater discharge from a particular basin
was due to the removal, through transpiration, of groundwa-
ter by plants. Hence, this amount of discharge had to be
quantified before estimates could be made of the amount of
groundwater that could be pumped at well fields without
overstressing the aquifer system or affecting the ecological
aspects of the area. Moreover, similar questions would be
asked as the interaction of plants and contaminated ground-
water was investigated, especially to achieve hydrologic
containment or control.

what was called the 'groundwater habit' prior to the intro-
duction by O.E. Meinzer of the now widely-used term phre-
atophyte. It also was shown empirically that certain plants
grow roots to the water table and capillary fringe and use
groundwater to meet transpiration demands. This use of
groundwater results in a measurable fluctuation in the
water-level in wells.
Why is this information important to the phytore-
mediation of contaminated groundwater? These early
observations provide an unbiased confirmation that plants
and groundwater interact. This historical perspective is
essential to those environmental professionals who either
have to implement or regulate phytoremediation projects
that involve contaminated groundwater. A chronology of
important events in plant physiology and hydrogeology is
provided in Table 1.3 to support the almost 100-year-old
observation of plant and groundwater interactions.

1.3 Summary

Plants require water and, for some plants, this need can be
met by groundwater. As early as the 1920s, it was clear that
certain plants in arid regions of the United States possessed

Table 1.3 Timeline of important events in plant physiology and hydrology which provides a basis to support the fundamental interaction of plants
and groundwater (References are found in the text of Chaps. 1 and 2).
Date

Significant events in plant physiology Significant events in hydrology

300 BC Aristotle stated that plants use only soil for growth (Humus Theory).
Theophrastus recorded more than 500 plant names in his
Enquiry into Plants and On the Causes of Plants .

250 Archimedes stated principles of floatation.

50 AD Pliny the Elder lists up to 1,000 plants in his 37-volume

Natural History.

1398 English parliament passed laws to prevent pollution of English

rivers.

1569 One of the earliest publications on water dowsing was written by J.

Besson.

1580 Palissy's Discourse Admirables was published and discounted the

popularly held notion that seawater returned to the highlands by
underground passages.

Andrea Cesalpino stated in his Des Plantis libri XVI that
plants absorb water similar to a sponge absorbing water,
rather than by forces of magnetism or suction.

1583

1620 J.B. van Helmont provided evidence that plants take up

significant quantities of water rather than soil, which
discounted the Humus Theory, and confirmed speculations
made earlier by Sir Francis Bacon.

1653 Pascal stated that a fluid exerts an equal pressure in all directions.

1665 Robert Hooke used a crude microscope (30X) and called

empty holes of dead cork tissue “cells”, in Micrographia.

1667 John Ray classified 18,600 species of plants; divided

angiosperms into monocotyledons and dicotyledons.

1670 Anton van Leeuwenhoek, built the first useable

microscope, which could magnify up to 300X.

1674 Perrault determined the water budget, P-ET ¼ R, in Treatise On

The Origin of Springs.

1675 Marcello Malpighi experimentally determined that water
was transported to the leaves through the xylem,
as published in Anatome Plantarum.

(continued)