Historical Foundation of Plant and Groundwater Interactions - Introduction to Phytoremediation of Contaminated Groundwater - page 4

• What plants use groundwater? Do they use other sources
of water? Can these plants be used at contaminated sites?
(Chaps. 1 and 7)
• How do some plants survive in areas characterized
by high concentrations of organic solutes? (Chaps. 12
and 13)
• What solutes can be taken up by plants? Can
contaminants in the dissolved or gaseous phases be
taken up by plants? (Chaps. 11 and 12)
• What happens to contaminants after they enter plants? Is
contaminant volatilization from plant leaves a decrease or
increase in exposure risk? (Chap. 13)
• How long will it take for plants to decrease groundwater
contaminants to acceptable levels? (Chaps. 13 and 15)
The historical separation that has existed between the
disciplines of plant physiology and hydrogeology may
explain why many of these questions have not been
answered to the full satisfaction of practitioners of either
field, particularly with respect

germination and growth of undigested seeds in waste-
disposal areas. This establishment of a stable supply of
plants, or crops, has been implicated by historians as one
of the prerequisites for the subsequent establishment of
civilization and the development of the arts and sciences.

1.1.1 The Natural Philosophers

The importance of plants to human survival has led to their
being a subject of speculation and investigation. Aristotle
(384-322 BC ) proposed that plants were totally dependent
upon the soil based on observation rather than experimental
testing. Aristotle deduced that plants grew in soil, or humus,
and, therefore, plants must be dependent upon humus for
their survival. Aristotle stated that plant roots took from the
soil miniature versions of their organic matter and came to
be known as the Humus Theory. The legacy of this theory
can be seen today in the marketing of plant 'food' by
companies that make various soil amendments. The Humus
Theory fit Aristotle's view that terrestrial things consisted of
a combination of the four elements—fire, water, wind (air),
and earth. This idea of the four elements had also been
proposed by Empedocles of Agrigentum (492-432 BC ).
Even though plants were later shown to synthesize their
own food, Aristotle was not entirely wrong with his idea of
humus uptake, as will be shown later.
A student of Aristotle, Theophrastus of Eresus
(372-287 BC ) also known as Ferguson, recorded more than
500 plant names in his Enquiry into Plants (Loeb Classical
Library 1916) and On the Causes of Plants (Loeb Classical
Library 1990), considered to be the first written record about
plants . The name Theophrastus, which means god's speech,
was given to him by Aristotle. Theophrastus is often referred
to as the Father of Botany. In the first century AD , Pliny the
Elder (23-79 AD ) also known as Cais Plinius Secundus,
became interested in plants while a soldier in the Roman
army. During his tours of duty, he noted that the distribution
of plants seemed to be related to differences in climate; was
he perhaps the first plant ecologist? Again, these differences
were based on observation rather than experimentation.
Pliny the Elder went on to list up to 1,000 plants in his 37-
volume Natural History (Loeb Classical Library 1938) in the
year 50 AD . In 1596 the Swiss botanist Gaspard Bauhin
published Illustrated Exposition of Plants which contained
about 6,000 plants (Hobhouse 2004).
Plants also were recognized in ancient times for
containing strong chemical substances. For example, toxic
plant extracts have played a role in hunting and human
conflict for thousands of years. In ancient Greece, for exam-
ple, an extract of hemlock was the poison of choice, as those
familiar with the death of Socrates remember. Theophrastus

to the restoration of

contaminated environments.
Ultimately, the success of the phytoremediation of
contaminated groundwater must be based on scientifically
defensible and reproducible data that indicate that plants
fundamentally interact directly or indirectly with groundwa-
ter. The goal of Part I, which consists of five chapters, is to
present data that document that plants do interact with
groundwater. Without such observations, particularly of
the effect of plants on groundwater hydrology, phyto-
remediation might be incorrectly considered an extension
of bioremediation processes based on the use of non-
photosynthetic heterotrophic microorganisms to degrade
contaminants.

1.1 Plant Physiologic Contributions

The study of plant-water relations encompasses a long
period of history that can be traced back to many early
cultures. This is because plants have been and remain impor-
tant throughout everyday life as sources of food, fodder, and
medicine. The study of plants, or botany (from the Greek
botana , meaning pasture, grass, or fodder), can be traced
back to the times before Christ ( BC ). Prehistoric man through
trial-and-error probably recognized which plants could be
eaten with no ill effects, which plants might cause harm,
and which plants could be used to alleviate suffering. For
example, the use of plants for medicinal purposes was
recorded by the Sumerians as early as 3,000 BC The selection
of seeds of desirable plants to secure a more controlled
supply of food, medicine, or source of fermented beverages
safer to drink than ambient water supplies probably was not
a conscious decision, but arose from observations of the