Food Biochemistry and Food Processing

5 Water Chemistry and Biochemistry 131

water must be considered in order to take advantage
of microwave cooking.

WATER RESOURCES AND THE
HYDROLOGICAL CYCLE

Fresh waters are required to sustain life and main-
tain living standards. Therefore, fresh waters are
called water resources. Environmentalists, scien-
tists, and politicians have sounded alarms about lim-
ited water resources. Such alarms appear unwarrant-
ed because the earth has so much water that it can be
called a water planet. Various estimates of global
water distribution show that about 94% of earth’s
water lies in the oceans and seas. These salt waters
sustain marine life and are ecosystems in their own
right, but they are not fresh waters that satisfy
human needs. Of the remaining 6%, most water is in
solid form (at the poles and in high mountains be-
fore the greenhouse effect melts them) or under-
ground. Less than 1% of earth’s water is in lakes,
rivers, and streams, and waters from these sources
flow into the seas or oceans. A fraction of 1% re-
mains in the atmosphere, mixed with air (Franks
2000).
A human may drink only a few liters of water in
various forms each day, but 10 times more water is
required for domestic usages such as washing and
food preparation. A further equal amount is needed
for various industries and social activities that sup-
port individuals. Furthermore, much more is re-
quired for food production, maintaining a healthy
environment, and supporting lives in the ecosys-
tems. Thus, one human may require more than 1000
L of water per day. In view of these requirements, a
society has to develop policies for managing water
resources both near and far as well as in the short
and long terms. This chapter has no room to address
the social and political issues, but facts are presented
for readers to formulate solutions to these problems,
or at least to ask questions regarding them. Based on
these facts, is scarcity of world water resources a
reality or not?
A major threat to water resources is climate
change, because climate and weather are responsi-
ble for the hydrologic cycleof salt and fresh waters.
Of course, human activities influence the climate in
both short and long terms.
Based on the science of water, particularly its trans-
formations among solid, liquid, and vapor phases

under the influence of energy, we easily understand

that heat from the sun vaporizes water from the

ocean and land alike. Air movement carries the

moisture (vapor) to different places than those from

which it evaporated. As the vapor ascends, cooling

temperature condenses the vapor into liquid drops.

Cloud and rain eventually develop, and rain erodes,

transports, shapes the landscape, creates streams and

rivers, irrigates, and replenishes water resources.

However, too much rain falling too quickly causes

disaster in human life. On the other hand, natural

water management for energy and irrigation has

brought prosperity to society, easing the effects on

humans of droughts and floods, when water does not

arrive at the right time and place.

Water is a resource. Competition for this resource

leads to “water war.” Trade in food and food aid is

equivalent to flow of water, because water is re-

quired for food production. Food and water manage-

ment, including wastewater treatment, enable large

populations to concentrate in small areas. Urban

dwellers take these commodities for granted, but

water enriches life both physically and mentally.

ACKNOWLEDGMENTS

The opportunity to put a wealth of knowledge in a

proper perspective enticed me to a writing project,

for which I asked more questions and found their

answers from libraries and the Internet. I am grateful

to all who have contributed to the understanding of

water. I thank Professors L. J. Brubacher and Tai

Ping Sun for their reading of the manuscript and for

their suggestions. I am also grateful to other scholars

and friends who willingly shared their expertise.

The choice of topics and contents indicate my limi-

tations, but fortunately, readers’ curiosity and desire

to know are limitless.

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