INSERT YOUR
ORGANIZATION’S
LOGO HERE
4 : Earth Materials at the Foundation : Geologic Factors that Effect Human
Health
Jody Berg, Western Oregon University
Faculty Sponser : Steve Taylor, PhD
Abstract
The Earth’s crust is comprised of
rock materials, which in turn is
composed of inorganic silicate
minerals. Rock material decomposes
at the Earth’s surface to form regolith
via
chemical
and
physical
weathering. Regolith forms the basis
of soil and the fundamental
framework for life in the critical zone,
at the interface of the hydrosphere,
atmosphere, and geosphere. Soil
forms via physical, chemical, and
biological transformations over time.
As a result of pedogenic process,
elements are released into surface
and groundwater, and subsequently
become available as part of macroand micro- nutrients in the food chain
with plants at the foundation.
Essential macro-elements derived
from the lithologic environment
include Ca, Mg, Na, Cl, K, P, and S.
Lesser abundant, but still important
nutrients include Mn, Fe, Co, Cu, Zn,
and Se. Deficiencies and surpluses
of nutrients in the food chain effect
physiological function of both animals
and humans. Thus an understanding
of geological variables in terrestrial
ecosystems is essential for regional
public health studies. This paper
examines the effects of Earth
materials and related near- surface
processes on human health.
Case Studies
Introduction
Soil plays an important role in the transport of
minerals. Soil is formed from physical/chemical
weathering of rocks to regolith. When regolith
interacts with plants, microorganisms, and soil fauna
it becomes soil. (Alloway). The soil type in an area
will dictate whether it will have abundant essential
minerals or trace essential minerals. Both of these
groups of minerals are essential for life on Earth.
An abundance of a specific mineral in an area could
lead to toxicity in the human population and the
animal/plant population. This is a large concern for
trace minerals which are ok at small and moderate
concentrations, yet at higher concentrations will lead
to toxicity in humans. The lack of trace minerals all
together though will lead to a deficiency. This could
be due to the fact that they are essential to the
overall health of people. Both the essential abundant
minerals and essential trace minerals are important
to the over function and wellbeing of humans and
animals alike. With an increased amount of mineral
intake, or lack there of, it will lead to health
problems.
Once soil produces plants it is capable of concentrating
various chemical elements. (Komatina)
The plants that live in the soil are able to lift elements out
of the lower horizons and transport them to the upper
horizons. (P, S, Ca, K, and many of the trace elements.)
(Komatina)
•Horizon A : rich in organic matter & organisms.
Accumulation of humus & many elements in upper part.
•Horizon B : via infiltration of water, clay & iron minerals
accumulate in it. Elevated content of Cu, Ni, Zn, Pb, &
other.
•Horizon C : represents loose and partially weathered rock
mass. (Komatina)
Figure 2 represents the different soil horizons and what is
commonly found in them.
Figure 2. Soil Horizons
Cadmium and Lead are the elements in
contaminated soil that are said to introduce the
greatest health risks.
•In London there is a great exposure to lead in
garden soil. This is because of the lead based paint
that was widely used. Although the lead infiltrates
the plants it doesn’t effect them. Most humans are
effected by lead via dirt more so than the plants
themselves. This is contributed to eating the dirt
accidently. (figure 5 shows an effect of lead
poisoning.
•In China paddy rice crops are grown near a river.
This river and the paddy crops themselves are
exposed to a high rate of cadmium. When the
paddies are dried out the Cadmium ion is absorbed
at fast rates. When people eat this they are exposed
to cadmium toxicity. It mostly effected elderly women
who had had many children. The disease is called
itai-itai disease. The average concentration of
cadmium found on the paddies was more than 10x
the amount that should be taken in per day.
(Alloway) (figure 4)
Soil Forming Process
Break down of rocks and formation of sediment
(figure 1) :
• Chemical weathering
Figure 4 : A person suffering
from itai-itai disease.
Case Studies
• Mechanical and Physical weathering
Regolith is formed as a result of the decomposition
of rocks. When regolith is joined by organic
material it becomes soil.
Soil represents a natural mixture of :
Acute deficiencies of trace elements in plants can
result in :
• Inorganic mineral material
•Chlorosis (figure 3)
• Living and dead organic substances
•Reduced dry matter growth & yield.
• Air & water. (Komatina)
India is a large country which the soil suffers from
mineral deficiencies. 45% deficient in zinc, 33% boron,
8.3% iron, 4.5% manganese, & 3.3% copper. This is
because the soil in this particular region can not
support some essential elements.(Alloway)
•Visible symptoms of stress
Contact
Conclusion
Figure 5 : An albatross suffering
from droopwing, which is an effect
of lead poisoning.
Soil is the key element in the transport of abundant
essential and trace minerals to not only humans but
animals as well. With looking at the soil in a particular
area it is possible to establish whether or not the soil in
that area contains the minerals and in what amount.
There are ways to avoid deficiencies of elements and
toxicity. This is to look at the plants growing in such
areas and make an observation on whether they contain
the concentration in the edible part or other parts. With
looking at soil content and plant life it is possible to
avoid deficiencies and toxicity in human life.
References
Jody Berg
Dept. Earth and Physical Sciences
Western Oregon University
jberg08@wou.edu
Figure 1 : Rock Cycle : shows the effect of both weathering processes.
Alloway, 2005, Bioavailability of Elements in Soil, in Selinus, 2005
Komatina, 2004, Chapter 2 – Overview Geological Factors that Effect Human Health
NRC, 2007, Chapter 2 – Earth Processes and Human Physiology
NRC, 2007, Chapter 6 – Earth Perturbations and Public Health Impacts
Skinner, 2005, Mineralology in Bone, in Selinus, 2005
Figure 3 : Iron deficiencies in plants will turn the leaves this yellow color.