Lead Levels in Roadside Soil
Aim
Background
Lead is a type of heavy metal and has an atomic value of 82. Of all
the known heavy metals in the earth’s crust, lead is the most abundant. It is
naturally all around us. Lead poisoning has been linked to many health issues,
the earliest reported in 370BC. It became a common illness in people working in
industries such as smelting, painting, plumbing and others in the 19th and 20th
centuries as these workers were exposed to lead pm a regular basis. (Wu
et al., 2011)
High exposure to lead can result in damage to most of a person’s
organs and organ systems including, kidneys, blood and the central nervous
system. It has the potential to be fatal. Even small doses of lead can damage a
person’s psychological and neurobehavioral functions (Wu
et al., 2011). Philip
J. Landrigan believes that unborn babies and young children are the most at
risk of permanent and untreatable damage as a result of exposure to lead. Lead
apparently “interferes with neuronal migration, cell proliferation and synapse
formation during critical periods of vulnerability” He claims that loss of
intelligence and behaviour are the result of this lead interference (2002).
There are many uses for lead in both chemical and metal compounds.
One of the compounds of lead is called tetraethyl lead. In 1922 tetraethyl lead
was added to petrol with the aim to improve the performance of engines and by
the 1970’s most petrol across the globe contained lead. After the damaging
effects of exposure to lead were found, along with the damage lead was doing to
cars, governments around the world started to take action to remove lead from
petrol. By 2002, lead was finally phased out in Australia and 80% of the total
sales of petrol was accounted for by unleaded fuel. (Landrigan,
2002)
Due to health concerns of the absorption of lead and the fact that
lead stays in soil for hundreds of years it is imperative that the level of
lead in the environment be monitored and exposure limited (where possible) for
the sake of public health.
Method
A road in a major capital city that had a high traffic flow was
identified. Two experiments were then done on the soil samples collected. In
the first experiment, soil samples were taken from a spot directly adjacent to
the road. The first soil sample was the surface sample. The following soil
samples were taken at depths of 5mm, 10mm, 15mm, 20mm and 25mm. These soil
samples were then analysed in a laboratory for the concentration of lead. This
test involved combining 3 grams of soil with 30 millilitres of HNO^3 for 1 hour
at 180 oscillations per minute. The sample was then centrifuged and the supernatant
analysed for lead using an ICP-AES (inductively coupled plasma atomic emission
spectrophotometer). (Regents of the University Of Minnesota 2016).The results
of the lead concentration were reported in ppm then converted to mg of lead per
g of soil for easy understanding (Figure 1).
In the second experiment, samples of the surface soil were taken
from the edge of the same road as experiment one and at distances of 5m, 10m,
15m, 20m and 25m extending into the neighbouring parkland. The samples were
then tested using the same process as experiment one. The results were then
converted to mg of lead per g of soil for easy understanding (Figure 2).
Results
Figure 1 shows that the deeper the soil, the lower the
lead concentrations, with the exception of the surface soil. The highest lead
concentration was found at 5 mm deep with a lead concentration of 0.26 mg/g of
soil. The lowest concentration of lead was 0.02 mg/g of soil at 25 mm deep.
Figure 2 shows that the further away from the road the soil
sample is taken, the less lead concentration there is in the surface soil
sample. The most lead was found at 0 m and had a lead concentration of 0.09
mg/g and the lowest found was at a distance of 25 m and had a lead
concentration of 0.01 mg/g.
Discussion
On the basis of analysis as
performed, it is discussed about the lead metal, its availability, uses,
hazards and its concentration in the soil at different layers. It is discussed
that lead is a chemical element with atomic number 82 and symbol Pb. It is very soft, malleable, ductile and poor
conductor of electricity. It is in the carbon group but behaves quite different
from carbon. It is discussed that lead as a metal is present in the environment
from thousands of years and it is one of the few elements known to ancient
people. Lead generally occurs as an ore
and rarely as a pure lead metal. It usually is found as an ore lead sulphide.
Also some other ores of lead are zinc, silver, cerrusite etc.
It is discussed that lead has
wide applications since 5000 BC. Lead is
generally used in pipelines, cables and also in paints and pesticides. Lead was
considered quite safe years ago for its numerous use but now it is understood
that it has damaging effects on health of humans and animals. It is highly toxic
and enters human body through water, food and air. Some fruits, vegetables, wine;
cigarette etc contains lead and through this lead enters our body. It enters
our body through drinking water when pipes corrode. It also enters our body when
lead fumes and dust are inhaled.
It was found in the early 19th
and 20th century that people working in smelting, painting etc
industry are more prone to health issues due to more exposure to lead on
regular basis. Though occupational exposure to lead was a concern but the major
concern found in late 1800 in Australia was risk of lead poisoning to children.
In children lead exposure and inhalation cause behavioural disruptions, brain
damage and it makes difficult for them to carry mental functions normally and
thus reduces their learning ability. Lead has the ability to affect brain and
kidney. It is very toxic and also causes anaemia, high blood pressures, kidney
and brain damage. It also reduces men fertility through sperm damage and in
women it leads to miscarriage and subtle abortions. It is so harmful that it
harms the nervous systems also. It also enters the mother’s womb through
placenta and affects the foetus. Thus it harms unborn children by harming their
nervous systems and brains.
It has become evident that lead
ends up in water and soil and thus affects water organisms and soil organisms.
Highways and farmlands are the areas where lead concentrations in the soil are
high and thus here soil functions are disturbed. Hence pertinent steps are being taken to reduce
the consumption of lead as it affects public health highly.
Road side traffic is one of the
main reasons for the lead accumulation in the soil adjacent to road. In order
to test the concentration of lead at different depth of soil roadside area is
considered where traffic is much as vehicles are one of the causes of lead
accumulation in the soil. It is evident from many sources that concentration of
lead reduces moving away from the road. Thus two experiments are conducted and
samples of soil are collected from the area directly adjacent to the road and
from the area little away from the road.
The conduct of the analysis
revealed significant level of finding with respect to the application of lead
and the ways in which it is likely to impact the health condition. The analysis
as performed in respect to the soil collected from road side has revealed
significant level of findings. It is discussed that the lead concentration in
the soil is a major factor, as deeper the soil; the lead concentration is likely
to be lower. The findings lead to
discussion that the distance of the road side is a major factor affecting the
lead concentration within soil. The experiment as carried out has resulted into
discussion that the level of lead concentration is identified as higher
especially in respect to the road side. This is clarified from the findings
that the distance from the road of 0 km has higher lead concentration in the
soil. This is a major threat to the health performance because lead can account
to significant level of adverse impact on the health performance of people at
large. As a result, necessary precautions are essential from the point of view
of performing the management of health condition in a better manner.
Conclusion
References
LANDRIGAN, P. J. 2002. The worldwide problem of lead in
petrol. Bulletin of the World Health
Organization, 80, 768-768.
REGENTS OF THE
UNIVERSITY OF MINISOTA 2016, accessed on 17 March 2016
http://soiltest.cfans.umn.edu/our-methods/#ENVIRONMENTALLEAD
WU, W. T., TSAI, P.
J., YANG, Y. H., YANG, C. Y., CHENG, K. F. & WU, T. N. 2011. Health impacts
associated with the implementation of a national petrol-lead phase-out program
(PLPOP): evidence from Taiwan between 1981 and 2007. Sci Total Environ, 409,
863-7.
