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Assessing the Heavy Metals Contamination of Surface Dust from Waste Electrical and Electronic Equipment (E-waste) Recycling Site in Accra, Ghana

Authors:
  • Nuclear Regulatory Authority, Ghana

Abstract and Figures

The objective of this was to assess the levels of heavy metals contamination within the vicinity of the Agbogbloshie scrap market. Surface dust samples were collected from various points at the scrap market and its environs. Atomic absorption spectrophotometry preceded by acid digestion was used to evaluate the concentration of the heavy metals in the samples. Heavy metals such as Zn, Cu, Pb and Cd gave concentrations in the range of (10, 575-30, 384 mg/kg), (34-16, 952 mg/kg), (351-5, 105 mg/kg) and (2-72 mg/kg), respectively which were over thousand times more than the levels for which intervention is required. The scrap weighing site, the electronic waste dismantling site and the burning site (where electrical cables are burnt to retrieve metals) recorded the highest levels of heavy metals. Index of geoaccumulation which was employed to determine the level of pollution of the various elements gave the values in the range of 6.7-8.2 for Zinc (Zn), 4.2-8.1 for lead (Pb) and 3.0-7.8 for Cadmium (Cd) indicating extreme pollution from all the sites. This was also confirmed by contamination factor calculations. To assess the extent of pollution of each of the site, degree of contamination was calculated which revealed that the most contaminated site is the Weighing Site (WS) which recorded Cdeg value of 1482.93, followed by Dismantling Site (DS) 1221.6, Burning Site (BS) 1196.9, Road Dust (RD) 1061.9, School Compound (SC) 651.44, Commercial Area (CA) 618.6 and Church Premises (CP) 187.6, respectively. The results also indicate that children living around the scrap market face a very high risk from the ingestion of toxic metals such as Pb and Cd. The weighing site (HI = 205) at the scrap market by far pose the greatest cumulative risk followed by the dismantling site (HI = 130), road dust (HI = 88), burning site (HI = 60), school compound (HI = 52), commercial area (HI = 50) and church premises (HI = 15).
Content may be subject to copyright.
Research Journal of Environmental and Earth Sciences 4(5): 605-611, 2012
ISSN: 2041-0492
© Maxwell Scientific Organization, 2012
Submitted: April 07, 2012 Accepted: April 25, 2012 Published: May 15, 2012
Corresponding Author: Sampson M. Atiemo, National Nuclear Research Institute, Ghana Atomic Energy Commission, P.O. Box
LG 80, Legon 605
Assessing the Heavy Metals Contamination of Surface Dust from Waste Electrical
and Electronic Equipment (E-waste) Recycling Site in Accra, Ghana
Sampson M. Atiemo, Francis G. Ofosu, I.J. Kwame Aboh and H. Kuranchie-Mensah
National Nuclear Research Institute, Ghana Atomic Energy Commission,
P.O. Box LG 80, Legon
Abstract: The objective of this was to assess the levels of heavy metals contamination within the vicinity of
the Agbogbloshie scrap market. Surface dust samples were collected from various points at the scrap market
and its environs. Atomic absorption spectrophotometry preceded by acid digestion was used to evaluate the
concentration of the heavy metals in the samples. Heavy metals such as Zn, Cu, Pb and Cd gave concentrations
in the range of (10, 575-30, 384 mg/kg), (34-16, 952 mg/kg), (351-5, 105 mg/kg) and (2-72 mg/kg), respectively
which were over thousand times more than the levels for which intervention is required. The scrap weighing
site, the electronic waste dismantling site and the burning site (where electrical cables are burnt to retrieve
metals) recorded the highest levels of heavy metals. Index of geoaccumulation which was employed to
determine the level of pollution of the various elements gave the values in the range of 6.7-8.2 for Zinc (Zn),
4.2-8.1 for lead (Pb) and 3.0-7.8 for Cadmium (Cd) indicating extreme pollution from all the sites. This was
also confirmed by contamination factor calculations. To assess the extent of pollution of each of the site, degree
of contamination was calculated which revealed that the most contaminated site is the Weighing Site (WS)
which recorded Cdeg value of 1482.93, followed by Dismantling Site (DS) 1221.6, Burning Site (BS) 1196.9,
Road Dust (RD) 1061.9, School Compound (SC) 651.44, Commercial Area (CA) 618.6 and Church Premises
(CP) 187.6, respectively. The results also indicate that children living around the scrap market face a very high
risk from the ingestion of toxic metals such as Pb and Cd. The weighing site (HI = 205) at the scrap market by
far pose the greatest cumulative risk followed by the dismantling site (HI = 130), road dust (HI = 88), burning
site (HI = 60), school compound (HI = 52), commercial area (HI = 50) and church premises (HI = 15).
Keywords: E-waste, hazard index, index of geoaccumulation, scrap, toxic
INTRODUCTION
The production of electrical and electronic devices is
the fastest-growing sector of the manufacturing industry
in industrialized countries. Due to the demand for newer,
more efficient and effective technology, the life span of
electronic products is becoming shorter and shorter. As a
result of this phenomenon, older and out-dated electronic
equipment are becoming obsolete and are being discarded
in significant amounts worldwide and are illegally
transported to developing countries as electronic waste (e-
waste) (Puckett et al., 2002; Brigden et al., 2005;
Cobbing, 2008). Electronic-waste (e-waste) refers to end-
of-life electronic products including computers, printers,
photocopy machines, television sets, mobile phones and
toys, which are made of sophisticated blends of plastics,
metals, among other materials. The number of electronic
devices used per capita at the global scale is growing at a
rate of about (4%) and will continue to increase as it is
becoming the fastest waste stream world wide (Hilty
et al., 2004, 2008; UNEP, 2005). It has been estimated
that more than 315 million computers became obsolete
between 1997 and 2004 in the United States alone. The
United Nations Environment Programme (UNEP, 2005)
estimate that, 50-80% of the e-waste collected for
recycling in industrialized countries end up in recycling
centers in China, India, Pakistan, Vietnam and the
Philippines (UNEP, 2005). Ghana over the years has
become an e-waste destination and this phenomenon is on
the increase. Every year, 20 to 50 million tonnes of waste
electrical and electronic equipment are generated world-
wide, which pose potential threat to human health and the
environment. Waste Electrical and electronic equipment
can contain many different substances, some of which are
toxic whereas others have a relatively high market value
when extracted. Inadequate disposal and poor recycling
practices in the recovery of precious metals such as gold,
copper and silver contribute to the release of toxic metals
into the environment and which pose health risks to
exposed individuals.
In Ghana, the Agbogbloshie Scrap Market in Accra
is noted for dumping and recovery of materials from e-
Res. J. Environ. Earth. Sci., 4(5): 605-611, 2012
606
wastes. The main electronic wastes processed are obsolete
computers, refrigerators, old tape recorders, scrap
vehicles, used batteries, monitors, television sets and any
used electrical or electronic equipment one can lay hands
on. These used equipments are manually dismantled at
numerous small workshops dotted all over the scrap
market. Certain materials, mainly plastic coated wires and
cables, are then taken to sites on the edge of the market
where they are burned using scattered fires which are set
within this area to enable the retrieval of metals. The
wires and cables are commonly attached to fragments of
other types of materials, including printed circuit boards,
which are also burned (Brigden et al., 2008). This
primitive methods used for e-waste recycling have
contributed to the release of hazardous chemicals
including Polycyclic Aromatic Hydrocarbons (PAHs),
Polybrominated Diphenyls Ethers (PBDEs),
Polychlorinated Dibenzo-p-Dioxins (PCDDs),
Polychlorinated Dibenzofurans (PCDFs) and heavy
metals (e.g., Cr, Cd, Cu and Pb), which have caused
severe pollution to air, dust, soil and water bodies within
the catchment area. The main objective of this study was
to determine the concentration of heavy metals in surface
dust samples collected from various locations of the
Agbogbloshie Scrap Market and its environs and to assess
their levels of contamination. Index of geoaccumulation
and contamination factors have been used to assess the
levels of contamination.
Index of geoaccumulation (Igeo): The index of
geoaccumulation (Igeo) is widely used in the assessment
of contamination by comparing the levels of heavy metal
obtained to background levels originally used with bottom
sediments (Muller, 1969). It can also be applied to the
assessment of road dust contamination (Lu et al., 2009,
2010; Gowd et al., 2010). It is calculated using the
equation:
1geo = log2 (Cn/1.5Bn) (1)
where Cn is the measured concentration of the heavy
metal in road dust, Bn is the geochemical background
concentration of the heavy metal (crustal average) (Taylor
and McLennan, 1985). The constant 1.5 is introduced to
minimize the effect of possible variations in the
background values which may be attributed to lithologic
variations in the sediments (Lu et al., 2009). The
following classification is given for geoaccumulation
index (Huu et al., 2010; Muller, 1969): <0 = practically
unpolluted, 0-1 = unpolluted to moderately polluted, 1-2
= moderately polluted, 2-3 = moderately to strongly
polluted, 3-4 = strongly polluted, 4-5 = strongly to
extremely polluted and >5 = extremely polluted.
Contamination factor and degree of contamination: To
assess the extent of contamination of heavy metals in the
surface soil samples, contamination factor and degree of
contamination has been used (Rastmanesh et al., 2010).
The Cif is the single element index which is determined by
the relation:
(2)
Ccc
f
io
i
n
i
=
1
where; Cif is the contamination factor of the element of
interest; cio-1 is the concentration of the element in the
sample; cin is the background concentration in this study
the continental crustal average has been used (Taylor and
McLennan, 1985).
Cif is defined according to four categories: <1 low
contamination factor; 1-3 moderate contamination factor;
3-6 considerable contamination factor and >6 very high
contamination factor.
The sum of the contamination factors of all the
elements in the sample gives the degree of contamination
as indicated in the equation below:
(3)
CC
f
i
deg
=
Four categories have been defined for the degree of
contamination as follows; <8 (low degree of
contamination); 8-16 (moderate degree of contamination);
16-32 (considerable degree of contamination) and >32
(very high degree of contamination). The threat posed by
heavy metals to human health are caused by a
combination of their chemical characteristics, association
with particulate matter of fine grain sizes, residence time
in the atmosphere and easy transport from emission
sources (Dongarra et al., 2003). Exposure to heavy metals
in surface dust can occur by means of ingestion,
inhalation and dermal contact. In toxicological risk
assessment for non-carcinogenic toxicants, a reference
dose or tolerable daily intake is assumed to be tolerated
by the organism with low or no risk of adverse health
effects (Ferreira-Baptista and De Miguel, 2005).
Populations that are worst affected by exposure to
contaminants are children, pregnant women and the aged.
Children have a greater exposure rate to toxicants than
adults because they breathe more rapidly than adults, can
breathe through their mouth and often engage in a lot of
outdoor activities which lead to high risk of exposure. The
susceptibility of children to the ill health effects of heavy
metals is due to their immatured immune system and
developing organs. Exposure to heavy metals can affect
their respiratory, nervous, endocrine and immune systems
and could increase the risk of cancer in later life.
The daily dose intake ([D(ing)] in mg/kg/day) of
heavy metals from surface dust for infants and children
through ingestion are determined by the relation is given
by:
Res. J. Environ. Earth. Sci., 4(5): 605-611, 2012
607
()
DCmgkg
IngR EF ED
BW AT
ing
()
/**
**
=
10
6
where, C is the concentration of elements in the sample,
IngR ingestion rate (mg/day), EF the exposure frequency
(d/y), ED the exposure duration (years), BW the body
weight (kg) and AT is the averaging time (days). The risk
of exposure to a particular toxicant is the Hazard Quotient
(HQ) which is given by:
HQ DI
RfD
=
where, DI is the dose intake by a given route of exposure
for a particular contaminant RfD is the reference dose for
a particular element through a particular route of
exposure. It is assumed that the toxic risks due to the
heavy metals were additive, therefore the HQ value for
each metal at a location were summed to generate the
Hazard Index (HI) (Leung et al., 2010).
MATERIALS AND METHODS
Dust samples were taken from the Agbogbloshie
scrap market which is widely recognized as an electronic
waste dump site after the publication of the report by
Greenpeace International (Brigden et al., 2008). The
samples were taken from burning sites, dismantling points
and other public places within the vicinity. At the
sampling sites, about 500 g of composite samples were
collected. A soft touch brush was used for sweeping and
plastic dust pan for collecting. A minimum of ten samples
were collected from each point at 6 days intervals from
October 2008 to March 2009. Separate plastic dustpan
and brush were used for sample collection from each site
into pretreated Ziploc polyethene bags to avoid cross
contamination. The samples were carefully labeled and
taken to the laboratories of the National Nuclear Research
Institute of the Ghana Atomic Energy Commission for
elemental analysis. The samples were carefully air-dried
in the laboratory for 1 week and sieved through a 200 :m
mesh nylon sieve to remove debris using Retsch as 200
mechanical shaker for 10 min and 1.5 g of the sample was
weighed into a 100 mL polytetraflouroethylene PTEF
Teflon bombs. Aqua regia solution (1HCl: 2HNO3) was
added followed by 0.25 mL of H2O2. The samples were
digested for 21 min using a milestone microwave
labstation (Ethos 900). After the digestion, the resulting
solution was made up to 20 mL with double distilled H2O.
The concentration of the elements of interest was
determined using Varian AA240FS Atomic Absorption
Spectrophotometer in an acetylene-air flame (Ozaki et al.,
2004; Jaradat and Moman, 1999). The Standard Reference
Material (SRM) IAEA Soil 7 was used for the validation
to verify the accuracy of the results.
RESULTS AND DISCUSSION
The mean concentration of the elements obtained
from SOIL 7 was compared with the certified values by
calculating the ratio of experimental values to certified
reference values. The results gave ratios of 10% or less
indicating the validity of the analytical study.
The result in Table 1 reveal that the concentration of
Pb were in the range 351.1 and 5105.45 mg/kg,
respectively with the highest values recorded at Weighing
Site (WS) (where the dismantled and extracted Pb and
other metals are weighed). During the weighing processes
bare hands were used to collect the samples unto the
weighing scale. This leads to the release of significant
dust hence the risk of inhalation. Other sites within the
vicinity also recorded concentrations which were
thousand times higher than standard set for an
intervention. The site SC is of particular concern because
it is a school compound and Pb is known to cross the
blood brain barrier and exert its toxic effect on children
Table 1: Heavy metal concentrations in dust sampled from the vicinity of the scrape market (mg/kg)
Element Fe Mn Cu Zn Cd Cr Ni Pb
CP Mean 16,743.1 90.7 34.4 10,575.0 2.4 21.6 26.3 351.1
SD 193.8 10.5 5.2 347.2 0.5 2.1 4.2 30.9
DS Mean 17,495.4 294.2 16,318.6 28,957.9 52.1 60.0 101.9 3,162.7
SD 321.2 9.7 531.6 900.6 22.1 5.1 49.5 688.4
WS Mean 17,920.2 293.5 16,951.7 29,720.7 68.5 114.5 191.4 5,105.4
SD 279.4 8.2 641.8 442.7 2.1 19.7 33.6 895.3
BS Mean 16,644.2 145.4 16,627.5 30,384.4 71.6 48.7 95.5 1,321.1
SD 394.0 43.4 622.2 612.1 60.6 17.4 27.5 223.5
CA Mean 16,493.1 189.8 11,589.4 20,847.2 4.4 34.6 28.7 1,149.1
SD 54.9 22.6 3,318.5 1,727.7 1.0 3.9 5.4 218.2
RD Mean 1,7118.0 269.7 31,028.2 22,256.0 5.1 72.4 49.2 1968.4
SD 64.8 70.1 154.2 345.9 0.4 5.2 3.5 100.9
SC Mean 17,543.6 197.4 10,099.1 22,052.3 12.1 105.6 29.9 1,195.2
SD 168.2 35.5 2,614.2 1,216.5 4.7 10.6 4.5 179.3
AT 1,500.0 100.0 300.0 3.0 100 75.0 50.0
IT 2,500.0 200.0 600.0 5.0 300 150.0 100.0
CP: Premises of ICGC headquarters; DS: Dismantling site; WS: Weighing site; BS: Burning Site; CA: Commercial Area; RD: Road dust; AT: Levels
for which attention is required; IT: Levels for which an intervention is required (Lacatusu et al., 2009)
Res. J. Environ. Earth. Sci., 4(5): 605-611, 2012
608
Table 2: Results of index of geoaccumulation (Igeo)
Sample ID Fe Mn Cu Zn Cd Cr Ni Pb
CP -2.3 -4.0 -1.3 6.7 3.0 -2.8 -2.1 4.2
DS -2.3 -2.3 7.6 8.1 7.4 -1.3 -0.2 7.4
WS -2.2 -2.3 7.7 8.1 7.8 -0.4 0.8 8.1
BS -2.3 -3.3 7.7 8.2 7.6 -1.7 -1.0 6.1
CA -2.4 -2.9 7.1 7.6 3.9 -2.1 -2.0 5.9
SC -2.3 -2.9 6.9 7.7 5.2 -0.5 -1.9 6.0
RD -2.3 -2.4 8.6 7.7 4.1 -1.1 -1.2 6.7
Table 3: Contamination factor of sampling sites
Site CP DS WS BS CA SC RD
Fe 0.3 0.3 0.3 0.3 0.3 0.3 0.3
Mn 0.1 0.3 0.3 0.2 0.2 0.2 0.3
Cu 0.6 296.7 308.2 302.3 210.7 183.6 564.1
Zn 151.1 413.7 424.6 434.1 297.8 315.0 317.9
Cd 7.0 255.8 337.5 352.8 17.0 55.3 20.5
Cr 0.2 0.6 1.1 0.5 0.3 1.1 0.7
Ni 0.3 1.3 2.5 1.3 0.8 0.4 0.6
Pb 28.0 252.9 408.4 105.6 91.9 95.5 157.4
such as lowering of IQ and can cause cancer in later life
(Atiemo et al., 2010). The levels of Cd found were in the
range of 2.4 and 71.5 mg/kg, respectively. The toxicity of
Cd and it adverse impact on humans and the environment
cannot be overemphasized. Apart from the samples from
the headquarters of ICGC the rest of the sites had
concentrations which were above the guidance values for
intervention. The dust from the electronic waste burning
site recorded the highest concentration of the Cd this was
followed closely by the weighing point. The school
compound where the sampling was done recorded Cd
concentration of 12.07 mg/kg which is about 240% more
than the value that can trigger an intervention. In a similar
study by Leung et al. (2010) Cd concentration was in the
range of 5 to 10 mg/kg in a school yard, respectively. The
concentrations of Cu and Zn range between 34.4 to
16,951.7 and 10,575.0 to 30,384.45 mg/kg, respectively.
Whereas the highest concentration of Cu (16,951.7
mg/kg) was obtained from the weighing site, that of Zn
(30,384.4 mg/kg) was obtained from the burning site.
These concentrations which are more than one thousand
times the concentrations requiring interventions (Lacatusu
et al., 2009) which reflect the activities that are
undertaken at the sites. Cr, Mn, Fe and Ni also gave very
high concentrations from most of the sites. Ni and Cr
recorded values that exceed both alert and intervention
levels for the samples from the weighing site. For Mn
none of the value exceeded the guidance levels giving
indication of minimal pollution from Mn.
The index of geoaccumulation (Table 2) was
calculated to determine the level of pollution of surface
dust from the sampling site by the various elements. The
results show that Fe, Cr, Ni and Mn indicated no pollution
from all the sites since all the Igeo values for these
elements fell below zero. However, minimal pollution was
observed for at Ni at the Weighing Site (WS) with an Igeo
value of 0.8. Copper showed extremely high pollution at
all the sites with the exception of the Church Premises
(CP). The highest Igeo value for Copper was observed in
road dust. This was a bit surprising because Cu is one of
the metals that are retrieved in the e-waste burning.
However, it is known that Copper forms an integral part
of brake wear and therefore high concentrations have
been found in road dust studies (Atiemo et al., 2012;
Thorpe and Harrison, 2008). Zinc (Zn), lead (Pb) and
cadmium (Cd) showed extreme case of pollution from all
the sites with Igeo values in the range 6.7-8.2, 4.2-8.1 and
3.0-7.8, respectively. The Weighing Site (WS) recorded
the highest Igeo values for Cd and Pb whereas the Burning
Site (BS) recorded the highest concentration for Zn. In all
cases the church premises recorded the lowest Igeo values
but it fell within the range moderate to considerable
pollution.
Results of the calculated contamination factor are
presented in Table 3. It shows that contamination of
surface soil with respect to Fe and Mn was very low at all
the sites. The result also revealed that the Church
Premises (CP), consistently recorded low contamination
factor which is in line with the levels of contamination
observed. Result of the elements Cu and Cd, gave
indication of very high contamination factor at all the sites
with the exception of CP. Zn and Pb recorded very high
levels of contamination at all the sites.
The calculated degree of contamination in the
sampling sites is presented in Fig. 1. The results show that
the Church Premise (CP) has the lowest degree of
contamination. This is because the church premises is
located upwind thereby preventing the thick smoke from
the burning site to the premises. However, there is a
thoroughfare from the Burning Site to the church which is
used by many people going in the direction of the church
hence contaminants are carried to the premises. The site
labeled CA (commercial area) showed extremely high
Res. J. Environ. Earth. Sci., 4(5): 605-611, 2012
609
0
200
400
600
800
1000
1200
1400
1600
CP DS WS BS CA SC RD
Sampling site
D
egree of contain
m
ination
0
50
100
150
200
250
CP DS WS BS CA RD SC
Sampling site
Hazard index (HI)
Fig. 1: Degree of contamination of various sites
Table 4: Hazard Quotient (HQ) for children exposed to heavy metals
from E-waste recycling
Element Fe Mn Cu Zn Cd Cr Ni Pb
CP 0.74 0.03 0.01 0.47 0.06 0.10 0.02 13.37
DS 0.78 0.09 5.44 1.29 1.39 0.27 0.07 120.48
WS 0.80 0.09 5.65 1.32 1.83 0.51 0.13 194.49
BS 0.74 0.04 5.54 1.35 1.91 0.22 0.06 50.33
CA 0.73 0.06 3.86 0.93 0.12 0.15 0.02 43.77
RD 0.76 0.08 10.34 0.99 0.14 0.32 0.03 74.98
SC 0.78 0.06 3.37 0.98 0.32 0.47 0.02 45.53
degree of contamination. As a result of the location of
Banks and other business entities at this site, there are
intense human activities undertaken there. The thick cloud
of smoke from the burning site blows in the direction of
these buildings. Some of the particulates can drop as they
pass over the buildings thereby leading to contaminations.
The School Compound (SC) serves as a place of rest to
some of the people engaged in the scrap business during
the night. This practice is likely to have resulted in the
transport of contaminates from the adjacent scrap market
to the school compound. The countless burning activities
undertaken within the vicinity of the school may also have
contributed to the very high degree of contamination at
the site. Road dust is known to reflect the level of
pollution of a particular site. The contaminants in road
dust may come from exhaust or non exhaust sources
(Atiemo et al., 2010). It is therefore possible that the
combination of vehicular emission and activities of the
scrap dealers, some of which are carried out close to the
road side are responsible for the high degree of
contamination. The Weighing Site (WS), Dismantling Site
(DS) and the Burning Site (BS), respectively recorded the
highest degree of contamination. These are sites with
intense scrap activities within the yard where unscientific
methods are used for dismantling, burning and weighing.
All these activities release high levels of toxic substances
into the environment leading to the exceptionally high
degree of contamination.
Exposure assessment calculations were done based
on the parameters discussed in the introduction and the
results are shown in Table 4. Exposure assessment
involves quantifying the estimated intake of the
contaminant by humans for each exposure pathway
Fig. 2: Cumulative risk of exposure (hazard index) of children
to metals in e-waste
identified. The value obtained, is then used to determine
the risk of non-cancerous or cancerous effect resulting
from exposure to the chemical. In risk assessment studies
the most vulnerable individuals considered are; children,
the aged and pregnant women. In this study, non-
cancerous effect was estimated for children between the
ages of 0-6 years using ingestion as the exposure
pathways. The results show that, HQ values for Pb were
in the range 13.37 to 194.49 with the highest value of
194.49 recorded at the Weighing Site (WS). This value
indicates that an exposed child could consume over
thousand times more than the reference dose for Pb intake
from surface dust at the site. Since Pb is a cumulative
poison and neurotoxic hence prolong exposure can trigger
neurological and developmental disorders in children. For
this reason an HQ value of 45.5 obtained from the School
Compound (SC) should be of serious concern. Cadmium
gave HQ values in the range 0.06 to 1.91 with the highest
HQ values obtained at the Burning Site (BS). This is the
location were plastic coated wires are burnt to retrieve
copper metals. Often children are found loitering around
these areas exposing them to the toxicants. Cadmium is a
very toxic heavy metal which can devastate children’s
immune system within a short period of exposure. Copper
and zinc also recorded varied hazard quotients which are
also major threat to children living in and around the scrap
market.
Fig. 2 shows the cumulative risks of exposure to
surface dust for children living around the area. The
startling results revealed that children living around the
scrap market face strong risk of adverse effect from
exposure to the toxic metals emanating from activities of
the scrape market. The calculated cumulative risks
expressed in terms of Hazard Index (HI) ranged from 15
to 205. These values are over thousand times more
than the safe level of 1.
CONCLUSION
The objective of this study was to assess the
concentration of heavy metals and the levels of
contamination within the vicinity of the Agbogbloshie
Res. J. Environ. Earth. Sci., 4(5): 605-611, 2012
610
scrap market. Surface dust samples were collected from
various points and the vicinity of the scrap market to
assess the levels of contamination within a 500 m radius.
The atomic absorption spectrophotometer was used to
evaluate the concentration of the heavy metals in the
samples.
The results revealed that heavy metal contamination
is pervasive in the area. This may be due to lack of
legislation or the limited legislation regulating the method
used to recover precious metals). It was observed that
heavy metals such as Zn, Cu, Pb and Cd gave
concentrations which were over thousand times more than
the levels for which intervention is required. The scrap
weighing site, the electronic waste dismantling site and
the burning site recorded the highest levels of the heavy
metals. Road dust as well as dust from a nearby school
compound also gave an alarming concentration of these
heavy metals. Index of geoaccumulation which was
employed to determine the level of pollution of the
various elements showed that almost all the sites have
been polluted with respect to Cu, Zn, Pb and Cd. This
result was confirmed by the calculated contamination
factor. To assess the extent of pollution of each of the site,
degree of contamination was calculated which revealed
that the most contaminated site is the Weighing Site
(WS), followed by Dismantling Site (DS), Burning Site
(BS), Road Dust (RD), School Compound (SC),
Commercial Area (CA) and church premises,
respectively. The results also indicate that children
leaving around the scrap market face a very high risk from
the ingestion of toxic metals such as Pb and Cd. The
weighing site (HI = 205) at the scrap market by far pose
the greatest cumulative risk followed by the dismantling
site (HI = 130), road dust (HI = 88), burning site (HI =
60), school compound (HI = 52), commercial area (HI =
50) and church premises (HI = 15).
It is highly recommended that further research study
be carried out into the mode of operation of the scrap
dealers and to recommend environmentally friendly
methods of extracting the desired metals from the waste.
These sites are really contaminated and remedial
measures would be required if the site is to be used for
other purposes in future.
ACKNOWLEDGMENT
The authors would want to acknowledge the
contribution made by Mr. Eric Achaw Kwasi who helped
with the sampling and Mr. Nash O. Bentil for helping
with the analysis.
REFERENCES
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... The second, a case-control study of newborns in Michigan, evaluated relationships between environmental Pb and Cd exposures and abnormal hearing outcomes at birth. Electronic waste workers at Agbogbloshie Market in Accra, Ghana have high occupational exposures to metals [26,27]. The extent to which elevated Pb exposures may play a role in HL outcomes for these workers in Ghana was investigated in a third study using a cross-sectional study design. ...
... However, e-waste also contains metals, including Pb, Cd, and Hg, as well as plastic components, which when burned produce toxic organic compounds [267]. Several studies at Agbogbloshie Market, Ghana's largest e-waste site, have found elevated levels of Cd and Pb in urine of e-waste workers compared with reference sites [26] and elevated concentrations of Pb and Cd in dust at the site and its surroundings [27]. ...
... Given the paucity of studies on this vulnerable occupational group, it is difficult to compare our findings to those of other researchers. Previous literature has examined surface dust samples and determined extremely high hazard quotients at the Agbogbloshie waste recycling site for Pb and Cu, with levels of great concern to child health [27]. Cd and Zn also displayed concerning hazard quotients while Fe, Mn, chromium, and nickel were not of concern [27]. ...
Thesis
Hearing is vital for speech communication and evaluation of the environment. Damage to this sense harms both physical and social health; poor learning outcomes can also arise. Noise is a well-known exposure that can result in hearing loss (HL), but other environmental exposures in combination with noise may also impact HL. Previous studies have suggested that exposures to toxic metals are associated with HL, while essential elements show protective benefits. This dissertation used three studies to explore the relationship between metal exposures and HL, and accounted for exposure mixtures and protective elements. First, a controlled laboratory experiment treated mice with lead (Pb) and cadmium (Cd), both alone and in tandem, in drinking water for twelve weeks. Auditory outcomes were measured following treatment with chemical toxicants in addition to the physical agent, noise. Dosing with Pb and Cd reached relevant occupational exposure levels: mean blood levels were 60.1 μg/dL for Pb and 27.2 μg/L for Cd. Animals displayed mean threshold shifts of 42 dB at 32 kHz following noise exposures of 105 dB. However, threshold shifts were not significantly different from controls after treatment with Pb or Cd alone. Combinations of exposures to Pb and noise, Cd and noise, as well as all three toxicants together did not cause threshold shifts significantly different than noise alone. This adult CBA/CaJ mouse model demonstrated a lack of ototoxicity due to Pb and Cd exposure. Second, a case-control study of newborn infants born between 2003 and 2015 investigated auditory impacts associated with blood levels of Pb and methylmercury (MeHg). Cases with abnormal hearing screenings were matched to controls with normal hearing screenings. Dried blood spots collected after birth were analyzed for MeHg and Pb, in addition to the essential elements calcium, copper, iron, potassium, selenium, and zinc. Conditional logistic regression models of exposure quartiles showed a significant trend (p=0.03) with increasing levels of dried blood MeHg increasing the odds of a hearing screening failure (OR=1.81, 95% CI 1.01-3.24). Models also indicated a significant association with increasing levels of calcium decreasing the odds of hearing screening failure (OR=0.49, 95% CI 0.34-0.70). A significant interaction between selenium and zinc was also noted in logistic regression models. Third, a cross-sectional study in a developing nation investigated Pb and other toxicant metals (arsenic, cadmium, manganese, and MeHg), along with essential elements (copper, iron, selenium, and zinc), and noise exposures in a potentially vulnerable community of electronic waste (e-waste) recycling workers. This study recruited 58 e-waste workers, with an average age of 26, from their worksite in Agbogbloshie, Ghana. Sixty percent of participants were observed to have a noise notch, or elevated hearing thresholds at high frequencies. Potentially harmful levels of noise exposure were observed during both occupational and non-occupational tasks. A metric quantifying the variety of work tasks improved multivariate regression models predicting the degree of hearing impairment at high frequencies. Essential elements were not significantly associated with levels of toxicant metals or HL. However, a significant interaction between levels of zinc and noise was observed. Taken together, these studies do not provide consistent evidence of an ototoxic impact from Pb or Cd exposure; however, MeHg ototoxicity was significant. The three studies also did not find significant evidence of interactions between toxicant metals and noise. Nonetheless, Pb and Cd exposures can damage other tissues relevant to public health.
... Given the paucity of studies on this vulnerable occupational group, it is difficult to compare our findings to those of other researchers. Previous literature has examined surface dust samples and determined extremely high hazard quotients at the Agbogbloshie waste recycling site for Pb and Cu, with levels of great concern to child health [46]. Cd and Zn also displayed concerning hazard quotients while Fe, Mn, chromium, and nickel were not of concern [46]. ...
... Previous literature has examined surface dust samples and determined extremely high hazard quotients at the Agbogbloshie waste recycling site for Pb and Cu, with levels of great concern to child health [46]. Cd and Zn also displayed concerning hazard quotients while Fe, Mn, chromium, and nickel were not of concern [46]. Our study found high blood values of Pb, Cd, and Cu in some participating adults supporting this study's assertion of high levels of health risks due to Pb and Cd, especially concerning where children may be present on site. ...
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Metals, such as lead, may be ototoxic, but this property is not well understood, especially in conjunction with noise. This cross-sectional study investigated hearing, noise, and metal biomarkers in informal electronic waste (e-waste) recycling workers in Accra, Ghana. Workers (N = 58) participated in audiometric testing, a survey, blood collection, and personal noise dosimetry. Sixty percent of participants displayed audiometric notches indicative of noise-induced hearing loss (NIHL). Most workers (86%) reported high noise while working. Daily average noise levels were in the range 74.4–90.0 dBA. Linear regression models indicated participants who lived at Agbogbloshie Market for longer periods were significantly associated with worse hearing thresholds at 4 and 6 kHz. The models did not identify blood levels of lead, mercury, or cadmium as significant predictors of worse hearing thresholds or larger noise notches, but increased levels of selenium were significantly associated with better hearing at 6 kHz. Models of thresholds at 4 and 6 kHz were improved by including an interaction term between the maximum noise exposure and the level of zinc in whole blood, suggesting that zinc may protect hearing at lower noise levels, but not at higher levels. Further study of the relationships between elements, noise, and NIHL is needed.
... Electronic and electrical equipment (EEE) contain toxic materials, which are dangerous to the environment; thus, requiring special and safe handling practices Sthiannopkao and Wong 2012;Bansode et al. 2015). Electronic and electrical waste (e-waste) products have both valuable and hazardous components (Chi et al. 2011;Atiemo et al. 2011). According to Bertram et al. (2002), e-waste is one of the largest sources of heavy metals in the municipal waste stream and has become a major problem in developing countries, which needs special attention. ...
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This paper examines the awareness and attitudes of electronic waste (e-waste) workers about the environmental risks of e-waste activities in two informal recycling sites in Ghana: Agbogbloshie (Accra) and Dagomba Line (Kumasi). Using semi-structured interviews with 255 e-waste workers and relevant agencies, the results showed that most workers (73%) know about the environmental risks. The com-monest environmental risks reported were air pollution by fumes from open burning and dumping of unwanted e-waste items in the open environment. Awareness of the risks was influenced by site location, age, educational status and length of years involved in the activity. The study found the existence of some environment-friendly alternatives to minimise risks and exposure at both sites, notably, a granulator at Agbogbloshie and a 20-m metallic emission stack at Dagomba Line. The workers, however, did not adopt the alternatives due to their inefficiency. The study concludes that accommodating informal e-waste recycling activities in the cities, which are already part of the urban fabric, requires efforts to address all the challenges associated with the reluctance of workers to adopt some of the identified environment-friendly practices. There should also be continuous training on safer practices and communication on associated risks.
... The toxic and cancerous pollutants released into the environment during improper treatment of e-waste at end-oflife (Fig. 2), include heavy metals such as lead, cadmium, and mercury, as well as dioxins, furans, and polycyclic aromatic hydrocarbons [12]. Within Africa, close to e-waste processing sites, toxic elements, persistent organic pollutants (POPs), and heavy metals have been observed in elevated levels in dust, soils [30][31][32][33] and vegetation, including edible plants [34,35]. Further environmental effects have been observed because of higher metal and rare earth element (REEs) [36] concentrations in downstream aquatic and marine environments, causing adverse marine consequences including smaller, sicker, and sparser fish stocks [37,38]. ...
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E-waste is the world's fastest growing and most valuable domestic waste stream. The increasing production of e-waste is driving elevated levels of export from developed to developing countries. Although countries worldwide are actively recognising the issues around e-waste and introducing policies, legislation or regulations governing e-waste, a large fraction of e-waste, goes undocumented at its end-of-life. Much of the global e-waste is accumulating in open dumpsites in several African countries. Using available data, we calculate the total e-waste in Africa (locally produced plus imported e-waste) for 2019 to be between 5.8 and 3.4 metric tonnes (Mt). This is believed to be an underestimate, large data gaps exist, hindering more precise estimates. The data is further complicated by, sometimes intentional, differences in labelling and reporting between formal and intermittent informal importers. Based on the available data, the main African recipients of e-waste are Nigeria, Ghana, and Tanzania, with Kenya, Senegal and Egypt featuring as countries of concern. The lack of proper waste management in the recipient developing countries, leads to environmental contamination and human exposure. A coordinated, regional and global, approach is needed in tackling e-waste. Regulatory frameworks, together with monitoring and compliance mechanisms need to be developed, financed, and enforced.
... Rights reserved. In Ghana, Atiemo et al. (2012) studied the concentration of heavy metals in surface dust in the vicinity of e-waste recycling site at Agbogbloshie, Ghana. Surface dust samples were collected from weighting site, dismantling site, burning site and other public sites (church premises, road dust, school compound, commercial area) and were analyzed using AAS to find out concentration of heavy metals. ...
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Decrease in life span of electronic devices and consumer’s urge to use advanced technology leads to obsolescence of such devices, resulting in electronic waste generation. The technology for e-waste components recycling has made great progress. However, due to growing environmental concern, there is a need to find alternatives for conventional e-waste recycling methods to achieve a safer environment. Rapid surge in e-waste generation is a matter of concern due to elevated levels of heavy metals and persistent organic pollutants (POPs) in air, soil and water caused by informal recycling practices. Moreover, recycling of printed circuit board (PCB), a major part of electronic waste, in order to recover metals, results in release of waste acid leach water, if untreated, which contain heavy metals like Pb, Cr, Ni, etc. This has given rise to the development of several remediation techniques for soil- and water-like phytoremediation, soil washing, bioremediation, and application of nanoparticles, which have been compared and reviewed in this paper along with their limitations for application at larger scale for real-contaminated soil. This review focuses on the existing remediation techniques and their limitations to decrease environmental hazards caused by the release of various pollutants through e-waste recycling. Graphic abstract
... The digestion process carried out in an open vessel under reflux conditions, or in a closed vessel assisted by microwave radiation, involving the use of HNO 3 , HCl, HBF 4 , HF H 2 O 2, and their mixtures, and are described in many publications [19,[34][35][36][37][38]. The efficiency of a digestion protocol for solid waste is dependent on the waste matrix, the chemical form of the metals in the waste matrix, and the acids used in the digestion process [33]. ...
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The article draws attention to the problem of the presence of metals: germanium (Ge), tellurium (Te), thallium (Tl), and others (Cd, Ba, Co, Mn, Cr, Cu, Ni, Pb, Sr, and Zn) in selected waste of electrical and electronic equipment (WEEE). As a result of the growing demand for new technologies, the global consumption of TECs has also been increasing. Thus, the amount of metals in circulation, of which the impacts on the environment have not yet been fully understood, is constantly increasing. Due to the low content of these metals in WEEE, they are usually ignored during e-waste analyses. The main aim of this study was to determine the distribution of Ge, Te, and Tl (and other elements) in ground sieve fractions (1.0, 0.5, 0.2, and 0.1 mm) of selected electronic components (solar lamps, solar cell, LED TV screens, LCD screens, photoresistors, photodiodes, phototransistors) and to determine the possible tendency of the concentrations of these metals in fractions. This problem is particularly important because WEEE recycling processes (crushing, grinding, and even collection and transport operations) can lead to dispersion and migration of TCE pollutants into the environment. The quantitative composition of e-waste was identified and confirmed by ICP-MS, ICP-OES and SEM-EDS, and XRD analyses. It was found that Ge, Te, and Tl are concentrated in the finest fractions of ground e-waste, together with Cd and Cr, which may favor the migration of these pollutants in the form of dust during storage and processing of e-waste.
... Heavy metal contamination in soil and water is a widely recognized global problem because of its high toxicity to biotic communities, bioaccumulation and biomagnification in food chains (Bang et al., 2015;Batvari et al. 2008;Kamala-Kannan et al., 2008;Batvari et al., 2012) and unlike organic substances, heavy metals are essentially nonbiodegradable and therefore accumulate in the environment (Ali, Khan and Sajad, 2013). As mentioned by Khan et al., (2010) Heavy metal contamination of the aquatic environment is increasingly becoming common in many developing countries, where there has been linked to several anthropogenic processes including artisanal gold mining, (Donkor et al., 2005;Gbogbo, 2017) electronic waste processing (Caravanos, et al., 2011;Atiemo, Ofosu, Aboh & Kuranchie, 2012) industrial processes (Armah, Obiri, Yawson & Pappoe, 2010) domestic sewage discharges (Flanko et al., n.d.) and agricultural activities (Gbogbo, 2017). ...
Research
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In order to make the environment healthier for human beings, contaminated water bodies and land need to be cleansed to make them free from heavy metals and trace elements. This study aimed to determine the heavy metal phytoremediation potential of Brassica chinesis (pechay). This study used a completely randomized experimental research design and was conducted at PengueRuyu Tuguegarao City from June 21, 2017 to October 6, 2017. The plant was cultivated in a hydroponics system. Three hydroponics solutions were prepared namely the control, hydroponics solution spiked with cadmium and the hydroponics solution spiked with lead. The plants were grown in these hydroponics solution for ninety days. After which, the concentration of the heavy metals in the hydroponics solution, roots and shoot system of the plant was determined with the use of Flame Atomic Absorption Spectrophotometer at the Department of Science and Technology [DOST]Regional Standards and Testing Laboratory Regional Office 2 in Tuguegarao City, Cagayan. The phytoremediation potential of Brassica chinesis were described in terms of the bioconcentration factor (BCF) and translocation factor (TF).Results of this study revealed that Brassica chinesis is a potential metal excluder for lead where most of the heavy metals are deposited at the roots of the plant. Moreover, it has also the phytoremediation potential as shown by its high value of BCF and low value of TF. Lastly, it was found out that the plant is a potential phytoremediator both for cadmium and lead.
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The present study investigates the concentration of heavy metals in the soils of Moradabad, famous for manufacturing brassware, in the vicinity of the abandoned sites of e-waste burning and industrial waste. Government of India has strengthened enforcement to impede such activity, however, heavy metal remains in the abandoned e-waste burning and industrial waste sites can still pose an ecological risk. Results indicate that the surface soil of the e-waste burning and acid leaching sites was still heavily contaminated with the heavy metals likes Pb, Cd, Cr, Zn, Ni, Cu and Fe originating from printed circuit board burning and recycling. Industrial waste has also affected the nearby areas, which have created potential threat to the environment. Samples were collected from the various contaminated sites, after the digestion process they were analysed by ICP-AAS. The excedance of metal contamination imposed negative impact to the environment and human health. Therefore, immediate remediation of the contaminated soil is necessary to prevent the dissemination of heavy metals and potential ecological disaster.
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Street dust samples were collected from industrial and commercial cities (Jamshedpur and Ranchi during monsoon and post-monsoon seasons) for detecting the levels of Cr, Cd, Cu, Ni, Pb, Zn, As, Co, Al, and Mn. The industrial city recorded higher metal concentrations compared to commercial. Similar trend of pseudo-total metal concentrations was observed in both the seasons at industrial city (Al > Mn > Zn > Cr > Pb > Cu > Ni > Cd) and only monsoon season at commercial city (Al > Mn > Zn > Cu > Cr > Pb > Ni > Cd). Zn > Cd was the most bioaccessible metal throughout the cities (monsoon and post-monsoon). The geochemical parameters (Igeo, EF, CF) were highest for Cd and lowest for Ni (both cities for the two seasons). Pollution Load Indices (PLI zone) were highest during the post-monsoon season in the industrial city. The highest carcinogenic risk was posed by Cr ranging from 1.87E-05 to 4.80E-05, in both the cities through ingestion and inhalation pathways. Children were found at higher risks, while the bioaccessible fractions posed neither carcinogenic nor non-carcinogenic threats to the population. Principal component analysis and correlation analysis indicated the influence of vehicular and industrial emissions, especially steel industry and coal-based thermal power plants as the major source of metals in street-dust. The outcomes of this work will be useful in providing baseline information of pollution along with their consequent environmental and human health risks of Jharkhand state. Graphical abstract
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Soil contamination at electronic waste (e‐waste) recycling sites is pervasive, though many locations have yet to be studied. While such contamination can present risks to soil organisms, little is known on the topics, especially in native species. The objective of this study was to increase understanding of soil contamination by heavy metals at e‐waste recycling sites, and the amount that these metals bioaccumulate in Alma nilotica, a tropical earthworm species. Soil samples were collected from 8 informal e‐waste recycling sites and 2 reference sites in Douala, Cameroon and analyzed for metals content via Inductively Coupled Plasma‐Mass Spectrometry (ICP‐MS). The resulting concentrations could be rank ordered as Cu > Pb > Zn > Hg > Ni > As > Cd > Co > Cr. The concentrations were significantly higher in e‐waste sites compared to reference sites. Based on contamination factors the soils ranged from ‘moderate’ to ‘very high’. Based on the modified degree of contamination indice all soils were classified as ‘ultra‐high’; and the order of metal ecological risk index was Zn > Pb > Ni > Hg > Cu > Cr > Co > Cd > As. There was a positive correlation between soil metal concentrations and earthworm accumulation though metals with higher soil concentrations tended to have lower bioaccumulation factors (BAFs). Only Hg and Co had BAFs >1. These results document that e‐waste sites in Douala are contaminated with metals, and that native earthworm species can bioaccumulate relatively high amounts. With e‐waste recycling growing worldwide, there is a need for more data especially from understudied locations and native species that may be impacted. This article is protected by copyright. All rights reserved.
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Copper smelting and toxic emissions in Sarcheshmeh Copper Complex have resulted in soil pollution especially in the vicinity of the smelting plant. Calculated geoaccumulation index, contamination factor (C f), and contamination degree (C deg) indicate surface soil enrichment in potentially toxic metals (As, Cu, Pb, Zn, Mo, and Cd). The results also indicate that most contaminated areas are located in the prevailing wind directions (N and NE). However, continuous copper smelting can result in extensive pollution in the study area. This is especially alarming for adjacent townships. Since, the sampled sites are also used as grazing land, the soils are likely to become phytotoxic and provide a potential pathway for the toxic elements to enter the food chain. C f based on distance and direction give more reasonable results; that is, the decrease of contamination degree with distance. This is in agreement with I geo and also statistical analysis, which show a decreasing trend of metal loadings of soil with distance from the smelter. Statistical analysis reaffirms the polluting role of the smelting plant.
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Abstract: The aim of this paper is to establish the abundance of heavy metals in the soils affected by the past Rosia Montana gold and silver ore mining, and in currently unaffected soils that will be impacted by the proposed Rosia Montana project that foresees the expansion of the ore exploitation and a new processing facility. The soil cover of the Rosia Montana area consists of five soil types: Eutricambosols, Districambosols, Regosols, Lithosols, and Aluviosols. The first two types are prevalent; they cover 73.83% of the total researched surface (1,646 ha). In the soils from the areas where mining activities have been carried out, the total content of the heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn) vary from the region’s pedogeochemical background level up to the alert threshold for heavy metals pollution set down in the Order of the Ministry of Waters, Forests, and Environment Protection no. 756/1997. The analysis of soils from and surrounding the existing ore processing facilities shows that the heavy metals contents in few cases is above the intervention threshold, for copper, lead and zinc. The soils generally have low heavy metals contents and the values are at the region’s pedogeochemical background level. The barren rocks, generally, have low heavy metals contents, close to the clark values. Taking all this into account, as well as the technology that the Canadian company intends to apply, there is a low probability that a significant heavy metals pollution of the soils left un-stripped would occur due to the proposed project.
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The distribution, controlling geochemical factors and contamination status of heavy metals in estuarine sediments near Cua Ong Habor, Ha Long Bay (Vietnam) were investigated. 36 surface sediment samples were collected and analyzed for major elements (Al, Ca, Fe, K, Mg, S), heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn), organic matter, loss on ignition (LOI), grain size composition and pH. Spatial distribution patterns of heavy metals as well as their controlling factors were elucidated based on geochemical mapping and statistical methods such as the Pearson Product-Moment linear correlation and Factor Analysis. The results illustrated that the distribution patterns of As, Cd, Cr, Cu, Ni, Pb and Zn are mainly controlled by organic matter and clay minerals and determined by the distribution of the fine-grained fraction (Φ < 63 µm) in the sediments. In contrast, Fe and Mn compounds seem to exert some control on the distribution of Co. Carbonates partly control the distribution of Mn, but are not important with respect to the other studied heavy metals. The contamination status by heavy metals was assessed based on comparison with Canadian, Wisconsin-United States and Flemish numerical Sediment Quality Guidelines, and calculation of Geo-accumulation Index (I geo) and Enrichment Factor (EF). The results indicated that natural processes such as weathering and erosion of bedrock are the main supply sources of heavy metals in sediments near Cua Ong Harbor. Among the studied heavy metals, only As is of concern whereas Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn seem to reflect their background concentrations in sediments of Ha Long Bay.
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The vision of Pervasive Computing is built on the assumption that computers will become part of everyday objects, augmenting them with information services and enhanced functionality. This article reports on the approach we have used to assess potential side effects of this development on human health and the environment, and the major risks we identified. Social risks such as the risk of conflicts between users and non-users of the technology were also included because of their potential indirect adverse health effects. Assessing a technological vision before it has materi-alized makes it necessary to deal with two types of uncertainty: first, the uncertainty of how fast and to what extent the technology will be taken up and how it will be used; second, the uncertainty of causal models connecting technology-related causes with potential health or environmental effects. Due to these uncertainties, quantitative methods to evaluate expected risks are inadequate. Instead, we developed a "risk filter" that makes it possible to rank risks according to a set of qualitative criteria based on the Precautionary Principle. As the overall result, it turned out that Perva-sive Computing bears potential risks to health, society, and/or the environment in the following fields: Non-ionizing radiation, stress imposed on the user, restriction of consumers' and patients' freedom of choice, threats to ecological sustainability, and dissipation of responsibility in computer-controlled environments.
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Street dust samples were collected from Tema Motorway (near Ashiaman overhead) and Tetteh Quarshie interchange in Accra. The samples were segregated into two groups of grain sizes be-tween 100 um - 250 um and the other being less than 100 um. Energy dispersive X-ray flores-cence technique was used to determine their elemental compositions. In all twenty (20) elements were identified: K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr and Pb. The results show significant concentrations levels of K, Ca, Ti Pb, Zn, Cu, Mn, Fe, Rb, Sr, Y, Zr and Cr in all the samples. Enrichment factors determined for the elements show high enrich-ment of V, Zn, Cu, Zr, Cr, Br and Pb from the sample sites. There was no indication of signifi-cant anthropogenic contribution of manganese (Mn) which gave average enrichment factor val-ues of 0.60 and 0.78 in the road dust at the Tema motorway and Tetteh Quarshie Interchange respectively. Risk assessment of selected heavy metal contaminants from both sites indicate that Pb gave Hazard Index (HI) values of 0.56 and 0.62 which falls below the safe level of one (1). It was also observed that ingestion which gave HI values of 2.1 and 2.3 was the highest risk of ex-posure pathway. Tetteh Quarshie Interchange gave the highest cumulative risk of exposure.
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In order to assess the effect of "overuse" in natural parks, roadside soil and dusts were collected from Kamikochi, Chubu Sangaku National Park (Kamikochi) to Matsumoto City, Nagano Prefecture, Japan. Also, the concentrations of As, Sb, Hg and 5 other heavy metals (Ni, Cu, Zn, Cd, Pb) were measured. The higher concentrations of these 8 elements were observed at Kamikochi Bus Terminal, Kama Tunnel, Matsumoto Interchange and the east exit of Matsumoto Station. These 4 sites are strongly affected by the presence of automobiles, which is believed to be responsible for the higher concentrations. Moreover, the concentrations were increased in the summer, probably due to the corresponding traffic volume, related to the tourist season. Many significant positive correlations among the 8 element concentrations were found as well. The information above suggested that As, Sb and Hg distributions are closely related to automobiles, which play an important role in transportation of visitors, meaning the anthropogenic pollution.
Article
Environmental studies have revealed significant contributions of vehicular exhaust emissions to high pollution levels in urban dwellings. The levels and sources of heavy metal contaminations of some major roads in Accra have been investigated in this work. Street dust samples collected from four major roads in Accra (Mallam Junction-Weija road, John Teye-Pokuase road, Tema Motorway and Tetteh Quarshie Interchange in Accra) were analysed for their elemental concentrations using energy-dispersive X-ray fluorescence. Twenty elements were identified: K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr and Pb. Significant concentration levels were obtained for K, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Br, Rb, Sr, Y, Zr and Pb in all the samples and were used for the source identification. Enrichment factors and principal component analysis were used to verify the anthropogenic contribution to road dust. Results obtained for the enrichment factors showed moderate enrichment for V, Cr and Cu, while Zn, Br, Zr and Pb were significantly enriched. Principal component analysis identified four sources and their contributions to the elemental contents in the road dust. Natural crust, brake wear, tyre wear and vehicle exhaust emission were the four sources identified. The contribution of vehicular non-exhaust emissions to heavy metal contamination in the road dust was found to be greater than that of exhaust emissions. Copyright © 2012 John Wiley & Sons, Ltd.
Article
Copper, lead, cadmium, and zinc levels were analyzed by atomic absorption spectrophotometry in surface soil, plants, and air samples taken from both sides of the major highway connecting Amman with the southern parts of Jordan. Elevated levels of the studied elements were found in both soil and plants on the east side and on the west side of the road compared with the background values. The higher levels of heavy metals east of the road were due to the westerly prevailing wind at the sampling sites. The comtamination decreased exponentially with distance from the edge of the road and dropped to the background level at about 60 m. In soil samples, the average concentrations, 1.5 m east of the highway, were 29.7, 0.75, 188.8 and 121.7 g/g for Cu, Cd, Pb, and Zn, respectively. The levels of these elements in plants 3 m east of the highway were 31.3, 7.3, and 98.7 g/g for Cu, Pb, and Zn, respectively, whereas for air they were 0.40, 0.94, and 0.26 g/m 3 . The values of the heavy metals suggest that automobiles are a major source of these metals in the roadside environment and also these values were compared with results found by other investigators in various countries worldwide. Finally, the roadside soil and plants had signicantly high contents of heavy metals and their levels increased with increasing trac densities and furthermore, they reached elevated levels in urban areas.
Book
This book describes the composition of the present upper crust, and deals with possible compositions for the total crust and the inferred composition of the lower crust. The question of the uniformity of crustal composition throughout geological time is discussed. It describes the Archean crust and models for crustal evolution in Archean and Post-Archean time. The rate of growth of the crust through time is assessed, and the effects of the extraction of the crust on mantle compositions. The question of early pre-geological crusts on the Earth is discussed and comparisons are given with crusts on the Moon, Mercury, Mars, Venus and the Galilean Satellites.