ABSTRACT
Investigations were carried out for heavy metals composition of ambient air using a special instrument designed for this purpose. The lack of portable air sampler is a major obstacle to air pollution studies in Nigeria of recent. As a remedy to this, a simplified air sampler was designed and fabricated at the Water Resources and Environmental Engineering Department. Varied designs of this sampler were constructed and deployed for assessing the air quality of some selected heavy metals in some commercial areas in Kaduna metropolis such as Chechenia Market, Ahmadu Bello Way, Old and New Panteka. The instrument was mounted in strategic locations free from interference by humans and other natural factors. In accordance with standard methods, the trapped samples were washed in de-ionized water, diluted and digested and analyzed by Atomic Absorption Spectrometer (AAS) for the heavy metals zinc (Zn) lead (Pb) and iron (Fe). From the results Chechenia Market recorded mean values of Zn=1.55, Pb=0.00 and Fe=1.65 mg/l, Old Panteka recorded mean values of Zn= 0.13, Pb=0.00, Fe=4.29 mg/l and New Panteka recorded mean values of Zn=3.05, Pb=0.02, Fe=2.37 mg/l. These results were compared with national and international standards of National Environmental Standards and Regulations Enforcement Agency (NESREA) (2009) and the World Health Organization (WHO) (2011).Pb showed low mean values in the rainy season while the mean values obtained in the dry season were high. Zn and Fe maintained a fairly constant mean value though the values for Fe were high above recommended values of NESREA (2009)/WHO (2011).The results showed that Zn and Fe were above the permissible limits while Pb was within the permissible limit.The presence of these heavy metals in these areas maybe from numerous on-going human activities such as smelting of metals, vehicle exhaust, wearing of brake pads, tire abrasion, road dust and burning of refuse, among others. This investigation has highlighted that these heavy metals fractions exist in the air around these parts of Kaduna metropolis and they could be detrimental to human health. Further studies are recommended to determine the risks posed by these fractions and develop technological and management options for their reduction. Phasing out any remaining use of heavy metal additives should be encouraged.
CHAPTER ONE
INTRODUCTION
Pollutants can be in the form of solid particles, liquid droplets, or gases, in addition, they may be natural or man-made (Anderson, 2005). It can be air, water or land and can result from mining, automobile exhaust, agricultural and industrial activities among others. Heavy metals were since classified among major causes (Galadima et al., 2011). Of the important pollutants, heavy metals cause serious harmful effects on the environment. Standard limits andinternational guidelines specify maximum level for various pollutants in air samples; however no restrictions have yet been set in Nigerian towns and cities. Major towns and cities have often suffered from smoke emanating from residential building, refused dumps and bio-mass incineration. Residual oil combustion and automobile exhaust which are all as a result of human activities results in release of toxic materials (e.g. heavy metals) into the atmosphere (Okou and Nchiokwere, 2005).
Suspended particulate matter is one of the most important constituents of atmospheric pollution. Consequently, exposure to airborne particles is a common event. Suspended particulate matter is a complex mixture of elemental and organic carbon, ammonium, nitrates, sulphates, mineral dust, trace elements and water droplet. Among all air pollutants, particulate matter (PM) especially respirable PM which can be inhaled into the human respiratory system (Wallenborn et al., 2009) is related to the most serious health effects including pulmonary and cardiovascular illnesses (Harrison, 1999). The chemical characteristics of atmospheric particulate are important for both particle toxicity and its role in climate change (Hueglin et al, 2005, IPCC, 2001; Salve et al, 2007).
Suspended particulate matter is a mixture of organic and inorganic substances characterized by their physical attributes, which influence their transport and deposition, and their chemical composition which influences their effect on health. Heavy metals are chemical elements with a
specific gravity which is at least 5 times the specific gravity of water (which is 1 at 4°C (39°F). Known toxic metallic elements with a specific gravity that is 5 or more times that of water are Arsenic – 5.7, - Cadmium – 8.65 Iron – 7.9, Lead - 11.34 and Mercury 13.546, (WBG, 1998). This classification also includes some heavy metals in group III to V in the periodic table. Heavy metals occur as natural constituents of the earth crust, and are persistent environmental contaminants since they cannot be degraded or destroyed (Galadima and Garba, 2012). Although these elements are lacking in abundance they are not lacking in significance (Chen and Chen, 2001). Mercury and lead for example are commonly used in technology but are so toxic that minute quantities can destroy life. In Nigeria numerous studies indicated that industrial activities releaseheavy metals either as solids, gas or liquids in the form of waste water allowed to drain into water bodies and water ways.
1.1 HEAVY METALS IN NIGERIAN ENVIRONMENT
Heavy metals are generally introduced into the environment through water, air and soil (Ayodele and Abubakar, 2001, Ibeto and Okoye, 2010). However the degrees of concentration depend on the type of heavy metals and activities taken place in a particular area. Nowadays in Nigeria several ways have been identified through which specific heavy metal can be transmitted into living species.
Heavy metals are released from various sources such as municipal wastewater sludge, urban composts, road traffics, atmospheric deposits and agrochemicals such as fertilizers, pesticides, fungicides and so on. Within the terrestrial ecosystem, soil plays a major role in element cycling and accumulates heavy metals in concentration orders of magnitude higher than in water and air (Udensi, 2010). The impact of heavy metals on the environment is a concern to the government
regulatory agencies and the public. Deposition of air pollutants is captured by the plant canopy and accumulated in or on the leaves. As the accumulation is roughly a function of the deposited amount of pollutants, the exposure time and the effects of climatic factors are of prime importance.
Metals that are from airborne sources are usually discharged as particulates consist on the gas stream. Some metals like cadmium ( Cd), Arsenic ( As) and lead ( Pb) can similarly volatilize by high temperature activities. These metals will change to oxides because of smaller suspended particulate matter until the pollution levels are high (Smith et al. 1995). Emissions from chimney may be circulated over an extensive area by natural air flow still dry and wet precipitation actions thereby eliminate them from the gas tributary and into the environment.
Heavy metal is a general term which applies to the group of metals and metalloids with an atomic density greaterthan 4g/cm3 (Ademoriti, 1996). Most of the heavy metals accumulate in the biological environment in different ways, via the nutrient chain. Increasing heavy metal accumulation at critical levels in living organisms, some contaminated environment may have morbidity and mortality effects. Commercial and industrial garbage may contain toxic materials such as lead, mercury, cadmium, manganese from batteries, insect sprays, nails, polish cleaners, plastics or polyvinyl chlorides, bottles and other assorted product which have unknown physiological effect when ingested (Dosumu et al, 2003). The major effect of lead may include anemia, effects on the nervous system, reproductive system, cardiovascular, and hepatic, renal endocrinal and gastrointestinal systems. Lead is toxic even at low concentration and has no function in biochemical process (Sobolv et al, 2008). Once liberated into the environment through the air, drinking water, food, or countless varieties of man-made chemicals and products,
heavy metals are taken into the body via inhalation, ingestion and skin absorption. If heavy metals enter and accumulate in body tissues faster than the body‟s detoxification pathways can dispose of, then a gradual build-up of these toxins occurs. High concentration exposure is not a necessity to produce a state of toxicity in the body, as heavy metal accumulation occurs in body tissues gradually and, over time, can reach toxic concentration levels, much beyond the permissible limits (Suruchi et al, 2012). Lead and cadmium are among the most abundant heavy metals and are particularly toxic. The excessive amount of these metals in food is associated with etiology of a number of diseases, especially with cardiovascular, kidney, nervous as well as bone diseases (Sanchez-Castillo et al., 1998; Steenland and Boffetta, 2000). Lead is well known for its toxicity and adverse effects on human health. Absorption of ingested lead may constitute a serious risk to public health. Some chronic effects of lead poisoning are colic, constipation and anemia (Bolger et al. 2000).
1.2 SCOPE OF THE STUDY
The scope of the study was developing a model that was used to collect heavy metals in suspended particulate matter in Ahmadu Bello Way, Old Panteka and New Panteka.
1.3 LIMITATION OF THE STUDY
Limitations of the study include:
1. Difficulties in situating the model
2. Sampling with the model was also difficult because of placing the sampler; people were also scared due to the security challenge in the country.
3. There was also the problem of power due to difficulty in changing the battery because the sampler discharges its battery often.
1.4 STATEMENT OF RESEARCH PROBLEM
Like in most developing nations the issues of maintaining good atmosphere are much and these importance include; lack of equipment and tools, inadequate expertise, lack of infrastructure and weak policy frame work. This and many other factors has been the obstacle to achieving the much desired goals towards preserving the quality of the air and safeguarding the health of the public in the region. Hence the need to provide a local air sampler in order to achieve one of this goals.
1.5 JUSTIFICATION.
The fabrication of a local air sampler will help in address some of the factors that will help in achieving air quality and environmental health in developing nations, cause assessing pollutants in different components of the ecosystem has become an important task in preventing risk to wildlife and public health.
1.6 AIM OF THE STUDY
The aim of this work is to design an air sampler for air quality and assess the heavy metal concentration of ambient air of some selected commercial Areas in Kaduna Metropolis.
1.7 OBJECTIVES
i. To design and construct a Model Air sampler.
ii. To determine the atmospheric levels of heavy metals in the selected areas.
iii. To clarify the status of the area‟s air quality.
iv. To determine the probable sources of the pollution.
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Item Type: Project Material | Size: 103 pages | Chapters: 1-5
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