Environmental Impact Assessment of Dumpsites in Zaria Metropolis, Kaduna State, Nigeria

Environmental Impact Assessment of Dumpsites in Zaria Metropolis, Kaduna State, Nigeria

Chapter One

Aim and Objectives

This investigation aimed to assess the dynamics of dust particulates –soil leachates – water – vertebrates – human pollution with a special preference for heavy metals (Hg, Cu, Cd, Zn, and Pb), and some gaseous pollutants (SO₂, NO_2, H₂S, NH₃, flammable gas (Fl) and CO) from dumpsites of Zaria Metropolis, Kaduna State, Nigeria in dry and wet seasons. This aim was designed to be achieved through the following objectives:

To Assess quality of the groundwater near the dumpsites in comparison with the standard
To characterize the refuse wastes, determine physicochemical parameters and levels of metals in the soils and leachates using sequential extraction
assess the quality of the air around the dumpsites and compare it/them to standard
To determine the concentrations of the heavy metals in the tissues and organs of chickens fed with the refuse
To determine the concentrations of the afore mentioned heavy metals in blood, nails, hair and urine samples of people living at the vicinity of dumpsites across the
To develop a bismuth electrode (BiEs) and ascertain its workablity compared to other analytical methods for the determination of heavy metals in water

CHAPTER TWO

LITERATURE REVIEW

Health Implications of Open Waste Disposal

Improper disposal of solid waste disposal is one of the main causes of environmental pollution and degradation in many cities, especially in developing countries (UNEP, 2005). Many of these cities lack solid waste regulations and proper disposal facilities including those for harmful waste which may be infectious, toxic or even radioactive (UNEP, 2005).

Municipal waste dumpsites are designated places set aside for waste disposal. Depending on a city‘s level of waste management, such waste may be dumped in an uncontrolled manner, segregated for recycling purposes or simply burnt. Poor waste management poses a great challenge to the well-being of city residents particularly those living adjacent to them as they pollute water, food sources, land, air and vegetation (UNEP, 2005). The poor handling and disposal of waste thus leads to environmental degradation, destruction of the ecosystem and poses great risks to public health (UNEP, 2005), Fig. 4.1 summarizes the major threats of dumpsites to public health.

Heavy Metals The term heavy metals refers to any metallic element that has a relatively high toxicity or poisonous effect even at low concentration (Lenntech, 2004; Duruibe et al., 2007). It is a general collective term which applies to the group of metals and metalloids with atomic density greater than 4g/cm³ or five times or greater than water (Nriagu, 1989). However, being a heavy metal has nothing to do with density but concerns with chemical properties. Heavy metals include lead, cadmium, zinc, mercury, arsenic, silver, chromium, copper, iron and platinum group elements. Environment is defined as the totality of circumstances surrounding organisms especially the combination of external physical conditions that affect and influence the growth, development and survival of organisms (Farlex, 2005). It consists of the flora, fauna and the biotic and includes the aquatic, terrestrial, and atmospheric habitats. The environment is considered in terms of the most tangible aspects like air, water and food and less tangible though not less important, the communities we live in (Gorek, 1997). A pollutant is any substance in the environment which causes objectionable effects, impairing the welfare of the environment, reducing the quality of life and may eventually cause death. Such a substance has to be present in the environment beyond a set of tolerance limit, which could itself be either desirable or acceptable within the limit.

Thus, environmental pollution is the presence of a pollutant in the environment which may be poisonous or toxic and will cause harm to living things in the polluted environment (Duruibe et al., 2007).

Human Exposure to Heavy Metals through Food, Air, and Water

Heavy metal pollution of surface and underground water sources results in considerable soil pollution and the pollution tends to increase with increase in the dumping activities. Polluting the dumpsites soil leads to the pollution of the plants grown with that soil as farmers are gladly using dumpsite waste soil as source of fertilizer. These metals consequently accumulate in their tissues. Animals that graze on such contaminated plants and drink from polluted waters as well as marine lives that breed in heavy metal polluted waters also accumulate such metals in their tissues, and milk, if lactating (Habashi, 1992,

Garbarino etal., 1995; Horsfall and Spiff, 1999). People are, in turn exposed to heavy metals by consuming contaminated plants and animals, and this has been known to result in various biochemical disorders. In summary, all living organisms within a given ecosystem are contaminated along their cycles of food chain (Duruibe et al.,2007).

Heavy metal pollutants can localize and lay dormant, which can have severe effects on the environment through precipitation of their compounds or by ion exchange into soils and mud. Plants, mushrooms, or microorganisms are occasionally successfully used to remove some heavy metals such as mercury. Plants which exhibit hyper accumulation can be used to remove heavy metals from soils by concentrating them in their bio-matter (Duruibe et al.,2007).

Bio-importance of Heavy Metals Some heavy metals (such as Fe, Zn) are known to be of bio-importance to man and their daily medicinal and dietary allowances had been recommended. Their tolerance limits in drinking water have been reported. However, some others (like As, Cd, Pb, and methylated forms of Hg) have been reported to have no known bio-importance in human bio-chemistry and physiology and when consumed even at very low concentrations can be toxic (Nolan, 2003; Young, 2005, Duruibe etal.,2007).

Zinc is a ―masculine‖ element that balances copper in the body and is essential for male reproductive activity (Nolan, 2003). It serves as a co-factor for dehydrogenating enzymes and in carbonic anhydrase (Holum, 1983). Zinc deficiency causes anaemia and retardation of growth and development (McClugggage, 1991, Duruibe etal., 2007). Lead, cadmium and mercury have not been reported to have any known function in human biochemistry or physiology, and do not occur naturally in living organisms (Lenntech, 2004). Thus, dietary intake of these metals even at low concentrations can be very harmful because they bioaccumulate (Duruibe et al., 2007).

CHAPTER THREE

MATERIALS ANDMETHODS

Materials

Study area

Zaria Metropolis is located at latitude 11⁰ 07‘ N and longitude 07⁰ 42‘ E and is presently one of the most important cities in Northern Nigeria (Uba et al., 2008). It has total area of 300Km² and constitutes four major settlements, namely, Zaria City, Tudun Wada, Sabon Gari and Samaru covering two local government area: Sabon Gari and Zaria. It has problems of environmental sanitation such as improper disposal of refuse near residential areas resulting in contamination of the underground water via leachates emanating from the dumpsites since most of the wells near the dumpsites were poorly covered or not at all.

It has a tropical continental climate with a pronounced dry season, lasting up to seven months (October – May). During the dry season, a cold period is usually experienced between November and February. This emanates from the influence of the North-easternly winds (the harmattan) which controls the tropical continental air mass coming from the Sahara (Ahmadu Bello University, 2013). This weather prevails over most parts of the country. The North-East (NE) winds are characterized by hazy to dusty conditions and low temperatures, as low as 10⁰C at night. In the afternoon, up to 40⁰C is sometimes recorded. The humidity also drops to less than 15% in December/January (Ahmadu Bello University, 2013).

Zaria experiences a brief period of hot but dry weather in March and April, followed by a progressive incursion of tropical maritime air mass from the Atlantic Ocean which displaces the NE (Harmattan) winds. During this short period, the mean daily maximum temperatures are fairly stable, and range from 38 to 42⁰C (Ahmadu Bello University, 2013). The rainy season lasts from May to September/October with long-term annual rainfall of 1040mm in about 90 rainy days. The relatively deep tropical ferruginous soils and climate conditions of Zaria are suitable and can sustain a good cover of savanna woodland (Northern Guinea Savanna) with a variety of grasses woody shrubs and short trees (Ahmadu Bello University, 2013).

CHAPTER FOUR

RESULTS

Quality Assurance

The percentage recoveries of Pb, Cu, Cd, Zn and Hg for the sequential extraction and total metal determination of refuse waste-soil were presented in Table 4.1. The results of the percentage recoveries by sequential extraction of the soil were 92.63, 100.10, 100.05, 100.75 and 99.5% while those obtained by the total metal determination of the soil were 90.07, 85.02, 97.85, 98.10, and 95.0% for Pb, Cu, Cd, Zn and Hg respectively. Furthermore, the results of recovery experiment for underground water, leachates, blood, urine, hair and nails for the metals are presented in Table 4.2. The percentage recoveries of Pb, Cu, Cd, Hg and Zn in the samples are: 99.38±0.20, 100.005 ± 0.04, 99.40 ± 0.28, 99.75 ± 0.18 and 100.05 ± 0.04% for under groundwater, 99.40 ± 0.28, 98.40 ± 0.99, 99.90 ± 0.07, 99.35 ± 0.25 and 99.98 ± 0.05 for leachates, 95.89 ± 0.06, 102.14 ± 0.10, 99.51 ± 0.28, 92.79 ± 0.01 and 100.35 ± 0.25% for blood, 100.05 ± 0.04, 100.14 ± 0.10, 97.19 ± 0.13, 99.13 ± 0.09 and 100.45 ± 0.32 for urine, 99.25 ± 0.18, 100.05 ± 0.04, 97.25 ± 0.18, 99.05 ± 0.04 and 100.03 ± 0.02 for hair, and 97.35 ± 0.25, 98.33 ± 0.23, 91.25 ± 0.53, 97.40 ± 1.70, 99.45 ± 0.32% for nails, respectively.

CHAPTER FIVE

DISCUSSION

Quality Assurance

The percentage recoveries results of the soil samples for the sequential extraction as compared to total metal contents were presented in Table 4.1. The highest percentage recovery was recorded for Zn metal ion (100.75 ± 2.30 %) while Pb had the least percentage recovery of 92.63 ± 0.02 %. The trend in percentage recovery of the metals in the soil sample was Zn > Cd > Cu > Hg > Pb. Similarly, the percentage recoveries of metals in the other samples investigated were presented in Table 4.2. In the case of well water, all the metals exhibited excellent recoveries in the following trend; Cu = Zn > Hg > Cd > Pb, Cu and Zn being the highest 100.05 ± 0.04 % while Pb had the least percentage recovery of 99.38 ± 0.27 %.

Furthermore, in the case of dumpsite leachates, the trend was Zn > Cd > Pb > Hg Cu, and the highest and lowest recoveries of 99.98 ± 05 % and 99.35 ± 0.25 % were recorded for Zn and Hg, respectively. Also, the percentage recoveries of the metals recorded in the blood sample followed the trend Cu > Zn > Cd > Hg, thus, Cu and Hg showed the highest and lowest concentrations of 102.14 ± 0.10 and 92.79 ± 0.01%, respectively. Moreover, the trend of the percentage recoveries recorded in the urine and hair samples were; Zn > Cu > Pb > Hg > Cd and Cu > Zn > Pb > Hg > Cd, respectively, in which Cd exhibited the least percentage recovery while Zn had the highest as presented in Table 4.1. However, all the recorded percentage recoveries were within the acceptable ranges of > 90%. The ranges of the percentage recoveries as presented in Tables 4.1 and 4.2 were all within the acceptable range and the differences might be attributed to differences in leaching time, reagents and total volume of extractions (Ciba et al., 1999). Similar ranges have already been reported in literature for sequential extraction (Albores et al., 2000)

CHAPTER SIX

SUMMARY, CONCLUSION ANDRECOMMENDATION

SUMMARY

The study attempts to assess the impact of dumpsites to their immediate environments in Zaria Metropolis. In the cause of the research a questionnaire was administered as a guide to get some specific information about the residents (such as residency period, presence of wells, smokers, non-smokers etc). Findings from the study indicated that the major constituents of the dumpsites were polythene bags, wood, plastics and textile materials and the composition of the refuse wastes vary from one season to another with the relative abundance of the particle size in the order sand > silt > clay, this shows that the refuse waste soils were sandy-loamy in nature and may have poor water and metal retention capacities. Also, the bioavailability studies were carried out on the refuse waste soils, leachates and well water samples to determine the metals that would be easily released into the environment. Overall, the trend of the bioavailability of the metals in dumpsite leachates was Zn > Cd > Pb > Hg > Cu. The levels of Zn, Cd, Cu and Hg in the dust particulates were positively correlated with those in the soil with few exceptions, indicating their common pollution sources. In addition, the transfer of toxic metal ions through the food chain was investigated using chickens as bio-indicators across the sites and seasons. It is interesting to note that the organs that were mostly contaminated by all the analysed metals in the chicken samples were muscles, gizzard, and oesophagus while kidney was mostly contaminated by cadmium and zinc, the brain samples of the chickens were also polluted by lead metal ions. The mercury affects mostly the leg, feather, head, kidney, etc. However, zinc and copper which are essential elements were mostly found to accumulate more in the leg, skin, liver, gizzard and oesophagus and the bioaccumulation was more pronounced in the liver which was attributed to the roles it plays in the entire body system. Similarly, the urine, blood, nail and hair samples of human residents were investigated for possible metal poisoning, the concentrations of Cu and Zn in these samples were below the standard limits while those of Cd, Pb and Hg were generally above the standard limits across the sites. Excellent recoveries were obtained for Pb, Cd, Cu and Hg while, the % recovery was very poor for Zn which was attributed to its reduction potential. The non-toxic bismuth electrode was designed and tested which shows the detection limits of 0.005, 0.029, 0.033, 0.027 and 0.570µM for Cu, Pb, Zn, Cd and Hg, respectively.

CONCLUSION

Overall, the results of the analyses revealed that leachates, refuse waste soil, underground water, particulate dust and chicken samples were heavily polluted by Cd, Pb and Hg. Similarly, the samples of human residents‘ urine, blood, nails and hair samples were also contaminated by same toxic metals and this would pose serious health threat to the populace at the vicinity of these dumpsites resulting in metabolic disorder. Also, the pollution of the particulate dust, underground water and chicken samples at the vicinity of the dumpsite consequently affect the residents through the food chain transfer. The electro- analytical method could be used to determine the bioavailable fractions of these metals at cheaper rate especially when the sample size is large. Low concentrations were generally detected by the SWV as compared to ICP-OES technique indicating that an electro- analytical technique would be suitable for speciation studies of metals in the environmental samples. There is need to improve the detection limit of bismuth electrode to accommodate more metals with high degree of precision.

RECOMMENDATIONS

It is recommended that

The well water at the vicinity of the dumpsites should be treated thoroughly before use to minimize the adverse health effects such as kidney impairment, cancer, mental development in infants, toxicity to the central and peripheral nervous system associated with mercury, cadmium and leadbio-accumulations.
The novel electrochemical method (especially the stripping method) should be adopted to save the cost of analysing large number of samples as the method was validated with good recoveries with the exception of Zinc, thus more work should be done to improve the performance of the
Kaduna State Environmental Agency (KEPA) should ensure that the generation of hazardous waste is minimized and also provides adequate refuse waste disposal facilities. iv.KEPA should also ensure environmentally sound management of wastes by preventing and punishing illegal

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