Analyses of Some Selected Heavy Metals and Contaminants in Underground Water and Three Satellite River Stations in Owerri Local Government Area of Imo State.
CHAPTER ONE
OBJECTIVE OF THE STUDY
- A pollution watch of the underground and surface water contaminants in old Owerri Local Government Area of Imo This entails sampling and analyzing ground water for quality investigation of water which might be contributing to pollution.
- To establish, where possible, a relationship between the pollution indices of the water bodies and the pollutants in the area of study.
- Utilization of the information realized in controlling future contaminations of the environment by the pollutant.
- To design a possible scientific and effective control measure to remove contaminations in these areas.
CHAPTER TWO
LITERATURE REVIEW
For the protection of human health, guidelines for the presence of heavy metals in water and contaminants have been set by different international organizations such as WHO, USEPA, EPA, and EUC, thus heavy metals have maximum contaminant level [mcl] which is enforceable standard set at numerical values with an adequate margin of safety to ensure no adverse effect on human health set by WHO. Marcovechio et al 2001 [56].
In 1932, Bartow and Weighe carried out analysis and discovered the presence of zinc in water supplies meant for homes in England though at concentration of less than 20µmg/dm3 [57]. In 1934 Anderson et al worked on the corrosion of zinc in various water bodies in America, Washington D.C., the presence of zinc was not of any major health consequence though it was confirmed present at a concentration less than 0.2mg/dm3 [58]. Florence and Batley[1976] did a work which traced the presence of heavy metals in sea water by a chelating resin process . [59].
Brooker and Johnson[1984 ]studied the behaviour of phosphates, nitrates, chlorides and hardness in twelve Welsh rivers. The chloride concentration was in the range of 11.0 mg/dm3 to 42mg/dm3 between the periods of 1994 to 1981 [60].
In 1986, Friberg et al published a report that the cadmium concentration of a Swedish drinking water was of a concentration 5mg/dm3 in areas where the soil had been acidified. About a decade later some publications also came out on the concentration of zinc up to 24mg/dm3 from about 600 wells in Amsterdam. This health situation resulted in excessive vomiting, stomach crops and diarrhea [61,62].
In 1984, Chievers and Caygil [63] reported on the high nitrate level in well water in the United States of America [63]. Young children consuming high nitrate well waters were reported in 1983 by Grain et al [64] in the United States of America leading to vomiting and nose running etc.
In 1987, Phelan was concerned about the chloride levels in the coastal aquifers of Washington D.C in his geographical survey report in (Maryland and Delaware districts [65].
Mustafa in 1988 made contributions in the cadmium concentration of 1- 2 🡖g/dm3 found in private wells in the Saudi Arabia. The work also reported of chronic oral exposure to this high concentration leading to kidney failures and impairement of sensory organs. [66]
In 2009, Mohammed and Gupta made studies on the Mumbai and Bead districts of India on heavy metals in pollution of ground water resources as an effect of municipal solid water dumping. Cu2+ was found to be in the range of 0.9mg/dm3 , Zn2+ 1.02 mg/dm3, Cr2+ 0.01 mg/dm3, Cd in 0.09 mg/l and Pb2+ 0.024 mg/dm3. The report indicated that the heavy metal lead was the cause of neurotoxins and most common type of human mental toxicosis, capable of causing irreversible brain damage [67].
Adesiyum et al in 1983 carried out studies on well waters (hand dug) and possible health risks in Kastina, Nigeria [68]. In the same year 1983, reports by Lawani and Imeokparia work on the distribution of nitrate in drinking water in Kwara state. The report indicated a level of about 0.94 mg/dm3 which showed slight pollution by nitrates [69].
CHAPTER THREE
EXPERIMENTAL METHODS
The testing of water samples consists of the following physical, chemical and microbial examination
The physical characteristics included colour, taste, odour and turbility while the chemical characteristics comprise of total solid, organic matter, hardness, alkalinity, acidity, pH, nitrogen as nitrate, nitrites, free ammonia, albuminoid ammonia, chlorides, sulphates, free C02, oxygen absorption and heavy metals. The microbiological examinations include plate count, coliform count, faecal streptococci test and clostridium welchi test.
The analyses of the parameters carried out in this project were done according to the methods outlined by APHA, AWWA-WPCF, standard methods for water and effluent 1996.
Experimental Method I
Atomic Absorption Spectrophotometric Determinations
This was determined by the method outlined in APHA-AWWA-WPCF
Pre treatment of sample for the determination of Fe, Cu, Pb, Mn, and Zn.
100cm3 of the well mixed sample was transferred into a beaker and 5.0cm3 of concentrated nitric acid added to it. The beaker was placed on hot plate and evaporated to near dryness making sure that the sample did not boil. The beaker containing the residue was cooled and another 5.00cm3 conc. HN03 added. It was covered with a watch glass and returned to the hot plate and heated until a gentle refluxing occurred. Heating was continued with additional concentrated HN03 as necessary until digestion was completed as signaled by a light coloured residue. Then 2.0cm3 of conc. HN03 was added and the beaker warmed slightly to dissolve the residue. The walls of the beaker and the watch glass were washed with deionized distilled water and the resultant solution filtered to remove silicate and other insoluble materials that clogged the atomizer before making up the volume to 50.00cm3.
Preparation of Standard Curve and Determination of the cation concentration
All the stock solutions prepared were equivalent to 1.0g metal in 1.0dm3 solution giving 1000mg/dm3 concentration. From these, standard solutions equivalent to 5.0, 10.0 and 15mg/dm3 concentration of the cation under determination were prepared. For example, 50cm3 of the 1000.00mg/dm3 solution diluted to 1000.00cm3 gave a 5.0mg/dm3 concentration
10.0cm3 of it diluted to 1000cm3 gave 10.0mg/dm3 (ppm) concentration etc. Each set of standard solution was fed into the computerized spectrophotometer which calibrates itself internally. After feeding the Atomic Absorption Spectrophotometer (AAS) with the calibrated concentration for each cation, the sample was aspirated into it and a direct reading of its concentration in mg/dm3 obtained.
PREPARATION OF SAMPLE SOLUTION
10cm3 of the water samples were introduced into a 250cm3 conical flask and 10cm3 of conc HCl was added followed by 25cm3 of conc Nitric acid, mixed and heated in a hot plate at a temperature not exceeding 500C for three hours, dense white fumes appeared and contents of the flask heated to dryness. The flask was allowed to cool in the dessicator in the fume cupboard. The solution was made up to 100cm3 mark and transferred to a plastic container, labeled and dated for analysis.
CHAPTER FOUR
RESULTS
The study assessed the level of heavy metals and contaminants in the underground and surface water in the old Owerri Local Government Area of Imo State for the period April through May to June 2009, using the Atomic Absorption Spectrophotometer Buck 2005 for the determination of the heavy elements (copper Cu, Iron Fe, Manganese Mn, Lead Pb and Zinc Zn) [143,131].
(i) Pb was seen to be the most prominent trace metal in the month of April 2009 with a concentration of 1.33031 mg/dm3 at site 2 under ground water, 1.0839 m/dm3 for site 3 respectively. The sites showed indications of high contamination concentration with a minimum value of 0.6978 mg/dm3 at the 4th site. The 2nd and 3rd sites are areas of heavy industrial activities spanning from mechanic villages, through refuse dump, and dense population. This is again evident in the high concentrations of other trace elements like zinc with a concentration of 0.6788 mg/L at the 2nd site. The high concentration of these trace elements is evident serious industrial pollution to the underground waters and in the period under study.
The figure indicates that different underground collection sites had one or more heavy element in high concentrations well above the WHO set standard. Iron was found at the 5th site with a conc of 0.875mg/dm3 not exceeding the WHO set standard. The element Cu also was found to be highest at the 5th point of analysis also, with a concentration of 0.9005mg/dm3 not exceedly WHO set standard.
(ii) The underground water samples analyzed. For the month of May 2009 had trace element cu as the most prominent with a concentration value of 3.636 mg/dm3 at the 3rd site followed by Pb at the 4th and 2nd site with 1.0158 mg/dm3 and 1.0077 mg/dm3 already. These values though high but only the 3rd site exceeded the WHO set standards by 0.636mg/dm3. The outrageous concentration of the trace metal copper seems to have identified a very recent dumping of the metal scrap within the vicinity of the site 3. This is because the site is close to one of the Federal Universities in the country and not much industrial activity takes place at that site. This therefore calls for an urgent visit to the site. The trace element Pb has been identified as a present contaminant of the water body, this may be due to the presence of auto- electrician at almost any corner of the street and the metropolis of Owerri and its environs. These underground water sources need a revisitation to ascertain the cause of the high level of Pb concentration.
CHAPTER FIVE
DISCUSSION
The result and analysis from the under ground water samples (Bore holes) from the Old Owerri Local Government Areas, Imo State, had in all the trace elements tested safe for human consumptions in line with World Health Organizations recommended standards in the locations and environs for the period of study with the exception of the element lead. The concentration of lead exceeded the 0.05mg/dm3. Tables 2,4,6.and Fig8,9and10 for the period April , May and June 2009 respectively.
For the the surface waters (Otamiri , Nworie and Oramiriukwa River) they had indications of concentrations of several of the trace elements within the WHO recommended range for drinking water excepting for some locations and periods.
The Otamiri River had for the month of April only the element Mn and Pb exceeding the 0.05mg/dm3 set standards by WHO. Table9,and fig20,
For the month of May 2009, Otamiri River had Pb and Mn in excess of the WHO set standards. Table 11 and Fig 21, for the month of June 2009, Otamiri River had Pb exceeding the value in the first two sites only. Table 13 and Fig 22.
The Nworie River in the month of April 2009 had only lead exceeding the 0.05mg/dm3 set standard Table 16 and Fig 33. For the month of May 2009, the Nworie River had Cu, Mn, and Pb exceeding the set standard of 1.0mg/dm3 0.05mg/dm3 respectively. (Table 18 and Fig34.
In the month of June 2009, Nworie River had Mn, and Pb exceeding the set standard values of 0.05mg/dm3.
The Oramiriukwa river had in the three months of study observed to have the trace elements Pb and Mn exceeding the WHO set standard. Of 0.05mg/dm3. Tables 23, 25 and 27 and Fig46,Fig47 and Fig48. An outstanding result was obtained in the month of June in relation to high concentration of Mn. This calls for investigation.
CONCLUSION AND RECOMMENDATION
The analysis and results of the underground (borehole) and surface water (rivers) in the Owerri Local Government Area of Imo State showed that anthropogenic activities in the area led to a heavy contamination of the water bodies with elements (both minor and major) which are hazardous to human health.
This contamination raised the pollution indices of these water bodies (underground and surface) far above the standard pollution index of 1.0 stipulated by WHO for a drinkable water; the consequence of this is that the ignorant inhabitants are making use of these heavily contaminated water to their detriment.
It is recommended that the state environmental protection Agency should periodically test the effluents from the industries that are deposited on the environment to ascertain their toxicity levels. State Environmental Protection Agency should periodically test these water bodies that are used by the people to ascertain their pollution index, so that when it is above the WHO stipulated value adequate procedures can be made to bring it to a safe and drinkable level.
The pollution index calculation which is 8.57mg/dm3 for the underground waters and minimum 30.30mg/dm3 for the surface waters shows some sort of pollution and additional treatment is required to reduce the impurities. The pollution is as a result of anthropogenic activities. The pollution levels in these water bodies should be checked to keep away water borne diseases and out break of epidemics.
Health Education programmes should be introduced to instruct users of the danger of drinking or coming in contact with contaminated water. [106]
A possible process of phyto-extraction of the water bodies should be evolved starting with the surface water bodies for now. This can be introduced by the use of boiler fly ash or planting of some herbs that are known to be absorbents of these heavy metals along the river banks, and when harvested, the surface water bodies would have been treated [105] and likewise the environs [106].
The chemical parameters of water resources in the Old Owerri LGA can better be discussed with a focus on the table below.
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