SOURCE IDENTIFICATION AND VARIATION IN THE CHEMICAL COMPOSITION OF RAINWATER IN THE COASTAL AND INDUSTRIAL AREAS: A CASE STUDY OF IKOT ABASI, SOUTH-EASTERN NIGERIA

ABSTRACT

Studies on precipitation Chemistry were carried out with the aim to understand the nature and sources of rainwater at Utaewa (Location 1), a coastal village and Ikpetim, near Ibom Power Station (Location 2), all in Ikot Abasi Local Government Area, southern, Nigeria.These locations respectively represent the coastal and industrial regions.The rainwater samples, collected at these locations, were analyzed for major cations, anions, electrical conductivity and pH with the aim of identification of variation in the physiochemical compositions of the rainwater samples.The analysis of the rainwater samples gave a pH at locations 1 and 2 as 5.62 ± 0.26 and 5.77± 0.25 respectively during the wet season, while the pH of the rainwater at locations 1 and 2 during dry season were 5.41 ± 0.14 and 5.84 ± 0.21 respectively.The pH values indicated acidic water and were below the World Health Organisation (WHO) Standard of 6.5 to 8.5, but close to the World Meteorological Organisation (WMO) optimum pH value of 5.6 for rainwater from unpolluted continental areas.The predominance of  − and + were observed in the coastal environment whereas, calcium, sulphate, nitrate and ammonium ions predominate in industrial environment where there are power generating plants, Aluminium smelting company and gas station.The total anion (37.9%) at Utaewa is less influenced by anthropogenic activities whereas total anion (72.5%) at Ikpetim, near Power Plant is influenced by pollutants emitted by anthropogenic activities.The ratio: + /(NO3 -+ SO4 2-) was observed as 0.04 and 0.008 for Utaewa and Ikpetim respectively, which are close to zero, indicating that 99 % of acidity in the rainwater is neutralized in the study area with no consequence of acidity impact on the soil, surface waters and groundwater in the study area.Ca 2+ , K + and Na + play important roles in neutralization of acidic ions in rainwater.For source identification, correlation matrix analysis was established, which showed that at locations 1 and 2,strong correlation exists between the acidic ions SO4 2-and NO3 -, indicating their origin from anthropogenic activities.This is viewed to be attributed to the similarity in their behaviour in precipitation and the co-emissions of their precursors, which are SO2 and NO2.The major ion enrichment factors (EF) followed the order at location 1 during the dry season; 2+  + ⁄ (8.58) > +  + ⁄ (4.32) > 4 2−  + ⁄ (0.68) > −  + ⁄ (0.11), while the enrichment factor (EF ) during the wet season at location 1 followed the order ,  2+  + ⁄ (11.92 )> +  + ⁄ (3.78) > 4 2−  + ⁄ (0.88) > −  + ⁄ (0.11).

INTRODUCTION
With the noticeable fast economic and population growth in Nigeria in recent time, there is great concern on the global trend in wet precipitation Chemistry and its impact on the ecosystem.Long-term variation in the chemical pollutants characteristics of dry and wet depositions provides veritable data on the temporal evolution of atmospheric pollution, and can be engaged as a pertinent indicator to evaluate natural processes and anthropogenic activities (Tang et al., 2005;Yang et al., 2012).Wet deposition always play a more important role in flux compared to dry deposition, with chemical analyses of precipitation enabling a partial assessment of local air quality (O¨ zsoy et al., 2008).In Nigeria, acid deposition has been one of the most significant environmental issues since the discovery of oil decades ago (Etesin et al., 2013).Ikot Abasi is located out of the south of the Niger Delta region impacted by oil bunkering and gas emissions from anthropogenic activities, which may likely cause acid rain in the area.
However, high concentrations of air pollutants in and around Niger Delta in Nigeria most likely lead to high loadings of various chemical species to the ecosystem through atmospheric wet depositions (Etesin et al., 2012).According to the average concentrations of sulphate and nitrate in fine particles, which are two dominant acidic species were much higher than those in some cities suffering severe acid deposition in southern China (Yang et al., 2011).Considering the fast economic and population growth, urbanisation, increased vehicular traffic, the trend in precipitation chemistry and its influence on the ecosystem are of great concern, globally.In developing countries, several sources contribute to the presence of chemical pollutants in atmospheric air and precipitations such as, their natural resources, vehicular emissions, industrial and residential sources (Forehead and Huynh, 2018).Incidentally, poor air quality on people's behavioural factors and psychological health has resulted to low life expectancy in polluted areas (Qin et al., 2021).
The inhaled fine airborne particulate matters (PM2.5) may likely settle in the lungs, having the potential to cause many health problems (Anderson, 2009).A five-year study of wet precipitation in Beijing, China, reported that the acidification of rainwater is evidently on the increase, especially under the background of complex air pollution (Dingetal., 1997;Wang and Zhang, 1997;Feng et al., 2001;Hu et al., 2005;Yang et al., 2012).Also, recent studies showed that pH and precipitation chemistry in Beijing were noticeably different before and after the year of 2000, which was likely related to the variations in atmospheric pollution type (Tang et al., 2005;Hu et al., 2005;Xu and Han, 2009).According to the reports, there are no studies that are based on long-term surface measurements to track the changing precipitation chemistry along with the changing emissions of acidic precursors and neutralizing substances in Beijing after 2000.
Many studies have investigated the contamination of environment and human health following bombing.A group researchers have determined trace metals in water samples from harvested rain water with health issues correlated with the contents of these contaminants (Alaani et al., 2011).Dissolved chemical compositions in rainwater have provided valuable information on the pollutant sources in the atmosphere and short-term environmental changes (Alaani et al., 2011;Thomas et al., 2020;Ekanem et al., 2021).There are evidences that are well documented which implicated flaring of gas as a serious contributor to acid-rain in the Niger Delta ,with environmental impacts such as vegetation damage , corrosion of roofing sheets and death of aquatic lives (Daily Trust Newspaper, 2008;Amadi et al., 2014 ;Amadi and Akobundu, 2014).
Globally, the flaring of gas is estimated to be about 115 billion cubic meters of gas on annual basis (Stan, 2002).
In a similar report, also implicated the flaring of gas in Niger Delta, with attendant contribution to greenhouse gases more than all other sources in Sub-Saharan Africa combined (World Bank, 2004).Oil production in the Niger Delta of Nigeria started more than fifty years ago with the obnoxious practice of flaring associated gas.However, in the developed countries, the usual practice is re-injection of associated gas into the ground compared to the burning off into the atmosphere with no consideration of environmental and health consequences.Despite regulations introduced by the regulating agencies for more than 20 years to outlaw the practice, the associated gas is being flared by the oil companies with impunity, causing local pollution and contributing to climate change (Daily Trust Newspaper, 2008).
In this study, a precipitation monitoring program in Ikot Abasi is initiated in order to evaluate the magnitude as well as temporal trends and sources of acids and toxic substances in atmospheric depositions.Additionally, this study aims at summarizing the major findings with focus on the temporal variations in the precipitation chemistry and discusses possible mechanisms influencing these variations.Our hypothesis testing is that the acidity in the rainwater of the study area is increasing due to the combined effects of increasing SO2 and NO2 emissions from anthropogenic activities, beyond neutralizing ions in the rainwater compared with any other published data.

The Study Area
The study area in Ikot Abasi lies within the Niger Delta zone in Nigeria (Figure 1).et al., 2011a, b, c;Etesin et al., 2013;Akpan et al., 2020a;George, 2020;Etesin and Iniemem, 2021).The climate of the area is characterized by distinct wet and dry seasons.The wet season begins in April and last still November, while the dry season begins in November till March.A short period of draught is usually experienced in July and August, while a period of harmattan characterized by cold dry winds and lower temperatures normally occurs between December and February (Moses, 1979;Enemugwem, 2009;Nduka and Orisakwe, 2010;Obianwu et al., 2011).
The study area is characterized by a humid tropical climate with rainfall reaching about 3000 mm per annum (Evans et al., 2010;Ibanga and George, 2016;George et al., 2018;Igbemi et al., 2019: Ikpe et al., 2022;George, 2021;Ekanem et al., 2022).The mean annual daily evaporation of the area is 4.6 mm per day (Edet and Ntekim, 1996).Deposits of recent alluvium and beach ridge sands occur along the coast and the estuaries of the Imo and Qua Iboe Rivers and also along flood plains of creeks (Uwa et al., 2019;Umoh et al., 2022a).The study area consists of mainly of Coastal Plain sands.The sands are mature, coarse and moderately sorted.The Coastal Plain sands, otherwise known as the Benin Formation, overlie the Bende-Ameki Formation and dips south-westward (Mbonu and Ebeniro, 1991;Akankpo andIgbokwe, 2011: Ibuot et al., 2013;Obiara et al., 2015;Obiora et al., 2016;Akpan et al., 2020b;Inim et al. 2020;George et al., 2022).The landscape of Ikot Abasi comprises generally, low-lying plain and riverine areas with no portion exceeding 175 m above mean sea level.
The physiography of the study area is that of a Beach Ridge Complex characterized by a succession of sub -parallel sand ridges (George et al., 2015;Ituen and Edem, 2016;Ibuot et al., 2017;Umoh et al., 2022b).

Collection of Rainwater Samples
The set up for the collection of rainwater samples is indicated in Figure 2 and the harvested samples were stored in polyethylene bottles in icecooled containers and transported to the Laboratory for chemical analyses.The rainwater samples were collected to cover dry season (October 2020 to March, 2021) and wet season (May to September, 2021).A total of four (4) rainwater samples were collected on event basis during the two seasons specified at two locations representing coastal area (Location 1 -Utaewa) and industrial area ( Location 2 -Ikpetim, near Power Station),that were selected after field survey and were analysed for pH, conductivity, total dissolved solids , total petroleum hydrocarbons , temperature, dissolved oxygen, redox potentials, major anions (chloride, nitrate, sulphate , phosphate ), major cations ( calcium, sodium, potassium, ammonium) and heavy metals (iron, chromium, lead, cadmium , manganese,vanadium).

Physical Parameters of The Rain Waters
The rain water sampling and analyses were carried out in accordance with American Public Health Association, standard for sampling and analysis of water and wastewater (APHA, 2005).The physical parameters such as pH and conductivity, dissolved oxygen, temperature were determined on the field using a Gallenkamp pH meter and Hach conductivity meter WPA 400 digital model and dissolved oxygen meter respectively.

Analyses of Major Anions
Major anions (chloride, nitrate, sulphate, phosphate) were determined in accordance with American Public Health Association, standard for sampling and analysis of water and wastewater (APHA, 2005).Chloride content of the rain waters was determined by argentometric titration according to method No. 4500-Cl, B. of APHA, 2005.Sulphate content was determined by turbidimetric method, according to method No. 4500 SO4 E of (APHA, 2005).Nitrate was determined by spectrophotometric method, according to method No. 4500 NO3, B of (APHA, 2005).Phosphate content of the rainwater samples were determined by spectrophotometric method, according to method No.4500 -P, C of (APHA, 2005).

Analyses of Major Cations and Heavy Metals
Major cations (calcium, sodium, potassium, lead, cadmium, chromium, vanadium, manganese, iron) were determined in accordance with American Public Health Association, Standard Methods for sampling and analysis of water and wastewater (APHA, 2005).Calcium, sodium potassium, lead, cadmium, chromium, manganese, vanadium and iron were determined in the rainwater samples harvested by inductively coupled plasma -optical emission spectrometer (AGILENT 720 ICP-OES).
The Agilent 720-ES with megapixel CCD detector was used, which provided simultaneous measurement while the Agilent SPS3 autosampler was used for sample introduction.Agilent Expert II Software was used to control the instrument and acquire data.
Calibration and Quality Control (QC) solutions were prepared from the following reference materials: • Accustandard QCSTD-27 multi-element solution AG-QCS27-ASC-1 • Agilent Calibration Mix Majors 6610030700 • Agilent Calibration Mix2 6610030600 • Agilent ICMS Internal Standard Solution 6610030400 • Ultrapure Merck Lichrosolv water was used for dilution of standards and quality calibration solutions.
These were also stabilized in high purity 2% v/v concentrated nitric acid (HNO3).Appropriate concentrations ranges of working standards from the multi-elements stock standard were prepared through serial dilution method.A new worksheet was created from the ICP-OES Expert software into which was programmed the individual sample codes as well as the method with the parameters set according to the Manufacturer's manual.Ammonium ion was determined by macrojeldahl method according to method No.4500 NH3 B and Cof APHA, 2005, which will involve distillation and titration of the liberated ammonia.

Data Analysis and Calculations
The total cation percent and total anion percent were calculated based on the major cations, Ca 2+ , Na + , K + , NH4 + and major anions, SO4 2-, Cl -, NO3 - determined.The ratio of the total anions and total cations was calculated as Total anions / Total cations, to indicate the predominance of the ions in the atmosphere (Xing et al., 2017).
The neutralization factors (NF) were calculated using the following equation for the base cations: where, Xi is the base cation of interest, i.e., NH4 + , Ca 2+ , Na + , K + The acidifying potential (AP) of the acidic anions were calculated to indicate the acidifying capacity of gaseous oxides in the atmosphere as: The neutralising potential (NP) was calculated to indicate the neutralising capacity of base cations in the atmosphere as: The ratio of NP / AP, will be calculated and compared to the optimum value of 1.2, indicating the predominance of base cations in the atmosphere to neutralise the acidic anions (Hontoria et al., 2003;Xing et al., 2017;Salve et al., 2008).Ratios such as (NO3 -+ Cl -) / SO4 2-, NH4 + /NO3 -, NH4 + /SO4 2-and Cl -/Na + are calculated to indicate the possible predominance of these ions in the atmosphere.The enrichment factor (EF) was calculated for each element in the atmosphere by comparing the ratios of the elements measured in precipitation versus the ratios of elements present in standard seawater.In this study, the sodium ion (Na + ) was chosen as the reference element for the marine origin elements (Xing et al., 2017).The equation for the enrichment factor calculation can be expressed as: where, X is the concentration of a specific ion (μeq/L).[X/Na +] marine is the ratio of seawater reported (Keene et al., 1986).Also to show similar sources of chemical species, Pearson's correlations were calculated between major rainwater ions determined.

H + /(NO3 − +SO4 2− ) ratio
The ratio of H + /(NO3 − +SO4 2− ) in ueq/L as observed by is also an indicator for the determination of the extent of neutralization process in rainwater (Seinfield, 1986).The ratio close to zero indicates extensive neutralization whereas values close to one indicate lack of neutralization in rainwater (Salve et al., 2012).

RESULTS AND DISCUSSION
The results of analyses of the rainwater samples from Ikot Abasi, Akwa Ibom State , Nigeria are presented in Tables 1 and 2for the wet and dry Seasons respectively.

pH and Electrical Conductivity of Rainwater
The pH of the rainwater at locations 1 and 2 were 5.62 ± 0.26 and 5.77± 0.25 respectively during the wet season (Table 1), while the pH of the rainwater at locations 1 and 2 were 5.41 ± 0.14 and 5.84 ± 0.21during the dry season respectively (Table 2).The pH values indicated acidic water and were below the WHO Standard of 6.5 to 8.5, but close to the WMO optimum pH value of 5.6 for rainwater from unpolluted continental areas (Tang et al., 2000;Berner and Berner, 2012).The electrical conductivity of the rainwater at locations 1 and 2 were 8.78 ± 0.78 and 8.45± 0.68 respectively during the wet season (Table 1), while the electrical conductivity of the rainwater at locations 1 and 2 were 10.19 ± 0.25 and 12.65 ± 0.06 during the dry season respectively (Table 2).The electrical conductivities were below the WHO Standard of 50 uS/cm, but close to the WMO optimum value of 14.6 for rainwater (Tang et al., 2000).

Total Cations and Anions
The total cations obtained during the dry season at locations 1 and 2 were 62.6 % and 57.2 % respectively, while the total anions obtained during the wet season at locations 1 and 2 were 37.4 % and 42.8 % respectively.The total cations obtained during the wet season at locations 1 and 2were 66.7 % and 59.8 % respectively, while the total anions obtained during wet season at locations 1 and 2 were 33.3 % and 40.22 % respectively.Locations 1 and 2 show increase in total cations than total anions during both seasons.

Total Anion and Total Cation Ratio
The ratios of total anion/total cation of the rainwater were 0.61 and 0.75 at locations 1 and 2 respectively during the dry season, while the ratios of total anions /total cations were 0.51 and 0.67 respectively at locations 1 and 2. Overall, the ratio of total anions /total cations were less than one , suggesting an anion deficiency ascribed to some unmeasured anions such as carbonates and short chain organic acids as observed (Hontoria et al., 2013).

Cl -/Na + Ratio
The ratios of  − / + of the rainwater during the dry season at locations 1 and 2 were 0.35 and 0.31 respectively, while the ratio of  − /Na + of the rainwater during the wet season at locations 1 and 2, were 0.19 and 0.24 respectively (Table 3) .The values of the  −  + ⁄ ratio at locations 1 and 2 during the dry and wet seasons were less than one as compared to  −  + ⁄ ratio of 1.16 for seawater by the WMO (Tang et al., 2000).The results indicated the high sodium ion contribution to the atmosphere from the seawater due to the proximity of the study area to the Atlantic Ocean.( 3 − +  − )/SO4 2-Ratio.The ratio of ( 3 − +Cl -)/SO4 2-(Table 3) gave values of 1.03 and 0.66 at locations 1 and 2 respectively during the dry season, and 0.92 and 0.81 at locations 1 and 2 respectively during the wet season.The results indicated equal contribution of the 3 − ,  − and SO4 2-anions from anthropogenic activities in the study area to the acidity of the rainwater at location 1 during the dry season.However, the wet season results indicated the increase in the concentration of sulphur oxides from anthropogenic activities to the acidity of the atmosphere, which culminated in the increase of sulphate ion in the rainwater.

NH4 + / NO3 -Ratio
The ratio of NH4 + /NO3 -ions were 1.17 and 0.86 at locations 1 and 2 respectively during the dry season (Table 3), while the ratio were 0.66 and 0.45 at locations 1 and 2 respectively during the wet season .All the values were less than one, except at location 1 during the dry season, indicating the predominance of NH4NO3 in the atmosphere in the study area from anthropogenic activities.

NH4 + / SO4 -Ratio
The ratio of NH4 + /SO4 -at locations 1 and 2 were 0.28 and 0.24 respectively during the dry season, while the ratio at locations 1 and 2 were 0.25 and 0.21 respectively during the wet season (Table 3).All the values at locations 1 and 2 were less than one during the dry and wet seasons, indicating the predominance of (NH4)2SO4 in the atmosphere from anthropogenic activities, in the study area.

NO3 -/SO4 2-(nss) Ratio
The non-sea salt ratio of NO3 -/SO4 2-(nss) in the rainwater were 0.25 and 0.51 at locations 1 and 2 respectively during the dry season, and were 0.39 and 0.45 at locations 1 and 2 respectively during the wet season (Table 3) .All the values were less than one, indicating that the precipitating acidity is predominantly from non-sea salt sulphur oxides as emissions from anthropogenic activities, and progressively substituted by nitrogen oxides NOx (Pradeep et al., 2012).

Ca 2+ / Na + Ratio
The ratio of Ca2 + / Na + ions in the rainwater at locations 1 and 2 were 1.24 and 0.81 respectively during the dry season, while the wet season values at locations 1 and 2 were 0.90 and 0.66 respectively (Table 3).The value at location 1 during the dry season was greater than one, indicating the predominance of calcium ion in the atmosphere as a result of crustal components abundance.However, other locations had values that were less than one, indicating the predominance of sodium ion in the atmosphere which may have been influenced by the sea salt water from the Atlantic Ocean by proximity (Yang et al., 2012).

Neutralisation Potential / Acidification Potential Ratio (NP/AP)
NP/AP ratio of the rainwater at locations 1and 2 were 2.42 and 1.00 respectively during the dry season (Table 3), while the NP/AP ratio of the rainwater at locations 1and 2 were 2.04 and 0.81 respectively during the wet season.The NP/AP ratio values at location 1 were higher during dry and wet seasons than the optimum value of 1.2, indicating the predominance of neutralising potential of the wet precipitation (Salve et al., 2008).The NP/AP ratio values greater than the optimum value of 1.2, correlates with higher concentration of calcium ion in the study area as a major acid neutralising factor in the atmosphere (Xing et al., 2017).

Correlation Matrices
Pearson's correlation matrix of major ions in the rainwater is presented in Table 5. p H values of the rainwater correlates with sulphate ion ( R = 0.64) and very strongly with nitrate ion ( R = 0.86 ), but not correlate with chloride ion ( R = -0.26),Calcium ion (R= -0.02 ) , potassium ion ( R= -1.27 ) , sodium ( R = 0.023) and less with ammonium ion (R= 0.38) , indicating strong contributions of sulphate and nitrate ions to the acidification of the acid rain (Salve et al., 2012).(Salve et al., 2012).

Major Ion Ratios and Enrichment Factor (EF)
The major ion enrichment factor (EF) by micro equivalent per litre (ueq/L) followed the order at location 1 during the dry season; Ca 2+ / Na + (8.58) > K + / Na + (4.32 ) > SO4 -2 / Na + (0.68) > Cl -/Na + ( 0.11) , while the enrichment factor (EF ) during the wet season at location 1 follow the order Ca 2+ / Na + (11.92) > K + / Na + (3.78) > SO4 -2 / Na + (0.88) > Cl -/Na + (0.11), (Table 6).The sea salt fraction for Ca 2+ / Na + was 11.65 percent, and non-sea salt fraction was 88.35 per cent at location 1 during the dry season ,while K + / Na + had sea salt fraction and non-sea salt fraction of 23.13 percent and 76.87 percent respectively (Table 6), indicating the sources of calcium and potassium ions from crustal abundance.The sea salt and non-sea salt fractions of Cl -/Na + had values of more than 100 percent and less than zero percent respectively, during the dry and wet season at location 1, indicating the source of chloride ion in the rainwater from sea salt evaporation.At location 1 during the wet season, The sea salt fraction for Ca 2+ / Na + was 8.39 percent, and non-sea salt fraction was 91.61 percent, while K + / Na + had sea salt fraction and non-sea salt fraction of 26.43 percent and 73.57percent respectively (Table 6), which indicated same source contribution for calcium and potassium ions from crustal abundance in both seasons, as compared to the sea salt and nonsea salt fractions of more than 100 percent and less than zero per cent respectively for Cl -/Na + ratio.At location 2 during the dry season, the enrichment factor for the major ions in the rainwater had the following order, Ca 2+ / Na + (6.33) >K + / Na + (3.24) >SO4 -2 / Na + (1.32)>Cl -/Na + (0.08), (Table 7).In comparison with the values obtained during the wet season, the order were , Ca 2+ / Na + (7.75) >K + / Na + (3.51) > SO4 -2 / Na + (1.48)>Cl -/Na + (0.18), (Table 7), indicating the dominance of calcium , potassium and sulphate ions in the rainwater from anthropogenic activities and crustal abundance.At location 2 during the dry season, Ca 2+ / Na + had sea salt and non-sea salt fractions of 15.79 per cent and 84.21 per cent respectively; K + / Na + had sea salt and non-sea salt fractions of 30.83 per cent and 69.17 percent respectively ; SO4 -2 / Na + had sea salt and non-sea salt fractions of 75.76 per cent and 24.24 per cent respectively; Cl -/Na + had sea salt and nonsea salt fractions of greater than 100 per cent and less than zero respectively (Table 7).In comparison during the wet season, Ca 2+ / Na + had sea salt and non-sea salt fractions of 12.91 per cent and 87.09 per cent respectively ; K + / Na + had sea salt and non-sea salt fractions of 28.46 per cent and 71.54 per cent respectively ; SO4 -2 / Na + had sea salt and nonsea salt fractions of 67.57per cent and 32.43 per cent respectively; Cl - /Na + had sea salt and non-sea salt fractions of greater than 100 percent and less than zero respectively (Table 7).The results of major ions obtained during both seasons indicated that calcium and potassium ions are dominant in the rainwater from the study area from terrestrial origin; chloride ion is not dominant in the rainwater from the marine origin, while sulphate ion is however, dominant in the rainwater from anthropogenic activities in the study area.

H+/(NO3 − +SO4 2− )
The ratio of H+/(NO3 − +SO4 2− ) in ueq/L as observed by is also an indicator for the determination of the extent of neutralization process in rainwater (Seinfield, 1986).In this study the values determined at location 1 for dry and wet seasons were 0.08 and 0.11 respectively, while the values determined for Location 2 were 0.03 and 0.02 during the dry and wet seasons respectively (Table 8).The ratio close to zero indicates extensive neutralization whereas values close to one indicate lack of neutralization in rainwater (Al-Chessman, 2005;Salve et al., 2012).The ratios determined for all the locations in both seasons were close to zero, indicating that 99 % of acidity in the rainwater is neutralized in the study area.The results corroborate the observations by in acid rain study in Warri and Port Harcourt, Niger Delta (Efe and Mogborukor, 2012).

CONCLUSION
This study investigated the concentration and composition of major ions in rainwater at Utaewa (Location 1) and Ikpetim (Location 2), in Ikot Abasi , southern part of Niger Delta, with an aim to characterize the chemical composition of rainwater and identify possible sources.The p H of the rain waters in the two locations had values in the acidic range in both seasons; some values were less than the optimum p H of 5.6 for rainwater.In all locations in both seasons, the ratio of Total anions to Total cations were less than one, which clearly indicated major anion deficit.Neutralisation Factor for the base cations during the dry season at Location 1 follows the order NFCa > NFNa > NFK>NFNH4 , and at location 2 , follows the order NFNa> NFCa> NFK> NFNH4 , and same sequence repeated during the wet season.Significantly, the major neutralisation base cations were calcium ion , sodium ion , potassium ion.The correlation matrix showed a strong correlation between sulphate, nitrate and ammonium ions, which shows a common source of the ions from anthropogenic activities like the emissions from the Power Plant in the study area.Sodium ion correlates strongly with chloride ion, which shows a common source from sea salt spray ferried by wind from the Atlantic Ocean due to proximity to the study area.The ratio of H+/(NO3 − +SO4 2− ) measured in ueq/L in both locations and seasons were less than one , which indicated complete neutralisation of the acidity in rainwater in the study area with no consequence of acidity impact of the soil, surface water and groundwater.This observation is corroborated by the significant enrichment of the base cations from the Enrichment Factor measured.

Figure 1 :
Figure 1: Map of study area showing Utaewa and Ikpetim, location of sample collections.

Figure 2 :
Figure 2: Diagram showing rainwater collection in the study area

Figure 3 :Figure 4 :
Figure 3: Plot of Physicochemical Parameters during Wet Season It is located between latitude 4.3111 o and 4.4512 o N and between longitude 7.5213 o and 8.0219 o E (Ikot Abasi: The Aluminium Town, 1997; Etesin and Iniemem, 2021).Ikot Abasi is a local government in Akwa Ibom State that hosts some major multinational companies, like Exxon Mobil, Aluminium Smelter Company of Nigeria (ALSCON), SEPTA gas station, Ibom Power Company Limited, Ikot Abasi and Oil Platforms close to Iko Town in Eastern Obolo.The study area is underlain by the sedimentary formation of the Late Tertiary and Holocene ages (Obianwu

Table 1 :
Results of Physicochemical Analyses of Rain Water From Ikot Abasi, Nigeria ,During Wet Season

Table 2 :
Results of Physicochemical Analysis of Rainwater from Ikot Abasi, Nigeria During Dry Season

Table 3 :
Rain Water Parameters for Wet Season and Dry Season

Table 4 :
Neutralization Factor of Base Cations

Table 5 :
Pearson Correlation of Rain Water Parameters

Table 6 :
Major ion ratio in rainwater at Location 1

Table 7 :
Major ion ratio in rainwater at Location 2

Table 8 :
Major Ion Concentration in Micro Equivalent Per Litre