Ethiopian Journal of Environmental Studies & Management 10(4): 505 – 519, 2017. ISSN:1998-0507 doi: https://dx.doi.org/10.4314/ejesm.v10i4.8 Submitted: January 19, 2017 Accepted: May 31, 2017
ASSESSMENT OF WATER QUALITY OF OBUEYINOMO RIVER, OVIA NORTH EAST LOCAL GOVERNMENT AREA, EDO STATE, SOUTHERN NIGERIA
*ENUNEKU, A., 1 OKOH, H. 2 AND ORONSAYE, C. 3 1Department of Environmental Management and Toxicology, Faculty of Life Sciences, University of Benin, PMB 1154, Benin City, Nigeria. 2,3 Department of Animal and Environmental Biology, Faculty of Life Sciences, University of Benin, PMB1154, Benin City, Nigeria
Abstract This study was carried out to assess the water quality of Obueyinomo River using water quality index. Ambient and water temperatures were determined in-situ while total dissolved solids (TDS), total suspended solids (TSS), total solids (TS), turbidity, pH, conductivity, hardness, alkalinity, dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), chloride, nitrate, phosphate, calcium and magnesium levels were analyzed in the laboratory using standard techniques. With the exception of DO, the other physicochemical parameters showed no significant difference (p>0.05) across the stations. Distribution patterns of physicochemical parameters in stations 1, 2 and 3 were analyzed using PCA. There was a strong association for stations 1, 2 and 3 which was also highly associated with nitrates. Hardness, magnesium calcium and phosphate formed a cluster showing the contributions of these ions to water hardness. Alkalinity, suspended solids and chloride formed a cluster suggesting that the suspended solids are largely composed of chlorides. Turbidity, pH, BOD and DO at all the stations exceeded the Federal Ministry of Environment standards for surface water. The water quality index (WQI) values at stations 1, 2 and 3 were 138.45, 122.70 and 170.01 respectively. The parameters responsible for the high values of WQI as indicated by the water quality rating include turbidity, pH, dissolved oxygen and biochemical oxygen demand. The high WQI values in all the stations studied which exceeded the benchmark of 100 showed that the water from this river is unfit for drinking purposes and should be treated before consumption by inhabitants of the area.
Key Words: Physicochemical parameters, River, Water quality index, Contamination
Introduction Approximately one third of Nigerians Freshwater from rivers and streams live with moderate to high water stress are a necessity for human survival. (Olorode et al , 2015). Contamination Sustainable development will be an with hazardous chemicals and wastewater impossibility without freshwater of and sometimes natural sources is a adequate quality and quantity. common phenomenon (Ojekunle, 2000).
*Corresponding Author: Enuneku, A. 505 Email: [email protected]
Assessment of Water Quality of Obueyinomo River ...... ENUNEKU et al.
In Nigeria, most rural communities do aquatic ecosystems. All aquatic animals not have access to safe drinking water need oxygen to survive. (Egboh and Emeshili, 2007). Such rural pH expresses the acidity or alkalinity communities inhabiting the banks of of a solution on a logarithmic scale on rivers obtain water for domestic purposes which 7 is neutral. Lower values are from nearby rivers and streams which more acid and higher values more may be contaminated. This exposes them alkaline. Most aquatic animals prefer a to water borne diseases and contaminants pH range of 6.5 - 8.0. Lawson, (2011) which are known to pose serious health reported that aquatic shrimps and crabs problems (Odoemelam et al ., 2013). require optimum pH range of 6.8 - 8.7 for The maintenance of healthy maximum growth and reproduction. freshwater bodies is dependent on According to WHO (2011), there is no physicochemical properties and health-based guideline value for pH, biological diversity. Important physical although 6.5 – 8.5 is proposed for and chemical parameters that affect drinking water. natural water quality are temperature, pH, Nutrient enrichment of surface waters turbidity, dissolved oxygen (DO), has generated concern due to the biochemical oxygen demand (BOD), ecological impacts on both freshwater chemical oxygen demand (COD), and estuarine systems (Prior and Johnes, alkalinity, Nitrates and Phosphates 2002). Nitrogen and phosphorus species (Lawson, 2011; Nduka et al. , 2008). are notable characteristic pollutants for These parameters are principal factors for eutrophication of natural waters (Zanin et the survival of aquatic organisms al. , 1998; Omaka et al. , 2007). High (Lawson, 2011). Turbid water caused by concentrations of nitrates in drinking suspended and colloidal matter such as water sources can be fatal to humans and clay may be the result of soil erosion, animals (Zatar et al. , 1999Monteiro et al. , urban runoff, algal blooms, and bottom 2003). Elevated concentrations of sediment disturbances, silt, organic and phosphorus may result in fouling of inorganic matter, and microscopic natural water and production of toxic organisms (Murhekar, 2011). Alkalinity Cyanobacteria (Omaka, 2007). is commonly used to indicate a system's Studies of the physicochemical capacity to buffer against acid impacts. hydrology of water bodies in Nigeria Alkalinity due to the presence of have received a great deal of attention bicarbonate, carbonate and hydroxides of (Asonye et al . (2007); Anyanwu (2012); calcium, sodium and potassium Ekhator et al. (2012); Akubugwo et al. (Murhekar, 2011; Lawson, 2011) is vital (2012); Taiwo et al. (2014). Obueyinomo in neutralizing the acidity of water which River located in Agemopa community increases with dissolved carbon dioxide serves as the primary source of water for (Lawson, 2011). Temperature is one of drinking and various domestic purposes. the limiting factors in the aquatic Thus there is need to ascertain the environment (Lawson, 2011). If water suitability of the water from the river for temperature is outside the tolerable range domestic purposes. for a long time, organisms can be stressed The aim of this study was to assess and die. DO is important to health of the water quality of Obueyinomo River
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Ethiopian Journal of Environmental Studies and Management Vol. 10 no.4 2017 using water quality index (WQI). WQI is were collected between the hours of 7 00 a very useful and efficient method which to 10 00 GMT. can provide a simple characterisation of Sampling Stations water quality and it is based on Station 1 was located upstream of physicochemical parameters such as other stations and shaded by mesh of water temperature, turbidity, TSS, TDS, grasses and shrubs. This is located pH, DO, BOD, nitrate, chloride, between latitude N 06°37 ʹ467 ʹʹ and phosphate and calcium. longitude 005°34 ʹ49.1 ʹʹ E. The substratum is sandy mixed with decaying Materials and Methods organic matter. The water is cloudy and Obueyinomo River in Agemopa partly covered by some floating and community is located in Ovia North East emergent plants. Dominant plants at this local government area of Edo state station include Elaeis guineensis, Smilax (figure 1). The river is located located anceps and Dryopteris filixmax . No between latitude N 06°37 ʹ467 ʹʹ , longitude activity human was observed at this 005°34 ʹ49.1 ʹʹ E and latitude station. N06 o37 ʹ26.8 ʹʹ , longitude 005°34 ʹ31 ʹʹ . The Station 2 was located between climate around the river area consists of latitude N 06°o37 ʹ29.6 ʹʹ and longitude two seasons, the rainy season which 005°34 ʹ30.6 ʹʹ E. The plants that were starts from May to October and the dry observed in this station were Setaria season which starts from November to babarta, Elaeis guineensis, Heavea April. The region is a rainforest biome. brazilensis, Xanthosoma sagetefolius and The river is the primary source of water Palisota hirsuta . for drinking and other domestic activities Station 3 was located between by the villagers. The primary human latitude latitude N06°37 ʹ26.8 ʹʹ and activity in this community is farming. longitude 005°34 ʹ31 ʹʹ E. The substratum Sampling was carried out monthly is composed of fine sand and partly from February to June, 2016. The covered with fallen leaves and logs of samples were collected from three wood. It is fast flowing and water is stations (Stations 1, 2 and 3) designated clear. Vegetation around this station along the course of the river and these includes Elaeis guineensis, Palisota stations were at least 100 meters apart hirsuta, Nymphea lotus . Human activities (Figure 1). Selection of the station was observed at this station include based on accessibility. Water samples processing food agricultural products, washing of cloths, bikes and dishes.
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Figure 1; Map showing sampling stations 1, 2 and 3 (yellow pins) at Obueyinomo River
Water Sample Collection and Periodicity bottles with glass stoppers. For DO, the The sampling stations where visited oxygen content of the water was each month from January 2016 to April immediately fixed by adding 1.5ml each 2016. Water samples for the of Winkler’s solutions A (Manganous determination of physical, chemical and sulphate) and B (Potassium hydroxide in biological studies were collected between Potassium iodide). The water samples for 9 am and 12 noon each sampling day. BOD were immediately wrapped in black Water and air temperature were polythylene bags and transported to the determined in situ using 0-100 oC laboratory. Surface water samples for the mercury in glass thermometer. Water determination of pH, conductivity, COD, samples for DO and BOD determination alkalinity, hardness, solids and major were collected using 250ml reagent ions were collected by immersing a 1
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Ethiopian Journal of Environmental Studies and Management Vol. 10 no.4 2017 liter plastic bottle 50cm below the water using SPSS 16.0 windows. Inter-station surface and allowing it to fill before comparisons were carried out to test for removing it from the water and were significant differences in the stored at 4°C and taken to the laboratory physiochemical conditions and the faunal for analysis. diversity using parametric analysis of Determination of Physical and variance (ANOVA). Duncan multiple Chemical Characteristics range (DMR) tests were further pH of the water sample was performed to determine the location of determined using the Griffin battery significant differences. Correlation operated pH meter (Hi-1992). The analysis was used to determine the conductivity of the water was measured relationship between the physicochemical using a HACH conductivity (Hanna 911) parameters. Principal component analysis meter by dipping the probe into the (PCA) was done to determine the sample. Total Solids, Total Dissolved distribution patterns of physicochemical Solids and Total Suspended solids were parameters in the studied stations. PCA determined gravimetrically as described was done using JMP statistical software in APHA, 1998. The turbidity of water v. 10 (SAS Institute). The principal (Nephelometric Turbidity Unit, NTU) components were extracted with was determined using the turbidity meter eigenvalues > 1 through varimax rotation. (Spectronic 2ID spectrophotometer) at Water Quality Index (WQI) room temperature. The dissolved oxygen Water Quality Index (WQI) is a very and biochemical oxygen demand was useful and efficient method which can determined using the Winkler’s method provide a simple characterisation of water APHA, (1998). Total alkalinity of the quality and it is based on some very water was determined by the titrimetric important parameters such as method described by APHA (1998). temperature, turbidity, TSS, TDS, pH, Chloride ion concentration was DO, BOD, nitrate, chloride, phosphate determined following by APHA (1998) and calcium. In this study, Water Quality and expressed in mg/L. Nitrate was Index (WQI) was calculated by using the determined by the colorimetric methods Weighted Arithmetic Index method as using phenoldisulphonic acid as described by (Cude, 2001). In this model, described in APHA, (1998) using the different water quality components are Milton Roy Spectronic 21D multiplied by weighting factor and are Spectrophotometer. Ascorbic acid then aggregated using simple arithmetic method (APHA, 1998) was used to mean. determine phosphate concentration using In assessing the quality of water in the Milton Roy Spectronic 21D this study, firstly, the quality rating scale Spectrophotometer to read the (Qi) for each parameter was calculated by absorbance. Calcium and Magnesium using the following equation; were determined titrimetrically following Qi = {[(V actual – V ideal) / (V standard APHA, 1998). – V ideal)] * 100} Statistical Analysis Where; Statistical analysis for central Qi = Quality rating of ith parameter tendency and dispersion were carried out for a total of n water quality parameters 509
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V actual = Actual value of the water Where, quality parameter obtained from Wi = Relative (unit) weight for nth laboratory analysis parameter V ideal = Ideal value of that water Si= Standard permissible value for quality parameter can be obtained from nth parameter the standard Tables. 1= Proportionality constant. V ideal for pH = 7 and for other Finally, the overall WQI was calculated parameters it is equalling to zero, but for by aggregating the quality rating with the DO V ideal = 14.6 mg/L unit weight linearly by using the V standard = Recommended Federal following equation: Ministry of Environment permissible WQI = Σ WiQi/ Σ Wi limits standard of the water quality Where, parameter. Qi = Quality rating Then, after calculating the quality Wi = Relative weight rating scale (Qi), the Relative (unit) weight (Wi) was calculated by a value In general, WQI is defined for a inversely proportional to the specific and intended use of water. In this recommended standard (Si) for the study the WQI was considered for human corresponding parameter using the consumption and the maximum following expression;\ permissible WQI for the drinking water Wi = 1/ Si was taken as 100 score (Table 1).
Table 1: Grades Water Quality Index and status of water quality Water Quality Index Levels Description < 50 Excellent 50 - 100 Good 100 - 200 Poor 200 - 300 Very poor (bad) water > 300 Unsuitable (unfit)for drinking
Results and Discussion presented in table 2. The table shows the Physicochemical Parameters mean, standard deviation, minimum and The summary of the physical and maximum values for each parameter chemical parameters of the study stations analysed for the different stations. along a stretch of Obueyinomo River are
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Table 2: Summary of the physical and chemical characteristics of water at the designated stations along a stretch of Obueyinomo River Station 1 Station 2 Station 3 Parameter ±SD ±SD ±SD p-Value NIS Water Temp. (°C) 26.18±0.93 26.04±0.94 25.38±0.84 p>0.05 35.00 (25.00-27.00) (25.00-27.30) (24.80-26.80) TDS 19.43±16.67 9.89±6.68 7.42±2.90 p>0.05 500.00 (5.30-42.40) (5.30-21.20) (5.30-10.60) TSS 4.93±2.84 5.40±3.77 9.73±3.21 p>0.05 <10.00 (0.67-8.00) (2.33-11.67) (7.00-15.00) TS 23.70±15.04 15.29±10.40 17.15±5.04 p>0.05 (11.73-46.07) (7.63-32.87) (12.63-25.60) Turbidity 8.67±5.65 12.07±9.41 16.33±6.06 p>0.05 5.00 (0.33-15.33) (2.00-27.00) (9.00-25.33) pH 6.31±0.45 6.12±0.60 6.21±0.40 p>0.05 6.50-8.50 (5.60-6.73) (5.17-6.73) (5.73-6.67) Conductivity 36.67±31.45 18.67±12.61 14.00±5.48 p>0.05 (10.00-80.00) (10.00-40.00) (10.00-20.00) Hardness 9.33±3.13 11.33±4.88 10.27±2.39 p>0.05 (6.00-14.00) (6.00-19.33) (6.67-13.33) Alkalinity 9.87±2.38 11.60±3.00 16.13±12.80 p>0.05 (6.67-12.00) (8.00-15.33) (6.67-38.67) DO 4.27 a ±0.88 2.82 b ±1.25 2.04 b ±0.93 P<0.05 7.50 (3.37-5.43) (1.90-4.83) (1.23-3.47) BOD 1.76±0.73 1.23±0.63 1.93±0.99 p>0.05 (0.57-2.53) (0.77-2.30) (0.87-3.23) Chloride 13.17±2.12 14.11±1.66 14.58±3.87 p>0.05 (11.72-16.50) (11.78-16.47) (11.77-21.18) Nitrate 1.44±1.47 1.01±0.68 0.96±0.64 p>0.05 200.00 (0.16-3.80) (0.29-1.90) (0.36-1.63) Phosphate 0.48±0.66 0.56±0.85 0.50±0.69 p>0.05 (0.06-1.64) (0.05-2.08) (0.04-1.73) Calcium 1.81±0.40 2.03±0.82 1.92±0.44 p>0.05 5.00 (1.33-2.40) (1.07-3.21) (1.33-2.40) Magnesium 1.17±0.60 1.52±0.84 1.33±0.58 p>0.05 (0.49-1.95) (0.49-2.76) (0.49-1.94) All units are in mg/L except otherwise mentioned p>0.05 – No Significant Difference; p<0.05 – Significant Difference Similar Superscripts in a row – No Significant Difference NIS: Nigerian Industrial Standards
Mean ambient temperatures were respectively. From the study, the 30.14±1.28, 29.80±1.19 and temperature of the water across the 29.46±1.73°C in stations 1, 2 and 3 stations were within the stipulated limit respectively. Mean water temperatures of 35 oC by Federal Ministry of were 26.18±0.93, 26.04±0.94 and Environment (FMEnv). Similar values of 25.38±0.84°C in stations 1, 2 and 3 water temperature were obtained by 511
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Ekhaise and Anyasi (2005) at turbidity could be attributed to the unperturbed portion of Ikpoba River. The presence of decaying organic matter. The water temperature values obtained in this turbidity levels obtained in this study study were slightly lower than what was were lower than the range of 21.00 to obtained by Dimowo (2013) in the 29.40 NTU obtained by Rim-Rukeh et al . assessment of physico-chemical (2006) on the effects of Agricultural parameters of River Ogun. The mean Activities on the Water Quality of values of total dissolved solids were Orogodo River, Agbor Nigeria. Mean 19.43, 9.89 and 7.42 in stations 1, 2 and 3 values for pH were 6.31±0.45, 6.12±0.60 respectively. The mean values for total and 6.21±0.40 respectively. The slightly suspended solids were 4.93 mg/L, 5.40 acidic condition of Obueyinomo River is mg/L and 9.73 mg/L in stations 1, 2 and typical of the tropical aquatic bodies. 3 respectively. The mean values for total Reference had earlier been made on this solids were 23.70±15.04, 15.29±10.40 condition by Ogbeibu and Anagboso and mg/l at stations 1, 2 and 3 (2003) in their study of physicochemical respectively. The mean levels of total characteristics of Uto River. At average, dissolved solids and suspended solids the pH values across the stations did not across the stations in this study were in comply with FMENv. stipulated values consonance the stipulated values by of 6.50 – 8.50 for surface water. FMENv standards for surface water. TDS According to Rim-Rukeh et al . (2006) concentrations in this water body acidic conditions in an aquatic body is exhibited significant and positive attributable to humic acid formed from correlations with the conductivity and decaying organic matter. pH exhibited a phosphate concentrations in the water. positive and significant correlation with These relationships indicate that the nitrate concentration. This may have dissolved solids in this water body was resulted from the fact that the dissolution mainly constituted by ions. The levels of nitrogenous compounds in the water total dissolved and suspended solids associates strongly with water pH . For recorded in this study were lower when electrical conductivity, the highest value compared to the range of 64.21 – 320.06 (80.00µS/cm) was recorded in station 1 mg/L and 11.29 – 36.01 mg/L while the lowest value (10.00 µS/cm) respectively as documented by Duru and was recorded at all stations in different Nwanekwu (2012) in their study of time intervals. The mean values for physicochemical and microbial status of electrical conductivity were 36.67±31.45, Nworie River, Owerri, Imo State, 18.67±12.61 and 14.00±5.48 µS/cm in Nigeria. The variations can be attributed stations 1, 2 and 3 respectively. to spatial and temporal differences. Conductivity is a function of ions in Mean values for turbidity were water sample (Chinedu et al ., 2011). The 8.67±5.65, 12.07±9.41 and 16.33±6.06 conductivity values obtained in this study NTU in stations 1, 2 and 3 respectively. were low when compared to the range of The turbidity levels across all the stations 102.90 – 513.08 µS/cm obtained by Duru did not comply favourably with FMENv. and Nwanekwu (2012) in their study of stipulated value of 5.00 NTU for surface physicochemical and microbial status of water. These relatively high levels of
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Nworie River, Owerri, Imo State, documented by Olorode et al . (2015) in Nigeria. Imo River. The highest mean value of Mean values for hardness were BOD (1.93 mg/L) was obtained in station 9.33±3.13, 11.33±4.88 and 10.27±2.39 3 while the lowest value (1.23 mg/L) was mg/l in stations 1, 2 and 3 respectively. obtained in station 2. Mean values for Chemically, hardness is often defined as BOD were 1.76±0.73, 1.23±0.63 and the sum of polyvalent cation 1.93±0.99 in stations 1, 2 and 3. The concentrations dissolved in water values of BOD at the three stations (Wilson, 2010). In fresh waters, the showed no significant difference principal hardness-causing ions are (p>0.05). Other indirect laboratory test Calcium and Magnesium. Strontium, for assessing the DO is the BOD which is Iron, Barium and Manganese ions also the amount of oxygen required to contribute (USEPA, 1976). The levels of biologically break down a contaminant hardness across the stations were not (Ugwu and Wakawa, 2012). BOD significantly different from one another . therefore is an important parameter of Mean values for alkalinity across the water indicating the health scenario of stations were 9.87±2.38, 11.60±3.00 and freshwater bodies (Bhatti and Latif, 16.13±12.80 mg/l in stations 1, 2 and 3. 2011). The BOD values obtained in this The alkalinity values obtained in this study were low when compared to the study were relatively low when compared range of 9.55 - 13.21 mg/L obtained by to the range of 20.00 – 32.00 mg/L Ugwu and Wakawa (2012). The highest obtained by Ahiarakwem and Onyekuru value (21.18 mg/L) for chloride was (2011) in their comparative assessment of recorded in station 3 while the lowest the physico-chemical and microbial value (11.72 mg/L) was recorded in trends in Njaba River, Southeastern station 1. The mean values for chloride Nigeria. The difference can be attributed were 13.17±2.12, 14.11±1.66 and to variations that may have resulted from 14.58±3.87mg/l in stations 1, 2 and 3 alkalinity constituent as stated above respectively. The highest mean value of The mean values of DO were 4.27 nitrate (1.44 mg/L) was recorded at mg/L, 2.82 mg/L and 2.04 mg/L in station 1 and the lowest (0.96 mg/L) at stations 1, 2 and 3 respectively. The station 3. The nitrate concentrations in values for dissolved oxygen across the the water were 1.44±1.47, 1.01±0.68 and stations showed significant difference (p< 0.96±0.64mg/l in stations 1, 2 and 3 0.05) and Duncan multiple range test respectively. Mean values for phosphates indicated that this arose from station 1. were 0.48±0.66, 0.56±0.85 and 0.50±0.69 DO is the oxygen present in a dissolved mg/l in stations 1, 2 and 3 respectively. form in a water body (DWAF, 1993). It is Results from this study showed that one of the predictors of the ability of a chloride was dominant to other anions water body to hold aquatic life forms (nitrate and phosphate). Duru and (APHA, 2005). Dissolved oxygen levels Nwanekwu (2012) documented similar of Obueyinomo River were less than the variation in Nworie River. This is stipulated value of 7.50 mg/L by FMEnv contrary to the observation made by for surface water. Values similar to what Ugwu and Wakawa (2012) in which was recorded in this study were nitrate was recorded as the most
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Assessment of Water Quality of Obueyinomo River ...... ENUNEKU et al. dominant anion. This variation is conductivity, hardness, BOD, Chloride, attributable to anthropogenic activities Phosphate, Calcium and magnesium on-going at the watershed as nitrate showed no significant difference levels over 10 mg/L in natural waters (p>0.05). normally indicate man made pollution Test of Relationship amongst the (Ugwu and Wakawa, 2012). Nitrate and Physicochemical Parameters phosphate concentrations exhibited Correlation statistics was adopted in inverse and positive significant testing the relationship between the correlations with magnesium. Thus physicochemical parameters and the nitrate displaces magnesium and vice result is shown in table 3. An inverse and versa. The positive correlation between significant relationship was observed phosphate and magnesium is an between water temperature and pH (r=- indication that both probably are from the 0.679). The TDS levels in the water same source as evidenced in the PCA exhibited a positive and significant analysis where they formed a cluster. The relationship with conductivity (r=1.0000) highest mean value of calcium (2.03 and phosphate (r=0.552) while TSS mg/L) was recorded at station 2 and the exhibited the same pattern of lowest (1.81 mg/L) was at station 1. relationships with turbidity (r=0.785) and Mean values for calcium were 1.81±0.40, phosphate (r=0.618). TS showed positive 2.03±0.82 and 1.92±0.44mg/l in stations and significant relationships with 1, 2 and 3 respectively. Calcium recorded conductivity (r=0.938), hardness higher concentration than magnesium. A (r=0.613 ), phosphate (r=0.748), calcium similar trend was documented by Agu et (r=0.539) and magnesium (r=0.522) al. (2014) in Obinna River. This order is concentrations in the water. An inverse consistent with the common trend relationship was observed between observed in Nigerian inland freshwaters hardness and nitrate while the former in which calcium and magnesium are the showed positive correlation with most important cations. The phosphate, calcium and magnesium. concentration of calcium across the Distribution Patterns of stations were low when compared to the Physicochemical Parameters in the range of 9.26–19.24 mg/L obtained by Study Areas Anyanwu (2012) in his study of physico- Figure 2 shows distribution patterns chemical and some trace metal analysis of physicochemical parameters in stations of Ogba River, Benin City, Nigeria. 1, 2 and 3 was analysed using principal Calcium levels of Obueyinomo River component analysis (PCA). Component 1 compared favourably with the stipulated made up 36.4% of the PCA while value of 5.00 mg/L by FMEnv for surface component 2 made up 21.7%. There was water. Mean values for magnesium were a strong association between stations 1, 2 1.17±0.60, 1.52±0.84 and 1.33±0.58mg/l and 3 (clustered on one side) which was in stations 1, 2 and 3 respectively. Across also highly associated with nitrates. stations, mean values for ambient Hardness, magnesium calcium and temperature, water temperature, total phosphate formed a cluster showing the dissolved solids, total suspended solids, contributions of these ions to water total solids, turbidity, electrical hardness. Alkalinity, suspended solids 514
Ethiopian Journal of Environmental Studies and Management Vol. 10 no.4 2017 and chloride formed a cluster suggesting total dissolved solids clustered on one that the suspended solids are largely side showing a relationship between composed of chlorides. Conductivity and conductivity and total dissolved solids.
Figure 2: Distribution patterns of physicochemical parameters in stations 1, 2 and 3 characterised by PCA: +station 1; *station 2; o station 3. DO: Dissolved oxygen; BOD: Biochemical Oxygen Demand; Hard: Hardness; Mg: Magnesium; Ca: Calcium, Ph: Phosphorus; AL: Aluminium; SS: Suspended solids; Chl: Chloride; AT: Air Temperature; WT: Water Temperature; Nit: Nitrates
Assessment of the Water Quality (WQI) water quality across the stations. Figure 3 The water quality of Obueyinomo shows the contribution of the various River was assessed using water quality parameters to the overall variation in the index. Table 3 shows the summary of the WQI values across the stations.
Table 3: Summary of the Water Quality Index across the Stations Station 1 Station 2 Station 3 Benchmark WQI 138.45 122.70 170.01 100.00
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Fig. 3: Spatial Variations in the Quality Rating
Water quality index (WQI) in was Conclusions adopted in the assessing the water quality The physicochemical characteristics and health status of Obueyinomo River. of a stretch of Obueyinomo River were Water quality index (WQI) is a means to assessed in this study to determine their compressing large amounts of water spatial and temporal variability and quality data into simple terms (e.g., further ascertain its quality and suitability excellent, good, poor etc.) for reporting to for human consumption. With the Environmental Managers and the public exception of turbidity, pH, BOD and DO, in a consistent manner (Ashwani, and the other physicochemical parameters Anish, 2009). WQI values revealed that if were within Federal Ministry of the water obtained from this water body Environment standard for surface water. is not treated by physical or chemical This study further revealed that the water methods, it would be unsuitable for samples from this river should be treated drinking. This is because the aggregated before consumption by human since the values at various stations exceeded the estimated WQI was above 100. maximum permissible WQI for human consumption which according to Ahmad References et al. (2012) was taken as 100 score. The Agu, C.C., Menkiti, M.C., Okolo, B.I. parameters responsible for the high and Nnaji, P.C. (2014). Evaluation values of WQI as revealed by quality of the level and impact of selected rating include turbidity, pH, dissolved physiochemical parameters of oxygen and biochemical oxygen demand. fertilizer effluent on Obinna River, The concentrations of these parameters Adani, Enugu State, Nigeria. also exceeded the stipulated values by Journal of Water Resource and FMEnv. for surface water bechmarks. Protection , 6: 722-730.
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