Assessment of Water Quality Parameters in the Bikolo Watershed, Tana Basin, Ethiopia

Horticulture is one of the thriving sectors in Ethiopia. However, it is also a risk for the environment due to the consumption of wide variety of chemicals and agricultural input that can affect different sources water quality. In addition to this Horticulture, use more water that can generate high amount of wastewater effluent. This study investigates the spatial and temporal variation of water quality along horticultural farm from Meshenti to Zegie Zuria watershed, Ethiopia. The effect of flower farm on ground and surface waters of tana watershed in Ethiopia was conducted during dry (January) and wet season (July) of 2017 based on physico-chemical and biological quality.11 water quality parameters from six sampling points were measured and analyzed. The results showed that GW (pH range 5.30 to 6.81) was slightly acidic (low pH) compared to SW (pH 7.32 to 10.67). GW turbidity ranged from 22.82 to 38 NTU whereas that of SW ranged from 15.82 to 87.45 NTU in both seasons. Chemical parameters measured in GW samples in this study were COD (ranging from 4.93 to 9.58mg/L) and BOD (1.35 to 4.20 mg/L) whereas SW COD and BOD ranged from 91.45to 129.33 mg/L and 3.52 to 27.53 mg/L respectively. TDS, DO, BOD, NO3 and PO4 showed significant difference (p<0.05) between the sampling points of spatial and temporal distribution of physico-chemical and biological.it can be conclude that the variations may come from the pollution of water quality by flower culture.

reported that in 2000 and 2004 Ethiopia was exported horticulture products from 20,734 to 28,592 metric ton.
The rapidly increasing demand for flowers, fruits, and vegetables in developed countries has made them best exportable commodities. The flower sector has only recently become an important agricultural sector for Ethiopia when regarding the export potential. It is a relatively new but at the same time very dynamic sector. Since 2001 up to 2007 the export value of flowers has increased from US$ 0.3 Million up to US$ 113 Million be a focus for potential foreign investors of many regions [5].
Horticultural activities, especially those conducted intensively without any physical obstacle to chemical leaching into the environment, can cause a threat to the quality of this state's water resources. Concerns include over-watering, excessive or poorly timed use of fertilizers or pesticides, inappropriate storage of chemicals and disposal of wastes that can leach contaminants.
There are around 121 chemicals that enter the country for the floriculture industry which are found on the world health organization negative pesticide list, while environmentalists have characterized some of these chemicals as having carcinogenic potential, such hazardous chemicals are used in the flower farming sector in Ethiopia.
Agricultural activities are a source of nutrients to both freshwater and marine ecosystems [6]the concentrations of which have been strongly correlated to the percentage of agricultural land in its catchment [7].Pesticide and fertilizer runoff are examples of diffuse nutrient sources from agricultural land use [8].Horticultural intensification has had great impacts upon the water quality of receiving water bodies [9]. As a result, many studies have tried to understand the controls on nutrients from such activities entering water stores.
Floriculture, or flower farming, is a discipline of horticulture concerned with the cultivation of flowering and ornamental plants for gardens and for floristry, comprising the floral industry.

Description of the Study Area
This study was conducted on the floriculture industry and the surrounding watershed from Meshenti to Zegie zuria where the industries are located, in Bahir Dar town. Meshenti which covers a total area of 425 hectares is located about 16kms from Bahir Dar town, Ethiopia on the road to Addis Ababa. The site was selected for horticulture site by the regional administration, considering its agro-climatic feature to the targeted project and its respective socioeconomic to the country. The climate of Meshenti is seasonal; winter (dry) months are hot and summer (rainy) months are cold.

Sampling and Laboratory analysis
During assessment of water quality in the Bikolo watershed, Tana basin concentration, eleven Physico-chemical and biological water quality parameters were analyzed from six sampling points in January and July 2017. Based on the site survey, a total of eleven water samples were collected from six sampling points along the greenhouses and watershed to assess the physicochemical, microbial and nutrients profile of the water. To observe the impact of the farm effluent on the water quality, samples were taken at six sampling sites such SS1, SS2, SS3 ,SS4, SS5 and SS6.Water samples were collected from Meshenti zuria Yinesa Sositu( Gogota, Achabir and Yinesa) and Zegie Zuria from six sampling points distributed alongside the flower farm using open water grab sampler 3L capacity prepared with a simple pull -ring that allowed for sampling at various water depths of borehole (20 -27m deep) for groundwater samples. The sampling sites were located by using ArcGIS 10.1 (Geographic Information System) and accurately marked on the map to indicate the spatial variations by using GPS coordinates ( Figure 2-1). The collected samples were kept in 1L polyethylene plastic bottles cleaned with metal-free soap, rinsed with de-ionized water and finally soaked in 10% nitric acid for 24 hr, finally rinsed with ultrapure water. All water samples were kept in an isolated cooler containing ice and delivered on the same to the laboratory and all samples were placed at a constant temperature 4 o C to avoid any contamination and the effects of light and temperature investigation [10]

Instruments and Equipment
The instruments used for this study are; multi parameter water quality checker (model: YSI pro 30) used to check sample water quality such as Temperature, DO, pH, TDS and turbidity once a time. Spectrophotometer (model: P/N 4930060) was used to measure nitrate and phosphate content present in the samples. Digital portable pH meter (model: Bante 901 -UK) was used for measuring of pH of the water sample. Turbid meter (model: TN100) was also used to suspended and colloidal particles measurement present in the sample.

Data Analysis
In the experimental study, the samples were taken from two factors (ground and surface water) at six sampling stations (SS1, SS2, SS3, SS4, SS5, and SS6) and three replications have made for each sample. To analyze this data Microsoft Excel (Microsoft Office 2007) and SPSS ANOVA software (Version 20) was used for the statistical data analysis.

RESULTS AND DISCUSSION
The physico-chemical analysis test analysis was conducted in Blue Nile water institute laboratory, water development bureau office water quality laboratory, Amhara Design and Supervision Works Enterprise water quality in Bahir Dar town, Ethiopia.
Journal of Environment and Earth Science www.iiste.org ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) Vol.10, No.1, 2020 The pH results for the water samples was ranged from 5.30 to 6.81 during dry season and from 5.30 to 6.35 during wet season , which was within the WHO allowable limit of 5.5 -7.5 for drinking water. The pH values within the range of 5.5 -7.5 were suitable for the normal range of irrigation [4].The pH of the Groundwater falls within FAO and WHO water quality guidelines for irrigation and drinking purposes. Turbidity Turbidity from table 3-1 above, maximum turbidity was recorded as 38.32 NTU during wet season and whereas 32.05 NTU in the dry season. During rainy season different dissolved particle such as silt, clay and other suspended particles contribute to the higher turbidity. The observed values of turbidity were above the WHO guide limit for both seasons in the study area.

Temperature
The temperature of water samples analyzed was a mean temperature value for all locations during the dry season (Table 3-1) was 33.09 ± 8.12°C, and the mean temperature during the wet season ( In study areas, total hardness (TH) values ranged from 112.63 ± 3.04mg/L to 296.85 ± 1.93mg/ L during the dry season and from 147.15 ± 5.12mg/L to 332.35 ± 4.88mg/L in wet season (Table 3-2), respectively. Total hardens content in al study areas was within the World Health Organization (WHO) hardness of water should be 500 mg/L for potable water, irrigation, agriculture and domestic uses.

BOD
The minimum value of BOD for the dry season was 1.51±1 mg/Land that of rainy season was 1.35±1.43 mg/L. Those values were above the permissible level of WHO drinking water standards of above 5mg/L.

COD
As shown in table 3-2, the mean COD content during dry season was 7.84 ± 0.33mg/L and then at of rainy season 5.66 ± 0.16mg/L.There was no WHO/EPA recommended value for COD for agriculture, aquatic life and domestic uses for groundwater.

Total Dissolved Solids (TDS)
The total dissolved solids (TDS) shows the degree of dissolved substances such as metal ions in the water. From the above table 3-2 the maximum value of TDS was 502.30 mg/L at dry season and 502.30 mg/L at the rainy season. The mean values of TDS for wet seasons were above the WHO permissible value while dry seasons are below the limit. concentrations in all the six sampling points in wet seasons and sampling points SS4, SS5 and SS6 in dry seasons were above the acceptable WHO guideline value of 50mg/L. Therefore, water from these study area was used for other domestic purposes such as for washing than drinking.

Phosphates
The concentration of phosphate in the water sampled from the sampling points ranged from 0.52 ± 0.05 to 1.78 ± 0.01mg/L in the dry season and 0.77 ± 0.02 to 2.50 ± 0.03mg/L in the rainy season (Table 3-3). The higher levels were observed in boreholes during the wet season in all sampling points and the least level was observed in dry Seasons. The concentration of PO4 3both in the dry and wet seasons in all sampling sites were above FEPA provisional standards (PO4 3-= 0.005mg/L). All the six sampling sites show that water in the study area exceeded WHO maximum allowable limit of 0.1 mg/L.

Spatial and Temporal Changes in Physicochemical Parameters in Surface Water
The results of the spatial and temporal variation in surface water physical parameters measured at all the six sampling sites over the study period are presented in table 3-4 below. ±0.50 ± 10.13 pH The observation of pH in surface water, sampling sites-2 (SS2) and SS4 had highest pH (10.67±0.52) and (10.17±0.64) respectively during wet season among all the study sites and the lowest pH (8.30±0.86) was found at site-5 (SS5). The pH values in dry season fluctuated from 7.32 ± 0.30 to 9.65 ± 0.50, whereas it varied from 8.30 ± 0.86 to 10.67 ± 0.52 in the wet season. A range of 6.5 -8.5 is suggested by WHO for surface water for drinking, domestic and agricultural purposes. The measured results at SS1, SS3, SS4, SS5 and SS6 during the dry season and SS5 in wet season were within the WHO guideline limit value for drinking, domestic, fishery and agricultural purposes. SS2 in the dry season and except SS5 all measured values in wet seasons were above WHO guideline value.
Journal of Environment and Earth Science www.iiste.org ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) Vol. 10, No.1, 2020 Turbidity Turbidity in Lake Tana nearby Zegie recorded ranges between 15.82 ± 14.30NTU to 87.45 ± 62.43NTU during the wet season. The maximum turbidity in water was recorded during wet season at SS6 (87.45 ± 62.43NTU). Turbidity in the studied area was within WHO guideline values of 5 -25 NTU during the dryseason. TDS From the data recorded table 3-4 the maximum total dissolved solids were observed during the wet season at the sampling site, SS4 (633.33 ± 321.21mg/L) than the dry season at sampling site, SS5 (565.45 ± 120.91mg/L). Almost all samples were observed within the limits 500 -1500 mg/L of WHO for drinking purpose, aquatic life and irrigation.

Temperature
The measured temperature of water sample ranges between 19.06 ± 8.10 to 21.81 ± 9.13 o C during the dry season, whereas it varied between the ranges of 17.51 ± 9.23 to 20.94 ± 10.12 o C during the rainy season. All water samples in this study had temperature values in the acceptable limit of WHO guidelines (less than 12-25 o C) for drinking, aquatic life, bathing, and irrigation purpose for surface water. The studied sites around flower farm and nearby watershed area show, low DO values in the dry season as compared to the wet season. The minimum dissolved oxygen (DO) was 1.36 mg/L during dry season whereas it was 1.67±0.03 mg/L in rainy season, which was below standard WHO.

Total hardness
The effect of dissolved minerals can be described by Total hardness Total (mostly Ca and Mg), it can also describe the suitability of water for different purpose recognized to the presence of bicarbonates, sulfates, chloride and nitrates of calcium and magnesium. Water with hardness in the range 0 -60 mg/L, 61 -120 mg/L, 121 -180 mg/L and > 180 mg/L are regarded as soft, moderately hard, hard and very hard, respectively. Surface water from the studied area recorded varying levels of total hardness between 293.45 ± 89.75 to 453.67 ± 113.12mg/L during dry season whereas it varied from 188.72 ± 93.47 to 407.75 ± 77.87mg/L in the wet season. Almost all the results show in the hard and very hard water range. The WHO report (2004a) recommends <500 mgCaCO3/L as the guideline value for surface water. In the studied area, generally be described as safe. BOD BOD determination is still the best available single test for assessing organic Pollution. The values of BOD at the studied sites ranged between 3.52 ± 0.05 to 4.20 ± 1.95mg/L during the dry season and 20.15 ± 0.08 to 27.53 ± 12.31mg/L during the wet season (Table 3 -5). The maximum amount of BOD in water sample was measured during the wet season at the sampling site, SS1 (27.53 ± 12.31 mg/L). The average concentrations of BOD in the studied area was 4.17 ± 0.02mg/L in the dry season and that of the wet season were 22.90 ± 4.12mg/L.BOD values in sampling sites SS1 (27.53 ± 12.31), SS3 (24.32 ± 0.06), SS4 (21.72 ± 4.03) and SS6 (23.45 ± 11.05mg/L) during wet season respectively were found to be above WHO desirable limit of 20 mg/L for irrigation, raw public water supply and aquatic life. However, BOD values in sampling sites SS2 (20.15 ± 0.08mg/L) and SS5 (20.25 ± 6.46mg/L) was found to be within the range of the guideline values. The results recorded during dry season were below WHO desirable limit of 5 mg/L for drinking use.

COD
The values of COD at the study sites was ranged between 91.45 ± 4.28 (control) to 125.54 ± 7.12mg/L (SS6) in dry season and 98.23 ± 1.52 (control) to 129.33 ± 10.23mg/L (SS6) during wet season (Table 3- Table 3-6 above surface water concentrations from the study area during dry season ranged from 2.55 ± 1.44 to 6.27 ± 3.38mg/L, whereas that of wet season varied from 3.45 ± 1.76 to 7.17 ± 2.71mg/L.There highest concentration of nitrate has been observed in sampling sites SS2 (6.82 ± 4.11mg/L), SS3 (5.44 ± 3.01mg/L) and SS5 (7.17 ± 2.71 mg/L) respectively during wet season due to evaporation, percolating NO3⁻ from sources such as decaying plant and animal materials, agricultural fertilizers and domestic sewage indicated that intensive use of fertilizer for flowers and crops were responsible for nitrate accumulation in surface waters. The minimum amount of nitrate in the water samples of the studied area was recorded during the dry season at SS1 (2.55±1.44mg/L), SS4 (3.16±1.69mg/L) and SS6 (3.12±1.87mg/L) respectively as compared with the wet season. According to WHO water quality guideline limit of 10 mg/L, the water in the studied area would be safe from polluting the existing water bodies in terms of nitrate.

Phosphates
The phosphate concentrations as PO4 3measured at six sampling sites over two sampling seasons were generally highest during the wet season, with an average of 3.04 ± 0.51mg/L and that of dry season were 2.22 ± 0.65mg/L (Table 3-6). The average PO4 3concentrations in both seasons were higher than the acceptable limit set by WHO prescribed limit of 0.1 mg/L for drinking water. The results of bacteriological analysis of boreholes in Meshenti to Zegie showed contamination with total coliform during dry as well as wet season for both ground and surface sources. The total coli form for the dry season ranged between 4.10 ± 0.01-to 4.95 ± 0.05MPN/100ml and that of the rainy season was ranged between 4.42 ± 0.08-to 6.00 ± 0.07MPN/100ml. As it can be seen in table 3-7, the bacterial colony counts were all above the WHO guideline limit of zero (0) MPN/100ml for drinking purposes.

CONCLUSIONS
Based on the data obtained from flower farm from Meshenti to Zegie Bikolo river watershed on water quality, temperature, pH, DO and BOD were within recommended limits at each sampling point during dry, wet seasons, while turbidity, TDS, nitrate, phosphate and total coliform exceeded recommended values at particular points in groundwater samples as well as in surface water. All bacteriological parameters analyzed were above guideline limit for drinking water. Results of one-way analysis of variance performed on the data related to pH, turbidity, TDS, DO, COD, and BOD suggested that all the measured parameters except temperature varied significantly among the sites (one-way ANOVA; p < 0.05).There were significant spatial and temporal variations (ANOVA; p <0.05) in the concentration of nitrates and phosphates in ground and surface water, with the wet season having highest levels in all sampling sites.
The spatial water quality analysis of individual parameters showed that almost all of them have acceptable ranges except for nutrients and total coliform concentrations. Highest concentration of phosphates was recorded in sampling site SS6 followed by SS5 during the rainy season while in the dry season the highest level was in site SS4. The concentration of NO3and PO4 3in all sampling sites were also beyond the FAO and WHO guideline values for maintenance of fisheries, aquatic life, and domestic use.
Generally, the deterioration in the quality of water could be accounted to rapid urban-industrialization activities, huge investment in horticulture production, increase in population with change of lifestyle, excess use of chemical fertilizers, pesticides in soil to meet the increasing demand in the market, destroyed the quality of ecologically rich watershed area.