Quality Characteristics of water used for irrigation in urban and peri-urban agriculture in Greater Accra Region of Ghana: Health and Environmental Risk

Abstract

The environmental and health impact of urban and peri-urban irrigated agriculture in Ghana was assessed by analyzing irrigation water samples for both physico-chemical and microbiological characteristics. The measured data was used to evaluate comprehensive pollution index and sodium adsorption ratio. Water samples used for informal irrigation in urban and peri-urban agriculture in Ghana were found to contain significant levels of microbial load which is an indication of pollution. The total coliform levels ranged between 25 x 10² – 1209 x 10² cfu/100ml while that of E coli was 2 x10² – 651 10² cfu/100ml. The mean value for of the total coliform detected in the samples (517.917 x 10² cfu/100ml) far exceeded the recommended maximum allowable guideline value of 5000 cfu/100ml and 1000 cfu/100ml for irrigation water. The CPI values were found to vary in the range of 0.16 to 0.43 with an average CPI value 0.27 which is an indication of moderate pollution of the irrigation water. About 42% of samples were found to be sodic waters, hence there should be a degree of restriction on use of water from this area for irrigation. The sodium adsorption ratio SAR values recorded ranges between 3.42 and 24.75 indicating that almost all the irrigated water samples analysed had SAR values greater than 4 and the water has the potential to affect infiltration rate of water into the soil and permeability problems are expected for soils irrigated with water from the site. The irrigation water is stressed by persistent pollution load along its migratory pathway by expanding human activities in the study area and put the health of the environment, farmers, traders and consumers at high risks.