Nitrate and Nitrite Content of Well Water in Enugu, Southeast Nigeria

Abstract

Water samples from 20 artesian wells, chosen by the multistage sampling procedure from 5 zones in the city of Enugu, Southeast Nigeria, were analyzed by the disulfonic acid method in duplicate for the presence of nitrate (NO₃) and nitrite (NO₂). The zonal mean values for NO₃ were 0.45 mmol/l, 0.46 mmol/l, 0.55 mmol/l, 0.59 mmol/l, and 0.65 mmol/l (mean = 0.54 mmol/l), and for NO₂ the values were 0.34 mmol/l, 0.32 mmol/l, 0.21 mmol/l, 0.14 mmol/l, and 0.20 mmol/l (mean = 0.24 mmol/l), respectively. The mean values were reciprocally related (r = -.7356, p = 0.0002), indicating fecal contamination of well water. There were no significant differences between the mean values and the sum of the NO₃ and NO₂ values of the samples (p > 0.05), indicating uniform nitrogen content in the region. The mean value for NO₃ (0.54 mmol/l) was below the guideline values set by the World Health Organization, but the mean NO₂ concentration of 0.24 mmol/l was much higher (290%) than what is considered safe for humans.

Keywords:

• artesian wells
• disulfonic acid method
• nitrate
• nitrite
• Southeast Nigeria