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Bulletin of the Chemical Society of Ethiopia

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ANALYSIS OF NITRATES AND NITRITES IN SOME WATER AND FACTORY EFFLUENT SAMPLES FROM SOME CITIES IN SWAZILAND

A. O. Fadiran*, S. M. Mamba

Abstract


The levels of nitrates and nitrites in drinking water, river water and factory effluents from three major cities in Swaziland were determined by a pre-calibrated colorimetric method. The pooled mean concentration range for the nitrates in the river water samples is 1.74±0.13 – 115±3.27 mg/L as NO3–N and for nitrites is 1.50 ± 1.70 – 2.90 ± 2.77 mg/L as NO2–N. For the factory effluents, nitrate levels varied between 72.3 ± 6.81 mg/L and 75.7 ± 3.21 mg/L, giving a pooled mean of 74.0 ± 3.76 mg/L, while the concentration range for nitrites is 0.16 ± 0.02 – 0.21 ± 0.07 mg/L, giving a pooled mean of 0.18 ± 0.03 mg/L as NO2–N. Nitrate levels in the drinking water samples ranged between 0.70 ± 0.10 – 1.6 ± 0.07 mg/L, giving a pooled mean concentration of 1.3 ± 0.26 mg/L as NO3–N, while levels of the nitrites vary from 1.1 x 10-3 ± 1.2 x 10-4 – 7.93 x 10-3 ± 8.1 x 10-4 mg/L, yielding a pooled mean of 3.4 x 10-3 ± 3.0 x 10-4 mg/L as NO2–N. The observed mean as well as the highest single-point values for both nitrates and nitrites in drinking water are well below WHO\'s maximum acceptable concentration (MAC), of 10.0 mg/L nitrate as NO3–N and 3.0 mg/L nitrite as NO2–N. However, the levels of both species in the river water and factory effluents are high enough to necessitate the monitoring of their respective levels.



KEY WORDS: Leaching, Runoff, Methemoglobinemia, Nitrate fertilizer, Nitrogenous-waste, Water quality assessment


Bull. Chem. Soc. Ethiop. 2005, 19(1), 35-44.



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