Physicochemical properties of drinking water from selected sources in Khartoum locality

Abstract

This study was done to investigate the physical tests and the concentration of nitrite, nitrate and some heavy metals (iron, cadmium, copper, zinc and lead) in the three types of drinking waters (ground, surface and bottled water) consumed in Khartoum locality. Six locations of different drinking water sources (ground and surface) were selected for sample collection in addition to six samples of bottled water. Ground water samples were collected from Alkalahla Gotaaia block 3, Alkalakla Sangaat block1, Alazhari block 22, Alengaz block 1, Altayf south block 53, Alamarat street 41, and surface water samples were collected from Algaser Ganoob street, Naser block 6, Hai alsafa block1, Aldyom Alshargia block8, Hai Alsagana Algadid block 2 and Algoz block 6. The eighteen collected samples were subjected to physical and chemical examinations. The physical examinations were included the electrical conductivity, PH and turbidity, while the chemicals ones were total dissolved solid, nitrite, nitrate, iron, cadmium, copper, lead and zinc. The data collected were subjected to statistical analysis. The results were compared with international and national drinking water guidelines. They indicated that the turbidity level ranged from 0.30 to 11.30 NTU in groundwater and from 0.40 to 7.50 NTU in surface water, thus exceeding the permissible level of WHO (1993) standards (5 NTU). The range in bottled water was 0.10 to 0.50 NTU. The electric conductivity ranged from 185.30 to 686.00 µs/cm in groundwater, while in surface water it ranged from 184.40 to 208.00 µs/cm, and from 133.50 to 249.7 µs/cm in bottled water. The pH value in groundwater ranged between 7.63 and 8.020 in groundwater, while in sea water it ranged from 6.9 to 8.10, and from 7.50 to 8.20 in bottled water. The permissible level of WHO (1993) and SSMO (2002) pH standards is 6.5 – 8.5. The total dissolved solid ranged from 111.20 to 412.00 mg/l in groundwater, while in surface water the range was 110.60 – 125.30 mg/l, and 80.10 – 149.70 mg/l in bottled water. The permissible level of WHO (1993) and SSMO (2002) total dissolved solid standards is 1000 mg/l. The concentration of nitrite ranged from 0.04 to 0.30mg/l in groundwater, while four samples of surface water contained 0.04 mg/l, and two samples were free of nitrite. While bottled water nitrite concentration was in the range of 0.03 – 0.10 mg/l. The permissible level of WHO (1993) and SSMO (2002) nitrite standards is 10 mg/l and 2.0 – 10 mg/l, respectively. The concentration of nitrate ranged from 3.40 to 41.60 mg/l in groundwater, 2.42 to 3.96 mg/l in surface water samples, and 0.83 to 4.64 mg/l in bottled water. The permissible level of WHO (1993) and SSMO (2002) nitrate standards is 45–50 mg/l. The concentration of iron ranged between 0.16 and 0.30 mg/l in groundwater, and 0.16 to 0.40 mg/l in samples of surface water, exceeding the permissible level of WHO (1993) standard of 0.30 mg/l, it ranged from 0.13 to 0.18mg/l in bottled water. The concentration of cadmium ranged from 0.0001 to 0.0015 µg/l in groundwater, from 0.0001 to 0.0002 µg/l in samples of surface water, and 0.0002 µg/l in all samples of bottled water. The permissible level of WHO (1993) and SSMO (2002) cadmium standards is 0.005 and 0.003 mg/l, respectively. The concentration of copper ranged from 0.02 to 0.044 mg/l in groundwater, 0.029 to 0.037 mg/l in samples of surface water, and 0.058 to 0.085 mg/l in bottled water. The permissible level of WHO (1993) and SSMO (2002) copper standards is 2.0 and 1.5 mg/l, respectively. The concentration of lead ranged from 0.001 to 0.013 mg/l in groundwater, 0.007 to 0.012 mg/l in samples of surface water, thus exceeding the permissible level of WHO (1993) lead standards of 0.007 mg/l. And the lead content in bottled water was 0.004 – 0.005 mg/l. The concentration of zinc in all samples was zero mg/l. The permissible level of WHO (1993) and SSMO (2002) zinc standards is 3.5 and 3.0 mg/l, respectively It is concluded that most of the tap water samples and bottled water samples collected from Khartoum Locality are suitable for human consumption. A number of recommendations are suggested to improve the drinking water quality