Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo

Nicole Prisca Makaya Dangui Nieko; Jean de Dieu Nzila; Tarcisse Baloki Ngoulou; Emerson Maganga; Doria Moise Kaya-Ongoto; Faly Armel Soloka Mabika; Etienne Nguimbi

doi:doi:10.11648/j.ijema.20261401.11

Research Article |

Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo

Nicole Prisca Makaya Dangui Nieko^*, Jean de Dieu Nzila, Tarcisse Baloki Ngoulou, Emerson Maganga, Doria Moise Kaya-Ongoto, Faly Armel Soloka Mabika, Etienne Nguimbi

Published in International Journal of Environmental Monitoring and Analysis (Volume 14, Issue 1)

Received: 14 November 2025 Accepted: 11 December 2025 Published: 19 January 2026

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Abstract

Surface water quality in Dolisie (southwest of the Republic of Congo) is strongly impacted by human activities, particularly domestic wastewater discharge, agriculture, and livestock farming, leading to progressive degradation of water resources and posing risks to public health as well as domestic and agricultural uses. This study assessed water quality through analysis of physico-chemical and bacteriological parameters at several sites representative of domestic and agricultural areas. Physico-chemical analysis showed that pH ranged from 5.5 (Ninja Lake) to 9.9 (marsh near the Orthodox Church), with a mean of 6.58 ± 1.18. Water temperature varied from 25.36°C (upstream of the Loubomo River) to 28.5°C (Tahiti fish ponds), with an average of 26.83 ± 0.93°C. Electrical conductivity ranged from 115.66 to 315.33 µS/cm (mean 213.65 ± 73.18 µS/cm), while total dissolved solids (TDS) varied from 57 to 210.5 ppm (mean 112.52 ± 46.70 ppm). Three heavy metals were detected: cadmium (0.049–0.070 ppm, mean 0.057 ± 0.005 ppm), copper (0.0217–0.0509 ppm, mean 0.037 ± 0.010 ppm), and zinc (0.0004–0.00311 ppm, mean 0.004 ± 0.008 ppm). Microbiologically, total mesophilic aerobic flora (TMAF) ranged from 1,000 to 6,000 CFU/100mL (mean 3,333 ± 1,670), total coliforms from 69 to 193 CFU/100mL (mean 133 ± 43), and fecal coliforms from 32 to 102 CFU/100mL (mean 64 ± 21), exceeding WHO standards and indicating significant fecal contamination. Fecal streptococci ranged from 30 to 72 CFU/100mL, Staphylococcus spp. from 14 to 97 CFU/100mL, Salmonella from 40 to 110 CFU/100mL, Shigella from 19 to 77 CFU/100mL, and Pseudomonas aeruginosa from 15 to 62 CFU/100mL. Correlation analyses revealed significant relationships: temperature correlated with total coliforms (r = 0.69) and fecal coliforms (r = 0.63), electrical conductivity correlated with TDS (r = 0.91), and several bacterial groups showed positive correlations among themselves. Principal component analysis associated the F1 axis (42.24% of variance) with microbiological parameters and the F2 axis (20.7%) with physico-chemical parameters. These findings reveal progressive deterioration of surface water quality in Dolisie and emphasize the urgent need for sustainable management measures, public awareness, and wastewater control to preserve water resources and protect public health.

Published in	International Journal of Environmental Monitoring and Analysis (Volume 14, Issue 1)
DOI	10.11648/j.ijema.20261401.11
Page(s)	1-10
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

Surface Water, Physico-chemical Parameters and Bacteriological, Dolisie, Republic of Congo

References

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Nieko, N. P. M. D., Nzila, J. D. D., Ngoulou, T. B., Maganga, E., Kaya-Ongoto, D. M., et al. (2026). Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo. International Journal of Environmental Monitoring and Analysis, 14(1), 1-10. https://doi.org/10.11648/j.ijema.20261401.11

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ACS Style

Nieko, N. P. M. D.; Nzila, J. D. D.; Ngoulou, T. B.; Maganga, E.; Kaya-Ongoto, D. M., et al. Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo. Int. J. Environ. Monit. Anal. 2026, 14(1), 1-10. doi: 10.11648/j.ijema.20261401.11

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AMA Style

Nieko NPMD, Nzila JDD, Ngoulou TB, Maganga E, Kaya-Ongoto DM, et al. Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo. Int J Environ Monit Anal. 2026;14(1):1-10. doi: 10.11648/j.ijema.20261401.11

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@article{10.11648/j.ijema.20261401.11,
  author = {Nicole Prisca Makaya Dangui Nieko and Jean de Dieu Nzila and Tarcisse Baloki Ngoulou and Emerson Maganga and Doria Moise Kaya-Ongoto and Faly Armel Soloka Mabika and Etienne Nguimbi},
  title = {Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo},
  journal = {International Journal of Environmental Monitoring and Analysis},
  volume = {14},
  number = {1},
  pages = {1-10},
  doi = {10.11648/j.ijema.20261401.11},
  url = {https://doi.org/10.11648/j.ijema.20261401.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijema.20261401.11},
  abstract = {Surface water quality in Dolisie (southwest of the Republic of Congo) is strongly impacted by human activities, particularly domestic wastewater discharge, agriculture, and livestock farming, leading to progressive degradation of water resources and posing risks to public health as well as domestic and agricultural uses. This study assessed water quality through analysis of physico-chemical and bacteriological parameters at several sites representative of domestic and agricultural areas. Physico-chemical analysis showed that pH ranged from 5.5 (Ninja Lake) to 9.9 (marsh near the Orthodox Church), with a mean of 6.58 ± 1.18. Water temperature varied from 25.36°C (upstream of the Loubomo River) to 28.5°C (Tahiti fish ponds), with an average of 26.83 ± 0.93°C. Electrical conductivity ranged from 115.66 to 315.33 µS/cm (mean 213.65 ± 73.18 µS/cm), while total dissolved solids (TDS) varied from 57 to 210.5 ppm (mean 112.52 ± 46.70 ppm). Three heavy metals were detected: cadmium (0.049–0.070 ppm, mean 0.057 ± 0.005 ppm), copper (0.0217–0.0509 ppm, mean 0.037 ± 0.010 ppm), and zinc (0.0004–0.00311 ppm, mean 0.004 ± 0.008 ppm). Microbiologically, total mesophilic aerobic flora (TMAF) ranged from 1,000 to 6,000 CFU/100mL (mean 3,333 ± 1,670), total coliforms from 69 to 193 CFU/100mL (mean 133 ± 43), and fecal coliforms from 32 to 102 CFU/100mL (mean 64 ± 21), exceeding WHO standards and indicating significant fecal contamination. Fecal streptococci ranged from 30 to 72 CFU/100mL, Staphylococcus spp. from 14 to 97 CFU/100mL, Salmonella from 40 to 110 CFU/100mL, Shigella from 19 to 77 CFU/100mL, and Pseudomonas aeruginosa from 15 to 62 CFU/100mL. Correlation analyses revealed significant relationships: temperature correlated with total coliforms (r = 0.69) and fecal coliforms (r = 0.63), electrical conductivity correlated with TDS (r = 0.91), and several bacterial groups showed positive correlations among themselves. Principal component analysis associated the F1 axis (42.24% of variance) with microbiological parameters and the F2 axis (20.7%) with physico-chemical parameters. These findings reveal progressive deterioration of surface water quality in Dolisie and emphasize the urgent need for sustainable management measures, public awareness, and wastewater control to preserve water resources and protect public health.},
 year = {2026}
}

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TY  - JOUR
T1  - Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo
AU  - Nicole Prisca Makaya Dangui Nieko
AU  - Jean de Dieu Nzila
AU  - Tarcisse Baloki Ngoulou
AU  - Emerson Maganga
AU  - Doria Moise Kaya-Ongoto
AU  - Faly Armel Soloka Mabika
AU  - Etienne Nguimbi
Y1  - 2026/01/19
PY  - 2026
N1  - https://doi.org/10.11648/j.ijema.20261401.11
DO  - 10.11648/j.ijema.20261401.11
T2  - International Journal of Environmental Monitoring and Analysis
JF  - International Journal of Environmental Monitoring and Analysis
JO  - International Journal of Environmental Monitoring and Analysis
SP  - 1
EP  - 10
PB  - Science Publishing Group
SN  - 2328-7667
UR  - https://doi.org/10.11648/j.ijema.20261401.11
AB  - Surface water quality in Dolisie (southwest of the Republic of Congo) is strongly impacted by human activities, particularly domestic wastewater discharge, agriculture, and livestock farming, leading to progressive degradation of water resources and posing risks to public health as well as domestic and agricultural uses. This study assessed water quality through analysis of physico-chemical and bacteriological parameters at several sites representative of domestic and agricultural areas. Physico-chemical analysis showed that pH ranged from 5.5 (Ninja Lake) to 9.9 (marsh near the Orthodox Church), with a mean of 6.58 ± 1.18. Water temperature varied from 25.36°C (upstream of the Loubomo River) to 28.5°C (Tahiti fish ponds), with an average of 26.83 ± 0.93°C. Electrical conductivity ranged from 115.66 to 315.33 µS/cm (mean 213.65 ± 73.18 µS/cm), while total dissolved solids (TDS) varied from 57 to 210.5 ppm (mean 112.52 ± 46.70 ppm). Three heavy metals were detected: cadmium (0.049–0.070 ppm, mean 0.057 ± 0.005 ppm), copper (0.0217–0.0509 ppm, mean 0.037 ± 0.010 ppm), and zinc (0.0004–0.00311 ppm, mean 0.004 ± 0.008 ppm). Microbiologically, total mesophilic aerobic flora (TMAF) ranged from 1,000 to 6,000 CFU/100mL (mean 3,333 ± 1,670), total coliforms from 69 to 193 CFU/100mL (mean 133 ± 43), and fecal coliforms from 32 to 102 CFU/100mL (mean 64 ± 21), exceeding WHO standards and indicating significant fecal contamination. Fecal streptococci ranged from 30 to 72 CFU/100mL, Staphylococcus spp. from 14 to 97 CFU/100mL, Salmonella from 40 to 110 CFU/100mL, Shigella from 19 to 77 CFU/100mL, and Pseudomonas aeruginosa from 15 to 62 CFU/100mL. Correlation analyses revealed significant relationships: temperature correlated with total coliforms (r = 0.69) and fecal coliforms (r = 0.63), electrical conductivity correlated with TDS (r = 0.91), and several bacterial groups showed positive correlations among themselves. Principal component analysis associated the F1 axis (42.24% of variance) with microbiological parameters and the F2 axis (20.7%) with physico-chemical parameters. These findings reveal progressive deterioration of surface water quality in Dolisie and emphasize the urgent need for sustainable management measures, public awareness, and wastewater control to preserve water resources and protect public health.
VL  - 14
IS  - 1
ER  -

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Author Information

Nicole Prisca Makaya Dangui Nieko

Department of Live and Earth Sciences, Marien Ngouabi University, Brazzaville, Republic of the Congo.;Laboratory of Research in Geosciences and Environment, Brazzaville, Republic of the Congo

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Jean de Dieu Nzila

Laboratory of Research in Geosciences and Environment, Brazzaville, Republic of the Congo
Tarcisse Baloki Ngoulou

Department of Live and Earth Sciences, Marien Ngouabi University, Brazzaville, Republic of the Congo.;Laboratory of Research in Geosciences and Environment, Brazzaville, Republic of the Congo
Emerson Maganga

Department of Live and Earth Sciences, Marien Ngouabi University, Brazzaville, Republic of the Congo.
Doria Moise Kaya-Ongoto

Department of Cellular and Molecular, Marien Ngouabi University, Brazzaville, Republic of the Congo
Faly Armel Soloka Mabika

Department of Cellular and Molecular, Marien Ngouabi University, Brazzaville, Republic of the Congo
Etienne Nguimbi

Department of Cellular and Molecular, Marien Ngouabi University, Brazzaville, Republic of the Congo

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APA Style

Nieko, N. P. M. D., Nzila, J. D. D., Ngoulou, T. B., Maganga, E., Kaya-Ongoto, D. M., et al. (2026). Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo. International Journal of Environmental Monitoring and Analysis, 14(1), 1-10. https://doi.org/10.11648/j.ijema.20261401.11

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ACS Style

Nieko, N. P. M. D.; Nzila, J. D. D.; Ngoulou, T. B.; Maganga, E.; Kaya-Ongoto, D. M., et al. Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo. Int. J. Environ. Monit. Anal. 2026, 14(1), 1-10. doi: 10.11648/j.ijema.20261401.11

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AMA Style

Nieko NPMD, Nzila JDD, Ngoulou TB, Maganga E, Kaya-Ongoto DM, et al. Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo. Int J Environ Monit Anal. 2026;14(1):1-10. doi: 10.11648/j.ijema.20261401.11

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@article{10.11648/j.ijema.20261401.11,
  author = {Nicole Prisca Makaya Dangui Nieko and Jean de Dieu Nzila and Tarcisse Baloki Ngoulou and Emerson Maganga and Doria Moise Kaya-Ongoto and Faly Armel Soloka Mabika and Etienne Nguimbi},
  title = {Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo},
  journal = {International Journal of Environmental Monitoring and Analysis},
  volume = {14},
  number = {1},
  pages = {1-10},
  doi = {10.11648/j.ijema.20261401.11},
  url = {https://doi.org/10.11648/j.ijema.20261401.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijema.20261401.11},
  abstract = {Surface water quality in Dolisie (southwest of the Republic of Congo) is strongly impacted by human activities, particularly domestic wastewater discharge, agriculture, and livestock farming, leading to progressive degradation of water resources and posing risks to public health as well as domestic and agricultural uses. This study assessed water quality through analysis of physico-chemical and bacteriological parameters at several sites representative of domestic and agricultural areas. Physico-chemical analysis showed that pH ranged from 5.5 (Ninja Lake) to 9.9 (marsh near the Orthodox Church), with a mean of 6.58 ± 1.18. Water temperature varied from 25.36°C (upstream of the Loubomo River) to 28.5°C (Tahiti fish ponds), with an average of 26.83 ± 0.93°C. Electrical conductivity ranged from 115.66 to 315.33 µS/cm (mean 213.65 ± 73.18 µS/cm), while total dissolved solids (TDS) varied from 57 to 210.5 ppm (mean 112.52 ± 46.70 ppm). Three heavy metals were detected: cadmium (0.049–0.070 ppm, mean 0.057 ± 0.005 ppm), copper (0.0217–0.0509 ppm, mean 0.037 ± 0.010 ppm), and zinc (0.0004–0.00311 ppm, mean 0.004 ± 0.008 ppm). Microbiologically, total mesophilic aerobic flora (TMAF) ranged from 1,000 to 6,000 CFU/100mL (mean 3,333 ± 1,670), total coliforms from 69 to 193 CFU/100mL (mean 133 ± 43), and fecal coliforms from 32 to 102 CFU/100mL (mean 64 ± 21), exceeding WHO standards and indicating significant fecal contamination. Fecal streptococci ranged from 30 to 72 CFU/100mL, Staphylococcus spp. from 14 to 97 CFU/100mL, Salmonella from 40 to 110 CFU/100mL, Shigella from 19 to 77 CFU/100mL, and Pseudomonas aeruginosa from 15 to 62 CFU/100mL. Correlation analyses revealed significant relationships: temperature correlated with total coliforms (r = 0.69) and fecal coliforms (r = 0.63), electrical conductivity correlated with TDS (r = 0.91), and several bacterial groups showed positive correlations among themselves. Principal component analysis associated the F1 axis (42.24% of variance) with microbiological parameters and the F2 axis (20.7%) with physico-chemical parameters. These findings reveal progressive deterioration of surface water quality in Dolisie and emphasize the urgent need for sustainable management measures, public awareness, and wastewater control to preserve water resources and protect public health.},
 year = {2026}
}

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TY  - JOUR
T1  - Physico-chemical and Bacteriological Characterization of Surface Waters in the City of Dolisie, Republic of Congo
AU  - Nicole Prisca Makaya Dangui Nieko
AU  - Jean de Dieu Nzila
AU  - Tarcisse Baloki Ngoulou
AU  - Emerson Maganga
AU  - Doria Moise Kaya-Ongoto
AU  - Faly Armel Soloka Mabika
AU  - Etienne Nguimbi
Y1  - 2026/01/19
PY  - 2026
N1  - https://doi.org/10.11648/j.ijema.20261401.11
DO  - 10.11648/j.ijema.20261401.11
T2  - International Journal of Environmental Monitoring and Analysis
JF  - International Journal of Environmental Monitoring and Analysis
JO  - International Journal of Environmental Monitoring and Analysis
SP  - 1
EP  - 10
PB  - Science Publishing Group
SN  - 2328-7667
UR  - https://doi.org/10.11648/j.ijema.20261401.11
AB  - Surface water quality in Dolisie (southwest of the Republic of Congo) is strongly impacted by human activities, particularly domestic wastewater discharge, agriculture, and livestock farming, leading to progressive degradation of water resources and posing risks to public health as well as domestic and agricultural uses. This study assessed water quality through analysis of physico-chemical and bacteriological parameters at several sites representative of domestic and agricultural areas. Physico-chemical analysis showed that pH ranged from 5.5 (Ninja Lake) to 9.9 (marsh near the Orthodox Church), with a mean of 6.58 ± 1.18. Water temperature varied from 25.36°C (upstream of the Loubomo River) to 28.5°C (Tahiti fish ponds), with an average of 26.83 ± 0.93°C. Electrical conductivity ranged from 115.66 to 315.33 µS/cm (mean 213.65 ± 73.18 µS/cm), while total dissolved solids (TDS) varied from 57 to 210.5 ppm (mean 112.52 ± 46.70 ppm). Three heavy metals were detected: cadmium (0.049–0.070 ppm, mean 0.057 ± 0.005 ppm), copper (0.0217–0.0509 ppm, mean 0.037 ± 0.010 ppm), and zinc (0.0004–0.00311 ppm, mean 0.004 ± 0.008 ppm). Microbiologically, total mesophilic aerobic flora (TMAF) ranged from 1,000 to 6,000 CFU/100mL (mean 3,333 ± 1,670), total coliforms from 69 to 193 CFU/100mL (mean 133 ± 43), and fecal coliforms from 32 to 102 CFU/100mL (mean 64 ± 21), exceeding WHO standards and indicating significant fecal contamination. Fecal streptococci ranged from 30 to 72 CFU/100mL, Staphylococcus spp. from 14 to 97 CFU/100mL, Salmonella from 40 to 110 CFU/100mL, Shigella from 19 to 77 CFU/100mL, and Pseudomonas aeruginosa from 15 to 62 CFU/100mL. Correlation analyses revealed significant relationships: temperature correlated with total coliforms (r = 0.69) and fecal coliforms (r = 0.63), electrical conductivity correlated with TDS (r = 0.91), and several bacterial groups showed positive correlations among themselves. Principal component analysis associated the F1 axis (42.24% of variance) with microbiological parameters and the F2 axis (20.7%) with physico-chemical parameters. These findings reveal progressive deterioration of surface water quality in Dolisie and emphasize the urgent need for sustainable management measures, public awareness, and wastewater control to preserve water resources and protect public health.
VL  - 14
IS  - 1
ER  -

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