Abstract
Seasonal variations and trends of nitrates and phosphates concentration along the Boesmanspruit River in Mpumalanga Province.
By
Elelwani Constance Nethavhani
Student Number: 200831070
Minor Dissertation
Submitted to the Department of Geography, Environmental Management and Energy Studies
University of Johannesburg
In partial fulfilment of the requirements for the degree of Master of Science
In
Environmental Management
Supervisor: Professor I.T. Rampedi
Co-supervisor: Dr. F Sengani
Declaration
I hereby declare that this minor dissertation submitted to the Department of Geography, Environmental Management and Energy Studies within the Faculty of Science, University of Johannesburg for a Master of Science degree in Environmental Management is my own and original work. All sources used in the content of this minor dissertation have been acknowledged by means of references. I further declare that neither I nor anyone else has ever submitted this minor dissertation, in whole or in part to any institution of higher learning for a degree.
Elelwani Constance Nethavhani
Student Number: 200831070
Signature: _____________________ Date: 23 January 2023
Dedication
I am dedicating this study to my precious kids (Sibongumusa and Phiwokuhle Nkambule) who gave me purpose to strive for more and better things in life, and my beloved husband (Stuart Nkambule) who throughout this journey has been a continual source of support and inspiration.
This study is also dedicated to my parents (Mashudu and Johannes Nethavhani) for their unconditional love, support, and encouragement throughout my life, teaching me principles of life and working hard to acquire things I aspire to achieve. I would also like to dedicate this study to my siblings (Rofhiwa, Khathutshelo and Akonaho Nethavhani) whom I am truly grateful for having them in my life and for their support.
Acknowledgements
First and foremost, I want to thank the Almighty God for the gift of life, strength, knowledge and protection throughout.
I would like to sincerely acknowledge and thank Professor Isaac T. Rampedi and Dr. Fhatuwani Sengani for the supervision and guidance throughout this study.
Also, I want to thank my parents and my siblings (Mashudu, Johannes, Rofhiwa, Khathutshelo and Akonaho Nethavhani) for the love and support throughout my entire life.
My gratitude is expressed to my caring, loving and supportive aunt (Dorah Matsila) for always being there for me throughout.
Finally, my sincere appreciation to my Husband and kids for the encouragement and support when I deprived them of their time while completing this study.
Abstract
This dissertation investigated the seasonal variations and trends of nitrates and phosphates concentration along the Boesmanspruit River in Mpumalanga Province of South Africa. Analysis of nitrates and phosphates in water resources is of paramount importance in determining the health status of the resource and its possible impacts to receptors. The research only used secondary data which were obtained from the Inkomati - Usuthu Catchment Management Agency. The data entailed water quality results for nitrate, phosphate, and chlorophyll-a parameters for a period of five years (2017-2021). In analysing the data, nitrates and phosphates concentration were grouped into wet (October-March months) and dry (June-August months) seasons. Average nitrate and phosphate concentrations for the different seasons were calculated to determine their trends and they ranged between 0.1 – 0.2 and 0.13 – 0.24 respectively. These concentrations were also compared against the national water quality standards in terms of resource quality objectives and target water quality guideline thresholds. Chlorophyll-a concentrations for the Boesmanspruit and Nooitgedacht dams were 3.81 and 4.49 respectively and were used to determine the trophic status of the two dams associated with the Boesmanspruit River. The study findings are supported by previous studies that nitrate and phosphates concentration in water bodies fluctuates depending on the season. In general, the concentration of nitrates and phosphates were high during the wet season as compared to the dry season and there were more phosphates in the water resource compared to nitrates as phosphate concentrations in general were high compared to the nitrate concentrations. Run-off from cultivation as the predominating activity within the study area and discharge from the wastewater treatment works were identified as possible point and non-point sources of nutrient enrichment in the Boesmanspruit River. Monitoring point CRL-15 situated downstream of Carolina wastewater treatment works effluent discharge point was found to have more nitrates and phosphates concentrations as compared to other monitoring points. This is an indication of point-source contribution to high nitrate and phosphate concentration in the water resource. When compared to the national water quality standards, nitrates were compliant as they were below the regulated threshold whereas phosphate in most monitoring point did not comply as the concentrations were above the regulated thresholds, indicating that phosphate is the parameter of concern. The trophic status for both the Boesmanspruit and Nooitgedacht dams was oligotrophic, implying that the two dams are impacted by the enrichment of nutrients, but at a minimal level.
Key words: Chlorophyll-a, Eutrophication, Nitrate, Nutrients, Phosphate, Boesmanspruit.