Water quality of sample water from wells

Hydrogeology

1. UNIVERSITY OF DAR ES SALAAM SCHOOL OF MINES AND GEOSCIENCES(SoMG) DEPARTMENT OF GEOSCIENCES GY 405: INDEPENDENT PROJECT PRESENTER: ELIAIKA G. MMARI REGISTRATION 2020-04-07428 SUPERVISOR: Mr. MREMI WILLIAM A

2. STUDY AREA Figure 1: A map of Dar es salaam showing the study area

3. REGIONAL GEOLOGY Quaternary deposits-sediments fills the ancient valley, they eroded from Neogene deposits of clay bound sand. Quaternary deposits subdivided into Alluvial deposits, marine deposits and sand Neogene deposits grouped into mio-pleistocene and lower Miocene. Mio pleistocene are clay bound sand and gravel extend towards northwest,southeast and to south. Lower Miocene consists of Pugu kaolinitic sandstone in western part of DSM. Also minor siltstone, shale and limestone.

4. HYDROGEOLOGY Quaternary deposits of sand, gravel and silts are main and primary aquifer in DSM . They are permeable and porous enough to store and transmit groundwater. Quaternary aquifers have confined and unconfined aquifers separated by aquitard of clay deposit. Mio-pleocene sediments form deeper aquifer. They dominated by clay at the top and clay decrease downward. Pugu hill consists fractured and weathered older rock which are less permeable. Coastal aquifers are recharged directly by rainfall. There are seasonal streams ie Mpiji, Tegeta, Mbezi Mlakuwa, Nyakasangwe, Kijiyonyama and Sinza. The seaward nature of Coastalplain strata allow water to flow from higher elevated areas ,Pugu hill towards coastal areas.

5. STATEMENT OF THE RESEARCH PROBLEM Most boreholes in Kinondoni municipal have depth range between 40-60meters from the surface. Boreholes drilled near the ocean ie Osterbay, Masaki, Mbweni, Bahari beach and Kawe have depth range between 10-20meters. Since shallow aquifers are the main source of water in Kinondoni,they are easily polluted by surface and subsurface sources. Few research have been done on assessment of microbial contamination, heavy metals contamination, seawater intrusion and hydrogeological characterization. These research were limited on understanding the interaction between groundwater and subsurface as well as targeting point source and non point source of pollution in Kinondoni aquifers. This study focused on evaluation of groundwater quality and possible sources of pollution in Kinondoni aquifers.

6. OBJECTIVES MAIN OBJECTIVE To asses the quality of groundwater and sources of pollution in Kinondoni aquifers. SPECIFIC OBJECTIVES To assess physical and chemical parameters of groundwater. To determine type and evolution/origin of Kinondoni groundwater. To determine sources and level of groundwater pollution in Kinondoni aquifers. To identify possible measures for protection of groundwater at Kinondoni.

7. RESEARCH QUESTIONS Do water quality parameters meet standard limit? What is the geologic nature of the study area? What anthropogenic activities take place in the study area? What causes the observed parameters

8. SIGNIFICANCE OF STUDY The results will help to understand extent and trend of ground water pollution in Kinondoni aquifers. Also, the result will signify possible factors/sources influencing chemical composition in area hence need for management and sustainability of ground water. Also the study will recommend the management and remediation methods

9. METHODOLOGY Sample collection Twenty seven samples were collected from different boreholes in study area to represent urban and periurban areas. One litre of water sampling bottles was labeled according to sites and coordinates. Sample analysis EC, pH and TDS measured on site by portable EC meter , alkalinity, total hardness and total calcium obtained by titration method in the laboratory. Data analysis Data obtained from the laboratory were analyzed using MS excel spreadsheets. The results were assessed by comparing them with Tanzania drinking water standard limits of 2008.

10. Statistical analysis Descriptive analysis was used to describe parameter variations of water quality data in different sites. Correlation analysis was used to establish relationship between parameters. Water classification Piper trilinear diagram was used to further reveal hydro chemical facies, the water type in the area and its origin. Hydro chemical facies from piper plots were used to deduce the hydrogeologic processes taking place and it's influence on composition of groundwater.

11. Figure 2: The map showing sampling sites in Kinondoni area SAMPLING SITES

12. Table 1: The physicochemical parameter results of the water samples. LOCATION PARAMETERS Locality Northings Eastings Ph EC TDS TH Ca2+ Mg2+ Na1+ So42- HCO- CL1- TBS Standard     6.5-9.2 2000 1000 600 300 100   600   800 Bahari Beach 9264591 522060 7.21 12070 6638.5 2875 780 224.96 1453.73 2332.46 2332.46 1863.75 Mbweni 9270065 516826 6.9 7760 4268 2125 550 182.4 817.92 1521.55 1521.55 1420 Wazo 9264787 514949 7.25 2490 2370 875 320 18.24 170.06 726.62 726.62 195.25 Tegeta 9255398 514597 7.4 2060 1030 875 90 145.92 94.25 353.76 353.76 266.25 Mikocheni 9253967 525795 7.2 5290 2909.5 1750 560 85.12 411.76 911.856 911.856 962.05 Mabwe Pande 9265327 510297 7.5 2540 1397 787.5 280 21.28 221.73 662.5 662.5 266.5 Bunju 9270789 511736 7.2 3440 1720 1100 400 24.3 285.13 535.7 535.7 621.2 Kijito Nyama 9250169 525728 7.4 5220 1171.5 1900 550 127.6 323.00 426.5 426.5 1187.5 Ununio 9266139 520617 7.4 5070 2535 1000 200 121.6 706.02 630.2 630.2 781 Madale 9261890 514763 6.8 2530 1265 1325 240 176.32 27.58 721.44 721.44 248.5 Masaki 9216690 493297 8 27500 13750 3750 490 614 4599.35 5944.8 5944.8 7011.2 Mbweni 9271698 517438 7.3 6620 3310 1300 480 24.3 924.42 984.9 984.9 1491 Kwembe 9246927 508591 7.4 5430 3261.5 1612.5 395 152 506.51 998.4 998.4 1029.5 Sala Sala 9262241 519846 7.4 3190 1754.5 1125 315 82.08 215.73 645.6 645.6 510 RESULTS

13. LOCATION PARAMETERS Locality Northings Eastings Ph EC TDS TH Ca2+ Mg2+ Na1+ So42- HCO- CL1- TBS Standard     6.5-9.2 2000 1000 600 300 100   600   800 Mbezi Beach 9260433 525767 7.2 9320 4660 1250 340 104.57 1554.19 1479.84 1479.84 1952.5 Mbezi Luis- 9253359 513742 7.3 4160 2080 1187.5 365 121.6 307.00 696.48 696.48 816.5 Changanyikeni 9252412 522353 7.2 4810 2405 950 130 152 669.67 482.4 482.4 976.2 Goba 9257948 516144 7.5 3220 1771 1200 330 91.2 188.72 1031 1031 213 Osterybay 9253051 531084 7.45 16980 9230 4500 1480 194.56 1834.64 3877.63 3877.63 2840 B. Magengeni 9268443 515795 7.3 2480 1240 800 310 6.08 202.35 792 792 134.9 Tegeta A 9256183 515000 7.2 3160 1738 1100 340 60.8 219.67 648.48 648.48 497 Bunju 9268445 512646 7.35 3440 1720 1100 400 24.3 285.15 535.7 535.7 421.2 Osterybay 9253011 531084 7.2 3670 2018.5 1460 350 139.84 447.80 814.56 814.56 497 Sala Sala 9260300 518332 7.35 3440 1720 1100 400 24.3 285.13 535.7 535.7 621.2 Mbezi 9233394 510439 7.4 4200 2100 1057.5 321 62.016 479.23 792.48 792.48 514.75 MbeziMakabe 9252233 510079 7 2660 1463 750 120 109.44 269.87 792.48 792.48 213 Kibangu 9247658 521890 7 7560 4158 2025 510 182.4 807.98 4464.96 4464.96 1420 Cont..

14. CORRELATION OF VARIOUS CHEMICAL PARAMETERS The ratio of Ca: HCO3 shows that 17 samples from far away the ocean , 1:1 or nearly value. Seven samples from near the coastline show value greater than one. Three samples from far away the ocean show value less than 0.5. The ratio of Cl:HCO3 shows that near the ocean the ratio is much higher than the samples from distant areas. Chloride is higher near the ocean and decrease as the distance increase. Gibb's ratio; The ratio used to show mechanism for ground water contamination. It uses the ratio of one dominant cation to Na+ Ca and one dominant anion to Cl+ HCO3. The result close to one indicate evaporation dominance, the value close to 0.5 indicate rock water interaction and the value close to zero indicate calcite dissolution dominance. All samples from Kinondoni give result close to zero. The ratio of Na:Cl shows source of salinity in groundwater. The value close to one indicate sea water influence and the value greater than one indicate weathering of silicate bearing rocks, agricultural or industrial sources. Fifteen samples located near the ocean show value of 0.5-1, ten samples located distant from the ocean show value close to zero and two samples from distant location show the value greater than one.

15. Table 2: The ratio of various related parameters LOCATION Ca:HCO3 Na:Cl Ca/Ca+Na Cl/Cl+HCO3 Ca:Mg Cl/HCO3 Bahari Beach 1.566 0.78 0.027 0.051 3.467 3.742 Mbweni 1.528 0.576 0.019 0.039 3.015 3.945 Wazo 1.230 0.871 0.111 0.005 17.543 0.75 Tegeta 0.257 0.354 0.003 0.007 0.617 0.76 Mikocheni 1.349 0.428 0.019 0.027 6.579 2.318 MabwePande 1.12 0.832 0.009 0.007 13.158 1.066 Bunju 1.143 0.459 0.013 0.017 16.46 1.775 Kijitonyama 1.222 0.272 0.019 0.032 4.31 2.639 Ununio 0.222 0.904 0.007 0.021 1.645 1.736 Madale 1.2 0.111 0.008 0.07 1.361 1.242 Masaki 1.96 0.656 0.017 0.193 0.797 28.045 Mbweni 2.4 0.62 0.017 0.041 19.591 7.455 Kwembe 1.436 0.492 0.013 0.029 2.599 3.743 Sala Sala 1.26 0.423 0.01 0.014 3.838 1.133

16. LOCATION Ca:HCO3 Na:Cl Ca/Ca+Na Cl/Cl+HCO3 Ca:Mg Cl/HCO3 Mbezi Beach 0.756 0.796 0.012 0.054 2.251 4.339 Mbezi Luis 0.811 0.376 0.012 0.022 3.001 3.266 Changanyikeni 0.52 0.686 0.005 0.027 0.855 2.44 Goba 1.320 0.886 0.011 0.006 3.618 0.852 Osterybay 2.690 0.646 0.051 0.079 7.606 5.163 Boko Magengeni 1.27 1.5 0.01 0.004 50.989 0.487 Tegeta A 1.36 0.442 0.012 0.013 5.592 1.988 Bunju 1.142 0.677 0.013 0.011 16.46 1.42 Osterybay 1 0.901 0.012 0.013 2.502 1.203 Sala Sala 1.42 0.459 0.013 0.017 16.46 1.483 Mbezi 0.958 0.931 0.011 0.014 5.176 1.537 Mbezi Makabe 0.48 1.267 0.004 0.006 1.097 0.852 Kibangu 1.645 0.569 0.018 0.004 2.769 4.58 Cont.…

17. The ratio of Ca:Na shows that fourteen samples from distant location have higher value greater than one, then samples from areas near the ocean show low value and other samples show very low value. The ratio of Cl-(Na+K)/Cl used to show ion exchange between groundwater and aquifer. The positive value indicates disequilibrium of chloro-alkaline and negative value indicates equilibrium of chloro-alkaline indices. Most of samples near the ocean show positive value and minor samples rom distant location show negativ value. TDS / Cl shows the samples from near the ocean give positive result of higher value andthe samples collected far away frm ocean show variation of moderate to low value. Chloride type originating from evaporites (halites, calite and gypsum) dissolution.

18. Figure 4 shows the spatial distribution of concentration of TDS, EC and Total hardness. The concentration of EC and Total hardness is directly proportional to TDS in Kinondoni aquifer. SPATIAL DISTRIBUTION

19. WATER CLASSIFICATION AND HYDROCHEMICAL FACIES From piper plot major cation is calcium and major anion is chloride. Water type calcium chloride Hydro chemical facies characterizing the study area are Ca-Mg-Cl-HCO3 and Ca-Mg-Cl-HCO3-SO4.

20. CLASSIFICATION OF SALINE WATER According to Toddo and Mays 2005 classification based on TDS, there is no sample show value for fresh water type, twenty six samples fall within brackish water type and one sample from Masaki shows saline water type. There is no brine water type in Kinondoni aquifers. Type of saline water TDS( mg/l) Fresh 0-1000 Brackish 1000-10000 Saline 10000-100000 Brine Greater than 100000

21. INFLUENCE OF SEAWATER ON GROUNDWATER Toddo and Mays further classified the influence of seawater on ground water. One sample from Boko show there is no influence of seawater on ground water. samples from location far away the ocean show indicator of low influence of seawater. Eight samples fall within moderate saline water influence, six samples show high enough saline water influence, one sample from Mbweni show high saline water influence and one sample from Masaki shows very high saline water influence.

22. Table 4: Toddo and Mays classification on level of saline influence [Cl]:[HCO3] Level of saline water influence Less than 0.5 No saline water influence 0.5-1.5 Low saline water influence 1.51-3.0 Moderate saline water influence 3.01-6.5 High enough saline water influence 6.51-15.50 High saline water influence Greater than 15.50 Very high saline water influence

23. Driving factors Calcite dissolution (Driver JI 1997) Dissolution of calcite show the ratio of Ca:HCO3 is 1:1. Majority of samples fall within this value, calcite dissolves in ground water add significant amount of Calcium and bicarbonate. The abundance of carbonate will add significant amount of Ca and Mg. The Ca and HCO3 concentrations increase with Cl increasing are also likely result of carbonate dissolution. All samples give Gibb's ratio of close to one which provide evidence of calcite dissolution dominance. Evidence from piper plots Chloride concentration is higher than that of bicarbonate in locations close to ocean and calcium chloride type is caused by dissolution of calcite

24. THE INFLUENCE OF SEAWATER ON GROUND WATER/ SALTWATER INTRUSION Normal fresh groundwater in aquifer has high concentration of calcium and bicarbonate ions relative to other cations and anions. Seawater has high concentration of sodium and chlorine ions (reference) Since fresh water interact with seawater increases the concentration of sodium and chloride. The average ratio of Na:Cl is less than one indicating the source is presence of seawater mixing. Also, from piper plot calcium chloride water type found in marine interaction

25. Ion exchange The Ca concentration is much higher than Na due to cation exchange between groundwater and aquifer or rock i.e Clay. Clay releases Ca and take up Na and it can be proved by higher EC value. Higher EC is predominate the area with clay minerals. Also, chlo-alkaline indices show positive value which provide evidence for disequilibrium of chloro-alkaline especially in locations near the ocean. If cation exchange predominates the area then sum of equivalent major cations should be roughly constant along the flow path . However in Kinondoni aquifer the sum of cations is not constant indicating the cations change with calcite mineral dissolution and or seawater mixing.

26. Conclusion Most of studied sites in Kinondoni are contaminated with physical and chemical pollutants. The measured values of calcium, magnesium, chloride and sulphate ions are very high near the ocean contributing to the salinity and hardness . This level decrease as the distance from ocean increase. Other parameters such as heavy metals, pH, alkalinity, fluoride, orthophosphate and ammoniacal nitrogen are not problem. The geological formations and seawater mixing in the area is major cause for contamination of kinondoni aquifers. Anthropogenic activities contribute to sulfate concentration in water.

27. Recommendation The water softening and desalination must be practised during and after accessing groundwater in order to regulate hardness and salinity problem. There is a need for the implementation on strict laws and regulations on groundwater conservation to minimize pollution specifically for companies and industries. Also the boreholes owners should minimize the pumping rate especially in boreholes accessed near the ocean to minimize problem of salt water contamination. Public should be aware on safe waste disposal and encourage the use of organic fertilizer instead of chemicals. This study is limited to physiochemical parameters neglecting microbiological parameters and emerging pollutants which can also be the problem in the area. More research is encouraged to assess the long-term trends and seasonal variation of ground water quality in study area.