Browsing by Author "Nkinda, Mihayo"

Now showing 1 - 4 of 4

Heavy metals risk assessment of water and sediments collected from selected river tributaries of the Mara River in Tanzania
(Springer Nature, 2021-06-25) Nkinda, Mihayo; Rwiza, Mwemezi; Ijumba, Jasper; Njau, Karoli
This study investigated the levels of Pb, Hg, Cr, Cd, and As in water and sediments from the tributaries of the Mara River, Tanzania. Pollution risk of water and sediments was investigated using seven indices and fve metals. During the dry period, the highest concentration of Pb, Hg, Cr, Cd, and As in sediments was 17.45 ±1.22, 0.01, 1.56±0.5, 1.3±0.09, and 30.81±0.02 mg/kg, respectively. During the wet period, the highest concentration of Pb, Hg, Cr, Cd, and As in sediments was 4.37±0.28, 0.012, 2.58±0.57, 2.25±0.35, and 53±0.02 mg/kg, respectively. For surface water, the respective highest concentrations of Pb, Hg, Cr, Cd, and As were 0.76±0.09, 0.04, 0.68±0.09, 0.74±0.1, and 0.47±0.06 mg/L for the dry period. The wet period max concentrations for Pb, Hg, Cr, Cd, and As in surface water were 0.56, 0.03, 0.55±0.03, 0.48±0.03, and 0.4±0.03 mg/L, respectively. Principal component analysis results indicated dominant loadings for Pb and As in sediments during the dry period. Comparison of sediment concentrations with sediment quality guidelines revealed that As and Cd were enriched. Correlation coefcient results indicated that As had a strong negative correlation with the rest of the elements in sediments during the dry period. In the wet period, As had a signifcant correlation with Cd (r=0.92, p<0.01) in sediments. The analysis of environmental risks indicated signifcant enrichment of sediments with As and Cd. It is important to put in place relevant control mechanisms targeting metals in the studied tributaries, with a focus on As and Cd.
Quantitative assessment of metal contamination and associated pollution risk in sediments from the Mara River in Tanzania
(Springer Nature Switzerland AG., 2020-10-21) Nkinda, Mihayo; Rwiza, Mwemezi; Ijumba, Jasper; Njau, Karoli
For most rivers in sub-Saharan Africa, information about pollution indices related to sediments is sparse. Sedimentological research of rivers that empty into Lake Victoria is highly patchy and wide apart. The present study determined the levels and associated risk of As, Cd, Cr, Hg, and Pb in sediments collected from four different sites along the Mara River that empties into Lake Victoria in Tanzania. Samples were collected in the dry and rainy months in 2019. Pollution indices, namely geo-accumulation index (Igeo), enrichment factor (EF), contamination factor (CF), modified contamination degree (mCd), pollution load index (PLI), potential ecological risk factor (Eri), and potential ecological risk index (RI) were used to evaluate the influence of heavy metal contamination in sediments. Dry month mean concentrations, in milligram per kilogram, of heavy metals were as follows: As (11.04 ± 0.13), Cr (1.02 ± 0.29), Cd (0.43 ± 0.05), and Hg (0.01) in the dry month. Respective sediment heavy metal concentrations for the rainy month were 22.22 ± 0.05 mg As/kg, 3.84 ± 0.34 mg Pb/kg, 1.53 ± 0.15 mg Cd/kg, 1.43 mg Cr/kg, and 0.03 mg Hg/kg. Generally, the risk indices showed high values in the rainy month and low values in the dry month, especially for As and Cd—an indication of anthropogenic influence. Correlation coefficient analysis for Pb and Cd showed a strong positive correlation (r = 0.99, p < 0.01)—this may suggest a similar source or similar transport behavior. Special attention needs to be paid with regard to rainy season As and Cd enrichment in the study area.
Risk assessment of heavy metals in water and sediments in the Mara river and its tributaries
(NM-AIST, 2022-07) Nkinda, Mihayo
The present study assessed the levels of As, Cd, Cr, Hg, and Pb in water and sediments from the Mara River and its tributaries in Tanzania. The Mara River has recently been exposed to anthropogenic activities including, mining, industrial, and farming activities, which are potential sources of heavy metals pollution. These emerging anthropogenic activities with a destructive impact on the environment motivated the author to conduct a risk assessment of heavy metals in the Mara River and its tributaries. In this endeavor, the author used indices, principal component analysis (PCA), and sediment quality guidelines (SQGs) tools to study the heavy metals pollution status in the area comprehensively. The study was conducted in the dry and rainy months of May and October 2019, respectively. Geochemical indices used in the present study were geo accumulation index (Igeo), enrichment factor (EF), contamination factor (CF), modified contamination degree (mCd), pollution load index (PLI), potential ecological risk factor (Er i ), and potential ecological risk index (RI). Moreover, the sediment quality guidelines (SQGs) were used for result comparisons. The principal component analysis (PCA) results indicated dominant loadings for As and Pb in sediments during the rainy month. Comparing sediment concentrations with sediment quality guidelines (SQGs) revealed that As and Cd may harm sediments-dwelling aquatic organisms. Correlation coefficient results indicated that As had a strong negative correlation with the other elements in sediments during the dry month. The analysis of environmental risk indices revealed significant enrichment of sediments with As and Cd. Contamination of As, Cd, and Pb along the Mara River was extremely severely enriched and linked to anthropogenic sources. Moreover, Cd and As in tributaries were elevated in the rainy month than in the dry months of 2019. As a result, enrichment factors of As, Cd, and Pb were extremely severely enriched. However, low contamination degree and very low pollution existed in water and sediments in the study area. Depending on rain and drought conditions, differentiated efforts are needed to minimize the effects of elemental loadings in the Mara basin ecosystem— with special attention for mitigation to be paid for As and Cd.
White Teeth and Healthy Skeletons for All: The Path to Universal Fluoride-Free DrinkingWater in Tanzania
(MDPI, 2019-01-12) Ndé-Tchoupé, Arnaud Igor; Tepong-Tsindé, Raoul; Lufingo, Mesia; Pembe-Ali, Zuleikha; Lugodisha, Innocent; Mureth, Risala Iddi; Nkinda, Mihayo; Marwa, Janeth; Gwenzi, Willis; Mwamila, Tulinave Burton; Rahman, Mohammad Azizur; Noubactep, Chicgoua; Njau, Karoli
Fluorosis has been prevalent in the great East African Rift Valley (EARV) since before this region was given a name. In the Tanganyika days, Germans reported elevated fluoride concentrations in natural waters. In the 1930s, the clear relationship between high fluoride level and mottling of teeth was established. Since then, the global research community has engaged in the battle to provide fluoride-free drinking water, and the battle is not yet won for low-income communities. An applicable concept for fluoride-free drinking water in the EARV was recently presented, using the Kilimanjaro as a rainwater harvesting park. The Kilimanjaro concept implies that rainwater is harvested, stored on the Kilimanjaro mountains, gravity-transported to the point of use, eventually blended with natural water and treated for distribution. This article provides a roadmap for the implementation of the Kilimanjaro concept in Tanzania. Specifically, the current paper addresses the following: (i) presents updated nationwide information on fluoride contaminated areas, (ii) discusses the quality and quantity of rainwater, and current rainwater harvesting practices in Tanzania, (iii) highlights how low-cost water filters based on Fe0/biochar can be integrating into rainwater harvesting (RWH) systems to provide clean drinking water, and (iv) discusses the need for strict regulation of RWH practices to optimize water collection and storage, while simplifying the water treatment chain, and recommends strict analytical monitoring of water quality and public education to sustain public health in the EARV. In summary, it is demonstrated that, by combining rainwater harvesting and low-cots water treatment methods, the Kilimanjaro concept has the potential to provide clean drinking water, and overcome fluorosis on a long-term basis. However, a detailed design process is required to determine: (i) institutional roles, and community contributions and participation, (ii) optimal location and sizing of conveyance and storage facilities to avoid excessive pumping costs, and (iii) project funding mechanisms, including prospects for government subsidy. By drawing attention to the Kilimanjaro concept, the article calls for African engineers and scientists to take the lead in translating this concept into reality for the benefit of public health, while simultaneously increasing their self-confidence to address other developmental challenges pervasive in Africa.