Assessing the Occurrence of Heavy Metals in Edible Fruits Grown around Mine Tailings Dam in Kitwe

Mining activities in the Copperbelt province of Zambia have been of great environmental concern, despite recorded improvements in the socio-economic sector. Heavy metal contamination of soils resulting from depositing mine tailings and rock waste has posed possible health risks for communities nearer such facilities. The current study was conducted around residential homes surrounding Kitwe slimes (TD25). This work investigated levels of Co, Cu, Fe, Mn and Pb in the soils, and avocado and lemons fruits, growing near TD25. Heavy metals were analyzed using Atomic Absorption Spectrophotometer. The work further assessed the estimated daily intake (EDI) associated with potential health risks to humans. In the soil, concentration levels of heavy metals showed a trend in the order: Fe > Cu > Mn > Co > Pb. Heavy metal contents in avocado and lemon fruits at 200 and 400 m away from TD25, all had p-values < 0.05. The distances from the suspect source (TD25) to where the fruit trees were grown, had no influence on their concentration in the fruit samples. Fruit sample results showed that Fe had the highest EDI of 0.22 mg·kg-1 (avocado) and 0.14 mg·kg-1 (lemon), though both results were far below the FAO/WHO standard range (12.5 - 19.6 mg·kg-1). For both fruits, Co and Pb results were negligible. The concentration of the five heavy metals in avocado and lemon fruits grown around Kitwe slimes did not pose any health risks to the consumers.

Application of the Modified Adomian Decomposition Method on a Mathematical Model of COVID-19

In this study, we constructed and analysed a mathematical model of COVID-19 in order to comprehend the transmission dynamics of the disease. The reproduction number (RC) was calculated via the next generation matrix method. We also used the Lyaponuv method to show the global stability of both the disease free and endemic equilibrium points. The results showed that the disease-free equilibrium point is globally asymptotically stable if RC RC > 1. We further used the Adomian decomposition method and the modified Adomian decomposition method to obtain the solutions of the model. Numerical analysis of the model was done using Sagemath 9.0 software.

Short Term Leguminous Trees-Tillage Interactions and Their Effect on Soil-Water Content in a Semi-Arid Agroforestry Parkland

Agricultural activities that encourage slashing, burning and ploughing greatly affect the soil structure and soil organic matter on which soil water retention depends. In this study, we hypothesized that inclusion of rotational leguminous tree species improves soil water retention in a semi-arid conservation agriculture system. In a study done in Kibwezi, semi-arid eastern Kenya, results showed that the amount of water retained in the different soil strata from plots with different tree species and tillage practices was highly significant (P = 0.032). Plots with planting basins and Gliricidia sepium and Faidherbia albida tree species retained more water in both the upper and lower strata. Plots with G. sepium tree species under planting basins and zero tillage under F. albida had significantly higher soil organic carbon levels than plots that were managed under ridges and ploughing (P = 0.002). On the other hand, bulk density in plots with planting basins and zero tillage and ridges ranged between 1.35 g/cm3 and 1.53 g/cm3. Conventional tillage plots had bulk density values of 1.65 g/cm3 and 1.72 g/cm3 in the upper and lower strata respectively. The time-dependent nature of rotational leguminous tree species on soil organic matter and soil water retention in the semi-arid conservation agriculture system highlights the importance of considering these species for improving organic carbon and water retention for improved crop production.

Quantification of Heavy Metal Accumulation in Edible Wild-Mushrooms in Copperbelt and Western Provinces of Zambia

The mushrooms are highly regarded as one of the most nutritious foods across the globe but also recognized bio-accumulators of heavy metals. The nature and level of industrial activities are continually changing and affecting the environment adversely. The mushrooms are not an exception and may inevitably have heavy metal contaminations. In this vein, this study aimed to determine heavy metal (Cu, Ni, Co, Zn, Pb, and Cd) uptake levels in wild edible mushrooms from the sites with different economic activities. The wild mushrooms considered for this study included Tente (Amanita Zambiana), Ichikolowa (Termitomyces Titaniscus), and Kabansa (Lactarius Tataniscus). The analysis of heavy metal concentration was carried out using atomic absorption spectrometry (AAS). For the selected mushrooms, concentration ranges (mg&middot;kg-1 total dry weight (dw)) of 46.90 - 141.80 for Cu, 0.10 - 6.60 for Cd, 1.10 - 2.00 for Pb, 19.00 - 38.90 for Zn, 1.00 - 3.40 for Ni, and 44.80 - 79.70 for Co were obtained. However, for the respective soil samples, concentration ranges (mg&middot;kg-1&middot;dw) of 51.00 - 279.40 for Cu, 1.00 - 99.50 for Cd, 8.00 - 10.00 for Pb, 22.80 - 209.10 for Zn, 9.00 - 33.70 for Ni, and 60.00 - 111.90 for Co were obtained. To a certain degree, the concentrations reflected the impact of diversity in the surrounding activities. This study discovered that for the selected mushrooms, the contamination level of cadmium, cobalt, nickel, and copper exceeded the World Health Organization (WHO)/FAO (Food and Agriculture Organization) recommended limits. Although some minor aberrations from the prescribed limits were also observed in the case of copper and nickel. Further, the data established that the heavy metal concentrations in respective soils are not the sole determinant of concentrations in mushrooms. Thus, these findings merit attention as, in some cases, the extent of contamination has exceeded the WHO permissible limit, and it may pose a health risk to consumers.

Analysis of River Tributaries’ Streamflow Contribution Using WEAP Model: A Case of the Ngwerere and Kanakatampa Tributaries to the Chongwe River in Zambia

Ngwerere and Kanakatampa Streams are the main tributaries of the Chongwe River. The Ngwerere stream originates from the city of Lusaka and meanders through Lusaka City and Chongwe Town for an approximate distance of 41 km before joining into the upper part of Chongwe River. The Kanakatampa Stream is a tributary of the Chongwe River. It meanders from the Kanakatampa Area for approximately 52 km before discharging into the middle of the upper part of the Chongwe River. The Chongwe River Catchment which is a sub-catchment of the Zambezi Basin drew the attention of researchers and policymakers when the Chongwe River started drying up in the dry seasons causing a water crisis particularly in the downstream regions of the middle catchment. Therefore, it is important from the water resources management perspective, to assess the contribution of tributaries into the flows of the Chongwe River. Ngwerere and Kanakatampa streams are socially, economically, and environmentally important streams for the city of Lusaka and surrounding area. This study, therefore, concentrated on evaluating the flow contribution of the two streams to the Chongwe River using the Water Evaluation And Planning (WEAP) tool. The streamflow data (1970-2010) recorded at the Chongwe Great East Road Bridge gauging station were used in the WEAP embedded Parameter ESTimation (PEST) auto-calibration tool to calibrate (1970-1999) and validate (2000-2010) the model. The monthly streamflow model calibration and validation results were assessed using the correlation coefficient (CC), Coefficient of determination (R2), Nash-Sutcliffe Coefficient of Efficiency (NSE), and Percent bias (PBIAS). The model performance results achieved were PBIAS of 1.24%, CC = 0.81, R2 = 0.66 and NSE = 0.62 during the calibration period and a positive PBIAS of 2.94%, CC = 0.81, R2 = 0.67 and NSE = 0.62 during the validation period. The median of the flows (Q50) was obtained from the historical flow duration curves (FDCs) generated in averaged intervals of 10-year from 1970 to 2019. The results showed that on average, the Ngwerere and Kanakatampa Streams contribute 52.8% and 29.6% respectively, to the flow of the Chongwe River in the upper and middle Catchment. The results also showed that the contribution of the Ngwerere and Kanakatampa Streams to the Chongwe River discharge has been reducing historically at a rate of 0.65% per decade and 1.35% per decade respectively over a period of 50 years (1970-2019). Suggestions for sustainable management of the tributaries such as the Ngwerere and Kanakatampa Streams were provided in this study.

An Investigation of Waste Management Practices in the Zambian Construction Industry

This study investigated the practice and perceptions on waste management and the feasibility of establishing a site waste management plan in the Zambian Construction Industry (ZCI). In this research, Lusaka and the Copperbelt provinces were selected as study areas to represent the construction industry in Zambia. This was because the largest volume of construction work in the country is mainly concentrated in these two provinces. The research targeted contractors from Grades 1 to 3 as categorised and registered by the Zambian National Council for Construction (NCC). Consultancy firms and government institutions were also included in the target population as regulators. Data for this study were obtained through questionnaires, interviews and site surveys. The results from this research indicated that disposal was the most common method of waste management in the Zambian Construction industry as indicated by the highest ranking score with a mean index of 0.923. The research concluded that the construction industry in Zambia has poor practice of waste management through waste disposal which is not environmentally friendly. The results further indicated that it is feasible to adopt a Site Waste Management Plan in the Zambian Construction industry based on the respondents’ willingness mean score of 0.94 from all the categories. Finally, the research confirmed that a Site Waste Management Plan can be an effective tool to address waste management challenges in the Zambian Construction Industry based on the literature review and willingness measured from research respondents.

Assessing the Potential Presence and Impact of Nile tilapia, Oreochromis niloticus (Pisces: Cichlidae;Linnaeus 1758) in Mutukutuku Reservoir in Solwezi, Zambia

Invasive alien species are one of the greatest threats to biodiversity and ecosystem globally,affecting delivery of ecosystem goods and services,and consequently human well-being.Oreochromis niloticus is one of the most highly successful invaders of aquatic ecosystems with competitive characteristic advantages over indigenous species.The aim of this study was to investigate the potential presence and impact of O.niloticus on Mitukutuku fishery.The study was undertaken using fisheries independent surveys for the period of 2 months.Fish identification key and gel electrophoresis identification methods were also used to confirm presence of O.niloticus and also possible hybridization with indigenous congeneric species.Fisheries dependent survey was conducted with fishers and traders to further assess presence of the invasive species and its impacts on their catches and socio-economic well-being.A total of 32 Oreochromis hybrids species and 19 of O.niloticus were found in the reservoir.This confirmed a higher proportion of O.niloticus in the reservoir.Results from interviews of fishers and traders revealed catch per unit effort of O.hybrids and O.niloticus to be higher compared to that of indigenous congeneric species.Similarly,fish traders confirmed that income for the fish sales increased from 5%in March to 7%in August.Overall,these results suggested that O.niloticus does not only exist in Mitukutuku reservoir,but also hybridizes with native species and dominates the entire stretch of the reservoir threatening loss of biodiversity and aquaculture breeding programme.There is need for restricting culture of O.niloticus in Zambia.

Solving Different Types of Differential Equations Using Modified and New Modified Adomian Decomposition Methods

The Modified Adomian Decomposition Method (MADM) is presented. A number of problems are solved to show the efficiency of the method. Further, a new solution scheme for solving boundary value problems with Neumann conditions is proposed. The scheme is based on the modified Adomian decomposition method and the inverse linear operator theorem. Several differential equations with Neumann boundary conditions are solved to demonstrate the high accuracy and efficiency of the proposed scheme.

Correlation in Gamma Ray Burst Time Delays between Pairs of Radio Photons

We present a pilot study of time delays Δt in four GRB Radio Afterglow emissions, i.e., delays in the arrival times of radio waves of different frequencies emanating from eight GRB Radio Afterglows. Unlike in most studies on this phenomenon, we do not assume that this time delay is due to the Photon being endowed with a non-zero mass, but that this may very well be due to the interstellar space being a cold rarefied cosmic plasma, which medium’s Electrons interact with the electric component of the Photon, thus generating tiny currents that lead to dispersion, hence, a frequency (v) dependent speed of Light where this speed scales off as v-1. The said interaction is such that, lower frequency Photons will propagate at lower speeds than higher frequency Photons thus leading to the observed time delays in the arrivals times of Photons of different frequencies. In reasonable accord with the proposed model, we find that for four of these GRB afterglows, there is a strong unsolicited correlation between the observed time delays and the frequency. If this model can be corroborated by a large enough data set, there is hope that this same model might lead to a better understanding of the observed time delays in GRBs.

Prevalence and predictors of smoking in a mining town in Kitwe, Zambia: A 2011 population-based survey

Smoking is one of the major preventable causes of death and non-communicable diseases which include hypertension, cardiovascular diseases and cancers. The aim of the study is to establish prevalence and predictors of smoking so that interventions specific to these communities can be executed to prevent smoking. A cross sectional study was conducted using a modified World Health Organizations Global Non Communicable Diseases (NCD) Surveillance Initiative NCD-STEPs 1 and 2. Multivariate logistic regression was used to examine the determinants of tobacco smoking. A total of 1627 individuals participated in the survey, of which 42.3% were males. About half of the participants were of age 25-34 years (56.0%), and 41.7% had attained secondary level of education. Overall, 8.7% of the participants (18.1% among males and 1.8% among females) currently smoked any tobacco product. Female respondents were 71% (AOR = 0.29, 95%CI [0.21, 0.39]) less likely to smoke cigarettes compared to male respondents. Compared to respondents who had no formal education, respondents who had attained primary level of education were 45% (AOR = 1.45, 95%CI [1.02, 2.08]) more likely to smoke, and those who attained college or university level of education were 57% (AOR = 0.43, 95%CI [0.28, 0.65]) less likely to smoke. Respondents who did not consume alcohol were 50% (AOR = 0.50, 95%CI [0.41, 0.61]) less likely to smoke compared to those who consumed alcohol. The study showed that sex, education, and alcohol consumption were independently associated with Smoking. These are the key determinants which should be considered when designing a health education and awareness campaign to the residents.

Correlation of Performance, Exhaust Gas Temperature and Speed of a Spark Ignition Engine Using Kiva4

The objective of this study was to investigate performance characteristics of a spark ignition engine, particularly, the correlation between performance, exhaust gas temperature and speed, using Kiva4. Test data to validate kiva4 simulation results were conducted on a 3-cylinder, four-stroke Volkswagen (VW) Polo 6 TSI 1.2 gasoline engine. Three different tests were, therefore, carried out. In one set, variations in exhaust gas temperature were studied by varying the engine load, while keeping the engine speed constant. In another test, exhaust gas temperature variations were studied by keeping the engine at idling whilst varying the speeds. A third test involved studying variations in exhaust gas temperature under a constant load with variable engine speeds. To study variations in exhaust gas temperatures under test conditions, a basic grid/mesh generator, K3PREP, was employed to write an itape17 file comprising of a 45° asymmetrical mesh. This was based on the symmetry of the combustion chamber of the engine used in carrying out experimental tests. Simulations were therefore performed based on the input parameters established in the conducted tests. Simulations with the kiva4 code showed a significant predictability of the performance characteristics of the engine. This was evident in the appreciable agreement obtained in the simulation results when compared with the test data, under the considered test conditions. A percentage error, between experimental results and results from simulations with the kiva4 code of only between 2% to 3% was observed.

《中非关系史上的丰碑:援建坦赞铁路亲历者的讲述》书评

坦赞铁路东起坦桑尼亚的达累斯萨拉姆,西抵赞比亚中部的新卡皮里姆波希,全长1860.5公里。这是连接东部非洲与中部和南部非洲的铁路干线,非洲人普遍誉为自由之路和友谊之路。具有讽刺意味的是,坦赞铁路的修建实现了殖民者塞西尔·罗兹修建从开普敦到开罗的铁路之梦。此书分为三部分,再细分为若干章。第一部分是中华人民共和国参与建设坦赞铁路的亲历者回忆叙述。