Articles

Risk Assessment of Toxicologically Relevant Metals (TRMs) in Urban Surface Soils and Columba livia Feathers

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Metals of toxicological interest (MTI: cadmium [Cd], chromium [Cr], mercury [Hg], and lead [Pb]) are priority contaminants in urban environments due to their persistence, bioavailability, and potential toxicity to ecosystems and human health. In this study, their presence in urban surface soils was determined using quantitative analytical chemistry techniques, and ecological risk (Er), non-carcinogenic risk (HQ), and carcinogenic risk (CRi) were assessed. Additionally, ecotoxicological risk (RQ) was estimated using Columba livia feathers as a biomonitor.

The results confirmed the presence of all four MTI in the analyzed soils, with low ecological and non-carcinogenic risk values. However, a relevant individual carcinogenic risk associated with Cd was identified, particularly in the child population. In Columba livia feathers, Cd and Hg showed high bioaccumulation, with very high RQ values (>400), indicating cumulative exposure in urban biota.

Overall, these findings suggest that, although soil concentrations do not exceed regulatory thresholds, bioaccumulation processes may increase the risk in living organisms, highlighting the importance of incorporating biomonitors into environmental assessments of urban systems.

Water Quality Assessment of Lower Usuma Dam Water from Treatment plant to points of Consumption in Federal Capital Territory, Nigeria

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This study investigated and compared the bacteriological, physicochemical and heavy metals concentrations of drinking water quality of Lower Usuma Dam from treatment plant to the points of consumption in three Area Councils (Bwari, Abuja Municipal and Gwagwalada) of the Federal Capital Territory, Abuja, Nigeria.  Most probable number technique was employed for coliform detection. Molecular characterization of isolated bacteria was carried out. Seven out of the 26 water samples analyzed in this study were contaminated in the range of 7 MPN/100ml to >23 MPN/100ml. Physicochemical parameters such as colour, pH, temperature, turbidity, total dissolved solids (TDS), total hardness, electrical conductivity, total alkalinity and seven heavy metals were also determined using Atomic absorption spectrophotometry. Results showed that Bwari had the highest value for colour, 16.67 Pt.Co while AMAC had the least with 1.00 Pt. Co, Gwagwalada had the highest pH value (7.33±0.12) and Bwari the lowest pH of 6.77±0.06. Bwari also had highest temperature of 30.23±2.80oC while AMAC recorded the least (27.29±0.26oC). Turbidity ranged from 1.86 to 2.83 NTU. The highest level of the other parameters [(TDS 54.27 mg/L, conductivity 90.10 µs/cm, total hardness 34.00 mg/L, total alkalinity 28.00 mg/L, Cl– 20.82 mg/L)] was observed in water samples from Gwagwalada Area Council. Gwagwalada recorded the highest values for iron and zinc at 0.09mg/l and 0.003mg/l respectively. Copper concentration was highest in AMAC (0.043mg/l) and lowest in Bwari area council (0.007mg/l). There was no significant difference (p>0.05) in the concentration of Cr detected in all the water samples. There is need for provision of adequate sanitation facilities and improvement on monitoring of distribution system in order to maintain drinking water quality and prevent water borne disease outbreaks.

Spectrophotometric Determination of Cd (II) Heavy Metal by Using Stone Apple Shell as a Low Cost Adsorbent

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The toxic element Cadmium (II) was determined by using the widely and easily available shells of fruits of stone apple with a good result. The cadmium is a highly toxic element in a trace amount also, therefore its detection is most important. In the present work the effective and powerful adsorbent properties of shells of waste fruits of stone apple (Aegle marmelos) were thoroughly studied. In this work the determination of Cadmium (II) heavy metals from the solutions of its salt were efficiently carried out. The efficiency of removal of Cd (II) was found to be 85 % at the optimum pH 6.7 and the contact time was 118 min for the toxic metal Cadmium (II). The adsorbent used in the present work was ecofriendly cost effective and easily available and will become the better substitute adsorbent for the removal of heavy metal Cd (II). The different parameters such as contact time, effect of pH, initial concentration of metal ions and amount of adsorbent on the adsorption capacity were studied by using the double beam UV-Visible Spectrophotometer.

Application of Activated Afzelia Africana and Acacia Albida Carbon for Removal of Pollutants in Textile Wastewater

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Adsorption of contaminants in textile wastewater onto activated carbon derived from two wood species has been studied using batch-adsorption techniques. This study was carried out to examine the removal efficiency of the low-cost adsorbent (Afzelia africana) AFA and (Acacia albida) ACA for the removal of heavy metals and other organic contaminants from textile effluents. The influence of contact time and adsorbent dose kept constant on the adsorption process was also studied. Removal efficiency increased with increase in contact time. The two adsorbents had an average removal efficiency of 60% at 90mins contact time for Zn. The ACA had higher removal efficiency for chromium at all contact times than AFA except at 120mins contact time where there existed a slight difference in the removal efficiency between the two adsorbents. Removal efficiency of iron was high between 58.18- 70.52% and 72.75-75.86% for AFA and ACA carbon respectively. This showed that iron had high affinity to the adsorbents surface. It was observed that AFA exhibited highest removal efficiency for nitrate at all contact times as compared to ACA. Results indicated that the freely abundant, locally available, low-cost adsorbent derived from the two wood species could be treated as being economically viable for the removal of contaminants from textile effluents.