Assessment of the potential uptake of chromium by selected plant species and its concentration along the Klein Windhoek river from the Ujams Industrial Waste Water Treatment Plant in Windhoek
| dc.contributor.author | Iiputa, Gerhard I | |
| dc.date.accessioned | 2022-04-26T15:22:02Z | |
| dc.date.available | 2022-04-26T15:22:02Z | |
| dc.date.issued | 2021 | |
| dc.description | A thesis submitted in fulfillment of the requirements for the Degree of Master of Science in Biology | en_US |
| dc.description.abstract | The aim of the study is in threefold: (i) to assess the potential uptake of Cr(VI) and its potential toxicological effects on the total Chlorophyll content of Rumex lanceolatus and Cullen obtusifolia, exposed to the treated industrial effluent from UWWTP. (ii) To assess the concentration of Cr(VI) discharged from UWWTP into the KWR, its compliance to NWQSE and its behavior in the KWR in relation to the increased distance from the discharge point. (iii) To assess the performance of the UWWTP and its compliance to the NWQSE with regard to the concentrations of solids, organics and nutrients in the effluent discharged into the KWR. Comparisons of the total chlorophyll content and Cr(VI) concentration in the leaves were made between plants growing in exposed sites and the control sites. The total chlorophyll content in the plant leaves was determined using a potable meter SPAD 502Plus in the field, validated against a conventional spectrophotometric method in the laboratory. The Cr(VI) in the leaves was determined by a Direct Spectrophotometric Method, after the leaves were digested with a di-acidic mixture of 4 ml nitric acid (HNO3) and 1 ml hydrochloric acid (HCL) (4:1 v/v). The total chlorophyll content was significantly lower in the plants exposed to Cr(VI) containing effluent than those growing in the control site for both R. lanceolatus (Mann-Whitney U test, U =396, p < 0.001) and C. obtusifolia (t (118) = 4.496, p < 0.001). The results further revealed a significantly higher concentration of Cr(VI) in the plant leaves of R. lanceolatus; from the exposed site; t-test (t(118) = 5.692, p <0.001), but the difference in the Cr(VI) concentration between the two groups was not significant for C. obtusifolia. Simple linear regression analysis revealed a highly significant negative relationship between the Cr(VI) concentration and the total chlorophyll concentration in the leaves of R. lanceolatus exposed to the effluent from UWWTP (r(118) = 0.34, p < 0.001). R. lanceolatus accumulated more Cr(VI) concentration in its leaves and also appeared to be sensitive to high Cr(VI) concentration, as marked by the significant reduction in its chlorophyll content. Interestingly, there was no significant relationship between the Cr(VI) concentration and the total chlorophyll concentration in the leaves of the of C. obtusifolia exposed to the effluent from UWWTP. The study showed that C. obtusifolia use avoidance as a mechanism against Cr(VI) induced stress. Both species need to be investigated further to understand their response to Cr(VI) induced stress at the root level and determine their bio accumulation factors. The UWWTP showed high removal efficiency, and complied with NWQSE general guideline in terms of TSS, COD, TKN and PO4. However, the concentrations of Cr(VI) and TDS discharged from the UWWTP were significantly higher than the allowable concentration limit of 0.05 mg/l Cr(VI) and 500 mg/l TDS as set by the NWQSE (t(59) = 12.475, p < 0.001 and (t(124) = 37.778, p < 0.001 respectively) and could be having negative effects on the environment. It was further shown that the concentration of Cr(VI) in the effluent discharged from UWWTP significantly decreased with the increase in the distance away from the UWWTP discharge point along the KWR (r (5) = 0.88, p = 0.02). This study has demonstrated the need for continually assessing the UWWTP discharged effluent to ensure that the concentrations of Cr(VI) are within the set guidelines as provided by the NWQSE and the WHO. | en_US |
| dc.identifier.uri | http://hdl.handle.net/11070/3147 | |
| dc.language.iso | en | en_US |
| dc.publisher | University of Namibia | en_US |
| dc.subject | Chromium | en_US |
| dc.subject | Plant species | en_US |
| dc.subject | Klein Windhoek river | en_US |
| dc.title | Assessment of the potential uptake of chromium by selected plant species and its concentration along the Klein Windhoek river from the Ujams Industrial Waste Water Treatment Plant in Windhoek | en_US |
| dc.type | Thesis | en_US |