Omoregie, Gloria , Ikhajiagbe, Beckley , Anoliefo, Geoffrey .
Nitrogen uptake and foliar distribution during heavy metal accumulation by young Chromolaena odorata plants.
The present study investigated nitrogen utilization by young plants of Chromolaena odorata during phytoremediation of heavy metal contaminated soil. This study became even more important in the bid to further establish the possible link between nitrogen utilization and the plants phytoremediative capabilities. Equal-sized stem cuttings of Chromolaena odorata (30cm long, 2.5 - 3.0cm) were sown in 5 different metal-contaminated soils of different concentrations based on their ecological screening benchmark values (ESV) (Mn = 50mg/kg, Cd = 4mg/kg, Pb = 50mg/kg, Cu = 100mg/kg and Zn = 50mg/kg). These concentrations were Sub-ESV (control), ESV, 3ESV and 5ESV respectively. After 8 weeks following exposure to test plant to metals, there were significant accumulation of available and non-available forms of the various heavy metals in the leaves. Higher percentage of metals accumulated in the plant tissues were chelated for Cd,Pb and Cu in that order, as compared to others. Foliar stabilization efficiency of Cd, determined as percentage of total accumalated metals that were in the chelated forms, ranged from 32.87 to 38.96% and between 28.89 to35.97% for Pb. Results also showed that nitrogen accumulation significantly (p<0.05) reduced with increased metal concentration in the soil. However, there were no significant changes in ammonia nitrogen in the leaves of the test plant following metal phyto-accumulation (108.54 to 187.34ppm). It was however observed that inspite of the aforementioned changes in nitrogen accumulation associated with metal concentration. Plants accumulates more nitrogen in the metal contaminated soil than in the control soil (>50% accumulation). Comparatively Utilization of nitrate nitrogen was higher than ammonia nitrogen. The relationship between metal and nitrogen accumulation is to the extent that increase metal accumuation enhances nitrogen utilization as deduced from the study.
Keywords: Phytoremediation, nitrogen assimilation, heavy metals, Chromolaena odorata, nitrate, ammonia
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1 - Federal University of Petroleum Resourses, Effurun Warri, Delta State, Environmental Management and Toxicology, Delta State, 320001
2 - University of Benin, Benin City, , Plant Biology and Biotechnology, Benin City, Edo State, 300001
Presentation Type: Oral Paper
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize