The uptake and impact of CdS and ZnO NPs in/on maize roots and shoots was investigated and compared with their soluble bulk materials (ZnClz and CdClz). The plants were grown in Eutric Cambisol soil for 21 days. The soil was treated with seven concentrations (0.1-1.25 mg kg-I) for each metal. The Tolerance Index (T!), the Agronomical Efficiency (AE), the Bio-Concentration Ratio (BCR), the Relative Increase Percentage (RI), uptake and uptake %. were calculated for maize roots and shoots. The concentration of metals in maize roots and shoots following treatments of soil with either NPs or bulk materials increased relative to control samples. In addition, the concentration of all metals was higher in maize roots than in shoots across all metals concentrations studied. The uptake of Cd and Zn by maize roots and shoots grown in soils treated with bulk compounds was higher than for those grown in equivalent treated soil with NPs. The majority of NPs and their bulk materials had no significant negative effects on maize growth parameters. However, CdS NPs, CdClz and ZnO NPs had negative effects on the length of maize roots and shoots at the highest metal soil ratio (1.0 and 1.25 mg kg-I). The calculated maize growth parameters (TI, AE, BCR, RI, uptake and uptake %) were varied in maize roots and shoots depending on the plant part, growth period and metal treatments. The toxic effects of CdS NPs (0-100 mg L-1) and ZnO NPs (0-1000 mg L-1) on the germination and the development of maize root were studied for 8 days. The results indicated that the concentration of Zn in maize seeds and roots was higher than Cd for equivalent initial NPs concentrations. Most of the NP concentrations studied had a negative effect on the length and dry weight of maize roots. Germination of maize seed was reduced by the ZnO NPS (68.6%) more than that of CdS (58.1 %). The uptake of CdS, ZnO, and CuO NPs was also investigated for maize plants grown in Eutric Cambisol soil and hydroponic culture over 21 days. High NPs concentrations were used across both growth mediums (0.01-1.0 g kg-1 /g L-1). The TI, AE, BCR, RI, uptake and uptake % were also calculated for maize roots and shoots. The concentration of all NPs showed a similar trend of accumulation behaviour in maize roots and shoots to those found in low concentrations of NPs « 1.25 mg kg-1). The concentration of all metals in maize roots and shoots grown in nutrient solution containing NPs was higher than those grown in the NP treated soil. In addition, the impact of all NPs indicate that CuO and CdS NPs has negative effect on the length of maize roots and shoots at the highest concentrations in both cultures. Moreover, the dry weight of maize shoots was decreased by CdS NPs at the highest concentration in hydroponic culture. The calculated maize growth parameters were also varied in maize roots and shoots depending on the plant part, growth period and metal concentrations. The adsorption kinetics and desorption % of CdS, ZnO, and CuO NPs was studied on the surface of four soils using the batch method. Adsorption isotherms were evaluated by Freundlich and Langmuir model. The results of study suggest that the adsorption of all NPs increased as a function of increasing NPs concentrations until the adsorption equilibrium was reached across all soils. The relative mean adsorption of NPs in four soils was found to follow the following order: Cu > Cd >' Zn. Results also indicated that the highest adsorption of NP on soils was as follows: Libyan sandy soil> Eutric Cambisol soil > Sandy soil > Haplic podzol soil. The adsorption results for all NPs were best modelled using Freundlich equation across all soils. The kinetic behaviour of all studied NPs toward four soils showed the pseudo-second order rather than pseudo-first order kinetics. The mean desorption % of NPs in four soils was found to follow the following order: Zn > Cd > Cu. The effect of CdS, CuO, and ZnO NPs on the rate of nitrogen mineralization was investigated in Eutric Cambisol, Haplic podzol, and Sandy soil over 28 days, three concentrations of each metal NP were used (0.01-l.0 g kg-1). The influence of all test NPs on soils respiration rate was also examined for 48 hours using the same NPs concentrations above. The results of nitrogen mineralization revealed that, the concentration of nitrate (N03-) accumulated readily in three soils; however, the concentrations of ammonium (NH/), dissolved organic nitrogen (DON) and free amino acids had low levels of accumulation across all of test soil and NP types. The comparison results of NPs impact indicated that the large majority of NPs failed to reveal any significant effect upon nitrogen mineralization under any of the NP concentrations save that for amino acid concentrations. Results of soil respiration revealed that no negative significant impacts for all NPs on soil respiration across all NPs and soil types.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:664486 |
| Date | January 2014 |
| Creators | Abdalgader, Naser |
| Contributors | Laws, Jason ; Mulhearn, Chris |
| Publisher | Bangor University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.jmu.ac.uk:8881/R/?func=dbin-jump-full&object_id=158084 |
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