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Showing 3 results for Humic Acid
Effect of HumicAcid on Sorption and Desorption of Zinc
M. Piri, E. Sepehr,
Volume 19, Issue 72 (8-2015)
Abstract
Humic substances are the most important organic fractions in soils and have affinity towards trace metals. In order to evaluate the effect of humic acid on zinc (Zn) sorption and desorption by soil,‌ a batch experiment was conducted with two soil samples which were different in clay and calcium carbonate contents. Three levels of humic acid (0,‌ 200, 500 mg/L) and various Zn concentrations (0 to 450 mg/‌L) were applied at constant ionic strength (0.05 M NaCl). Adsorption data were fitted to Langmuir, Freundlich and Temkin equations. Freundlich equation fitted relatively better (R2= 0.86-0.98). Results showed that the application ofhumic acid increased both ‌sorption and desorption of Zn in the two sample soils. Increasing of humic acid concentration increased maximum adsorption of Langmuir (qmax) up to 8-21% and Freundlich sorption capacity (Kf) up to 73-95%.‌ All sorption parameters including‌ Langmuir binding energy (KL), Freundlich intensity factor (n) and coefficients of Temkin equation (A, KT) were increased by adding humic acid, so that the above mentioned sorption parameters of S1 (with low clay and calcium carbonate) were lower than those of S2 (with high clay and calcium carbonate). Application ‌of humic acid (500 mg/L) increased desorption of Zn (DTPA-Zn) ‌from 511 to 711 mg/kg for S1 and 499 to 609 for S2‌.
Effects of Phosphorous Fertilizers and Arbuscular Mycorrhiza Fungi Symbiosis with Sunflower on Pb Availability in a Contaminated Soil
M. Amouzegar, A. Abbaspour, Sh. Shahsavani, H. R. Asghari , M. Parsaeiyan,
Volume 19, Issue 74 (1-2016)
Abstract

Soil contamination by Pb leads to a reduction in the quality and quantity of crop yield, because it is highly toxic in soluble ionic forms. The availability of this element for plant roots can reduce by the formation of compounds with low solubility and their sedimentation by phosphorous amendments.. Root symbiosis with mycorrhizal fungi can also increase plant resistance against heavy metals. This study was carried out as a factorial experiment in a randomized complete block design asa greenhouse experiment on sunflower plant at Shahrood University. Treatments included mycorrhizal fungi with two levels of inoculation, (with and without inoculation), organic and inorganic phosphorous fertilizers such as humic acid, diammonium phosphate, bone meal and bone meal+humic acid. The results showed that inoculation with mycorrhizal fungi resulted in a significant increase (P&ge0.05) in percentage of mycorrhizal colonization and an increase in soil EC,shootdry weight and phosphous uptake by the plant. Phosphorus fertilizers significantly increased the available phosphorus in soil, dry weight and uptake of phosphorus by the shoots. The interaction effects of mycorrhiza and phosphorus fertilizers on soil exchange able Pbwere significant. The application of diammonium phosphate and mycorrhiza had the greatest impacton the reduction of Pb (by 25.48percent) in the soil exchange. Mycorrhizal plants had a lower rate of lead concentrations in shoots, which was equal to 78/14%, and also the application of phosphorus fertilizers significantly reduced Pb in plant shoots.


The Effect of Humic Acid on the Phytoremediation Efficiency of Pb in the Contaminated Soils by Wormwood Plant (Artemicia absantium)
M. H. Rasouli-Sadaghiani, H. Karimi, S. Ashrafi Saeidlou, H. Khodaverdiloo,
Volume 22, Issue 4 (3-2019)
Abstract
Because of the undesirable effects of lead on soil properties and human health, evaluation of its remediation methods seems to be essential. In order to evaluate the effect of humic acid (HA) on the  decontamination of lead (Pb) spiked-soils in the presence of wormwood plant (Artemicia absantium), an experiment was carried out in a completely randomized  block design with three replications. Experiment factors including different concentrations of Pb (Pb(NO3)2 in the  solid form) (0, 250, 500 and 1000 mg kg-1) and levels of HA (0, 100 and 200 mg kg-1) were considered. At the end of the growing period of plants, some soil and plant properties were measured. According to the results, BR, MBC, root and shoot dry weights, RWC and Fe and Zn concentrations in the shoot were decreased by increasing the soil Pb concentration. So, the mean values of BR and MBC in Pb1000 treatment was 60 and 51.1 percent lower than those of Pb0, respectively. Pb accumulation in the root and shoot was enhanced as a result of the increase in the soil Pb concentration. The maximum Pb concentration of shoot (37.10 mg kg-1) and root (38.1 mg kg-1) was seen in the Pb1000 treatment. Also, the results suggested that humic acid had a positive effect on the shoot of Fe, Zn and Pb concentrations. So, the concentration of these elements in HA200 treatment showed an increase 1.25, 1.64 and 1.66 times more than that of HA0, respectively. Leaf proline amount was increased significantly by elevating the soil Pb concentration; however, application of 200 mg kg-1 humic acid decreased leaf proline by 54.5 percent, as compared to the control (HA0). Therefore, humic acid effect on increasing the plant Pb uptake, improving soil biological properties, and increasing availability and dissolution of Pb showed its ability in promoting the phytoremediation efficiency. According to the obtained results of this study, woodwarm plant (Artemicia absantium) is a non-accumulator that could not be used for phytoremediation purposes.

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