Effect of low-molecular-weight organic acids on phosphorus soil activation: A laboratory study of the soils from Wangbeng section of the Huaihe River Basin, China

Farmland soil samples from the northern and southern banks of the Wangbeng section of the Huaihe River Basin, China, were collected and treated with three different low-molecular-weight organic acids (LMWOAs) (malic acid, citric acid, oxalic acid). This study aimed to determine how these acids affect soil phosphorus activation. The results showed that the average activation rate of total phosphorus, inorganic phosphorus, Fe/Al-P and Ca-P in soil samples from the southern bank treated with malic and citric acid was above 162%, except for organic phosphorus, with the highest at 192.04%. The three organic acids displayed significantly greater phosphorus activation in the northern bank soil samples than those of the southern bank. However, the overall average activation rate in the northern bank soils was lower than that of the southern bank. The four factors of phosphorus species, acid species, acid concentration, and treatment time had significant effects on phosphorus activation in the soils from both banks. This study showed that the three organic acids significantly activated inert phosphorus in the soil. Among them, malic acid and citric acid had a stronger effect on activating soil phosphorus and increased the available soil phosphorus utilisation rate.

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Organic acids effects on desorption of heavy metals from a contaminated soil

Scientia Agricola ◽

10.1590/s0103-90162006000300010 ◽

2006 ◽

Vol 63 (3) ◽

pp. 276-280 ◽

Cited By ~ 36

Author(s):

Clístenes Williams Araújo do Nascimento

Keyword(s):

Heavy Metals ◽

Molecular Weight ◽

Citric Acid ◽

Organic Acids ◽

Low Molecular Weight ◽

High Biomass ◽

High Concentration ◽

Accumulation Of Metals ◽

Pb Concentration ◽

Oxalic Acids

Phytoremediation of heavy metals is a biotechnology that extracts metals from soils and transfer them to plant. As hyperaccumulator species have demonstrated low potential for commercial phytoextraction, synthetic chelates have been successfully used to induce accumulation of metals by high-biomass plants. However, they pose serious environmental drawbacks regarding excessive amount of metals solubilized. In search for synthetic chelate-alternatives, this paper evaluate the performance of DTPA, EDTA, citric acid, oxalic acid, vanillic acid, and gallic acid in desorbing Cd, Pb, Zn, Cu, and Ni from soil. DTPA and EDTA were highly effective in desorbing Cd, Pb, Zn, Cu, and Ni from soil. However, the excessively high concentration of metals brought in solution by such chelates limits their application in the field. Citric and oxalic acids desorbed substantial quantities of Zn, Cu, and Ni if applied at 10 or 20 mmol kg-1. At the 20 mmol kg-1 dose, vanillic and gallic acids solubilized significant amounts of Zn, Ni, and Cd from soil. None of the tested low molecular weight organic acids substantially increased the Pb concentration in soil solution.

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