Bioavailability and Solubility of Heavy Metals and Trace Elements during Composting of Cow Manure and Tree Litter

Kelvin Reyes Pinto,Víctor Meza-Contreras,Julio César Alegre-Orihuela,Warren Réategui-Romero,Rafael Clemente

doi:10.1155/2020/5680169

Kelvin Reyes Pinto, Víctor Meza-Contreras + Show 3 more

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https://doi.org/10.1155/2020/5680169

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Abstract

Objectives. To characterize the total content of heavy metals (Cd, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) and trace elements (As and Se) of interest, their bioavailability and solubility during the composting of cow manure and tree litter in piles inoculated with beneficial microorganism (IBM), or not inoculated (NBM), on the university campus of the Universidad Nacional Agraria La Molina (UNALM). Methods. The investigation evaluated composting in six piles, three IBM piles and three NBM piles, for 120 days. Every 30 days, a composite sample was taken from each pile. The raw materials used were cattle manure and tree litter. The variables analyzed were the total concentrations (content) of metals and trace elements of interest, extracted with diethylenetriaminepentaacetic acid/pentatetic acid (DTPA) (for the bioavailability study) and extracted with deionized water (for the solubility study). Results. The average values (n = 3) of the total content (mg·kg−1) on day 120 in IBM were in the following order: Zn (404.33) > Cu (86.33) > Pb (71.2) > Cr (34.33) > As (28.0) > Ni (13.83) > Mo (2.86) > Se (1.38) > Cd (1.32) > Hg (0.39) and in NBM: Zn (466.0) > Cu (112.23) > Pb (73.23) > Cr (35.33) > As (29.67) > Ni (14.37) > Mo (3.23) > Se (1.55) > Cd (1.38) > Hg (0.38). The values complied with the Austrian Compost Standard for Landscaping and Land Rehabilitation and the Peruvian Standard for Nonorganic Agriculture. Significant differences were observed in some elements ( p < 0.05) between 0 and 120 days in both types of pile (IBM and NBM). Conclusions. For nonorganic agriculture in Peru, urban compost is recommended, whereby raw organic materials are inoculated with beneficial microorganisms during the composting process to reduce the bioavailability of Cu and Zn, as these elements showed less bioavailability than noninoculated piles. The composting process for both piles (IBM and NBM) reduced the solubility in Cu, Pb, and Zn.

Highlights

To characterize the total content of heavy metals (Cd, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) and trace elements (As and Se) of interest, their bioavailability and solubility during the composting of cow manure and tree litter in piles inoculated with beneficial microorganism (IBM), or not inoculated (NBM), on the university campus of the Universidad Nacional Agraria La Molina (UNALM)
Compared with the Chilean standard [74], we have the pH complying for both types of compost and both classes (A and B); for the electrical conductivity (EC), only tree litter complies for class B compost; total nitrogen (TN) is complied with for both types of compost and for both classes, and the C/N ratio is met in both types of compost and for both classes
It is important to emphasize the value of CE, which can be associated with the type of cattle feed [75]

Summary

Objectives

To characterize the total content of heavy metals (Cd, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) and trace elements (As and Se) of interest, their bioavailability and solubility during the composting of cow manure and tree litter in piles inoculated with beneficial microorganism (IBM), or not inoculated (NBM), on the university campus of the Universidad Nacional Agraria La Molina (UNALM). E objective of this investigation was the characterization of the total content of heavy metals and trace elements of interest, as well as their bioavailability and solubility, during the composting of cow manure and tree litter in piles inoculated, or not inoculated, with beneficial microorganisms on the university campus of the Universidad Nacional Agraria La Molina (UNALM)

Materials

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