Dataset Information

Adsorption of phenylurea herbicides by tropical soils.

ABSTRACT: The distribution of pesticides in soils with consequences for their mobility, bioavailability and water contamination is mainly ruled by sorption processes. Such processes are seldom investigated in tropical soils. Thus, specific interactions between tropical soils and most pesticides are widely unknown. Furthermore, the question arises whether the same factors govern adsorption in tropical and temperate soils. Thus, the sorption behaviour of five phenylurea herbicides (PUHs) was studied in eighteen differently composed soils originating from southwestern Nigeria. Sorption data were obtained by equilibrating the soil samples with 0.01 M CaCl2 solutions spiked with increasing concentrations of the target PUHs. The equilibrium data fitted well to the Freundlich isotherm equation (R2???0.96), delivering the corresponding parameters (Kf and n). Linear distribution coefficients (Kd) were also calculated. The Pearson correlation was used to identify the specific soil and herbicide properties that have statistically significant correlations with sorption parameters. High correlations were established for various soil properties (pH, cation exchange capacity, organic carbon content, content of amorphous Fe and Mn oxides, clay/silt mass proportions) as well as molecular descriptors (octanol-water partition coefficient (log Kow) and molecular mass (Mw)) of the moderately hydrophobic herbicides. Monuron, chlorotoluron and isoproturon showed higher affinities for soil than previously reported. The gathered knowledge might assist in the assessment and in the precautionary avoidance of potential risks generated by these compounds in tropical soils.

SUBMITTER: Agbaogun BK

PROVIDER: S-EPMC7056688 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Adsorption of phenylurea herbicides by tropical soils.

Agbaogun Babatunde Kazeem BK Fischer Klaus K

Environmental monitoring and assessment 20200304 4

The distribution of pesticides in soils with consequences for their mobility, bioavailability and water contamination is mainly ruled by sorption processes. Such processes are seldom investigated in tropical soils. Thus, specific interactions between tropical soils and most pesticides are widely unknown. Furthermore, the question arises whether the same factors govern adsorption in tropical and temperate soils. Thus, the sorption behaviour of five phenylurea herbicides (PUHs) was studied in eigh ...[more]

PMID: 32133572

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Project description:The synergistic relationships between plants and their rhizospheric microbes can be used to develop a combinational bioremediation method, overcoming the constraints of individual phytoremediation or a bioaugmentation method. Here, we provide a combinational transgenic plant-microbe remediation system for a more efficient removal of phenylurea herbicides (PHs) from contaminated sites. The transgenic Arabidopsis thaliana plant synthesizing the bacterial N-demethylase PdmAB in the chloroplast was developed. The constructed transgenic Arabidopsis plant exhibited significant tolerance to isoproturon (IPU), a typical PH, and it took up the IPU through the roots and transported it to leaves, where the majority of the IPU was demethylated to 3-(4-isopropylphenyl)-1-methylurea (MDIPU). The produced intermediate was released outside the roots and further metabolized by the combinationally inoculated MDIPU-mineralizing bacterium Sphingobium sp. strain 1017-1 in the rhizosphere, resulting in an enhanced and complete removal of IPU from soil. Mutual benefits were built for both the transgenic Arabidopsis plant and strain 1017-1. The transgenic Arabidopsis plant offered strain 1017-1 a suitable accommodation, and in return, strain 1017-1 protected the plant from the phytotoxicity of MDIPU. The biomass of the transgenic Arabidopsis plant and the residence of the inoculated degrading microbes in the combinational treatment increased significantly compared to those in their respective individual transgenic plant treatment or bioaugmentation treatment. The influence of the structure of bacterial community by combinational treatment was between that of the two individual treatments. Overall, the combination of two approaches, phytoremediation by transgenic plants and bioaugmentation with intermediate-mineralizing microbes in the rhizosphere, represents an innovative strategy for the enhanced and complete remediation of pollutant-contaminated sites.IMPORTANCE Phytoremediation of organic pollutant-contaminated sites using transgenic plants expressing bacterial enzyme has been well described. The major constraint of transgenic plants transferred with a single catabolic gene is that they can also accumulate/release intermediates, still causing phytotoxicity or additional environmental problems. On the other hand, bioaugmentation with degrading strains also has its drawbacks, including the instability of the inoculated strains and low bioavailability of pollutants. In this study, the synergistic relationship between a transgenic Arabidopsis plant expressing the bacterial N-demethylase PdmAB in the chloroplast and the inoculated intermediate-mineralizing bacterium Sphingobium sp. strain 1017-1 in the rhizosphere is used to develop an intriguing bioremediation method. The combinational transgenic plant-microbe remediation system shows a more efficient and complete removal of phenylurea herbicides from contaminated sites and can overcome the constraints of individual phytoremediation or bioaugmentation methods.

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Dataset Information

Adsorption of phenylurea herbicides by tropical soils.

Publications

Adsorption of phenylurea herbicides by tropical soils.

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