Effect of Exogenous Plant Debris and Microbial Agents on Phytoremediation of Copper-Contaminated Soil in Shanghai

Abstract

Bioaugmentation is an important measure for improving the efficiency of phytoremediation. The objective was to identify the role of exogenous plant debris with different processing and microbial agents for soil characteristics, copper bioavailability and phytoextraction. The experimental design consisted of four blocks, which were divided into 48 plots. Each plot was planted with Fraxinus chinensis and Salix matsudana × alba, which was added to plant composts, woody chips and effective microorganisms (EM) agents, using an orthogonal experimental design. The results showed that the order of bioaugmentation materials on the Cu phytoextraction of two woody species was plant composts > wood chips > EM agents. The best performance of F. chinensis was in the T15 treatment (30% plant composts + 7.5% wood chips + 40 mL·m−2), with phytoextraction of 33.66 mg·m−2, as well as 4.32 mg·m−2 in the T16 treatment (30% plant composts + 15% wood chips) of S. matsudana × alba. Cu was accumulated mainly in the roots of the two woody plants. The phytoextraction of the above-ground parts was promoted by bioaugmentation, due to the improvement in the physical soil characteristics and Cu bioavailability. The phytoextraction performance of F. chinensis was promoted by the improvement in the Cu concentration after treatments, while for S. matsudana × alba, it was the dry biomass. Thus, targeted strengthening measures should be to applied, to improve the efficiency of phytoremediation.

Keywords: copper; organic fertilizers; orthogonal design; phytoextraction; plant composts.

Figure 1

Experimental design of different bioaugmentation measures and planting modes. Note: the circle represents F. chinensis; the triangle represents S. matsudana × alba.

Figure 2

Alpha diversity index statistics of rhizosphere microorganism of F. chinensis in different treatments. (A) Shannon index of OTU level; (B) Chao index of OTU level; (C) Shannoneven index of OTU level. Note: p < 0.05 is marked as asterisk.

Figure 3

Cu concentrations of above-and below-ground parts of two woody species. (A) Cu concentration of F. chinensis; (B) Cu concentration of S. matsudana × alba. Note: Values are mean ± SE. Different letters in a row indicate a significant difference, p < 0.05.

Figure 4

Yields and Cu extraction of above-and below-ground parts of two woody species. (A) Dry biomass of F. chinensis; (B) Dry biomass of S. matsudana × alba; (C) Cu extraction amount of F. chinensis; (D) Cu extraction amount of S. matsudana × alba. Note: Values are mean ± SE. Different letters in a row indicate a significant difference, p < 0.05.