Assessing the Impacts of Cu(OH)₂ Nanopesticide and Ionic Copper on the Soil Enzyme Activity and Bacterial Community

Abstract

Nanopesticides are being introduced in agriculture, and the associated environmental risks and benefits must be carefully assessed before their widespread agricultural applications. We investigated the impacts of a commercial Cu­(OH)2 nanopesticide formulation (NPF) at different agricultural application doses (e.g., 0.5, 5, and 50 mg of Cu kg–1) on enzyme activities and bacterial communities of loamy soil (organic matter content of 3.61%) over 21 days. Results were compared to its ionic analogue (i.e., CuSO4) and nano-Cu­(OH)2, including both the commercial unformulated active ingredient of NPF (AI-NPF) and synthesized Cu­(OH)2 nanorods (NR). There were negligible changes in the activity of acid phosphatase, regardless of exposure dose, whereas significant (p < 0.05) variations in activities of invertase, urease, and catalase were observed at a dose of 5 mg kg–1 or higher. Invertase activity decreased with an increasing bioavailable Cu concentration in soil under various treatments. In comparison to CuSO4, both Cu­(OH)2 nanopesticide (i.e., NPF) and nano-Cu­(OH)2 (i.e., AI-NPF and NR) caused a significant (p < 0.05) inhibition of urease activity, wherein a significant (p < 0.05) increase in the activity of catalase was observed, representing serious oxidative stress. Accordingly, NPF, AI-NPF, and NR differently affected soil bacterial abundance, diversity, and community compared to CuSO4, which could have resulted from the changes in the bioavailable Cu concentration as a result of the distinct nature of copper spiked (i.e., nano form versus salt). Moreover, minor differences in the soil enzyme activity and bacterial community were observed between NPF and AI-NPF, reflecting that the impact of the Cu­(OH)2 nanopesticide was primarily attributed to the presence of nano-Cu­(OH)2. In total, the impacts of nano-Cu­(OH)2 on the soil bacterial community and enzyme activity tested in this study differed from CuSO4, shedding light on the environmental risks of the Cu­(OH)2 nanopesticide in the long run.

Interaction between a nano-formulation of atrazine and rhizosphere bacterial communities: atrazine degradation and bacterial community alterations

“…Similar alterations in rhizosphere bacterial communities were also observed in long-term contamination by a metal-based nanopesticide Cu(OH) 2 , 6 and the toxicity of the Cu(OH) 2 nanopesticide was reported to be different from that of the copper compartment. 5 In our results, after long-term exposure, Proteobacteria and Actinobacteria were found to play the most important roles in inducing the differences among rhizosphere bacterial communities in different treatments. Similar positive correlations between the frequencies of Actinobacteria and Proteobacteria and the concentrations of ATZ were also reported in soils containing agrochemicals.…”

“…carbon and phosphorus cycling). 5,6 The potential adverse effects of nano-pesticides on non-target (micro)organisms are however still largely unknown, especially since it has been realized that some nano-pesticides are designed to have enhanced mobility. [7][8][9] As for any newly developed chemical or material, it is critical to understand the possible toxicity of nano-pesticides to non-target (micro)organisms.…”

Fate of copper in soil: effect of agrochemical (nano)formulations and soil properties

“…There is a consensus that the toxicity of Cu (nano or not) in soil is driven by the free Cu 2+ ions available in the soil solution. 20,22,47,55 The slow dissolution of nCuO after application is thus likely to result in a lower short term exposure concentration relative to other forms of Cu, and thus lower toxicity. 23 Further research considering the effect of plants (e.g.…”

Nano-Enable Materials Promoting Sustainability and Resilience in Modern Agriculture

“…In these studies, the impact of a commercial Cu(OH) 2 nanopesticide formulation on bacterial metabolic activity and community structure of loamy soil in comparison with its ionic analog (CuSO 4 ) and nano-Cu(OH) 2 was investigated. As a whole, the impacts of nano-Cu(OH) 2 on soil bacterial community and enzyme activity differed from its ionic analog, showing the environmental risks of nano-Cu(OH) 2 nanopesticides in the long term [ 22 ]. Another informative study provided insights on a commercially available colloid-size Cu(OH) 2 fungicide/bactericide highlighting the influence of elemental composition in addition to physico-chemical properties on the fate, transport, stability, dispersion, and dissolution of the nanoformulations [ 23 ].…”