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Assessing the Impacts of Cu(OH)2 Nanopesticide and Ionic Copper on the Soil Enzyme Activity and Bacterial Community
journal contribution
posted on 2020-03-05, 19:34 authored by Xiaoxia Zhang, Zhenlan Xu, Xiaoting Qian, Daohui Lin, Tao Zeng, Juliane Filser, Lingxiangyu Li, Melanie KahNanopesticides 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.
