Dissolution of copper oxide nanoparticles is controlled by soil solution pH, dissolved organic matter, and particle specific surface area

Meilan Xu; Yansu Wang; Zuting Mu; Shiwei Li; Helian Li

doi:10.1016/j.scitotenv.2021.145477

Dissolution of copper oxide nanoparticles is controlled by soil solution pH, dissolved organic matter, and particle specific surface area

Sci Total Environ. 2021 Jun 10:772:145477. doi: 10.1016/j.scitotenv.2021.145477. Epub 2021 Jan 30.

Authors

Meilan Xu¹, Yansu Wang¹, Zuting Mu¹, Shiwei Li¹, Helian Li²

Affiliations

¹ School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China.
² School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China. Electronic address: chm_lihl@ujn.edu.cn.

PMID: 33578145
DOI: 10.1016/j.scitotenv.2021.145477

Abstract

Dissolution is the primary process affecting the bioavailability and toxicity of nanoscale copper oxide (nano-CuO) to plants and soil organisms. In this study, particle morphology, organic acid, and soil properties were considered to understand the dissolution characteristics of nano-CuO in soil solutions. The results showed that the copper ions (Cu²⁺) released from spherical nano-CuO (CuO NPs), tubular nano-CuO (CuO NTs), and spherical microsized CuO (CuO MPs) in the ten soil solutions were 26.6-4194.0 μg/L, 4.90-217.1 μg/L, and 10.8-326.0 μg/L, respectively. The concentration of Cu²⁺ was negatively correlated with the pH of the soil solution and positively correlated with the contents of dissolved organic carbon (DOC), aluminum, and manganese. Multivariate stepwise regression analysis indicated that the dissolution of CuO NPs could be well predicted by pH and DOC contents of the soil solutions. In the GD soil solution (acidic), 4- and 8-fold of the DOC content amendments significantly promoted the dissolution of the three sizes of CuOs, resulting in an increase of Cu²⁺ 4.55-11.3 and 5.67-16.2 times, respectively. In the CQ soil solution (neutral), 8-fold DOC amendments increase the release of Cu²⁺ 2.13-16.6 times. While in the SD soil solution (alkaline), promoting effect on the dissolution was only observed for nano-CuOs, with Cu²⁺ elevated by factors of 1.56-4.64 and 1.38-4.48. The amendments of Al³⁺ and Mn²⁺ in soil solution increased the amounts of Cu²⁺ 1.13-4.80 and 1.02-1.46 times in the GD soil solution. In comparison, no significant promoting effects were observed in CQ and SD soil solutions due to their stronger buffering capacities. These findings offer insight into the dissolution behavior of nano-CuOs in soils and be helpful to evaluate their environmental risks.

Keywords: Aluminum ions; Copper oxide nanoparticles; Dissolution; Dissolved organic matter; Manganous ions; Soil solution.