{"title":"Co-occurrence of cadmium and ciprofloxacin in environmental media decreases ciprofloxacin degradation by biogenic manganese oxides","authors":"Jingjing Qiu, Zuxin Xu, Bin Dong, Mei Wang","doi":"10.1016/j.envpol.2024.125488","DOIUrl":null,"url":null,"abstract":"The coexistence of antibiotics with heavy metals is detrimental to humans and the environment. In urban water environments, Cadmium (Cd) and ciprofloxacin (CIP) frequently co-occur. Biogenic manganese oxides (BMOs) are a promising environmental bioremediation material due to their remarkable adsorption and oxidation properties. However, BMOs’ removal mechanism in an environment where Cd and CIP co-occur is not yet unknown. We identified a manganese (Mn)-oxidising bacterium, <em>Bacillus</em> sp. XM02, with a strong ability for Mn (II) oxidation (85.23%) and BMOs production, and investigated its competitive removal mechanism in an environment with Cd and CIP co-occurrence. The BMOs exhibited a glorious CIP degradation ability and led to a marked decrease in the toxicity of CIP following oxidative degradation in <em>Escherichia coli</em> experiments. In contrast, in the co-existence of Cd and CIP, Cd hindered CIP removal by BMOs, but CIP did not affect Cd removal. Kinetic experiments combined with XPS characterisation revealed that the <em>k</em> value of Cd (297.39 h<sup>-1</sup>) was much higher than that of CIP (5.53 h<sup>-1</sup>), demonstrating that Cd was immediately adsorbed onto the surface of BMOs through a Cd-O bond. The surface potentials of BMOs carrying Cd alone and both Cd and CIP on the surface were similar, revealing that the electronegativity of Cd-carrying BMOs was greatly weakened (from -34.8 mV to -21 mV/-23 mV), which further reduced the BMOs’ electrostatic interaction with CIP. Moreover, the concentration of dissolved Mn (III) in the co-existence group was lower than that in the CIP alone, indicating that the presence of Cd reduced the transformation of Mn (IV) to Mn (III) by BMOs. Consequently, Cd attenuated the effect of active Mn (IV) sites of BMOs on CIP’s piperazine ring oxidative degradation. These results offer a theoretical direction for the use of BMOs to reduce the risk posed by antibiotics and heavy metals pollution in co-occurrence environments.","PeriodicalId":311,"journal":{"name":"Environmental Pollution","volume":"8 1","pages":""},"PeriodicalIF":7.6000,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Environmental Pollution","FirstCategoryId":"93","ListUrlMain":"https://doi.org/10.1016/j.envpol.2024.125488","RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
The coexistence of antibiotics with heavy metals is detrimental to humans and the environment. In urban water environments, Cadmium (Cd) and ciprofloxacin (CIP) frequently co-occur. Biogenic manganese oxides (BMOs) are a promising environmental bioremediation material due to their remarkable adsorption and oxidation properties. However, BMOs’ removal mechanism in an environment where Cd and CIP co-occur is not yet unknown. We identified a manganese (Mn)-oxidising bacterium, Bacillus sp. XM02, with a strong ability for Mn (II) oxidation (85.23%) and BMOs production, and investigated its competitive removal mechanism in an environment with Cd and CIP co-occurrence. The BMOs exhibited a glorious CIP degradation ability and led to a marked decrease in the toxicity of CIP following oxidative degradation in Escherichia coli experiments. In contrast, in the co-existence of Cd and CIP, Cd hindered CIP removal by BMOs, but CIP did not affect Cd removal. Kinetic experiments combined with XPS characterisation revealed that the k value of Cd (297.39 h-1) was much higher than that of CIP (5.53 h-1), demonstrating that Cd was immediately adsorbed onto the surface of BMOs through a Cd-O bond. The surface potentials of BMOs carrying Cd alone and both Cd and CIP on the surface were similar, revealing that the electronegativity of Cd-carrying BMOs was greatly weakened (from -34.8 mV to -21 mV/-23 mV), which further reduced the BMOs’ electrostatic interaction with CIP. Moreover, the concentration of dissolved Mn (III) in the co-existence group was lower than that in the CIP alone, indicating that the presence of Cd reduced the transformation of Mn (IV) to Mn (III) by BMOs. Consequently, Cd attenuated the effect of active Mn (IV) sites of BMOs on CIP’s piperazine ring oxidative degradation. These results offer a theoretical direction for the use of BMOs to reduce the risk posed by antibiotics and heavy metals pollution in co-occurrence environments.
期刊介绍:
Environmental Pollution is an international peer-reviewed journal that publishes high-quality research papers and review articles covering all aspects of environmental pollution and its impacts on ecosystems and human health.
Subject areas include, but are not limited to:
• Sources and occurrences of pollutants that are clearly defined and measured in environmental compartments, food and food-related items, and human bodies;
• Interlinks between contaminant exposure and biological, ecological, and human health effects, including those of climate change;
• Contaminants of emerging concerns (including but not limited to antibiotic resistant microorganisms or genes, microplastics/nanoplastics, electronic wastes, light, and noise) and/or their biological, ecological, or human health effects;
• Laboratory and field studies on the remediation/mitigation of environmental pollution via new techniques and with clear links to biological, ecological, or human health effects;
• Modeling of pollution processes, patterns, or trends that is of clear environmental and/or human health interest;
• New techniques that measure and examine environmental occurrences, transport, behavior, and effects of pollutants within the environment or the laboratory, provided that they can be clearly used to address problems within regional or global environmental compartments.