Impact of aquatic humic substances on speciation and toxicity of arsenic and cobalt to Ceriodaphnia dubia

Author(s)

Watanabe, Claudia Hitomi ; Gontijo, Erik Sartori Jeunon ; Domingues, Murilo Teles ; Fracacio, Renata ; Rosa, Andre Henrique

• Document type: Journal article
• Source: Environmental Science and Pollution Research; v. N/A, p. 8-pg., 2023-05-30.

Abstract

Humic substances (HS) interact with trace metals such as As and Co, affecting their mobility and availability in aquatic systems. However, their combined effects on toxicity to aquatic organisms are not totally understood. The objective of this study was to evaluate the toxicity of Co(II) and As(III) to the water flea Ceriodaphnia dubia in the presence of HS, considering element speciation. Toxicity assays were performed in the presence and absence of HS at two different concentrations of As(III) (10 and 20 mu g/L) and Co(II) (50 and 100 mu g/L). The free As(III) and Co(II) (< 1 kDa, fraction most potentially bioavailable) in the test solutions were determined via ultrafiltration. While free Co(II) decreased by approximately 80% in the presence of HS, free As(III) decreased just by 1%. Despite the higher percentage of As(III) potentially bioavailable, the presence of HS reduced significantly the toxicity of As at 20 mu g/L (no toxicity was observed at 10 mu g/L). This was attributed to direct effects of HS such as hormesis, hormone-like effects of HS and/or formation of protective coating. These effects also stimulated the reproduction, including in the assays in the absence of As and Co. HS reduced the toxicity of Co(II) at both test concentrations. The results of this investigation support that HS should be considered when safe limits for As and Co are defined. (AU)

• FAPESP's process: 19/06800-5 - Screening of persistent organic pollutants emerging in the waste stream: emphasis on brominated flame retardants (BFRs) and perfluoroalkyl substances (PFASs)
• Grantee: André Henrique Rosa
• Support Opportunities: Scholarships abroad - Research
• FAPESP's process: 13/06000-2 - Phosphates immobilization in polymeric microspheres containing biochar: preparation, characterization and slow release in aqueous systems.
• Grantee: Murilo Teles Domingues
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 12/19580-4 - Ecotoxicological assessment of metals / metalloids and endocrine disruptors in fractions of humic substances of different molecular sizes
• Grantee: Cláudia Hitomi Watanabe
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 12/17727-8 - Distribution, complexation and mobility of arsenic ions in superficial waters in Iron Quadrangle -MG/Brazil: emphasis on interactions with aquatic humic substances
• Grantee: Erik Sartori Jeunon Gontijo
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 14/20979-4 - Transport, availability and ecotoxicology of nanoparticles in the environment: interactions with natural organic matter in aquatic systems
• Grantee: Cláudia Hitomi Watanabe
• Support Opportunities: Scholarships in Brazil - Doctorate