Toxicity of microplastics, graphene quantum dots and molybdenum disulfide to the freshwater organism Daphnia magna

Hayat Davoudi, Hossein ORCID: 0000-0001-5652-010X (2023). Toxicity of microplastics, graphene quantum dots and molybdenum disulfide to the freshwater organism Daphnia magna. University of Birmingham. Ph.D.

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Abstract

Production and use of engineered nanomaterials (ENMs) in consumer products has significantly increased in the last decades due to their unique characteristics. This results in ENMs being released into the environment and interacting with living organisms. In parallel, the increase in plastic use worldwide leads to their breakdown into micro (MPs) and nano plastics (NPPs), further increasing environmental particle burdens. A key question addressed in this thesis is whether particles of very different characteristics affect aquatic organisms in a similar manner. Polystyrene (PS) is a popular representative of MPs/NPPs widely used in many applications. Graphene quantum dots (GQDs) and molybdenum disulfide (MoS2) are recently emerged ENMs, used in a wide range of applications. Daphnia magna (D. magna) is an important freshwater environmental indicator for toxicity assessments. The toxicity of PS, GQDs and MoS2 towards D. magna was assessed, considering factors controlling their physicochemical properties and toxicity, to address literature gaps. The toxicity of particles mainly depended on their size (smaller > larger), surface charge (+ve > -ve), ageing, chemical additives, and the composition of dispersant solutions. Applying environmentally relevant conditions greatly reduced the toxicity of the NMs relative to standardized test medium, suggesting the need for updating of regulatory test guidelines.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):