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The title of the thesis: Exploring spectroscopic methods for environmental monitoring

Thesis defender: Sudatta Das
Opponent: Prof. Carla Vogt, Technical University Bergakademie Freiberg, Germany
Custos: Prof. Erkki Ikonen, Aalto University School of Electrical Engineering

Our environment is increasingly burdened by pollution, some visible, much of it invisible. Among the most harmful forms are trace metals and microplastics. Though present in very small amounts and complex matrices, they pose serious risks to ecosystems and human health.

Trace metals enter water through industrial discharge, mining, and poor waste management. Even at low concentrations, they can accumulate in living organisms and lead to chronic toxicity. Monitoring them is not just a scientific need but a regulatory one.

Microplastics (plastic particles under 5 mm) come from cosmetics, textiles, packaging, and degraded plastic waste. They are found in water, soil, and air. Unlike traditional pollutants, microplastics don’t degrade easily and may carry other harmful substances.

Detecting these contaminants requires not only precision but also accessibility, affordability, and real-time capabilities. Traditional detection methods like ICP-MS (for metals) and FTIR (for plastics) are accurate but expensive, time-consuming, and lab-bound.

My research addresses this gap between lab-based techniques and real-world application. The thesis is divided into two parts:

Part I: Micro-plasma Based Trace Metal Analyzer
I studied micro-plasma emission spectroscopy as a portable, real-time alternative for metal detection. Key advantages include sensitivity, stability, portability, and speed. My results show that this system is a reliable tool for rapid assessment, supporting decisions in environmental monitoring, industrial safety.

Part II: Photoacoustic Detection of Microplastics
This part explores photoacoustic spectroscopy (PAS) as a non-destructive technique for identifying microplastics under simulated environmental conditions. PAS uses sound waves generated by light absorption to analyze materials. I studied various polymer types and compared PAS data with FTIR results to validate performance.

Significance
My thesis contributes to practical environmental analysis through:

   A portable analyzer for trace metals

   Foundational research on PAS for microplastics

   Method validation to support scientific and regulatory use

The novelty lies in making advanced detection tools both practical and scalable, bridging lab research and field application.

Keywords: environmental monitoring, industrial application, trace metal analysis, photo acoustic spectroscopy, microplastic analysis.

Thesis available for public display 10 days prior to the defence at .