Of Fireworks and Tourism: GC×GC-HRMS Analysis of Summer Impacts on Lake Michigan Water Quality

Significance of the Topic

The annual fireworks celebrations and accompanying influx of visitors can introduce a variety of chemical contaminants into freshwater ecosystems such as Lake Michigan. Assessing these short-term impacts is critical for environmental quality monitoring and informing mitigation strategies.

Objectives and Study Overview

This study aimed to characterize changes in Lake Michigan water composition before and after Independence Day fireworks events. Samples were collected at multiple shoreline locations on July 2nd and one hour post-fireworks on July 4th. Non-target screening was performed to identify both pyrotechnic residues and compounds derived from personal care products used by beachgoers.

Methodology and Instrumentation

Extraction Method:

• SPME Arrow with DVB/Carbon WR/PDMS phase
• Extraction: 30 min at 30 °C, stirring at 1200 rpm, pH adjusted to 2
• Desorption: 2 min at 270 °C

Chromatographic and Detection Conditions:

• GC×GC: LECO Quad-Jet Thermal modulator, Rxi-5ms primary and Rxi-17SilMS secondary columns
• Temperature program: 40 °C (2 min), ramp to 300 °C at 10 °C/min, hold 5 min; secondary oven +5 °C, modulator +15 °C offsets
• Carrier: Helium at 1.4 mL/min
• Detection: LECO Pegasus HRT+ TOF-MS, 40–520 m/z, 200 spectra/s

Key Results and Discussion

Non-target analysis revealed minimal direct fireworks byproducts but a pronounced rise in personal care compounds post-event. Notable observations included:

• Significant increases (up to 40x) in sunscreen actives such as homosalate, octocrylene, and oxybenzone
• Elevated levels of insect repellent DEET (5x) and fragrance components
• Emergence of compounds like δ-nonalactone and γ-dodecalactone linked to cosmetics
• Minor contributions from pyrotechnic-related species were below detection thresholds

High-resolution spectra with mass accuracies under 2 ppm facilitated confident identification of sulfur- and nitrogen-containing insecticide markers and oxygenated organic sunscreen ingredients.

Benefits and Practical Applications

By coupling SPME Arrow enrichment with GC×GC-HRTOFMS, laboratories gain:

• Enhanced sensitivity for semi-volatile and volatile organics
• Superior chromatographic resolution to resolve coeluting species
• Robust non-target screening for environmental monitoring

Future Trends and Potential Applications

Advances may include high-throughput automation, chemometric data mining for rapid pattern recognition, and extending the approach to other water bodies or sediment matrices. Integration with targeted quantitation can support regulatory compliance and risk assessment.

Conclusion

The combined use of SPME Arrow and GC×GC-HRTOFMS proved effective in detecting tourism-related chemical influxes, notably from personal care products, while fireworks residues remained below detectable levels. This workflow offers a powerful tool for comprehensive environmental surveillance.

References

Kelly CN, Richards TS, Binkley JE, Fell LM. Of Fireworks and Tourism: GC×GC-HRMS Analysis of Summer Impacts on Lake Michigan Water Quality. LECO Corporation.