How Light Helps Detect Detrimental Environmental Chemicals

Light is more than just something we see; it's a powerful tool for studying the invisible. In environmental science, light-based methods have become essential for detecting harmful substances in air, soil, and water. These techniques help scientists and technicians locate chemicals that could pose health risks, even in very small amounts.

From ultraviolet light to infrared and laser-based systems, each approach reveals something different about a substance's composition. As pollution and industrial waste continue to raise concerns, these tools are helping researchers get faster, more accurate results.

In this article, we will discuss how light can help detect harmful environmental chemicals.

Light as a Diagnostic Tool for Chemical Detection

Each chemical interacts with light in its own way. Some absorb it, some reflect it, and others scatter it. These unique responses are what make optical tools so valuable. Light can help identify a chemical based on its behavior when exposed to certain wavelengths.

For example, if a compound, it can suggest the presence of specific bonds, such as those found in organic solvents or pesticides. As stated in an MDPI study, most light sources currently used for pesticide detection are white light. The study highlights how light detects cypermethrin, the most commonly used pesticide in Shanghaiqing. It primarily contains the following bonds:

• C-Cl
• C=C
• -CN
• C=O
• C-O-C
• -C6H5

The absorption positions and intensities vary based on the type of bond present in the pesticides. This interaction helps pinpoint what's in a sample, whether from river water, factory runoff, or even air near an industrial site.

Spectroscopy: Breaking Down Light to Reveal Chemicals

Spectroscopy is one of the most widely used methods in environmental testing. It works by shining light onto a sample and measuring how it is absorbed, emitted, or scattered. Different types of spectroscopy, like UV-visible, infrared, or Raman, are selected based on tasks.

For instance, Triboelectric Spectroscopy (TES) is one way to do chemical analysis in water. This technique can detect over 30 types of common salts, organic molecules, acids, and bases with 93% accuracy. Thus, it can be used for real-time monitoring across various geology, chemistry, environment, and biology applications.

Spectroscopy can be used to determine various pollutants in water and soil. Consider the example of Per- and Poly-fluoroalkyl Substances (PFAS). Some PFAS chemicals like perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) are known to be carcinogenic.

These chemicals are primarily found in aqueous film-forming foam (AFFF). Thus, using AFFF near water bodies or disposing of it inappropriately can lead to water and soil pollution. Moreover, TorHoerman Law states that exposure to these carcinogens can also lead to numerous types of cancer. Many firefighters and Air Force individuals who use AFFF have already developed cancers.

Spectroscopic testing can be key in tracing PFAS in water sources near airports, military bases, and fire training sites. This can help create scientific evidence linking cancers in people exposed to the chemicals and help them in firefighter foam lawsuits. It can provide conclusive evidence in the ruling of a firefighter foam lawsuit. Thus, plaintiffs can use it to seek appropriate compensation for the problems they have suffered.

Remote Sensing: Detecting Chemicals Without Contact

Light can also be used in remote sensing, which allows scientists to detect chemicals from a distance. This is useful in large or dangerous areas, such as oil spills, chemical plants, or contaminated fields. Instruments mounted on satellites or aircraft can scan the area and pick up signs of pollutants based on how they reflect or absorb light.

This technique is especially valuable in emergencies, where time is limited, and conditions may not be safe for manual sampling. According to the US Geological Survey (USGS), remote sensing can also be used for many other applications, such as:

• Mapping large forest fires
• Predicting weather based on cloud movements
• Tracking a city's growth and changes in farmland
• Discovering and mapping the ocean floor's rugged topography

Laser-Induced Breakdown Spectroscopy (LIBS) for Soil Testing

Laser-induced breakdown spectroscopy (LIBS) is becoming more common in soil analysis. This technique produces a small plasma on a sample's surface using a brief, intense laser pulse. The light emitted by the plasma can then be analyzed to identify the elements present.

LIBS is useful in fieldwork because it doesn't require chemical reagents and can deliver immediate results. It helps detect heavy metals like lead, arsenic, and mercury, which is especially important near mines, industrial zones, or areas with known contamination.

Fluorescence Techniques for Oil and Chemical Spills

Fluorescence-based techniques are often used to track hydrocarbons, such as those found in oil. When exposed to ultraviolet light, many petroleum-based chemicals fluoresce, emitting visible light. This makes them easier to locate on water surfaces after a spill.

These methods are helpful for quick assessments during emergencies. Responders dealing with oil leaks can shine UV light over the water to spot the spread of the oil.

Frequently Asked Questions

Can light-based technologies detect biological contaminants like bacteria or viruses in the environment?

Light-based tools are better suited for detecting chemical substances than biological organisms. However, certain optical methods, like fluorescence microscopy or laser scattering, can help identify microbial presence. This can be done by detecting the by-products or specific markers associated with bacteria or viruses.

Are light-based detection tools safe to use in the environment?

Yes, most of these tools are non-destructive and safe. Techniques like spectroscopy and fluorescence don't require adding chemicals or altering the sample area. Some high-powered lasers used in methods like LIBS are more intense. However, they affect only tiny sample areas and are typically used under controlled conditions.

How do light-based methods compare to traditional chemical testing?

Traditional testing often involves collecting samples and using reagents in a lab setting, which can be accurate but time-consuming. On the other hand, light-based methods can deliver faster results, often without complex sample preparation. While traditional methods are still widely used, light-based tools are gaining popularity for real-time analysis.

As the push for cleaner environments continues, light-based detection systems will likely play an even larger role. Their precision, speed, and ability to work across various conditions make them reliable tools for scientists and policymakers.

Whether used in the lab or the field, these technologies offer a clear advantage in the early detection and ongoing monitoring of hazardous chemicals. They support efforts to keep communities safe, ecosystems balanced, and industrial impacts under control.