Monitor River And Lake Ecosystems Using Spectrometers

INTRODUCTION

The growing need for water, food, and energy necessitates a better understanding of freshwater ecosystem processes and their sustainable management. Freshwater is crucial for human survival and contributes to global water security, food production, and economic activity. These ecosystems, especially which can be found in lakes and rivers, provide a wide range of services such as drinking water, energy, transportation, recreational activities, and vital roles in biodiversity and ecological functions such as nutrient cycling. However, growing pressure from human activity, climate change, and population increase endangers biodiversity and ecosystem health, particularly since freshwater systems are very vulnerable to environmental degradation. Despite occupying only a small percentage of the Earth's surface, freshwater ecosystems contain enormous biodiversity, making them vital to global ecological balance; nonetheless, they experience the highest rates of biodiversity loss. With so many people relying on the benefits of rivers, monitoring river and lake ecosystems is critical for managing water resources, ensuring biodiversity, and assessing environmental changes. Scientists are employing technologies like spectroscopy to monitor the stability and health of the flowing water and its surroundings.

METHOD

The method of using spectrometers to monitor river and lake ecosystems relies on detecting light wavelengths reflected or absorbed by the water. Different water characteristics, such as organic matter, nutrients, and pollutants, interact with light in unique ways, allowing spectrometers to quantify these parameters.
Numerous studies have documented the use of ground-based UV-VIS spectroscopic devices for remote, long-term water quality monitoring. UV-Vis spectroscopy uses ultraviolet (200–400 nm) and visible light (400–700 nm) to analyze water, UV and visible light are passed through or reflected from the water, different substances absorb light at specific wavelengths based on their molecular composition and concentration.
The absorption of specific light wavelengths by various compounds in the water allows for the quantification of key ecosystem parameters related to ecosystem health include Nitrates, Phosphate concentrations, DOM (dissolved organic matter), Chlorophyll, COD (Chemical Oxygen Demand), etc.

RESULTS

Figure 3. Chlorophyll a concentrations (mg/L) in lake water samples. The water samples were collected at three spots, and differences in the concentrations of chlorophyll a were measured using a modular spectrometer configured for absorbance. OD: optical density. Courtesy of Yvette Mattley.

Figure 3 demonstrates the concentration of chlorophyll a in three samples collected at three different spots on the lake surface with absorbance spectrums, peak 440nm inform the presentation of Chlorophyll a in samples. The difference in three samples spectrum revealed a difference concentration, which is affected by variations in water temperature, solar exposure, and nutrient concentration. Similar experiments can be done in river waters where the concentration of chlorophyll varies according to residence time (the amount of time a chemical spends in the water), river flow, and other factors.

Figure 4. The UV absorbance of surface water samples captured using a portable UV-VIS spectrometer. Signal intensities differ between the lake water, ground snow, and snow runoff. The presence of contaminants may be indicated by strong absorbance in the UV range. The samples were collected at Mt. Spokane, Wash. Courtesy of Derek Guenther.

Another experiment presented snow with a solar-powered system to measure the reflectance. The goal is to detect spectral evidence of dust, black carbon, and algae, which can influence the rate of snow melting, the chemical properties of runoff, and the eutrophication (nutrient and mineral buildup) of water after it flows into nearby mountain streams and rivers. Results in Figure 4 indicate the presence of particles in different samples due to the absorbance on peak 210nm, contaminants in Florida Lake Water is much higher than two other samples.

EQUIPMENT

Spectrometers for monitoring:
Multiwavelength detector is spectrometers can determine the concentration of some specific water factors (UV254, nitrate) through absorbance of selected wavelength. QEPro High-Performance Spectrometer is suitable equipment for measuring with large dynamic range (85000) can detect both very low and very high signal levels, making it versatile for monitoring diverse water quality parameters, broad wavelength range to cover from 200 nm to 1100 nm, enabling the detection of a wide range of water quality indicators, from ultraviolet (UV) to visible light, crucial for analyzing substances like nutrients, organic matter, and pollutants. Besides that, optical resolution of QEPro approximately 1.2 nm FWHM ensures detailed spectral analysis, which helps in distinguishing between closely spaced absorption features in complex water samples. These features collectively make the QEPro an excellent choice for detailed and accurate monitoring of aquatic ecosystems, providing critical insights into water quality and ecosystem health

Figure 1. QEPro High-Performance Spectrometer

Light sources for UV-Vis spectroscopy
Light sources choosing based on main requirements such as suitable spectrum, Intensity, Stability, Lifetime, etc. Here we recommend the UV-LIS-NIR DH-2000 light source for illumination use xenon, deuterium and tungsten halogen to cover various wavelength segments from 200-2500 nm, which can be use on multiple applications such as absorbance, transmission, reflectance, etc.

Figure 2. UV-VIS-NIR light source

Besides that, INTINS also provides additional items and accessories to complement and enhance the measurement system. By offering a comprehensive range of tools, INTINS ensures that users can customize and tailor water quality monitoring systems to achieve more accurate and efficient results in real-time ecosystem assessments.

CONCLUSION

Monitoring river and lake ecosystems with spectrometers, particularly UV-Vis spectroscopy, is a potent, non-invasive technique to understanding and conserving these vital water resources. Spectrometers can reliably detect essential water quality indices in real time by measuring how compounds in the water absorb specific wavelengths of light, such as nutrient levels, dissolved organic matter, and contaminants. This technology provides a rapid, reagent-free alternative for large-scale, continuous ecosystem monitoring, allowing for more effective management of freshwater resources. As human activities and climate change pose new threats to aquatic ecosystems, spectrometry will play an increasingly important role in protecting biodiversity and guaranteeing long-term water quality.