A recent study demonstrated that hyperspectral imaging offers a highly accurate, dramatically faster alternative to traditional FT-IR methods for identifying microplastics in the Po River.
The Po River is a major European river system and a critical freshwater source for the area. Despite its importance, not many studies have documented the extent of microplastic (MP) pollution in the river. A recent study published in Talanta explored a new analytical protocol for polymer identification (1). This study, led by researcher Silvia Serranti of Sapienza University of Rome, monitored six stations across 300 kilometers of the Po River over a period of 12 months. The findings not only provide a detailed characterization of microplastic pollution in the basin, but they also validate hyperspectral imaging (HSI) as a highly efficient, reliable, and scalable alternative to traditional Fourier-transform infrared (FT-IR) and micro-FTIR spectroscopy.
The Po River is the longest river entirely in Italian territory, cutting through the city of Turin and leading out into the Adriatic Sea (2). Currently, there are growing concerns about the river’s viability to support over 20 million people (1). One of these concerns is related to drought, which is causing saltwater extensions and negatively impacting agriculture (2). Another is related to concerns about microplastics and other pollutants entering the water, which could have deleterious effects to human health.
In their study, the research team collected and analyzed 11,828 MP particles ranging in size from 330 µm to 5 mm. They assessed polymer composition, color, morphology, and abundance, creating one of the most comprehensive MP data sets for any river worldwide (1).
Their study’s findings revealed that MP concentrations in the Po River varied substantially across locations, ranging from 0.03 to 12.7 particles/m³, with the highest concentration observed at Chivasso and decreasing levels toward downstream sites such as Isola Sant’Antonio (1). These spatial trends likely reflect local pollution sources, land-use patterns, and hydrological characteristics of the basin. Notably, the Po River’s MP concentrations were lower than those reported in most major global rivers, offering a cautiously optimistic perspective on regional waste management efforts (1).
The majority of microplastics belonged to fragment (56%) and foam (24%) categories (1). This finding suggests that the majority of MPs originated from larger plastic items. Color analysis revealed that white particles dominated the samples (57%), reflecting the prevalence of weathered materials in surface waters (1).
Polymer analysis revealed that polyethylene (PE), polypropylene (PP), and expanded polystyrene (EPS) were the most common found in the samples. These three polymers accounted for 44.9%, 28.8%, and 22.5% of the sample, respectively (1).
The most notable aspect to this study was the role that HSI played in the study. Because of its analytical speed, using HSI only required 8 min per 100 particles, compared with 5 h using FT-IR) and 8 h using micro-FTIR (1). This drastic reduction in analysis time positions HSI as a powerful tool for real-time or large-scale monitoring efforts, which is an essential capability as environmental agencies worldwide seek faster, more cost-effective monitoring solutions (1).
Based on these outcomes, the authors propose a new HSI-centered analytical protocol for future MP monitoring campaigns. Under this scheme, HSI would serve as the primary method for polymer classification, while FTIR/micro-FTIR would be reserved exclusively for black MPs or particles that HSI cannot classify (1). This tiered approach enables rapid, scalable monitoring without sacrificing the accuracy required for regulatory and scientific applications.
“HSI technology has distinguished itself by its ability to analyze a large number of samples in significantly reduced time compared to traditional techniques, such as FTIR and micro-FTIR spectroscopy,” the authors wrote in their study (1). “HSI allowed for the precise and non-destructive identification of MPs ranging in size from 330 μm to 5 mm, demonstrating its efficiency in recognizing polymers with high accuracy, with discrepancies of less than 1% compared to the results of FT-IR spectroscopy.” (1)
By combining high accuracy with unparalleled speed, HSI offers a pathway toward more efficient long-term surveillance of freshwater ecosystems. As plastic pollution continues to challenge environmental health worldwide, the adoption of advanced technologies such as HSI may accelerate mitigation efforts and support more informed management of aquatic resources (1).
