From Challenge to Opportunity: Revolutionizing the Monitoring of Emerging Contaminants in Water with Advanced Sensors

The rapid industrialization and urbanization have led to a significant release of unregulated chemical and biological substances into the environment, referred to as emerging contaminants (ECs) (Pellegrin et al., 2015). These pollutants, which include pharmaceuticals (PHAs), personal care products (PCPs), endocrine disruptors (EDCs), industrial additives and agents (IAAs), surfactants and surfactant metabolites (SSMs), and other persistent organic compounds, originate from industrial, agricultural, and urban sources (Gavrilescu et al., 2015; Liu et al., 2023; Shahid et al., 2021; Zhao et al., 2024a). Present in concentrations from nanograms to micrograms per liter, ECs can persist, accumulate biologically, and pose risks to human health and ecosystems, with potential global spread due to their environmental toxicity (Naddeo. et al., 2013; Norvill et al., 2016). ECs are introduced into water environments through pathways such as residential, industrial, and medical wastewater, aquaculture, and stormwater runoff (Hills et al., 2011; Pal et al., 2014). Characterized by low concentrations and high stability due to properties like lipophilicity and hydrophobicity, these micropollutants accumulate and can adversely affect ecosystems and human health, including immune system damage, endocrine disruption, and increased cancer risk (Table 1) (Kumar et al., 2020; Liu et al., 2023).

Extensive academic literature on ECs details their classification, properties, and methods for removal from water bodies, with a focus on specialized remediation techniques such as physical methods (adsorption and filtration), chemical approaches (membrane technology, advanced oxidation processes, and sonochemical methods), and biological strategies (activated sludge, constructed wetlands) (Ensano et al., 2017; González-Alonso et al., 2017; Sarkar et al., 2019; Shahid et al., 2021). Although conventional methodologies for EC extraction and analysis are well-established, they are not suitable for the real-time monitoring of emerging contaminants in water due to their high costs, lengthy response times, and issues such as suboptimal recoveries and high percentage relative standard deviations (%RSD) (Table 2) (Cruz et al., 2012; Serna-Galvis et al., 2019; Serpone et al., 2017). Traditional monitoring techniques, including spectroscopy, chromatography, and biochemical tests, effectively target inorganic pollutants and specific high-risk organic contaminants but struggle to detect ECs due to their elusive and cumulatively toxic nature, thereby posing significant risks to public health and ecological safety (Kubitz et al., 1995; Liu et al., 2015; Martín-Pozo et al., 2019). Moreover, existing workflows that involve sample collection, pretreatment, and instrumental analysis face challenges due to the complex molecular structures and low concentrations of ECs such as endocrine disruptors and pharmaceutical residues, which often exceed the detection capabilities of conventional methods and are susceptible to cross-contamination during sample preparation (Figure 1) (Allan et al., 2006; Scheithauer and Uwe, 2013; Vilma et al., 2015). These limitations underscore the urgent need for technological advancements in the monitoring of ECs to ensure the safety and cleanliness of water environments (Leusch et al., 2014).

Considering these shortcomings, the urgency for novel integrated sensing and response monitoring technologies is clear. Innovations like sensors, nanotechnology, and online monitoring systems are pivotal for real-time water quality assessment and effective detection of and response to emerging contaminants (Yaroshenko et al., 2020). Biosensors, leveraging the high selectivity of specific biomolecules, excel in detecting pollutants in complex water matrices. Their high specificity and rapid response make them ideal for monitoring specific biomarkers in water environments (Yang et al., 2019). Nanomaterial-enhanced techniques in spectroscopy, chromatography, and electrochemistry offer heightened sensitivity and quicker response times. Certain nanoparticles, such as gold nanoparticles and carbon quantum dots, enhance chemical reaction signals, improving the detection of low-concentration pollutants (Takemura et al., 2022). Online monitoring systems, based on diverse sensors, offer immediate feedback on water environmental changes through continuous data collection and real-time analysis, facilitating prompt and comprehensive water quality monitoring (Teng et al., 2017). Integrated sensing and response monitoring technologies excel beyond traditional methods in terms of sensitivity, specificity, response time, and applicability. They are more capable of accurately detecting and identifying emerging contaminants in water, providing more effective solutions for water quality safety monitoring, which is a critical aspect of emergency response and water management.

Therefore, this review seeks to: (a) introduce various innovative integrated sensor monitoring technologies that combine both detection and response capabilities; (b) discuss the functional principles, advantages, and disadvantages of these sensor technologies in monitoring ECs; (c) help researchers select appropriate sensor types for various environmental scenarios, promoting the development of robust, deployable sensor solutions. The goal of this review is to assist in identifying the most suitable monitoring technologies for efficient EC detection under specific conditions, thereby aiding in their effective removal from water ecosystems.