Toxic metals in AQUAtic systems: SMART in-situ sampling and real-time monitoring

The main objective of this proposal is to devise an integrated smart sampling and automatic monitoring of toxic metal ions in aquatic systems. Their adverse effects are well documented, notably for those displaying toxic, carcinogenic, mutagenic and teratogenic effects for living organisms [1,2] like lead, cadmium, mercury, arsenic and chromium, but also for zinc, iron and copper that may present adverse effects if present in high concentrations. In aquatic systems, they can be present in different forms, namely by the chelation of their metal ions with inorganic or organic ligands, making their toxicity dependent on the respective form. Another concern with these elements is due to their non-biodegradable nature and consequently potential entry in the food chain [3–6]. Moreover, recent works point out that their presence can also promote microbial virulence and antibiotic resistance [7].
As water bodies are dynamic systems, the presence of these ions must be a target of spatial-temporal monitoring. The real-time monitoring is rather cumbersome as current methods rely on transport to off-site laboratories, causing the disruption of the sample characteristics, due to pH and redox potential change and exposure to oxygen, light or temperature shifts, leading to diverse chemical equilibria shifts.
To overcome this limitation, we propose to devise new smart sampling procedures and also flow-based monitoring. The idea is to use surface chemistry approaches, for which we intend to:
1)Develop polymer inclusion membranes (PIMs) [8,9] to selectively collect the analytes at the source - smart passive sampling. This way, this liquid polymer membrane will be deployed on site to pre-concentrate the analyte, by liquid-liquid micro-extraction for as long as needed; then the analyte can be measured through the inclusion of the membrane in a flow system, cited below;
2)Devise microtubes (cartridges-like tubes) packed with novel sorbents (SPE) to collect the samples. These can be moved to specific sampling points and can be even used in onboard campaigns. The sorbent material can be enriched with analytes by perfusing the sampling device with a large water volume, along with interferents removal; then, the enriched plug is eluted for measurement;
3) For analysis, we propose to use flow-based devices [10] with miniaturized optical detection to make the apparatus a portable equipment.
So, the whole process, sampling/preparation/measurement, will become automated. This way, it will allow the real-time monitoring of various metal species in water bodies. This approach is innovative, both in Analytical Chemistry and Environmental Monitoring, as only automation of the measurement has been a central subject of investigation.
These novel approaches will be applied to aquatic systems in Northwestern Portugal, at locations where the ICBAS/UP participant already carries out periodical sampling campaigns and analysis. The results will be compared with the established reference methodologies.