Assessing the level of human impact (anthropization) on hydrosystems and understanding how the dynamics of micropollutant concentrations, their bioavailability, and their combined effects (“cocktail effects”) are integrated and redistributed across major hydro-biogeochemical cycles are key scientific challenges — where technology plays a central role. Specifically, characterizing and quantifying the mechanisms controlling micropollutant cycles and fluxes in relation to human activities is essential for better evaluating ecotoxicological responses and long-term impacts on biodiversity.

As part of TERRA FORMA, several samplers are being studied :

• The THOE-LITE integrative-passive sampler is a low-cost, connected version of the automated in situ THOE platform produced by AEL-Technicap. It embeds 12 passive sensors of the DGT (Diffusive Gradient in Thin films) type for sequential monitoring, originally developed for deep-sea oceanographic applications (up to 1000 m depth).

• The TRACESENSE integrative-dynamic contaminant sampler builds upon previous instrumentation research at GET, which led to a patented prototype by IRD (WO2016128686). The aim is to miniaturize the device to diversify its in situ monitoring applications :
  (i) performing near-instantaneous horizontal and/or vertical profiling in lakes, rivers, piezometers, or groundwater (e.g., karst systems) ;
  (ii) enabling, once integrated into the THOE platform, higher frequency monitoring during short-term events such as flood peaks ;
  (iii) better parameterizing diffusion processes at the water/sensor interface.
  This technology, based on in situ dynamic vibration of complexing substrates similar to those used in DGTs, enables a 30- to 50-fold reduction in integration time for monitoring contaminants such as mercury. Alternatively, it allows for the preconcentration of larger amounts of target analytes/molecules, thereby lowering detection limits. It can be applied to many other trace elements and organic compounds, provided that suitable complexing or adsorbing gels are available. These fast samplers allow higher-frequency monitoring (every few hours), as compared to passive samplers (several days), and can also enable vertical or horizontal gradient monitoring when deployed across groundwater zones.

• Specific and broad-spectrum passive samplers of the DGT type, including :
  (i) new complexing resins for highly specific monitoring of selected trace elements, organometallic compounds, or organic molecules ;
  (ii) exploration of combinations of multiple complexing resins and/or adsorbing substrates to broaden monitoring capabilities.

Combining these different types of samplers will complement traditional water quality monitoring programs, which typically rely on classical sampling methods (e.g., grab sampling of surface water, groundwater sampling through instantaneous pumping, or vertical profiling using sampling bottles). Such methods are poorly adapted to capturing how micropollutants permeate hydrosystems and their fate in the environment. The subsequent laboratory analyses of these integrated samples will improve our understanding of pollutant concentration levels during highly variable pollution events that can change on hourly (e.g., flood peaks), daily (biological and photochemical cycles), or sub-seasonal (hydrological, biogeochemical, or land-use cycles) timescales.

Theme : Water Resources, Pollution

Updated on 23 juin 2025