DOI: 10.48457/iopan-2025-290
title: BaltiMTox Project: Ecotoxicity assessment of mixtures of micropollutants with emphasis on selected Baltic microorganisms

description: Emerging contaminants, including pharmaceuticals, are increasingly recognized as significant contributors to the degradation of freshwater, marine, and coastal ecosystems. The growing consumption of pharmaceuticals, driven by population growth and aging, combined with the inefficiencies of conventional wastewater treatment plants, has led to their widespread presence in aquatic environments. Coastal marine ecosystems, often considered the final sink for these residues, face particular risks. Similarly, ionic liquids (ILs), once hailed as “environment-friendly” alternatives to traditional solvents due to their unique physicochemical properties, are now identified as potential micropollutants. Their resistance to biodegradation and diverse industrial applications amplify their ecological impact.
Currently, most regulatory frameworks for environmental risk assessments focus on the effects of individual chemicals. However, ecosystems are often exposed to complex mixtures of pollutants, which can interact in ways that amplify risks or produce unforeseen consequences. To date, research has primarily concentrated on understanding the acute effects of these contaminants on freshwater ecosystems, with far less attention given to the chronic impacts on marine environments. This knowledge gap is particularly evident in understanding the ecotoxicological impacts of pharmaceuticals and ionic liquids on marine phytoplankton—essential primary producers whose disruption can propagate through trophic levels.
 Phytoplankton species, which play essential roles in oxygen production and biogeochemical cycling, exhibit variable sensitivities to pollution. Altering their populations can disrupt ecosystem balance, affecting food webs and overall productivity. The Baltic Sea, a shallow, semi-enclosed marine environment with a dense human population and intense agricultural and industrial activities, is particularly vulnerable. It serves as an ideal case study for examining the impacts of emerging micropollutants on marine communities.
 This project addresses these knowledge gaps by investigating the long-term effects of low concentrations of pharmaceuticals and ionic liquids, individually and in mixtures, on representative species of Baltic microalgae and cyanobacteria. By focusing on key physiological processes, such as photosynthesis, photoprotection, and antioxidant responses, this research provides valuable insights into the underlying mechanisms of toxicity. The findings are instrumental in modeling phytoplankton community structure and ecosystem function under pollutant stress, shedding light on the broader implications for ecosystem health and resilience.
 Given the Baltic Sea’s vulnerability and the critical ecological roles of its phytoplankton, this research emphasizes the urgent need for comprehensive studies on emerging micropollutants. By exploring their impacts on marine communities, this work contributes to our understanding of bottom-up ecosystem degradation and supports the development of more effective regulatory strategies to mitigate these threats.

Keywords for CSV files:

Chlorophyll fluorescence parameters:
A01 - Fv/Fm: the maximum quantum efficiency of photosystem II (Fm -the maximum fluorescence, Fv- variable fluorescence)
A02 - ABS/RC: The absorption flux per reaction center (RC)
A03 - ETo/RC: Electron transport rate per reaction center (RC)
A04 - DIo/RC: The energy dissipation per reaction center (RC)

Oxidative stress parameters:
B01 - T-SOD activity (U/mL): Total superoxide dismutase (T-SOD) activity measured in units per milliliter of a sample
B02 - mg protein/mL: the concentration of protein in a sample, measured in milligrams of protein per milliliter (mg/mL)
B03 - U/mg protein/mL: activity (in units) per milligram of protein per milliliter (enzyme activity normalized by protein concentration in the sample)

Growth changes parameters:
C01 - Optical density 680nm: optical density at wavelength 680nm

Pigment content: 
D01- C [ng/dm3]: concentration measured in nanograms (ng) per cubic decimeter (dm³)
D02 - PE/chla-a [x10-8]: the ratio of phycobilins (phycocyanin or phycoerythrin) to chlorophyll-a multiplied by 10-8
D03- PE/chla-a [x10-5]: the ratio of phycobilins (phycocyanin or phycoerythrin) to chlorophyll-a multiplied by 10-5
D04 - PE/chla-a [x10-6] : the ratio of phycobilins (phycocyanin or phycoerythrin) to chlorophyll-a multiplied by 10-6
D05 – C [µg/dm³]: pigment concertation in micrograms per cubic decimeter
D06- pigment/chl-a: ratio of the pigment’s concentration and chlorophyll-a content 

Standard parameters:
M01 – ± SD: standard deviation 
M02- ± SD [x10-9] : standard deviation value multiplied by 10-9
M03- ±SD x [10-1]: standard deviation value multiplied by 10-1
M04- ± SD [x10-3]: standard deviation value multiplied by 10-3
M05 – C %: percent of the control 
M06 – Average: the average value (n=3) 
M07 – inhibition_ratio_i : the inhibition ratio relative to control 
M01A01 - ± SD: standard deviation for A01 (Fv/Fm)
M01A02 - ± SD: standard deviation for A02 (ABS/RC)
M01A03 - ± SD: standard deviation for A03 (ETo/RC)
M01A04 - ± SD: standard deviation for A04 (DIo/RC)