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Model Construction and Prediction of Combined Toxicity of Arsenic(V) and Lead(II) on Chlamydomonas reinhardtii
by
, and
Zhongquan Jiang
1,2,3
,
Tianyi Wei
3, 
Chunhua Zhang
4,
Xiaosheng Shen
1,*,
Zhemin Shen
3,
Tao Yuan
3 and
Ying Ge
2,* 1
East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai 200090, China
2
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
3
State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
4
Laboratory Centre of Life Science, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China
*
Authors to whom correspondence should be addressed.
Biology 2025, 14(10), 1395; https://doi.org/10.3390/biology14101395 (registering DOI)
Submission received: 12 September 2025
/
Revised: 3 October 2025
/
Accepted: 10 October 2025
/
Published: 11 October 2025
(This article belongs to the Section Toxicology)
Simple Summary
Arsenic and lead, toxic metal and metalloid from industry and agriculture, often pollute water together and harm aquatic life, but we do not fully understand how they act together. We looked at how these metals affect the growth of a common algae called Chlamydomonas reinhardtii under laboratory conditions and used models to predict their combined harm. We found arsenic(V) is much more toxic than lead(II), and as arsenic levels rise in mixtures, the two metals go from acting together to being more harmful than expected. Under the environmentally relevant ratio of As:Pb = 1:10, the mix badly damages algae cells. These findings help us better assess water pollution risks and create better strategies to protect aquatic ecosystems and human health.
Abstract
With the acceleration of industrialization, the impact of the toxic metalloid arsenic (As) and metal lead (Pb) on aquatic ecosystems has garnered widespread concern. However, the specific toxic effects of how these two metals jointly impact aquatic organisms are not yet fully understood. This study aims to investigate the toxic effects of As and Pb individually and in combination of the mixture on the growth of Chlamydomonas reinhardtii (C. reinhardtii) in a lab setup using the Concentration Addition (CA) model and the Independent Action (IA) model to predict the toxic effects at different concentrations. The results indicated that As and Pb had significant inhibitory effects on the growth of algae, and the toxicity of As was greater than that of Pb (As EC50 = 374.87 μg/L, Pb EC50 = 19988.75 μg/L), measured by Spectrophotometer. As the metal concentrations increased, both metals demonstrated classic sigmoidal concentration-effect curves. Furthermore, we discovered that in mixtures of As and Pb at varying concentration ratios, the combined toxic effect shifted from additive to synergistic with increasing As concentration, exhibiting a pronounced concentration ratio dependency. Utilizing nonlinear least squares regression, we successfully constructed concentration-response models for both As and Pb, employing Observation-based Confidence Intervals (OCIs) to reflect the uncertainty of the data. By comparing experimental data with model predictions, the EC50 was used as an index to compare the toxicity magnitude of As/Pb mixtures. The toxicity of As and Pb mixtures gradually increases with the increase in their concentration ratios. Scanning and transmission electron microscopic observations revealed that the combination of 200 μg/L As and 2000 μg/L Pb resulted in the greatest synergistic toxic effect, with severe breakage and indentation to C. reinhardtii cells. This study not only provided new insights into the environmental behavior and ecological risks of As and Pb but also held significant implications for effective water pollution management strategies by offering a validated model-based framework for predicting mixture toxicity across different concentration regimes.
