Toxic metal pollution in freshwater ecosystems: A systematic review of assessment methods using environmental and statistical indices

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#water-pollutants-chemical #environmental-monitoring #fresh-water #ecosystem #metals

Toxic metal pollution in freshwater ecosystems: A systematic review of assessment methods using environmental and statistical indices

Kanwel et al., 2025 | Mar Pollut Bull | Systematic Review

Citation

Kanwel Shahida, Gulzar Fatima, ... Jing Hua. Toxic metal pollution in freshwater ecosystems: A systematic review of assessment methods using environmental and statistical indices. Mar Pollut Bull. 2025-Sep;218:118028. doi:10.1016/j.marpolbul.2025.118028

Abstract

Surface sediments play a crucial role in freshwater ecosystems as sinks for harmful pollutants and indicators of aquatic health. While localized studies have provided insights into pollution levels, a global assessment of freshwater sediments has been lacking. This study addresses this gap by analyzing data from 149 freshwater sites across 32 nations using multivariate statistical methods (PCA and NMDS were used; receptor models such as PMF, APC-MLR, and UNMIX were not applicable due to lack of primary raw data) and established environmental indicators. Results revealed that average metal concentrations, except for cobalt and zinc, exceeded safety standards, with arsenic, cadmium, and mercury being the most prominent contaminants. Severe contamination was observed in 29-69 % of locations, with arsenic, cadmium, chromium, and nickel posing significant risks to aquatic life in 4-31 % of sites. The ecological risk index (CSI > 5, RI ∼ 600) indicated that 65 % of sites face severe environmental threats. Advanced statistical analyses, including principal component analysis and non-metric multidimensional scaling, identified pollution patterns and sources. Four principal components explained 89 % of the variance, with strong linear correlations (R2 = 0.93) and minimal ordination stress (Stress = 0.023), ensuring the reliability of findings. Source enrichment analysis linked contamination to both natural and human activities, including agriculture, mining, industry, municipal wastewater, and fossil fuel emissions. These findings highlight the urgent need for effective sediment contamination management in freshwater ecosystems.

Key Findings

These findings highlight the urgent need for effective sediment contamination management in freshwater ecosystems.

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition stress

MeSH Terms

  • Water Pollutants, Chemical
  • Environmental Monitoring
  • Fresh Water
  • Ecosystem
  • Metals
  • Geologic Sediments
  • Metals, Heavy

Evidence Classification

  • Level: Systematic Review
  • Publication Types: Journal Article, Systematic Review
  • Vertical: chromium

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09