Impact of pollution on water quality in Algerian wetlands: a comparative assessment across multiple regions

Wetlands play a critical role in water purification and biodiversity maintenance, yet many are increasingly affected by anthropogenic pollution. This study provides a comparative assessment of physicochemical, microbiological, and heavy metal parameters in six Algerian wetlands spanning coastal, highland, and desert regions over a full annual cycle (November 2021-October 2022). Twenty-five indicators were measured across polluted and non-polluted sites. Polluted wetlands showed significantly higher turbidity (Z = - 3.678, p < 0.001), organic matter (Z = - 2.123, p = 0.04), and heavy metals including Cu (Z = - 4.234, p < 0.001), Fe (Z = - 3.123, p = 0.002), and Pb (Z = - 3.789, p < 0.001). Dissolved oxygen was consistently lower in polluted sites (Z = - 2.345, p = 0.02). Highland wetlands exhibited elevated nutrient loads, with nitrates (Z = - 2.789, p = 0.01) and ammonium (Z = - 3.123, p = 0.002) reflecting agricultural inputs. Microbiological contamination exceeded recommended thresholds at all polluted sites, with fecal coliforms and fecal streptococci surpassing 1000 CFU/100 ml. Seasonal analysis showed higher microbial loads in the wet season and concentration of nutrients in the dry season. Overall, the results demonstrate clear spatial and seasonal variation in water quality, with polluted sites across all regions exceeding national and WHO guideline values for nutrients, heavy metals, and microbiological indicators. These findings underscore the need for strengthened monitoring and pollution-control measures in Algerian wetlands.