Seasonal changes in water quality properties at a part of the Euphrates River in Al-Najaf Governorate, Iraq

ABSTRACT Graphical abstract showing the effect of local climate and anthropogenic pressure on key water physicochemical properties. Freshwater provides significant ecosystem services, but natural and anthropogenic activities can negatively affect these services by affecting water quality properties (WQPs). The present study focuses on a section of the Euphrates River in Al-Najaf, Iraq, over a 10-month period (December 2018–September 2019) to evaluate whether the water quality complies with the standards for recreational and drinking water safety under local hydrological conditions. A waterproof multimeter and atomic absorption spectroscopy were used to measure some of the main physicochemical variables (total dissolved solids (TDS), electrical conductivity, salinity, sulfate, phosphate, nitrate, and heavy metals), with Gram-negative bacteria counted. Gram-negative bacteria and sulfates exceeding World Health Organization (WHO) guideline limits suggest potential fecal contamination and treatment failure, increasing the risk of waterborne infections. Furthermore, heavy metal concentrations were up to twice the WHO limits on specific sampling dates. WQPs varied significantly over time (p 0.05), following a seasonal trend and becoming unhealthy as they deviated from WHO guidelines, as follows: winter spring summer. An increase in TDS, sulfate, and heavy metal concentrations in winter may reflect a potential increase in wastewater discharge. The results highlight the impact of local climate and the effects of upstream dams on water quality.