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July 23, 2025
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November 15, 2025
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December 1, 2025
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Abstract

The current study aims to address the environmental challenge of nutrient enrichment in freshwater ecosystems, particularly in the Tigris River, by providing a comprehensive assessment of nutrient concentrations, including sulfates (SO₄²⁻), nitrites (NO₂⁻), nitrates (NO₃⁻), ammonium (NH₄⁺), and phosphates (PO₄³⁻), evaluating the temporal and spatial distribution, and identifying the most important human -based activities contributing to the load of nutrient. Samples were collected from six sites distributed along the river within Baghdad city, over a three-year period (2020–2022). The results showed a clear spatial variation, with concentrations of most nutrients gradually rising towards southern sites, indicating the impact of accumulated human activities such as sewage, industrial discharges, and agricultural runoff. Nitrates and phosphates were highest at sites near dense urban and industrial areas, while nitrite concentrations were generally low but appeared to be an indicator of incomplete biological activity. Sulfate concentrations (211–233 mg/L) exceed the environmental limits allowed under the 1967 Iraqi River Maintenance Regulation, and show a need for better water management and regular monitoring. In terms of time, the data showed significant annual changes in nutrient concentrations, with an increase in sulfate and phosphate concentrations recorded in 2022 and 2021, respectively, compared to previous years, which may reflect an increase in untreated discharges or the effects of drought and reduced river flow. In contrast, nitrate concentrations declined sharply in 2021 and rose again in 2022. Nitrite and ammonia concentrations remained relatively stable over the three years. The research recommends the need to strengthen continuous environmental monitoring systems, update national laws to include nutrient pollutants such as nitrite, and enhance the efficiency of water treatment plants, with the aim of reducing eutrophication and protecting the river ecosystem.

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