Water quality and eutrophication status of the Zarivar Wetland (Iran)

Abstract

Wetlands are critically impacted by a variety of pollutants, primarily due to their position at the terminus of both surface and subsurface water flows. This study aims to assess the eutrophication status of Zarivar Wetland, situated in Kurdistan Province, Iran. To evaluate the eutrophication levels, the research employed the Iranian Water Quality Index for Surface Water Resources-Conventional Parameters (IRWQI_SC) and the Carlson’s Trophic State Index (TSI) during two sampling periods in July and September 2021. The findings indicate that in July, the wetland exhibited an upper-mesotrophic condition, with an average Carlson index value of 52.2, while in September, it transitioned to both upper-mesotrophic and eutrophic conditions, reflected by an average Carlson index value of 60.17. The zoned map of the eutrophication index identified domestic sewage from Marivan city as a significant contributor to elevated eutrophication levels in the southeastern region. Additionally, runoff from irrigated agricultural lands, orchards, and domestic wastewater from surrounding villages contributed to heightened eutrophication in the northeastern and eastern areas of the wetland. A comparative analysis of water quality between July and September 2021 revealed IRWQI_SC values ranging from 3.57 to 9.72 in July and from 2.63 to 4.72 in September, categorizing them as relatively good and good, respectively. To safeguard Zarivar Wetland, it is recommended to implement measures that prevent livestock waste discharge into the wetland, manage urban and rural sewage systems, control agricultural runoff, and optimize fertilizer application practices.