The spatial and temporal distribution of the xenoestrogen nonylphenol and its potential ecological and health risks were assessed in the Karun River. A total of 120 water and sediment samples were obtained and analyzed from 10 stations (i.e. S1-S10) during two sampling campaigns in both dry and rainy seasons. The mean (±standard deviation) concentration of nonylphenol (NP) ranged from 0.139 (±0.022) to 2.288 (±0.305) μg/L in water samples and from 0.250 (±0.089) to 2.340 (±0.853) μg/g in sediment samples. Spatiotemporal variations of NP were observed, with the highest levels detected downstream of the Abadan and Ahvaz metropolitan areas during the rainy season. Similar trends were found between total organic carbon, nonylphenol polyethoxylates (NPnEOs) and NP. In contrast to the low total estrogenic equivalency quotient (EEQt ≤ 6.8×10 2 ) and acceptable hazard quotient (HQ ≤ 1.0) for all age groups, the ecological risk posed by NP was substantial. A high ecological risk quotient (RQ> 1) was found at all 10 sampling stations. The risk quotient peak was recorded at the nearshore area (S10) in the Persian Gulf (RQ=26.7). Therefore, the results indicate adverse effects on benthic organisms exposed to NP in the sediments of the Karun River, especially in downstream areas.
Teymouri et al. (2026) studied this question.