Assessment of Spatio-temporal variations in contamination, sediment and water quality index in Pasikhan River, Guilan Province

In recent years, the pollution rate of rivers entering the Anzali Lagoon has increased sharply due to population growth and industrial development. The purpose of this study was to investigate the pollution status and water quality index (WQI) in the Pasikhan River as one of the most important rivers entering the Anzali Lagoon.

This research was conducted at three hydrometric stations in the Pasikhan basin namely Mubarak Abad, Alisara and Noukhale within three years, 2014, 2015 and 2016. Sampling was carried out on a monthly basis and various parameters including sulfate, chloride, calcium, and bicarbonate were measured. Also, the WQI was used to quantify the overall quality of water. During the study, all the moral standards were observed.

The results showed that 81235 tons of suspended sediments were passed the Noukhale station annually entering the Anzali Lagoon. The values of chlorine at Noukhale, Mubarak abad, and Alisara stations were equal to 2.37, 0.18 and 0.18 mg/l, respectively. Based on the Wilcox diagram, the water resources were grouped as C1S1 and C2S1. The results of WQI revealed that the water status at all three stations was not favorable, which can be attributed to the discharge of municipal, industrial, and agricultural wastewaters into Pasikhan river.

In general, the results show that accumulation of sediments and pollutants transferred from the Pasikhan River to the Anzali Wetland increases the degradation of its ecosystem and also endangers human and fish health in the area.