Distribution and Ecological Risk Assessment of Linear Alkylbenzene Sulphonates (LASs) in Anzali International Wetland

Abstract

Background & objectives: LAS is a major component of household and industrial detergents, which has caused many problems in the biological and non-biological sectors during the last decade due to the discharge of raw urban sewage into aquatic ecosystems. Considering the importance of this issue, the present study examines the concentration, distribution and evaluation of the ecological risk of this pollutant in the Anzali International Wetland. Methods: 50 stations from Anzali wetland water were selected for sampling. After measuring some water qualitative factors such as temperature, acidity, electrical conductivity and dissolved oxygen at the sampling site, samples were transferred to the laboratory and analysis and extraction of samples was performed using Methylene Blue method. Statistical analysis was performed using SPSS-22 software, pollution concentration zoning map using the conventional kriging method in ArcGIS 10.3 software and LAS risk estimation calculations using RQ formula in Excel software. Results: Based on research findings, LAS concentration was in the range of 0.01-3.93 mg/L. The highest concentration of LAS was observed in stations of central and eastern part of the wetland and the lowest concentrations in western and Siyah Kashim stations. The results of calculating the risk assessment (RQ) and the zoning of this pollutant showed a higher risk in many areas of the wetlands. Conclusion: Considering the high concentrations of LAS in most areas of Anzali Wetland, it is necessary to pay more attention to management of urban wastewaters discharge and treatment of municipal wastewater of Anzali port and its adjacent areas and to control the entry of raw wastes into the wetland.