Biomonitoring, simulation, and evaluation of anthropogenic pollution in Disam River, Iran: use of macro-invertebrates based biotic indices and Qual2kw model

Abstract

Abstract This study evaluates the water quality and self-purification status of the Disam River through biotic indices of macro-invertebrates and mathematical modeling (Qual2kw). A total of 10,370 macro-invertebrates were collected by a Surber sampler at five sample points from 2019 to 2020. Based on HFBI and ASPT, stations 2 and 3 were categorized in "Moderate" and "Very poor" classes and the EPT categorized the river as "Good", while the BMWP classified it as" Acceptable". Canonical correspondence analysis (CCA) was employed to elucidate the relationships between biotic indices and physicochemical parameters. The EPT displayed a positive correlation (axis1 = 1/43, axis2 = 0.065) with most of the physicochemical parameters of the Qual2kw. The results of comparing the output of the Qual2kw with the occurrence of the macro-invertebrates show that the Chironomidae family had the most dominance (S2 = 37.66% and S3 = 47.33%) in all seasons (except summer), while in summer, the Baetidae showed the most occurrence in S2(79%) and S3(78%) and has a positive Coefficient with temperature rise(r = 0.21) and velocity reduction(r = 0.053). The analysis of BOD and DO curve data showed that the process of self-purification is carried out along Disam River. These findings highlight the importance of the simultaneous study of biotic indices and mathematical modeling of the physicochemical parameters to assess the “ecological integrity” and flexibility of aquatic ecosystems following the fluctuations of anthropogenic impact.