Impact of pollutants on water quality and distribution of macrophytes in Tuikual river, Aizawl, Mizoram

The current investigation was conducted in Aizawl, Mizoram, from upstream to downstream of the Tuikual river. It is a major tributary of the Tlawng river, which supplies water to Aizawl, Lunglei, and a number of neighbouring settlements. The primary goal of the research is to determine the influence of contaminants on the water quality and distribution of aquatic macrophytes in the Tuikual river. Site 1 is located near the river's source, and the river also obtains discharge from Aizawl Civil Hospital, the state's major hospital. Site 2 is in downstream of the river following the confluence of streams at Site 1 polluted by discharge of domestic trash from cities as well as discharges from Ebenezer Hospital. Site 3 is in downstream of Site 2 and includes overflow from sandstone rocks. Site 4 is downstream from Site 3 in the area where the river enters the Tlawng river The DO, turbidity, and phosphate-P levels were not within the limitations established by several organizations. Twentysix macrophytes were recorded from 15 families. The aquatic plants with the highest importance value index (IVI) at Sites 1, 2, 3, and 4 were Commelina benghalensis (57.0), Commelina benghalensis (65.9), Echinochloa stagnina (50.1), and Equisetum hyemale (45.7), respectively. The Shannon-Weiner diversity index (H'), species evenness (J'), and species richness (D_mg) were highest (H'=2.548; J'=0.9; D_mg =2.46) at the least polluted site (Site 4), whereas Simpson dominance (D) was highest (D=0.186) at the most polluted site (Site 2). The polluted areas (Sites 1 and 2) had the highest similarity index (88%). The findings indicate that the values of macrophyte-based indices reflect water quality at different sample sites and may be used to measure river ecological health.