Evaluating Water Quality in Northern and Eastern Coastal Zones of Sri Lanka: A Baseline Study for Environmental Monitoring and Conservation

Abstract

The coastal area of Sri Lanka that accounts for nearly 1650 km stretch functions as a major source of livelihood, habitat, tourism, aquaculture, and trade. Although the coastal area offers a wide range of benefits to almost 55% of Sri Lanka’s Population, the coastal areas face severe threats due to factors such as aquatic pollution, coastal erosion, ecosystem degradation, urbanization, and sand mining. Therefore, to sustain the ecosystem stability and conserve of the coastal environment, it is crucial to conduct environmental monitoring of the coastal environment. However, a significant number of water quality assessments have been already carried out so far, only targetting the Western and Southern coastal zones of Sri Lanka. Therefore, this study intends to assess the marine water quality in selected locations (Total=26 Locations) in Northern (Mannar, Pooneryn, Kilinochchi, Jaffna, Mullaithivu) and Eastern (Trincomalee) coastal zones. Water samples were collected from these locations and both in-situ and laboratory analyses were carried out for Physico-chemical parameters (pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Nutrients- Nitrates, Nitrites, and Ammonia, Turbidity, Total Dissolved Solids (TDS), Total Suspended Solids (TSS) following APHA standards. Based on the data collected, water quality was assessed using a Water Quality Index and R- statistical Programming software. The results show that statistically significant differences in TDS (P=0.004), COD (P= 0.036), and Nitrites (P=0.009) levels were found between all the locations during ANOVA, nevertheless no significant variation in COD during HSD test. The heat map analysis of water quality index model suggested that some of the locations in Mannar, Pooneryn, and Jaffna have indicated very poor water quality, while Trincomalee and Mullaithivu exhibited moderate to good water quality for selected locations. Overall, these results deliver us a clear picture to understand the current status of each of this selected location based on the water quality parameters. Therefore, it can be concluded that water quality monitoring and application of the water quality index approach should be carried out in each costal district to develop a database that can be inevitably referred to as baseline information during coastal ecosystem management, conservation efforts and even during any emergency case mitigation such as oil spills and ship fire incidents.