Urbanization and initial groundwater quality investigation in Malabe, Sri Lanka

Abstract

Malabe, an eastern suburb of the capitalcity of Colombo, is one of the most rapidly urbanized and industrialized areasin Sri Lanka. Groundwater is avaluable resource inMalabe and itis being polluted. Malabe is located in a wet climatic zone with alateritic aquifer thatnormally contains water with avery low pH thatcan cause quality problems. Our objective was to investigate and analyzethe Malabe groundwater quality to understand the characteristics of significant parameters and their correlation so that policy planning can be correctly done. Groundwater samples from 16 water wells were collected and evaluated for eightphysicochemical parameters,i.e.,pH, turbidity, electrical conductivity (EC), color, nitrate (NO3), nitrite (NO2), sulfate (SO4), and phosphate (PO4). Two biological parameters were also determined for four wells. The essence of this finding is that the groundwater is very acidic, has a very low EC, but high coliform counts. Multivariable statistics of the data were performed usingPearson’scorrelation and principal components analysis (PCA) using the Princom package intheR statistical package. The first four principal components (PCs) explained 79.8 % of the total observed variance inthe data. The most significant parametersfrom the first principalcomponent, PC1, were the positive correlationsof turbidity andPO4, and negative correlationsof EC andNO3. Asignificant positive loading of pH with a negative loading of SO4was illustrated in PC2. These findings were similar to the correlation results. We concludesthat the high acidity of the groundwater is primarily caused by industrial waste. The groundwater pollution of the Malabe area was not cause by inorganic fertilizer but by anthropogenic waste runoff. Our finding is crucial for groundwater quality management inthe study area.