Statistical evaluation of water quality parameters for two different seasons in Mahi estuary, west coast of India

Monthly and seasonal field sampling was conducted to characterize the variations in water column nutrients along four stations in the Mahi estuary, west coast of India from July 2008 to June 2009. Water samples from five stations were studied, from which Stations 1 and 2 are contaminated with effluents released by surrounding industrial complexes. The samples were analyzed for temperature and pH insitu, and salinity, alkalinity, dissolved oxygen, BOD, sulfate, nitrite, nitrate, total nitrogen, silicate-silicon, phosphate and calcium and magnesium, as per standard methods. The results showed an increased content of sulfate, nitrate, and total nitrogen in both Stations 1 and 2. The entire data has been factorized using principal component analysis to extract total variability and linear relationships for a set of different physico-chemical parameters of the Mahi estuarine system. The results revealed that all the physico-chemical processes depend on the seasonal fluctuations in freshwater input and sea-water intrusion. Cluster analysis was carried out for station-wise average values to understand the relationships between stations. Eigen values showed that PC1 was the most significant component, representing more than 90% of the variance in water quality parameters in the Mahi estuary for both monsoon and non-monsoon seasons. The results showed high deterioration in the physico-chemical quality of water during the non- -monsoon season compared to that in the monsoon season.