Evaluation of Eutrophication and Decomposition of Organic Phosphorus of River Water and Summer Season Ground Water Quality of Dinajpur

Abstract

Groundwater (70 samples from tubewells and shallow tubewells) and surface water (18 samples from 3 rivers in 18 sampling sites) collected from the Dinajpur Sadar Upazilla, Dinajpur, Bangladesh in dry season of the year June, 2012 to Feb, 2013 and analyzed for its quality and suitability for different purposes. Analyses included pH, EC, temperature, Dissolved Oxygen (DO), Chemical Oxygen demand (COD), alkalinity, cations (Ca**, Mg”*, Na’, K*, Zn**, Cu’*, Mn”* and Fe**), anions (CO;”, HCO;, NH3, NO2, NOs, SO,”, total nitrogen, total phosphorus and Cl) and TDS. Several variables such as SAR, SSP, RSC and hardness were also computed. Water samples contained Ca’*, Mg”* and Na‘ as the dominant cations and HCO; and CI were the dominant anions. Most of the samples were suitable for different purposes. Water eutrophication has become a worldwide environmental problem in recent years, and understanding the mechanisms of water eutrophication will help for prevention and remediation of water eutrophication. In this study, recent advances in current status and major mechanisms of water eutrophication, assessment and evaluation criteria, and the influencing factors were reviewed. The assessment of water eutrophication has been advanced from simple individual parameters like total phosphorus, total nitrogen, etc., to comprehensive indexes like total nutrient status index. The major influencing factors on water eutrophication include nutrient enrichment, hydrodynamics, environmental factors such as temperature, salinity, carbon dioxide, element balance etc. and microbial and biodiversity. The occurrence of water eutrophication is actually a complex function of all the possible influencing factors. The mechanisms of algal blooming are not fully understood and need to be further investigated. The decomposition of organic phosphorus in natural water is determined by a large number of physical driven transformation processes. Many of these processes are known in principle but often the decomposition rate into the aquatic environment in a number of different forms, and have been described as being can hardly be measured with a sufficient spatial and temporal resolution. Phosphorus is introduced present in the dissolved phase as a small fraction of the total and in the particulate phase as a large fraction of the total. Each fraction is made up of a large number of different components, most of which may change between their dissolved or particulate state. The decomposition rate coefficients of POP and DOP are 0.038 day” and 0.251 day respectively. These decomposition coefficients might be suitable for modeling the water quality.