Characterization of bottom sediments and phosphorus fractions in hyper-eutrophic Krishnagiri reservoir located in an agricultural watershed in India

The hyper-eutrophicated Krishnagiri reservoir is situated in hot tropical and semiarid climate zone in South India. There are 16 villages in the command area, which are directly benefited by this reservoir, and water from the reservoir is used for irrigation, fish rearing, livestock rearing and recreation purposes. The reservoir is located in an agricultural watershed, and the rate of soil erosion in the catchment area is very high. Thus, the reservoir is severely affected by sedimentation, and half of its capacity was reduced. Previous studies in Krishnagiri reservoir clearly indicate the lack of information on the quality of sediments and dynamics of nutrient in the reservoir. Hence, the present study was conducted on bottom sediments, and it included the assessment of physicochemical characteristics and nutrients, such as composition, redox potential, moisture content, organic carbon, organic matter, total iron, manganese, calcium carbonate, different phosphorus fractions and total phosphorus. The increasing trend in organic matter and also the significant change from positive to high negative values of redox potential clearly indicate the inflow of high organic load which may result from the disposal of sewage and industrial waste water in the upstream catchment side. The high concentration of inorganic phosphorus fractions at the inflow point of the reservoir obviously implies that there was a significant input of nutrients into the reservoir. Hence, the study concludes that the rainfall, soil erosion and runoff are the major environmental factors for the input and accumulation of large quantities of nutrients in the bottom sediments of Krishnagiri reservoir during the study period. The present study clearly suggests for a careful investigation into sediment nutrients in Krishnagiri reservoir, and it is also necessary to assess the role of sediments in the phosphorus dynamics and its significant effect on eutrophication. This study demonstrates that the examination of physicochemical characteristics and nutrients in the bottom sediments is a helpful tool to identify the sources of nutrients to the reservoir. The baseline data provided in this paper will be helpful for the policy makers to frame better policies for the sustainable management of water quality in Krishnagiri reservoir.     

Longitudinal heterogeneity of sediment characteristics during southwest monsoon season in hyper-eutrophic Krishnagiri reservoir,India

Krishnagiri reservoir is a hyper-eutrophicated reservoir located in Krishnagiri district which is one of the drought-prone districts in Tamil Nadu, India. The reservoir water is being used for various purposes such as irrigation, drinking, fish rearing, livestock rearing, and recreation. Since there is no an evidence of investigation on bottom sediments in Krishnagiri reservoir, the present study was carried out during southwest monsoon season in 2008. This study examined the physical and chemical characteristics of the bottom sediments such as composition, redox potential, moisture content, organic carbon, organic matter, total phosphorus, and total iron at 15 locations in the reservoir. Phosphorus fractionation study was carried out to find out different fractions such as loosely adsorbed phosphorous, iron and aluminium-bound phosphorus, calcium-bound phosphorous, and organic phosphorous. Results indicated that there was spatial variation in the composition of sediments and low values of redox potential. The significant positive correlation exists between the organic carbon and organic phosphorus concentration. The lacustrine zone of the reservoir showed high accumulation of total phosphorus and total iron when compared to riverine and transition zones. This study concludes an allogenic origin of majority of inorganic phosphorus in the reservoir during the study period and this might have been derived from the catchment during the erosion process. The high concentration of surface sediment phosphorus clearly indicates a greater threat of eutrophication in Krishnagiri reservoir.     

Toxic effect of different types of titanium dioxide nanoparticles on Ceriodaphnia dubia in a freshwater system

Environmental Science and Pollution Research - In the current study, the effect of different types of titanium dioxide (TiO2) nanoparticles (NPs) (rutile, anatase, and mixture) was analyzed on...     

Contamination of microplastics,surface morphology and risk assessment in beaches along the Thoothukudi coast,Gulf of Mannar region

Environmental Science and Pollution Research - Microplastics accumulation on beaches raises a serious concern worldwide. Hence, the present study was conducted with the focus of investigating the...