Banaras Hindu University

About: Banaras Hindu University is a education organization based out in Varanasi, Uttar Pradesh, India. It is known for research contribution in the topics: Population & Catalysis. The organization has 11858 authors who have published 23917 publications receiving 464677 citations. The organization is also known as: Kashi Hindu Vishvavidyalay & Benares Hindu University.

Assessment of heavy metal pollution in water and surface sediment and evaluation of ecological risks associated with sediment contamination in the Ganga River: a basin-scale study

Abstract: We investigated eight heavy metals (Cr, Cd, Cu, Ni, Pb, Zn, Mn, and Fe) in water and bed sediment at 9 study sites along with 2320 km stretch of the Ganga River. Principal component analysis (PCA) and indices such as geo-accumulation index (Igeo), contamination factor (CF), enrichment factor (EF), pollution indices, and sediment quality guidelines were used to assess source apportionment and magnitude of contamination. Concentrations of Cr, Cd, Pb, Ni, Cu, and Fe in water have exceeded their respective standards in the middle and lower reaches of the river. Sediment Cr and Ni have reached probable effective concentration (PEC) at Kannauj, imposing likely threats to sediment dwellers. Highest Igeo values were recorded for Cr, Cd, and Pb at Kannauj, Rajghat, and Howrah. We further tested ecological risks (Er) and potential ecological risks (PERI) to assess individual and cumulative effects and found the Kannauj, Rajghat, and Howrah sites under the high-risk category. The modified pollution index (MPI) and the modified degree of contamination (mCd) also revealed the middle and lower river reaches under moderately to the heavily polluted category. Our study provides the first detailed watershed-scale database on heavy metal concentration in water and bed sediment, the magnitude of contamination, and likely ecological risks to aquatic organisms in the Ganga River. Given that the Ganga water is used for drinking and irrigation and the river harbors a diversity of habitats for fisheries, the study merits attention from a human health perspective as well.

Structural and up-conversion properties of Er3+ and Yb3+ co-doped Y2Ti2O7 phosphors.

Abstract: Y2Ti2O7 (YTO) and Er3+/Yb3+ co-doped Y2Ti2O7 (EYYTO) phosphors have been prepared by solid-state reaction method. Structures of YTO and EYYTO phosphors are identified as face centered cubic pyrochlores. Up-conversion emission spectra of EYYTO under 976 nm excitation is studied, which revealed three prominent emission lines at ∼524, 548 and 661 nm originating from 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 electronic transitions of Er3+ ion, respectively in green and red regions. The power dependence study suggests that these bands arise due to two photon absorption. The monodispersed laser ablated colloidal solution of EYYTO shows strong red and green emissions on excitation with 976 nm laser. The variation of luminescence intensity at different laser excitation powers is observed and thus a color can be tuned. The photoluminescence lifetime of green band at 548 nm (4S3/2 level) has been found to be ∼446 μs.