Seven representative sampling stations were selected from Indus Delta comprising of (1) Keti Bander, (2) Darya Peer, (3) Kharo Chanr, (4) Jati, (5) Shah Bander, (6) Nariri Dhand and (7) Left Bank Outfall Drain (LBOD) near Rupa Mari. The sampling scheme was repeated seven times during 2014-2015 for 1 year. The samples were analysed for temperature, conductivity, pH, hardness, chloride, alkalinity, dissolved oxygen, biological oxygen demand, chemical oxygen demand, sulphate, orthophosphate-P, nitrite-N, nitrate-N, Na, K, Fe, Ni, Cr, Co, Cd, Zn, Cu, Pb and As. The analysis was carried out using standard analytical procedures. A number of parameters crossed the WHO permissible limits and water quality guidelines for aquatic life and indicated pollution within coastal region. Coefficient of correlation (r) among physicochemical parameters and metal ions were examined and a number of parameters did not correlate positively and did not indicate natural origin and may indicate their presence due to human activity. The samples were examined for cluster analysis, and principal component analysis. The samples also indicated the presence of Presumptive Coliform, Faecal coliform and E. coli.

Background: Adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U) are building blocks and major constituents of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The metabolic pathway of DNA and RNA is strongly related to A, G, C, T, and U.

BACKGROUND: The current study suggests an experimental and modeling approach for the adsorptive removal of lead(II) ions from contaminated water sample. The Schiff base reagent, bis(salicylaldehyde)ethylenediimine (Salen) functionalized graphene oxide (GO) was applied as adsorbent. Salen functionalized GO was prepared and characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, zeta potential and dynamic light scattering (DLS) techniques. The batch experiment represented maximum removal efficiency of 99% at pH 6.5, adsorbent dose of 100 mg L −1 and 5 min contact time.RESULTS: The residual concentration of lead(II) after removal was measured using flame atomic absorption spectrometry. DLS results suggested slightly smaller particle size of Salen modified GO than pristine GO. The optimized model calculated with Gaussian 09 W software showed maximum total energy (1.3959 eV) and dipole moment (6.8646 D) for model of lead interaction with Salen-GO. The Langmuir adsorption isotherm model was most fitted and the kinetic data indicated that the lead(II) adsorption on Salen-GO followed second-order model. The maximum adsorption capacity calculated was 68 mg g −1 .CONCLUSION: The adsorbent was applied to remove lead(II) ions in real contaminated water samples of the battery manufacturing industry with average removal of 95% with relative standard deviation 1.23% (n = 3). The adsorbent was reusable with desorption of lead(II) from adsorbent and was 95% with 0.2 mol L -1 nitric acid.

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