The suitability of surface waters from small west-flowing rivers for drinking, irrigation, and aquatic life from a global biodiversity hotspot (Western Ghats, India).

The present study provides surface water types and water quality indices (WQI) for 70 large coastal rivers of the Western Ghats (WG). Irrespective of seasons and lithology, concentration of cations (Ca2+ > Na+ > Mg2+ > K+) and anions (HCO3- > Cl- >SO42- > NO3- > PO43-) follow a typical trend all along the coast. The WG rivers can broadly be classified as calcium-bicarbonate-chloride (Ca2+-HCO3--Cl-) type. Pearson correlation analysis of major ions demonstrates natural sources influence on the riverine water composition across the WG region. Gibbs plot suggests water composition of these rivers is the result of the interaction of rock and precipitation. It means that ionic contributions from precipitation and chemical weathering of rock-forming minerals largely determine surface water quality. This biodiversity hotspot is facing high population pressure and anthropogenic activities. Despite it, quantitatively, all the physical parameters and chemical constituents are within the permissible limits of the World Health Organization (WHO) and Bureau of Indian Standards (BIS), thus making it suitable for drinking and domestic purposes. About 86% of the surface water samples are found to be suitable for irrigation (KR < 1) in non-monsoon seasons. Rivers near to Goa coast are only found unsuitable (KR > 1) for irrigation exclusively during non-monsoon seasons. From the majority of the calculated indices, it may be inferred that the river waters draining from the WG region are suitable for irrigation. Overall, the calculated WQI for studied rivers showed excellent to good water quality for drinking, agriculture, and aquatic life in monsoon seasons, which are then ranked from good to marginal in non-monsoon seasons.

Export of particulate organic carbon by the mountainous tropical rivers of Western Ghats, India: Variations and controls.

Transport of organic carbon by small mountainous rivers is essential, but the poorly constrained component of the global carbon cycle. In the current research, we sampled and analyzed particulate organic carbon (POC) contents from 70 sizeable tropical coastal rivers, draining the Western Ghats (WG) of India. This study aimed to investigate the spatiotemporal variability in POC contents, to estimate flux and to identify environmental controls on POC sources and transport characteristics across the region. The averaged value of organic carbon (OC) in the particulate samples is 3.24%, and the mean POC concentration is 2.86 mg l-1. We classified the samples based on total suspended matter (TSM) classes for source appropriation. Litter/riparian (42.5%) pools are the largest source of organic matter, followed by autochthonous (36%) and soil (21.5%) for the WG region. However, locally autochthonous sources contribute exceptionally to POC pools, indicating a favorable environmental condition for the growth of algae and phytoplankton. Land-use & land-cover, climate, topography, and sediment erosion seems to be determining the local variability in sources to POC pools and fluxes. The POC export rates suggest that within the region, the POC yields of the Deccan Trap (DT) and the Western Dharwar Craton (WDC) blocks are about two times higher than that of the Southern Granulite Terrain (SGT) region. With POC yield of 7.0 g m-2 yr-1, this region exports 0.79 Tg C (~ 0.5% of the global POC) to the Arabian Sea annually. The POC flux of the WG region (covering 0.25% of Asia's land area) is approximately 1.0% of Asia's riverine POC flux to the ocean.

Synthesis, stability, and antimicrobial studies of electronically tuned silver acetate N-heterocyclic carbenes.

A series of methylated imidazolium salts with varying substituents on the 4 and 5 positions of the imidazole ring were synthesized. These salts were reacted with silver acetate to afford their corresponding silver N-heterocyclic carbene (NHC) complexes. These complexes were then evaluated for their stability in water as well as for their antimicrobial efficacy against a variety of bacterial strains associated with cystic fibrosis and chronic lung infections.

Synthesis and characterization of a trigonal bipyramidal supramolecular cage based upon rhodium and platinum metal centers.

The reaction of 4-ethynyl-pyridine with tert-butyl lithium followed by its addition to (Me3tacn)RhCl3 affords the facial octahedral complex (Me3tacn)Rh(CCPy)3, condensation of which with the square planar complex cis-(DCPE)Pt(NO3)2 results in a self-assembled trigonal bipyramidal cage with Rh(III) and Pt(II) atoms occupying the vertices.

Vitamin C metabolomic mapping in experimental diabetes with 6-deoxy-6-fluoro-ascorbic acid and high resolution 19F-nuclear magnetic resonance spectroscopy.

Metabolomic mapping is an emerging discipline geared at providing information on a large number of metabolites as a complement to genomics and proteomics. Here we have probed ascorbic acid homeostasis and degradation in diabetes using 6-deoxy-6-fluoro ascorbic acid (F-ASA) and 750 MHz (19)F-nuclear magnetic resonance (NMR) spectroscopy with proton decoupling In vitro, Cu(2+)-mediated degradation of F-ASA revealed the formation of 4 major stable degradation products at 24 hours. However, when normal or diabetics rats were injected with F-ASA intraperitoneally (IP) for 4 days, up to 20 fluorine-labeled compounds were observed in the urine. Their composition resembled, in part, metal catalyzed degradation of F-ASA and was not explained by spontaneous degradation in the urine. Diabetes led to a dramatic increase in urinary F-ASA loss and a relative decrease in most other urinary F-compounds. Diabetes tilted F-ASA homeostasis toward oxidation in liver (P <.01), kidney (P <.01), spleen (P <.01), and plasma (P <.01), but tended to decrease oxidation in brain, adrenal glands, and heart. Surprisingly, however, besides the major oxidation product fluoro-dehydroascorbic acid (F-DHA), no F-ASA advanced catabolites were detected in tissues at 5 micromol/L sensitivity. These findings not only confirm the key role of the kidney in diabetes-mediated loss of ascorbic acid, but demonstrate that only selected tissues are prone to increased oxidation in diabetes. While the structure of most degradation products needs to be established, the method illustrates the power of high resolution (19)F-NMR spectroscopy for the mapping of complex metabolomic pathways in disease states.

Vitamin C metabolomic mapping in the lens with 6-deoxy-6-fluoro-ascorbic acid and high-resolution 19F-NMR spectroscopy.

PURPOSE: Metabolomics, or metabolic profiling, is an emerging discipline geared to providing information on a large number of metabolites, as a complement to genomics and proteomics. In the current study, a fluorine-labeled derivative of ascorbic acid (F-ASA), a major antioxidant- and UV-trapping molecule in the aqueous humor and the lens, was used to investigate the extent to which the lens accumulates potentially toxic degradation products of vitamin C. METHODS: Human lens epithelial cells (HLE-B3) and rat lenses were exposed to hyperglycemic or oxidative stress in vitro or in vivo and probed for accumulation of F-ASA, fluoro-dehydroascorbate (F-DHA), fluoro-2,3-diketogulonate (F-DKG), and their degradation products in protein-free extracts, by proton-decoupled 750-MHz (19)F-nuclear magnetic resonance (NMR) spectroscopy. RESULTS: F-ASA and F-DHA were taken up into HLE B-3 cells by an Na(+)-dependent transporter. Their uptake was unexpectedly only slightly affected by hyperglycemia in vitro, unless glutathione was severely depleted. Glycemic stress catalyzed oxidation of F-ASA into a single novel F-compound at -212.4 ppm, whereas F-DHA and F-DKG were the major degradation products observed after GSH depletion. In contrast, F-ASA uptake was markedly suppressed in diabetic cataractous rat lenses, which accumulated both the F-DHA and the -212.4-ppm compound. In an unexpected finding, the latter formed only from F-ASA and not F-DHA or F-DKG, suggesting a novel pathway of in vivo F-ASA degradation. Both the cells and the intact rat and human lenses were permeable to several advanced F-ASA and F-DHA degradation products, except F-DKG. The unknown compound at -212.4 ppm was the only F-ASA degradation product that spontaneously formed in rabbit aqueous humor upon incubation with F-ASA. CONCLUSIONS: These studies suggest the existence of a novel ascorbic-acid-degradation pathway in the lens and aqueous humor that is influenced by the nature of the oxidant stress. Under similar culture conditions, intact lenses are more prone to hyperglycemia-mediated oxidant stress than are lens epithelial cells, but both are permeable to various F-ASA degradation products, the structure and biological roles of which remain to be established.