Chronic kidney disease in two coastal districts of Andhra Pradesh, India: role of drinking water

Chronic kidney disease (CKD) has been reported in a few coastal regions of Srikakulam district and Chimakurthy mandal (~30–40 km away from the coast) in the Prakasham district of Andhra Pradesh, India. Some medical experts and the local population have apprehensions that the drinking water is the sole reason for this disease in these areas. As the source of drinking water for these two regions is only groundwater, major ions and trace elements were measured on waters from different sources to identify the causative element(s), if any. Comparison of hydrochemical data of both the areas indicates that groundwater in Srikakulam coastal region is less mineralized than that of the Prakasham region, which may be due to geological, hydrological and climatic reasons. However, the concentrations of various inorganic chemicals are within the permissible limits of drinking water. Hence, for the inorganic chemicals to cause ill health, including CKD, is unlikely or is ruled out in the study areas.     

Photodegradation of fungicide triadimefon and pesticide pirimicarb in aqueous TIO2 suspension

Two agrochemicals composed of nitrogen‐containing heterocyclic ring, triadimefon and pirimicarb, were degraded photocatalytically. The disappearance and TOC elimination rates of triadimefon were close to those of pirimicarb, whereas the photolysis of triadimefon was 4 times slower than that of pirimicarb. For triadimefon its aromatic moiety degraded quickly and Cl^‐ was released immediately, while triazole moiety degraded slowly. The formation rates of NH⁺ ₄ and NO₃ ^‐ by the degradation of triazole moiety were influenced by the rest of the molecule. The difference between disappearance and TOC elimination rates of both triadimefon and pirimicarb were far larger than those of aromatic compounds.     

Performance and validation of a coupled parallel ADCIRC–SWAN model for THANE cyclone in the Bay of Bengal

An accurate prediction of near-shore sea-state is imperative during extreme events such as cyclones required in an operational centre. The mutual interaction between physical processes such as tides, waves and currents determine the physical environment for any coastal region, and hence the need of a parallelized coupled wave and hydrodynamic model. The present study is an application of various state-of-art models such as WRF, WAM, SWAN and ADCIRC used to couple and simulate a severe cyclonic storm Thane that developed in the Bay of Bengal during December 2011. The coupled model (ADCIRC–SWAN) was run in a parallel mode on a flexible unstructured mesh. Thane had its landfall on 30 December, 2011 between Cuddalore and Pondicherry where in-situ observations were available to validate model performance. Comprehensive experiment on the impact of meteorological forcing parameters with two forecasted tracks derived from WRF model, and JTWC best track on the overall performance of coupled model was assessed. Further an extensive validation experiment was performed for significant wave heights and surface currents during Thane event. The significant wave heights measured along satellite tracks by three satellites viz; ENVISAT, JASON-1 and JASON-2, as well in-situ near-shore buoy observation off Pondicherry was used for comparison with model results. In addition, qualitative validation was performed for model computed currents with HF Radar Observation off Cuddalore during Thane event. The importance of WRF atmospheric model during cyclones and its robustness in the coupled model performance is highlighted. This study signifies the importance of coupled parallel ADCIRC–SWAN model for operational needs during extreme events in the North Indian Ocean.     

Alkali Treated 3D Chitosan Scaffolds with Enhanced Strength and Stability

Journal of Polymers and the Environment - 3D chitosan scaffolds treated with alkali showed enhanced mechanical properties and stability in aqueous conditions. Chitosan is a preferred polymer for...     

Biodegradable Chitosan Hydrogels for In Vitro Drug Release Studies of 5-Flurouracil an Anticancer Drug

Novel semi-interpenetrating network (semi-IPN) hydrogels based on biodegradable chitosan and poly(N-isopropylacrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid) were prepared by free radical addition polymerization. Fourier transform infrared spectra and scanning electron microscopy were used to characterize the semi-IPN hydrogels and the results showed that chitosan and poly(N-isopropylacrylamide-co-2-acrylamide-2-methyl-1-propanesulfonic acid) semi-IPN hydrogels were coupled by the interaction of the functional groups present in NIPAAm, CS and AMPS units. The PNIPAAm and P(NIPAAm-AMPS)/CS hydrogels have lower critical solution temperature and the same was confirmed with the help of differential scanning calorimetry as well as with the temperature dependent swelling curves. The model anti cancer drug, 5-fluorouracil (5-FU) was loaded into the semi-IPN hydrogels, at ambient temperature. The 5-FU loading capacity and release behaviour were investigated with these hydrogels acting as carriers for controlled release. The released 5-FU concentration was calculated with the help of UV spectrophotometer at 266.5?nm.     

Ammonia volatilization from marsh-pond-marsh constructed wetlands treating swine wastewater

Ammonia (NH3) volatilization is an undesirable mechanism for the removal of nitrogen (N) from wastewater treatment wetlands. To minimize the potential for NH3 volatilization, it is important to determine how wetland design affects NH3 volatilization. The objective of this research was to determine how the presence of a pond section affects NH3 volatilization from constructed wetlands treating wastewater from a confined swine operation. Wastewater was added at different N loads to six constructed wetlands of the marsh-pond-marsh design that were located in Greensboro, North Carolina, USA. A large enclosure was used to measure NH3 volatilization from the marsh and pond sections of each wetland in July and August of 2001. Ammonia volatilized from marsh and pond sections at rates ranging from 5 to 102 mg NH3-N m(-2) h(-1). Pond sections exhibited a significantly greater increase in the rate of NH3 volatilization (p < 0.0001) than did either marsh section as N load increased. At N loads greater than 15 kg ha(-1) d(-1), NH3 volatilization accounted for 23 to 36% of the N load. Furthermore, NH3 volatilization was the dominant (54-79%) N removal mechanism at N loads greater than 15 kg ha(-1) d(-1). Without the pond sections, NH3 volatilization would have been a minor contributor (less than 12%) to the N balance of these wetlands. To minimize NH3 volatilization, continuous marsh systems should be preferred over marsh-pond-marsh systems for the treatment of wastewater from confined animal operations.     

Response of biogeochemical indicators to a drawdown and subsequent reflood

Temporal oscillations in hydrology are a common occurrence in wetlands and can result in alternating flooded and drained conditions in the surface soil. These oscillations in water levels can stimulate microbial activities and result in the mobilization and redistribution of significant amounts of carbon (C), nitrogen (N), and phosphorus (P). The goal of this study was to experimentally simulate a drawdown and reflood of marsh soil from a nutrient-enriched site and a reference site of a wetland (Blue Cypress Marsh Conservation Area, Florida). The goal was to better understand the changes in biogeochemistry and microbial activities present in these soils as a result of hydrological fluctuations. Measurements of dissolved reactive phosphorus (DRP), ammonia, and nitrate in the floodwater indicated significantly higher (alpha = 0.05) NH(4)(+) and DRP fluxes from the nutrient-enriched site; floodwaters in the cores from both sites contained significant NO(3)(-) concentrations (9.6 mg N L(-1)), which was rapidly consumed over the core incubation period (30 d). Water level drawdown and reflooding initially stimulated the soil microbial biomass, methanogenic rates, and extracellular enzyme activities (acid phosphatase and beta-glucosidase). The anaerobic microbial metabolic activities (CO(2)) where initially significantly (alpha = 0.05) enhanced by the reflood, resulting in roughly equivalent rates as the aerobic respiratory activities (CO(2)), presumably as a function of the high water column NO(3)(-) levels. This study illustrates that the reflood event in the hydrological cycles in a wetland can significantly stimulate the activities of hydrolytic enzymes and microbiological communities in these soils.     

Spatio-temporal patterns of soil phosphorus enrichment in Everglades water conservation area 2A

The Florida Everglades have undergone significant ecological change resulting from anthropogenic manipulation of historical regimes of hydrology, nutrient loading, and fire. Water Conservation Area 2A (WCA-2A) in the northern Everglades has been a focal point for the study of ecological effects of nutrient loading, especially phosphorus (P), from the nearby Everglades Agricultural Area (EAA). The overall objective of our study was to evaluate recent (1990 to 1998) changes in the spatial extent and patterns of soil P enrichment in Everglades WCA-2A. Surface soil was sampled to a depth of 10 cm at 62 sites within WCA-2A during 1998 for analysis of total phosphorus (TP) content. Geostatistical methods were used to create an interpolated grid of soil TP values across WCA-2A. Comparison of the results of this study with a similar study performed in 1990 showed that the extent of soil P enrichment in surface soil and sediments increased between 1990 and 1998, as evidenced by increased coverage of highly P-enriched soil near the primary surface inflows and a general increase in the concentration of soil TP in the interior regions of WCA-2A. Approximately 73% (31 777 ha) of the total land area of WCA-2A was considered P-enriched (soil total P > 500 mg kg(-1)) in 1998, compared with 48% of the land area (20,829 ha) in 1990, an average increase of 1,327 ha yr(-1). Study results indicate that the soil P enrichment "front" has advanced further into the relatively unimpacted interior of WCA-2A during the past several years.     

Phosphorus flux from wetland soils affected by long-term nutrient loading

Wetland soils play a key role in the cycling of nutrients within an ecosystem. Since soils are potentially a source or a sink for inorganic nutrients, it is important to quantify their influence on overlying water quality in order to understand their importance in overall ecosystem nutrient budgets. Laboratory and field studies were performed in the northern Everglades (WCA-2A) to determine the magnitude of phosphorus (P) flux between the soil and the overlying water column, under various redox conditions. The P flux was estimated using three techniques: intact soil cores, in situ benthic chambers, and porewater equilibrators. There was reasonable agreement between the P flux estimated using intact soil cores and benthic chambers; however, P flux estimates using the porewater equilibrators were considerably lower than the other two techniques. Models of solute flux, based solely on soil physico-chemical characteristics, may substantially underestimate soil-water nutrient exchange processes. Phosphorus flux measured with the intact soil cores varied from 6.5 mg m(-2) d(-1) near nutrient inflow areas to undetectable flux 4 km away from the inflow. Oxygen consumption varied from 4 mg m(-2) d(-1) near the inflow to a constant 1 to 2 mg m(-2) d(-1) at a distance of 4 km from the inflow. Rate of consumption of NO3- -N and SO4(2-) showed no significant trend with respect to distance from inflow. Nitrate N and SO4 consumption rates averaged 120 and 130 mg m(-1) d(-1), respectively. Consumption of O2 was correlated with P flux, whereas NO3- -N and SO4(2-) consumption were not.