Occurrence of toxigenic cyanobacterial blooms in freshwaters of Sri Lanka.

A previous pioneering study of freshwater bodies in Sri Lanka revealed the presence of toxic cyanobacteria in three out of four water bodies tested. It was therefore important to perform a more detailed investigation into the presence of cyanobacteria and their toxins throughout Sri Lanka. The country has a long history of well-planned water management with the agricultural economy and drinking water supply still dependent on thousands of man-made tanks. Seventeen reservoirs from different user categories and different climatic zones were selected to study variations in phytoplankton communities with relation to major nutrients, with particular emphasis on cyanobacteria. The study was carried out during a two-year period and heavy growths or blooms of cyanobacteria observed during the study period were tested for microcystins. The results clearly categorised the 17 reservoirs into four groups parallel to the classification based on the user categories of water bodies. Biomass of total phytoplankton, the abundance of cyanobacteria, the dominance of Microcystis spp. and concentration of nitrate (N) and total phosphorous (P) were the lowest in drinking water bodies and the highest in aesthetic water bodies. Irrigation water bodies showed the second lowest values for phytoplankton biomass, and concentration of N and P, while hydropower reservoirs showed the second highest values for the same parameters. The fraction of cyanobacteria in irrigation waters was higher than that in hydropower reservoirs, but surprisingly the dominance of Microcystis spp. was reversed. Possible reasons for these variations are discussed. More than half of the bloom material tested contained microcystins up to 81 μg l−1. Our findings indicate the potential for high-risk situations due to toxigenic cyanobacterial blooms in susceptible freshwaters of Sri Lanka

Enhancing photocatalytic degradation of the cyanotoxin microcystin-LR with the addition of sulfate-radical generating oxidants.

This study investigated the coupling of sulfate radical generating oxidants, (persulfate, PS and peroxymonosulfate, PMS) with TiO2 photocatalysis for the degradation of microcystin-LR (MC-LR). Treatment efficiency was evaluated by estimating the electrical energy per order (EEO). Oxidant addition at 10 mg/L reduced the energy requirements of the treatment by 60% and 12% for PMS and PS, respectively compared with conventional photocatalysis. Quenching studies indicated that both sulfate and hydroxyl radicals contributed towards the degradation of MC-LR for both oxidants, while Electron Paramagnetic Resonance (EPR) studies confirmed that the oxidants prolonged that lifetime of both radicals (concentration maxima shifted from 10 to 20min), allowing for bulk diffusion and enhancing cyanotoxin removal. Structural identification of transformation products (TPs) formed during all treatments, indicated that early stage degradation of MC-LR occurred mainly on the aromatic ring and conjugated carbon double bonds of the ADDA amino acid. In addition, simultaneous hydroxyl substitution of the aromatic ring and the conjugated double carbon bonds of ADDA (m/z= 1027.5) are reported for the first time. Oxidant addition also increased the rates of formation/degradation of TPs and affected the overall toxicity of the treated samples. The detoxification and degradation order of the treatments was UVA/TiO2/PMS > UVA/TiO2/PS>> UVA/TiO2

Energy efficient operation of photocatalytic reactors based on UV LEDs for pollution remediation in water.

Photocatalytic technology using TiO2 is one of the emerging approaches for water treatment, especially as a final step to remove complex organics such as pesticides, hormones or humic acids. Titanium dioxide (TiO2) is a semiconductor material with strong UV absorption band and exhibits strong photocatalytic activity. The photocatalytic activity of TiO2 powders have been extensively studied, using UV light sources. However, the incident photons that initiate the process of photocatalytic oxidation using titanium dioxide are not efficiently used, this is responsible for the low photonic efficiency that characterise oxidation of aqueous pollutants hence its limitation in industrial applications. Periodic illumination has been investigated as a means of increasing the photonic efficiency in a photoreactor with acid orange as a model pollutant. Results indicate more than four-fold increase in photonic efficiency through periodic illumination compared to continuous illumination. This approach can improve the energy efficiency of the photocatalytic water treatment systems

Rapid bioassay-guided isolation of antibacterial clerodane type diterpenoid from Dodonaea viscosa (L.) Jaeq

Plant extracts are complex matrices and, although crude extracts are widely in use, purified compounds are pivotal in drug discovery. This study describes the application of automated preparative-HPLC combined with a rapid off-line bacterial bioassay, using reduction of a tetrazolium salt as an indicator of bacterial metabolism. This approach enabled the identification of fractions from Dodonaea viscosa that were active against Staphylococcus aureus and Escherichia coli, which, ultimately, resulted in the identification OPEN ACCESS of a clerodane type diterpenoid, 6\u3b2-hydroxy-15,16-epoxy-5\u3b2, 8\u3b2, 9\u3b2, 10\u3b1-cleroda-3, 13(16), 14-trien-18-oic acid, showing bacteriostatic activity (minimum inhibitory concentration (MIC) = 64\u2013128 \u3bcg/mL) against test bacteria. To the best of our knowledge, this is the first report on antibacterial activity of this metabolite from D. viscosa

Weather, disease, and wheat breeding effects on Kansas wheat varietal yields, 1985 to 2011.

Wheat (Triticum aestivum L.) yields in Kansas have increased due to wheat breeding and improved agronomic practices, but are subject to climate and disease challenges. The objective of this research is to quantify the impact of weather, disease, and genetic improvement on wheat yields of varieties grown in 11 locations in Kansas from 1985 to 2011. Wheat variety yield data from Kansas performance tests were matched with comprehensive location-specific disease and weather data, including seasonal precipitation, monthly air temperature, air temperature and solar radiation around anthesis, and vapor pressure deficit (VPD). The results show that wheat breeding programs increased yield by 34 kg ha⁻¹ yr⁻¹. From 1985 through 2011, wheat breeding increased average wheat yields by 917 kg ha⁻¹, or 27% of total yield. Weather was found to have a large impact on wheat yields. Simulations demonstrated that a 1°C increase in projected mean temperature was associated with a decrease in wheat yields of 715 kg ha⁻¹, or 21%. Weather, diseases, and genetics all had significant impacts on wheat yields in 11 locations in Kansas during 1985 to 2011

Emollients for prevention of atopic dermatitis; 5‐year findings from the BEEP randomised trial

Background The effectiveness of emollients for preventing atopic dermatitis/eczema is controversial. The Barrier Enhancement for Eczema Prevention trial evaluated the effects of daily emollients during the first year of life on atopic dermatitis and atopic conditions to age 5 years. Methods 1394 term infants with a family history of atopic disease were randomized (1:1) to daily emollient plus standard skin-care advice (693 emollient group) or standard skin-care advice alone (701 controls). Long-term follow-up at ages 3, 4 and 5 years was via parental questionnaires. Main outcomes were parental report of a clinical diagnosis of atopic dermatitis and food allergy. Results Parents reported more frequent moisturizer application in the emollient group through to 5 years. A clinical diagnosis of atopic dermatitis between 12 and 60 months was reported for 188/608 (31%) in the emollient group and 178/631 (28%) in the control group (adjusted relative risk 1.10, 95% confidence interval 0.93 to 1.30). Although more parents in the emollient group reported food reactions in the previous year at 3 and 4 years, cumulative incidence of doctor-diagnosed food allergy by 5 years was similar between groups (92/609 [15%] emollients and 87/632 [14%] controls, adjusted relative risk 1.11, 95% confidence interval 0.84 to 1.45). Findings were similar for cumulative incidence of asthma and hay fever. Conclusions Daily emollient application during the first year of life does not prevent atopic dermatitis, food allergy, asthma or hay fever