Interference from HONO in the measurement of ambient air NO2 via photolytic conversion and quantification of NO

The reference method to quantify mixing ratios of the criteria air pollutant nitrogen dioxide (NO₂) is NO-O₃ chemiluminescence (CL), in which mixing ratios of nitric oxide (NO) are measured by sampling ambient air directly, and mixing ratios of NO_x (= sum of NO and NO₂) are measured by converting NO₂ to NO using, for example, heated molybdenum catalyst or, more selectively, photolytic conversion (P-CL). In this work, the nitrous acid (HONO) interference in the measurement of NO₂ by P-CL was investigated. Results with two photolytic NO₂ converters are presented. The first used radiation centered at 395 nm, a wavelength region commonly utilized in P-CL. The second used light at 415 nm, where the overlap with the HONO absorption spectrum and hence its photolysis rate are less. Mixing ratios of NO₂, NO_x and HONO entering and exiting the converters were quantified by Thermal Dissociation Cavity Ring-down Spectroscopy (TD-CRDS). Both converters exhibited high NO₂ conversion efficiency (CF_NO2; > 90%) and partial conversion of HONO. Plots of CF against flow rate were consistent with photolysis frequencies of 4.2 s^-1 and 2.9 s^-1 for NO₂ and 0.25 s^-1 and 0.10 s^?1 for HONO at 395 nm and 415 nm, respectively. CF_HONO was larger than predicted from the overlap of the emission and HONO absorption spectra. The results imply that measurements of NO₂ by P-CL marginally but systematically overestimate true NO₂ concentrations, and that this interference should be considered in environments with high HONO:NO₂ ratios such as the marine boundary layer or in biomass burning plumes.     

An empirically tested overlap between indigenous and scientific knowledge of a changing climate in Bolivian Amazonia

Regional Environmental Change - Existing climate data for Bolivian Amazonia rely on observations from a few sparse weather stations, interpolated on coarse-resolution grids. At the same time, the...     

Biogas from poultry waste—production and energy potential

The objective of this study was to evaluate the effect of heat treatment on poultry litter with different levels of reutilisation for potential generation of biogas in experimental biodigesters. Chicken litter used was obtained from two small-scale poultry houses where 14 birds m^?2 were housed for a period of 42 days per cycle. Litter from aviary 1 received no heat treatment while each batch of litter produced from aviary 2 underwent a fermentation process. For each batch taken, two biodigesters were set for each aviary, with hydraulic retention time of 35 days. The efficiency of the biodigestion process was evaluated by biogas production in relation to total solids (TS) added, as well as the potential for power generation. Quantified volumes ranged from 8.9 to 41.1 L of biogas for aviary 1, and 6.7 to 33.9 L of biogas for aviary 2, with the sixth bed reused from both aviaries registering the largest biogas potential. Average potential biogas in m³ kg^?1 of TS added were 0.022 to 0.034 for aviary 1 and 0.015 to 0.022 for aviary 2. Energy values ??of biogas produced were calculated based on calorific value and ranged from 0.06 to 0.33 kWh for chicken litter without fermentation and from 0.05 to 0.27 kWh for chicken litter with fermentation. It was concluded that the re-use of poultry litter resulted in an increase in biogas production, and the use of fermentation in the microbiological treatment of poultry litter seems to have negatively influenced production of biogas.     

Prioritizing islands for the eradication of invasive vertebrates in the United Kingdom overseas territories

Invasive alien species are one of the primary threats to native biodiversity on islands worldwide. Consequently, eradicating invasive species from islands has become a mainstream conservation practice. Deciding which islands have the highest priority for eradication is of strategic importance to allocate limited resources to achieve maximum conservation benefit. Previous island prioritizations focused either on a narrow set of native species or on a small geographic area. We devised a prioritization approach that incorporates all threatened native terrestrial vertebrates and all invasive terrestrial vertebrates occurring on 11 U.K. overseas territories, which comprise over 2000 islands ranging from the sub‐Antarctic to the tropics. Our approach includes eradication feasibility and distinguishes between the potential and realistic conservation value of an eradication, which reflects the benefit that would accrue following eradication of either all invasive species or only those species for which eradication techniques currently exist. We identified the top 25 priority islands for invasive species eradication that together would benefit extant populations of 155 native species including 45 globally threatened species. The 5 most valuable islands included the 2 World Heritage islands Gough (South Atlantic) and Henderson (South Pacific) that feature unique seabird colonies, and Anegada, Little Cayman, and Guana Island in the Caribbean that feature a unique reptile fauna. This prioritization can be rapidly repeated if new information or techniques become available, and the approach could be replicated elsewhere in the world. Priorización de Islas para la Erradicación de Vertebrados Invasores en los Territorios Exteriores del Reino Unido     

The use of a natural coagulant (Opuntia ficus-indica) in the removal for organic materials of textile effluents

The goal of this study was to investigate the activity of the coagulant extracted from the cactus Opuntia ficus-indica (OFI) in the process of coagulation/flocculation of textile effluents. Preliminary tests of a kaolinite suspension achieved maximum turbidity removal of 95 % using an NaCl extraction solution. Optimization assays were conducted with actual effluents using the response surface methodology (RSM) based on the Box–Behnken experimental design. The responses of the variables FeCl₃, dosage, cactus dosage, and pH in the removal of COD and turbidity from both effluents were investigated. The optimum conditions determined for jeans washing laundry effluent were the following: FeCl₃ 160 mg L^?1, cactus dosage 2.60 mg L^?1, and pH 5.0. For the fabric dyeing effluent, the optimum conditions were the following: FeCl₃ 640 mg L^?1, cactus dosage 160 mg L^?1, and pH 6.0. Investigation of the effects of the storage time and temperature of the cactus O. ficus-indica showed that coagulation efficiency was not significantly affected for storage at room temperature for up to 4 days.     

Pancreatic and sacral agenesis in association with maternal diabetes mellitus: Case report

Sacral agenesis was diagnosed sonographically in the fetus of a diabetic mother and pancreatic agenesis was found additionally at autopsy.     

Potential of Hemidesmus indicus for phytoextraction of lead from industrially contaminated soils

Many sites in the industrial region of Kattedan near Hyderabad, Andhra Pradesh (AP), India are contaminated with high concentrations of lead. The use of plants to remove toxic metals from soils (phytoremediation) is emerging as a potential strategy for cost-effective and environmentally sound remediation of contaminated soils. We studied remediation of soils contaminated with lead using a lead hyperaccumulating plant, Hemidesmus indicus. The ability of this plant to accumulate lead in shoots and roots was studied with pot experiments. The results showed that accumulation was maximum in roots for the first 1-3 weeks and later for a contact period of three months, the accumulation rate was maximum in shoots. In addition we used various chelating agents such as EDTA, HEDTA, DTPA and CDTA to determine the best chemical modifier for efficient lead removal from contaminated soils. The effect on lead accumulation of plant in the presence of various metal co-ions was also studied. An attempt was made for the decontamination of lead from five different "Real-life" soils of Kattedan using H. indicus.     

Persistent organochlorines in the serum of the non-occupationally exposed New Zealand population

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and organochlorine pesticides were measured in the serum of a sample of the New Zealand population aged 15 years and older. This was the first study to obtain representative measures of PCDDs, PCDFs and PCBs in the adult population of an entire country. Serum samples were obtained in 1996-1997. Potentially occupationally exposed individuals were excluded. Serum samples were pooled according to stratification criteria for area of residence, ethnicity, age, and sex. Of the 80 possible strata, sufficient serum for chemical analysis was available for 60, to which 1,834 individual samples contributed. For the PCDDs and PCDFs, most 2,3,7,8-chlorinated congeners were measured in all strata, with a mean toxic equivalents concentration across all strata of 12.8 ng TEQ kg(-1) lipid. Seven PCB congeners were frequently measured, including the coplanar congeners #126 and #169, quantified in all strata. Of the pesticides and their metabolites, only beta-HCH, dieldrin and pp'-DDE were consistently detected across strata. There was a general trend of increasing concentration with age. There were no consistent differences between the sexes, or between people of Maori (the indigenous people of New Zealand) and non-Maori ethnicity. Concentrations of PCDDs and PCDFs tended to increase in a North-South direction, possibly reflecting greater levels of industrialization and population concentration, and concentrations of the pesticide products were highest in the South, possibly reflecting historical use patterns. Results were consistent with a recent study of concentrations of these compounds in the milk of first-time mothers.     

Enhancement of PAH biomineralization rates by cyclodextrins under Fe(III)-reducing conditions

Amendment of a soil slurry with low concentrations of a cyclodextrin, hydroxypropyl-beta-cyclodextrin (HPCD), (0.05-0.5 g l(-1)) increased the phenanthrene mineralization rate of a microbial consortium by 25% under Fe(III)-reducing conditions. Although a higher concentration (5.0 g l(-1)) resulted in a faster initial rate of mineralization, mineralization ceased after 25 days with maximum mineralization 17% lower than the control (no HPCD). At lower HPCD concentrations, mineralization was still taking place at day 76. Although pH should affect Fe(III) solubility, mineralization rates at pH 6.0 and 8.0 were comparable. Decreasing the temperature reduced the extent and rate of mineralization, but mineralization rates at 10 degrees C were still 60% of that obtained at 30 degrees C.