Analysis of extinction in ultraviolet and visible spectra of water bodies of the Paraguay and Brazil wetlands

The extinction spectra in ultraviolet and visible radiation were analyzed using filtered and unfiltered water samples obtained in 11 open water bodies in the Neembucù (Paraguay) and Pantanal (Brazil) wetlands. The role of dissolved and suspended matter in the total extinction was analyzed between 260 nm and 700 nm. The chromophoric dissolved organic matter (CDOM) was the major component in extinction of considered ultraviolet radiation (260-400 nm). The differences in CDOM concentrations explained the main pattern of extinction of the ultraviolet radiation in the samples. Nevertheless, differences between the studied water bodies were found also to depend on the rate of photodegradation and photobleaching. The methodology developed in the present study was to distinguish "humic optic waters" according to quantity and quality of dissolved and suspended matter present. In the "humic optic water", the penetration of 10% of incident UV radiation and the photoactive layer are estimated. The influence of particulate matter increases in the total extinction of the wavelengths higher than 400 nm. The integral of the extinction curve of suspended matter in the visible wavelengths (400-700 nm) was found to relate with the total suspended solids and chlorophyll concentrations.     

Comparison of microwave assisted extraction with conventional (homogenization, vortexing) for the determination of incurred salinomycin in chicken eggs and tissues

Incurred and fortified salinomycin residues were extracted from chicken tissues and eggs by homogenization, vortexing and by microwave assisted extraction. The salinomycin residues were quantitated by liquid chromatography following postcolumn derivatization with either vanillin or 4-dimcthylamino-benzaldehyde and detected at 520 or 592 nm, respectively. Comparison of residue data indicated that microwave assisted extraction performed as well as the vortexing technique in extracting salinomycin residues in the tissues of laying chickens that were fed meal containing drugs at various level. In the present study, extracts from homogenizing could not be analyzed directly without clean up. Therefore, microwave assisted extraction appears to be a reliable, reproducible, and economical substitute for routinely used homogenization and vortexing extraction techniques.     

Effects of the mosquito larvicide GB-1111 on bird eggs

Golden Bear Oil (GB-1111; legal trade name for GB-1313) is a petroleum distillate used in the United States and other countries as a mosquito larvicide. As part of an evaluation of the potential effects of GB-1111 on birds, fertile eggs of mallards (Anas platyrhynchos) and bobwhite (Colinus virginianus) were incubated in the laboratory, and treated on day 4 of incubation with external applications equivalent to either 0, 1/3, 1, 3 or 10 times the maximum rate (X) of 47 l/ha (5 gal/A) of field application of GB-1111. Hatching success was significantly reduced in mallards treated at 3 and 10 times the maximum field application, with a calculated approximate LD50 of 1.9 times the maximum field application. Most mortality occurred within a week of treatment. Hepatic P450-associated monooxygenase activity (ethoxyresorufin-O-dealkylase; EROD) was negatively related to dose. In the 3X group there was a significant increase in the concentration of hepatic reduced glutathione (GSH) but a decrease in protein-bound thiols (PBSH). Hatching success of bobwhite was marginally reduced at the highest level of treatment (10X). Other effects at this level in bobwhite included a significant increase in incidence of abnormal embryos or hatchlings, lower body and liver weights, and a two-fold increase in hepatic microsomal EROD activity in hatchlings. The recommended maximum rate of field application of GB-1111 is unlikely to impair the survival or development of bobwhite embryos but is potentially toxic to mallard embryos under conditions of larvicide drift or spray overlap.     

Influence of plants on the methane emission from sediments

The previous theory [Chem. Global Change Sci. 3 (2001) 33; Chemosphere 50 (2003) 191] of methane emission is applied to vegetated sediments. The presence of roots in a sediment is taken into account. It is assumed that methane and nitrogen enter a sediment through channels existing in plants and roots. The rate of methane and nitrogen transport through plants and roots is proportional to the difference in concentrations in the layer and on the upper surface. It is established that as the vegetation density increases, the rate of methane transport increases so that with sufficient vegetation density, almost all methane passes to the atmosphere through plants. In this case, the value of bubble emission decreases to zero. The nitrogen transport rate through plants first increases and then decreases with increasing the vegetation density. The theory qualitatively and quantitatively describes the dependence of methane concentration on depth in the presence of plants. A comparison with the available experimental data on dissolved methane concentration and bubble composition indicates satisfactory agreement.     

BETR-World: a geographically explicit model of chemical fate: application to transport of alpha-HCH to the Arctic

The Berkeley-Trent (BETR)-World model, a 25 compartment, geographically explicit fugacity-based model is described and applied to evaluate the transport of chemicals from temperate source regions to receptor regions (such as the Arctic). The model was parameterized using GIS and an array of digital data on weather, oceans, freshwater, vegetation and geo-political boundaries. This version of the BETR model framework includes modification of atmospheric degradation rates by seasonally variable hydroxyl radical concentrations and temperature. Degradation rates in all other compartments vary with seasonally changing temperature. Deposition to the deep ocean has been included as a loss mechanism. A case study was undertaken for alpha-HCH. Dynamic emission scenarios were estimated for each of the 25 regions. Predicted environmental concentrations showed good agreement with measured values for the northern regions in air, and fresh and oceanic water and with the results from a previous model of global chemical fate. Potential for long-range transport and deposition to the Arctic region was assessed using a Transfer Efficiency combined with estimated emissions. European regions and the Orient including China have a high potential to contribute alpha-HCH contamination in the Arctic due to high rates of emission in these regions despite low Transfer Efficiencies. Sensitivity analyses reveal that the performance and reliability of the model is strongly influenced by parameters controlling degradation rates.     

Polychlorinated biphenyls and chlorinated pesticides in mussels from the Egyptian Red Sea coast

The residues of 17 organochlorine pollutants were analyzed in bivalve Brachiodontes sp. collected from 11 different locations in April 2000 along the Egyptian Red Sea coast. The pollutants studied were 10 individual polychlorinated biphenyl (PCB) congeners, alpha,alpha,alpha-hexachlorocyclohexane (HCHs), cyclodienes (heptachlor, heptachlorepoxide, aldrin, dieldrin) and dichlorodiphenyltrichloroethanes (DDTs) (p,p'-DDE, p,p'-DDD and p,p'-DDT). The concentration of total DDTs ranged between 125 and 772 ng/g of wet weight whereas the concentration of the PCBs, HCHs and cyclodienes ranged from 6.7 to 66.4 ng/g; 16.2 to 183.4 ng/g and 8.8 to 221.6 ng/g of wet weight, respectively. The levels are low to moderate in relation to the published data from other coastal areas. The present results indicate low to moderate PCBs and pesticides contamination in the investigated mussels except DDTs.     

Calculating pesticide sorption coefficients (Kd) using selected soil properties

Pesticide soil/solution distribution coefficients ( Kd values), commonly referred to as pesticide soil sorption values, are utilized in computer and decision aid models to predict soil mobility of the compounds. The values are specific for a given chemical in a given soil sample, normally taken from surface soil, a selected soil horizon, or at a specific soil depth, and are normally related to selected soil properties. Pesticide databases provide Kd values for each chemical, but the values vary widely depending on the soil sample on which the chemicals were tested. We have correlated Kd values reported in the literature with the reported soil properties for an assortment of pesticides in an attempt to improve the accuracy of a Kd value for a specific chemical in a soil with known soil properties. Mathematical equations were developed from regression equations for the related properties. Soil properties that were correlated included organic matter content, clay mineral content, and/or soil pH, depending on the chemical properties of the pesticide. Pesticide families for which Kd equations were developed for 57 pesticides include the following: Carboxy acid, amino sulfonyl acid, hydroxy acid, weakly basic compounds and nonionizable amide/anilide, carbamate, dinitroaniline, organochlorine, organophosphate, and phenylurea compounds. Mean Kd values for 32 additional pesticides, many of which had Kd values that were correlated with specific soil properties but for which no significant Kd equations could be developed are also included.     

Treatment and detoxification of a sanitary landfill leachate

The leachate from an old sanitary landfill (Gramacho Metropolitan Landfill, Rio de Janeiro) was characterized and submitted to coagulation and flocculation treatment followed by ozonation and ammonia stripping. The performance of the treatment was assessed by monitoring the removal of organic matter (COD and TOC), ammonium nitrogen and metals. Detoxification was assessed by determining acute toxicity, using the following organisms: Vibrio fisheri, Daphnia similis, Artemia salina and Brachydanio rerio. Membrane fractionation was employed to infer the range of molecular masses of the pollutants found in the effluent, as well as the toxicity associated to these fractions. Of the techniques under investigation, coagulation and flocculation followed by ammonia stripping were the most effective for toxicity and ammonium nitrogen removal. Membrane fractionation was effective for COD removal; however, acute toxicity was almost the same in all the fractionated samples. Ozonation was moderately effective for COD removal, but significant toxicity removal was only attained when high ozone doses were used.     

Evaluation of relative photonic efficiency in heterogeneous photocatalytic reactors

The evaluation of photonic efficiency in heterogeneous photocatalysis remains elusive because the number of absorbed photons is difficult to assess experimentally. The photonic efficiency of heterogeneous photocatalytic reactors depends on the reactor geometry, irradiation source, and photocatalyst properties. In this work, the relative photonic efficiency of heterogeneous photocatalytic reactors to degrade an azo dye was evaluated using phenol as the standard system. The experimental tests were carried out in a batch reactor under different conditions of pH, catalyst dosage, initial concentration, and ultraviolet (UV) lamps. The kinetics of disappearance of both phenol and azo dye were studied using the initial rate method and were described according to the Langmuir-Hinshelwood (L-H) kinetic model. It was observed that the relative photonic efficiency depends on the adsorption/desorption properties of the photocatalyst.     

Haematological and biochemical effects of polyphenolics in animal models

Polyphenols of natural and synthetic origin are exploited in tanning sector to convert putrescible skin/hide to non-putrescible leather. However, only 30-40% of the inputs have been taken up for processing, the remaining is released as unspent. The existing conventional wastewater treatment systems are inefficient in removing or degrading these unspent polyphenols and thus detrimental to ecosystem. The present study demonstrates the evaluation of impact of both synthetic and natural polyphenols on biochemical and haematological properties of blood and serum in animal models. The results reveal that concentrations of polyphenols play a major role. At higher concentrations, irrespective of their nature, there was a marked change in the lipid profile (81% reduction), followed by insignificant change in glucose levels, RBC and WBC counts and other haematological parameters. At lower concentrations, no significant changes in the above said properties were observed.