Parathion degradation and its intermediate formation by Fenton process in neutral environment

The purpose of this study is to investigate parathion degradation by Fenton process in neutral environment. The initial parathion concentration for all the degradation experiments was 20 ppm. For hydrogen ion effect on Fenton degradation, the pH varied from 2 to 8 at the [H₂O₂] to [Fe²⁺] ratio of 2-2 mM, and the result showed pH 3 as the most effective environment for parathion degradation by Fenton process. Apparent degradation was also observed at pH 7. The subsequent analysis for parathion degradation was conducted at pH 7 because most environmental parathion exists in the neutral environment. Comparing the parathion degradation results at various Fenton dosages revealed that at Fe²⁺ concentrations of 0.5, 1.0 and 1.5 mM, the Fenton reagent ratio ([H₂O₂]/[Fe²⁺]) for best-removing performance were found as 4, 3, and 2, resulting in the removal efficiencies of 19%, 48% and 36%, respectively. Further increase in Fe²⁺ concentration did not cause any increase of the optimum Fenton reagent ratio for the best parathion removal. The result from LC-MS also indicated that hydroxyl radicals might attack the PS double bond, the single bonds connecting nitro-group, nitrophenol, or the single bond within ethyl groups of parathion molecules forming paraoxons, nitrophenols, nitrate/nitrite, thiophosphates, and other smaller molecules. Lastly, the parathion degradation by Fenton process at the presence of humic acids was investigated, and the results showed that the presence of 10 mg L⁻¹ of humic acids in the aqueous solution enhanced the parathion removal by Fenton process twice as much as that without the presence of humic acids.     

Photoelectrocatalytic degradation of 4,4'-dibromobiphenyl in aqueous solution on TiO₂ and doped TiO₂ nanotube arrays

Polybrominated biphenyls have been widely used as flameretardants in textile and electronic industries, and additives in plastics. Over the past few decades, much attention has been given to polybrominated biphenyls in the environment and their effects on humans. In this paper, we studied on the degradation of 4,4′-dibromobiphenyl, a typical one of polybrominated biphenyls, through photoelectrocatalytic process with TiO₂, Zr/TiO₂ and Zr, N/TiO₂ nanotube arrays. The results showed that the photoelectrocatalytic process was more efficient than photocatalytic and electrolytic process alone. The results exhibited that the photoelectrocatalytic efficiency was significantly affected by the properties of the catalysts and bias potential, and the highest photoelectrocatalytic degradation rate was achieved with Zr, N/TiO₂ at 1 V and the order was Zr, N/TiO₂ > Zr/TiO₂ > TiO₂. The mechanism was also discussed by detecting the changes of pH value, bromine anion, total organic carbon and intermediates during the process.     

Determination and partitioning behavior of perfluoroalkyl carboxylic acids and perfluorooctanesulfonate in water and sediment from Dianchi Lake, China

Perfluorinated compounds (PFCs) have received much attention on their distribution in various matrices including water bodies, precipitations, sediment and biota in different areas globally, however, little attention has been paid to their occurrence and distribution in urban lakes. In this study, water and sediment samples collected from 26 sites in Dianchi Lake, a plateau urban lake in the southwestern part of China were analyzed via high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for ten analytes involving nine perfluoroalkyl carboxylic acids (PFOAs) and perfluorooctanesulfonate (PFOS). Total levels of PFCs were 30.98 ± 32.19 ng L(-1) in water and 0.95 ± 0.63 ng g(-1) in sediment. In water samples PFOA was the dominant PFC contaminant, with concentrations ranging from 3.41 to 35.44 ng L(-1), while in sediments PFOS was the main PFC contaminant at levels from 0.07-0.83 ng g(-1) dry weight. Field-based sediment water distribution coefficients (K(D)) were calculated and corrected for organic carbon content (K(oc)), which reduced variability among samples. The log K(oc) ranged from 2.54 to 3.57 for C8-C12 perfluorinated carboxylic acids, increasing by 0.1-0.4 log units with each additional CF2 moiety. The log K(oc) of PFOS was 3.35 ± 0.32. Magnitudes and trends in log K(D) or log K(oc) appeared to agree well with previously published laboratory data. Results showed that different PFC composition profiles were observed for samples from the lake water and sediments, indicating the presence of dissimilar characteristics of the PFCs compounds, which is important for PFC fate modeling and risk assessment.     

Forest Value Orientations in Australia: An Application of Computer Content Analysis

This article explores the expression of three forest value orientations that emerged from an analysis of Australian news media discourse about the management of Australian native forests from August 1, 1997 through December 31, 2004. Computer-coded content analysis was used to measure and track the relative importance of commodity, ecological and moral/spiritual/aesthetic forest value orientations. The number of expressions of these forest value orientations followed major events in forest management and policy, with peaks corresponding to finalization of Regional Forest Agreements and conflicts over forest management. Over the time period analyzed, the relative share of commodity value orientation decreased and the shares of the ecological and moral/spiritual/aesthetic value orientations increased. The shifts in forest value orientations highlight the need for native forests to be managed for multiple values and the need for continued monitoring of forest values. Research carried out while employed by the Bureau of Rural Sciences, Department of Agriculture, Fisheries, Forestry, Canberra, Australia.     

Effect of filter-feeding fish silver carp on phytoplankton species and size distribution in surface water： A field study in water works

Silver carp were introduced into the pre-sedimentation pond to control excessive phytoplankton in raw water.The effectiveness of the filter-feeding silver carp on phytoplankton control and the effect of silver carp on phytoplankton community were investigated.The results showed that Microcystis could be effectively removed by silver carp stocked in the pre-sedimentation pond,and simultaneously,the concentration of single-cell phytoplankton increased obviously.The difference in phytoplankton species and singlecell phytoplankton size between in the water and in the gut of silver carp indicated that phytoplankton smaller than 5 μm,such as Chamydomonas and Platymonas,were almost not be filtered by silver carp,phytoplankton with the size between 5 and 20 μm could be partly filtered,and large size phytoplankton,mainly colony-forming Microcystis could be filtered almost completely.These filterfeeding characteristics directly caused the phytoplankton size distribution biased toward miniaturization.Therefore,this biological treatment using silver carp could be applied only to deal with groups of Microcystis-dominated eutrophic water,and was not appropriate in water bodies where single-cell micro phytoplankton were dominant.Especially when silver carp are used in water treatment,a cautious attitude should be taken based on the evaluation of phytoplankton biomass and species structure features in raw water.     

Road transport and urban air quality in China

１　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＣｈｉｎｅｓｅｇｏｖｅｒｎｍｅｎｔｈａｓｔａｋｅｎｔｈｅａｕｔｏｍｏｂｉｌｅｉｎｄｕｓｔｒｙａｓｏｎｅｏｆｉｔｓｐｉｌｌａｒｉｎｄｕｓｔｒｉｅｓｏｆＣｈｉｎａ．Ｔｈｅｃｕｒｒｅｎｔｐｅｒｃｅｎｔａｇｅｏｆａｕｔｏｍｏｔｉｖｅｔｒａｎｓｐｏｒｔａｔｉｏｎｏｆｐａｓｓｅｎｇｅｒｓｉｓ４５％,ｗｈｉｌｅｔｈａｔｏｆｃａｒｇｏｉｓａｐｐｒｏｘｉｍａｔｅｌｙ１５％．Ａｕｔｏｍｏｂｉｌｅｎｏｗｐｌａｙｓａｍｏｒｅｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｓｈｏｒｔｒａｎｇｅｔｒａｎｓ…     

A generalized fuzzy linear programming approach for environmental management problem under uncertainty

In this study, a generalized fuzzy linear programming (GFLP) method was developed to deal with uncertainties expressed as fuzzy sets that exist in the constraints and objective function. A stepwise interactive algorithm (SIA) was advanced to solve GFLP model and generate solutions expressed as fuzzy sets. To demonstrate its application, the developed GFLP method was applied to a regional sulfur dioxide (SO2) control planning model to identify effective SO2 mitigation polices with a minimized system performance cost under uncertainty. The results were obtained to represent the amount of SO2 allocated to different control measures from different sources. Compared with the conventional interval-parameter linear programming (ILP) approach, the solutions obtained through GFLP were expressed as fuzzy sets, which can provide intervals for the decision variables and objective function, as well as related possibilities. Therefore, the decision makers can make a tradeoff between model stability and the plausibility based on solutions obtained through GFLP and then identify desired policies for SO2-emission control under uncertainty.     

Evaluation of Al30 polynuclear species in polyaluminum solutions as coagulant for water treatment

Polyaluminum coagulant with a content of 76.8% of Al30 (PACAl30) was prepared. Its coagulation behaviors were compared with high Al13 content polyaluminum coagulant (PACAl13) and AlCl3. The species stability was studied using Al-Ferron method and 27Al NMR. The coagulation performances were investigated by studying the rate of flocs development, the turbidity removal efficiency and charge neutralization capacity under fixed pH conditions and uncontrolled pH conditions. The effect of pH on coagulation was also studied. The results show that PACAl30 are stable for using as coagulant. PACAl30 causes less pH depression than PACAl13. The charge neutralization capacity of PACAl30 is slightly lower than that of PACAl13 at pH6.8 and higher at pH 6.5. PACAl30 achieves the most effective turbidity removal in these three coagulants. And it acts effectively within a much broader dosage range and a wider pH range when compared with PACAl13. PACAl30 achieves the highest turbidity removal due to its strong flocs formation capacity. The results verify that Al30 is another highly active coagulation/flocculation species for turbidity removal.     

A screen-printed, amperometric biosensor for the determination of organophosphorus pesticides in water samples

An amperometric biosensor based on screen-printed electrodes (SPEs) was developed for the determination of organophosphorus pesticides in water samples. The extent of acetylcholinesterase (AChE) deactivation was determined and quantified for pesticide concentrations in water samples. An enzyme immobilization adsorption procedure and polyacrylamide gel matrix polymerization were used for fabrication of the biosensor, with minimal losses in enzyme activity. The optimal conditions for enzyme catalytic reaction on the SPEs surfaces were acetylthiocholine chloride (ATChCl) concentration of 5 mmol/L, pH 7 and reaction time of 4 min. The detection limits for three organophosphorus pesticides (dichlorvos, monocrotophs and parathion) were in the range of 4 to 7 g/L when an AChE amount of 0.1 U was used for immobilization.