Social influences on expressed willingness to pay: results of a deliberative monetary valuation study in Colombia

Deliberative monetary valuation (DMV) methods can support environmental decision making by enabling the exchange of arguments and information to produce more democratic outcomes. The product of a valuation may be an array of expressions of willingness to pay (WTP) by individuals or a collectively agreed monetary value. Concerns have been raised, however, as to whether this product is an outcome of thoughtful and independent decision-making or influenced by social pressures to conform. Our study examines this issue and addresses concerns about the use of DMV, based on a public deliberation of forest conservation in Colombia. We analyzed the impacts of social conformity on WTP under two different decision scenarios: individual and collective. The results suggest that the impacts of social conformity are greater when a collective decision is required. These findings indicate that tensions between the differing goals of DMV could undermine its democratic promise.     

Role of Geographic Information System (GIS) in Watershed Simulation By Winvast Model

The uncertainty of modeling input will increase the simulation error, and this situation always happens in a model without user-friendly interface. WinVAST model, developed by the University of Virginia in 2003, treats an entire multi-catchment by a tree-view structure. Its extra computer programs can connect geographic information system (GIS). Model users can prepare all the necessary information in ArcGIS. Extracting information from GIS interface can not only decrease the inconvenience of data input, but also lower the uncertainty due to data preparation. The Daiyuku Creek and Qupoliao Creek in the Fei-tsui reservoir watershed in Northern Taiwan provided the setting for the case study reported herein. The required information, including slope, stream length, subbasin area, soil type and land-use condition, for WinVAST model should be prepared in a Microsoft Access database, which is the project file of WinVAST with extension mdb. In ArcGIS interface, when the soil layer, land-use layer, and Digital Elevation Model (DEM) map are prepared, all the watershed information can be created as well. This study compared the simulation results from automatically generated input and manual input. The results show that the relative simulation error resulting from the rough process of data input can be around 30% in runoff simulation, and even reach 70% in non-point source pollution (NPSP) simulation. It could conclude that GIS technology is significant for predicting watershed responses by WinVAST model, because it can efficiently reduce the uncertainty induced by input errors.     

Prediction of the effluent from a domestic wastewater treatment plant of CASP using gray model and neural network

When a domestic wastewater treatment plant (DWWTP) is put into operation, variations of the wastewater quantity and quality must be predicted using mathematical models to assist in operating the wastewater treatment plant such that the treated effluent will be controlled and meet discharge standards. In this study, three types of gray model (GM) including GM (1, N), GM (1, 1), and rolling GM (1, 1) were used to predict the effluent biochemical oxygen demand (BOD), chemical oxygen demand (COD), and suspended solids (SS) from the DWWTP of conventional activated sludge process. The predicted results were compared with those obtained using backpropagation neural network (BPNN). The simulation results indicated that the minimum mean absolute percentage errors of 43.79%, 16.21%, and 30.11% for BOD, COD, and SS could be achieved. The fitness was higher when using BPNN for prediction of BOD (34.77%), but it required a large quantity of data for constructing model. Contrarily, GM only required a small amount of data (at least four data) and the prediction results were analogous to those of BPNN, even lower than that of BPNN when predicting COD (16.21%) and SS (30.11%). According to the prediction, results suggested that GM could predict the domestic effluent variation when its effluent data were insufficient.     

The effects of two acanthocephalan parasites, Pomphorhynchus laevis and Polymorphus minutus, on pairing success in male Gammarus pulex (Crustacea: Amphipoda)

Parasites can decrease male mating success in host species in various ways, in particular by affecting male competitive ability for access to females. However, male-male competition can take different forms (i.e. interference vs exploitation competition) and which type of competition is most affected by parasites is not always clear. We investigated the influence of two acanthocephalan parasites Pomphorhynchus laevis and Polymorphus minutus on the pairing success of their intermediate host, Gammarus pulex, using field-based studies and complementary laboratory-based studies. We first studied male pairing success in the field using four large samples of paired and unpaired individuals collected at different dates. In three of the samples, the effects of size and parasite infection were significant, whereas for one sample only male size had a significant effect. There was no difference in size distributions between infected and uninfected gammarids. Large males were paired more often than smaller males, and uninfected males were paired more frequently than infected males, the pairing success of P. minutus-infected males being more severely affected than that of P. laevis-infected males. We then experimentally tested the ability to enter into precopula with a receptive female in the presence or absence of competitors. In competitive situations, the pairing success of P. laevis- and P. minutus-infected males was significantly lower than that of uninfected males, with pairing success being more affected in P. laevis-infected than in P. minutus-infected males. In the absence of competition, males infected with P. laevis were significantly less likely to enter into precopula compared with uninfected males and P. minutus-infected males, whereas there was no difference between uninfected and P. minutus-infected males in their inclination to pair with a receptive female. However, for both parasites, latency time to pair formation was significantly shorter for uninfected than for infected males. In a third experiment, we tested for a potential effect of vertical segregation on the pairing success of infected and uninfected males, but found no evidence for it. We conclude that infected males may be less competitive than uninfected males in competition by exploitation between males for females.     

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.     

The impact of semiconductor, electronics and optoelectronic industries on downstream perfluorinated chemical contamination in Taiwanese rivers

This study provides the first evidence on the influence of the semiconductor and electronics industries on perfluorinated chemicals (PFCs) contamination in receiving rivers. We have quantified ten PFCs, including perfluoroalkyl sulfonates (PFASs: PFBS, PFHxS, PFOS) and perfluoroalkyl carboxylates (PFCAs: PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA) in semiconductor, electronic, and optoelectronic industrial wastewaters and their receiving water bodies (Taiwan's Keya, Touchien, and Xiaoli rivers). PFOS was found to be the major constituent in semiconductor wastewaters (up to 0.13 mg/L). However, different PFC distributions were found in electronics plant wastewaters; PFOA was the most significant PFC, contributing on average 72% to the effluent water samples, followed by PFOS (16%) and PFDA (9%). The distribution of PFCs in the receiving rivers was greatly impacted by industrial sources. PFOS, PFOA and PFDA were predominant and prevalent in all the river samples, with PFOS detected at the highest concentrations (up to 5.4 μg/L).     

Ozone oxidation and aerobic biodegradation with spent mushroom compost for detoxification and benzo(a)pyrene removal from contaminated soil

The combination of ozonation and spent mushroom compost (SMC)-mediated aerobic biological treatment was investigated in the removal of benzo(a)pyrene from contaminated soil. The performances of the process alone and combined were evaluated in terms of benzo(a)pyrene removal efficiency, mineralization efficiency (as total organic carbon removal), and soil residual toxicity (phytotoxicity to Lepidium Sativum and toxicity to Vibrio fischeri). In spite of the removal efficiency (35%) obtained by SMC-mediated biological process as a stand-alone treatment, the combined process showed a benzo(a)pyrene concentration reduction higher than 75%; the best removal (82%) was observed after 10 min pre-ozonation treatment. In particular, ozonation improved the biodegradability of the contaminant, as confirmed by the increase of CO(2) production (close to 70% compared to the control), mineralization (greater than 60%) and bacterial density (which increased by two orders of magnitude). Moreover, according to phytotoxicity tests on L. Sativum, the aerobic biological process of pre-ozonated soil decreased toxicity. According to the results achieved in the present study, ozonation pre-treatment showed an high potential to overcome the limitation of bioremediation of recalcitrant compound, but it should be carefully operated in order to maximize PAH removal efficiency as well as to minimize soil residual toxicity which can result from the formation of the oxidation intermediates.     

Chemically coupled microwave and ultrasonic pre-hydrolysis of pulp and paper mill waste-activated sludge: effect on sludge solubilisation and anaerobic digestion

The effects of alkali-enhanced microwave (MW; 50–175 °C) and ultrasonic (US) (0.75 W/mL, 15–60 min) pretreatments, on solubilisation and subsequent anaerobic digestion efficiency of pulp and paper mill waste-activated sludge, were investigated. Improvements in total chemical oxygen demand and volatile suspended solids (VSS) solubilisation were limited to 33 and 39 % in MW pretreatment only (175 °C). It reached 78 and 66 % in combined MW–alkali pretreatment (pH 12?+?175 °C), respectively. Similarly, chemical oxygen demand and VSS solubilisation were 58 and 37 % in US pretreatment alone (60 min) and it improved by 66 and 49 % after US–alkali pretreatment (pH 12?+?60 min), respectively. The biogas yield for US 60 min–alkali (pH 12)-pretreated sludge was significantly improved by 47 and 20 % over the control and US 60 reactors, respectively. The biogas generation for MW (150 °C)–alkali (pH 12)-pretreated sludge was only 6.3 % higher than control; however, it was 8.3 % lower than the MW (150 °C) reactor, which was due to the inhibition of anaerobic activity under harsh thermal–alkali treatment condition.     

Toxic effects of four sulphonylureas herbicides on soil microbial biomass

The effect of four triazinyl-sulfonylurea herbicides (cinosulfuron, prosulfuron, thifensulfuron methyl, triasulfuron) on soil microbial biomass, soil respiration, metabolic activity, metabolic quotient, and some enzymatic activities (acid and alkaline phosphatase, β-glucosidase, arylsulphatase, and fluorescein diacetate hydrolysis) were monitored under controlled conditions over 30 days. The herbicides were applied at the normal field dose (FD) and at ten-fold (10 FD) the field dose, in order to mimic a long term toxic effect. The measured soil microbial parameters showed that the FD had slight effects on soil microflora, while at 10 FD the tested herbicides exerted a stronger detrimental effect on soil microbial biomass and its biochemical activities.