Removal of chloride from ethylene glycol solution using alumina/zeolite membrane as a physical boundary between the organic and aqueous phases

The permeation of Cl^? ions from a NaCl/ethylene glycol (EG) solution during electrodialysis was investigated using alumina and alumina/zeolite membranes. Voltage changes had very little effect on Cl^? permeation through the alumina membrane, suggesting that the driving force for the permeation was concentration-gradient-induced diffusion, and not the electric field. Solvation of the Na⁺ ions by EG resulted in EG migration through the membrane. Replacement of the deionized water (electrolyte) in the anodic cell with NaOH resulted in increased Cl^? permeation, although a greater amount of EG migrated into the NaOH solution as well. No notable difference was observed in Cl^? permeation through the alumina and alumina/zeolite membranes, but EG migration decreased when using the latter membrane, suggesting that EG migration was prevented by the zeolite layer. The proposed alumina/zeolite membrane is, hence, useful for solvent recovery by electrodialysis, but its mechanical stability must be improved for industrial applications.     

Application of water quality indices and analysis of the surface water quality monitoring network in semiarid North-Central Chile

Surface water quality has increasing importance worldwide and is particularly relevant in the semiarid North-Central Chile, where agriculture and mining activities are imposing heavy pressure on limited water resources. The current study presents the application of a water quality index in four watersheds of the 29°-33°S realm for the period 1999-2008, based on the Canadian Council of Ministers for the Environment approach and the Chilean regulation for irrigation water quality. In addition, two modifications to the index are tested and a comprehensive characterization of the existing monitoring network is performed through cluster analysis. The basins studied show fairly good water quality in the overall, specially the Limarí basin. On the other hand, the lower index values were obtained for the headwaters of Elqui, associated with the El Indio mining district. The first modification of the indicator (i.e., to consider parameters differentially according to their effect on human health or the environment) did not produce major differences with respect to the original index, given the generally good water quality. The second modification (i.e., to consider as threshold values the more restrictive figures derived from a set of regulations) yielded important differences in the indicator values. Finally, an adequate characterization of the monitoring network was obtained. The results presented spatial coherence and the information can be used as a basis for the optimization of the monitoring network if required.     

Electrodialysis for NaCl/EG solution using ion-exchange membranes

A new concept for the recycling of poly(vinyl chloride) (PVC) has been introduced, including the dehydrochlorination of PVC in ethylene glycol (EG) with NaOH as a reactant, the subsequent separation of NaCl from EG by electrodialysis, and the recovery of chlorine for the synthesis of new PVC. In this work, the separation of NaCl by electrodialysis was investigated. About 98 % of the salt were recovered from EG, with less than 10 % of the EG permeating the membranes after 5 h.     

Relative bioavailability of tropical volcanic soil-bound chlordecone in laying hens (Gallus domesticus)

The former use of chlordecone (CLD) in the French West Indies has resulted in long-term pollution of soils and of food chains. CLD may be transferred into eggs of hens reared outdoors, through polluted soil ingestion. Tropical volcanic soils display variable capacities of pollutant retention: CLD is less available and more persistent in andosol than in nitisol. The impact of soil type on CLD bioavailability to hens was tested through a relative bioavailability study. The deposition of CLD in egg yolk and in abdominal fat was measured in 42 individually housed laying hens fed with diets containing graded levels of CLD from polluted andosol, nitisol, or spiked oil during 23 days. Within each ingested matrix, the concentration of CLD in yolk and in abdominal fat linearly increased with the amount of ingested CLD (P < 0.001). However, the response to andosol diets and to nitisol diets was not different from the response to oil diets (P > 0.1), indicating that CLD was equally bioavailable to laying hens, irrespective of the matrix. This suggests that the hen's gastrointestinal tract efficiently extracts CLD from the two tropical volcanic soils, regardless of their retention capacity. Thus, hens reared on polluted soils with CLD may lay contaminated eggs.     

Toxicity of Selected Pharmaceuticals to the Anostracan Crustacean Thamnocephalus platyurus - Comparison of Sublethal and Lethal Effect Levels with the 1h Rapidtoxkit and the 24h Thamnotoxkit Microbiotests

- DOI: http://dx.doi.org/10.1065/espr2006.01.005 Background, Aims and Scope In view of the limited amount of information on the potential hazard of the ever increasing amounts of drugs in surface waters to aquatic biota, a study was undertaken to determine the effect levels of 28 selected pharmaceuticals to the crustacean test species Thamnocephalus platyurus. The drugs belong to 5 different groups: non steroidal anti-inflammatory agents, biocides, cardiovascular compounds, nervous system drugs and purine alkaloids. Methods Toxicity tests were carried out with the 1h Rapidtoxkit and the 24h Thamnotoxkit microbiotests in order to make a comparison of sublethal effects (visible as stress through absence of feeding) measured after a very short time of exposure (1h) and lethal effects after prolonged exposure (24h). Dilution series starting at 200 mg l–1 were prepared and applied, and median effects levels were calculated and transformed into Toxic Units (TU) for easy data comparison. Results and Discussion The toxic effects found have been ranked into 4 arbitrary toxicity classes: not toxic (TU<0.2), low toxicity (0.2<TU<1.0), toxic (1.0<TU<10) and very toxic (TU>10). The toxicity levels noted ranged from virtually no effects for a few of the pharmaceuticals, at the highest concentration tested out, to LC50's below 1 mg l–1 (>100 TU) for 3 nervous system drugs (Amitryptiline, Thioridazine and Chlorpromazine). According to the toxicity classification, 17 of the 28 compounds (i.e. 67%), belong to the same class for the lethal and the sublethal tests. More pronounced differences in effect levels between the two assays were observed mainly for the pharmaceuticals which were either not toxic or only slightly toxic at the 200 mg l–1 level. For 90% of the toxic drugs the ratio between the toxicity values for both tests is below 5. Conclusion An overall correlation coefficient of 0.96 was found between the 2 microbiotests, confirming the good predictive potential of the 1h stress-based Rapidtoxkit in revealing important biological effects (mortality) after more prolonged exposure of the crustacean test species to chemical compounds. Recommendation and Outlook The present study clearly shows that new microbiotests such as the 1h Rapidtoxkit and the 24h Thamnotoxkit are attractive tools for rapid cost-effective screening of 'new' pollutants such as drugs which may threaten the biological communities of the aquatic environment.     

PCB and dioxin-like PCB in indoor air of public buildings contaminated with different PCB sources--deriving toxicity equivalent concentrations from standard PCB congeners

Data on dioxin-like PCB in indoor air of buildings with PCB-containing materials and on possible correlation between toxicity equivalent concentrations (TEQ) and levels of non-dioxin-like standard PCB is sparse. As part of a larger survey on indoor-air contamination with PCB, the connection between the concentration of standard PCB congeners and the dioxin-like toxicity expressed as TEQ was investigated. Indoor air samples (n=8) were collected in four public buildings with known PCB sources and total PCB levels in the range from 715 to 2250 ng/m3 and analyzed for the six non-dioxin-like standard PCB (congeners 28, 52, 101, 138, 153, 180), the twelve dioxin-like PCB congeners according to WHO and the 17 2,3,7,8-substituted PCDD/PCDF congeners. In three buildings where PCB were used as flame retardant coatings of acoustic ceiling tiles, PCB 101 had the maximum level among the six standard PCB, while in the building with permanent elastic sealants as PCB source, congeners 28 and 52 dominated the pattern by far. In the case of permanent elastic sealants as PCB source (n=3) a total PCB concentration of 1000 ng/m3 corresponded to a total TEQ level of 0.3-0.6 pg/m3. In contrast, in rooms with acoustic ceiling tiles as PCB source, 1.8-4.7 pg TEQ/m3 per 1000 ng total PCB/m3 were found. Linear regression analysis between PCB and TEQ indicated that PCB 118 might be used to calculate the total TEQ of dioxin-like PCB and PCDD/PCDF. By means of such a correlation it is possible to estimate TEQ by extrapolation from the results of less sophisticated analytical methods. It is tentatively recommended to use PCB 118 for screening purposes or re-evaluation of standard PCB indoor-air measurements. If only the six non-dioxin-like PCB standard congeners are available, a regression algorithm using the sum of PCB 101, 138, 153 and 180 might be used instead.     

Effects of the parasiticide ivermectin on the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata

Although widely used for the treatment of endo- and ectoparasites in livestock and pets, very few data on chronic effects on aquatic organisms are available for the parasiticide ivermectin. In the present study, toxicity of ivermectin to two freshwater organisms, the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata was investigated. For D. magna, a mean LC(50) 48 h of 5.7 ngl(-1) was derived from 10 acute tests. Chronic toxicity of ivermectin to D. magna was extremely high: with 0.001 and 0.0003 ngl(-1), respectively, nominal LOEC and NOEC based on growth and reproduction were far below the analytical limit of detection for this compound. P. subcapitata was considerably less sensitive to ivermectin than D. magna. For both growth rate and yield, EC(50) was >4,000 microgl(-1), LOEC was 1,250 microgl(-1) and NOEC 391microgl(-1). In view of the high toxicity to D. magna, the use of ivermectin might pose a risk to local aquatic ecosystems. Further studies should be carried out to investigate the effects of ivermectin and its degradation products on pelagic and benthic freshwater invertebrates.     

Irrigation pricing policies and its impact on agricultural inputs demand in Tunisia: a DEA-based methodology

This paper estimates farmers' individual irrigation water demand functions employing the information hidden in individual farmers' technical efficiency. This information is extracted through the development of a new deductive methodology based on inverse Data Envelopment Analysis (DEA) models. The empirical results for Tunisia show that farmers who are more technically efficient have less elastic irrigation water demand functions; these farmers would adjust demand only to a limited extent and they can afford the water price. In contrast, water pricing significantly affects those that are less efficient. These farmers shift towards a different cropping pattern using significantly less water and more land when the price of water increases. Thus, higher water prices would threaten this category's livelihood if their efficiency is not improved. However, if the technical efficiency of these farmers were to improve, then it would be more difficult to reach water saving objectives since their demand will also become highly inelastic. The findings have important implications in view of the objectives of Tunisia water policy which include:full cost recovery, continuity of the irrigation activity, and water saving at the national level.     

A rapid,simple screening toxicity test using desiccated bdelloid rotifers: Rotifer Activity Inhibition Test (RAIT)

Environmental Science and Pollution Research - A protocol for an ultra-rapid screening toxicity test is described using the rotifer Philodina acuticornis/roseola. The test can be executed in 30 min...     

Nucleophilic substitution of poly(vinyl chloride) with iminoacetic acid and n-dodecanethiol

The modification of poly(vinyl chloride) was carried out with iminodiacetic acid (IDA, C₄H₇NO₄) and iminodiacetic acid dimethylester (IDADM, C₆H₁₁NO₄), as well as with n-dodecanethiol (DT, C₁₂H₂₆S) in the presence of K₂CO₃. The reaction was carried out at different temperatures below 100 °C with dimethyl formamide (DMF) and cyclohexanone as solvents. IDA did not show any reactivity, probably due to the dipolar character of the molecule. IDADM caused the elimination of HCl, while only substitution ratios of about 3 % were observed. However, the modification of PVC with DT resulted in a substitution rate of 18 % without elimination. DT-PVC showed excellent thermal properties, comparable with those of the unmodified polymer.