Mass transport of organic contaminants through a self-sealing/self-healing mineral landfill liner

The self-sealing/self-healing (SS/SH) liner system is based on the fundamental principle that an impermeable seal is self-formed and self-healed by the pozzolanic reaction at the interface between two adjacent reactive layers. The objectives of this study were to evaluate the effect of contaminants on the performance of an SS/SH liner used as a hydraulic barrier, to understand mechanism of volatile organic compound (VOC) sorption on the SS/SH materials, and to estimate the mass transport parameters of contaminants through the SS/SH liner materials. The hydraulic conductivity of the liner material decreased continuously with time, and stabilized at less than 1 × 10^–7cm/s after approximately 15 days. It is known that the seal at the interface between two reactive layers is self-formed over time, and this contributes to the decrease in the hydraulic conductivity of such a liner system. The retardation of the seven target VOCs tested was greater in the SS/SH liner materials than in a clayey soil specimen owing to the higher sorption capacity. An analytical solution developed to test column equipment could reduce the time required to estimate the hydrodynamic dispersion coefficients of organic compounds by using the data on changes in concentration in the upper reservoir of the column.     

Formation and Transport of Atmospheric Aerosol over Athens, Greece

The effects of meteorology on ambient aerosol concentrations and aerosol transport, within the Greater Athens Area during the summer period, was investigated. Measurements of size fractionated anions and cations were made at two sites (inland at Ag. Stefanos and on the coast at Pireas) within the Greater Athens Area. The wind regime exhibited a distinctinfluence such that the sea-breeze circulation strongly enhanced the formation of secondary aerosols. For sulphate the difference in concentration between the two sites was,on average, 8 times greater on sea-breeze days compared with Etesian days (warm days with NE winds). During `normal' days,any differences in concentrations were possibly due to localemissions. Elevated concentrations in the fine mode were detectedat both sites during the sea-breeze days. The sea-breezecirculation enhances the development of secondary aerosolswhich was clearly shown at the inland site. Nitrous acid,hydrochloric acid and particulate nitrate, sulphate andammonium increase during sea-breeze days. Elevated levelsof nitrate, 4 m diameter, were particularly observedon the days with a strong sea-breeze circulation. Sulphatewas well correlated with both sulphur dioxide and ammoniumsuggesting the production of NH₄HSO₄/(NH₄)₂SO₄ aerosols, formedthrough the neutralisation of NH₃ with sulphuric acids.Ammonium sulphate was found to be the major ammoniumcomponent in Athens.     

A phytoremediation study: Selection of tropical and other vascular plants for decolorization of Poly R‐478 dye

Peroxidases and other lignin‐degrading enzymes and chemicals can potentially degrade persistent pollutants. Fifty vascular plant species were hydroponically tested for the capability of decolorization of Poly R‐478, a lignolytic indicator dye. The top six species that had less than 50 percent of control color at the end of the experiments were Pennisetum purpureum, Rumex crispus, Fimbristylis cymosa, Eleocharis calva, Hibiscus furcellatus, and Cyperus javanicus, in an order from high to low decolorization activity. F. cymosa, E. calva, and C. javanicus are in the Cyperaceae family. Extracellular peroxidase activity was found in vascular plants and correlated to decolorization of polymeric dyes. The plant R. crispus provided the highest guaiacol peroxidase enzyme activity among four of the top six plant species. The Poly R‐478 decolorization could be used as a fast screening technique for vascular plants that may have phytoremediation capability. © 2006 Wiley Periodicals, Inc.     

Robust Prioritization of Climate Change Adaptation Strategies Using the VIKOR Method with Objective Weights

This study proposes a robust prioritization framework for climate change adaptation strategies under uncertain climate change scenarios, using the VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) method, a multi‐criteria decision‐making approach, together with the Shannon entropy‐based weights. The VIKOR method allows us to find a compromise solution between two decision strategies of maximizing group utility and minimizing individual regret, and the Shannon entropy is used to determine objective weights among multiple climate change scenarios. The proposed methodology was applied to the problem of selecting locations of subwatersheds for reusing treated wastewater (TWW) in a Korean urban watershed. Selected based on the sustainability concept, hydro‐environmental and socioeconomic indicators were used to evaluate the sustainability of TWW reuse under multiple climate change scenarios, using the hydrologic simulation model results and statistical data. Finally, sustainability scores under multiple scenarios were aggregated using the VIKOR together with the Shannon entropy‐based weights for the robust prioritization of adaptation strategies. According to the different levels of regret aversion or affinity, our results for water quality showed different sets of adaptation strategies as the best options, suggesting that our framework would help stakeholders seeking the robust options considering both the utility and regret.     

Desorption characteristics of kaolin clay contaminated with zinc from electrokinetic soil processing

A number of bench scale laboratory column tests were carried out using a newly designed and developed electrokinetic cell to investigate the fundamental behavior of zinc-spiked kaolin clay subjected to an electric field. Laboratory investigations focused on (i) zinc migration by the combined effects of electromigration and electro-osmosis and (ii) the electrically induced desorption characteristics of zinc-contaminated kaolin that occurred during processing. The correlations of the applied voltage gradient, electro-osmotic flow rate, and the development of a pH gradient were examined and evaluated. The results showed that the removal efficiency was high during the early stage of processing due to rapid desorption by electrokinetic effects in the cathode region. However, the majority of zinc migrating from the anode was precipitated due to the high pH environment in the cathode region.     

Characterisation of particulate matter on the receptor level in a city environment

Airborne particulate matter (PM) has become one of the dominant pollutants with the increasing material and energy demand due to global economic growth. The main objective of this research is to provide a comprehensive receptor level characterisation of the particulate matter collected in a city environment. Particulate matter samples were collected on Tapered Element Oscillating Microbalance (TEOM) filters from five monitoring sites over a period of 1 year. An Andersen eight-stage cascade impactor was also used to collect airborne PM samples from three other locations to compare with the samples collected by TEOM. All the samples were then subjected to individual particle morphology and chemical composition analysis by SEM/EDS. Bulk chemical composition of the samples were also analysed through ICP–OES. Based on these analyses, possible sources of the PM samples were identified. The results showed that the monitoring sites in residential environments were dominated by transportation-derived particles and other migratory particulates. Monitoring sites near the city centre were dominant by particles from transportation, with biological particles abundant for the site closer to a river. The monitoring station located close to the industrial area, despite only 200 m away from a motorway, has low contribution of non-exhaust particulates from vehicles. Instead, the particulates collected from this site were dominated by industrial sources. An air dispersion modelling package was also used to model the particulate matter dispersion in the city area for the period of sampling. The results from the model showed that the points of high emissions were around industrial areas.     

Assessment of the school drinking water supply and the water quality in Pingtung County, Taiwan

In this study, a questionnaire survey of school drinking water quality of 42 schools in Pingtung County was conducted according to the water sources, treatment facilities, location of school as well as different grade levels. Among them, 45% of schools used tap water as the main source of drinking water, and the schools using groundwater and surface water as drinking water source account for 29% and 26%, respectively. The schools above senior high school level in the city used tap water as drinking water more than underground water, while the schools under junior high school level in the rural area used surface water as their main source of drinking water. The surface water was normally boiled before being provided to their students. The reverse osmosis system is a commonly used water treatment equipment for those schools using tap water or underground water. Drinking fountain or boiled water unit is widely installed in schools above senior high school level. For schools under junior high school level, a pipeline is stretched across the campus. Relative test shows that the unqualified rate of microbe in water is 26.2%. All parameters for physical and chemical properties and metal content had met the domestic standards except that the turbidity of schools under junior high school level using tap water is slightly higher than the standard value.     

Differential survival and reproductive performance across three mitochondrial lineages in Melita plumulosa following naphthalene exposure

Populations subject to anthropogenic contaminants often display altered patterns of genetic variation, including decreased genetic variability. Selective pressures of contaminant exposure are also reflected in differential tolerance between genotypes. An industrial chemical spill in a major eastern Australian waterway in July 2006 resulted in altered patterns of genetic variability in a nearby population of the amphipod, Melita plumulosa for up to one year post-spill, despite the site being declared clean after 48 h. Here, we investigate the toxicant response of three mitochondrial lines naturally occurring at the impacted site by comparing survivorship and life-history trait variables following naphthalene exposure. Overall, M. plumulosa demonstrated differential survivorship between mitochondrial lines under exposure to high concentrations of naphthalene. In addition, we identified differential fecundity and frequencies of gravidity in female amphipods between the mitochondrial haplotypes examined. These findings suggest that the patterns of genetic variability previously identified may be linked with differential tolerance and/or reproductive performance between mitochondrial lineages.     

Effects of the anti-fouling herbicide Irgarol 1051 on two life stages of the grass shrimp,Palaemonetes pugio

This study investigated lethal and sublethal effects (glutathione, lipid peroxidation, cholesterol, and acetylcholinesterase) of the anti-fouling herbicide Irgarol 1051 on larval and adult grass shrimp (Palaemonetes pugio). The 96-hour LC50 test for larvae resulted in an estimated LC50 of 1.52 mg/L (95% confidence interval [CI] 1.26–1.85 mg/L). The adult 96-h LC50 was 2.46 mg/L (95% CI = 2.07–2.93 mg/L). Glutathione, lipid peroxidation, cholesterol and acetylcholinesterase levels were not significantly affected in adult grass shrimp by exposure of up to 3.00 mg/L irgarol. Lipid peroxidation and acetylcholinesterase levels in the larvae were significantly higher than controls in the highest irgarol exposures of 1.0 and 2.0 mg/L, respectively. Cholesterol levels were significantly reduced in larvae in all four irgarol concentrations tested while glutathione levels were not significantly affected in larvae. Both lethal and sublethal effects associated with irgarol exposure were only observed at concentrations well above those reported in the environment.     

Assessment of silver nanoparticle-induced physiological and molecular changes in Arabidopsis thaliana

In this study, the effect of silver nanoparticles and silver ions on Arabidopsis thaliana was investigated at physiological and molecular levels. The seedlings were grown in sublethal concentrations of silver nanoparticles and silver ions (0.2, 0.5, and 1 mg/L) in 1/4 Hoagland’s medium for 14 days under submerged hydroponic conditions. Significantly higher reduction in the total chlorophyll and increase in anthocyanin content were observed after exposure to 0.5 and 1 mg/L silver nanoparticles as compared to similar concentrations of silver ions. Lipid peroxidation increased significantly after exposure to 0.2, 0.5, and 1 mg/L of silver nanoparticles and 0.5 and 1 mg/L of silver ions. Qualitative analysis with dichloro-dihydro-fluorescein diacetate and rhodamine 123 fluorescence showed a dose-dependent increase in reactive oxygen species production and changes in mitochondrial membrane potential in the roots of seedlings exposed to different concentrations of silver nanoparticles. Real-time PCR analysis showed significant upregulation in the expression of sulfur assimilation, glutathione biosynthesis, glutathione S-transferase, and glutathione reductase genes upon exposure to silver nanoparticles as compared with silver ions. Overall, based on the physiological and molecular level responses, it was observed that exposure to silver nanoparticles exerted more toxic response than silver ions in A. thaliana.