Covers of the nuclear waste repository are of great significance to the long-term safe storage and disposal of nuclear wastes. Capillary barriers have proven to be effective to resist the downward water seeping into the underlying nuclear wastes, especially in dry climate, and have been widely used worldwide. Infiltrating water is removed from the fine layer by evaporation or transpiration or through percolation into the coarse layer, which plays a critical role in preventing the water from further infiltration in the bulk wastes. In this paper, laboratory infiltration tests were conducted with an organic glass box, filled with fine-grained quartz sand in which a layer of coarse-grained quartz sand was emplaced horizontally or at various slopes (10° and 20°), and the capillary barrier effect under various conditions (different thickness, slop of coarse-grained quartz sand layer, and sprinkling intensity) was investigated in detail. The results show that the thickness of the underlying coarse layer plays a critical role in governing the performance of the capillary barrier. The efficiency of capillary barrier increases with increasing thickness and/or slope of the coarse layer, but decreases with increasing sprinkling intensity. For a sprinkling intensity of 20 mm/day, a 30-mm-thick coarse layer even emplaced horizontally can achieve 100% water diversion. In addition, a visible tracer test was performed with an inert red dyestuff to trace the streamlines; the results indicate that even with a 7-mm-thick coarse layer, the capillary barrier can offer marked ability to prevent water from percolating into the coarse layer. The findings could be useful for improving engineered uses of capillary barriers at waste repository sites.

Although the climate change effects on plants have been a focus for more than two decades, such effects on aquatic species remain largely unknown. To evaluate the potential effects of elevated CO₂ on growth and nutrient uptake of Eichhornia crassipe Solms (commonly known as water hyacinth, the world's most significant invasive aquatic weed), plants were grown at two CO₂ concentrations (380 and 800 ppm) combined with four nutrient levels (oligo-, meso-, eu-, and hypertrophic) for 2 months. Overall, elevated CO₂ consistently enhanced plant growth at all nutrient levels, indicating more infestations of water hyacinth in future natural eutrophic waters. Moreover, the enhancement extent varied among nutrient availabilities, being more in eu- and hypertrophic levels and less in meso- and oligotrophic levels. Furthermore, the CO₂ enrichment-deduced assimilation was allocated more to plant roots than shoots which would improve the nutrient absorption capacity and mostly transferred to offspring ramets rather than maintained at the mother ramet which would benefit the vegetative reproduction. Finally, under elevated CO₂, although the nitrogen (N) and phosphorus (P) contents of E. crassipe slightly decreased which might mean increased difficulties in preventing its infestation by reducing N and/or P in eutrophic waters, the total N and P accumulation increased suggesting higher bioremediation efficiency of using water hyacinth for water eutrophication.

The concentration of Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Se, V and Zn was measured in the aquatic bryophyte Rhynchostegium riparioides after a 4-week transplantation at 83 stations in seven main watercourses and three smaller tributaries of the basin of the River Bacchiglione (NE Italy). The study, carried out in 9 months, aimed at establishing a database for statistical analyses to define a novel index of water quality, specifically calibrated for moss bags, and suitable for bio-monitoring purposes where autochthonous bryophytes are not available. The background level was estimated for each element, the ratio between sample and background concentration was adopted as measure of environmental alteration and a five-class interpretation scale was defined. The 73.8% of measured concentrations reflected a condition of naturality, 16.6% suspect of alteration, 7.6% sure alteration, 1.6% severe alteration and <0.5% extreme alteration. The condition of global environmental alteration (all contaminants) at each station was also defined. Forty-four stations presented absence or suspect of alteration, 39 sure alteration for one or more elements. Bivariate and multivariate analyses revealed (1) highly significant correlations (p < 0.001) between the concentrations of Co-Mn, Sb-Zn, and Fe-V, depending on both natural and human factors, (2) chemical patterns leading to galvanic industries, metallurgy or urban sewages, in some case with a geographical distribution and (3) a gradient of environmental alteration from the Pre-Alps to the lowland. Coloured maps indicate both point sources and widespread environmental alteration, highlighting not only industrial-urban areas but also some apparently undisturbed sites.

A pot experiment was conducted to study the effects of high concentrations of available Cu and Pb in soil originated from the vicinity of a copper foundry in Poland (Cu, 2,585–3,725 mg kg−1 d.wt.; Pb, 1,459–1,812 mg kg−1 d.wt.) on the growth and chemical constituents of Betula pendula seedlings. Control plants grew in unpolluted forest soil. Dry matter accumulation in the plants during the growing season and root/leaf mineral content were determined. Colonization of birch roots by ectomycorrhizal (ECM) fungi also was evaluated, as was soil dehydrogenase activity for influence of the metals on soil microorganisms. The heavy metals negatively affected seedling growth, ECM colonization, and soil dehydrogenase activity. A reverse relationship was found between ECM abundance and heavy metal concentrations in birch leaves, indicating the potential of mycorrhizas to protect the aboveground part of young silver birch seedlings from elevated environmental levels of Cu and Pb.

The photodegradation of azo dyes aqueous solution has been investigated using TiO₂ as catalyst in sunlight. The effect of amount of catalyst, concentration of dye, and pH value on the degradation of Direct Blue 78 was observed. A complete degradation of 100 mg/L Direct Blue 78 solution under solar irradiation was achieved in 6 h at pH 3.0, dosage of TiO₂ 1.0 g/L. A possible pathway for the photodegradation of Direct Blue 78 in sunlight was proposed.

Ballast seawater is considered globally as a major vector for invasions of non-indigenous organisms. Several technologies have been tested for their ability to remove organisms from ballast water. In the present study, we constructed a novel pulsed high-voltage discharge (PHVD) system that could operate in either high current mode with several hundred amperes or shockwave generating mode with relatively lower current in seawater. In laboratory-scale experiments, the PHVD system with shockwave-generating mode was found to be more effective in killing zooplankton (1.9- to 4.0-fold) and phytoplankton (3.3-fold) than high current mode at discharge with 300-500 pulses at 7.1 kV. Further experiments were carried out at different voltages and pulse-numbers to examine effects of the shockwave-generating PHVD system on viabilities of one zooplankton larva, two phytoplankton species, and an indicator bacterium suspended in seawater in a static chamber. For zooplankton, live cells were not detected at discharge with 400 pulses at 13 kV. For phytoplankton, the initial live cells of a dinoflagellate was decreased by 77 ± 0.5%, and the initial chl a concentration of a diatom was decreased by 76 ± 6% at discharge with 700 pulses at 13 kV. For an indicator bacterium Escherichia coli, live cells were not detected at discharges with 200 or 700 pulses at 13 kV. Measurements of ATP content of organisms showed congruent results with those obtained by the above methods, suggesting it may be a rapid method for evaluating treatment efficiency. Though further scale-up studies are necessary, these results suggest that the PHVD system have a high potential for applying to ballast seawater treatment.

Fly ash generated from medical waste incinerator and wastewater produced from electroplating plants contains various hazardous contaminants such as heavy metals and chlorinated organic compounds. The primary goal of this research was to investigate the feasibility of removing heavy metals from wastewater using medical waste incinerator fly ash as the treatment reagent with addition of small amount of sodium carbonate (Na₂CO₃) in a hydrothermal process. Copper (Cu) was used as the model heavy metal contaminant in the process. The results revealed that medical waste incinerator fly ash could effectively stabilize Cu(II) ion from wastewater, the crystal phase and simple substance formed during the treatment played a significant role in the fixation of heavy metals in wastewater and fly ash. The heavy metal leachability of treated ash was also measured after removal process. The co-disposal of Cu-containing wastewater and heavy metals-bearing medical waste incinerator fly ash by hydrothermal treatment with addition of a small amount of Na₂SO₃ was found promising as an effective way of removing Cu from wastewater. The reutilization feasibility of fly ash and the formation mechanism of copper-containing substances were also discussed in this paper.

The performances of a new and a mature integrated constructed wetland (ICW) system treating domestic wastewater were evaluated for the first time. The new ICW in Glaslough (near Monaghan, Ireland) comprises five wetland cells, and the mature system in Dunhill (near Waterford, Ireland) comprises four cells. The performance assessment for these systems is based on physical and chemical parameters collected for 1 year in Glaslough and 5 years in Dunhill. The removal efficiencies for the former system were relatively good if compared to the international literature: biochemical oxygen demand (BOD, 99.4%), chemical oxygen demand (COD, 97.0%), suspended solids (SS, 99.5%), ammonia nitrogen (99.0%), nitrate nitrogen (93.5%), and molybdate-reactive phosphorus (MRP, 99.2%). However, the mature ICW had removal efficiencies that decreased over time as the Dunhill village expanded rapidly. The mean removal efficiencies were as follows: BOD (95.2%), COD (89.1%), SS (97.2%), ammonia nitrogen (58.2%), nitrate nitrogen (−11.8%), and MRP (34.0%). The findings indicate that ICW are efficient in removing BOD, COD, SS, and ammonia nitrogen from domestic wastewater. Moreover, both ICW systems did not pollute the receiving surface waters and the groundwater.

In this report, the toxic effect of TCE (trichloroethylene), PCE (tetrachloroethylene), and potassium dichromate on P. subcapitata was investigated. The test was conducted at different concentrations of pollutants, starting from the European Community limit values defined for each analysed contaminant. Mixtures of pollutants were also tested to verify the combined effect of algae cells. Results suggest that both TCE and PCE were able to reduce P. subcapitata growth and metabolism starting from 0.05 and 0.02 mg L⁻¹ of contaminant, respectively. PCE seems to be substantially more toxic than TCE. Chromium produces a clear effect on algae growth and esterase activity only starting from 1 mg L⁻¹ of potassium dichromate; this result confirms the suitability of EU limit value. AFLP analysis showed that all tested pollutants produce DNA mutations probably due to oxygen radicals. Generally, chromium, at high concentrations, is more toxic and genotoxic that TCE or PCE. Test performed with a mixture of pollutants showed a synergic effect of chromium and organic compounds suggesting that the membrane damage induced from organic substances should increase the chromium cellular access.