The phytotoxic effect of C(1)/C(2)-halocarbons and trichloroacetic acid on the steppe plant Artemisia lerchiana

Artemisia lerchiana is a wormwood species of the Central Asian steppe regions, where it completely cover whole areas. For the first time it was possible to show through field experiments that C(1)/C(2) halocarbons (VCHCs), such as chloroform (CHL), tetrachloroethene (PER) and hexachloroethane (HEX), can be taken up by test plants of the species A. lerchiana via the soil/root pathway and metabolised inter alia into trichloroacetic acid (TCA) under semi-aride conditions. At the same time, chlorophyll a fluorescence measurements carried out on the test plants revealed a phytotoxic influence on plant vitality (max. decline in vitality of 52% with application of CHL) and less efficient energy flows in the photosynthesis mechanism of the A. lerchiana test plants. The authors examine possible links between the simultaneous appearance of VCHCs and additional drought stress in the acceleration of desertification processes.     

Effect of different types of elemental sulfur on bioleaching of heavy metals from contaminated sediments

The application of two different types of elemental sulfur (S0) was studied to evaluate the efficiency on bioleaching of heavy metals from contaminated sediments. Bioleaching tests were performed in suspension and in the solid-bed with a heavy metal contaminated sediment using commercial sulfur powder (technical sulfur) or a microbially produced sulfur waste (biological sulfur) as substrate for the indigenous sulfur-oxidizing bacteria and thus as acid source. Generally, using biological sulfur during suspension leaching yielded in considerably better results than technical sulfur. The equilibrium in acidification, sulfur oxidation and metal solubilization was reached already after 10-14 d of leaching depending upon the amount of sulfur added. The metal removal after 28 d of leaching was higher when biological sulfur was used. The biological sulfur added was oxidized with high rate, and no residual S0 was detectable in the sediment samples after leaching. The observed effects are attributable to the hydrophilic properties of the biologically produced sulfur particles resulting in an increased bioavailability for the Acidithiobacilli. In column experiments only poor effects on the kinetics of the leaching parameters were observed replacing technical sulfur by biological sulfur, and the overall metal removal was almost the same for both types of S0. Therefore, under the conditions of solid-bed leaching the rate of sulfur oxidation and metal solubilization is more strongly affected by transport phenomena than by microbial conversion processes attributed to different physicochemical properties of the sulfur sources. The results indicate that the application of biological sulfur provides a suitable means for improving the efficiency of suspension leaching treatments by shortening the leaching time. Solid-bed leaching treatments may benefit from the reuse of biological sulfur by reducing the costs for material and operating.     

Transient effect of the herbicide flazasulfuron on carbohydrate physiology in Vitis vinifera L

In the Champagne vineyard, most of the areas treated in early 2000 with the newly approved herbicide flazasulfuron had vines with altered growth and yellow leaves throughout the growing season. In order to clarify the physiological perturbations caused on the non-target grapevine and their potential consequences, C nutrition of grape plants grown in vineyards treated or not with flazasulfuron in 2000 was characterized during the following season. Vines from treated areas exhibited yellow leaves and an alteration of photosynthetic activity, characterized by declines in leaf gas exchanges (by 85%) and photosynthetic pigment concentrations (by 88%), and a marked disorganization of the leaf plastids. The herbicide also caused a decrease in leaf starch and soluble carbohydrate levels (-74% and -90%, respectively). Surprisingly, some vines re-greened after bloom, then exhibiting similar carbohydrate physiology to those grown in a non-treated area. Thus, recovery of CO(2) fixation rates, plastid ultra-structure, pigment concentrations and carbohydrate levels was found in re-greening leaves. Unlike the informations available in the literature, our results showed that flazasulfuron may be phytotoxic for grapevine. However, this toxicity was overcome the following year, indicating that vines have the potential to recover from this herbicide stress after one season.     

Structural effect of the in situ generated titania on its ability to oxidize and capture the gas-phase elemental mercury

Structural effect of the in situ generated TiO(2) sorbent particle was examined for its ability to capture elemental mercury under UV irradiation in a simulated combustion flue gas. Titania particles were prepared by thermal gas-phase oxidation of Titanium (IV) isopropoxide (TTIP) using a high temperature electric furnace reactor. The structural characteristics of the in situ generated TiO(2) at various synthesis temperatures were investigated; size distribution and the geometric mean diameter were measured using a scanning mobility particle sizer, while fractal dimension and radius of gyration were evaluated from the transmission electron microscopy images. Results from the Hg(0) capture experiment show that with increasing titania synthesis temperature, the overall aggregate size increases and the morphology becomes more open-structured to gas-phase Hg(0) and UV light, resulting in the improved mercury removal capability.     

Phosphate removal and recovery with a synthetic hydrotalcite as an adsorbent

Phosphate removal is important to control eutrophication and an ion exchange process is one of several treatment processes for this purpose. Hydrotalcite compounds (HTALs) are useful as adsorbents for phosphate removal because of their ion exchange properties. In this study, the adsorption properties of a granular synthetic HTAL for phosphate and the method of regeneration of the granular HTAL were examined. The adsorption isotherm of the granular HTAL was approximated by a modified Langmuir type, and the maximum adsorption capacity was 47.3 mg P g(-1), which corresponded to the content of HTAL in the granular one. Phosphate adsorbed on the HTAL was effectively desorbed with alkaline NaCl solutions and the HTAL was regenerated with 25 w/v% MgCl(2) solution. The regenerated HTAL could be reused repeatedly for the phosphate removal. Phosphate in the exhausted desorption solution was recovered as a precipitate of calcium phosphate by addition of CaCl(2), and the residual exhausted desorption solution could be also reused after supplying NaOH. The results suggest the possibility of an effective system for phosphate removal and recovery, which includes the following processes: adsorption, desorption, recovery of phosphate, and regeneration of the HTAL and the desorption solution.     

Sources of errors in assessing ozone visible symptoms on native vegetation

This paper aims to identify the problems regarding the evaluation of ozone (and ozone-like) symptoms, by examining the results of the 4th UN/ECE ICP-Forests Intercalibration Course for the assessment of ozone-induced visible symptoms. Trees, shrubs and herbaceous species were evaluated in a tree nursery, at Lattecaldo (Switzerland) and under open field conditions at Moggio (Italy). The main findings were: (i) the most expert surveyors tended to be grouped in the same cluster and, during the field exercises, they tended to assess in a more conservative manner compared to the less trained participants; (ii) the agreement was greater in assessing the absence rather than the presence of symptoms; (iii) typical interveinal stippling on the upper leaf surface was more accurately evaluated than discoloration; (iv) uncertainties resulted mainly for species which showed greater variability in their symptom manifestation, and for certain herbaceous species.     

Use of hydra for chronic toxicity assessment of waters intended for human consumption

Methods developed with the cnidarian, Hydra attenuata (Pallas), have proven effective for screening acute toxicity in aqueous samples, whereas their use in revealing (sub)chronic toxic effects have had mitigated success. We therefore sought to explore manifestations of hydra mortality and abnormal morphological changes, as well as the reproductive capacity of hydras to further enhance the bioassay sensitivity and to assess (sub)chronic toxicity. These parameters were recorded following the onset of experiments after 8, 12 and 19-21 days of hydra exposure. Results obtained with potable waters (30 brands of bottled waters and artesian waters from 9 wells) showed chronic sublethal and lethal effects or reproduction rate inhibition for most samples. The effectiveness of the hydra toxicity test was demonstrated in comparison with other widely used bioassays. Our previous and present investigations suggest that hydra is a reliable and relevant test organism for the assessment of acute and chronic water toxicity.     

The Best-of-2-Worlds philosophy: Developing local dismantling and global infrastructure network for sustainable e-waste treatment in emerging economies

E-waste is a complex waste category containing both hazardous and valuable substances. It demands for a cost-efficient treatment system which simultaneously liberates and refines target fractions in an environmentally sound way. In most developing countries there is a lack of systems covering all steps from disposal until final processing due to limited infrastructure and access to technologies and investment. This paper introduces the ‘Best-of-2-Worlds’ philosophy (Bo2W), which provides a network and pragmatic solution for e-waste treatment in emerging economies. It seeks technical and logistic integration of ‘best’ pre-processing in developing countries to manually dismantle e-waste and ‘best’ end-processing to treat hazardous and complex fractions in international state-of-the-art end-processing facilities. A series of dismantling trials was conducted on waste desktop computers, IT equipment, large and small household appliances, in order to compare the environmental and economic performances of the Bo2W philosophy with other conventional recycling scenarios. The assessment showed that the performance of the Bo2W scenario is more eco-efficient than mechanical separation scenarios and other local treatment solutions. For equipment containing substantial hazardous substances, it demands the assistance from domestic legislation for mandatory removal and safe handling of such fractions together with proper financing to cover the costs. Experience from Bo2W pilot projects in China and India highlighted key societal factors influencing successful implementation. These include market size, informal competitors, availability of national e-waste legislation, formal take-back systems, financing and trust between industrial players. The Bo2W philosophy can serve as a pragmatic and environmentally responsible transition before establishment of end-processing facilities in developing countries is made feasible. The executive models of Bo2W should be flexibly differentiated for various countries by adjusting to local conditions related to operational scale, level of centralized operations, dismantling depth, combination with mechanical processing and optimized logistics to international end-processors.