Food-chain transfer of zinc from contaminated Urtica dioica and Acer pseudoplatanus L. to Microlophium carnosum and Drepanosiphum platanoidis Schrank

This study examines the food-chain transfer of Zn from two plant species, Urtica dioica (stinging nettle) and Acer pseudoplatanus (sycamore maple), into their corresponding aphid species, Microlophium carnosum and Drepanosiphum platanoidis. The plants were grown in a hydroponic system using solutions with increasing concentrations of Zn from 0.02 to 41.9 mg Zn/l. Above-ground tissue concentrations in U. dioica and M. carnosum increased with increasing Zn exposure (p < 0.001). Zn concentrations in A. pseudoplatanus also increased with solution concentration from the control to the 9.8 mg Zn/l solution, above which concentrations remained constant. Zn concentrations in both D. platanoidis and the phloem tissue of A. pseudoplatanus were not affected by the Zn concentration in the watering solution. It appears that A. pseudoplatanus was able to limit Zn transport in the phloem, resulting in constant Zn exposure to the aphids. Zn concentrations in D. platanoidis were around three times those in M. carnosum. Concentrations of Zn in two aphid species are dependant on species and exposure

Reduced bioavailability of Au and isotopically enriched ¹⁰⁹Ag nanoparticles transformed through a pilot wastewater treatment plant in Hyalella azteca under environmentally relevant exposure scenarios

Wastewater Treatment Plants (WWTP) are a major repository and entrance path of nanoparticles (NP) in the environment and hence play a major role in the final NP fate and toxicity. Studies on silver nanoparticles (AgNP) transport via the WWTP system and uptake by aquatic organisms have so far been carried out using unrealistically high AgNP concentrations, unlikely to be encountered in the aquatic environment. The use of high AgNP concentrations is necessitated by both the low sensitivity of the detection methods used and the need to distinguish background Ag from spiked AgNP. In this study, isotopically enriched 109AgNP were synthesized to overcome these shortcomings and characterized by a broad range of methods including transmission electron microscopy, dynamic and electrophoretic light scattering. 109AgNP and gold NP (AuNP) were spiked to a pilot wastewater treatment plant fed with municipal wastewater for up to 21 days. AuNP were used as chemically less reactive tracer. The uptake of the pristine and transformed NP present in the effluent was assessed using the benthic amphipod Hyalella azteca in fresh- and brackish water exposures at environmentally relevant concentrations of 30 to 500 ng Au/L and 39 to 260 ng Ag/L. The unique isotopic signature of the 109AgNP allowed to detect the material at environmentally relevant concentrations in the presence of a much higher natural Ag background. The results show that the transformations reduce the NP uptake at environmentally relevant exposure concentrations. For 109Ag, lower accumulation factors (AF) were obtained after exposure to transformed NP (250–350) compared to the AF values obtained for pristine 109AgNP (750–840). The reduced AF values observed for H. azteca exposed to effluent from the AuNP-spiked WWTP indicate that biological transformation processes (e.g. eco-corona formation) seem to be involved in addition to chemical transformation.publishedVersio

Hybrid Vehicle Turbine Engine Technology Support (HVTE-TS) Program 1997–98 Progress

The purpose of this program has been the development of advanced gas turbine engine technologies in support of U.S. Department of Energy (DoE) programs for use in generator sets for hybrid-electric automotive propulsion systems. Initially the objective of this program had been the development of four key technologies to be applied 10 advanced turbogenerators: • structural ceramic materials and processes • low emissions combustion systems • regenerator and seal systems • insulation systems and processes. Of these four, the lack of full program funding has limited 1997 activities to two technologies, i.e.: continued development of ceramics applications and continued regenerator and seal system development. In late 1997, DoE Office of Transportation Technologies discontinued active sponsorship of this effort, and therefore, the potential application to automotive systems now appears to be delayed. However, the application to stationary engines is very relevant and will proceed.</jats:p

Time-efficient approach for environmental transformation and bioavailability assessment of isotopically enriched nanoparticles to increase environmental relevance

The increasing use of engineered nanoparticles (NPs) and their release into the environment requires an assessment of their fate and (eco-) toxicological effects. Previous studies have often focused on pristine NPs or NPs spiked into the effluent of simulated wastewater treatment plants (WWTP) fed with artificial wastewater, combined with unrealistic high exposure concentrations to overcome problems associated with high metal background concentrations. In this study environmentally transformed NPs were obtained by direct spiking into an anaerobic digester filled with municipal sewage sludge. Isotopically enriched 46TiO2 and 68ZnONPs were synthesized and used in the study to allow tracing of their fate in WWTP matrices at environmentally relevant concentrations, despite the high Zn and Ti background levels. NP-spiked sludge was used to create exposure media for uptake studies with the benthic amphipod Hyalella azteca under freshwater and brackish conditions. The results show that while 68ZnONPs nearly achieved the target concentration (90 versus 100 mg 68Zn/kg) in the spiked sludge, the 46TiO2NPs reached only 33 % of the target concentration (100 mg 46Ti /kg), despite the good homogeneity of the 46Ti distribution in the spiked sludge. The latter discrepancy most likely reflects aggregation and subsequent sedimentation of the 46TiO2NPs in the digester unit. Exposure of H. azteca to transformed 68ZnONPs at concentrations between 3.5 and 9.7 μg 68Zn/L led to significant 68Zn accumulation in tissues. Our results show that the transformation processes led to an up to 12 times reduced uptake of 68Zn from the transformed as compared to the pristine 68ZnONPs, and this effect was more pronounced at freshwater exposure conditions. The new method of spiking an anaerobic sludge digestion unit balances environmental relevance, costs, time-efficiency and NPs losses (compared to spiking complete WWTP pilot systems or laboratory models) but requires optimization for NPs prone to aggregation such as TiO2NPs