Fate and effects of silver nanoparticles at the aquatic-terrestrial interface: A floodplain mesocosm experiment

The production volume of engineered inorganic nanoparticles (EINP) successively increased over the last years. Once released into the natural environment, these particles may change their size and surface properties in interaction with other substances. This is expected to control their mobility and their impact on biochemical processes. However, the underlying processes are not fully understood yet. Transformation processes and long-term fate of citrate-coated silver nanoparticles (Ag NP) were investigated in an innovative floodplain mesocosm, which was run with river Rhine water and natural soil from an adjacent floodplain for 33 weeks. Flooding events were simulated every three weeks. The Ag NP with a concentration of 5 mg L-1 were continuously introduced into the water for three weeks followed by a three-week period without spiking. Every third week the ecotoxicological impact of Ag NP was determined by means of Gammarus mortality and feeding assays. At the end of the experiment, the total Ag concentrations were measured in profiles of the floodplain soil and the sediment as well as in algae that developed in the mesocosm. The total Ag concentration in the aquatic phase in the main zone as well as in the floodplain fluctuated according to the periodic Ag NP pulse. Further, significant amounts of Ag accumulated in algae (up to 4.7 mg g-1) and exposed leaves (up to 170 μg g-1). However, for the applied experimental conditions we did neither observed mortality nor sublethal effects on Gammarus feeding activity. More than 40 % of the Ag remained in the sediment of the main zone and 7 % were transported during flooding into the floodplain soil. Furthermore, 0.5 % of the Ag was still in the water phase. Most of the particles were immobilized in the top layer of the sediments and soil. Only very little transport in deeper soil layers was observed in the soil columns and sediment. Accumulation in algae, sediment, and soil is alarming for long-term environmental impact assessments and the long lifetime in the aqueous phase suggests long-range transport of Ag NP in rivers

Behavior of thermally modified wood to biodeterioration by xylophage fungi.

Thermally modified wood undergoes chemical, physical, and mechanical modifications, resulting in changes in resistance to wood biodegrading agents. The objective of this study was to evaluate the resistance to biodeterioration of thermally modified wood by the industrial process VAP HolzSysteme® of Eucalyptus grandis, Pinus taeda and Tectona grandis, submitted to the Lentinula edodes fungi (brown rot) and Pleurotus djamor fungi (white rot), and to analyze the chemical properties, contents of holocellulose, lignin, total extracts, and ash, before and after biodeterioration. Three treatments were considered for each species: Control - wood in natura, modified wood at 140 °C and 160 °C. The specimens were made according to ASTM D 1413 (ASTM, 1994), in a total of 108 samples per species, 36 per treatment for each species, with 12 samples submitted to the fungus L. edodes, 12 to P. djamor and 12 correction blocks. Different behaviors occurred among species under fungal action. For E. grandis wood the thermal modification increased the resistance to biodeterioration of the wood under the action of the L. edodes fungus, in the opposite way occurred for the species P. taeda. There was little variation between treatments in T. grandis wood for both fungi. Thermal modification conferred chemical alterations on the wood, influencing their behavior the biodeterioration by the fungal action in P. taeda species in a negative way, (increasing the degradation level), and E. grandis in a positive way, reducing the biodeterioration. However, in T. grandis species no significant differences were identified in the different treatments by the action of different rotting fungi

Bioterrorism: What Should Hotels Do to Reduce the Risk?

Since September 11, 2001, the United States recognizes the global risk of terrorism. Although the risk of a terrorist attack at any one hotel is very low, the severity of the consequences is great, making it important for hoteliers to understand terrorist motives and to protect hotel guests and assets to the fullest extent possible. Terrorists desire to cause fear and social disruption and to use violence to make their message known to a global audience. Most terrorist attacks currently involve explosives, but biological weapons have the potential to harm much larger populations, especially if released into the air, building ventilation systems, or water supplies. Hotels that serve international customers, hold an iconic brand, or are owned by persons considered to be part of an “enemy” group are most at risk. No bioterrorism mitigation guidelines specific to hotels have yet been developed with input from hotel security managers. Guidelines are needed to establish best practices and security benchmarks, and to develop training programs for managers and employees. This study uses a Delphi method to poll hotel security managers about critical and feasible measures that hotels should take to prevent acts of bioterrorism. This information can be used to prioritize strategies for bioterrorism prevention and response, and can be utilized as the basis for establishing industry best practices and benchmarks. It is one of the first studies to investigate guidelines for bioterrorism in the hotel industry. As such this study can be used as a foundation for future research