Mercury pollution in a mining area of Guizhou,China: Fluxes over contaminated surfaces and concentrations in air,biological and geological samples

A dynamic flux chamber has been used to estimate fluxes of mercury over different types of surfaces in an abandoned open‐cut mine of Tongren prefecture, Guizhou province, China during spring and summer of 1996. The highest fluxes were obtained over cinnabar slag and contaminated soils, whereas the emissions above cinnabar ore were substantially lower. These fluxes was scaled up to estimate the contribution of mercury emissions to air from mercury wastes, compared to anthropogenic activities in the province of Guizhou, China. Atmospheric mercury concentrations measured were enhanced in the mining area (<1.3 μg m^‐3) compared to regional background sites (1.8–5.1 ng m^‐3). The spreading of mercury was estimated by using biological and geological samples. Moss bags have been employed to estimate long‐time dry‐ and wet‐deposition to this area.     

Advanced solid-state carbon-13 nuclear magnetic resonance spectroscopic studies of sewage sludge organic matter: detection of organic "domains"

Two novel solid-state 13C nuclear magnetic resonance (NMR) spectroscopic techniques, PSRE (proton spin relaxation editing) and RESTORE [Restoration of Spectra via T(CH) and T(1rho)H (T One Rho H) Editing], were used to provide detailed chemical characterization of the organic matter from six Australian sewage sludges. These methods were used to probe the submicrometer heterogeneity of sludge organic matter, and identify and quantify spatially distinct components. Analysis of the T1H relaxation behavior of the sludges indicated that each sludge contained two types of organic domains. Carbon-13 PSRE NMR subspectra were generated to determine the chemical nature of these domains. The rapidly relaxing component of each sludge was rich in protein and alkyl carbon, and was identified as dead bacterial material. The slowly relaxing component of each sludge was rich in carbohydrate and lignin structures, and was identified as partly degraded plant material. The bacterial domains were shown, using the RESTORE technique, to also have characteristically rapid T(1rho)H relaxation rates. This rapid T(1rho)H relaxation was identified as the main cause of underrepresentation of these domains in standard 13C cross polarization (CP) NMR spectra of sludges. The heterogeneous nature of sewage sludge organic matter has implications for land application of sewage sludge, since the two components are likely to have different capacities for sorbing organic and inorganic toxicants present in sewage sludge, and will decompose at different rates.     

Response of Ceriodaphnia dubia to ionic silver: discrepancies among model predictions, measured concentrations and mortality

Silver thiosulfate, often a waste product of photoprocessing, is less bioavailable or toxic to aquatic organisms than is ionic silver. We conducted duplicate 48-h Ceriodaphnia dubia tests in reconstituted laboratory water using treatments of 92.7 nM Ag+ with various concentrations of thiosulfate. Expected Ag+ concentrations were generated for thiosulfate treatment levels using MINEQL + chemical equilibrium modeling. Ag+ concentrations in treatments were determined using a novel silicon-based sensor. Based on predicted Ag+ and published 48-h LC50 values for C. dubia, we did not expect to observe adverse effects. Yet, 100% mortality was observed at low thiosulfate treatments, whereas > 85% and > 95% survival was observed at higher thiosulfate treatment levels, respectively. Our results indicate that biotic responses match the sensor-based Ag+ concentrations. However, there is a discrepancy between these empirical results and responses expected to occur with Ag+ concentrations as predicted by MINEQL + chemical modeling. By correlating silicon sensor data with toxicity results obtained from our laboratory, our work clearly relates a specific chemical form (Ag+) to toxicity results.     

Inside-sediment partitioning of PAH, PCB and organochlorine compounds and inferences on sampling and normalization methods

Comparability of sediment analyses for semivolatile organic substances is still low. Neither screening of the sediments nor organic-carbon based normalization is sufficient to obtain comparable results. We are showing the interdependency of grain-size effects with inside-sediment organic-matter distribution for PAH, PCB and organochlorine compounds. Surface sediment samples collected by Van-Veen grab were sieved and analyzed for 16 PAH, 6 PCB and 18 organochlorine pesticides (OCP) as well as organic-matter content. Since bulk concentrations are influenced by grain-size effects themselves, we used a novel normalization method based on the sum of concentrations in the separate grain-size fractions of the sediments. By calculating relative normalized concentrations, it was possible to clearly show underlying mechanisms throughout a heterogeneous set of samples. Furthermore, we were able to show that, for comparability, screening at <125 μm is best suited and can be further improved by additional organic-carbon normalization.     

Assessment of Integrated Pedestrian Protection Systems with Autonomous Emergency Braking (AEB) and Passive Safety Components

Objective: Autonomous emergency braking (AEB) systems fitted to cars for pedestrians have been predicted to offer substantial benefit. On this basis, consumer rating programs—for example, the European New Car Assessment Programme (Euro NCAP)—are developing rating schemes to encourage fitment of these systems. One of the questions that needs to be answered to do this fully is how the assessment of the speed reduction offered by the AEB is integrated with the current assessment of the passive safety for mitigation of pedestrian injury. Ideally, this should be done on a benefit-related basis.

The objective of this research was to develop a benefit-based methodology for assessment of integrated pedestrian protection systems with AEB and passive safety components. The method should include weighting procedures to ensure that it represents injury patterns from accident data and replicates an independently estimated benefit of AEB.

Methods: A methodology has been developed to calculate the expected societal cost of pedestrian injuries, assuming that all pedestrians in the target population (i.e., pedestrians impacted by the front of a passenger car) are impacted by the car being assessed, taking into account the impact speed reduction offered by the car's AEB (if fitted) and the passive safety protection offered by the car's frontal structure. For rating purposes, the cost for the assessed car is normalized by comparing it to the cost calculated for a reference car.

The speed reductions measured in AEB tests are used to determine the speed at which each pedestrian in the target population will be impacted. Injury probabilities for each impact are then calculated using the results from Euro NCAP pedestrian impactor tests and injury risk curves. These injury probabilities are converted into cost using “harm”-type costs for the body regions tested. These costs are weighted and summed. Weighting factors were determined using accident data from Germany and Great Britain and an independently estimated AEB benefit. German and Great Britain versions of the methodology are available. The methodology was used to assess cars with good, average, and poor Euro NCAP pedestrian ratings, in combination with a current AEB system. The fitment of a hypothetical A-pillar airbag was also investigated.

Results: It was found that the decrease in casualty injury cost achieved by fitting an AEB system was approximately equivalent to that achieved by increasing the passive safety rating from poor to average. Because the assessment was influenced strongly by the level of head protection offered in the scuttle and windscreen area, a hypothetical A-pillar airbag showed high potential to reduce overall casualty cost.

Conclusions: A benefit-based methodology for assessment of integrated pedestrian protection systems with AEB has been developed and tested. It uses input from AEB tests and Euro NCAP passive safety tests to give an integrated assessment of the system performance, which includes consideration of effects such as the change in head impact location caused by the impact speed reduction given by the AEB.     

Climate change,adaptation and Eco-Art in Singapore

Eco-Art has recently emerged as a potential means to place emphasis on environmental issues such as climate change, recycling and the metabolism of the city experienced both materially and conceptually within local, regional and global contexts. Such art presents the possibility of shaping civic practices in arenas beyond those of traditional planning domains. Adopting a pragmatic approach, which recognises the contextual pluralism that exists in debates regarding climate change, this paper is interested in how Eco-Art projects encourage the re-imagining of urban spaces within the context of sustainability, and flows of materials and the recycling of plastic in art specifically.