Manganese and trace-metal mobility under reducing conditions following in situ oxidation of TCE by KMnO4: a laboratory column experiment

The stability of Mn oxides, and the potential for mobilization of associated trace metals, were assessed by simulating the onset of microbially-mediated reducing conditions in a continuous-flow column experiment. The column had previously been used for an in situ chemical oxidation (ISCO) experiment in which trichloroethylene was reacted with permanganate in the presence of aqueous trace metals, which produced Mn oxyhydroxides (MnO(x)) that sequestered the trace metals and coated the column sand. The column influent solution represented the incursion of ambient groundwater containing dissolved organic carbon (DOC) into an ISCO treatment zone. The influx of DOC-containing groundwater initiated a series of cation-exchange, surface-complexation and reductive-dissolution reactions that controlled the release of aqueous metals from the system. Peak concentrations in the effluent occurred in the order Na, Mo, Cr, Zn, K, Mn, Fe, Pb, Mg, Ni, Cu and Ca. Manganese release from the column was controlled by a combination of cation exchange, reductive dissolution and precipitation of rhodochrosite. The trend in Fe concentrations was similar to that of Mn, and also resulted from a combination of reductive dissolution and cation exchange. Cation exchange and/or surface-complexation were the primary mechanisms controlling Cu, Ni, Mo and Pb release to solution, while Zn and Cr concentrations did not display coherent trends. Although metal release from the treatment zone was evident in the data, concentrations of trace metals remained below 0.05 mg L(-1) with the exception of Mo which reached concentrations on the order of 1 mg L(-1). The establishment of anaerobic conditions in ISCO-treated aquifers may result in a prolonged flux of aqueous Mn(II), but with the exception of MoO(4)(2-), it is unlikely that trace metals sequestered with MnO(x) during ISCO will be released to the groundwater in elevated concentrations.     

Effects of urbanization on the population structure of freshwater turtles across the United States

Landscape‐scale alterations that accompany urbanization may negatively affect the population structure of wildlife species such as freshwater turtles. Changes to nesting sites and higher mortality rates due to vehicular collisions and increased predator populations may particularly affect immature turtles and mature female turtles. We hypothesized that the proportions of adult female and immature turtles in a population will negatively correlate with landscape urbanization. As a collaborative effort of the Ecological Research as Education Network (EREN), we sampled freshwater turtle populations in 11 states across the central and eastern United States. Contrary to expectations, we found a significant positive relationship between proportions of mature female painted turtles (Chrysemys picta) and urbanization. We did not detect a relationship between urbanization and proportions of immature turtles. Urbanization may alter the thermal environment of nesting sites such that more females are produced as urbanization increases. Our approach of creating a collaborative network of scientists and students at undergraduate institutions proved valuable in terms of testing our hypothesis over a large spatial scale while also allowing students to gain hands‐on experience in conservation science.     

Communicating uncertainty via probabilities: The case of weather forecasts

Capturing uncertainty through numerical probabilistic statements is orthodoxy in risk science—and most of science and technology. There are a wide range of views on the utility of such statements for risk communication, and they are often seen as being central to the failure to generate common understanding about risks between science and non-scientists. The extent to which probability statements are understood is unclear. If such statements are misunderstood by many, what alternatives might communicate uncertainty better?

These questions are examined in the context of daily weather forecasts. The probabilities used in such statements concern daily events experienced by everyone, unlike the extremely small probabilities about unfamiliar events often used in risk communication. If people do not understand weather forecasts, there is little hope that statements about unfamiliar events using unfamiliar language will be understood. Some jurisdictions use numerical probabilistic statements on the likelihood of precipitation, and a variety of qualitative or categorical forecasts are also used. Drawing on a range of sources including public surveys conducted by the Australian Bureau of Meteorology, the paper examines public understanding of probabilities and public and specialist understanding of verbal categorical forecast terms.

The majority of those surveyed have basic understanding about probabilities as used in weather forecasts, but significant groups do not. However, there was limited agreement among forecasters on what the probabilistic statements meant. Similarly, there was limited shared meaning between forecasters and the public on the verbal forecast expression examined.     

Environmental cadmium levels increase phytochelatin and glutathione in lettuce grown in a chelator-buffered nutrient solution

Phytochelatins are enzymatically synthesized peptides involved in metal detoxification and have been measured in plants grown at very high Cd concentrations, but few studies have examined the response of plants at lower environmentally relevant Cd concentrations. Using an ethylenediaminetetraacetic acid (EDTA)-buffered nutrient medium, we have varied Cd exposure and measured phytochelatin and glutathione concentrations in romaine lettuce (Lactuca sativa L. var. longifolia Lam. var. Parris Island) grown in a flow-through hydroponic (FTH) system. Very low free ionic Cd (10(-9.6) M) increased average phytochelatin concentrations above those of controls, and increasing Cd resulted in increased phytochelatin production, though increases were tissue dependent. Glutathione concentrations also increased with increasing Cd. In other standard hydroponic experiments, the media were manipulated to vary total Cd concentration while the ionic Cd was fixed. We found that the total amount of Cd (primarily EDTA bound) in the medium altered thiol production in roots, whereas thiols in leaves remained constant. The Cd uptake into roots and translocation to old leaves was also influenced by the total concentration in the medium. Cadmium in all tissues was lower and in some tissues thiol concentrations were higher than in FTH-grown plants grown in identical medium, suggesting that nutrient delivery technique is also an important variable. Though phytochelatin and glutathione production can be sensitive to changes in bioavailable Cd, thiol concentrations will not necessarily reflect the Cd content of the plant tissues.     

Increasing industrial safety practices and conditions through posted feedback

This study examined the effects of posted feedback for improving safety in a paper mill. Data were taken once a week on 24 practices and 7 conditions. In addition, data on injuries with and without lost time were collected monthly. After posting feedback on safe and unsafe conditions for 6 months, more than half of the 17 divisions of the mill showed improvement. Similarly, safe practices increased after feedback was provided for them for 2 months. Most importantly, injuries were cut in half.     

Evaluation of the effectiveness of traffic calming measures on vehicle speeds and pedestrian injury severity in Ghana

Objectives: Each year, pedestrian injuries constitute over 40% of all road casualty deaths and up to 60% of all urban road casualty deaths in Ghana. This is as a result of the overwhelming dependence on walking as a mode of transport in an environment where there are high vehicular speeds and inadequate pedestrian facilities. The objectives of this research were to establish the (1) impact of traffic calming measures on vehicle speeds and (2) association between traffic calming measures and pedestrian injury severity in built-up areas in Ghana.

Method: Vehicle speeds were unobtrusively measured in 38 selected settlements, including 19 with traffic calming schemes and 19 without. The study design used in this research was a matched case–control. A regression analysis compared case and control casualties using a conditional logistic regression.

Results: Generally, the mean vehicle speeds and the proportion of vehicles exceeding the 50?km/h speed limit were significantly lower in settlements that have traffic calming measures compared to towns without any traffic calming measures. Additionally, the proportion of motorists who exceeded the speed limit was 30% or less in settlements that have traffic calming devices and the proportion who exceeded the speed limit was 60% or more in towns without any traffic calming measures. The odds of pedestrian fatality was significantly higher in settlements that have no traffic calming devices compared to those that have (odds ratio [OR]?=?1.98; 95% confidence interval, 1.09–4.43). The protective effects of a traffic calming scheme that has a speed table was notably higher than those where there were no speed tables.

Conclusion: It was clearly evident that traffic calming devices reduce vehicular speeds and, thus, the incidence and severity of pedestrian injuries in built-up areas in Ghana. However, the fact that they are deployed on arterial roads is increasingly becoming a road safety concern. Given the emerging safety challenges associated with speed calming measures, we recommend that their use be restricted to residential streets but not on arterial roads. Long-term solutions for improving pedestrian safety proposed herein include bypassing settlements along the highways to reduce pedestrians’ exposure to traffic collisions and adopting a modern way of enforcement such as evidence-based laser monitoring in conjunction with a punishment regime that utilizes the demerit points system.     

Agro-predation: usurpation of attine fungus gardens by Megalomyrmex ants

 A new ant species of Megalomyrmex conducts mass raids to usurp gardens of the fungus-growing ant Cyphomyrmex longiscapus, then lives in the gardens and consumes the cultivated fungus. Unlike attine ants, however, Megalomyrmex sp. does not forage for substrate to manure the gardens; therefore, when gardens become depleted, Megalomyrmex sp. must locate and usurp new gardens. Megalomyrmex sp. workers feed their larvae with attine brood, but only after removing the fungal mycelium that covers the attine larval integument, suggesting that this fungal coat may provide partial protection against other predators. Unlike other known Megalomyrmex species, which coexist as social parasites in attine colonies, Megalomyrmex sp. expels its attine hosts during the garden raids. Megalomyrmex sp. thus maintains a unique agro-predatory lifestyle that is described here for the first time. Received: 18 August 2000 / Accepted in revised form: 1 November 2000     

Revised estimates and projections of down syndrome births in the United States,and the effects of prenatal diagnosis utilization, 1970–2002

The objectives of this study were to: (1) calculate revised estimates and projections of United States annual Down syndrome (DS) births for 1970–2002, and (2) estimate the effects of amniocentesis on these baseline DS birth projections. Three models of amniocentesis utilization among 30–34 and ≧ 35-year-old women were considered. The recently revised Census Bureau birth projections, and new single year maternal age DS risk rates estimated from a 1970–1983 Ohio data set, were used. Data from all three Census Bureau projection series were analysed; series II was considered in depth since it is consistent with recent fertility levels. Assuming no use of amniocentesis, total estimated DS births dropped from about 4770 in 1970 to 4120 in 1980 (a 14 per cent decline), but are projected to a plateau of about 5100 by the year 1990 (a 24 per cent increase). DS births to women ≧ 35 would increase dramatically from about 1050 in 1980 to 1900 in 2000 (an 81 per cent increase). Assuming 1983 Ohio prenatal diagnosis ratios for women aged 30–34 (1.7 per cent) and ≧ 35 (23.4 per cent) are used nationally, an annual reduction of about 7 per cent of DS births in 1986 and 9 per cent in 2002 would result. Fifty and 70 per cent utilization among women 30–34 and 235, respectively, would reduce DS births by about 33 per cent in 1986 and 38 per cent in 2002. Therefore, if the projected increase in DS births is to be averted, utilization of prenatal diagnosis by ≧ 30-year-old women must increase substantially.