Influence of diesel fuel on seed germination

The use of plant-based systems to remediate contaminated soils has become an area of intense scientific study in recent years and it is apparent that plants which grow well in contaminated soils need to be identified and screened for use in phytoremediation technologies. This study investigated the effect of diesel fuel on germination of selected plant species. Germination response varied greatly with plant species and was species specific, as members of the same plant family showed differential sensitivity to diesel fuel contamination. Differences were also seen within plant subspecies. At relatively low levels of diesel fuel contamination, delayed seed emergence and reduced percentage germination was observed for the majority of plant species investigated. Results suggest the volatile fraction of diesel fuel played an influential role in delaying seed emergence and reducing percentage germination. In addition, the remaining diesel fuel in the soil added to this inhibitory effect on germination by physically impeding water and oxygen transfer between the seed and the surrounding soil environment, thus hindering the germination response.     

Cumulative environmental change: Conceptual frameworks,evaluation approaches,and institutional perspectives

Cumulative environmental change or cumulative effects may result from the additive effect of individual actions of the same nature or the interactive effect of multiple actions of a different nature. This article reviews conceptual frameworks of cumulative environmental change and describes analytical and institutional approaches to cumulative effects assessment (CEA). A causal model is a common theoretical construct, although the frameworks vary in their emphasis on different components of the model. Two broad approaches to CEA are distinguished: one scientific and the other planning oriented. These approaches should not be interpreted as competing paradigms but rather different interpretations of the scope of CEA. Each approach can provide a distinct but complementary contribution to the analysis, assessment, and management of cumulative effects. A comparison of the institutional and legislative response to CEA in Canada and the United States shows that Canada is following the American example of incorporating the analysis and assessment of cumulative effects into regulatory actions and administrative procedures that also govern environmental impact assessment.     

Contaminants in Wintering Canvasbacks and Scaups from San Francisco Bay, California

Organochlorines, metals, and trace elements were measured in liver, kidney, or whole-body tissues of canvasbacks (Aythya valisineria), lesser scaups (A. affinis), and greater scaups (A. marila) collected from San Francisco Bay and three coastal areas of California during the winter of 1986–1987. Potentially toxic concentrations of mercury (mean 10.4 µg/g, dry weight) and selenium (mean 32.7 µg/g, dry weight) were found in livers of scaups and canvasbacks from several San Francisco Bay sites. These elements varied spatially, temporally, and between species, with the highest concentrations found in late winter. Mean concentrations of mercury, selenium, and cadmium were generally higher in scaups than in canvasbacks. Of all the organochlorines included in the analyses, only p,p'-DDE and total PCBs were detected in all samples in this study. Mean whole-body concentrations of DDE and PCBs from San Francisco Bay ducks collected in late winter varied spatially and between species, but the concentrations were not considered toxic. Causes for inter-specific differences are unclear, but may be attributable to differences in diet, movement, or physiology.     

Perceiving Land-Degrading Activities from the Lay Perspective in Northern China

Investigation into local peoples’ perceptions can produce useful information that could be incorporated into the decision-making process to help resolve environmental problems. Within the arena of land degradation, a number of studies have also been conducted to explore local peoples’ views of the problem. However, the perceptions of land-degrading practices of the general public have so far not been actively solicited. This study aimed to contribute to this area of research by adopting the psychometric scaling technique to empirically explore the lay public’s ecological risk perceptions of land-degrading activities in Minqin County in Gansu Province, northern China. The primary data were collected via a questionnaire survey (n = 1,138) administered between 14 and 31 December 2002. The major findings of the survey were: (1) Respondents perceived the ecological risks posed by different land-degrading activities to be different. (2) There was a considerable incongruence in the way in which mining of groundwater was conceived by experts and laymen, respectively. (3) Respondents were pretty unsure of expert knowledge. (4) Respondents’ ecological risk perceptions were significantly affected by their personal attributes. As far as the policy implications of these findings are concerned, this study accentuates that we must be aware of, and involved in, the environmental perceptions of the lay public in order to succeed in guiding any human-environment tensions along more sustainable trajectories and navigating the transition to sustainability.     

Coral reef aerosol emissions in response to irradiance stress in the Great Barrier Reef,Australia

We investigate the correlation between stress-related compounds produced by corals of the Great Barrier Reef (GBR) and local atmospheric properties—an issue that goes to the core of the coral ecosystem’s ability to survive climate change. We relate the variability in a satellite decadal time series of fine-mode aerosol optical depth (AOD) to a coral stress metric, formulated as a function of irradiance, water clarity, and tide, at Heron Island in the southern GBR. We found that AOD was correlated with the coral stress metric, and the correlation increased at low wind speeds, when horizontal advection of air masses was low and the production of non-biogenic aerosols was minimal. We posit that coral reefs may be able to protect themselves from irradiance stress during calm weather by affecting the optical properties of the atmosphere and local incident solar radiation.     

Permutation/randomization-based inference for environmental data

Quantitative inference from environmental contaminant data is almost exclusively from within the classic Neyman/Pearson (N/P) hypothesis-testing model, by which the mean serves as the fundamental quantitative measure, but which is constrained by random sampling and the assumption of normality in the data. Permutation/randomization-based inference originally forwarded by R. A. Fisher derives probability directly from the proportion of the occurrences of interest and is not dependent upon the distribution of data or random sampling. Foundationally, the underlying logic and the interpretation of the significance of the two models vary, but inference using either model can often be successfully applied. However, data examples from airborne environmental fungi (mold), asbestos in settled dust, and 1,2,3,4-tetrachlorobenzene (TeCB) in soil demonstrate potentially misleading inference using traditional N/P hypothesis testing based upon means/variance compared to permutation/randomization inference using differences in frequency of detection (Δf _d). Bootstrapping and permutation testing, which are extensions of permutation/randomization, confirm calculated p values via Δf _d and should be utilized to verify the appropriateness of a given data analysis by either model.     

Note On a Slurry Method of Particle Induction

A slurry method of induction of test particles into a high-temperature, high-pressure gaseous flow stream is presented. The method can provide accurate control and sensitive adjustment of the particle feed and can have an ameliorative effect on particle statistics.