Multicomponent simulation of wastewater-derived nitrogen and carbon in shallow unconfined aquifers. II. Model application to a field site

A multicomponent reactive transport model as presented by MacQuarrie and Sudicky [MacQuarrie, K.T.B., Sudicky, E.A., this volume. Multicomponent simulation of wastewater-derived nitrogen and carbon in shallow unconfined aquifers: I. Model formulation and performance, J. Contam. Hydrol.] is applied to a well-studied wastewater plume in a sandy aquifer near Cambridge, Ontario. Domestic wastewater is released into the unsaturated zone via a drain field at a depth of about 0.8 m. The physical transport parameters for the model are obtained by simulating a non-reactive solute, while kinetic input data for the nitrogen and carbon reaction network are obtained from the literature. The model shows that the wastewater-loading rate has little influence on the moisture content in the unsaturated zone, thus oxygen diffusion in the air phase is an important transport mechanism. The model results are in general agreement with the field-determined moisture and oxygen profiles near the drain field. The simulation results show that oxidation of ammonium and dissolved organic carbon (DOC) goes to completion in the 1.5-m distance between the drain field and the water table, and that calcite dissolution limits the pH reduction to about 0.2 units. The model-predicted nitrate concentrations in the core of the plume are in the range of 20-25 mg N/l and are in good agreement with the field data. Overall, the results for the major reactive species from the model simulation agree well with the geochemical data obtained below the drain field and it is concluded that the major physical and biochemical processes have been correctly captured in the current model formulation.     

Hard core drinking drivers

The term "hard core" has been used extensively over the past 15 years to identify persons who drink and drive regularly, typically at high blood alcohol levels. This article discusses how the term arose and clarifies what it means, both as a concept and in practice. It describes the characteristics of hard core drinking drivers and estimates their contribution to drinking driver trips, arrests, and crashes. It summarizes current knowledge and recommendations on the most effective means to affect their behavior and reduce their drinking and driving.     

National-scale vegetation change across Britain; an analysis of sample-based surveillance data from the Countryside Surveys of 1990 and 1998

Patterns of vegetation across Great Britain (GB) between 1990 and 1998 were quantified based on an analysis of plant species data from a total of 9596 fixed plots. Plots were established on a stratified random basis within 501 1 km sample squares located as part of the Countryside Survey of GB. Results are primarily conveyed in terms of a classification of national land-cover into 22 mutually exclusive Broad Habitat types. Each of the fixed vegetation plots could be assigned to the Broad Habitat in which they were located in either year. Two types of analysis are reported, both based on changes in plant species composition within monitoring plots. The first examined turnover and net change between Broad Habitat types. The second quantified more subtle changes that had occurred within each Broad Habitat using a series of condition measures that summarized multivariate plant species data as a single scalar value for each plot at each time. There are major difficulties in using uncontrolled, large-scale surveillance data to unravel causal linkages and no attempt was made to quantitatively partition variation among competing causes. However, it was clear that results were broadly consistent with environmental drivers known to have operated prior to and during the survey interval. Large-scale vegetation changes could be summarized in terms of shifts along gradients of substrate fertility and disturbance. Changes implied increased nutrient availability across upland and lowland ecosystems while, in lowland landscapes, linear features and small biotope fragments saw a marked shift to species compositions associated with greater shade and less disturbance.     

Applying local knowledge: the contribution of oral history to wetland rehabilitation at Kanyapella Basin, Australia

Local knowledge of the history and ecology of wetland ecosystems can be a valuable resource in wetland rehabilitation projects. This is especially the case when other historical ecological information is unavailable. As well as providing a source of historical information, time spent acquiring local knowledge can enhance public participation in environmental management and facilitate early conflict resolution between stakeholders and the community. This paper investigates the use of oral history as a tool to collate a history of the flooding, ecology and management of Kanyapella Basin, a 2581 ha wetland on the floodplain of the Murray and Goulburn Rivers, Australia. Interviews were held with nine local residents and 11 natural resource managers. Oral history proved an effective way to obtain information about changes in the frequency and distribution of flood events over the last 60 years. Observations of rare and threatened fauna, and comments regarding the success of past management were also recorded. Results from the oral history have been used to direct ecological research and develop alternative management options at Kanyapella Basin. In addition to its use in gathering ecological information, oral history also proved effective in enabling the values and concerns of local community and stakeholders to be articulated, increasing managers' understanding of the social context of the particular locality, which is fundamental to sound environmental decision-making.     

Great Lakes management: Ecological factors

Although attempts to improve the quality of the Great Lakes generally focus on chemical pollution, other factors are important and should be considered Ecological factors, such as invasion of the lakes by foreign species, habitat changes, overfishing, and random variations in organism populations, are especially influential. Lack of appreciation of the significance of ecological factors stems partly from the inappropriate application of the concept of eutrophication to the Great Lakes. Emphasis on ecological factors is not intended to diminish the seriousness of pollution, but rather to point out that more cost-effective management, as well as more realistic expectations of management efforts by the public, should result from an ecosystem management approach in which ecological factors are carefully considered.     

Male tail streamer length predicts fertilization success in the North American barn swallow (Hirundo rustica erythrogaster)

In socially monogamous species, extra-pair paternity has the potential to increase the variance in male reproductive success, thereby affecting the opportunity for sexual selection on male extravagant ornamentation. In the European barn swallow (Hirundo rustica rustica), the tail streamer length is a sexually selected male ornament and an honest indicator of viability. The North American barn swallow (Hirundo rustica erythrogaster) also shows sexual dimorphism in tail streamer length, but whether this trait holds the same signalling function in this subspecies is a controversial issue, and the available literature is presently scarce. Here, we present data on paternity in the North American barn swallow, including a complete sampling of extra-pair sires in four colonies. We analysed how extra-pair paternity affected the variance in male fertilization success and examined whether male tail streamer (i.e. the outermost tail feather) length correlated with fertilization success (n=86 males). Extra-pair paternity constituted 31% of all offspring and significantly increased the variance in male fertilization success. The number of offspring sired by extra-pair males accounted for almost half of the total variance in male fertilization success. Males with naturally long tail streamers had a higher fertilization success than males with shorter tail streamers, and this pattern was mainly caused by a higher extra-pair success for males with long tail streamers. Males with long tail streamers also paired with early breeding females in prime body condition. These results are consistent with the idea that there is directional sexual selection on male tail streamer length, possibly mediated through male extra-pair mating success or the timing of breeding onset.     

Phylogeography of two Atlantic squirrelfishes (Family Holocentridae): exploring links between pelagic larval duration and population connectivity

Genetic surveys of reef fishes have revealed high population connectivity within ocean basins, consistent with the assumption that pelagic larvae disperse long distances by oceanic currents. However, several recent studies have demonstrated that larval retention and self-recruitment may be higher than previously expected. To assess connectivity in tropical reef fishes, we contribute range-wide mtDNA surveys of two Atlantic squirrelfishes (family Holocentridae). The blackbar soldierfish, Myripristis jacobus, has a pelagic juvenile phase of about 58 days, compared to about 71 days (~22% longer) in the longjaw squirrelfish, Holocentrus ascensionis. If the pelagic duration is guiding dispersal ability, M. jacobus should have greater population genetic structure than H. ascensionis. In comparisons of mtDNA cytochrome b sequences from 69 M. jacobus (744 bp) and 101 H. ascensionis (769 bp), both species exhibited a large number of closely related haplotypes (h=0.781 and 0.974, π=0.003 and 0.006, respectively), indicating late Pleistocene coalescence of mtDNA lineages. Contrary to the prediction based on pelagic duration, M. jacobus has much less population structure (φ_ST=0.008, P=0.228) than H. ascensionis (φ_ST=0.091, P<0.001). Significant population partitions in H. ascensionis were observed between eastern, central and western Atlantic, and between Brazil and the Caribbean in the western Atlantic. These results, in combination with the findings from 13 codistributed species, indicate that pelagic larval duration is a poor predictor of population genetic structure in Atlantic reef fishes. A key to understanding this disparity may be the evolutionary depth among corresponding taxonomic groups of “reef fishes”, which extends back to the mid-Cretaceous and encompasses enormous diversity in ecology and life history. We should not expect a simple relationship between pelagic larval duration and genetic connectivity, among lineages that diverged 50–100 million years ago.