The Influence of Urban Density and Drainage Infrastructure on the Concentrations and Loads of Pollutants in Small Streams

Effective water quality management of streams in urbanized basins requires identification of the elements of urbanization that contribute most to pollutant concentrations and loads. Drainage connection (the proportion of impervious area directly connected to streams by pipes or lined drains) is proposed as a variable explaining variance in the generally weak relationships between pollutant concentrations and imperviousness. Fifteen small streams draining independent subbasins east of Melbourne, Australia, were sampled for a suite of water quality variables. Geometric mean concentrations of all variables were calculated separately for baseflow and storm events, and these, together with estimates of runoff derived from a rainfall-runoff model, were used to estimate mean annual loads. Patterns of concentrations among the streams were assessed against patterns of imperviousness, drainage connection, unsealed (unpaved) road density, elevation, longitude (all of which were intercorrelated), septic tank density, and basin area. Baseflow and storm event concentrations of dissolved organic carbon (DOC), filterable reactive phosphorus (FRP), total phosphorus (TP) and ammonium, along with electrical conductivity (EC), all increased with imperviousness and its correlates. Hierarchical partitioning showed that DOC, EC, FRP, and storm event TP were independently correlated with drainage connection more strongly than could be explained by chance. Neither pH nor total suspended solids concentrations were strongly correlated with any basin variable. Oxidized and total nitrogen concentrations were most strongly explained by septic tank density. Loads of all variables were strongly correlated with imperviousness and connection. Priority should be given to low-impact urban design, which primarily involves reducing drainage connection, to minimize urbanization-related pollutant impacts on streams.     

Ethical problems in prenatal diagnosis: A cross-cultural survey of medical geneticists in 18 nations

In order to provide a basis for international discussion of ethics among geneticists, we surveyed the responses of medical geneticists to a questionnaire describing 14 hypothetical cases that posed ethical dilemmas. The cases were selected through discussions with leading geneticists in 12 nations, as representative of the most difficult problems of moral choice experienced in practice. Six cases involved indications for prenatal diagnosis or disclosure of information. All medical geneticists in each of 18 nations were included. Of 1053 asked to participate, 677 (64 per cent) responded. A large majority (83 per cent) would perform prenatal diagnosis for parents who oppose abortion but request the service. A smaller majority (63 per cent) would do so for maternal anxiety, and a minority (25 per cent) would perform for sex selection in the absence of X-linked disease. Most would disclose conflicting controversial, or ambiguous test results, and two-thirds would disclose colleagues' differences of opinion.     

Application of the wilderness travel simulation model to the Appalachian Trail in Vermont

The wilderness travel simulation model estimates complex recreation use patterns in park and wilderness environments. The model was applied to a section of the Appalachian Trail in Vermont, a linear, long-distance, multiple-access trail system characteristic of the eastern United States. Many portions of the trail, including the study area, are now experiencing high use. The model estimated the average number of trail encounters per party day to be 3.3 and the average number of camp encounters per party night to be 2.3. Other measures of recreation use were also estimated that should prove useful to trail management and administration. Three trail management scenarios were tested, providing several preliminary insights to managers: the desirability of use redistributions as opposed to across-the-board reductions and needed emphasis on spatial use patterns and campsite encounters. Only minor modifications to the program were needed in applying the model to the trail environment and the model functioned accurately according to the validity tests performed.     

A refutation of Karasek's demand – discretion model of occupational stress with a range of dependent measures

Karasek's (1979) demand–discretion model of occupational stress has been highly influential but has been criticized as confounding social class variables (Payne and Fletcher, 1983), ignoring the curvilinearity of relationships (Warr, 1991), and because it has inconsistently predicted heart disease (Ganster and Fusilier, 1989). The present study examines the ability of the model to predict raised blood pressure (a risk factor in the development of CHD), anxiety, depression, job and life satisfaction, in a large heterogeneous sample of over 3000 people. It examines the predictability of the model for men and women, taking occupational classification (manual and non-manual workers) into account, to allow some control over social class confounding. It also examines nonlinear relationships in the data. The study showed that demands and discretion do separately predict psychological strain, job and life satisfaction, though they account for a very small percentage of the variance. There was no evidence of interactive effects which are central to the model. Where the model was able to predict blood pressure, relationships were consistently in the opposite direction to that hypothesized. There was also little evidence of curvilinear relationships. Interpersonal support was found to add significantly to the predictability of the dependent variables. The findings cast doubt on Karasek's model and suggest that emphasis should be shifted to those models which are more encompassing of support factors.     

Duty hours and incidents in flight among commercial airline pilots

Introduction. Working long duty hours has often been associated with increased risk of incidents and accidents in transport industries. Despite this, information regarding the intermediate relationship between duty hours and incident risk is limited. This study aimed to test a work hours/incident model to identify the interplay of factors contributing to incidents within the aviation industry. Methods. Nine hundred and fifty-four European-registered commercial airline pilots completed a 30-item survey investigating self-report attitudes and experiences of fatigue. Path analysis was used to test the proposed model. Results. The fit indices indicated this to be a good fit model (χ²?=?11.066, df?=?5, p?=?0.05; Comparative Fit Index?=?0.991; Normed Fit Index?=?0.984; Tucker–Lewis Index?=?0.962; Root Mean Square of Approximation?=?0.036). Highly significant relationships were identified between duty hours and sleep disturbance (r?=?0.18, p?r?=?0.40, p?r?=?0.43, p?Discussion. A critical pathway from duty hours through to self-reported incidents in flight was identified. Further investigation employing both objective and subjective measures of sleep and fatigue is needed.     

Converting Toxic Equivalents (TEQ) of dioxins and dioxin-like compounds in fish from one Toxic Equivalency Factor (TEF) scheme to another

Toxic Equivalency Factors (TEFs) are an essential part of the Toxic Equivalent (TEQ) concept and have evolved for dioxins/dioxin-like compounds over the last two and half decades. Therefore, it is difficult to compare past and current TEQs that are reported using different TEFs without explicitly mentioning underlying congener concentrations. Using what likely is the largest known dioxin/furan (PCDD/F) and dioxin-like polychlorinated biphenyl (dl-PCB or DLP) fish database, here we present regression models that can facilitate conversion of a fish TEQ from an old to a newer TEF scheme. The results show that the mammalian PCDD/F-TEQ based on the latest TEF(WHO-05) is about 7.5% lower than that based on TEF(WHO-98). The mammalian DLP-TEQ(WHO-05) is on average 25-26% lower than almost identical DLP-TEQ(WHO-94) and DLP-TEQ(WHO-98). Total-TEQ(WHO-05) is on average 22% lower than Total-TEQ(WHO-98). According to the current toxicological standards for dioxins/furans, all previous major TEF schemes except TEF(Germany-85) and TEF(USEPA-87) were conservative (i.e., higher) in estimating TEQs. The major (> 75%) contribution to PCDD/F-TEQ(WHO-05) is from 2,3,7,8-TCDD (33%), 1,2,3,7,8-PCDD (26%), 2,3,7,8-TCDF (10%), and 2,3,4,7,8-PCDF (9%). The DLP-TEQ(WHO-05) is dominated by PCB-126 which on average contributes about 88%. The DLP-TEQ generally contribute > 70% of Total-TEQ. When reporting TEQs, we recommend that the underlying congener specific concentrations are presented, TEF scheme used is clearly stated, names of compounds included are explicitly expressed, and TEQs are identified accordingly (e.g., DLP-TEQ, PCDD/F-TEQ, Total-TEQ).     

Use of DNA barcoding to reveal species composition of convenience seafood

Increased education of consumers can be an effective tool for conservation of commercially harvested marine species when product labeling is accurate and allows an informed choice. However, generic labeling (e.g., as white fish or surimi) and mislabeling of seafood prevents this and may erode consumer confidence in seafood product labels in general. We used DNA barcoding to identify the species composition of two types of convenience seafood (i.e., products processed for ease of consumption): fish fingers (long pieces of fish covered with bread crumbs or batter, n = 241) and seafood sticks (long pieces of cooked fish, n = 30). In products labeled as either white fish or surimi, four teleost species were present. Less than 1.5% of fish fingers with species-specific information were mislabeled. Results of other studies show substantially more mislabeling (e.g., >25%) of teleost products, which likely reflects the lower economic gains associated with mislabeling of convenience seafood compared with whole fillets. In addition to species identification, seafood product labels should be required to contain information about, for example, harvesting practices, and our data indicate that consumers can have reasonable confidence in the accuracy of the labels of convenience seafood and thus select brands on the basis of information about current fisheries practice.     

Assessment of monitoring power for highly mobile vertebrates

Monitoring of population trends is a critical component of conservation management, and development of practical methods remains a priority, particularly for species that challenge more standard approaches. We used field-parameterized simulation models to examine the effects of different errors on monitoring power and compared alternative methods used with two species of threatened pteropodids (flying-foxes), Pteropus conspicillatus and P. poliocephalus, whose mobility violates assumptions of closure on short and long timescales. The influence of three errors on time to 80% statistical power was assessed using a Monte Carlo approach. The errors were: (1) failure to count all animals at a roost, (2) errors associated with enumeration, and (3) variability in the proportion of the population counted due to the movement of individuals between roosts. Even with perfect accuracy and precision for these errors only marginal improvements in power accrued (-1%), with one exception. Improving certainty in the proportion of the population being counted reduced time to detection of a decline by over 6 yr (43%) for fly-out counts and almost 10 yr (71%) for walk-through counts. This error derives from the movement of animals between known and unknown roost sites, violating assumptions of population closure, and because it applies to the entire population, it dominates all other sources of error. Similar errors will accrue in monitoring of a wide variety of highly mobile species and will also result from population redistribution under climate change. The greatest improvements in monitoring performance of highly mobile species accrue through an improved understanding of the proportion of the population being counted, and consequently monitoring of such species must be done at the scale of the species or population range, not at the local level.     

Variability in the chemistry of private drinking water supplies and the impact of domestic treatment systems on water quality

Tap water from 497 properties using private water supplies, in an area of metalliferous and arsenic mineralisation (Cornwall, UK), was measured to assess the extent of compliance with chemical drinking water quality standards, and how this is influenced by householder water treatment decisions. The proportion of analyses exceeding water quality standards were high, with 65 % of tap water samples exceeding one or more chemical standards. The highest exceedances for health-based standards were nitrate (11 %) and arsenic (5 %). Arsenic had a maximum observed concentration of 440 µg/L. Exceedances were also high for pH (47 %), manganese (12 %) and aluminium (7 %), for which standards are set primarily on aesthetic grounds. However, the highest observed concentrations of manganese and aluminium also exceeded relevant health-based guidelines. Significant reductions in concentrations of aluminium, cadmium, copper, lead and/or nickel were found in tap waters where households were successfully treating low-pH groundwaters, and similar adventitious results were found for arsenic and nickel where treatment was installed for iron and/or manganese removal, and successful treatment specifically to decrease tap water arsenic concentrations was observed at two properties where it was installed. However, 31 % of samples where pH treatment was reported had pH < 6.5 (the minimum value in the drinking water regulations), suggesting widespread problems with system maintenance. Other examples of ineffectual treatment are seen in failed responses post-treatment, including for nitrate. This demonstrates that even where the tap waters are considered to be treated, they may still fail one or more drinking water quality standards. We find that the degree of drinking water standard exceedances warrant further work to understand environmental controls and the location of high concentrations. We also found that residents were more willing to accept drinking water with high metal (iron and manganese) concentrations than international guidelines assume. These findings point to the need for regulators to reinforce the guidance on drinking water quality standards to private water supply users, and the benefits to long-term health of complying with these, even in areas where treated mains water is widely available.     

More than money: how multiple factors influence householder participation in at-source stormwater management

Urban stormwater run-off is a threat to stream ecosystems. New approaches to stormwater management aim to protect urban streams from such impacts, by retaining, treating and using stormwater at its source. As up to ～50% of runoff from urban surfaces comes from private property, fostering stormwater retention requires effective householder engagement. We evaluated householder participation in the Little Stringybark Creek project, a stormwater retrofit programme aimed at waterway protection, using qualitative enquiry through formal and informal interviews to identify factors that influenced participation. Participation was governed by multiple factors, with financial incentives and personal co-benefits of tanks primary motivators, while process complexity and distrust were primary barriers. Results suggest an approach combining education to encourage review of subjective norms and attitudes, with incentives to mitigate behavioural controls can transform public behaviour towards sustainable stormwater management.