An immunoassay for metolachlor detection in river water and soil.

An indirect enzyme-linked immunosorbent assay (EIA) for metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamid e) detection in river water and soil was developed using serum obtained from rabbits immunized against the acid of metalaxyl ((N-(2,6-dimethylphenyl)-N-(methoxy-acetyl)-DL-alanine methyl ester) conjugated to bovine serum albumin. The assay had a linear working range from 1 to 50 ng/ml with a mean I50 value of 13.6 ng/ml and a lower detection limit of 2.0 ng/ml. Both the mean interwell and interassay coefficients of variation were less than 4% over the range of the standard curves for samples which had been prepared in phosphate buffered saline (PBS), river water, or soil extract. Assay cross-reactivity to the following four structurally related chloro-acetanilide pesticides were: propachlor (0%), metazachlor (0%), alachlor (23%), and metalaxyl (5,000%). Mean recoveries of metolachlor in spiked (2.0 to 32.0 ng/ml range) PBS, river water, and soil extract were 102%, 103%, and 110%, respectively. Soil samples were taken over a 56-d period from field plots treated with metolachlor and analyzed by GC and EIA. The correlation coefficient for comparison of the two methods was 0.96 with the slope of the linear regression line being 0.78. Furthermore, no statistical difference (P less than 0.05) was found between the dissipation curves of metolachlor derived from GC data versus EIA data.     

Environmental life-cycle management emerges

Ecological economic thinking leads us to conclude that instead of being mesmerized into inaction by scientific uncertainty over our future, we should acknowledge uncertainty as a fundamental part of the system. We must develop better methods to model and value ecological goals and services and devise policies to translate those values into appropriate incentives. If we continue to segregate ecology and economics, we are courting disaster.     

Migration of pollutants in groundwater. III. Numerical dispersion reduction with cartesian coordinates

The partial differential equation governing the movement of a decomposing pollutant undergoing 2-dimensional flow in a saturated aquifer is examined. The analytical solution of the equation is usually not possible, and use of mesh numerical integration techniques causes excessive numerical dispersion to arise from the advection term. We apply two asymmetrical upwind formulas to approximate the advection term. These markedly reduce numerical dispersion without requiring the use of coordinate systems obtained by conformal mapping. Flow within a right angle and flow toward a sink in an otherwise uniform field are analyzed to illustrate the methods.     

COMPARATIVE EVALUATION OF STATISTICAL METHODS FOR WATER SUPPLY FORECASTING1

ABSTRACT: While the correlation coefficient and standard error of estimate are frequently used when comparing models of seasonal water yield, the following criteria may be more important in selecting one model from among several alternatives: rationality of the regression coefficients, the distribution of the residual errors, and the correctness of indicators of the relative importance of the predictor variables. These criteria were used to compare seasonal water yield models that were calibrated using multiple regression, stepwise regression, principal components regression, polynomial regression using a principal components rotation, and constrained pattern search. Hydrologic data from the Upper Sevier River basin in southern Utah were used to illustrate the comparative analysis process. The prediction equations used the April-July streamflow volume as the criterion variable.     

Perceived Impacts of Ecotourism on Environmental Learning and Conservation: Turtle Watching as a Case Study

Using a case study, involving turtle-based ecotourism, we explore the role of ecotourism in promoting environmental learning and in sustaining conservation of nature. Mon Repos Conservation Park (an important marine turtle rookery involved in ecotourism) in Queensland, Australia, was selected for this study and visitors were surveyed using a structured questionnaire. The reported on-site experiences of respondents are analysed to identify important factors that alter their stated conservation attitudes and behaviours. The impact of these factors (such as the amount of environmental education that respondents claimed they obtained, sighting of sea turtles, nationality) is quantified using regression analyses. There has been little previous quantification of such influences. The study reveals that a considerable amount of environmental knowledge is gained by visitors to Mon Repos. The ecotourism experience, involving environmental education and seeing of turtles, was found to have positive and statistically significant impacts on the visitors' stated desire and intended behaviour to protect sea turtles. The study reveals the importance of learning and the interaction of tourists with wildlife as a contributor to their pro-conservation sentiments and actions. It shows how ecotourism can support nature conservation. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Dispersion of Tellina tenuis from Kames Bay,Millport, Scotland

The dispersion of Tellina tenuis da Costa in the laboratory was analysed by the Clark and Evans nearest-neighbour test and by the Kolmogorov-Smirnov one-sample test. The dispersion was random, with a slight tendency toward aggregation that was independent of density. In the field, the dispersion was analysed by the Clark and Evans nearest-neighbour test and by the X² approximation to Fisher's coefficient of dispersion. The dispersion was again random, this time with a slight tendency toward spacing out that was independent of density. The tendency toward aggregation displayed in the laboratory was independent of the dispersion pattern shown at the start of the experiment, and also unaffected by the edge of the container. The apparent randomness suggests that T. tenuis is primarily a suspension feeder, but may be a deposit feeder under certain environmental conditions.     

Jellyfish aggregations and leatherback turtle foraging patterns in a temperate coastal environment

Leatherback turtles (Dermochelys coriacea) are obligate predators of gelatinous zooplankton. However, the spatial relationship between predator and prey remains poorly understood beyond sporadic and localized reports. To examine how jellyfish (Phylum Cnidaria: Orders Semaeostomeae and Rhizostomeae) might drive the broad-scale distribution of this wide ranging species, we employed aerial surveys to map jellyfish throughout a temperate coastal shelf area bordering the northeast Atlantic. Previously unknown, consistent aggregations of Rhizostoma octopus extending over tens of square kilometers were identified in distinct coastal "hotspots" during consecutive years (2003-2005). Examination of retrospective sightings data (>50 yr) suggested that 22.5% of leatherback distribution could be explained by these hotspots, with the inference that these coastal features may be sufficiently consistent in space and time to drive long-term foraging associations.     

Young driver risk in relation to parents' retrospective driving record

PROBLEM: Parents are an important potential influence on the driving safety of their children. This study examined the relationship of parental driving record on male and female offspring's at-fault collision risk. METHOD: Drivers aged 16-21 on the date of full licensure were selected from driver records and a matching process was used to identify putative parents in two-parent households. Poisson regression models were developed to predict at-fault collisions of male and female youth in the three years following full licensure from parents' at-fault collisions, speeding offenses, and other moving offenses in the four years prior to children's licensure. One set of models examined the relative risk associated with increasing numbers of maternal and paternal at-fault collisions and offenses. Other models examined the joint versus separate maternal and parental contributions. RESULTS: Controlling for region of residence, both mothers' and fathers' at-fault collisions were associated with an increased risk in both male and female youth at-fault collisions. Mothers' and fathers' speeding offenses were also associated with increased relative risk of at-fault collisions for both sons and daughters, while fathers' other moving offenses increased collision risk for sons but not daughters. DISCUSSION: Further research is required to identify how parental driving risk is transmitted to children. IMPACT ON INDUSTRY: (a) Parents of young children should be informed of their role in influencing their children's future driving risk; (b) The results identify risk factors that could be of interest to licensing authorities and the insurance industry.