Efficient search procedures for extreme pollutant values

Extreme pollutant values are of great interest in water quality monitoring because of their frequent toxicological significance. The principal barrier to the detection of these values, however, is the cost of extensive and comprehensive monitoring. This paper demonstrates an efficient method to determine the maximum sample measurement from a finite set of sequential samples without explicitly testing them all. It is assumed that the process of sample measurement is distinct from collection and has higher costs. It is further assumed that the measurements have high positive autocorrelation.A methodology is presented based on a common industrial testing procedure referred to as composite sampling—the physical pooling or compositing of a set of sequential samples before measurement. A method known as primary first order compositing (PFOC) was found to be superior to the traditional technique of random sampling, particularly if small composite sizes are utilized.The authors are, respectively, operations research analyst, Vancouver, B. C.; Associate Professor and Chairman, Policy Analysis Division, Faculty of Commerce and Business Administration, University of British Columbia; and Associate Professor, Management Science Division, Faculty of Commerce, U.B.C.     

Assessing the long-term supply risks for mineral raw materials—a combined evaluation of past and future trends

This paper develops a method for identifying and assessing long-term supply risks for mineral raw materials. The method is based on a combined evaluation of past and future supply and demand trends. By analysing raw material boom and bust cycles over the past 50 years, we have quantified indicators and defined benchmarks for identifying critical market situations. By applying the method, risks for supply shortage may be identified at an early stage. In addition, a numerical evaluation model has been developed for better comparison between various mineral raw materials. Compared to other assessment methods this method uses specific benchmarks for each raw material to better assess supply risks. The method is embedded within a systematic and comprehensive analytical approach.     

Rapid detection of toxic metals in non-crushed oyster shells by portable X-ray fluorescence spectrometry

The aim of this study was the multi-elemental detection of toxic metals such as lead (Pb) in non-crushed oyster shells by using a portable X-ray fluorescence (XRF) spectrometer. A rapid, simultaneous multi-element analytical methodology for non-crushed oyster shells has been developed using a portable XRF which provides a quick, quantitative, non-destructive, and cost-effective mean for assessment of oyster shell contamination from Pb. Pb contamination in oyster shells was further confirmed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). The results indicated that Pb is distributed in-homogeneously in contaminated shells. Oyster shells have a lamellar structure that could contribute to the high accumulation of Pb on oyster shells.     

A review of regulations and guidelines related to winter manure application

Winter manure application elevates nutrient losses and impairment of water quality as compared to manure applications in other seasons. In conjunction with reviewing global distribution of animal densities, we reviewed worldwide mandatory regulations and voluntary guidelines on efforts to reduce off-site nutrient losses associated with winter manure applications. Most of the developed countries implement regulations or guidelines to restrict winter manure application, which range from a regulative ban to guidelines based upon weather and field management conditions. In contrast, developing countries lack such official directives, despite an increasing animal production industry and concern over water quality. An analysis of five case studies reveals that directives are derived from a common rationale to reduce off-site manure nutrient losses, but they are also affected by local socio-economic and biophysical considerations. Successful programs combine site-specific management strategies along with expansion of manure storage to offer farmers greater flexibility in winter manure management.     

Modeling kelp forest distribution and biomass along temperate rocky coastlines

We address the global deficit of data describing kelp forest distribution, relative covers and biomass by testing the ability of species distribution models to predict these attributes at locations where data are currently limited. We integrated biological ground truth data with high-resolution environmental datasets to develop generalized additive models that accurately predict the structure of Laminaria forests within the Bay of Morlaix (48°42′42″N, 3°55′40″W). Forest distribution and proportional covers were predicted using water depth, light availability, wave exposure and sediment dynamics. The biomass of individual kelp species was modeled by supplementing these same variables with measures of seafloor slope and benthic position. Biomass predictions for Laminaria digitata and Laminaria hyperborea contrast the physiological tolerances of these species to light and wave exposure gradients. As a direct management output, we produced high-resolution maps (25 m² grids) that closely match independent field data and provide vital information for marine spatial planning.     

The role and expectancy participation model: An empirical assessement and extension

Four hypotheses were investigated. The results substantially support and extend the usefulness of Schuler's role and expectancy participation model (1980). Schuler's model posits that participation intervenes to attenuate the relationships between job objectives and role conflicts and ambiguity. Also, participation, role conflict and role ambiguity are assumed to intervene to attenuate the relationships between job objectives and job satisfaction. The four hypotheses were tested using a sample of 187 retail store managers. Results revealed that job objectives were related to the role variables and satisfaction. Participation significantly attenuated the job objectives, role conflict and job satisfaction relationships. Implications for the use of the attributes of job objectives approach to integrate other objective setting paradigms are discussed.     

BASIN WATER MONITORING: HYDROLOGIC IMPACT OR LEGAL COMPLIANCE1

ABSTRACT: The Surface Mining Control and Reclamation Act of 1977 (PL 95–87) requires data collection prior to mining which will allow a determination to be made of the probable hydrologic consequences. Modeling strategies exist which allow for such determination, but selection of a specific model form will dictate the length of data record needed. The absence of a sound management strategy by the regulatory authority in‘Maryland does not result in valid data collection and suggests that the agency is concerned more with legal compliance than with integrated resource management.     

Field dissipation of acetochlor in two New Zealand soils at two application rates

The persistence of pesticides in soils has both economic and environmental significance and is often used as a key parameter in pesticide risk assessment. Persistence of acetochlor [2'-ethyl-6'-methyl-N-(ethoxymethyl)-2-chloroacetylanilide] in two New Zealand field soils was measured over two years and the data were used to identify models that adequately describe acetochlor persistence in the field. Acetochlor was sprayed onto six fallow plots (3 x 9 m each) at each site at the recommended rate (2.5 kg a.i. ha(-1)) and at twice that rate. Acetochlor concentrations were measured in soil cores. Simple first-order kinetics (Model 1) adequately described acetochlor persistence in Hamilton clay loam soil (Humic Hapludull, Illuvial Spadic) at the high application rate, but overestimated it at the low application rate. A quadratic model (Model 2), a first-order double-exponential model (Model 3), a first-order biphasic model (Model 4), or a two-compartment model (Model 5) better described acetochlor persistence at the low application rate. The time for 50% (DT50) and 90% (DT90) of initial acetochlor loss was approximately 9 and 56 d, and 18 and 63 d at low and high application rates, respectively. The more complex Models 2 through 5 also better described the biphasic dissipation of acetochlor in Horotiu sandy loam soil (Typic Orthic Allophanic) than Model 1, with Model 1 significantly underestimating acetochlor concentrations on the day of application at both application rates. The DT50 and DT90 values were 5 and 29 d and 7 and 31 d at low and high application rates, respectively. Overall, application rate significantly affected the DT50 and DT90 values in the Hamilton soil, but not in the Horotiu soil. Faster acetochlor loss in the Horotiu soil possibly resulted from the higher soil organic carbon content that retained more acetochlor near the soil surface where higher temperature and photolysis accelerated the loss.     

A new device for measuring fluctuations in plant stem diameter: Implications for monitoring plant responses

An electrical device capable of continuously measuring micronsized changes in stem diameter of woody and herbaceous plants is described. Fumigation of sunflowers with automotive exhaust was used to test the ability of the device to detect short-term plant responses.