Spatial Relationships Between Water Quality and Pesticide Application Rates in Agricultural Watersheds

Pesticide applications to agricultural lands in California, USA, are reported to a central data base, while data on water and sediment quality are collected by a number of monitoring programs. Data from both sources are geo-referenced, allowing spatial analysis of relationships between pesticide application rates and the chemical and biological condition of water bodies. This study collected data from 12 watersheds, selected to represent a range of pesticide usage. Water quality parameters were measured during six surveys of stream sites receiving runoff from the selected watershed areas. This study had three objectives: to evaluate the usefulness of pesticide application data in selecting regional monitoring sites, to provide information for generating and testing hypotheses about pesticide fate and effects, and to determine whether in-stream nitrate concentration was a useful surrogate indicator for regional monitoring of toxic substances. Significant correlations were observed between pesticide application rates and in-stream pesticide concentrations (p < 0.05) and toxicity (p < 0.10). In-stream nitrate concentrations were not significantly correlated with either the amount of pesticides applied, in-stream pesticide concentrations, or in-stream toxicity (all p > 0.30). Neither total watershed area nor the area in which pesticide usage was reported correlated significantly with the amount of pesticides applied, in-stream pesticide concentrations, or in-stream toxicity (all p > 0.14). In-stream pesticide concentrations and effects were more closely related to the intensity of pesticide use than to the area under cultivation.     

Roles of interplant movement,acoustic communication,and phototaxis in mate-location behavior of the leafhopper Graminella nigrifrons

Summary Male Graminella nigrifrons leafhoppers (Cicadellidae: Homoptera) employ a call-fly strategy to find virgin females on oat host plants. Males observed in isolation during daylight hours exhibit a high rate of interplant movement, calling from the lower canopy on each plant visited. Virgin and mated females exhibit little interplant movement. They differ from one another in that virgin females perch on the upper half of plants, whereas mated females perch on the lower half of plants. The positioning of females in the plant canopy is influenced by light. Unlike mated females, virgin females respond to male calls by emitting their own acoustic signals. When virgin females are present on plants visited by males, interplant movement of males ceases, and a localized-upward search of the female bearing plant ensues. Male search is influenced by light. Regardless of whether virgin females were confined to the upper or lower portion of plants, direction of male search was towards a light source used to illuminate above or below the plant canopy. These findings suggest that interplant movement by males and sedentary behavior by females prior to mate recognition and their use of acoustic and phototactic sensory modalities after mate recognition represent previously unrecognized adaptations to problems associated with the use of vibrational signals on plants. Offprint requests to: R.E. Hunt at the current address     

Business ideologies and perceived breach of contract during downsizing: the role of the ideology of employee self‐reliance

This paper represents an initial effort to explore the empirical relationship between business ideologies and perceptions of organizational downsizing. The results of four studies, two conducted in the US and one each in Singapore and Korea, suggest that respondents' belief in the ideology of employee self‐reliance reduces the degree to which they perceive layoffs as a breach of the psychological contract. This finding appears to generalize to respondents' perceptions of their own layoffs and also to respondents' perceptions of layoffs happening to others. We spell out the implications of these results for the evolving theory of the ideological foundations of perceptions of downsizing. Copyright © 2003 John Wiley & Sons, Ltd.     

Fuzzy input–output model for optimizing eco-industrial supply chains under water footprint constraints

Global water stress is expected to increase due to population growth, economic development and climate change. Because of this trend, there is an increased interest in the water intensity of industrial activities conducted via the product supply chain or within specified geographical boundaries or regions, both at the enterprise- or regulatory-level. The total water footprint of economic activities should be evaluated in consideration of local water resource consumption, virtual water trade and resource availability. As individual entities seek to protect their respective interests, the challenge is to optimize inter-regional trade of goods with the consideration of the interests of participants in the network. This work presents a fuzzy input–output model for optimizing supply chains under water footprint constraints. Two case studies, involving tile manufacturing and biofuel production, are considered to demonstrate the use of the model.     

Supercritical fluid extraction of polycyclic aromatic hydrocarbons from white pine (Pinus strobus) needles and its implications

A supercritical fluid extraction (SFE) method was developed for the extraction of polycyclic aromatic hydrocarbons (PAHs) from fresh and fallen pine needles. Toluene-modified CO2 was used as the extracting fluid, and the extracted PAHs were analyzed by GC-MS. Using a two-stage extraction procedure, a static extraction at 180 degrees C and a dynamic extraction at 60 degrees C, and an in-cell silica gel plug plus a post-oven silica gel column, the extraction and fractionation of PAHs can be accomplished in one step. Over a seven month period, a significant variation was observed for PAHs in urban samples, while PAHs in mountain samples were at much lower levels (by a factor of approximately 8) and showed little seasonal change. Although dry fallen needles and fresh needles contained similar amounts of PAHs, in the fallen needles the lower molecular weight PAHs were partially lost while the higher molecular weight PAHs were slightly enriched. Pollution in urban areas was found to be highly localized, and buildings and trees are believed to be important factors in the restriction of atmospheric PAHs.     

Effect of sunlight intensity and albinism on the covering response of the Caribbean sea urchin<Emphasis Type="Italic"> Tripneustes ventricosus</Emphasis>

At Discovery Bay, Jamaica, Tripneustes ventricosus lives in beds of the turtle grass Thalassia testudinum. Especially during daylight hours, it covers its aboral surface with fragments of this plant and other objects. Normally pigmented, wild-type sea urchins covered themselves significantly less with Thalassia when sunlight was experimentally decreased to 66% or 32% ambient intensity. Consistent with this result, naturally occurring sea urchins exhibited significantly less covering at a deep (3.5 m) site than at a shallow (1 m) site, where light intensities at the bottom were 619 and 946 mol s^–1 m^–2, respectively. The graded covering response to light intensity suggests that covering is a defense against damaging solar radiation. Albino sea urchins covered themselves significantly more with Thalassia than wild-type sea urchins in both full and 66% sunlight. In addition, at the shallow site where they accounted for about 4% of the population, they showed significantly greater covering than wild-type urchins. The greater covering response of albino sea urchins suggests a greater susceptibility to solar radiation.Communicated by P. W. Sammarco, Chauvin     

Assessment of prospective foodchain doses from radioactive discharges from BNFL Sellafield

This paper presents the method used by the UK Food Standards Agency (FSA) to assess the potential impact of proposed radioactive discharges from the Sellafield nuclear site on food and determine their acceptability. It explains aspects of a cautious method that has been adopted to reflect the UK government policy and uncertainties related to people's habits with regard to food production and consumption. Two types of ingestion doses are considered in this method: 'possible' and 'probable' doses. The method is specifically applied to Sellafield discharge limits and calculated possible and probable ingestion doses are presented and discussed. Estimated critical group ingestion doses are below the dose limit and constraint set for members of the public. The method may be subject to future amendments to take account of changes in government policy and the outcome of a recent Consultative Exercise on Dose Assessments carried out by FSA. Uncertainties inherent in dose assessments are discussed and quantified wherever possible.