Suchergebnisse

This paper is an empirical analysis of the way in which a group of scientists sought to maximize the attractiveness of one of their papers. It records negotiations about the title, the introduction, and the second paragraph (in which a polymer was characterized). The analysis suggests that scientists array or `network' particulars in a way which they hope will allocate appropriate relative value to elements of that array. In doing so, three factors — the citation of colleagues, the display of facts, and problems of syntax — have to be simultaneously juggled.

AbstractThis paper reports the concentrations of the herbicide simazine which were found in a stream draining a small agricultural catchment as a result of normal agricultural practice. The study, part of the National Rivers Authority Research and Development programme, shows that peaks in the concentration of simazine occurred very soon after rainfall events. It goes on to show that although the mass of simazine transported from the catchment during each rainfall event is small as a percentage of that applied (less than 1%), the concentrations observed are far from insignificant. It is suggested that monitoring programmes need to be designed to cover such pesticide pulses generated as the result of rainfall events occurring at times of peak application. Also, more realistic environmental‐quality standards need to be developed and applied where the EC drinking water Directive is inappropriate, and to reflect the intermittent nature of the problem.

This paper provides an introduction to the ecological fabric of northern Australia, described here as being a land characterised by extreme climatic seasonality and largely devoid of marked topographic features. Largely as a result of the latter trait, many species have extensive geographic ranges, and the spatial turnover in species composition is extremely limited. Somewhat counter-intuitively, these two traits can be accommodated by organisms only through reliance on critical, but often subtle, landscape variation. We present some preliminary models for Gouldian finch (Erythrura gouldiae) and black-footed tree-rat (Mesembriomys gouldii) to illustrate patterns of variation in their resource availability, and the consequences of such variation. We discuss briefly some studies that have attempted to integrate, or at least consider, these elements.

AbstractAbandoned mines create pollution problems in rivers as minewater levels rise and discharges of metal‐rich acidic waters occur. Mines adjacent to rivers can cause serious pollution problems, reducing fish stocks and preventing restocking. A computer model has been used to simulate the impact of these discharges and to devise an optimal treatment strategy to meet river quality objectives. The use of this model, through application to two case studies, is described.

ABSTRACTThis paper presents data on the distribution of seven pesticides in an agricultural catchment which is located within the Agricultural Development and Advisory Service farm at Rosemaund, 11 km north‐east of Hereford, UK. Data for aldicarb, atrazine, carbofuran, dimethoate, MCPA and isoproturon, are available for both the soil and surface waters (drain and stream water), with simazine data available only for the stream. Measurements were taken before and after pesticide application, which was made following normal agricultural practice. Soil residue data showed the degradation rates of the pesticides to be within the range of literature values. Pesticide levels in the stream and drains during runoff events following rainfall ranged from below detection limits (typically 0.02‐0.1 μg/1), to 264 μg/1 (for carbofuran). Over 90% of the events had detectable maximum concentrations. The percentage of pesticide applied, which was removed during individual rainfall events, was calculated. The maximum value estimated was 1.1%, again for carbofuran. Most of the events gave values several orders of magnitude below this value.The data have been used to try to validate a range of models which could be used for screening new pesticides or for informing decisions on the use of existing pesticides. The results of the validations are summarized.

ABSTRACTThis paper presents data on the distribution of four herbicides within an agricultural catchment. In the case of mecoprop, 2,4‐dichlorophenoxyacetic acid and simazine, these data include concentrations in the soil, field drains and the stream, before and after applications of the herbicides following good agricultural practice. The concentrations of these herbicides in the soil were found to follow published degradation rates, and their concentrations in the stream and drains were elevated following rainfall with peak concentrations from 0.12 μg/1 to 68.0 μg/1. Atrazine was found at relatively high concentrations (peak 122 μg/1) when it had not been applied to any of the fields draining to the sampling point.The data will be used to test models that may be used as one of a number of tools for the screening of new pesticides prior to their registration. One approach using the Mackay's fugacity model is outlined.

AbstractData are presented on four pesticides applied to agricultural land at the Agricultural Development Advisory Service, Rosemaund, in the west of England. The farm covers a well‐defined and isolated water basin of cracking heavy clay loam soils drained by a single stream. Levels of the relatively particle‐bound pesticides trifluralin, deltamethrin, chlorpyrifos and fenpropimorph were measured in drainage water and field soils following application. Observed concentrations in water were generally below 1 μg/l with occasional peak levels exceeding 10 μg/l during storm rainfall events. Unexpectedly high peak levels of deltamethrin of around 2 μg/l highlighted significant bypass flow mechanisms from the surface soils during the autumn. Additional bioassay experiments showed that levels of chlorpyrifos, lethal to Gammarus pulex, reached the stream during spring 1993. The Rosemaund farm has been the site of a continuing investigation into the movement of agricultural pesticides to surface waters since 1987, and this report represents the final work conducted in the autumn of 1992 and spring 1993.

Human monkeypox is a zoonotic smallpox-like disease caused by an orthopoxvirus of interhuman transmissibility too low to sustain spread in susceptible populations. In February 1997, 88 cases of febrile pustular rash were identified for the previous 12 months in 12 villages of the Katako-Kombe Health Zone, Democratic Republic of Congo (attack rate = 22 per 1,000; case-fatality rate = 3.7%). Seven were active cases confirmed by virus isolation. Orthopoxvirus- neutralizing antibodies were detected in 54% of 72 patients who provided serum and 25% of 59 wild-caught animals, mainly squirrels. Hemagglutination-inhibition assays and Western blotting detected antibodies in 68% and 73% of patients, respectively. Vaccinia vaccination, which protects against monkeypox, ceased by 1983 after global smallpox eradication, leading to an increase in the proportion of susceptible people.