A study of the quantitative analysis of herbicide residues by both chemical and bioassay methods in soils is presented. Field and laboratory residue trials were carried out with a representative member of the following groups of herbicides: ureas, triazines, diphenylethers, phenoxyacetic acids, and dithiophosphates. Representative samples were taken at different time intervals, and degradation curves were established both by chemical methods and by two types of bioassay. Chemical analysis either separated active ingredient and metabolites by chromatographic techniques or compresied total residues. Bioassays were performed using either monocotyledons and dicotyledons or algae. The results obtained by chemical and bioassay analysis for the degradation rates of chlorotoluron, ametryn, 2,4-D and C 19490 showed a correlation coefficient of 0.914, indicating that the two methods gave almost identical results. Especially with the highly adsorbed urea and triazine herbicides, the uptake of biologically active material by test plants was slightly less than the solvent-extractable parent compound plus its metabolities, and so the absolute level of residues obtained by bioassay was lower. In the case of fluorodifen, the correlation between the methods was not established. The bioassay showed higher residues and slower degradation than chemical analysis. Various factors which could explain this anomalous result are discussed.
We present Communiplay, a public display media space. People passing by see their own contour mirrored on a public display and can start to play with virtual objects. At the same time, they see others playing at remote displays within the same virtual space. We are interested whether people would use such a public display media space, and if so, how and why. We evaluate Communiplay in a field study in six connected locations and find a remote honey-pot effect, i.e. people interacting at one location attract people at other locations. The conversion rate (percentage of passers-by starting to interact) rose by +136% when people saw others playing at remote locations. We also provide the first quantification of the (local) honey-pot effect (in our case it raised the conversion rate by +604% when people saw others playing at the same location). We conclude that the integration of multiple public displays into a media space is a promising direction for public displays and can make them more attractive and valuable.
A gas chromatographic multiresidue method is described for the following triazine herbicides: ametryn, atraton, atrazine, desmetryn, metoprotryn, GS-13529, GS-14254, terbutryn, prometon, prometryn, propazine, and simazine. The method consists of a methanol extraction, cleanup on an alumina column, and determination on a Carbowax column with nitrogen-, sulfur-, and chloride-specific detectors. Extraction and recovery data are given.
Complete automation of extraction, cleanup, and GLC determination of residue analysis of some important triazine herbicides in soils has been achieved. Manually sieved soil samples are continuously delivered to the system, which presents cleaned up extracts to an automated GLC injection system. Peak areas are calculated by a digital electronic integrator. The output of the integrator is connected to a teletype printer which generates both printed hard copy and a punched paper tape in standard ASCII code. This information is fed by a punchtape reader into a programmed Wang 700 desktop computer. Final analysis reports are printed by an attached typewriter. The system allows a 4-fold output of analytical results with half the personnel compared to manual analysis.
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