The effect of fluorescent tracers on droplet spectrum,viscosity, and density of pesticide formulations

The most important factor affecting efficacy and drift of pesticide applications is the droplet spectrum. To measure pesticide drift, researchers utilize fluorescent tracers to rapidly quantify spray deposition. Although fluorescent tracers have been used for more than 50 years, no experiments have been performed on the effect they have on the properties of pesticide formulations (density and viscosity) or droplet spectrum, which affect the drift of pesticides. Therefore, we examined the effect of an oil- and water-based tracer on the volume median diameter (VMD), viscosity, and density of oil- and water-based pesticide formulations. In addition, we experimentally fit and demonstrate the utility of using distributions to characterize pesticide droplet spectra. The addition of tracers to both water- and oil-based formulations did not significantly alter the VMD, viscosity, and density. Lognormal distributions provided the best fit for the water- and oil-based formulations with and without tracer. Our results demonstrated that the addition of oil- and water-based tracers do not significantly alter pesticide formulations properties and droplet spectrum, and most likely do not alter the movement of pesticide droplets in the environment.     

Determination of pendimethalin (PROWL®480 EC) spray drift from ground applications

Abstract

Pendimethalin herbicide (PROWL^®480 EC) spray drift was determined from ground applications representing the highest rate applied to corn in eastern Canada. A novel drift collector pattern was laid out on the ground immediately before herbicide application. Most of the drift collectors were located downwind of the application target area. The maximum labelled rate of 1.68 kg ai/Ha was applied on 2 occasions on separate sites. In both applications, drift collector cards indicated that concentrations of pendimethalin were not detectable outside the target zone (<0.01 μg/cm²) at or beyond the 10 metre drift collector stations. Risk assessment calculations indicated that non‐target organisms would not be at significant risk from off‐site movement of pendimethalin.     

浮码头钢趸船防腐涂装体系研究

目的为浮码头钢趸船优选防腐涂装体系,以延长其使用寿命。方法根据钢趸船腐蚀环境特点,对选用的防腐涂料进行对比试验,针对不同的腐蚀环境,优选不同的防腐蚀方案。结果制定了4套与不同腐蚀环境相对应的防腐涂装体系。结论该防腐蚀涂装体系已在上海、青岛、湛江等海域的钢趸船上使用,效果良好。     

“空地一体化”环境应急监测与管理系统设计

在总结我国环境应急管理体系建设现状的基础上,提出了"空地一体化"的环境应急监测与管理体系的框架和功能设计,介绍了引入无人机监测系统对环境应急体系的功能改进。最后从无人机机载传感器、"空地一体化"数据分析处理和通讯保障3个维度对关键技术的选择问题进行了探讨,分析了其现状、技术难点与发展趋势,以期为现代化的环境应急体系建设提供有益的参考。     

A land management history for central Queensland,Australia as determined from land-holder questionnaire and aerial photography

Features of the land management history over a 125,755 km(2) area of central Queensland, Australia were determined from a variety of sources. A random sample of 205 site locations provided the basis for determining trends in land use. Trends in vegetation clearing were determined using sequential aerial photography for the sample sites, revealing a steady rate averaging nearly 1% of the region per annum over 41 years. This measure of sustained clearing over a large region is higher than recently published clearing rates from South America. Land types have been selectively cleared with over 90% of the Acacia on clay land type having been cleared. A land-holder questionnaire pertaining to the random sites yielded a response rate of 71% and provided information on vegetation clearing, ploughing, tree killing (ring-barking or tree poisoning), and fire frequency, season and intensity. The land-holder responses were compared with independent data sources where possible and revealed no mis-information. However, land-holders may have been marginally less likely to respond if the sample area had been cleared, although this effect was not statistically significant. Ploughing and tree killing are variable depending on land type, but the former has affected about 40% of the Acacia on clay land type, effectively eliminating options for natural regrowth. The proportion of decade-site combinations that were reported as having no fires increased from 22% in the 1950s to an average of 42% for subsequent decades, although the reporting of more than one fire per decade has been relatively constant through the study period. The reporting of at least one fire per decade varies from 46% for the Acacia on sand land type to 77% for the Eucalypt on sand land type for decade-site combinations. Fires are more intense when associated with clearing than in uncleared vegetation, but the proportion of cool and hot fires is relatively constant between land types in uncleared vegetation. Nearly all fires reported were either in spring or summer and this seasonally restricted regime is probably at variance with Aboriginal fire regimes. This study describes the rapid transformation of central Queensland. This has yielded substantially increased agricultural production but may also result in a range of negative impacts and these are discussed.     

Modelling trends in woody vegetation structure in semi-arid Australia as determined from aerial photography

Accounting of carbon stocks in woody vegetation for greenhouse purposes requires definition of medium term trends with accurate error assessment. Tree and shrub cover was sampled through time at randomly located sites over a large area of central Queensland, Australia using aerial photography from 1945 to 1999. Calibration models developed from field data for the same land types as those represented within the study area allowed for the extrapolation of overstorey and understorey cover, basal area and biomass values and these were modelled as trends over the latter half of the 20th century. These structural attributes have declined over the region because of land clearing with values for biomass changing from a mean of 58.0(+/-1.2)t/ha in 1953 to 41.1(+/-1.0)t/ha in 1991. The biomass of Acacia on clay and Eucalypt on texture contrast soils land types has declined most dramatically. Within uncleared vegetation there was an overall trend of increase from 56.1(+/-1.2)t/ha in 1951 to 67.6(+/-1.3)t/ha in 1995. The increase in structural attributes within uncleared vegetation was most pronounced for the Eucalypt on texture contrast soils and Eucalypt on clay land types. It was demonstrated that the sites sampled were representative of their land types and that spatial bias of the photography, undetected tree-killing, sampling error, inherent variability of structural attributes and measurement error should not have impacted greatly on bias or precision of trend estimates for well-sampled land types. Certainly the errors are not likely to be substantial for trends averaged over all land types and they provide an accurate assessment of the magnitude and direction of change. The technique presented here would appear to be a robust means of accounting for the above-ground woody component of woodlands and open forests and will also contribute to a broader understanding of savanna dynamics.     

喷雾降尘在凡口铅锌矿的应用

介绍了喷雾降尘技术在凡口铅锌矿井下大斜坡道的应用情况，并对该技术进行了评价。     

烟气输运和水喷淋相互作用的大涡模拟研究

本文应用大涡模拟方法，并结合Smagorinsky亚格子尺度模型，数值研究了烟气输运和水喷淋的相互作用问题。为了有效地模拟烟气输运过程，文中采用低马赫数近似下的三维可压缩Navier-Stokes方程和组分方程进行求解，并采用有限差分法数值计算了滤波后的控制方程。对于燃烧过程扣所产生的热释放，采用Lagrangian粒子携带热量的近似方法来模拟，这些运动粒子进一步用来标识烟气的输运过程，同时还近似模拟了水喷淋和热气流的相互作用过程。文中数值计算了燃烧火源所形成的热气流和烟气输运过程，以及与水喷淋的相互作用，并探讨了喷水装置的喷水量、喷射角和水颗粒直径对流动特性的影响。     

速生杨木粉尘最小点火能的实验研究

为防止木材加工中木质粉尘燃爆事故的发生,以纤维板生产中常见的原材料速生杨木粉尘作为研究对象,在分析粉尘粒径分布、元素分析、工业分析及形貌特征的基础上,采用1.2 L哈特曼管对3种不同粒径（0~50,＞50~96,＞96~180 μm）速生杨木粉尘进行最小点火能实验,探究点火延迟时间、喷粉压力、质量浓度和粒径分布对速生杨木粉尘最小点火能的影响及变化规律。研究结果表明:在质量浓度为500 g/m3时,分别增加点火延迟时间和喷粉压力,最小点火能都先减小后增大;最佳点火延迟时间和最佳喷粉压力分别为120 ms和120 kPa;粒径对最佳点火延迟时间和最佳喷粉压力无显著影响。在点火延迟和喷粉压力分别为120 ms和120 kPa条件下,最小点火能随质量浓度的增加先减小后增大。粉尘粒径与最小点火能呈正相关性,3种样品的最小点火能分别为1~3,1~3和7~13 mJ,对应的敏感质量浓度分别为500 ,750和1 250 g/m3,属于特别着火敏感性粉尘。     

Pesticide distribution in an agricultural environment in Argentina

An assessment of the off-site migration of pesticides from agricultural activity into the environment in the Neuquen River Valley was performed. The aim of this study was to evaluate the distribution of pesticides in several compartments of a small agricultural sub-catchment. Soil, surface water, shallow groundwater and drift deposition were analyzed for pesticide residues. Results showed the presence of some pesticide residues in soil, surface water and shallow groundwater compartments. The highest detection frequencies in water (surface and subsurface) were found for azinphos-methyl and chlorpyrifos (>70%). In terms of concentration, the highest levels were observed in shallow groundwater for azinphos methyl (22.5 μg/L) and carbaryl (45.7 μg/L). In the soil, even before the application period had started, accumulation of residues was present. These residues increased during the period studied. Spray drift during pesticide application was found to be a significant pathway for the migration of pesticide residues in surface water, while leaching and preferential flows were the main transport routes contributing to subsurface contamination.