Consumption and production waste: another externality of tobacco use

OBJECTIVE: To describe the waste produced by and environmental implications of individual cigarette consumption (filter tips, packages, and cartons) and tobacco manufacturing. STUDY SELECTION: All available articles and reports published since 1970 related to cigarette consumption and production waste were reviewed. DATA SOURCES: Global cigarette consumption data were used to estimate cigarette butt and packaging waste quantities. Data from the Center for Marine Conservation's International Coastal Cleanup Project were used to describe some environmental impacts of tobacco-related trash. Data from the United States Environmental Protection Agency's (EPA's) Toxics Release Inventory and reported global cigarette consumption totals were used to estimate waste production from cigarette manufacturing. DATA EXTRACTION AND SYNTHESIS: In 1995, an estimated 5.535 trillion cigarettes (27,675 million cartons and 276,753 million packages) were sold by the tobacco industry globally. Some of the wastes from these products were properly deposited, but a large amount of tobacco consumption waste ends up in the environment. Some is recovered during environmental clean-up days. For the past eight years (1990-1997), cigarette butts have been the leading item found during the International Coastal Cleanup Project; they accounted for 19.1% of all items collected in 1997. The tobacco manufacturing process produces liquid, solid, and airborne waste. Among those wastes, some materials, including nicotine, are designated by the EPA as Toxics Release Inventory (TRI) chemicals. These are possible environmental health hazards. In 1995, the global tobacco industry produced an estimated 2262 million kilograms of manufacturing waste and 209 million kilograms of chemical waste. In addition, total nicotine waste produced in the manufacture of reduced nicotine cigarettes was estimated at 300 million kilograms. CONCLUSIONS: Laws against littering relative to cigarette butts could be better enforced. Additional taxes might be levied on cigarette products that would then be directed to environmental clean-up efforts. The tobacco industry should improve the biodegradability of filters, reduce packaging waste, and educate its customers. Worksites and public buildings should be encouraged or required to supply appropriate disposal mechanisms at all building entrances. Public awareness campaigns about the magnitude and prevention of cigarette consumption waste could be developed through partnerships among environmental groups, health organisations, and environmental protection agencies. Tobacco production waste should be a source of concern and regulation by governments throughout the world; it contains numerous chemicals which may be considered health hazards, not the least of which is nicotine produced in the manufacture of low-nicotine cigarettes.     

Monoterpene concentrations in fresh,senescent, and decaying foliage of singleleaf pinyon (Pinus monophylla Torr. & Frem.: Pinaceae) from the western Great Basin

Senescent foliage from pines is potentially a large contributor to the total monoterpene content of the litter layer, and the availability of these compounds as phytotoxins may result from release of these compounds into the vapor phase. In order to determine the fate of several monoterpene hydrocarbons in the natural environment, we examined their concentrations in fresh, senescent, and decaying needles from 32 single-leaf pinyon pine (Pinus monophylla Torr. & Frem.: Pinaceae) trees growing at two different locations. Total monoterpene content was highest in the fresh needles (mean=5.6 ± 2.2 mg/g extracted air dry weight), but also remained relatively high in senescent needles (mean=3.6 ±1.8 mg/g extracted air dry weight), either still attached to the tree or forming the freshest layer of understory litter. Decaying needles within a dark decomposing layer of litter material 5–20 cm from the surface were found to contain much lower amounts of total monoterpenes (average: =0.12 ±0.06 mg/g extracted air dry weight). Further investigation of the fate of these compounds in the pinyon understory is required to determine if these hydrocarbons are indeed exerting phytotoxic characteristics.     

Combustion of poultry-derived fuel in a coal-fired pilot-scale circulating fluidized bed combustor

Poultry farming generates large quantities of waste. The current practice is to spread this waste onto farmland as fertilizer. However, as the factory farms for poultry grow both in numbers and size, the amount of waste generated has increased significantly in recent years. In consequence, excessive application of poultry wastes on farmland is resulting in more and more nutrients entering the surface water. One of the options being considered is the use of poultry waste as power plant fuel. Since poultry-derived fuel (PDF) is biomass, its co-firing will have the added advantage of reducing greenhouse gas emissions from power generation. To evaluate the combustion characteristics of co-firing PDF with coal, combustion tests were conducted in CanmetENERGY's pilot-scale circulating fluidized bed combustor (CFBC). The goal of this program was to verify that PDF can be co-fired with coal and, more importantly, that emissions from the combustion process are not adversely affected by the presence of PDF in the feed. The test results were very promising and support the idea that co-firing in an existing CFBC boiler firing coal is a good way to utilize PDF, resolving a potential waste disposal problem while reducing the amount of CO₂ released from the boiler.     

Effects of Elevated CO<Subscript>2</Subscript> and Herbivore Damage on Litter Quality in a Scrub Oak Ecosystem

Atmospheric CO₂ concentrations have increased dramatically over the last century and continuing increases are expected to have significant, though currently unpredictable, effects on ecosystems. One important process that may be affected by elevated CO₂ is leaf litter decomposition. We investigated the interactions among atmospheric CO₂, herbivory, and litter quality within a scrub oak community at the Kennedy Space Center, Florida. Leaf litter chemistry in 16 plots of open-top chambers was followed for 3 years; eight were exposed to ambient levels of CO₂, and eight were exposed to elevated levels of CO₂ (ambient + 350 ppmV). We focused on three dominant oak species, Quercus geminata, Quercus myrtifolia, and Quercus chapmanii. Condensed tannin concentrations in oak leaf litter were higher under elevated CO₂. Litter chemistry differed among all plant species except for condensed tannins. Phenolic concentrations were lower, whereas lignin concentrations and lignin/nitrogen ratios were higher in herbivore-damaged litter independent of CO₂ concentration. However, changes in litter chemistry from year to year were far larger than effects of CO₂ or insect damage, suggesting that these may have only minor effects on litter decomposition.     

Nitrogen budget for fescue pastures fertilized with broiler litter in Major Land Resource Areas of the southeastern US

The southeast US produces a tremendous number of broiler chickens (Gallus gallus), which in turn produce massive quantities of litter (manure and bedding materials). In the Southeast, litter is most often disposed of via land application to pastures, however, the ultimate fate of much of the applied nitrogen (N) is not known. We have constructed N budgets for three sites across the southeastern U.S. in an effort to determine how much of the applied N is useful for plant production and how much is left to be absorbed by the environment. Study sites were located in the Coastal Plain (Alabama), Piedmont (Georgia), and Cumberland Plateau (Tennessee) Major Land Resource Areas (MLRA) of the southeastern US. Litter was applied in the Spring of two consecutive years at a rate to supply 70 kg of available N ha^–1. The total amount of N applied ranged from 103 to 252 kg N ha^–1 depending on site and year. Nitrogen fluxes monitored in this study were broiler litter N, ammonia (NH₃) volatilization, denitrification, plant uptake, and leaching. Plant uptake represented the largest flux of applied N, averaging 43% of applied N. Losses due to NH₃ volatilization and denitrification combined were only 6% of applied N on average. Loss of N due to NO₃-N leaching appeared to be significant only at the Coastal Plain site where NO₃-N concentrations in the groundwater peaked at 38 mg N l^–1. We believe the majority of excess N shown in these budgets is likely accounted for by leaching losses and soil accumulation. Regardless of these assumptions and low gaseous losses, it is apparent that on average, 57% of applied N is destined for a fate other than plant uptake. The results of this study indicate that land-application of broiler litter at currently recommended rates has the potential for negative impacts on the environment of the southeastern U.S. in the long-term.     

红松林地表凋落物层燃烧数值模拟

采用PyroSim建立红松林地表凋落物层大空间模型,对凋落物层的燃烧温度、热释放速率、烟气浓度等进行数值模拟。取红松林地表凋落物进行试验,探究其燃烧与蔓延过程。结果表明,红松林地表凋落物层燃烧时温度在100～490 ℃;随着高度增加,温度下降幅度由剧烈逐渐趋于平缓;燃烧150 s时,热释放速率HRR达到7.5×105 kW,且有继续上升趋势;燃烧烟气中CO2体积分数达8％～10％;火场内流动风速为2 m/s时,烟气体积分数下降65％左右。凋落物燃烧温度曲线与模拟结果相似,采用PyroSim软件能够近似地模拟红松林地表凋落物层燃烧的过程与发展趋势。     

电梯不同负载下的功能设置

围绕电梯负载时的功能设置命令编制 ,针对电梯不同负载情况设定相应的功能 ,使电梯的运行更加科学、合理、有效。     

YOLOESD-基于改进YOLOv8的海洋垃圾图像检测

海洋垃圾不仅严重威胁海洋动物的健康及其栖息地,由其释放的有毒物质进入食物链后对人类身体健康同样造成消极影响。由于海洋图像受到光照投影的影响,并且垃圾的尺寸通常较小,以往的目标检测算法对海洋垃圾的检测性能并不理想,因此提出了一种基于YOLOv8网络模型的改进算法(YOLOESD),该算法共有三个改进点：首先,采用Stemblock模块替换了模型的初始卷积,在减少模型参数量的同时,提高模型检测的精确度;其次,融合高效多尺度注意力模块(EMA),有效减少了模型的漏检和误检问题;最后,在原模型的头部额外增加一个小目标检测头,提高模型对小尺度目标的敏感度。实验结果表明,改进后的YOLOv8网络模型与原网络模型相比,漏检情况得到明显改善,mAP@0.5达到90.8%,精度提高了3.6个百分点;YOLOESD网络模型的检测效果优于原网络模型及经典的网络模型。