Measurement errors in spawner abundance create problems for fish stock assessment scientists. To deal with measurement error, we develop a Bayesian state-space model for stock-recruitment data that contain measurement error in spawner abundance, process error in recruitment, and time series bias. Through extensive simulations across numerous scenarios, we compare the statistical performance of the Bayesian state-space model with that of standard regression for a traditional stock-recruitment model that only considers process error. Performance varies depending on the information content in data, as determined by stock productivity, types of harvest situations, and amount of measurement error. Overall, in terms of estimating optimal spawner abundance SMSY, the Ricker density-dependence parameter β, and optimal harvest rate hMSY, the Bayesian state-space model works best for informative data from low and variable harvest rate situations for high-productivity salmon stocks. The traditional stock-recruitment model (TSR) may be used for estimating α and hMSY for low-productivity stocks from variable and high harvest rate situations. However, TSR can severely overestimate SMSY when spawner abundance is measured with large error in low and variable harvest rate situations. We also found that there is substantial merit in using hMSY (or benchmarks derived from it) instead of SMSY as a management target. 相似文献
Recently, a typical semi-automatic recycling line is proved to be a feasible method for resource recovery of raw material of waste CRTs. However, there are no relevant studies about health risk assessment of the particles and heavy metals diffused from this physical recycling process for CRTs. In this study, TSP, PM10 and heavy metals (Cr, Ni, Cu, Zn, Cd and Pb) in the ambience of the workshop have been evaluated. The mean concentrations of TSP and PM10 in the workshop were 481.5 and 316.9 μg/m3, respectively. Meanwhile, it can be seen that Zn (8.1 and 7.9 μg/m3, respectively) was the most enriched metal in TSP and PM10, followed by Pb (3.2 and 3.0 μg/m3, respectively). Health risk assessment showed that the total hazard index was 3.29, exceeding the danger threshold. The health risk of different metals was Cr > Cd > Ni. In short, the research results show that mechanical–physical process for e-waste recycling do exist the pollutant mission. So the effective measures should be taken to reduce the harm of pollutants on the workers’ health. 相似文献
Bioreactive thin-layer capping (BTC) with biozeolite provides a potential remediation design that can sustainably treat N contamination from sediment and overlying water in eutrophic water bodies. Nitrogen (N) reduction using BTC with biozeolite was examined in a field incubation experiment in a eutrophic river in Yangzhou, Jiangsu Province, China. The biozeolite was zeolite with attached bacteria, including two isolated heterotrophic nitrifiers (Bacillus spp.) and two isolated aerobic denitrifiers (Acinetobacter spp.). The results showed that the total nitrogen (TN) reduction efficiency of the overlying water by BTC with biozeolite (with thickness of about 2 mm) reached a maximum (56.69%) at day 34, and simultaneous heterotrophic nitrification and aerobic denitrification occurred in the BTC system until day 34. There was a significant difference in the TN concentrations of the overlying water between biozeolite capping and control (t-test; p < 0.05). The biozeolite had very strong in situ bioregeneration ability. Carbon was the main source of nitrifier growth. However, both dissolved oxygen (DO) and carbon concentrations affected denitrifier growth. In particular, DO concentrations greater than 3 mg/L inhibited denitrifier growth. Therefore, BTC with biozeolite was found to be a feasible technique to reduce N in a eutrophic river. However, it is necessary to further strengthen the adaptability of aerobic denitrifiers through changing domestication methods or conditions. 相似文献
Photocatalytic technology has been widely studied by researchers in the field of environmental purification. This technology can not only completely convert organic pollutants into small molecules of CO2 and H2O through redox reactions but also remove metal ions and other inorganic substances from water. This article reviews the research progress of graphene-based photocatalytic nanocomposites in the treatment of wastewater. First, we elucidate the basic principles of photocatalysis, the types of graphene-based nanocomposites, and the role of graphene in photocatalysis (e.g., graphene can accelerate the separation of photon-hole pairs and increase the intensity and range of light absorption). Second, the preparation, characterization, and application of composites in wastewater are introduced. We also discuss the kinetic model of the photocatalytic degradation of pollutants. Finally, the enhancement mechanism of graphene in terms of photocatalysis is not completely clear, and graphene-based photocatalysts with high catalytic efficiency, low cost, and large-scale production have not yet appeared, so there is an urgent need for more extensive and in-depth research.
● The co-existing metals in WPCBs has positive catalytic influence in pyrolysis. ● Cu, Fe, Ni can promote reaction progress and reduce the apparent activation energy. ● Ni play better role in promoting WPCB pyrolysis reaction. Waste printed circuit boards (WPCBs) are generated increasingly recent years with the rapid replacement of electric and electronic products. Pyrolysis is considered to be a potential environmentally-friendly technology for recovering organic and metal resources from WPCBs. Thermogravimetric analysis and kinetic analysis of WPCBs were carried out in this study. It showed that the co-existing metals (Cu, Fe, Ni) in WPCBs have positive self-catalytic influence during the pyrolysis process. To illustrate their catalytic effects, the apparent activation energy was calculated by differential model. Contributions of different reactions during catalytic pyrolysis process was studied and the mechanism function was obtained by Šesták-Berggren model. The results showed that Cu, Fe, Ni can promote the reaction progress and reduce the apparent activation energy. Among the three metals, Ni plays better catalytic role than Cu, then Fe. This work provides theoretical base for understanding the three metals’ catalytic influence during the pyrolysis of non-metal powders in WPCBs. 相似文献
Journal of Material Cycles and Waste Management - An electrical low-pressure impactor was used to measure the particulate matter (PM) characteristics in a formal e-waste recycling plant. The size... 相似文献