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81.
James C. Hower Jennifer M.K. O'Keefe Kevin R. Henke Amirhossein Bagherieh 《International Journal of Coal Geology》2011,88(4):227
Coal fires in natural outcrops, in abandoned and active coal mines, and in coal and coal-refuse piles are responsible for the uncontrolled emissions of gases, including CO, CO2, H2S, hydrocarbons, and volatile aromatics. Typically, measurements of gases at a mine vent are made over a short time interval, perhaps no more than 10 min, including the time for replicate measurements. Such timing provides little information on longer-term variations in emissions, although comparisons of seasonal measurements suggest such changes do occur. To address this problem, we placed temperature and CO data loggers in coal fire vents to collect time series measurements for a period of up to three weeks. For one experiment, 11 days of data at one-minute intervals indicated that the CO emissions were generally in the 400–550 ppmv range. However near daily depressions in CO concentrations occurred and in some cases fell below 50 ppmv; followed by an increase to ~ 700–800 ppmv; in turn followed by a return to the ambient conditions. Data for a separate 21-day collection period in a different vent of the same fire exhibited similar trends, albeit at a higher CO concentration. The drop in CO concentration may be associated with a meteorologically-driven inhalation cycle of the fire, whereby air diluted the combustion generated CO. We propose this was followed by an increase in the intensity of the fire due to increased O2 from the inhaled air, producing increased CO concentrations, before settling back to the ambient conditions. 相似文献
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万山群岛海域生态环境日益恶化、渔业资源持续衰退,因此建设万山群岛海洋牧场,修复海域生态环境、实现渔业资源可持续利用迫在眉睫。针对现阶段基于海洋生物资源的海洋牧场适宜性评估的研究较少,本研究利用渔业资源调查和全球物种数据库记录数据及13个环境因素数据,采用物种分布模型MaxEnt对选择的白姑鱼、日本金线鱼、红星梭子蟹和浅缝骨螺潜在分布区进行预测,探讨海洋生物地理分布与海洋环境因素之间的关系进而进行万山海洋牧场生境适宜性评估,结果表明:(1)各模型AUC值均大于0.9,说明构建的模型对这些物种潜在分布的模拟效果较好,后续可采用MaxEnt模型对4种生物的栖息地分布区进行预测;(2)海底浮游植物密度、海底温度以及海底硅酸盐浓度是影响这4种海洋生物栖息地分布的关键环境因子;(3)基于该4种海洋物种MaxEnt模型的HSI分布区所存在重叠区域来看,海洋牧场拟建设区域应为纬度21.85°N~22.15°N,经度113.6°E~114.2°E。研究结果可为万山海洋牧场规划和建设提供科学依据。 相似文献
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The rapid and high bioaccumulation of mercury in marine mammals and its spatial and temporal variations have been a major puzzle in the Arctic. While extensive efforts have been focussed on the monitoring and chemistry of atmospheric mercury depletion events, a recent mass budget estimate of mercury in the Arctic suggests that we have overlooked the role of the ocean itself. Only through focussed studies on Hg dynamics in the Arctic Ocean under a changing climate are we going to understand what the risk of mercury is to those marine ecosystems and the people who rely on them. 相似文献
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Distribution and speciation of mercury in surficial sediments from main mangrove wetlands in China 总被引:4,自引:0,他引:4
The purpose of this study was to establish the distribution, speciation and bioavailability of mercury in mangrove sediments. A systemic survey of surficial sediments from 13 mangrove wetlands of China was carried out. Hg concentrations ranged from 2.3–903.6 ng g−1, with an average value of 189.4 ng g−1. Of the 13 areas surveyed, the Hg content in sediments was similar to background levels in 6 areas but was much higher in the other seven areas. Hg levels were affected by natural and anthropogenic factors, including terrestrial pollutants, geomorphic properties, and indirectly by economic status. Hg levels were positively correlated with organic matter, pH, and silt and clay fractions, but Hg was negatively correlated with sand fraction. In most mangrove wetlands, Hg existed primarily in the form of volatile Hg. Hg is easily bioaccumulated in mangrove wetlands and may be the natural source of Hg emissions to the atmosphere. 相似文献
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珠海万山群岛海上生态公园建设规划构想 总被引:2,自引:0,他引:2
万册群岛位于珠江口门,拥有优越的区位条件,理想的旅游气候,众多的岛屿,广阔的海域,丰富的生物和旅游资源,发展海上生态旅游大有可为。根据珠海市旅游发展战略定位-国际旅游度假会议会展城,认为万山群岛是实施这一战略的重要组成部分,提出建设“万山群岛海上生态公园”的规划构想和若干建议。 相似文献
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The abandoned Hg mine in Podljubelj was in operation with interceptions from 1557 to 1902. The entire operating period yielded about 110 000 tons of ore, from which 360 tons of Hg was produced. The objective of the research project was to establish the contents and spatial distribution of Hg in soils and stream sediments in the vicinity of the mine. On an area of 88 ha the soil was sampled in a 100 × 100 m grid. Two soil horizons (0–5 cm and 20–30 cm) were sampled in order to distinguish between geogenic and anthropogenic Hg sources. It was established that on an area of about 9 ha Hg content in soil exceeds The New Dutchlist action value for Hg (10 mg/kg). Total Hg concentrations in soil samples vary between 0.17 and 719 mg/kg, with a mean of 3.0 mg/kg. Mercury contents in stream sediments range from 0.065 to 1.4 mg/kg, with a mean of 0.64 mg/kg. The highest determined value in soils was found in the area around the former roasting furnace, where the ore was processed. Increased Hg concentrations were also found on the mine waste dump (108 mg/kg). Mercury contents in soils generally decrease with soil profile depth and with the distance from the mine and from the roasting furnace location. Mercury also appears in higher concentrations along the road that runs through the valley, which results from the use of Hg-bearing ore residues in road construction. The average enrichment factor (EF) of Hg in topsoil with respect to subsoil is 3.3. Calculated enrichment factors show higher values also for Cd (3.2), Pb (2.7), Ca (2.4) and P (1.9). The average enrichment factor of Hg in topsoil with regard to the established Slovenian soil averages (EFslo) is 19. EFslo of other determined chemical elements do not exceed 3.0. 相似文献