记忆中的邢台地震

当您翻开这一贞,南空中拍摄的地震火害区域图就映入了眼帘,40年前的往事浮现在脑海中……     

Upstream Addicks–Barker reservoir damages during Hurricane Harvey: A case study of urban hydrology and policy failure in Houston,TX

Addicks and Barker reservoirs were built in the 1940s to protect downtown Houston from flooding and have generally worked very well until 2017 when Hurricane Harvey devastated much of Houston and surroundings with up to 40 inches (102 cm) of rainfall causing flooding of 154,000 homes in over 22 watersheds in Houston/Harris County alone. However, the story of how Addicks and Barker flooded upstream residential areas from a hydrologic standpoint is a harsh lesson in flood infrastructure policy and funding. This failure to protect both downstream properties in Buffalo Bayou and upstream areas behind the dams ended up with tens of thousands of flooded homes and properties, with many having flood waters for over 10 days. This paper explores the main causes for the flooding and addresses the hydrologic issues upstream in both reservoirs. The main causes of flooding were not just related to a massive rainfall event, but also explosive urban expansion of land use upstream of reservoirs, altered and updated reservoir design issues, and lack of governmental action in the years leading up to the disaster. Potential long-term solutions to the flooding and design problems are addressed in this article as well.     

Near - Infrared Diode Laser Air Monitoring

Inexpensive near-infrared diode lasers are now being used to enable high sensitivity, real time monitoring of gases both in open path measurements of urban air quality and in industrial environments for stack gas emission monitoring. Individual species are detected in a highly selective manner via overtone and combination bands of their vibrational spectra. Operating at room temperature and with simple optical components they can be made into portable instruments, ideal for field measurements. Combined with optical fibres they can be used for accessing remote and possibly dangerous locations. This paper presents current progress on the development of such a system illustrating recent results on ammonia monitoring at 1540 nm and acetylene at 780 nm. Sensitivities of the order of parts per million and below have been attained. Advantages and disadvantages of this approach to air pollution monitoring will be described. Pressure broadening results are also given for the 2v1 band of ammonia.     

Comment on ‘Climate sensitivity,agricultural productivity and the social cost of carbon in FUND’

Environmental Economics and Policy Studies - Dayaratna et al. (Environ Econ Policy Stud 22:433–448, 2020) proposes several improvements to economic- and climate-simulating IAMs and to their...     

中国茶叶中的氟近十年来的研究进展

主要对茶叶中氟的来源,氟含量,氟浸出率以及茶叶降氟措施研究作了详细的综述。大量的研究资料表明,土壤中的氟直接影响到茶叶中氟的含量,茶树吸收氟与土壤的pH值、有机质含量、粘粒含量、成土母质及土壤中的阳离子有关。大气污染影响茶叶氟含量主要是氟通过叶片气孔进入细胞,进而在茶树体内积累。水环境中氟的含量主要受土壤与大气环境的影响。茶叶中的氟含量随着叶片成熟度的增加而增加;茶叶等级越差,氟含量越高;原料粗老的茶类氟含量要比原料较嫩的茶类氟含量高;不同季节、茶树品种对氟吸收也存在差异性;茶树各部位氟累积强度依次为:叶>花蕾>籽>皮>细枝>骨干枝>细根>茎(主轴)>茎(主干)>主根>侧根;茶叶中氟浸出率与冲泡水温、冲泡时间、冲泡次数等有关。在茶叶加工过程中可以通过热水处理,添加化学试剂,改进生产工艺等措施来降低茶叶中的氟含量。此外,尚可以培育含氟量低的茶树品种。     

Brazil’s Amazonian forest carbon: the key to Southern Amazonia’s significance for global climate

Southern Amazonia is the first region of Brazil’s Amazon area to be exposed to intensive conversion to agriculture and ranching. This conversion emits greenhouse gases from the carbon stock in the biomass and soils of the previous vegetation. Quantifying these carbon stocks is the first step in quantifying the impact on global warming from this conversion. This review is limited to information on Brazilian Amazonia’s carbon stocks. It indicates large amounts of carbon at risk of emission in both biomass and soils, as well as considerable uncertainty in estimates. Reducing uncertainty is a priority for research but the existence of uncertainty must not be used as an excuse for delaying measures to contain deforestation. The magnitude of carbon stocks is proportional to greenhouse gas emissions per hectare of deforestation and consequently to impact on global climate.

     

Measurement of particle concentrations in a dental office

Particles in a dental office can be generated by a number of instruments, such as air-turbine handpieces, low-speed handpieces, ultrasonic scalers, bicarbonate polishers, polishing cups, as well as drilling and air sprays inside the oral cavity. This study examined the generation of particles during dental drilling and measured particle size, mass, and trace elements. The air sampling techniques included both continuous and integrated methods. The following particle continuous measurements were taken every minute: (1) size-selective particle number concentration (Climet); (2) total particle number concentration (PTRAK), and; (3) particle mass concentration (DustTrak). Integrated particle samples were collected for about 5 h on each of five sampling days, using a PM_2.5 sampler (ChemComb) for elemental/organic carbon analysis, and a PM₁₀ sampler (Harvard Impactor) for mass and elemental analyses. There was strong evidence that these procedures result in particle concentrations above background. The dental procedures produced number concentrations of relatively small particles (<0.5 μm) that were much higher than concentrations produced for the relatively larger particles (>0.5 μm). Also, these dental procedures caused significant elevation above background of certain trace elements (measured by X-ray fluorescence) but did not cause any elevation of elemental carbon (measured by thermal optical reflectance). Dental drilling procedures aerosolize saliva and products of drilling, producing particles small enough to penetrate deep into the lungs. The potential health impacts of the exposure of dental personnel to such particles need to be evaluated. Increased ventilation and personal breathing protection could be used to minimize harmful effects.     

Potential negative consequences of adding phosphorus-based fertilizers to immobilize lead in soil

A study of the potential negative consequences of adding phosphate (P)-based fertilizers as amendments to immobilize lead (Pb) in contaminated soils was conducted. Lead-contaminated firing range soils also contained elevated concentrations of antimony (Sb), a common Pb hardening agent, and some arsenic (As) of unknown (possibly background) origin. After amending the soils with triple superphosphate, a relatively soluble P source, column leaching experiments revealed elevated concentrations of Sb, As, and Pb in the leachate, reflecting an initial spike in soluble Pb and a particularly dramatic increase in Sb and As mobility. Minimal As, Sb, and Pb leaching was observed during column tests performed on non-amended control soils. In vitro extractions tests were performed to assess changes in Pb, As, and Sb bioaccessibility on P amendment. Lead bioaccessibility was systematically lowered with increasing P dosage, but there was much less of an effect on As and Sb bioaccessibility than on mobility. Our results indicate that although P amendments may aid in lowering the bioaccessibility of soil-bound Pb, it may also produce an initial increase in Pb mobility and a significant release of Sb and As from the soil, dramatically increasing their mobility and to a lesser extent their bioavailability.     

Decreasing lead bioaccessibility in industrial and firing range soils with phosphate-based amendments

In-situ stabilization using phosphate (P) amendments, such as P-based fertilizers and rock, are a potentially cost-effective and minimally disruptive alternative for stabilizing Pb in soils. We examined the effect of time (0-365 d), in vitro extraction pH (1.5 vs. 2.3), and dosage of three P-based amendments on the bioaccessibility (as a surrogate for oral bioavailability) of Pb in 10 soils from U.S. Department of Defense facilities. Initial untreated soil bioaccessibility consistently exceeded the U.S. Environmental Protection Agency default value of 60% relative bioavailability, with higher bioaccessibility consistently observed at an in vitro extraction pH of 1.5 vs. 2.3. Although P-based amendments statistically (P < 0.05) reduced bioaccessibility in many instances, with reductions dependent on the amendment and dosage, large amendment dosages (approximately 20-25% by mass to yield 5% P by mass) were required to reduce average bioaccessibility by approximately 25%. For most amendment combinations, reductions continued to occur for periods up to 1 yr, indicating that the observed reductions were not merely experimental artifacts of the in vitro extraction procedure. Although our results indicated that reductions in Pb bioaccessibility with P amendments are technically feasible, relatively large amendment masses were required to achieve relatively modest reductions in bioaccessibility. The cost and potential environmental implications of adding such large amounts of P may limit the practicality of in situ immobilization for some Pb-contaminated soils, industrial and firing range soils in particular.     

Characteristics of coal mine ventilation air flows

Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. Underground coal mining is by far the most important source of fugitive methane emissions, and approximately 70% of all coal mining related methane is emitted to the atmosphere through mine ventilation air. Therefore, research and development on mine methane mitigation and utilisation now focuses on methane emitted from underground coal mines, in particular ventilation air methane (VAM) capture and utilisation. To date, most work has focused on the oxidation of very low concentration methane. These processes may be classified based on their combustion kinetic mechanisms into thermal oxidation and catalytic oxidation. VAM mitigation/utilisation technologies are generally divided into two basic categories: ancillary uses and principal uses. However, it is possible that the characteristics of ventilation air flows, for example the variations in methane concentration and the presence of certain compounds, which have not been reported so far, could make some potential VAM mitigation and utilisation technologies unfeasible if they cannot cope with the characteristics of mine site ventilation air flows. Therefore, it is important to understand the characteristics of mine ventilation air flows. Moreover, dust, hydrogen sulphide, sulphur dioxide, and other possible compounds emitted through mine ventilation air into the atmosphere are also pollutants. Therefore, this paper presents mine-site experimental results on the characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size, mineral matter of the dust, and other compounds in the ventilation air flows. The paper also discusses possible correlations between ventilation air characteristics and underground mining activities.