Al2O3为载体的催化剂净化贫燃汽车尾气研究

在富氧条件下,考察了C₃H₆和C₂H₅OH在Ag/Al₂O₃、In/Al₂O₃、Sn/Al₂O₃、Co/Al₂O₃、Pt/Al₂O₃和Ag/Al₂O₃+Pt/Al₂O₃组合催化剂上选择性还原NO的性能.结果表明,Ag/Al₂O₃具有最高的NO还原活性.在负载型过渡金属氧化物催化剂上,会生成显著量的CO,其HC和CO氧化转化温度也远远高于Pt/Al₂O₃催化剂.串联组合Ag/Al₂O₃+Pt/Al₂O₃催化剂可显著拓宽活性温度范围,促进HC和CO氧化,降低N₂O和CH₃CHO生成量.     

吊水壶尾矿坝渗流特性三维有限元分析

本文结合工程实例,以吊水壶尾矿坝为背景,建立现状尾矿坝三维模型,利用三维有限元法反演分析现状尾矿坝的渗流场,将计算结果与勘察的浸润面对比分析,验证模型的可靠性和合理性。基于此模型建立加高后的尾矿坝三维模型,计算正常蓄水位和设计洪水位两种工况下的渗流场,分析坝体浸润面埋深、滩长、渗流坡降等,结果表明,不设排渗措施时,尾矿坝干滩长度、浸润面埋深均能满足规范要求,而且尖流性态良好,满足渗透稳定。提出该尾矿坎可通过加高工程来进行渗流控制的建议。     

Environmental awareness and biodiversity conservation among resettled communal farmers in Gwayi Valley Conservation Area,Zimbabwe

This study was conducted in Gwayi Valley Conservation Area in Zimbabwe. The objective was to evaluate the level of environmental awareness raising among rural communities resettled by government in a wildlife conservation area and their behavior and actions towards biodiversity conservation. We selected three communities based on the degree of exposure to environmental awareness campaigns by various government departments and non-governmental organizations. This formed a gradient of exposure to environmental awareness campaigns, ranging from the most accessible and exposed community (Hangano), moderately exposed (Gwayi) through to the least accessible and exposed community (Karna). We used focus group discussions, key informant interviews and structured interviews with 95 respondents in the selected communities from November 2016 to April 2017. Through public awareness raising, a number of conservation groups were established including fire and hunting committees, anti-poaching teams and environmental resource monitors. While these groups were found to be either inactive or less effective in Gwayi and Karna, all were found to be very active and effective in Hangano. Similarly, community behavior and actions that caused biodiversity loss such as indiscriminate cutting of live trees, poaching, streambank cultivation, fishing in rivers with nets and use of sledges were much reduced in Hangano than in Gwayi and Karna. Frequent environmental awareness campaigns played a critical role in promoting biodiversity in Hangano. We conclude that substantial gains can be made in environmental conservation by investing more in public awareness campaigns, particularly in developing countries such as Zimbabwe where financial resources for conservation are scarce.     

Impacts of emissions and meteorological changes on China’s ozone pollution in the warm seasons of 2013 and 2017

O₃ increment is mainly caused by changes in meteorology rather than emissions. Emission reduction is effective to reduce O₃ nationwide, especially in summer. Strengthened NO_x controls are necessary to meet the ambient O₃ standard. We have quantified the impacts of anthropogenic emissions reductions caused by the Air Pollution Control Action Plan and changes in meteorological fields between 2013 and 2017 on the warm-season O₃ concentration in China using a regional 3D chemical transport model. We found that the impact on daily maximum eight-hour (MDA8) O₃ concentration by the meteorological variation that mostly increased O₃ was greater than that from emission reduction, which decreased O₃. Specifically, the control measures implemented since 2013 in China have reduced SO₂, NO_x, PM_2.5, and VOC emissions by 33%, 25%, 30%, and 4% in 2017, while NH₃ emissions have increased by 7%. The changes in anthropogenic emissions lowered MDA8 O₃ by 0.4–3.7 ppb (0.8%–7.6%, varying by region and month), although MDA8 O₃ was increased slightly in some urban areas (i.e. North China) at the beginning/end of warm seasons. Relative to 2013, the average 2 m temperature in 2017 shows increments in North, North-east, East, and South China (0.34℃–0.83℃) and decreases in Central China (0.24℃). The average solar radiation shows increments in North, North-east, and South China (7.0–9.7 w/m²) and decreases in Central, South-west, and North-west China (4.7–10.3 w/m²). The meteorological differences significantly change MDA8 O₃ by -3.5–8.5 ppb (-8.2%–18.8%) with large temporal variations. The average MDA8 O₃ was slightly increased in North, North-east, East, and South China. The response surface model suggests that the O₃ formation regime transfers from NO_x-saturated in April to NO_x-limited in July on average in China.     

Minimizing opportunity costs to aquatic connectivity restoration while controlling an invasive species

Controlling invasive species is critical for conservation but can have unintended consequences for native species and divert resources away from other efforts. This dilemma occurs on a grand scale in the North American Great Lakes, where dams and culverts block tributary access to habitat of desirable fish species and are a lynchpin of long‐standing efforts to limit ecological damage inflicted by the invasive, parasitic sea lamprey (Petromyzon marinus). Habitat restoration and sea‐lamprey control create conflicting goals for managing aging infrastructure. We used optimization to minimize opportunity costs of habitat gains for 37 desirable migratory fishes that arose from restricting sea lamprey access (0–25% increase) when selecting barriers for removal under a limited budget (US$1–105 million). Imposing limits on sea lamprey habitat reduced gains in tributary access for desirable species by 15–50% relative to an unconstrained scenario. Additional investment to offset the effect of limiting sea‐lamprey access resulted in high opportunity costs for 30 of 37 species (e.g., an additional US$20–80 million for lake sturgeon [Acipenser fulvescens]) and often required ≥5% increase in sea‐lamprey access to identify barrier‐removal solutions adhering to the budget and limiting access. Narrowly distributed species exhibited the highest opportunity costs but benefited more at less cost when small increases in sea‐lamprey access were allowed. Our results illustrate the value of optimization in limiting opportunity costs when balancing invasion control against restoration benefits for diverse desirable species. Such trade‐off analyses are essential to the restoration of connectivity within fragmented rivers without unleashing invaders.     

Countering resistance to protected‐area extension

The establishment of protected areas is a critical strategy for conserving biodiversity. Key policy directives like the Aichi targets seek to expand protected areas to 17% of Earth's land surface, with calls by some conservation biologists for much more. However, in places such as the United States, Germany, and Australia, attempts to increase protected areas are meeting strong resistance from communities, industry groups, and governments. We examined case studies of such resistance in Victoria, Australia, Bavaria, Germany, and Florida, United States. We considered 4 ways to tackle this problem. First, broaden the case for protected areas beyond nature conservation to include economic, human health, and other benefits, and translate these into a persuasive business case for protected areas. Second, better communicate the conservation values of protected areas. This should include highlighting how many species, communities, and ecosystems have been conserved by protected areas and the counterfactual (i.e., what would have been lost without protected area establishment). Third, consider zoning of activities to ensure the maintenance of effective management. Finally, remind citizens to think about conservation when they vote, including holding politicians accountable for their environmental promises. Without tackling resistance to expanding the protected estate, it will be impossible to reach conservation targets, and this will undermine attempts to stem the global extinction crisis.     

Factors influencing property selection for conservation revolving funds

Finding sustainable ways to increase the amount of private land protected for biodiversity is challenging for many conservation organizations. In some countries, organizations use revolving‐fund programs, whereby land is purchased and then sold to conservation‐minded owners under condition they enter into a conservation covenant or easement. The sale proceeds are used to purchase, protect, and sell additional properties, incrementally increasing the amount of protected private land. Because the effectiveness of this approach relies on selecting appropriate properties, we explored factors currently considered by practitioners and how these are integrated into decision making. We conducted exploratory, semistructured interviews with managers from each of the 5 major revolving funds in Australia. Responses indicated although conservation factors are important, financial and social factors are also highly influential. A major determinant was whether the property could be resold within a reasonable period at a price that replenishes the fund. To facilitate resale, often selected properties include the potential for the construction of a dwelling. Practitioners face with clear trade‐offs between conservation, financial, amenity, and other factors in selecting properties and 3 main challenges: recovering the costs of acquisition, protection, and resale; reselling the property; and meeting conservation goals. Our findings suggest the complexity of these decisions may constrain revolving‐fund effectiveness. Drawing from participant responses, we identified potential strategies to mitigate these risks, such as providing adequate recreational space without jeopardizing ecological assets. We suggest managers could benefit from a shared‐learning and adaptive approach to property selection given the commonalities between programs. Understanding how practitioners deal with complex decisions in the implementation of revolving funds helps identify future research to improve the performance of this conservation tool.     

The potential for biodiversity offsetting to fund effective invasive species control

Compensating for biodiversity losses in 1 location by conserving or restoring biodiversity elsewhere (i.e., biodiversity offsetting) is being used increasingly to compensate for biodiversity losses resulting from development. We considered whether a form of biodiversity offsetting, enhancement offsetting (i.e., enhancing the quality of degraded natural habitats through intensive ecological management), can realistically secure additional funding to control biological invaders at a scale and duration that results in enhanced biodiversity outcomes. We suggest that biodiversity offsetting has the potential to enhance biodiversity values through funding of invasive species control, but it needs to meet 7 key conditions: be technically possible to reduce invasive species to levels that enhance native biodiversity; be affordable; be sufficiently large to compensate for the impact; be adaptable to accommodate new strategic and tactical developments while not compromising biodiversity outcomes; acknowledge uncertainties associated with managing pests; be based on an explicit risk assessment that identifies the cost of not achieving target outcomes; and include financial mechanisms to provide for in‐perpetuity funding. The challenge then for conservation practitioners, advocates, and policy makers is to develop frameworks that allow for durable and effective partnerships with developers to realize the full potential of enhancement offsets, which will require a shift away from traditional preservation‐focused approaches to biodiversity management. El Potencial de la Compensación de la Biodiversidad para Financiar Controles Efectivos de Especies Invasoras     

Estimating the normal background rate of species extinction

A key measure of humanity's global impact is by how much it has increased species extinction rates. Familiar statements are that these are 100–1000 times pre‐human or background extinction levels. Estimating recent rates is straightforward, but establishing a background rate for comparison is not. Previous researchers chose an approximate benchmark of 1 extinction per million species per year (E/MSY). We explored disparate lines of evidence that suggest a substantially lower estimate. Fossil data yield direct estimates of extinction rates, but they are temporally coarse, mostly limited to marine hard‐bodied taxa, and generally involve genera not species. Based on these data, typical background loss is 0.01 genera per million genera per year. Molecular phylogenies are available for more taxa and ecosystems, but it is debated whether they can be used to estimate separately speciation and extinction rates. We selected data to address known concerns and used them to determine median extinction estimates from statistical distributions of probable values for terrestrial plants and animals. We then created simulations to explore effects of violating model assumptions. Finally, we compiled estimates of diversification—the difference between speciation and extinction rates for different taxa. Median estimates of extinction rates ranged from 0.023 to 0.135 E/MSY. Simulation results suggested over‐ and under‐estimation of extinction from individual phylogenies partially canceled each other out when large sets of phylogenies were analyzed. There was no evidence for recent and widespread pre‐human overall declines in diversity. This implies that average extinction rates are less than average diversification rates. Median diversification rates were 0.05–0.2 new species per million species per year. On the basis of these results, we concluded that typical rates of background extinction may be closer to 0.1 E/MSY. Thus, current extinction rates are 1,000 times higher than natural background rates of extinction and future rates are likely to be 10,000 times higher. Estimación de la Tasa Normal de Extinción de Especies     

Impact of conservation areas on trophic interactions between apex predators and herbivores on coral reefs

Apex predators are declining at alarming rates due to exploitation by humans, but we have yet to fully discern the impacts of apex predator loss on ecosystem function. In a management context, it is critically important to clarify the role apex predators play in structuring populations of lower trophic levels. Thus, we examined the top‐down influence of reef sharks (an apex predator on coral reefs) and mesopredators on large‐bodied herbivores. We measured the abundance, size structure, and biomass of apex predators, mesopredators, and herbivores across fished, no‐take, and no‐entry management zones in the Great Barrier Reef Marine Park, Australia. Shark abundance and mesopredator size and biomass were higher in no‐entry zones than in fished and no‐take zones, which indicates the viability of strictly enforced human exclusion areas as tools for the conservation of predator communities. Changes in predator populations due to protection in no‐entry zones did not have a discernible influence on the density, size, or biomass of different functional groups of herbivorous fishes. The lack of a relationship between predators and herbivores suggests that top‐down forces may not play a strong role in regulating large‐bodied herbivorous coral reef fish populations. Given this inconsistency with traditional ecological theories of trophic cascades, trophic structures on coral reefs may need to be reassessed to enable the establishment of appropriate and effective management regimes. El Impacto de las Áreas de Conservación sobre las Interacciones Tróficas entre los Depredadores Dominantes y los Herbívoros en los Arrecifes de Coral