附加环境因素:传统比较优势理论的扩展

在李嘉圈模型中，若将环境成本用追加的劳动投入来衡量。可以发现，环境成本的引入将修正传统的比较优势格局。在H-O模型中耐加环境因素，亦即假定环境作为一种生产要搴而起作用。则所形成的比较优势将建立在包含环境要素真实价格的基础之上。本文最后指出，环境要素的真实价格与现实价格的脱离，使“显示的比较优势”有可能与真实的比较优势发生偏离。从而损害效率与公平。     

Time discounting and the decision to protect areas that are near and threatened or remote and cheap to acquire

Should conservation organizations focus on protecting habitats that are at imminent risk of being converted but are expensive or more remote areas that are less immediately threatened but where a large amount of land can be set aside? Variants of this trade‐off commonly arise in spatial planning. I used models of land‐use change near a deforestation frontier to examine this trade‐off. The optimal choice of where to protect was determined by how decisions taken today accounted for ecological benefits and economic costs of conservation actions that would occur sometime in the future. I used an ecological and economic discount rate to weight these benefits and costs. A large economic discount rate favored protecting more remote areas, whereas a large, positive ecological discount rate favored protecting habitat near the current deforestation frontier. The decision over where to protect was also affected by the influence economic factors had on landowners' decisions, the rate of technological change, and ecological heterogeneity of the landscape. How benefits and costs through time are accounted for warrants careful consideration when specifying conservation objectives. It may provide a niche axis along which conservation organizations differentiate themselves when competing for donor funding or other support.     

Synthesis of Poly(β-hydroxybutyrate) in Simulated Microgravity: An Investigation of Aeration Profiles in Shake Flask and Bioreactor

The microbial strain Azotobacter vinelandii UWD was grown under conditions of simulated microgravity in the National Aeronautics and Space Administration (NASA) Bioreactor. Bacterial growth in simulated microgravity differed significantly from that observed in conventional shake flask experiments: Cells tended to grow in a cluster-like pattern and polymer production started immediately after exposing them to conditions of simulated microgravity, and no lag time was observed. It was imperative to differentiate between the effects derived from microgravity and those imposed by the altered oxygen supply in the bioreactor. Aeration conditions were studied in both reactor types and a gas supply profile was developed for the bioreactor. This supply profile allowed for similar amounts of dissolved oxygen in the bioreactor and the shake flask in the initial stage of the fermentation and, therefore, for an evaluation of the effects of microgravity on biopolyester-producing bacteria. Since the optical density that is conventionally used as a measure for the cell growth could not be used due to the cluster-like growth pattern of the cells, it was determined that bacterial growth behavior in the bioreactor can be monitored through glucose or oxygen consumption.     

Preliminary Studies on Converting Agricultural Waste into Biodegradable Plastics,Part I: Corn Distillers’ Dry Grain

Distillers0"> dry grain (DDG) was derivatized either by carboxymethylation, glutaration, maleiation, phthallation, or succination in order to produce anionic materials suitable for complexation with soy protein isolate. Infrared spectroscopy confirmed that derivatization of DDG by all reagents was successful. Blending of derivatized anionic products with soy protein resulted in instant precipitation of gels. The gels were centrifuged, molded, and dried into solid pellets with tensile strengths as high as 1.67MPa, suggesting that these materials could be promising as biodegradable structural materials. Infrared spectroscopy suggested the possibility of complexes forming between soy protein isolate and each of the derivatized DDG samples.     

中国加入WTO对环保机械企业产生的影响

中国加入WTO将使国内环保企业竞争更为激烈 ,使国内环保机械企业生存变得更为艰难。同时 ,由于经验丰富的国外企业已将凭借实力占据国际市场 ,使得我国环保机械企业在国际市场竞争中处于不利地位。从另一方面讲 ,中国加入WTO可以促进我国政府采取有力措施 ,加强对环保市场的监管 ,克服无序竞争 ,为国内企业营造良好的竞争环境 ;加入WTO可以加快国内环保机械企业技术创新 ,开发具有国际水准的拳头产品 ,增强市场竞争力 ,同时 ,可以推动国内产业结构调整及资本运营 ,使环保机械企业快速发展壮大 ;另外 ,WTO的加入可以迫使国内环保机械企业学习国外先进经验 ,掌握全球经济知识 ,夯实参与国际市场竞争的基础。     

大气中多环芳烃气固相分配与颗粒物粒径的关系

采集了2005年5月16日～6月3日上海市桃浦地区气相样品、TSP样品及不同粒径的颗粒物样品.用GC-MS对各样品中美国EPA规定优先控制的16种多环芳烃(PAHs)做了定量分析.结果表明,大气中PAHs的气固相分配系数(KP)和各物质的过冷饱和蒸气压(pl⁰)呈良好的线性相关.多元线性回归分析表明,PAHs的气固相分配受颗粒物粒径大小的影响,粒径越大,对PAHs的气固相分配影响越大;过冷饱和蒸气压越高,气固相分配越易受到粒径大小的影响.     

Strictly protected areas are not necessarily more effective than areas in which multiple human uses are permitted

The International Union for Conservation of Nature (IUCN) classifies protected areas into six categories, ranging from strict nature reserves to areas where multiple human uses are permitted. In the past, many researchers have questioned the effectiveness of multiple-use areas, fueling an unresolved debate regarding their conservation value. The literature so far has been inconclusive: although several studies have found that strictly protected areas are more effective, others have found the opposite, and yet others that the two types do not differ. To help resolve this debate, we reviewed the literature on protected areas and conducted our own analysis using > 19 000 terrestrial protected areas worldwide. We found that the differences between strictly protected areas and areas in which multiple human uses are permitted are often small and not statistically significant. Although the effectiveness of protected areas worldwide varies, other factors, besides their assigned IUCN category, are likely to be driving this pattern.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01426-5) contains supplementary material, which is available to authorized users.     

SCR气氛下Ce-W/TiO2催化剂的脱硝协同脱汞特性

在固定床反应器上研究了反应温度和烟气组分对Ce-W/TiO₂（物质的量比Ce：W=2：1）催化剂脱硝协同脱汞活性的影响.结果表明：反应温度对该催化剂的脱硝脱汞效率影响显著,在280~400℃温度区间,脱硝效率随温度升高而升高,而脱汞效率在温度为280℃与360℃的条件下较高,360℃时兼具最好的脱硝与脱汞效率.在SCR气氛中,HCl对Hg⁰的氧化脱除有极大的促进作用,低浓度的HCl也有利于脱硝效率的提高,但HCl浓度过高对NO的脱除有抑制作用;SO₂的存在对脱硝过程可起到促进作用,对Hg⁰的氧化有抑制作用.利用BET,XRD,SEM,TPD,XRF,NH3-TPD等分析手段对反应前后催化剂进行表征,结果表明：Ce-W/TiO₂无微孔结构,活性组分CeO₂和WO₃以高度分散的形式分布于载体表面.280℃条件下部分Hg以HgCl₂的形式吸附于反应后催化剂表面,随着反应温度的升高催化剂表面吸附态的汞急剧降低.SCR气氛中的HCl与SO₂会影响催化剂表面酸性,同时增加Cl和S元素含量,进而影响该催化剂的脱硝与脱汞效率.     

氯改性活性炭吸附单质铅(Pb0)的机理

利用量子化学中密度泛函方法系统研究氯改性活性炭吸附单质铅（Pb⁰）的机理,明确了氯改性对活性炭吸附Pb⁰的影响,计算得到吸附过程中各个吸附构型的吸附能、重要键长、对应的Mayor键级和铅的Mulliken原子电荷.几何优化选用B3LYP方法结合def2-SVP基组,单点能任务选用PWPB95双杂化泛函结合def2-TZVP基组进行计算.结果表明：对于扶手椅型（armchair）活性炭,氯改性将使活性炭对Pb⁰的吸附能降低74.034kJ/mol;对于锯齿型（zigzag）活性炭,氯改性基本不会改变活性炭对Pb⁰的吸附能力,因此氯改性总体上会减弱活性炭对Pb⁰的吸附作用,但是吸附类型依然为强烈的化学吸附.分别应用电子密度分布和Mayor键级进一步验证纯活性炭和氯改性活性炭对Pb⁰吸附类型,结果与吸附能分析一致.Mayor键级分析表明氯原子通过改变周围碳原子活性影响Pb⁰的吸附,而不是与Pb⁰直接作用.Mulliken原子电荷分析表明铅的原子电荷正相关于活性炭对其的吸附能,铅的原子电荷越大,对应的吸附构型的吸附能越高.此外笔者发现Pb⁰的引入对氯改性活性炭继续吸附Pb⁰有抑制作用.     

ANAMMOX菌铁自养反硝化工艺的稳定性

在非严格厌氧的连续流反应器中,通过调节进水pH、外加一定浓度的Fe~(2+)以及定期更换新鲜铁粉这3种运行方式探讨维持厌氧氨氧化(ANAMMOX)菌利用零价铁去除硝酸盐反应体系长期稳定运行的适宜条件.结果表明,随着反应进行、受零价铁表面钝化的影响,该体系硝酸盐去除率逐渐下降,反应器难以持续运行.在一定范围内降低进水pH(5～7),或者额外投加一定量的Fe~(2+)对改善该反应体系的稳定性效果不显著.通过定期更换新鲜铁粉的方式,可以有效提高硝酸盐去除率、增强反应器稳定性.相比对照组可稳定运行7 d,实验组可至少稳定运行60 d,硝酸盐平均去除率提高22. 23%.因此,采取适宜措施保证体系内有足够具有活性的零价铁、消除零价铁钝化的不利影响,是ANAMMOX菌利用零价铁去除硝酸盐反应体系高效、稳定运行的关键.