Understanding unusually high levels of peroxyacetyl nitrate (PAN) in winter in Urban Jinan, China

Peroxyacetyl nitrate(PAN), as a major secondary pollutant, has gained increasing worldwide attentions, but relevant studies in China are still quite limited. During winter of 2015 to summer of 2016, the ambient levels of PAN were measured continuously by an automatic gas chromatograph equipped with an electron capture detector(GC–ECD) analyzer at an urban site in Jinan(China), with related parameters including concentrations of O3, NO, NO_2, PM_(2.5), HONO,the photolysis rate constant of NO_2 and meteorological factors observed concurrently. The mean and maximum values of PAN concentration were(1.89 ± 1.42) and 9.61 ppbv respectively in winter, and(2.54 ± 1.44) and 13.47 ppbv respectively in summer. Unusually high levels of PAN were observed during severe haze episodes in winter, and the formation mechanisms of them were emphatically discussed. Study showed that high levels of PAN in winter were mainly caused by local accumulation and strong photochemical reactions during haze episodes, while mass transport played only a minor role. Accelerated photochemical reactions(compared to winter days without haze) during haze episodes were deduced by the higher concentrations but shorter lifetimes of PAN, which was further supported by the sufficient solar radiation in the photolysis band along with the high concentrations of precursors(NO_2, VOCs) and HONO during haze episodes. In addition, significant PAN accumulation during calm weather of haze episodes was verified by meteorological data.     

Understanding the Wicked Nature of “Unmanaged Recreation” in Colorado’s Front Range

Unmanaged recreation presents a challenge to both researchers and managers of outdoor recreation in the United States because it is shrouded in uncertainty resulting from disagreement over the definition of the problem, the strategies for resolving the problem, and the outcomes of management. Incomplete knowledge about recreation visitors’ values and relationships with one another, other stakeholders, and the land further complicate the problem. Uncertainty and social complexity make the unmanaged recreation issue a wicked problem. We describe the wickedness inherent in unmanaged recreation and some of the implications of wickedness for addressing the problem for the Front Range of the Rocky Mountains in Colorado. Conclusions about the nature of the problem are based on a problem appraisal that included a literature review and interviews of key informants. Addressing wickedness calls for institutional changes that allow for and reward the use of trust building, inclusive communication, and genuinely collaborative processes.     

Colonies of Cliff Swallows on Highway Bridges: A Source of Escherichia coli in Surface Waters1

Sejkora, Patrick, Mary Jo Kirisits, and Michael Barrett, 2011. Colonies of Cliff Swallows on Highway Bridges: A Source of Escherichia coli in Surface Waters. Journal of the American Water Resources Association (JAWRA) 47(6):1275–1284. DOI: 10.1111/j.1752‐1688.2011.00566.x Abstract: Animals, such as birds, are a source of fecal indicator bacteria and pathogens in the environment. Our objective was to determine whether a colony of cliff swallows nesting underneath a bridge would yield a measurable increase in fecal indicator bacteria (specifically Escherichia coli) in the underlying creek. When the swallows were absent, dry‐weather concentrations of E. coli upstream and downstream of the bridge (in Austin, Texas) were below the Texas contact recreation criteria. When the swallows were present, dry‐weather geometric‐mean E. coli concentrations increased significantly from upstream (43 most probable number [MPN]/100 ml) to downstream (106 MPN/100 ml) of the bridge. One exceedance and one near‐exceedance of the Texas single‐sample contact recreation criterion were observed during the swallows’ nesting phase. When the swallows were present, the downstream E. coli geometric‐mean concentration in storm events (875 MPN/100 ml) was significantly higher than the upstream concentration (356 MPN/100 ml), suggesting that runoff flushes swallow feces from the ground into the creek. Although the loading of E. coli from cliff swallows nesting under bridges can be significant (e.g., dry‐weather loading of 3.1 × 10⁸ MPN/day/nest), the zoonotic potential of the cliff swallow must be examined to determine the risk to human health from contact recreation in waters contaminated with cliff swallow feces.     

沈阳市冬季一次严重污染天气过程成因分析

为探讨沈阳市冬季重污染天气的初步成因。以2013年1月11日~16日沈阳市发生的一次严重污染天气为例,利用中国气象局的MICAPS系统和美国的HYSPLT模式,从污染形成的天气背景、污染物扩散受地形的影响情况以及外来污染物输送的气流轨迹等几方面综合分析,从而探讨此次严重污染过程的成因:长白山小高压和西部倒槽双重系统的控制下,地面吹东北风,风速较小,湿度大,不利于污染物的水平扩散;有较强接地逆温存在时,不利于污染物的垂直扩散,导致近地面污染物累积;受来自于北部和东北部低层气流的影响,将内蒙古、辽宁东北部的污染物携带到沈阳地区汇聚。     

Air quality at a snowmobile staging area and snow chemistry on and off trail in a Rocky Mountain subalpine forest, Snowy Range, Wyoming

A study was begun in the winter of 2000–2001 and continued through the winter of 2001–2002 to examine air quality at the Green Rock snowmobile staging area at 2,985 m elevation in the Snowy Range of Wyoming. The study was designed to evaluate the effects of winter recreation snowmobile activity on air quality at this high elevation site by measuring levels of nitrogen oxides (NO _x , NO), carbon monoxide (CO), ozone (O₃) and particulate matter (PM₁₀ mass). Snowmobile numbers were higher weekends than weekdays, but numbers were difficult to quantify with an infrared sensor. Nitrogen oxides and carbon monoxide were significantly higher weekends than weekdays. Ozone and particulate matter were not significantly different during the weekend compared to weekdays. Air quality data during the summer was also compared to the winter data. Carbon monoxide levels at the site were significantly higher during the winter than during the summer. Nitrogen oxides and particulates were significantly higher during the summer compared to winter. Nevertheless, air pollutants were well dispersed and diluted by strong winds common at the site, and it appears that snowmobile emissions did not have a significant impact on air quality at this high elevation ecosystem. Pollutant concentrations were generally low both winter and summer. In a separate study, water chemistry and snow density were measured from snow samples collected on and adjacent to a snowmobile trail. Snow on the trail was significantly denser and significantly more acidic with significantly higher concentrations of sodium, ammonium, calcium, magnesium, fluoride, and sulfate than in snow off the trail. Snowmobile activity had no effect on nitrate levels in snow.     

中国典型冰雪旅游地开发模式及优化路径

北京冬奥会的筹办为中国冰雪旅游发展带来巨大契机,促进了冰雪旅游地的蓬勃发展。基于冰雪旅游地系统理论,构建了冰雪旅游地发展水平评价指标体系,并利用层次分析法、熵权法及加权Topsis法,对崇礼、亚布力、神农架、西岭雪山四个中国典型冰雪旅游地发展水平进行了测度。结果表明：崇礼冰雪旅游发展水平最高,亚布力次之,神农架及西岭雪山仍有待提升。基于此,提炼出四种典型冰雪旅游地开发模式,包括资源主导内驱模式、市场主导外驱模式、资源市场双核共驱模式以及资源市场政策综合齐驱模式。同时,从冰雪旅游地系统视角,提出了中国冰雪旅游地开发优化路径。研究有助于丰富冰雪旅游开发相关理论,为中国冰雪旅游地高质量发展提供智力支撑和案例借鉴。     

上海西郊麦期氮素淋溶定位研究

上海西郊水旱轮作地中麦期的淋失研究表明，氮肥淋失的基本形态为硝酸盐氮，施肥后10d左右，形成硝酸盐氮淋溶的高峰期，在整个生育期间，随深度增加，硝酸盐氮浓度峰值向深层推移，但其渗漏深度为80cm左右。氮素的淋失主要发生在11月到次年3月的作物幼苗期，当追肥超过150kg/hm^2后，渗漏量增加很快。     

The costs of congestion and wilderness recreation

Existing research on the effects of congestion in wilderness areas suffers from problems associated with asking people directly what they would be willing to pay to avoid congestion under hypothetical circumstances. The work reported here is based on methodologies that infer conclusions from observed behavior. Two inferential methodologies are used to examine visitors' willingness to pay at three California wilderness areas during peak and off-peak use periods. Inferential methodologies do not provide unambiguous measures of consumer surplus. However, they do yield the conclusion that, with the exception of a relatively few individuals, solitude is not of overriding importance. Convenience of timing and the attributes of different wilderness areas appear to be more important than congestion.     

Relationship between recreation demand and some natural landscape elements in Turkey: A case study

The study consists of two parts. One part deals with recreation and vacation demands; the other investigates the relationship between recreation demand and some natural landscape elements preferred in the eastern Black Sea coastal zone of Turkey, which has traditionally a rich recreational culture. Home interview surveys were conducted during the summer of 1992. The recreation demand of the study area has been found to be 89.3% including potential demand. The landscape element "sea and seaside" preferred for recreation has been rated the highest in all groups of each of the five variables, namely, age, education, income, occupation, and marital status. The research reported here represents an empirical contribution to the field of landscape preference studies for recreation, especially in the developing countries.     

Access rights for outdoor recreation in New Zealand: some lessons for open country in England and Wales

Access opportunities for outdoor recreation in New Zealand and England and Wales are classified according to their conformity with collective, citizenship or exclusion rights and their degrees of permanence. Alternative criteria for the apportionment of access rights are considered in the context of this classification. Different criteria for rights apportionment are found to be appropriate according to different circumstances in the context of pluralist provision. Policy developments in New Zealand are compared with those in England. After 150 years of a dominance of collective rights in New Zealand current policy is shifting provision towards exclusionary rights. In England, there is a policy shift in the other direction, towards collective rights. Lessons for the development of collective rights in England are drawn from the New Zealand experience in relation to styles of governance, public preferences, public cost, insurance liability and the potential of markets.