Carbonyls in the metropolitan area of Mexico City: calculation of the total photolytic rate constants Kp(s(-1)) and photolytic lifetime (tau) of ambient formaldehyde and acetaldehyde

A great number of studies on the ambient levels of formaldehyde and other carbonyls in the urban rural and maritime atmospheres have been published because of their chemical and toxicological characteristics, and adverse health effects. Due to their toxicological effects, it was considered necessary to measure these compounds at different sites in the metropolitan area of Mexico City, and to calculate the total rate of photolytic constants and the photolytic lifetime of formaldehyde and acetaldehyde. Four sites were chosen. Sampling was carried out at different seasons and atmospheric conditions. The results indicated that formaldehyde was the most abundant carbonyl, followed by acetone and acetaldehyde. Data sets obtained from the 4 sites were chosen to calculate the total rate of photolysis and the photolytic lifetime for formaldehyde and acetaldehyde. Maximum photolytic rate values were obtained at the maximum actinic fluxes, as was to be expected.     

Paying for information: partial loads in central place foragers

Information about food sources can be crucial to the success of a foraging animal. We predict that this will influence foraging decisions by group-living foragers, which may sacrifice short-term foraging efficiency to collect information more frequently. This result emerges from a model of a central-place forager that can potentially receive information on newly available superior food sources at the central place. Such foragers are expected to return early from food sources, even with just partial loads, if information about the presence of sufficiently valuable food sources is likely to become available. Returning with an incomplete load implies that the forager is at that point not achieving the maximum possible food delivery rate. However, such partial loading can be more than compensated for by an earlier exploitation of a superior food source. Our model does not assume cooperative foraging and could thus be used to investigate this effect for any social central-place forager. We illustrate the approach using numerical calculations for honeybees and leafcutter ants, which do forage cooperatively. For these examples, however, our results indicate that reducing load confers minimal benefits in terms of receiving information. Moreover, the hypothesis that foragers reduce load to give information more quickly (rather than to receive it) fits empirical data from social insects better. Thus, we can conclude that in these two cases of social-insect foraging, efficient distribution of information by successful foragers may be more important than efficient collection of information by unsuccessful ones.     

基于层次分析法的中原经济区流域水系统健康评价

为了在水资源与水环境双重制约下制订人水和谐发展的政策提供决策支持,以我国中原经济区这一重点开发区域为例,基于层次分析法构建了以水系统自然条件、水系统服务功能及人类活动影响三要素(共计20项指标)为基础的流域水系统健康评价体系,并以2011年作为评价年,将中原经济区的水资源二级区作为基本流域单元对水系统健康状况进行评价. 结果表明:中原经济区9个水资源二级区中,除了淮河上游水资源二级区(3.20分,完全健康状态为5.00分)为基本健康状态、汉江水资源二级区(2.77分)和三门峡至花园口水资源二级区(2.18分)为亚健康状态以外,其余水资源二级区(0.55~1.77分)均为不健康及极不健康状态. 分析显示,人类活动影响是影响中原经济区内各流域水系统健康状况的主要原因,人口众多、工农业开发活动强度大使得其对水资源需求巨大. 部分水资源二级区对地下水资源依赖程度较高,造成不同程度的地下水超采现象. 伴随着高强度水资源利用的是水污染物的高强度排放,部分河流水污染状况严重,甚至在局部地区造成了地下水污染. 这种不健康的状态在中原经济区内由南向北随着水系统自然条件和水系统服务功能的降低呈加重趋势.      

中国东中西部经济带的水环境库兹涅茨假说实证及其影响因素研究

“八五”至“十二五”期间,中国取得巨大的经济成果的同时带来了严重的水环境污染问题.文章分析了东中西部三大经济带经济发展及COD和氨氮两种主要水污染排放的差异,及其与经济发展的关系进行了EKC假说的实证研究.研究结果表明,部分污染物的拟合曲线尚处于上升阶段,未能出现典型的倒U型曲线,可能导致水环境质量恶化.环境基础设施建设、人口分布和产业结构等因素与COD和氨氮的排放量密切相关,因此,中国必须采取各种环境管理和技术手段,促使区域水污染物排放量指标与经济发展的拟合曲线出现转折点,改善水环境质量.     

Willingness to pay to improve domestic water supply in rural areas of Central Tanzania: Implications for policy

This analysis estimates willingness to pay to improve community-based rural water utilities in the Dodoma and Singida Regions of Central Tanzania, using Multinomial Logit functions. An estimate of willingness to pay provides an indication of the demand for improved services and potential for them being sustainable. Surveys were conducted in a total of 30 villages in the two regions. In the Dodoma Region, about 14% of respondents indicated that they were satisfied with the status quo, 64% suggested increasing water discharge and watering points, and 22% proposed other improvements relating to water quality. In the Singida Region, 31% of the respondents were satisfied with the status quo, 59% wanted deeper boreholes and watering points, and 10% indicated other types of improvement relating to water quality. The Multinomial Logit functions indicated that the interaction between the water quality variable and proposed bids were important in making choices with reference to the type of improvement desired. Respondents who wanted to increase water supply in Dodoma Region were willing to pay 32 Tsh above the existing tariff of 20 Tsh/bucket. In the Singida Region, the analogous amount was 91 Tsh per household per year above the existing user fee of 508 Tsh per household per year. If the tariff or user fees have to be increased, the estimated average potential revenue for the surveyed villages was 252 million Tsh/year (US$265 263) in the Dodoma Region, and 5.2 million Tsh/year (US$5474) in the Singida Region. In the future, strategic planning is needed to ensure that improvements proposed potentially improve cost recovery initiatives and increase the level of consumer satisfaction. Also, care will be needed to ensure that more disadvantaged community members do not suffer unduly from increases in tariff or user fees.     

Effects of stewardship on protected area effectiveness for coastal birds

Evaluation of protected area effectiveness is critical for conservation of biodiversity. Protected areas that prioritize biodiversity conservation are, optimally, located and managed in ways that support relatively large and stable or increasing wildlife populations. Yet evaluating conservation efficacy remains a challenging endeavor. We used an extensive community science data set, eBird, to evaluate the efficacy of protected areas for birds across the Gulf of Mexico and Atlantic coasts of the United States. We modeled trends (2007–2018) for 12 vulnerable waterbirds that use coastal areas during breeding or wintering. We compared two types of protected areas—sites where conservation organizations implemented active stewardship or management or both to reduce human disturbance (hereafter stewardship sites) and local, state, federal, and private protected areas managed to maintain natural land cover (hereafter protected areas)—as well as unprotected areas. We evaluated differences in trends between stewardship, protected, and unprotected areas across the Gulf and Atlantic coasts as a whole. Similar to a background sample, stewardship was known to occur at stewardship sites, but unknown at protected and unprotected areas. Four of 12 target species—Black Skimmer (Rynchops niger), Brown Pelican (Pelecanus occidentalis), Least Tern (Sternula antillarum), and Piping Plover (Charadrius melodus)—had more positive trends (two to 34 times greater) at stewardship sites than protected areas. Furthermore, five target species showed more positive trends at sites with stewardship programs than unprotected sites during at least one season, whereas seven species showed more positive trends at protected than unprotected areas. No species had more negative trends at stewardship sites than unprotected areas, and two species had more negative trends at protected than unprotected areas. Anthropogenic disturbance is a serious threat to coastal birds, and our findings demonstrate that stewardship to reduce its negative impacts helps ensure conservation of vulnerable waterbirds.     

Regulating groundwater use: The challenges of policy implementation in Guanajuato,Central Mexico

Around the world it has proven very difficult to develop policies and interventions that ensure socio-environmentally sustainable groundwater use and exploitation. In the state of Guanajuato, Central Mexico, both the national government and the decentralized state government have pursued to regulate groundwater use through direct state control, groundwater markets, energy pricing, and user self-regulation. We present and analyze these regulatory mechanisms and their outcomes in the field. We argue that the close interdependencies of these regulatory mechanisms have pre-empted the effectiveness of these policy instruments as well as that of other measures aimed at reducing groundwater use in order to advance towards sustainable exploitation levels.     

集中供热项目环境效益分析——以某市集中供热项目为例

介绍了某市新区供热现状,并对预测模型AERMOD的运行参数及数据来源进行了简要说明,根据区内供热现状及采取集中供热方式后新区冬季采暖集中供热锅炉烟气污染物排放源强的变化情况,采用AERMOD模型分别进行了预测。在此基础上,通过对比分析,得出了大型集中供热工程具有明显环境效益的结论。