Acid generation upon thermal concentration of natural water: The critical water content and the effects of ionic composition

Thermal evaporation of a variety of simulated pore waters from the region of Yucca Mountain, Nevada, produced acidic liquids and gases during the final stages of evaporation. Several simulated pore waters were prepared and then thermally distilled in order to collect and analyze fractions of the evolved vapor. In some cases, distillates collected towards the end of the distillation were highly acidic; in other cases the pH of the distillate remained comparatively unchanged during the course of the distillation. The results suggest that the pH values of the later fractions are determined by the initial composition of the water. Acid production stems from the hydrolysis of magnesium ions, especially at near dryness. Near the end of the distillation, magnesium nitrate and magnesium chloride begin to lose water of hydration, greatly accelerating their thermal decomposition to form acid. Acid formation is promoted further when precipitated calcium carbonate is removed. Specifically, calcium chloride-rich pore waters containing moderate (10–20 ppm) levels of magnesium and nitrate and low levels of bicarbonate produced mixtures of nitric and hydrochloric acid, resulting in a precipitous drop in pH to values of 1 or lower after about 95% of the original volume was distilled. Waters with either low or moderate magnesium content coupled with high levels of bicarbonate produced slightly basic fractions (pH 7–9). If calcium was present in excess of bicarbonate, waters containing moderate levels of magnesium produced acid even in the presence of bicarbonate, due to the precipitation of calcium carbonate. Other salts such as halite and anhydrite promote the segregation of acidic vapors from residual basic solids. The concomitant release of wet acid gas has implications for the integrity of the alloys under consideration for containers at the Yucca Mountain nuclear waste repository. Condensed acid gases at very low pH, especially mixtures of nitric and hydrochloric acid, are capable of corroding even alloys, such as nickel-based Alloy 22, which are considered to be corrosion-resistant under milder conditions.     

Ecosystem services in coupled social–ecological systems: Closing the cycle of service provision and societal feedback

Both the ‘cascade model’ of ecosystem service provision and the Driver-Pressure-State-Impact-Response framework individually contribute to the understanding of human–nature interactions in social–ecological systems (SES). Yet, as several points of criticism show, they are limited analytical tools when it comes to reproducing complex cause–effect relationships in such systems. However, in this paper, we point out that by merging the two models, they can mutually enhance their comprehensiveness and overcome their individual conceptual deficits. Therefore we closed a cycle of ecosystem service provision and societal feedback by rethinking and reassembling the core elements of both models. That way, we established a causal sequence apt to describe the causes of change to SES, their effects and their consequences. Finally, to illustrate its functioning we exemplified and discussed our approach based on a case study conducted in the Alpujarra de la Sierra in southern Spain.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0651-y) contains supplementary material, which is available to authorized users.     

Influences on Wood Load in Mountain Streams of the Bighorn National Forest,Wyoming, USA

We documented valley and channel characteristics and wood loads in 19 reaches of forested headwater mountain streams in the Bighorn National Forest of northern Wyoming. Ten of these reaches were in the Upper Tongue River watershed, which has a history of management including timber harvest, tie floating, and road construction. Nine reaches were in the North Rock Creek watershed, which has little history of management activities. We used these data to test hypotheses that (i) valley geometry correlates with wood load, (ii) stream gradient correlates with wood load, and (iii) wood loads are significantly lower in managed watersheds than in otherwise similar unmanaged watersheds. Statistical analyses of the data support the first and third hypotheses. Stream reaches with steeper valley side slopes tend to have higher wood loads, and reaches in managed watersheds tend to have lower wood loads than reaches in unmanaged watersheds. Results do not support the second hypothesis. Shear stress correlated more strongly with wood load than did stream gradient, but statistical models with valley-scale variables had greater explanatory power than statistical models with channel-scale variables. Wood loads in stream reaches within managed watersheds in the Bighorn National Forest tend to be two to three times lower than wood loads in unmanaged watersheds.     

基于物联网的麦积山石窟环境监测系统应用分析

简述了麦积山彩色泥塑佛像及壁画文物保护与管理监测,以及物联网技术构建文物保护微环境监测系统。针对麦积山石窟环境监测现状和存在的问题,分析了基于物联网应用的监测和传感技术在石窟实施全覆盖、实时监控的方式,以及其优势和可行性。     

湖北宣恩七姊妹山天师栗(Aesculus wilsonii)群落特征

天师栗（Aesculus wilsonii）是我国特有的珍稀树种,其天然分布比较零散,极少有大面积的自然群落存在。对湖北宣恩七姊妹山天然分布的天师栗群落采用相邻格子法进行调查,研究了群落的物种多样性、空间格局、群落结构和种群径级结构等群落特征。结果表明：（1）天师栗是群落的主要优势树种,其重要值为22.7,远大于重要值排在第二位的红枝柴（重要值为13.7）,且在群落中呈聚集分布类型;（2）群落物种比较丰富,相对于灌木层和草本层,乔木层丰富度指数和均匀度指数较低,优势度指数较高,说明乔木层物种没有灌木层和草本层多,且分布不均匀,但优势种作用显著,成层现象明显;（3）群落的年龄〖JP2〗结构显示,该群落虽然目前处于稳定阶段,但群落中5个优势种群的幼年个体补充都严重不足,潜在的影响群落以后的生存和发展。应采取保护措施,促进群落的自然演替.     

贡嘎山高山生态系统观测试验站——“中国生态系统研究网络”站之一

贡嘎山高山生态系统观测试验站代表青藏高原东缘面积达60万平方公里的高山深谷山地生态系统类型。贡嘎山东坡从河谷到山顶可明显地分出六个山地自然垂直带,每一个带内又可分出若干亚带。自然生态系统类型多样,保存完好,海拔2000米以上基本处于未开发的原始状态,具有自然生态系统原生性强的显著特点,是开展山地生态系统观测试验的理想场地。     

National parks: north of the border

This paper traces the history of attempts to introduce National Parks into Scotland. In so doing it identifies some of the alternatives that have been considered and adopted. Finally, the paper analyses the failure of the movement to introduce National Parks into Scotland.     

Implications of environmental program planning for siting a nuclear waste repository at Yucca Mountain,Nevada, USA

The US Department of Energy (DOE) plans to conduct site characterization studies at Yucca Mountain, Nevada, to determine if the location is a suitable site for a nuclear waste repository. In lieu of traditional environmental review in accordance with the National Environmental Policy Act of 1969, the DOE is relying on an environmental assessment (EA) mandated by the Nuclear Waste Policy Act of 1982 as the cornerstone of its environmental program for the Yucca Mountain Project. Because of statutory restrictions, the EA is not based on comprehensive baseline information. Neither does it address fundamentals of environmental analysis such as ecological integrity and assessment of cumulative impacts. Consequently, the present environmental program for Yucca Mountain reflects decisions made without complete information and integrated environmental review. The shortcomings of the program risk compromising the natural integrity of Yucca Mountain and invalidating future assessment of the ability of a nuclear waste repository located at the site to protect the environment. Significant improvements are needed in the repository siting program before it can serve as a model of how society can evaluate the long-term environmental consequences of advanced technologies, as has been suggested.     

Development of tourism resources and environment conservation in China: with special reference to Taishan Mountain

By analyzing the cases in Taishan Mountain, Shandong Province and other tourist sites in China, this paper pointed out the problems in tourism management, such as resources damage, environment pollution, which are the result of tourism development, and are obstacles to the development. The paper also gave suggestion and practical ways to preserve tourism resources and environment.     

广西大瑶山自然保护区旅游资源开发与生态环境保护

介绍了大瑶山自然保护区的资源特色，分析了旅游开发中存在的制约因素和保护区开发旅游可能产生的环境影响，提出了旅游资源开发的重点和建议，以及生态环境保护的对策。