Valuing environmental amenities through inverse optimization: Theory and case study

Amenity values of private forests are implicit but play a critical role in decision and policy making. This study presents an innovative valuation approach integrating techniques of operations research and economic theory of pricing environmental goods. A forest planning problem was inversed through altering its reward function of timber values so that the observed harvesting behavior became optimal. The discrepancy between the original and new rewards uncovered amenities values which were linked to forest attributes via hedonic models. This method was applied to a case study of the U.S. southern pine region. Depending on forest conditions, total economic values of amenities varied from zero to just under one thousand dollar per ha. At a discount rate of 3%, a typically managed forest generated on average $243 ha⁻¹ of amenities values per annum, more than twice of harvested timber values. Structural diversity and density of large pine trees were the key determinants to preserving forests for environmental amenities.     

催化裂化装置反应再生系统的危险性评价

应用故障树分析方法,对催化裂化反应器和催化裂化再生器发生火灾（爆炸）事故的原因进行分析,分别画出催化裂化反应器和催化裂化再生器发生火灾（爆炸）事故的故障树,得出最小径集合,并计算其结构重要度,根据得出的最小径集合及其结构重要度进行排序。提出预防措施,为企业的安全管理提供了可靠的理论依据。     

凝结水精处理现状及新技术应用

概述了国内凝结水精处理技术,指出树脂分离与混合的固有矛盾是其技术上的不足之处．另一不足之处是树脂分离再生工艺较为复杂,而以时间为步序的程序控制方式过于机械、简单,二者不能匹配是程控系统投运不好的主要原因。采用阳浮动床、阴浮动床、后置阳床的处理方式能彻底解决上述问题。     

Root uptake of lead by Norway spruce grown on Pb spiked soils

The root uptake of lead (Pb) by trees and the transfer of Pb by leaf litter deposition to the forest floor were investigated through a pot experiment with Norway spruce. Natural Pb and radio isotopic lead (²¹⁰Pb) were determined in needles and twigs and in the pot soil spiked with ²¹⁰Pb. Calculations of the specific activity in plant material and in the supporting pot soil showed that less than 2% of the Pb content of needles and twigs originates from root uptake and approximately 98% are deposited from the atmosphere. Atmospheric Pb has declined by a factor of 7 from 1980 to 2007 but is still a major pathway of Pb to vegetation and topsoils. The conclusion from the experiment is that the internal circulation of Pb through root uptake, translocation and litterfall, gives an insignificant input of Pb to the forest floor compared to atmospheric deposition.     

Are Bavarian Forests (southern Germany) at risk from ground-level ozone? Assessment using exposure and flux based ozone indices

Exposure and flux-based indices of O₃ risk were compared, at 19 forest locations across Bavaria in southern Germany from 2002 to 2005; leaf symptoms on mature beech trees found at these locations were also examined for O₃ injury. O₃ flux modelling was performed using continuously recorded O₃ concentrations in combination with meteorological and soil moisture data collected from Level II forest sites. O₃ measurements at nearby rural open-field sites proved appropriate as surrogates in cases where O₃ data were lacking at forest sites (with altitude-dependent average differences of about 10% between O₃ concentrations). Operational thresholds of biomass loss for both O₃ indices were exceeded at the majority of the forest locations, suggesting similar risk under long-term average climate conditions. However, exposure-based indices estimated higher O₃ risk during dry years as compared to the flux-based approach. In comparison, minor O₃-like leaf injury symptoms were detected only at a few of the forest sites investigated. Relationships between flux-based risk thresholds and tree response need to be established for mature forest stands for validation of predicted growth reductions under the prevailing O₃ regimes.     

The formation and fate of chlorinated organic substances in temperate and boreal forest soils

Background, aim and scope  Chlorine is an abundant element, commonly occurring in nature either as chloride ions or as chlorinated organic compounds (OCls). Chlorinated organic substances were long considered purely anthropogenic products; however, they are, in addition, a commonly occurring and important part of natural ecosystems. Formation of OCls may affect the degradation of soil organic matter (SOM) and thus the carbon cycle with implications for the ability of forest soils to sequester carbon, whilst the occurrence of potentially toxic OCls in groundwater aquifers is of concern with regard to water quality. It is thus important to understand the biogeochemical cycle of chlorine, both inorganic and organic, to get information about the relevant processes in the forest ecosystem and the effects on these from human activities, including forestry practices. A survey is given of processes in the soil of temperate and boreal forests, predominantly in Europe, including the participation of chlorine, and gaps in knowledge and the need for further work are discussed. Results  Chlorine is present as chloride ion and/or OCls in all compartments of temperate and boreal forest ecosystems. It contributes to the degradation of SOM, thus also affecting carbon sequestration in the forest soil. The most important source of chloride to coastal forest ecosystems is sea salt deposition, and volcanoes and coal burning can also be important sources. Locally, de-icing salt can be an important chloride input near major roads. In addition, anthropogenic sources of OCls are manifold. However, results also indicate the formation of chlorinated organics by microorganisms as an important source, together with natural abiotic formation. In fact, the soil pool of OCls seems to be a result of the balance between chlorination and degradation processes. Ecologically, organochlorines may function as antibiotics, signal substances and energy equivalents, in descending order of significance. Forest management practices can affect the chlorine cycle, although little is at present known about how. Discussion  The present data on the apparently considerable size of the pool of OCls indicate its importance for the functioning of the forest soil system and its stability, but factors controlling their formation, degradation and transport are not clearly understood. It would be useful to estimate the significance and rates of key processes to be able to judge the importance of OCls in SOM and litter degradation. Effects of forest management processes affecting SOM and chloride deposition are likely to affect OCls as well. Further standardisation and harmonisation of sampling and analytical procedures is necessary. Conclusions and perspectives  More work is necessary in order to understand and, if necessary, develop strategies for mitigating the environmental impact of OCls in temperate and boreal forest soils. This includes both intensified research, especially to understand the key processes of formation and degradation of chlorinated compounds, and monitoring of the substances in question in forest ecosystems. It is also important to understand the effect of various forest management techniques on OCls, as management can be used to produce desired effects.     

Quantifying disturbance effects on vegetation carbon pools in mountain forests based on historical data

Although the terrestrial carbon budget is of key importance for atmospheric CO₂ concentrations, little is known on the effects of management and natural disturbances on historical carbon stocks at the regional scale. We reconstruct the dynamics of vegetation carbon stocks and flows in forests across the past 100 years for a valley in the eastern Swiss Prealps using quantitative and qualitative information from forest management plans. The excellent quality of the historical information makes it possible to link dynamics in growing stocks with high-resolution time series for natural and anthropogenic disturbances. The results of the historical reconstruction are compared with modelled potential natural vegetation. Forest carbon stock at the beginning of the twentieth century was substantially reduced compared to natural conditions as a result of large scale clearcutting lasting until the late nineteenth century. Recovery of the forests from this unsustainable exploitation and systematic forest management were the main drivers of a strong carbon accumulation during almost the entire twentieth century. In the 1990s two major storm events and subsequent bark beetle infestations significantly reduced stocks back to the levels of the mid-twentieth century. The future potential for further carbon accumulation was found to be strongly limited, as the potential for further forest expansion in this valley is low and forest properties seem to approach equilibrium with the natural disturbance regime. We conclude that consistent long-term observations of carbon stocks and their changes provide rich information on the historical range of variability of forest ecosystems. Such historical information improves our ability to assess future changes in carbon stocks. Further, the information is vital for better parameterization and initialization of dynamic regional scale vegetation models and it provides important background for appropriate management decisions.     

陶瓷膜生物反应器处理生活污水膜污染后再生方法的研究

从可逆及不可逆污染的角度,研究了陶瓷膜生物反应器处理生活污水后膜的清洗再生方法,考察了水冲洗时间、化学清洗条件以及单步和多步骤化学清洗对清洗效果的影响。结果表明,先在低压、高流速、20±3℃下水冲20 min;然后在50士3℃下,用NaOH（1%）和NaClO（0.5%）混合溶液清洗50 min;再在30±3℃下,用HNO₃溶液（0.5%）清洗5 min;最后水冲装置至中性,膜的清水通量可恢复到80%以上。     

包埋碳纳米管海藻酸钠凝胶球吸附苯酚的研究

研究了水溶液中碳纳米管及包埋固定于海藻酸钠凝胶球中的碳纳米管吸附苯酚的特性,测定了温度、pH值、转速等因素对吸附的影响,并对吸附剂进行了热脱附再生.绘制了吸附等温线,对吸附机理进行探讨.结果表明,碳纳米管及包埋于海藻酸钠凝胶球中的碳纳米管对苯酚的吸附平衡受pH和转速影响不显著,受温度影响显著,简单的热再生即有很好的再生效果.通过方程拟合,2种吸附剂对苯酚的吸附均符合Langmuir和Freundlich型吸附等温式.     

In-stand scenic beauty of variable retention harvests and mature forests in the U.S. Pacific Northwest: The effects of basal area, density, retention pattern and down wood

Tensions between amenity- and timber-based economies in the U.S. and Canadian Pacific Northwest motivated a study of scenic beauty inside mature forests and timber harvests. A diverse sample of regional forests, measures of forest structure, and large, representative samples of photographs and public judges were employed to measure scenic beauty inside un-harvested mature and old-growth forests, and timber harvests. The latter varied systematically in down wood levels and retention level and pattern. Scenic beauty tended to be optimized at a basal area of 110–155 m³/ha and/or 700–900 trees/ha. Older forests and those with larger trees were perceived to be more beautiful. In harvests, greater retention levels, less down wood, and dispersed rather than aggregated retention patterns contributed to aesthetic improvements. Green-tree retention harvests offer considerable potential gains in perceived scenic beauty compared to perceived very ugly clearcuts, particularly at higher retention levels. These gains are more reliable from dispersed retention patterns. The silvicultural parameters studied change strength in affecting scenic beauty with changes in retention level. These interactions are explored in relation to a range of scenic quality objectives as an aid to planners, visual impact analysts, and silviculturists.