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71.
72.
Long-term effects of clear-cutting and selective cutting on soil methane fluxes in a temperate spruce forest in southern Germany 总被引:1,自引:0,他引:1
Wu X Brüggemann N Gasche R Papen H Willibald G Butterbach-Bahl K 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2467-2475
Based on multi-year measurements of CH4 exchange in sub-daily resolution we show that clear-cutting of a forest in Southern Germany increased soil temperature and moisture and decreased CH4 uptake. CH4 uptake in the first year after clear-cutting (−4.5 ± 0.2 μg C m−2 h−1) was three times lower than during the pre-harvest period (−14.2 ± 1.3 μg C m−2 h−1). In contrast, selective cutting did not significantly reduce CH4 uptake. Annual mean uptake rates were −1.18 kg C ha−1 yr−1 (spruce control), −1.16 kg C ha−1 yr−1 (selective cut site) and −0.44 kg C ha−1 yr−1 (clear-cut site), respectively. Substantial seasonal and inter-annual variations in CH4 fluxes were observed as a result of significant variability of weather conditions, demonstrating the need for long-term measurements. Our findings imply that a stepwise selective cutting instead of clear-cutting may contribute to mitigating global warming by maintaining a high CH4 uptake capacity of the soil. 相似文献
73.
膜生物反应器废水处理新工艺 总被引:13,自引:0,他引:13
概述了国内外膜生物反应器的研究与应用状况;介绍了其构形与特点;分析了膜污染的成因,影响因素及防制措施;指出了今后的研究方向。 相似文献
74.
超滤技术在废水处理中的应用 总被引:7,自引:1,他引:7
文章对超滤原理、超滤膜种类、国内外超滤技术发展现状等做了较详尽的阐述,同时着重介绍了超滤技术在油田含油废水、石化含油废水、金属加工用乳化废液、纤维加工油剂废水及羊毛精制废水中回收羊毛脂的应用实例。 相似文献
75.
通过色谱柱、固定相以及载气流速的选择性实验 ,提高了气相色谱仪在观测地下水中H2 、He分离效能和检测效能。本文对此作介绍 ,以期对使用气相色谱仪进行地下水H2 、He观测的台站能有所启发和借鉴 相似文献
76.
Ryo?ShojiEmail author Takanori?Miyazaki Takashi?Niinou Mikio?Kato Hiroshi?Ishii 《Journal of Material Cycles and Waste Management》2004,6(2):142-146
We have successfully prepared a bead-type adsorbent from two materials with different adsorption characteristics. Heavy metals were removed by greatly swollen egg shell membrane-conjugated chitosan beads. The egg shell membrane accumulated and removed precious metal ions from a dilute aqueous solution with a high affinity in a short contact time. Experiments suggested that chitosan beads could take up gold ions with great capacity and selectivity by conjugation with egg shell membrane. Under certain conditions, the selective removal of gold and copper in a mixture of gold and copper ions by egg shell membrane-conjugated chitosan beads was 100% and 2%, respectively. Egg shell membrane-conjugated chitosan beads can be seen as a promising material to recover gold in wastewater from various industries, such as electroplating. 相似文献
77.
Power line rights-of-way provide a major portion of the shrub habitat in New York. Since this habitat type is on the decline,
many of the birds dependent on shrub habitat are also declining. The methods used to control right-of-way vegetation could
therefore have serious impacts on several birds of conservation concern. Since New York is increasingly using selective herbicide
treatments in vegetation management, we sought to investigate the potential impacts of these treatments on nesting birds.
The study looked at plots in two adjacent rights-of-way before and after a selective herbicide treatment in one of the rights-of-way.
We investigated three bird species: alder flycatcher (Empidonax alnorum), chestnut-sided warbler (Dendroica pensylvanica), and gray catbird (Dumetella carolinensis). All three species exhibited a preference for shrub vegetation around nest sites. The selective herbicide treatment did
not significantly decrease that shrub vegetation, and neither the density nor the nesting success of the three species declined
following the treatment. We conclude that selective herbicide vegetation management encourages the development of shrub habitat
without negatively impacting the birds nesting in the habitat. 相似文献
78.
Amir P. Nejadhashemi Joseph M. Sheridan Adel Shirmohammadi Hubert J. Montas 《Journal of the American Water Resources Association》2007,43(3):744-756
Abstract: Evaluating the relative amounts of water moving through the different components of the hydrological cycle is required for precise management and planning of water resources. An important aspect of this evaluation is the partitioning of streamflow into surface (quick flow) and base‐flow components. A prior study evaluated 40 different approaches for hydrograph‐partitioning on a field scale watershed in the Coastal Plain of the Southeastern United States and concluded that the Boughton’s method produced the most consistent and accurate results. However, its accuracy depends upon the proper estimation of: (1) the end of surface runoff, and (2) the fraction factor (α) that is function of many physical and hydrologic characteristics of a watershed. Proper identification of the end of surface runoff was accomplished by using a second derivative approach. Applying this approach to 12 years of separately measured surface and subsurface flow data from a field scale watershed (study area) proved to be accurate for 87% of the time. Estimation of the α value was accomplished in this study using two steps: (1) alpha was fitted to individual hydrographs: and, (2) a regression equation that determines these alpha values based on climatological factors (e.g., rainfall, evapotranspiration) was developed. Using these strategies improved the streamflow partitioning method’s performance significantly. 相似文献
79.
电子废弃物的资源化既能实现资源的二次利用,又能防止环境污染,具有重要的理论意义和应用价值.运用灰色理论对离心复合力场回收废弃电路板金属过程中反冲水、转速和浓度等操作参数对分选效果(精矿品位和精矿的回收率)的影响进行了研究,建立了基于GM(0,N)灰色模型的离心复合力场回收废弃电路板分选模型.经验证模型精度较高. 相似文献
80.
低水平放射性废水中钚的分析方法研究进展 总被引:1,自引:0,他引:1
钚是重要的核燃料,也是一种极毒的放射性核素,在核燃料循环和放射性废物处置过程中占有重要地位.近些年来,钚在自然水体中的含量、分布引起人们的关注.科研工作者针对低水平放射性废水,核设施周围自然水体,核试验、核事故情况下可能污染的自然水体等,建立了一些钚的分析方法.作者在对这些方法进行了比较的基础上,提出了一种在盐酸体系中用TEVA树脂负压微色谱柱液闪法将水溶液中钚与其他锕系元素及金属离子分离并测量的新方法.该方法有望在日常和应急监测中的得到应用. 相似文献