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671.
《Environmental Forensics》2013,14(3):175-189
During the last decade, the fuel oxygenate methyl tertiary butyl ether (MTBE) has received widespread attention as a potential threat to water quality, primarily due to leaking underground gasoline storage tanks and watercraft with two-stroke engines. In this article, we examine the annual detection frequency, number of new source detections, and concentration of MTBE detected in California's public drinking water groundwater and surface water sources from 1995 to 2002. This work builds on our previous evaluations of California's water quality monitoring database. However, it is unique in that it includes separate evaluations for groundwater and surface water sources that are of greatest concern to regulators, and which are likely being used for current public consumption. Our evaluations also include full-year data for 2002 (which have not been published previously) and an analysis of how the sampling and reported detections of MTBE vary by geographic location. We find that MTBE was generally detected (at any level) in approximately 0.5-0.9% and 0.2-0.4% of all groundwater sources assuming a one-detection and two-detection criterion, respectively. The overall detection frequency for MTBE in surface water sources is significantly higher than for groundwater sources, although these surface water detections appear to have substantially declined since 1996 (e.g., 7-9% for all surface water sources during 1996 to 1999 and 4% for all surface water sources during 2000 to 2002, assuming a one-detection criterion). The detection frequency of MTBE concentrations at or above the state drinking water standards in all drinking water sources (both groundwater and surface water sources) and the subset of drinking water sources that are likely to currently be delivered to consumers is markedly lower (and often zero). Despite the significant increase in water sampling over time, the number of new drinking water sources found to contain MTBE in California has not increased at the same rate and appears to have remained relatively stable or to have decreased since 1998. The data also show that nearly all of the 58 counties in California have routinely sampled at least some of their groundwater and surface water sources for MTBE over the last 8 years. Geographical evaluations show that MTBE has been detected (at least once) in groundwater sources in 34 counties and in surface water sources in 18 counties but has only been detected routinely (i.e., for 3 or more years) in 16 and 7 counties, respectively. Detected concentrations of MTBE are also generally below state drinking water standards, particularly for surface water sources. In short: (1) MTBE is rarely found in California groundwater or surface water sources that are of greatest concern to regulators or the public, and (2) drinking water detections of MTBE are expected to decline in the future due to the pending phase-out of MTBE and recent regulatory programs aimed at controlling gasoline releases from underground storage tanks and two-stroke-engine watercraft. 相似文献
672.
针对山西阳城电厂2×600 MW机组脱硫系统烟气换热器(简称GGH)在运行中频繁堵塞、差压大、增压风机运行电流偏大、影响机组带负荷及脱硫系统安全稳定性下降等问题进行了分析,提出了GGH改造方案及运行优化措施,确保了机组及脱硫系统的安全、稳定运行. 相似文献
673.
Yinghui Mo Liping Sun Lu Zhang Jianxin Li Jixiang Li Xiuru Chu Liang Wang 《Frontiers of Environmental Science & Engineering》2023,17(4):49
674.
675.
Human activities have impacted the environment since the first toolmakers learned to make fire. As the human population has grown and changed, so has our impact on the environment. Currently the world's population is estimated at 6–7 billion, and that number of people, along with the billions of domesticated animals, and their activities, are large enough to have major global and regional impacts. Climate change, declining fish populations in the oceans, and ever decreasing ranges for “wild” ecosystems are the most obvious impacts. Other impacts may be surprising to many people, especially those impacts that are regional and not raised to the level of international concern.This paper will take a very high level look at a number of global, regional and local human interactions with the environment, and how mitigating those impacts requires a very broad and multi-disciplinary response. Examples will focus on water, carbon and energy, all of which are needed for life, as we know it, to exist. Stewardship will be shown to involve determination and monitoring of many key indicators and environmental processes, followed by the tough decisions on how to steward those processes to maintain a healthy environment for all the planet's inhabitants. Stewardship is not easy, and there are few cases where solutions can be neatly divided into good or bad, positive or negative. 相似文献
676.
This paper summarises the methodology and results of work involved in the investigation of energy demand in six Chinese villages included in the SUCCESS Project. The procedures used to collect data associated with local energy demand are explained and the approach to data analysis is explained. Results are provided in terms for delivered energy consumption, as an indicator of energy demand; primary energy consumption, as an indicator of energy resource depletion; and carbon dioxide emissions, as an indicator of global climate change. Similarities and differences between results for this sample of villages are considered. The important causes of differences in results are investigated. 相似文献
677.
A. Koenig 《Behavioral ecology and sociobiology》2000,48(2):93-109
Van Schaik’s socioecological model predicts interrelations among food distribution, competitive regimes, and female social
relationships. To test the internal consistency of the model, feeding competition was examined in three differently sized
groups of a forest-dwelling population of Hanuman langurs (Semnopithecus entellus). The nutritional condition of females was used as a direct indicator of feeding competition and related to the seasonal
variation in resource distribution and abundance. Female dominance hierarchies were characterized by displacements. Dominance
hierarchies were significantly linear and relatively stable, but less so with increasing group size. Physical condition correlated
with dominance rank and high-ranking females were in the best condition, indicating within-group contest competition. The
strength of this relationship became less pronounced with increasing group size. The females of the medium-sized group were
in the best physical condition indicating between-group contest plus within-group scramble competition. Closer examination
revealed variable costs and benefits of group foraging with a predominance of within-group scramble competition when food
was more abundant. The results support some basic predictions of the model. Limiting food abundance was bound to ubiquitous
within-group scramble competition. The use of clumped resources translated into differences in net energy gain based on dominance.
In contrast to the predictions, group-size-related costs and benefits were related to food abundance instead of food distribution.
As predicted, within-group contest competition was linked to a linear dominance hierarchy. The absence of nepotism and coalitions
in Hanuman langurs may be attributed to dominance hierarchies that are unstable through time, probably minimizing fitness
gain via kin support.
Received: 25 May 1999 / Received in revised form: 18 February 2000 / Accepted: 25 February 2000 相似文献
678.
基于Landsat 7的武汉市热岛效应研究 总被引:1,自引:0,他引:1
城市化使得城市数量和规模不断增加,城市作为人类对自然环境改造最为剧烈的部分,具有独特的区域环境,其中城市内部温度显著高于周边郊区的热岛效应是一个突出的城市环境问题,受到了普遍关注和研究。武汉市是长江中游特大城市,城市热岛效应明显,但对其研究很少。利用Landsat TM6波段数据,生成武汉市城市亮温场,分析了武汉市热场的分布、大小,利用亮温场均值、方差和相对温度评价城市热岛强度,并对城市热场的范围及强度变化与城市发展规模及方向进行了分析,取得了较好的效果。 相似文献
679.
通过研究地下轨道交通现行国家标准与地方标准监测方法与评价量,探讨标准中存在的不足之处。并通过对受地下轨道交通运行过程影响的建筑物进行室内噪声与振动实地测试和数据分析,大胆提出了监测地下轨道交通排放的新思路。即采用1/3倍频程时间历程方法对列车通过全过程产生的结构传声排放与振动排放全时记录,借鉴声暴露级的方法,通过实测各频率数值变化截取列车通过时噪声事件的振动分频振级与结构传声1/3倍频程声压级。对此种方法的数据结果进行各频率噪声与振动相关性分析,得出地下轨道交通运行所产生结构传声污染排放的低频排放特性。通过研究和测量发现,轨道交通所引起的室内结构传声与振动污染能量主要集中于500 Hz 以下低频部分,其峰值出现于40~60 Hz 附近。将其与现行国家或地方标准进行比较,提出了采用特征频率作为事件判别的依据,并将各事件的最终测量结果以低频分频数据进行评价的方式,最终归纳总结了实际地下轨道交通排放频率特性并展望其测量方法。 相似文献
680.
我国作为世界第二大经济体,也是全球第一大发展中国家,对于石油的需求也是很大的。石油作为不可再生资源,虽然我国的炼油技术发展也有了非常显著的提升,但是炼油过程产生和消耗所伴随的环境问题也越来越大。为了解决炼油过程中所带来的环境问题,我们必须采取有效的措施来提升环保性能,依托节能和环保,以保证炼油工业的长期、高质量发展。 相似文献