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481.
A multi-media bio-PRB reactor was designed to treat groundwater contaminated with petroleum hydrocarbons. After a 208-day bioremediation, combined with the total petroleum hydrocarbons content in the groundwater flowed through the reactor, microbiological characteristics of the PRB reactor including microbes immobilized and its dehydrogenase activity were investigated. TPH was significantly reduced by as much as 65% in the back of the second media layer, whereas in the third layer, the TPH content reached lower than 1 mg l?1. For microbes immobilized on the media, the variations with depth in different media were significantly the same and the regularity was obvious in the forepart of the media, which increased with depth at first and then reduced gradually, while in the back-end, the microbes almost did not have any variations with depth but decreased with the distance. The dehydrogenase activity varied from 2.98 to 16.16 mg TF L?1 h?1 and its distribution illustrated a similar trend with numbers of microbial cell, therefore, the noticeable correlation was found between them. 相似文献
482.
利用2003-2012年3~10月秦皇岛地区5个气象站雷暴监测和雷电灾害资料,采用数理统计、天气综合分析方法,得出秦皇岛地区雷暴天气的时空尺度分布特征为:全区年雷暴发生频次总体上呈递减趋势,其中,2005年35次,2008年33次,2012年20次;6月份为全年雷暴发生的峰值时段,7月、8月次之,且与秦皇岛本地主汛期相吻合;在海岸带地区由于受海洋条件影响,个别年份雷暴最早出现在2月份,最晚出现在11月中旬;雷暴天气的日时段主要出现在下午至傍晚,占70%,夜间占20%,其他时段为10%;北部山区的雷电频次大于沿海地区,对应电力、化工等行业雷电灾害呈下降趋势,但是通讯、计算机、家电等弱电系统雷击事件呈递增趋势。 相似文献
483.
本文对我国目前在防减灾工程性措施方面存在的问题进行了分析探讨,阐述了在目前国情下强化减灾的非工程性措施的必要性和重要性,并对减灾的非工程性措施的具体作法进行了论述。 相似文献
484.
Whangapoua Estuary, Great Barrier Island, New Zealand, is central to a proposed Marine Reserve, and is currently managed for
conservation by the Department of Conservation. This paper describes the sequential impacts of Maori and European people on
the process of estuarine vegetation succession in time and space, and the rate of estuarine sedimentation. Multiple cores
from one estuary gave confidence in assessing the temporal sequence of vegetation change, but bioturbation and other disturbance
factors made it difficult to interpret 14C dates from the estuarine environment. The modern vegetation zonation pattern on the estuary is an active succession, which
has been generated by rapid estuary in-filling, probably initiated as a consequence of erosion following Maori burning of
the adjacent forest. European forest clearance for agriculture resulted in a further increase in estuarine sedimentation,
and may have re-activated earlier sediments trapped in adjacent swamps. The combined effects of two phases of human exploitation
have resulted in large-scale loss of nutrients and top-soil from catchments throughout Great Barrier Island. Conservation
management of the estuary should take account of the anthropogenic impacts that have driven the plant succession and created
the current vegetation zonation pattern. This pattern is neither static nor ‘natural’, but rather an on-going response to
the changing human activities in the surrounding catchment. 相似文献
485.
486.
通过对比分析,阐述了FP型盘管空调器在盘管排数、管径、肋片型式等结构设计对热工性能的影响,以及合理设计水流速度。 相似文献
487.
Fenton法处理中药废水的研究 总被引:5,自引:0,他引:5
采用Fenton氧化技术对中药废水进行实验处理,对主要操作条件及其对实验处理效果的影响进行了实验研究。主要考察了废水pH、H2O2投加量、Fe^2+投加量及温度等对废水中CODcr去除率的影响。实验结果显示,在pH=3.0,H2O2投加量为4/5Qth,Fe^2+浓度为7.9×10^-3mol.L-1,20℃的情况下反应80 m in后CODcr去除率可以达到71.40%,Fenton氧化反应对中药废水有比较好的处理效果,改善了废水的可生化性,有利于进一步进行生化处理。 相似文献
488.
Batch experiments were carried out to investigate the effects of initial atrazine concentrations and consecutive desorption steps on the desorption characteristics of atrazine from a sandy loam soil.As initial atrazine concentration increased,the average percentage of atrazine desorption on the sandy loam soil ranged gradually from 23.1% to 38.5% after five consecutive desorption steps.The values of the Freundlich capacity parameter,kdes,derived from the initial concentration and time-dependent desorption isotherm were consistently higher than those associated with sorption.The opposite trend was observed only for the values of nonlinear parameter,ndes,from the initial concentration-dependent desorption isotherms.Atrazine hydrolysis to hydroxyatrazine and bound residue formation were mainly responsible for the observed hysteresis in its sorption and desorption isotherms.For the initial concentration-dependent desorption isotherms,as initial atrazine concentration increased,the values of hysteretic coefficients ω and λ decreased,and H values increased.However,the relationships between initial atrazine concentration and hysteretic coefficients were not pronounced for ω,H,or λ.For the time-dependent desorption isotherms,λ and H values increased as the atrazine desorption step proceeded.The correlation between hysteretic coefficient and desorption step was highly significant for λ (P 0.0001),but not for H. 相似文献
489.
490.