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991.
The Kuihe River is in Xuzhou, Jiangsu, China. It contains high concentrations of nitrogen. The water in the Kuihe River recharges
the groundwater via riverbank filtration (RBF) along the Xucun and Huangqiao reaches, which are characterized by unsaturated
and saturated percolations, respectively. The two sections were selected to study the effectiveness of RBF to the nitrogen
removal from the infiltrating river water. The results showed that the RBF in the saturated percolation had the potential
to remove the nitrogen through biochemical processes. The nitrogen-removal rates were more than 95% over the monitoring period.
However, the RBF in the unsaturated percolation resulted mainly from the physical process and thus had no efficacy for nitrogen
removal. 相似文献
992.
A series of polyaluminum chloride sulfate (PACS) coagulants, which have different SO42–/Al3+ and OH/Al (γ) mole ratio, has been successfully developed using AlCl3·6H2O, Al2(SO4)3·18H2O and Na2CO3 as raw materials. The coagulation performance of PACS for removing natural organic matter (NOM) from surface water was evaluated, and the effect of SO42–/Al3+ mole ratio and γ value in coagulants PACS on DOC and UV254 removal was determined. Furthermore, the influence of pH and dosage of the selected PACS with a SO42–/Al3+ ratio of 0.0664 and a γ value of 2.0, which achieved the best coagulation performance for the removal of DOC and UV254 of all PACS coagulants, on the removal of DOC and UV254 and residual aluminum concentration in treated water was investigated. The results were compared with the ones of polyaluminum chloride (PAC) with γ value of 2.0. The experimental data show that the performance of PACS as a coagulant was highly dependent on SO42–/Al3+ mole ratio and γ value. Both for the selected PACS and for PAC, the best DOC and UV254 removal results were obtained in the range of pH from 5.0 to 8.2 and at the coagulation dose of 5.0 mg/L as Al. Under the optimum coagulation conditions, the selected PACS gave higher DOC and UV254 removal efficiencies, and lower residual aluminum concentrations in the treated water than PAC. The maximum removal of DOC and UV254 for PACS was approximately 88.0% and 93.0%, respectively. At the optimum coagulant dose and pH 6.5, the concentration of residual aluminum in treated water by both selected PACS and PAC can comply with the regulated limits. The major mechanisms of NOM removal by PACS and PAC coagulation involve complexation‐charge‐neutralization‐precipitation. 相似文献
993.
大同地震台地电阻率变化与震兆特征 总被引:1,自引:0,他引:1
殷志刚 《地震地磁观测与研究》2006,27(B08):22-27
以大同地震台地电阻率18年的观测资料为依据,研究了台站周边300km以内5级以上地震和100km以内4级以上地震,对地电阻率资料异常变化形态与地震的关系进行了探讨,结果显示,其异常形态表现为年畸变、年变的消失、U型凹斗。其长期变化趋势为NS、NW向缓慢斜向上变化,EW向有一近12年正弦波形变化。异常与地震对应关系较好。 相似文献
994.
995.
1 INTRODUCTION 1. 1 Dam Removal The aging of the more than 75,000 dams in the U.S., coupled with the increasing awareness of their environmental costs, has made dam decommissioning and removal a topic of current interest to the scientific community, management agencies, and the general public. It is estimated that 85% of the dams in the U.S. will be near the end of their operational lives by the year 2020 (FEMA, 1999), necessitating thorough consideration of dam removal or repair for… 相似文献
996.
对东泰气田Jp^1气藏拟定的两套开发方案从投资估算、盈利能力等技术经济角度出发,对两套开发方案进行了技术经济评价和对比分析,得出两套开发方案中更加合理的开发方案,对东泰气田蓬一气藏的勘探与开发提供了技术经济指导。 相似文献
997.
998.
Karin Thomas Andreas Volz-Thomas Djuro Mihelcic Herman G. J. Smit Dieter Kley 《Journal of Atmospheric Chemistry》1998,29(1):17-43
The exchange of NO3 radicals with the aqueous-phase was investigated at room temperature (293 K) in a series of wetted denuders. From these experiments, the uptake coefficient of NO3 was determined on 0.1 M NaCl solutions and was found to be (NO3) 2 × 10-3 in good agreement with recent studies. The Henry coefficient of NO3 was estimated to be KH(NO3) = 1.8 M · atm-1, with a (2) uncertainty of ±3 M · atm-1. From the upper limit for the Henry coefficient (KH = 5 M · atm-1) and available thermodynamic data, the redox potential of dissolved NO3/NO
3
–
is estimated to be in the range of 2.3 to 2.5 V. This range is at the lower boundary of earlier estimates. The results are discussed in the light of a recent publication. Based on our data and a model of the transport and chemistry in the liquid film, an upper limit is derived for the product of the Henry coefficient KH and the rate coefficient k
10 of the potential reaction NO3 + H2O HNO3 + OH. For KH = 0.6 M · atm-1, we find k
10 < 0.05 s-1 · atm-1, i.e., about 100 times smaller than what was suggested by Rudich and co-workers. Because of its small solubility, heterogeneous removal of NO3 is only important under conditions where the dissolved NO3 is removed quickly from equilibrium, for example by reactions with Cl– or HSO
3
–
ions in the liquid-phase. Otherwise, heterogenous removal should mainly proceed via N2O5. 相似文献
999.
通过对水稻雄性不育的遗传分析,提出了雄性不育“质、核互作诱导’的遗传假说。并据此还提出采用“质、核双杂交”的方法来克服亚种间杂交不亲和性的设想,供探讨。 相似文献
1000.
半干喷雾法脱除燃煤锅炉烟气中硫、氮技术及装置 总被引:3,自引:0,他引:3
通过理论分析和试验研究发现,利用锅炉碱性排污水或化学碱性水对锅炉尾部烟道进行喷雾,可以达到脱除烟气中SOx、MOx的目的,并取得了良好效果。其技术关键是喷淋雾化方式、喷雾水量、喷雾水的碱度及烟道结构对气-汽两相流之间混合湍动的影响。该方法具有投资少、运行费用低、运行简单可靠、脱硫脱氮效果好、不产生二次污染和烟道阻力及腐蚀小等特点。针对我国燃煤锅炉量大、面广、分散的特点,该方法具有广阔的应用前景。 相似文献