Assessment of groundwater pollution around Torbali,Izmir, Turkey     

A. O. Aksoy  T. Scheytt 《Environmental Geology》2007,53(1):19-25

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   

Preparation and evaluation of polyaluminum chloride sulfate (PACS) as a coagulant to remove natural organic matter from water     

Bao Yu Gao  Gudrun Abbt‐Braun  Fritz H. Frimmel 《洁净——土壤、空气、水》2006,34(5):491-497

A series of polyaluminum chloride sulfate (PACS) coagulants, which have different SO₄^2–/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 SO₄^2–/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 SO₄^2–/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 SO₄^2–/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   

PREDICTING THE DEPTH OF EROSION IN RESERVOIRS FOLLOWING DAM REMOVAL USING BANK STABILITY ANALYSIS     

Martin W. DOYLE  Emily H. STANLEY  Andy R. SELLE  John M. STOFLETH  Jon M. HARBOR 《国际泥沙研究》2003,18(2)

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   

华北克拉通岩石圈地幔置换作用和壳幔生长耦合的Re-Os同位素证据   总被引：27，自引：2，他引：27  

高山  刘勇胜 《地学前缘》2003,10(3):61-67

测定了辽宁复县奥陶纪金伯利岩和河北汉诺坝与山东栖霞第三纪碱性玄武岩中产出的地幔包体的Re Os同位素组成。金伯利岩中地幔包体的Re贫化Os同位素模式年龄 (TRD)为 2 .5～ 2 .8Ga ,从Re Os同位素定年角度证明了华北克拉通确实存在太古宙岩石圈地幔。对汉诺坝二辉橄榄岩包体获得了 (1.9± 0 .18)Ga的Re Os同位素等时线年龄 ,表明现今保存在那里的地幔主要是古元古代时形成的。汉诺坝地区出露有大量新太古代岩石 ,表明曾存在太古宙地幔。由于缺乏太古宙年龄 ,说明由汉诺坝所代表的克拉通中部曾存在的太古宙地幔在古元古代时已被减薄 ,并被 1.9Ga的新生岩石圈地幔置换。该事件与华北克拉通中部广泛的古元古代碰撞造山过程导致的麻粒岩相变质作用的时代相同 ,说明有关的岩石圈置换作用可能主要与拆沉作用有关。栖霞地幔包体具有与现代对流地幔相同的Os同位素组成 ,且Os同位素组成与Re/Os比值没有明显相关性 ,表明年龄很新。结合其它地质地球化学证据 ,说明克拉通东部的太古宙岩石圈地幔的置换作用主要发生在中生代 ,且可能与三叠纪华北和扬子陆块的陆陆碰撞造山导致的岩石圈地幔和下地壳的拆沉作用有关。本研究表明华北克拉通岩石圈地幔置换作用在时空上的分布是十分不均一的。 2 .5～ 2 .8Ga与 1.9Ga不仅?  相似文献   

炉渣处理含磷废水的实验研究   总被引：9，自引：0，他引：9       下载免费PDF全文

邓雁希 许虹黄玲  钟佐燊 《岩石矿物学杂志》2003,22(3):290-292

以炉渣作为吸附剂，用静态吸附实验方法研究了炉渣对模拟含磷废水脱磷的一般规律，结果表明，炉渣是一种有效的吸附剂，对废水中的磷有较强的吸附去除性能。影响炉渣除磷的主要因素有吸附时间、炉渣用量、pH值和原水含磷浓度。在含磷浓度2～13mg／L、炉渣用量5g／L、中性、吸附时间为2h的实验条件下，磷的去除率可高达99％以上。  相似文献   

On the Exchange of NO3 Radicals with Aqueous Solutions: Solubility and Sticking Coefficient     

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 K_H(NO₃) = 1.8 M · atm^-1, with a (2) uncertainty of ±3 M · atm^-1. From the upper limit for the Henry coefficient (K_H = 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 K_H and the rate coefficient k ₁₀ of the potential reaction NO₃ + H₂O HNO₃ + OH. For K_H = 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   

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  

杨向民 《煤田地质与勘探》1998,(Z1)

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   

污染河道对沿岸地下水环境影响规律研究   总被引：8，自引：1，他引：8       下载免费PDF全文

王超  李勇  包振琪 《水科学进展》2002,13(5):535-541

以江苏奎河为例,观测研究奎河污染物COD_Cr、NH₄+-N、NO₃--N、Cl-入渗进入地下水中发生物理、化学及生物变化的时空分布规律,分析河道沿岸土壤对污染物的去除能力.结果表明:河床的土壤对污染物COD_Cr具有很高的去除率,对NH₄+-N亦有较高的去除率.河道中的NO₃--N在入渗过程中虽有一定的去除率,但由于NH₄+-N、NO₂--N等污染因子转化成NO₃--N,因此该浓度不一定会明显降低.Cl-是保守性污染因子,入渗过程中虽有一定的去除率,但仍对沿岸地下水环境产生影响.因此,当污染河道中污染因子是保守性物质时,必须考虑对沿岸地下水源地的影响.  相似文献   

On the wet removal of gaseous and particulate sulfur and nitrogen species from the atmosphere     

E. Mészáros  T. Szentimrei 《Journal of Atmospheric Chemistry》1985,2(4):405-413

The role of trace gases and aerosol particles in the control of sulfur and nitrogen levels in atmospheric precipitation is estimated on the basis of the enrichment factor in the precipitation of these elements relative to particulate matter in the air. By using air and precipitation chemistry data obtained at a Hungarian background air pollution station (K-puszta) it is found that the fraction of ammonium, nitrate and sulfate in precipitation, due to the removal of particulate matter is at least 59, 27 and 31%, respectively. The relationship between wet depositions and air concentrations of different species is determined statistically by applying daily data set. The regression equations obtained make the estimation of the sub-cloud scavenging ratios possible and they give some information on the magnitude of in-cloud scavenging processes. The results show that the in-cloud scavenging is a determining factor for precipitation sulfate, while it is relatively unimportant in the case of ammonium. The sub-cloud scavening of NO₂ and SO₂ is not too significant. However, for HNO₃, and NH₃ it is an effective process. The sub-cloud scavenging ratio of sulfur and nitrogen-containing particles varies around 0.25×10⁶.  相似文献   

The application of erosion slowness theory to hillslope formation     

G. Carter  M. J. Nobes 《地球表面变化过程与地形》1980,5(2):131-141

A method of analysis for predicting the time development of hillslope profiles is presented. The technique is based upon the assumption of weathering limited erosion and assumes that the local surface normal erosion rate is dependent upon the local flux of erosional agent and a function of the local slope gradient. This technique has been previously applied with success to analogous erosional processes in the sand blasting, chemical and energetic atom bombardment induced ablation of solids. The analysis shows how linearly segmented profiles can develop from initially curved surfaces and indicates the progress of profiles to stable end forms. Actual application to geomorphological situations is limited by lack of knowledge of micro-environmental erosion fluxes and the gradient dependence of erosion and it is suggested that field observations and laboratory simulations could be helpful in determining the utility of the analysis technique outlined here.  相似文献