曝气和pH对城市污染河道底泥氮形态的影响

以城市重污染河道表层沉积物为研究对象,采用模拟实验方法,探讨了不同曝气方式(水曝气和泥曝气)、上覆水初始pH(自然状态pH=7和pH=11)对城市污染河道底泥氮形态的影响。结果表明:采用水曝气+pH11方式对城市重污染河道上覆水、间隙水中总氮去除率分别为70.03%和44.66%;泥曝气+pH7方式对上覆水、间隙水、底泥中氨氮去除率分别为94.31%、84.07%和68.29%;底泥pH与上覆水总氮浓度呈正相关(p<0.05);泥曝气+pH11方式使底泥含水率、烧失率明显升高,继而影响各形态氮在泥水系统中的赋存,其中底泥吸附态氨氮含量与底泥含水率呈显著负相关(p<0.01),间隙水可溶态氨氮浓度与底泥烧失率显著正相关(p<0.01)。     

气体扩散电极在水处理领域中的研究进展

气体扩散电极（Gas Diffusion Electrode—GDE）作为阴极,通过氧气还原产生过氧化氢（H202）,在亚铁离子催化剂存在的情况下形成Fenton试剂,从而间接氧化有机污染物,这方面的研究逐步引起人们的重视。本文综述了电极材料、电流密度、pH、催化剂等因素对处理效果的影响,提出了该方法存在的问题并对其发展趋势进行了展望。     

Variability of soil-water quality due to Tsunami-2004 in the coastal belt of Nagapattinam district, Tamilnadu

In this study, the Tsunami-caused deterioration of soil and groundwater quality in the agricultural fields of coastal Nagapattinam district of Tamilnadu state in India is presented by analyzing their salinity and sodicity parameters. To accomplish this, three sets of soil samples up to a depth of 30cm from the land surface were collected for the first six months of the year 2005 from 28 locations and the ground water samples were monitored from seven existing dug wells and hand pumps covering the study region at intervals of 3 months. The EC and pH values of both the soil and ground water samples were estimated and the spatial and temporal variability mappings of these parameters were performed using the geostatistical analysis module of ArcGIS((R)). It was observed that the spherical semivariogram fitted well with the data set of both EC and pH and the generated kriged maps explained the spatial and temporal variability under different ranges of EC and pH values. Further, the recorded EC and pH data of soil and ground water during pre-Tsunami periods were compared with the collected data and generated variability soil maps of EC and pH of the post-Tsunami period. It was revealed from this analysis that the soil quality six months after the Tsunami was nearing the pre-Tsunami scenario (EC< 1.5dSm(-1); pH<8), whereas the quality of ground water remained highly saline and unfit for irrigation and drinking. These observations were compared with the ground scenarios of the study region and possible causes for such changes and the remedial measures for taking up regular agricultural practices are also discussed.     

pH、温度和水土比对酸性土壤溶液中铝离子形态分布的影响

溶液中Al3 、Al-F和有机络合态铝（Al-OM的浓度随pH降低而增加,Al3 在总单核铝中所占比例随pH的降低而增加,而Al-F络合物呈相反的变化趋势.土壤中铝的溶解度与土壤中铝氧化物的结晶形态有关,处于较高纬度地区的土壤,由于铝氧化物的结晶形态较差,在相同pH下,其铝的溶解度较大.土壤溶液中有机络合态铝的浓度随温度升高而增加,在pH不变的情况下,土壤中无机铝的溶解量随温度降低而增加.随水土比增加,土壤溶液中Al3 、Al-F络合物和Al-OM浓度减小,但按每kg土计算的铝溶解量随水土比的增加而增加.     

海洋纤毛虫——巨大拟阿脑虫的实验生态研究Ⅲ.pH对种群生长的影响

就水环境中pH对巨大拟阿脑虫Paranophys magna（纤毛门,盾纤目）种群生长的影响及后者的应答与适应进行了探讨,结果表明,虫体生存的pH阈值约为5－9．6,最适范围为7.0-9.0;pH对巨大拟阿脑虫的种群生长有显著影响,种群自然增长率及种群所达最大种群密度均随pH的不同而明显改变。     

活性炭纤维处理腐植酸废水

采用活性碳纤维处理腐植酸模拟废水,通过静态吸附和动态吸附的研究,测定吸附等温线和动态吸附曲线;研究不同温度、不同活性炭纤维、不同pH值和流速对处理效果的影响。     

VPT511BF-SY多孔流速仪在烟气流量在线监测中的应用

针对目前国内基于单个探头的单点在线测试烟气流量与参比方法监测比对合格率不高的问题,提出一种新颖的基于平均差压皮托管法的多孔流速仪,通过对不同的安装位置及安装数量的多孔烟气流速仪的烟气在线流量监测结果与手工监测结果进行比对,验证在适当位置安装一定数量的多孔烟气流速仪可以确保与手工监测比对结果满足要求。     

pH值调控柠檬酸污泥厌氧发酵产酸及碳源潜力研究

以柠檬酸废水厌氧颗粒污泥为接种物,在不同pH值调控条件下开展柠檬酸生产废水剩余活性污泥厌氧发酵产酸研究.通过对发酵液挥发性脂肪酸(VFAs)、有机质、氮磷和污泥脱水性能的分析,探讨了柠檬酸污泥厌氧产酸机制.结果表明,pH≥10的碱性条件更有利于有机质的溶出从而促进VFAs的产生.三维荧光光谱分析发现在恒定pH值下腐殖酸(HA)和富里酸(FA)会大量溶出降低VFAs的产量.初始pH=10是柠檬酸污泥厌氧产酸的最佳p H值,发酵4d的VFAs浓度最高达(6681.47±126.82)mgCOD/L,是文献报道中市政污泥产酸量的近2倍,其中乙酸占比49.8%,发酵后产酸功能菌Chloroflexi、Bacteroidota的相对丰度分别由初始的9.52%、10.87%增至16.84%、14.39%,污泥归一化毛细吸水时间(nCST)为(11.34±0.27)s·L/g,脱水性能良好,发酵液TP浓度为(20.45±0.33) mg/L.研究表明,利用柠檬酸剩余活性污泥碱性厌氧发酵产酸作为污水处理过程中的外加碳源具有较大潜力.     

Experimental and theoretical studies on physico-chemical parameters affecting the solubility of phosphogypsum

Phosphogypsum is a waste by-product of the phosphate fertilizer industry, which is usually disposed in the environment because of its restricted use in industrial applications. Physico-chemical conditions existing in stack fluids and leachates are of major importance and determine solubility and redox stability of phosphogypsum, as well as radionuclide release from stacks to terrestrial environments. The aim of this study is to assess the effect of key parameters (e.g. ionic strength, temperature, pH) on the solubility of phosphogypsum. Phosphogypsum sampling and in-situ measurements were carried out at a coastal stack in Cyprus, solubility experiments were performed in simulated laboratory systems and thermodynamic calculations by means of MINTEQA2, an equilibrium speciation model. Generally, increasing ionic strength and temperature leads to increased phosphogypsum solubility, with the former being much more effective. The increased solubility of phosphogypsum in saline solutions is attributed solely to ionic strength effects on the activity of ionic species in solution and no solid phase transformations could be observed. The effect of pH on phosphogypsum solubility seems to be insignificant at least in a pH range between 4 and 8. Regarding uranium levels, there is a strong correlation between salinity and uranium concentration and linear correlation between phosphogypsum solubility and uranium levels in stack solutions, indicating the incorporation of uranium into the gypsum lattice and the formation of a solid solution.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.