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21.
Heike Sütterlin Rainer Trittler Sebastian Bojanowski Ernst A. Stadlbauer Klaus Kümmerer 《洁净——土壤、空气、水》2007,35(1):81-87
Thermocatalytic low temperature conversion (LTC) is a new method for the disposal of sewage sludge. Using this method, sludge is converted into a residual solid (coal) along with reaction water, oil, and non‐condensable gases. The oil can be used as an energy source and the coal as a substitute for charcoal. To this end, it is important to determine whether there are any easily available contaminants present in the coal generated by the process. Contaminants that can be strongly sorbed by sewage sludge solids are, e. g., pharmaceuticals and disinfectants. As an example the fate of the persistent and strong adsorbing disinfectant benzalkonium chloride (BAC) has been investigated within the LTC process. The sewage sludge was spiked with BAC and then subjected to the LTC process. The resulting coal was extracted and analyzed using LC‐LC/ESI‐MS/MS (ion trap). BAC could not be detected in the LTC coal, although it could be extracted from the spiked sludge before the LTC treatment. It can thus be concluded that the investigated compound is not easily available in the coal, and hence that its use does not present a risk. 相似文献
22.
选取了两种常见的沉水植物狐尾藻和金鱼藻,通过测定其单株生物量、株高、根生物量/单株生物量、茎生物量/单株生物量和叶生物量/单株生物量,研究这两种沉水植物在2 mg/L的铵态氮持续处理4 d以及铵态氮胁迫解除后的生长情况.结果表明:铵胁迫阶段,与对照组相比,处理对狐尾藻各测定参数均无显著影响,而使金鱼藻株高显著增加.在铵胁迫解除阶段,与对照组相比,处理组狐尾藻单株生物量增加不显著,而金鱼藻单株生物量显著增加;处理组2种沉水植物株高均显著增加;处理组狐尾藻叶生物量/单株生物量显著增加,而根生物量/单株生物量显著减少,茎生物量/单株生物量保持不变.认为高光照环境下(约400μmol/(m2·s)),水体中铵态氮浓度短时间内(4 d)适当增加对沉水植物生长没有抑制作用;金鱼藻对高铵态氮浓度水体的适应能力较狐尾藻强. 相似文献
23.
我国现行淡水水体中磷测定方法为钼酸铵分光光度法（GB 118931989）,该方法检测下限为0.01 mg/L,但我国南亚热带地区部分水体的总磷以及多数水体的溶解态磷浓度均低于0.01 mg/L,通过对标准试样和野外水样的测定,分析该方法在监测低磷浓度水体中可能出现的问题并提出改进方法.结果表明：对于磷浓度低于0.01 mg/L的水体,国标法灵敏度低,准确性差.通过3个方面的改进可提高该方法测定的灵敏度和准确性：1）将消解水样体积由25 ml增加到50 ml,消解后不再进行二次稀释定容;2）改变显色剂的配制,显色剂由14%硫酸溶液50 ml、酒石酸锑钾溶液5 ml、4%钼酸铵溶液15 ml和0.1 mol/L的抗坏血酸溶液30 ml混合而成,现配现用;3）将测定波长设置为880 nm.改进后方法的灵敏度有较大提高,能准确、有效地检测磷浓度在0.003~0.01 mg/L的水样. 相似文献
24.
M.J. WhitehouseA. Atkinson A.P. Rees 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(7):725-732
In this study we examined the hypothesis that, under conditions of replete macronutrients and iron in the Southern Ocean, phytoplankton abundance and specific N uptake rates are influenced strongly by the processes of grazing and NH4 regeneration. NH4 and NO3 uptake rates by marine phytoplankton were measured to the northeast and northwest of the island of South Georgia during January-February 1998. Mean specific uptake rate for NO3 (vNO3) was 0.0026 h−1 (range 0.0013-0.0065 h−1) and for NH4 (vNH4) was 0.0097 h−1 (0.0014-0.0376 h−1). vNH4 was related positively with NH4 availability, which ranged from 0.1 to 1.5 mmol m−3 within the upper mixed layer. Ambient NH4 concentrations and vNH4 were both positively related to local krill biomass values, computed from mean values along acoustic transect segments within 2 km of the uptake measurement stations. These biomass values ranged from ∼1 g krill fresh mass m−2 in the northwest to >4 kg krill wet mass m−2 in the northeast. In contrast to the variability found with NH4 concentrations and uptake rates, vNO3 was more uniform across the sampling sites. Under these conditions, increasing NH4 concentration appeared to represent an additional N resource. However, high vNH4 tended to be found for stations with lower phytoplankton standing stocks, across a total range of 0.24-20 mg chlorophyll a m−3. These patterns suggest a coupling between phytoplankton biomass, vNH4 and krill in this region of variable but high krill biomass. Locally high concentrations of krill in parts of the study area appeared to have two opposing effects. On the one hand they could graze down phytoplankton stocks, but on the other hand, their NH4 excretion supported enhanced uptake rates by the remaining, ungrazed cells. 相似文献
25.
M. Mookherjee M. D. Welch L. Le Pollès S. A. T. Redfern D. E. Harlov 《Physics and Chemistry of Minerals》2005,32(2):126-131
The behaviour of the ammonium ion in synthetic buddingtonite, N(D,H)4AlSi3O8, has been studied by infrared (IR) spectroscopy from 20 K to 298 K and by 2H NMR spectroscopy from 120 K to 298 K. IR spectra were collected from 500 to 3500 cm–1. Static 2H NMR spectra collected at 298 K and 120 K are very similar, consisting of a single sharp isotropic resonance, indicating complete averaging of quadrupolar interactions and implying that at these temperatures the ammonium ion is in rapid (<1 s) randomised motion within the M-site cavity of the feldspar framework. NMR spectroscopy indicates that the splitting of the internal modes of the ammonium ion observed by IR spectroscopy is not due to freezing in of the ammonium ion. This observation rules out the formation of a preferred N–H...O hydrogen bond, with precession of the ion about it, as proposed by Kimball and Megaw (1978), because any N–H...O hydrogen bond must be very weak and transient in nature. Contraction of the cavity site upon cooling imposes a distortion upon the ammonium ion that affects vibrational modes. This distortion does not affect the motion of the ammonium ion as observed on the NMR time-scale. 相似文献
26.
A. Yu. Likhacheva E. A. Paukshtis Yu. V. Seryotkin S. G. Shulgenko 《Physics and Chemistry of Minerals》2002,29(9):617-623
The IR spectrum of ammonium-exchanged natural analcime (basalt, Nidym River, Siberian platform) exhibits several features
that suggest a lowered symmetry for the NH4
+ ion and that this is influenced by hydrogen bonding within the framework. These features are: the pronounced splitting into
three components and high-frequency shift of the ν4-bending mode; appearance of the ν1-stretching mode which is predicted to become IR-active when the ideal T
d
symmetry of NH4
+ ion is violated, and the low-frequency shift of the ν1- and ν3-stretching modes. The absence of absorption lines in the 1800–2400-cm−1 region indicates that hydrogen bonding between the framework and the NH+
4 ion is very weak. The three-component splitting of the ν4-bending mode indicates that the symmetry of NH+
4 ion is lower than C3v. This implies that at least two N–H bonds of the NH+
4 ion are disturbed by hydrogen bonding. Computer analysis of the normal vibrations of the NH+
4 molecule for different symmetry types (using harmonic approximation) indicates that the best fit to the observed ν4 triplet frequencies for C1 symmetry implies a deviation of the valent angle ∠H–N–H from ideal T
d
symmetry of around ±2.5°. The factors governing the behaviour of the NH+
4 ion in the analcime structure are discussed. The geometry of the nearest environment of the NH+
4 ion in the analcime structure is analyzed with respect to the present IR data.
Received: 2 January 2002 / Accepted: 26 June 2002
Acknowledgements We thank Dr. D. Harlov and an anonymous reviewer for their helpful comments, as well as Dr. I.A. Belitsky and Dr. S.V. Goryainov
for discussion of the material. This work is supported by RFBR grants 01-05-65414, 00-05-65305 and 02-05-65313. 相似文献
27.
The infrared spectra and electron paramagnetic resonance (EPR) of channel constituents in beryls synthesized hydrothermally
in the presence of NH4Cl were investigated. Two forms of ammonium ion were observed to be incorporated into the c
-channel. IR-spectra show the double band at 3295 and 3232 cm−1 and two broad bands between 2600 and 3000 cm−1 which were assigned to the NH3 molecule and NH4
+ ion, respectively. Similar N–H stretching vibrations are also observed in Regency hydrothermal synthetic beryls and can be
used to separate these synthetic beryls from their natural counterparts. After γ-irradiation of hydrothermally grown samples
at 77 K, the EPR of the NH3
+(I) radical was observed. The NH3
+(II) radical replaces the NH3
+(I) radical when the sample is heated to room temperature. Both the NH3 molecule and the NH3
+ radical have their C3 symmetry axes perpendicular to the crystal c-axis. The spin Hamiltonian parameters of the NH3
+(I) are axial-symmetric due to the rapid rotation of the radical about the c-axis. The NH3
+(II) radical has a low symmetry and shows a hindered rotation because of its shift from the c-axis position and an interaction with the proton in the near neighbourhood. Possible models for the paramagnetic centres
are discussed.
Received: 16 May 2000 / Accepted: 5 July 2001 相似文献
28.
通过4个季节(1991年11月—1992年7月)的现场实验观测,初步研究了胶州湾表层浮游生物群落的NH_4~+-N吸收、再生通量的有关问题。结果表明,NH_4~+-N吸收、再生通量的季节变化为:夏季>春、秋季>冬季;周日变化为:吸收通量在白天大于夜间,再生通量夜间大于白天;全年平均,吸收通量为0.073μ mol/(L·h),再生通量为0.053μ mol/(L·h),再生通量始终小于吸收通量;NH_4~+-N的周转时间最长为16.34d(冬季),最短为0.68d(夏季);吸收通量主要来自Picoplankton(占总量的46％—57％);NH_4~+-N吸收具有光依赖性,不同粒级的光依赖顺序为:Netplankton>Nanoplankton>Picoplankton。 相似文献
29.
A method has been developed for the determination of ammonium concentration and isotopic enrichment in seawater samples at the low nanomolar range (10–100 nmol/kg). It is based on the reaction of phenol/hypochlorite with ammonium to form indophenol, with subsequent solid phase extraction, derivatisation and analysis by Gas Chromatography Mass Spectrometry. The precision of the method was maximised by incorporating a deuterated indophenol internal standard. A system was developed which generated seawater with extremely low ammonium concentrations thus matching sample and standard matrices for quantitative analysis. Data are presented from a study of ammonium regeneration rates at three stations in the oligotrophic North–East Atlantic where ambient ammonium concentrations were < 21 nmol/kg. Results suggested that ammonium availability for phytoplankton was limited by the rate of ammonium regeneration. Efficient ammonium assimilation contributed to the very low ambient ammonium concentrations measured at these stations. The study highlights the need for the accurate determination of ammonium regeneration rates in studies of new production, particularly in extreme oligotrophic conditions. If not corrected for isotope dilution, f-ratio estimates may be overestimated by 10.7–13.7%. 相似文献
30.
Ammonium release characteristics of the sediments from the shallow lakes in the middle and lower reaches of Yangtze River region,China 总被引：2，自引：0，他引：2
Juan Wang Shengrui Wang Xiangcan Jin Shuquan Zhu Fengchang Wu 《Environmental Geology》2008,55(1):37-45
Ammonium release from sediments has significant effects on the water quality in eutrophic lakes. In this study, the ammonium
release kinetics and adsorption–desorption processes were investigated in 13 sediments of 6 shallow lakes from the middle
and lower reaches of Yangtze River region, China. The results show that First Order Model best described the ammonium release
process, the maximal release capacity had a strong correlation with organic matter (OM), cationic exchange capacity (CEC),
total nitrogen (TN) and total phosphorus (TP). But it only had a weak correlation with Fe, Ca and Al. The ammonium release
capacity in more polluted sediments was higher than that in less polluted sediments. The average release rate within 0–5 min
was the highest among the experimental period, the amount released within 0–5 min accounted for approximately 50–70% of the
total release capacity. The ammonium release rate had a significant and positive correlation with OM. But it did not have
a strong correlation with TN, TP, Fe, Ca and Al. The ammonium potential release capacity (obtained when the water/sediment
ratio was about 2,500) had strong and positive relation with OM and maximal release capacity, and it may provide useful information
for the sediment release risk assessment. Henry Model best described the ammonium sorption isotherms, and ammonium adsorption–desorption
equilibrium concentration can be considered as the ammonium release threshold to assess the release risk in the sediments. 相似文献