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为研究降水补给地下水过程中包气带岩土对水化学的影响,在沂源地区采集了不同地表岩土样品开展淋溶和浸泡试验。淋溶结果显示:易溶的Cl~-、SO_4~(2-)、CO_3~(2-)、NO_2~-、NO_3~-等阴离子率先溶解进入淋溶水中,之后K~+,Ca~(2+),Mg~(2+),Fe等含量逐渐增加,且淋溶初期p H值呈碱性,之后向中性过渡。浸泡结果显示:不同类型岩土样经过浸泡5min后,其水化学组分发生了显著变化;随浸泡时间增加,K~+、Na~+、Ca~(2+)、Mg~(2+)、HCO_3~-及含盐量均出现不同程度增加,但Cl~-、SO_4~(2-)在不同类型岩土中含量变化则是不同的。由此推测,降水转入地下水过程中,透过地表浅层包气带时就已经淋溶了大量物质,水化学性质发生了重大变化。 相似文献
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To investigate the effect of recharge water temperature on bioclogging processes and mechanisms during seasonal managed aquifer recharge (MAR), two groups of laboratory percolation experiments were conducted: a winter test and a summer test. The temperatures were controlled at ~5±2 and ~15±3 °C, and the tests involved bacterial inoculums acquired from well water during March 2014 and August 2015, for the winter and summer tests, respectively. The results indicated that the sand columns clogged ~10 times faster in the summer test due to a 10-fold larger bacterial growth rate. The maximum concentrations of total extracellular polymeric substances (EPS) in the winter test were approximately twice those in the summer test, primarily caused by a ~200 μg/g sand increase of both loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). In the first half of the experimental period, the accumulation of bacteria cells and EPS production induced rapid bioclogging in both the winter and summer tests. Afterward, increasing bacterial growth dominated the bioclogging in the summer test, while the accumulation of LB-EPS led to further bioclogging in the winter test. The biological analysis determined that the dominant bacteria in experiments for both seasons were different and the bacterial community diversity was ~50% higher in the winter test than that for summer. The seasonal inoculums could lead to differences in the bacterial community structure and diversity, while recharge water temperature was considered to be a major factor influencing the bacterial growth rate and metabolism behavior during the seasonal bioclogging process. 相似文献
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We present a special solar radio burst detected on 5 January 1994 using the multi-channel (50) spectrometer (1.0–2.0 GHz) of the Beijing Astronomical Observatory (BAO). Sadly, the whole event could not be recorded since it had a broader bandwidth than the limit range of the instrument. The important part was obtained, however. The event is composed of a normal drift type III burst on the lower frequency side and a reverse drift type III burst appearing almost simultaneously on the high side. We call the burst type III a burst pair. It is a typical characteristic of two type III bursts that they are morphologically symmetric about some frequency from 1.64 GHz to 1.78 GHz on the dynamic spectra records, which indicates that there are two different electron beams from the same acceleration region travelling simultaneously in opposite directions (upward and downward). A magnetic reconnection mode is a nice interpretation of type III burst pair since the plasma beta 0.01 is much less than 1 and the beams have velocity of about 1.07×108 cm s–1 after leaving the reconnection region if we assume that the ambient magnetic field strength is about 100 G. 相似文献
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We analyze the high-frequency drift radio structures observed by the spectrometer at Purple Mountain Observatory (PMO) over
the frequency range of 4.5 – 7.5 GHz during the 18 March 2003 solar flare. The drifting structures take place before the soft
X-ray maximum, almost at the maximum of hard X-ray flux at 25 – 50 keV. For the first time, the positive drift in this kind
of radio structures is detected in such a high frequency range. Their global drifting rate is roughly estimated as 3.6 GHz s−1. They appear in four groups, lasting in total for less than 6 s, and have a broad bandwidth of more than 2 GHz but a smaller
ratio of the bandwidth of the drifting structures to mean frequency than that of the lower frequency range. The lifetime of
each individual burst in this event can be derived by using the high temporal resolution of the spectrometer at PMO and has
an average value of 36.3 ms. Since the negative drifting structures observed in the 0.6 – 4.5 GHz frequency range were interpreted
to be a radio signature of a plasmoid ejected upward (moving out of the Sun), the present observation may imply that it is
possible for a plasmoid to move downward during a solar flare. However, for a confirmation of this suggestion direct radio
imaging observation would be needed. 相似文献
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We explore the hard X-ray source distributions of an C1.1 flare occurred on 14 December 2007. Both Hinode/EIS and RHESSI observations are used. One of EIS rasters perfectly covers the double hard X-ray footpoints, where the EUV
emission appears strong from the cool line of He ii (log T=4.7) to the hot line of Fe xvi (log T=6.4). We analyze RHESSI X-ray images at different energies and different times before the hard X-ray maximum. The results
show a similar topology for the time-dependent source distribution (i.e. at 14:14:35 UT) as that for energy-dependent source distribution (i.e. at a given energy band of 6 – 9 keV) overlapped on EUV bright kernels, which seems to be consistent with the evaporation
model. 相似文献
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Zongjun Ning 《Solar physics》2014,289(4):1239-1256
Quasi-periodic oscillations in soft X-rays (SXR) are not well known due to the instrument limitations, especially the absence of imaging observations of SXR oscillations. We explore the quasi-periodic oscillations of SXR at 3?–?6 keV in a solar flare observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) on 26 December 2002. This was a B8.1 class event and showed three X-ray sources (S1, S2, and S3) at 3?–?6 keV and two sources (S1 and S2) at 12?–?25 keV. The light curves of the total fluxes display a two-minute oscillation at 3?–?6 keV, but not in the energy bands above 8 keV. To investigate imaging observations of the oscillations, we prepared CLEAN images at seven energy bands between 3 keV and 20 keV with an eight-second integration. The light curves of three sources were analyzed after integrating the flux of each source region. We used the Fourier method to decompose each source light curve into rapidly varying and slowly varying components. The rapidly varying components show seven individual peaks which are well fitted with a sine function. Then we used the wavelet method to analyze the periods in the rapidly varying component of each source. The results show that three sources display damped quasi-periodic oscillations with a similar two-minute period. The damped oscillations timescale varies between 2.5 to 6 minutes. Source S1 oscillates with the same phase as S3, but is almost in anti-phase with S2. Analyzing the flaring images in more detail, we found that these oscillation peaks are well consistent with the appearance of S3, which seems to split from or merge with S2 with a period of two minutes. The flare images with a high cadence of one second at 3?–?6 keV show that source S3 appears with a rapid period of 25 seconds. The two-minute oscillation shows the highest spectral power. Source S3 seems to shift its position along the flare loop with a mean speed of 130 km?s?1, which is of the same order as the local sound speed. This connection between the oscillation peaks and emission enhancement appears to be an observational constraint on the emission mechanism at 3?–?6 keV. 相似文献
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Zongjun Ning M. D. Ding K. P. Qiu H. Li Y. N. Su C. Fang 《Astrophysics and Space Science》2008,315(1-4):45-51
We present multi-wavelength observations of a complicated solar eruption event to associate with an X1.2 flare and a Coronal Mass Ejection (CME) on 2003 October 26. The soft X-ray profile shows a possibility for occurrence of two flares with peaks around 06:20 and 07:00 UT. According to our observations, there are many evidences to show that they are corresponding to two energy releases. The first one produces type II, type III, moving type IV continua, a decimetric burst (DCIM) and strong emissions at Hα, 195 and 1600 Å; While the second energy release only produces a group of RS-III bursts, DCIM and Hα emissions. It appears that the first energy release is associated with a CME, while the second CME is quiet. Such observational difference between two energy releases is found indicating two magnetic reconnection processes occurrence with different plasma situation. 相似文献
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Zongjun Ning 《Solar physics》2008,248(1):99-111
Previous observations show that in many solar flares there is a causal correlation between the hard X-ray flux and the derivative
of the soft X-ray flux. This so-called Neupert effect is indicative of a strong link between the primary energy release to
accelerate particles and plasma heating. It suggests a flare model in which the hard X-rays are electron – ion bremsstrahlung
produced by energetic electrons as they lose their energy in the lower corona and chromosphere and the soft X-rays are thermal
bremsstrahlung from the “chromospheric evaporation” plasma heated by those same electrons. Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observes in a broad energy band and its high spectral resolution and coverage of the low-energy range allow us to
separate the thermal continuum from the nonthermal component, which gives us an opportunity to investigate the Neupert effect.
In this paper, we use the parameters derived from RHESSI observations to trace the primary energy release and the plasma response:
The hard X-ray flux or spectral hardness is compared with the derivative of plasma thermal energy in three impulsive flares
on 10 November 2002 and on 3 and 25 August 2005. High correlations show that the Neupert effect does hold for the two hard
X-ray peaks of the 10 November 2002 flare, for the first peaks of the 3 August 2005 flare, and for the beginning period of
the 25 August 2005 flare. 相似文献
10.
雅鲁藏布江丰水期河水离子组成特征及其控制因素 总被引：1，自引：0，他引：1
为了解雅鲁藏布江丰水期河水离子组成特征及其控制因素,利用2015年采集的8个河水水样,运用数理统计、聚类分析、Piper三线图、Gibbs模型以及离子比值等方法,分析了雅鲁藏布江丰水期河水水化学特征,并探讨了其主要控制因素。结果表明：河水中阳离子以Ca2+、Mg2+为主,阴离子则以HCO3-和SO42-为主,阴、阳离子分别约占其总量的96%和85%。河水水化学类型均为HCO3·SO4-Ca·Mg型。TDS含量介于202.46~371.27 mg·L-1,均值为299.30 mg·L-1,较世界河流平均值高。自上至下,河水水化学特征表现出一定的差异性,河水中主要离子以及TDS、TH、EC的含量沿程表现出下降的趋势,其原因主要有支流河水汇入和降水增加的稀释作用。河水水样均落在Gibbs模型图中部偏左,表明河水中主要离子化学组分主要受水岩作用控制。离子比值法分析表明研究区碳酸盐岩以及蒸发岩的风化溶解是河水水化学的主要控制因素,且存在硅酸盐类矿物的风化。 相似文献