Humic acid protein complexation

Interactions of purified Aldrich humic acid (PAHA) with lysozyme (LSZ) are investigated. In solution LSZ is moderately positively and PAHA negatively charged at the investigated pH values. The proton binding of PAHA and of LSZ is determined by potentiometric proton titrations at various KCl concentrations. It is also measured for two mixtures of PAHA-LSZ and compared with theoretically calculated proton binding assuming no mutual interaction. The charge adaptation due to PAHA-LSZ interaction is relatively small and only significant at low and high pH. Next to the proton binding, the mass ratio PAHA/LSZ at the iso-electric point (IEP) of the complex at given solution conditions is measured together with the pH using the Mütek particle charge detector. From the pH changes the charge adaptation due to the interaction can be found. Also these measurements show that the net charge adaptation is weak for PAHA-LSZ complexes at their IEP. PAHA/LSZ mass ratios in the complexes at the IEP are measured at pH 5 and 7. At pH 5 and 50 mmol/L KCl the charge of the complex is compensated for 30-40% by K⁺; at pH 7, where LSZ has a rather low positive charge, this is 45-55%. At pH 5 and 5 mmol/L KCl the PAHA/LSZ mass ratio at the IEP of the complex depends on the order of addition. When LSZ is added to PAHA about 25% K⁺ is included in the complex, but no K⁺ is incorporated when PAHA is added to LSZ. The flocculation behavior of the complexes is also different. After LSZ addition to PAHA slow precipitation occurs (6-24 h) in the IEP, but after addition of PAHA to LSZ no precipitation can be seen after 12 h. Clearly, PAHA/LSZ complexation and the colloidal stability of PAHA-LSZ aggregates depend on the order of addition. Some implications of the observed behavior are discussed.     

Assessment of the quantitative and qualitative buffer function of an alluvial wetland: hydrological modelling of a large floodplain (Garonne River,France)

For 2 years, water flow‐patterns in the Garonne floodplain of south‐western France were studied in the field and through hydrodynamic modelling (MARTHE Hydrodynamic Software developed by BRGM). Water flow‐paths and the transport of dissolved elements between river and aquifer have been investigated and modelled. In order to quantify the buffer function of the alluvial floodplain, we focused our work on the effect of a major flood on the water flow‐direction, and on nitrate transport. Thus, we showed that the effect of a large flood in the river was rapidly lost with increasing distance from the river. During the observation period, a hydrologically active strip only 300 m wide on either side of the riverbed played a buffering role in absorbing the flood crest. It was also found that meanders favour the exchange between river and alluvial aquifer, shown by the creation of bypasses between the upstream and downstream parts of meanders. This, in turn, contributes to a dilution of nitrates in the phreatic aquifer, which here has higher nitrate content than the surface water; such dilution may result in an overestimation of the denitrification process in the wooded riverbanks. The coupling of chemical measurements—especially of chlorides and nitrate—with modelling of the dissolved‐element transport allows us to establish the water balance for the riparian wetland, and to separate the effect of dilution and denitrification on nitrate concentration. This indicated the existence of areas in the riparian wetlands where denitrification is particularly strong, leading to reductions in nitrate concentrations of 10 to 30 mg/l NO₃^? during the flood. Copyright © 2003 John Wiley & Sons, Ltd.     

Occam's inversion of magnetic resonance sounding on a layered electrically conductive earth

The magnitudes of the initial amplitude of the magnetic resonance sounding (MRS) signals from an aquifer located in a layered electrically conductive earth, are nonlinear functions of water content distribution. Occam's inversion method is adapted to the nonlinear inversion problem. In the case of an electrically conductive medium, the Jacobian matrix is analytically evaluated at the beginning of the inversion. And the uniqueness of the inversion can be partially solved by imposing the flattest and smoothest model constraints on the optimization problem. Synthetic MRS signals from resistive and conductive earth, as well as field data, have been inverted by Occam's method. The results indicate that with the help of Occam's inversion, a true model can be obtained from an initial model of homogeneous water content. Furthermore, for noise-free MRS signals, both the flattest and smoothest models reveal correct water content distributions. When signals are contaminated by noises, the case is different; and the smoothest model might have a lower water content distributing in a larger range than that of the true model, while which might be obtained by utilizing the flattest model Occam's inversion.     

琼州海峡南北海岸带大风的天气气候特征

根据最大风、极大风两种大风事件标准,利用琼州海峡南北沿岸海口、琼山、临高、徐闻4站1977-2006年地面观测资料,分析了琼州海峡南北海岸带大风的天气气候特征,并对大风形成的可能机制进行了探讨.近30年,琼州海峡南北两岸大风日数的演变趋势不同,北岸具有波动的演变规律,具有14年的年代际变化周期和2～4年的年际变化周期,波动周期与影响海南岛的热带气旋年频数的显著周期基本一致;南岸为线性减少趋势,气候突变期为20世纪90年代中后期.城市化进程加快、冷空气势力减弱是导致南岸大风事件显著减少的主要原因.北岸易出现东北大风,南岸易出现偏南大风;平均而言,南岸大风强于北岸,两岸大风均以夏季出现频率最高,冬季最少,这与我国大部分地区大风的季节特征不同.     

基于球坐标系下有限差分的地磁测深三维正演

为了计算全球尺度电磁感应的响应,本文介绍地磁测深频率域三维正演。正演算法采用球坐标系下的交错网格有限差分方法,从Maxwell方程的积分形式出发,采用PARDISO对离散后的方程组求解,避免了迭代求解的散度校正。为了验证本文结果的正确性和精度,与前人的有限元和有限差分方法进行了对比,一维层状模型的三维交错网格有限差分数值结果和解析解相对误差小于5%,双半球模型的计算结果与前人的计算结果完全吻合。三维"棋盘模型"计算表明磁场分量对异常体的大小和位置具有很好的分辨能力。     

The Influences of Geological History,Climatic Variations and the Environment Changes on the Terrestrial Biodiversity of Sunda Region

Sunda region, located in the tropical region of Southeast Asia, is one of the three main regions of the tropical rainforests with the highest biodiversity in the world, and also the most endangered ranges of species extinction. The high biodiversity in the region was due to several reasons: ①the lucky geographical location in the warm and moist tropics, ②joint zone between the two large tectonic plates Eurasia and India-Australia, ③with abundant of islands separated with different distances. ④In the cycles of glacial-interglacial during the geological history, the variations of the temperature and the fluctuations of the sea level created opportunities for the species interactions and gene mixture, therefore resulting in the formation of new species and contributing more species to the region. In particular, during Quaternary period, the continental shelves exposed repeatedly during the glacial times, and the many islands were often merged into one or a few continuous and large territories, making the gene flows within species easier. During the interglacials, the sea-level rose and the continental shelved were submerged, and the scattered and isolated territories might make the speciation and extinction occurred more frequently. Biological refugia might be important for many species’ survival. Today, with the rapid global warming and intensive human disturbance, the refugia may be more crucial for many species to survive. However, the extinction of many species may be inevitable.     

深海海面目标单水听器被动测距方法与验证

基于射线理论分析了在深海情况下海面声源产生声场的频率-距离干涉结构,给出了影区内声场频率-距离干涉结构的近似理论表达式,分析得到影区内声场频域干涉周期随收发距离的增加而增大、随着接收水听器深度的增加而减小。因此由单水听器记录的声场干涉结构即可实现被动声源距离估计。在南海深海实验中观测到海面宽带噪声源在声场影区形成的声场干涉结构,对实验获得声场干涉结构的处理结果验证了深海声场影区干涉结构用于被动声源距离估计的有效性。与传统的匹配场被动定位方法相比,该方法不需要已知海底声学参数和大规模的拷贝场计算。     

2011夏季南极普里兹湾营养盐与浮游植物生物量的分布

利用2011南极夏季在普里兹湾获取的海水样,检测了Chla、磷酸盐、硅酸盐、硝酸盐和铵盐的含量。结果表明,普里兹湾表层海水中Chla的含量普遍具有冰架边缘>陆架区>陆坡及深海区的分布特征,海冰的消融及水体的稳定性是影响表层海水Chla分布的主要原因。Chla含量的垂直分布与光照条件相关,具有上层水体含量高,随着深度逐渐降低的分布特征。磷酸盐、硅酸盐和硝酸盐的水平及垂直分布特征都与Chla的分布格局相反。表层海水中铵盐的分布特征与磷酸盐等主要营养盐的分布格局相反,冰架边缘、陆架区铵盐的垂直分布特征与陆坡及深海区不同,在冰架边缘和陆架区有机质降解过程主导着水柱中铵盐的浓度,而浮游植物吸收作用与有机质降解过程之间的平衡控制着陆坡及深海区铵盐的垂直分布。根据Chla与营养盐的浓度及分布特征,结合温度、盐度、溶解氧等水文要素,分析探讨了Chla深层最大值现象（DCM）的成因及67.5°S以南表层海水中铵盐对硝酸盐吸收的抑制作用。     

浙江黄岩富山地区古崩塌地貌发育机制

利用野外综合考察和岩石样品的室内分析资料,对浙江黄岩富山地区古崩塌地貌发育机制进行了研究。结果表明研究区自晚侏罗世以来经历了火山沉积和岩浆侵入阶段,形成花岗斑岩。新构造运动使本区发生间歇性抬升,岩石受构造应力和风化剥蚀的共同影响,形成多组垂直节理和水平节理。本区特定的地貌、岩性和节理裂隙以及丰富的降水和风化作用等条件,形成了一线天、陡崖壁、嶂谷、峡谷、巷谷、瀑布、巨石川、崩塌岩洞等古崩塌地貌。     

Glacial atmospheric CO2 decline in association with decrease of marine sedimentary phosphorus

The environmental and biogeochemical information extracted from the sediments collected from the northern shelf of the South China Sea shows that terrigenous inputs of phosphorus into the sea remained relatively constant, and the variation of phosphorus contents at different depths was caused by climatic and environmental changes. The findings also suggest that the vertical variation of phosphorus content was opposite to those of calcium carbonate and cadmium, and the functional correlation between CO₂ and PO ₄ ³⁻ in seawater was given by calculating the chemical equilibrium, indicating that the accumulation of marine sedimentary phosphorus may have something to do with the variation of atmospheric CO₂. The decreased phosphorus accumulation as well as the correspondingly-increased calcium carbonate content might be one of key factors causing glacial atmospheric CO₂ decline.