Soil redox conditions and plant–soil relationships in a micronesian mangrove forest     

S. M. Gleason  K. C. Ewel  N. Hue 《Estuarine, Coastal and Shelf Science》2003,56(5-6):1065-1074

We examined characteristics of the soil environment related to redox in the rhizospheres of three mangrove species that commonly grow in similar hydrogeomorphic settings: Rhizophora apiculata BL, Bruguiera gymnorrhiza (L.) Lamk., and Sonneratia alba J. Redox potential (Eh) values and extractable P concentrations were significantly higher, whereas soluble reactive P (SRP) concentrations were significantly lower in Bruguiera plots than in either Rhizophora or Sonneratia plots. Correlations among Eh, SRP, pyrite and extractable P were significant only at plots with negative Eh values. Sonneratia and Bruguiera plots had significantly different soil redox conditions. Bruguiera plots were characterized by more oxidized soil conditions (ca. 80 mV), lower dissolved P concentrations in porewater (ca. 50%), and higher extractable P concentrations in soil (ca. 25%). Differences in Eh and P reflect real differences among species and appeared not to be associated with hydrology. Species-specific differences may be engendered by the trees themselves, or they may reflect microsite differences that have favored the germination, growth, and survival of particular mangrove species.  相似文献   

黄河水中镉（Ⅱ）与悬浮粒子液—固界面交换反应的研究   总被引：4，自引：1，他引：4  

杨宏伟  李琰 《海洋湖沼通报》1997,(3):25-32

本文研究了黄河悬浮粒子与镉（Ⅱ）相互作用的离子交换率（％）—pH曲线，以及河水中赖氨酸存在下对该曲线的影响。主要结果有；（1）镉以Cd（OH）+形式在悬浮粒子上进行阳离子交换，在天然pH下（8．0×8．5），镉离子交换率接近最大值；（2）镉离子浓度由8．9×10－6mol·L－1增加到2×8．9×10－6mol．L－1时，离子交换率降低；（3）浓度为6．8×10－6mol·L－1的赖氨酸对提高离子交换率起促进作用；（4）交换剂为转化沙的镉离子交换率比未转化沙小；（5）海水、金沙江水中悬浮粒子对镉的吸附弱于黄河水。  相似文献   

海水中萘的光化学降解研究   总被引：5，自引：1，他引：5       下载免费PDF全文

杨桂朋  戚佳琳 《海洋与湖沼》2003,34(1):56-66

系统研究了在高压汞灯或天然日光照射下萘在天然海水、人工海水和蒸馏水中的光降解情况。萘的光降解过程受到包括光源、溶液介质、溶解氧、重金属离子、光敏剂在内的各种因素的影响。实验证明，高压汞灯较天然日光更能有效地激发萘的光反应。开始的90min之内，萘的浓度慢慢下降，在照射90－120min后，萘的浓度迅速下降，这是整个萘光解过程中最有效的部分，一级反应速率常数为0.0075-0.0203min^-1。萘在天然海水中的光解速率大于在人工海水和蒸馏水中的光解速率，其主要原因是天然海水中存在天然光敏剂。同蒸馏水中的光反应相比，人工海水中的离子有助于提高萘的光解反应。然而，溶液中加入的重金属离子或光敏剂会改变萘的光解反应。此外，研究证明，溶解氧是必不可少的，它的存在大大加速了光反应。  相似文献   

离子交换水处理工艺与双室逆流再生离子交换床     

杨传蜀  程方 《海洋技术学报》2002,21(4):81-83

例举了离子交换水处理工艺，讨论了逆流再生离子交换器的结构设计特点，并给出主要具体设备参数。  相似文献   

利用AutoPrep离子色谱技术实现复杂基体样品中重稀土元素的分离和制备     

刘肖 王碗蔡亚岐  牟世芬 《岩矿测试》2007,26(3):176-182

研究了AutoPrep自动前处理装置和离子色谱联用技术分析复杂基体样品中重稀土元素的分离和半制备的方法。选用两个双层四通阀和一个六通阀替代传统方法中的四个双层四通阀，选用一个GS50四元梯度泵实现对螯合浓缩柱不同条件的淋洗，将吸附或交换在螯合柱和浓缩柱上的碱金属、碱土金属、过渡金属、重金属和重稀土元素选择性地分段洗脱，并将基体消除后的样品在线进样到CS5A离子色谱交换柱中进行最终分离，过柱衍生后进入紫外一可见光检测器进行光度检测，并根据确定的保留时间段进行在线样品收集，完成制备工作。对基体简单且被测组分含量较高的样品，采用直接进样法测定4种重稀土元素（Tb、Y、T和Lu）的检测限（S／N=3）为8．3-21．0μg，线性相关系数均大于0.9992，分离度均大于4，以峰面积计算的方法精密度（RSD，n=9）小于3％，回收率为89.0％～110.8％；对复杂基体样品或被测组分含量较低的样品，采用基体消除在线浓缩处理，方法的检测限（S／N=3）为0．67～1．43Ⅲ／L，线性相关系数均大于0，9994，分离度均大于3，方法的精密度（RSD，n=9）小于3％，回收率为91．2％～106．0％。对简单基体和复杂基体两种样品的分离和制备方法均具备灵敏度高、选择性好、自动化程度高、节省时间等特点．用于岩石等实际样品的检测．结果满意。  相似文献   

Geochemical characteristics of sediment pore water from Site XS-01 in the Xisha trough of South China Sea and their significance for gas hydrate occurrence     

Yang Tao  Jiang Shaoyong  Ge Lu  Yang Jinghong  Ling Hongfei  Wu Nengyou  Zhang Guangxue  Liu Jian  Chen Daohua 《Frontiers of Earth Science》2007,1(2):212-217

Gas hydrate is a recently-found new source of energy that mostly exists in marine sediments. In recent years, we have conducted gas hydrate exploration in the South China Sea. The Xisha trough, one of the promising target areas for gas hydrate, is located in the northern margin of the South China Sea, adjacent to several large oil and gas fields. The Xisha trough extends 420 km long with the water depth of 1 500 m in the west part and 3 400 m in the east part and deposits thick sediments with organic matter content of 0.41%–1.02%. Previous studies on topographical features, geological P-T conditions, structural geology, sedimentary geology and geophysical bottom simulating reflectors (BSR) in the Xisha trough suggest that this area is favorable for the formation and accumulation of gas hydrate. In this paper, we present geochemical analyses for the sediment and pore water from a piston core at Site XS-01 in the Xisha trough. Seven pore water samples were analyzed for their anion (Cl⁻, SO₄ ²⁻, Br⁻, I⁻) contents, cation (Na, K, Ca, Mg) contents and trace element (Li, B, Sr, Ba, Rb, Mn) contents. Eight sediment samples were analyzed for stable carbon and oxygen isotopic compositions. A number of geochemical anomalies such as anions (e.g. Cl⁻, SO₄ ²⁻), cations (e.g. Ca, Mg) and trace elements (e.g. Sr, Ba, B) were found in this study. For example, the concentrations of Cl⁻ and SO₄ ²⁻ in pore water show a decreasing trend with depth. The estimated sulfate/methane interface (SMI) is only 18 m, which is quite similar to the SMI value of 23 m in the ODP164 Leg 997 at Blake Ridge. The Ca, Mg and Sr concentrations of pore water also decrease with depth, but concentrations of Ba, and Mg/Ca and Sr/Ca ratios increase with depth. These geochemical anomalies are quite similar to those found in gas hydrate locations in the world such as the Blake Ridge and may be related to the formation and dissociation of gas hydrates. The salt exclusion effect during the gas hydrate formation will cause an increase in major ion concentrations in the pore waters that diffused upward such as Cl. The anaerobic methane oxidation (AMO) may lead to the change of SO₄ ²⁻ and other cations such as Ca, Mg, Sr and Ba in pore water. Low δ ¹³C value of authigenic carbonates is a good indicator for gas hydrate occurrence. However, the bulk sediment samples we analyzed all show normal δ ¹³C values similar to biogenic marine carbonates, and this may also suggest that no gas hydrate-related authigenic carbonates exist or their amount is so small that they are not detectable by using this bulk analytical method. In conclusion, we suggest that the Site XS-01 in the Xisha trough of the northern margin of the South China Sea is a potential target for further gas hydrate exploration. Translated from Quaternary Sciences, 2006, 26(3): 442–448 [译自: 第四纪研究]  相似文献   

塔里木盆地深层烃源岩可溶有机组分的碳同位素组成特征   总被引：3，自引：1，他引：3  

张中宁  刘文汇  郑建京  王琪  陈国俊  杨辉 《沉积学报》2006,24(5):769-773

塔里木盆地深层烃源岩主要是指埋深大于4000 m的寒武—奥陶系海相碳酸盐岩和三叠—侏罗系陆相泥岩、碳质泥岩和煤。研究表明,塔里木盆地深层烃源岩可溶有机组分的碳同位素组成具有母质继承效应,寒武—奥陶系海相腐泥型烃源岩可溶有机组分的碳同位素组成一般小于-28‰,而三叠—侏罗系陆相腐殖型烃源岩可溶有机组分的碳同位素组成一般大于-28‰。对于高演化的寒武—奥陶系海相深层烃源岩而言,在热力作用下,其可溶有机组分的碳同位素组成普遍发生强烈逆转,并出现饱和烃>芳烃>非烃>沥青质的完全反序分布现象,显示出深层环境下高演化烃源岩可溶有机组分的碳同位素组成特征。   相似文献   

Routine analysis of sediment pore water of high ionic strength     

Peter Herzsprung  Elke Bozau  Olaf Büttner  Anja Duffek  Kurt Friese  Matthias Koschorreck  Martin Schultze  Wolf v. Tümpling  Katrin Wendt‐Potthoff 《洁净——土壤、空气、水》2006,34(6):593-607

Pore water of sediments plays an important role in aquatic systems as mediator and as the reactive zone between the sediment and surface water. Sediment pore waters with high ionic strength from acidified pit lakes were investigated to obtain information about the influence on the lake water quality. The analysis of soluble reactive phosphorus, nitrate, ammonium, silica, dissolved organic carbon, ferrous iron, sulfate, chloride, sodium, potassium, calcium, magnesium, manganese, and total dissolved iron was predetermined as the dataset required for evaluation of water quality. The data collection procedure was optimised by designing a methodology for stabilisation, dilution of pore water samples and adaptation of analytical methods. The developed methodology was evaluated with respect to the effort required in the laboratory under routine conditions. In the first round of analyses, 72% of 638 individual analyses from a random selection of pore water profiles were found to be within the calibration ranges. Remedial actions to handle the remaining 28% of invalid analytical results are exemplified. Differences between comparative analyses of some ions by continuous flow analysis, ion chromatography, and atomic emission spectroscopy were evaluated. The majority of results measured by ion chromatography differed on a highly significant level from results measured by atomic emission spectroscopy. Possible reasons, originating from the extreme sample matrix, are discussed. Finally, the designed methodology and the results of the method comparison are used to recommend the selection of analytical methods under specific conditions.  相似文献   

溶液结构研究发展策略浅议   总被引：1，自引：1，他引：1       下载免费PDF全文

房春晖  房艳 《盐湖研究》2006,14(3):52-57

溶液结构被定义为研究溶液中溶剂化物种的微观结构及其与宏观性质之间关系的科学。简单叙述了其研究对象和研究方法,详尽阐述了其科学意义,介绍了其研究现状以及主要进展,并讨论了其研究策略。  相似文献   

Calibrations for benthic foraminiferal Mg/Ca paleothermometry and the carbonate ion hypothesis     

H. Elderfield  J. Yu  P. Anand  T. Kiefer  B. Nyland   《Earth and Planetary Science Letters》2006,250(3-4):633-649

Benthic foraminiferal magnesium/calcium ratios were determined on one hundred and forty core-top samples from the Atlantic Ocean, the Norwegian Sea, the Indian Ocean, the Arabian Sea and the Pacific Ocean, mostly at sites with bottom water temperatures below 5 °C. Mg/Ca ratios are consistently lower, by  0.2 mmol/mol, in samples cleaned using oxidative and reductive steps than using oxidative cleaning. Differences between Cibicidoides species have been identified: Mg/Ca of Cibicidoides robertsonianus > Cibicidoides kullenbergi > Cibicidoides wuellerstorfi. Comparison with bottom water temperatures support observations of lowered Mg/Ca of C. wuellerstorfi at temperature below  3 °C compared with values predicted by published calibrations and from other Cibicidoides species. Hydrographic data shows that carbonate ion saturation (Δ[CO₃²⁻]) decreases rapidly below this temperature. An empirical sensitivity of Δ[CO₃²⁻] on Mg/Ca has been established for C. wuellerstorfi of 0.0086 ± 0.0006 mmol/mol/μmol/kg. A novel application using modern temperatures and Last Glacial Maximum temperatures derived via pore fluid modelling supports a carbonate ion saturation state effect on Mg incorporation. This may significantly affect calculated δ¹⁸O_seawater obtained from foraminiferal δ¹⁸O and Mg/Ca temperature.  相似文献