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991.
992.
Zhanfei Liu Rachel L. Sleighter Junyan Zhong Patrick G. Hatcher 《Estuarine, Coastal and Shelf Science》2011
How dissolved organic matter (DOM) undergoes chemical changes during its transit from river to ocean remains a challenge due to its complex structure. In this study, DOM along a river transect from black waters to marine waters is characterized using an offline combination of reversed-phase high performance liquid chromatography (RP-HPLC) coupled to electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS), as well as tandem ESI-FTICR-MS. In addition, a water extract from degraded wood that mainly consists of lignins is used for comparison to the DOM from this transect. The HPLC chromatograms of all DOM samples and the wood extract show two major well-separated components; one is hydrophilic and the other is hydrophobic, based on their elution order from the C18 column. From the FTICR-MS analysis of the HPLC fractions, the hydrophilic components mainly contain low molecular weight compounds (less than 400 Da), while the hydrophobic fractions contain the vast majority of compounds of the bulk C18 extracted DOM. The wood extract and the DOM samples from the transect of black waters to coastal marine waters show strikingly similar HPLC chromatograms, and the FTICR-MS analysis further indicates that a large fraction of molecular formulas from these samples are the same, existing as lignin-like compounds. Tandem mass spectrometry experiments show that several representative molecules from the lignin-like compounds have similar functional group losses and fragmentation patterns, consistent with modified lignin structural entities in the wood extract and these DOM samples. Taken together, these data suggest that lignin-derived compounds may survive the transit from the river to the coastal ocean and can accumulate there because of their refractory nature. 相似文献
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<正> 一、概 况 在山东省泰安县潘河桥头Ⅳ号工区,解决岩溶地区坍陷问题中,试验研究采用大比例尺高精度重力测量,取得一定效果。 工区内灰岩埋深一般在25米左右,其上为第四系复盖,地形平坦,第四系的密度为1.9~2.0克/厘米~3,灰岩的密度为2.5~2.7克/厘米~3,上部为鲡状灰岩,溶蚀现象十分明显,岩溶发育,溶洞直径小的有几厘米,大的有几米,但最大直径没有超过10米。鲡状灰岩下部为豹皮灰岩,结构致密,也有小的溶洞存在。溶洞中多数充填砂粒、粘土等第四系沉积物。 相似文献
996.
Shao Mingshen Xu Dong Wang Yuchao Wang Ziyi Liang Xingzhou Li Li 《Natural Hazards》2022,112(2):1547-1566
Natural Hazards - The assessment of weathering degree of sandstone carvings plays an important role in scientific conservation. However, the current state of weathering assessment research cannot... 相似文献
997.
刘庆成 《华东地质学院学报》1995,18(1):43-47
本文介绍的油气勘查中的放射性测量,是一种油气普查新方法。它是利用油田上出现的负异常(或叫偏低场),反映了油气田的大体轮廓的基本原理进行的。前人及作者都取得了一定的工作成果。虽然取得了初步效果,但对机理等问题仍需进一步研究和完善。 相似文献
998.
蚀变岩中物质迁移的定量计算:以锡矿山锑矿床为例 总被引:6,自引:2,他引:6
本文提出了确定沉积岩蚀变作用过程中的不活动组分的方法,并以锡矿山锑矿床为例,定量计算了蚀变岩中各组分的带入带出量,研究表明:锡矿山锑矿硅化过程中TiO2和Al2O3为不活动组;SiO2,K2O,Na2O及锑,硫,坤,汞,铅和钡为带入组分;而CaO,MgO,Fe2O3,MnO及铜,锌为带出组分,锑,钡,硫,SiO2和CaO有较大的带进或带出量,锡矿山锑矿床矿石矿物为单一辉锑矿可能是由于矿液中缺少其它 相似文献
999.
1000.
Y. Hou X. Liu X. Zhang X. Chen K. Tao 《International Journal of Environmental Science and Technology》2016,13(3):887-896
The key components of S. triqueter root exudates involved 4-oxo-pentanoic acid, succinic acid, glutaric acid, phthalate acid, citric acid, vanillic acid, myristic acid, pentadecanoic acid, decanoic acid, 14-methyl-pentadecanoic acid, hexadecanoic acid, octadecanoic acid and oleic acid, and the content of the water-soluble organic acids (citric acid, succinic acid and glutaric acid) significantly increased in pyrene and lead co-contaminated rhizosphere soil. These three water-soluble organic acids including citric acid, succinic acid and glutaric acid were detected as the specific root exudates of S. triqueter under stress of pollutants for pyrene and lead, so they were chosen as the research objects, and they were added into the bioremediation systems of pyrene and lead co-contaminated wetland soils. Compared with the control, the treatments added the three organic acids always improved the quantity of the bioavailable fraction of pyrene and lead in wetland soils and greatly influenced other chemical states of pyrene and lead fractions in the test concentration range. Under the 50 g kg?1 of organic acids concentration, the amount of the bioavailable fraction of pyrene and lead increased 41.0 and 872.7 % by citric acid, respectively. The enhancement of bioavailability of pyrene and lead in the wetland soil by adding organic acids generally decreased in the following order: citric acid > succinic acid > glutaric acid. Enhancing effects of organic acids on the bioavailability improvement of pyrene and lead is remarkable. 相似文献