Comparisons of pyrolysis parameters between source rocks and their clay-sized fractions: Implication for source material of hydrocarbon generation

In natural environments, organic-clay interactions are strong and cause organo-clay composites (a combination between organic matter [OM] and clay minerals) to be one of the predominant forms for OM occurrence, and their interactions greatly influence the hydrocarbon (HC) generation of OM within source rocks. However, despite occurring in nature, dominating the OM occurrence, and having unique HC generation ways, organo-clay composites have rarely been investigated as stand-alone petroleum precursors. To improve this understanding, we have compared the Rock-Eval pyrolysis parameters derived from more than 100 source rocks and their corresponding <2 μm clay-sized fractions (representing organo-clay composites). The results show that all of the Rock-Eval pyrolysis parameters in bulk rocks are closely positively correlated with those in their clay-sized fractions, but in clay-sized fractions the quality of OM for HC generation is poorer, in that the pyrolysable organic carbon levels and hydrogen index values are lower, whereas the residual organic carbon levels are higher than those in bulk rocks. Being integrated with the effects of organic-clay interactions on OM occurrence and HC generation, our results suggest that organo-clay composites are stand-alone petroleum precursors for HC generation occurring in source rocks, even if the source rocks exist in great varieties in their attributes. Our source material for HC generation comprehensively integrates the original OM occurrence and HC generation behavior in natural environments, which differs from kerogen and is much closer to the actual source material of HC generation in source rocks, and it calls for further focus on organic-mineral interactions in studies of petroleum systems.

Changes in selected physico-chemical properties of floodplain soils in three different land-use types after flooding

This article provides information on selected physico-chemical properties, including soil colour, texture, electrical conductivity, pH_H2O, pH_CaCl2, content of total carbon and Q_4/6 quotient, of the topsoil and subsoil of former flood sediments at three diverse vegetation plots in a floodplain and in two reference plots unaffected by floods, and changes of some soil properties caused by a new subsequent flood. Aggradation of flood sediments in the area was controlled both by local terrain morphology and vegetation type cover. Differences in the properties of sediments in the individual plot types were caused by the different production of litter, root biomass and carbon cycling before the new flood. Vertical distributions and inventories of ¹³⁷Cs in soils revealed the position and proportion of modern sediments in soil profiles, man-made filling of former erosion grooves and ploughing depths. The new flood of a lower hydrological power aggraded a thin layer of organo-clay sediment on the soil surface but showed minor effects on the investigated soil properties. The lowest dry bulk density and highest total porosity values were found in the topsoil of woody and grassy plots after the flood implying no substantial break down of soil aggregates by the flood. The highest dry bulk density values in the subsoil of fields indicated soil compaction from agricultural machinery. No increased soil salinity was found after the flood. The flood did not significantly affect the pH_H2O of the topsoil and subsoil; however, a significant increase in pH_CaCl2 was found for the topsoil of grassy plots and for all topsoil samples from the park. No significant increases in total carbon (C_tot) contents were found in topsoils of any plot types after the flood in spite of an accumulation of thin organo-clay material on the soil surface after the flood. However, significant increases in C_tot in subsoils of all plot types indicate the vertical migration of colloidal and dissolved organic carbon in soils during the flood. C_tot contents positively correlated with electrical conductivity values and negative correlated with pH values. The relatively minor changes in soil physico-chemical properties found after the flood can be explained by the short duration and small dynamic power of the flood, and the timing of sampling when the flood had receded and soil aeration was already being restored.

Investigations on thermo-mechanical properties of organically modified polymer clay nanocomposites for packaging application

Eco-friendly packing polymer materials are in the spotlight but, lack of new biodegradable polymers either natural or synthetic is yet to establish the market more competitively. So, in the present work, clay as a nano-filler is embedded and organically modified in some synthetic and natural polymers which are well established commercially to enhance their biodegradability. The impact of clay on the properties of synthetic polymers namely, poly(methyl methacrylate) (PMMA), poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVAc) and natural polymer cellulose acetate butyrate (CAB) was studied. Results from differential scanning calorimetric (DSC) showed a decrease in the glass transition temperature of organically modified polymer clay nanocomposites (PCC) than pure polymers. Scanning electron microscopy (SEM) displayed a uniform surface with small-sized crystallites distributed on the polymer surface. X-ray diffraction (XRD) spectra revealed the formation of enhanced intercalated structures in PCC. Furthermore, FTIR studies showed that the interlayer bonding (Si–O bands) of pure clay is deformed in PCCs. The tensile strength of PCC increased with an increase in organo-clay loading. This unique mechanical behavior is due to the agglomeration of organo-clay particles. Finally, the biodegradation studies revealed enhanced hydrolytic degradation in PCC than pure polymers. Hence, these PCCs are environmentally friendlier than their pure synthetic polymers without significant compromise in their properties, which makes it suitable for packaging industries.

A novel approach to quantifying resuspension resistance of sediment organic matter against coastal flow

&lt;p&gt;In order to estimate sediment organic carbon budget in coastal oceans and continental shelves, a first step is to estimate how much of the deposited organic matter is retained within a sediment matrix, for further remineralization and preservation on a geological timescale, rather being physically flushed away by benthic flow&lt;sup&gt;1&lt;/sup&gt;. This question becomes more challenging for the regions where &amp;#8216;mobile&amp;#8217; layers (e.g. fluff layer, fluid mud and nepheloid layer) are formed due to the massive organic matter inputs, and often frequent resuspension and deposition&lt;sup&gt;2&lt;/sup&gt;. Organic matter remineralization and preservation in sediments has been mostly investigated but often overlooks the role of flow-induced shear stresses on suspending the organic matter. While such flow influences in sediment organic matter budget may have little influence on sediment organic matter budget in deep oceans, it cannot be neglected in shallow-water coastal seas and continental shelves where cyclic resuspension, deposition and frequent storm events occur&lt;sup&gt;3,4&lt;/sup&gt;. To our knowledge, the resistance strengths of organic matter in sediments against flow resuspension has received little attention.&lt;/p&gt;&lt;p&gt;To investigate this knowledge gap, various organo-clay aggregates and organo-clay-sand aggregates formed under different flow conditions were investigated by a series of laboratory flume&lt;sup&gt;5&lt;/sup&gt; and high resolution X-ray Microcomputed Tomography (micro-CT) experiments&lt;sup&gt;6&lt;/sup&gt;. Herein, a novel methodology is proposed, which successfully establishes quantitative relationships between the resuspension resistance strengths of these organic aggregates and a wide range of flow intensities, from moderate to storm conditions. The results provide a basis for computing resuspension under a range of flow conditions and, hence improving estimates of the organic matter budget in the coastal zone. &amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;ol&gt;&lt;li&gt;Burdige, D. J. Preservation of organic matter in marine sediments: Controls, mechanisms, and an imbalance in sediment organic carbon budgets? Chem. Rev. &lt;strong&gt;107&lt;/strong&gt;, 467&amp;#8211;485 (2007).&lt;/li&gt; &lt;li&gt;McKee, B. A., Aller, R. C., Allison, M. A., Bianchi, T. S. &amp; Kineke, G. C. Transport and transformation of dissolved and particulate materials on continental margins influenced by major rivers: Benthic boundary layer and seabed processes. Cont. Shelf Res. (2004). doi:10.1016/j.csr.2004.02.009&lt;/li&gt; &lt;li&gt;Burdige, D. J. Burial of terrestrial organic matter in marine sediments: A re-assessment. Global Biogeochem. Cycles &lt;strong&gt;19&lt;/strong&gt;, 1&amp;#8211;7 (2005).&lt;/li&gt; &lt;li&gt;Nicholls, R. J. &amp; Cazenave, A. Sea-level rise and its impact on coastal zones. Science (2010). doi:10.1126/science.1185782&lt;/li&gt; &lt;li&gt;Thompson, C. E. L., Couceiro, F., Fones, G. R. &amp; Amos, C. L. Shipboard measurements of sediment stability using a small annular flume-core mini flume (cmf). Limnol. Oceanogr. Methods (2013). doi:10.4319/lom.2013.11.604&lt;/li&gt; &lt;li&gt;Zhang, N. et al. Nondestructive 3D Imaging and Quantification of Hydrated Biofilm-Sediment Aggregates Using X-ray Microcomputed Tomography. Environ. Sci. Technol. &lt;strong&gt;52&lt;/strong&gt;, 13306&amp;#8211;13313 (2018).&lt;/li&gt; &lt;/ol&gt;

The effect of hydrogenation of epoxy resin on the dispersion of organo-clay in the epoxy resin matrix

The hydrogenated diglycidylether of Bisphenol A epoxy resin (HDGEBA)was successfully employed to prepare nanocomposites with a more homogeneous distribution of clay, compared to that of bisphenol A epoxy resin (DGEBA)/clay system. Nanocomposites, with amounts up to 7.5 wt% of Organo-clay, were synthetized by means of “slurry-compounding” method and followed by a curing process with cis-1,2-Cyclohexanedicarboxylic anhydride and Glutaric Anhydride as the curing agent. A combination of X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the dispersion behavior of organo-clay in epoxy/clay nanocomposites. It was found that, in HDGEBA/clay nanocomposites, organo-clay was uniformly dispersed and even partly exfoliated, whereas, in DGEBA/clay system, large particle aggregates were seen when examined by TEM under lower magnification. Accordingly, the rheology and compatibility experiments were carried out to investigate the interactions within each system. It turned out that, after hydrogenation, HDGEBA was endowed with stronger interactions with organo-clay, thus resulting in the enhanced dispersion behavior, which may generate more chances to be mechanically reinforced by adding inorganic clays.