In situ Raman microspectroscopic analysis of soot samples with different organic carbon content: Structural changes during heating

The dry weight and organic carbon content of eggs and components of Clyde spring herring eggs were measured at intervals during their development. Comparison with previously published data suggests that an increase has occurred in the weight of these eggs over the past thirty years. It is clear that only a small proportion of the material deposited in the form of herring spawn actually remains attached to the substratum when the larvae hatch and so is available for potential integration into the benthic food web. This was confirmed by the determination at intervals over two years of the organic carbon content of the gravel sediments on spawning grounds of the Clyde spring herring. Although the deposition of herring spawn resulted in an immediate marked increase in the carbon content of the spawning ground sediments, carbon levels quickly returned to pre-spawning levels and there was no evidence of any permanent or long lasting increase. This held true when the spawn died and decayed in situ and even when it was mixed into the sediment by wave action. The rapid decrease in carbon levels is attributed to the strong water movements which frequently occur over the spawning grounds.

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Mobility of Polyethylene Glycol-Modified Urethane Acrylate (PMUA) Nanoparticles in Soils

E3S Web of Conferences ◽

10.1051/e3sconf/202014101002 ◽

2020 ◽

Vol 141 ◽

pp. 01002

Author(s):

Warapong Tungittiplakorn ◽

Viranart Kongbua ◽

Anyamanee Tulaphan ◽

Kannika Kaewtawee

Keyword(s):

Organic Carbon ◽

Carbon Content ◽

Clay Soil ◽

Urethane Acrylate ◽

Organic Carbon Content ◽

Batch Experiments ◽

Clay Loam Soil ◽

Soil Flushing ◽

Loam Soil

Engineered nanoparticles (ENPs) have been reported for their potential to enhance in situ soil remediation due to their size and stability in water. These properties allow them to pass through soils with minimal loss in soil flushing or pump-and-treat process. The success of nanoparticle-facilitated soil flushing depends on the mobility of nanoparticles in the soil matrix. However, organic carbon content and soil texture can affect the mobility of nanoparticles in soils. This study compared the mobility of polyethylene glycol-modified urethane acrylate (PMUA) nanoparticles in three types of soils with varying organic contents. The results of two consecutive injection experiments showed that the recovery of injected nanoparticles through a soil column were 91 and 97% for sandy soil with carbon content of 0.01%, 81 and 85% for clay loam soil with organic carbon content of 1.20% and 67 and 73% for clay soil with organic carbon content of 3.25%. Furthermore, the batch experiments showed that the distribution coefficient (Kd) of PMUA nanoparticles between water and sandy soil, clay loam soil, and clay soil were 1.86, 2.34 and 3.01 mL/g, respectively. This conforms to the column experiment results and confirms that the increase in organic carbon content in soils increases the adsorption of PMUA nanoparticles, and therefore decreases the mobility of the nanoparticles through soils. Moreover, the distribution coefficient from batch experiments could be used to predict the mobility of PMUA nanoparticles in soils, and the viability of in situ PMUA-facilitated soil flushing method for specific contaminated soils.

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The use of in situ volumetric water content at field capacity to improve the prediction of soil water retention properties

Canadian Journal of Soil Science ◽

10.4141/cjss07065 ◽

2008 ◽

Vol 88 (4) ◽

pp. 533-541 ◽

Cited By ~ 36

Author(s):

Hassan Al Majou ◽

Ary Bruand ◽

Odile Duval

Keyword(s):

Organic Carbon ◽

Carbon Content ◽

Water Content ◽

Bulk Density ◽

Water Retention ◽

Field Capacity ◽

Volumetric Water Content ◽

Organic Carbon Content ◽

Water Retention Properties

Most pedotransfer functions (PTF) developed over the past three decades to generate water retention characteristics use soil texture, bulk density and organic carbon content as predictors. Despite the high number of PTFs published, most being class- or continuous-PTFs, the accuracy of prediction remains limited. In this study, we compared the performance of different class- and continuous-PTFs developed with a regional database. Results showed that the use of in situ volumetric water content at field capacity as a predictor led to much better estimation of water retention properties compared with using predictors derived from the texture, or the organic carbon content and bulk density. This was true regardless of the complexity of the PTFs developed. Results also showed that the best prediction quality was achieved by using the in situ volumetric water content at field capacity after stratification by texture. Comparison of in situ volumetric water content at field capacity, with the water retained at different matric potentials as measured in the laboratory, showed field capacity to approximate 100 hPa, whatever the soil texture. Finally, the lack accuracy of PTFs that do not use the in situ volumetric water content at field capacity as predictor did not appear due to the test soils being unrepresentative of the soils used to develop the PTFs, but were instead related to poor correlations between the predictors used and the water retention properties. Key words: Pedotransfer functions, root mean square error, mean error of prediction, standard deviation of prediction, texture, bulk density, organic carbon content

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