Limitations of the Quantification of Organic Carbon in Sediment from C–H Stretching Vibrations in DRIFT Spectra

Abstract

The limitations of quantifying organic carbon (OC) or various organic substances in sediment from the integration of infrared C–H stretching bands using diffuse reflectance infrared Fourier transform (DRIFT) spectra are pointed out, both from theoretical arguments and by presenting experimental data. Such determinations are inaccurate and imprecise because (i) the band at 2930 cm^?1 is not exclusively due to CH₂ groups; (ii) there is a spectral interference from CO₃ ^2? absorption; and (iii) the proportion of CH₂ groups in organic matter varies for different sediments. The measurement of aliphatic C–H stretching band areas only provides an approximate measurement of aliphatic carbon bonded to hydrogen, which turns out to be a factor of about 3 to 3.5 times smaller than the OC content for Hong Kong marine sediments, depending on their nature and origin.     

Isotopengeochemische Charakterisierung kohlenwasserstoffbildender organischer Substanzen

Within the framework of a larger research project on contributions of isotope investigations to natural gas and crude oil exploration, the following publication is a first part of research reports from the author's laboratory.

The isotopic composition of carbon in fossil organic matter is primarily determined by the type of biological precursors. The main constituents forming organic matter in sediments are higher plants and microorganisms (algae, bacteria). These precursors contain a great number of organic compounds with corresponding isotope signatures. Hydrocarbons and lignin e.g., are enriched in carbon 13, while lipids in most cases are depleted.

Semi-empirical calculations on a thermodynamic basis are used to precalculate isotopic compositions of components or single compounds, applying the so-called β-factor method. The results are compared with numerous data from references about isotopic compositions of higher plants, algae and plant components. Also environmental conditions of plant growing-including paleoenvironment-have been taken into consideration.

The δ¹³C values of more than 150 types of organic substances in sediments of several geological formations have been measured in our isotope geochemical department.

The results allow a characterization and classification of organic matter: humic and sapropelitic organic substances can in many cases be distinguished by their isotopic signatures taking into account exceptions of e.g., regional origins. Influences of maturity (characterized by vitrinite reflectance) and especially of macerale composition of organic matter on it's isotope values and on the formation of hydrocarbons including their isotopic compositions are elucidated. The interpretation concept is also assured using special examples of drilling sites in Germany. The obtained results and proposed interpretation concept can contribute to further development in the understanding of hydrocarbon formation and natural gas exploration.     

Selection of optimal combinations of inputs in a partial least squares model for prediction of soil organic matter

Abstract

Partial least squares model is widely used in estimation of soil physical and chemical parameters such as soil organic matter and moisture content, due to its advantages in dealing with collinearity of variables like hyperspectral reflectance. However, it is hard to determine optimal combination of partial least squares model input for soil organic matter prediction since there are lots of possibilities such as, different mathematical transformation of spectral reflectance, wavelength ranges, and spectral resolution. Laboratory hyperspectral reflectance of soils in Songnen plain were analyzed in this study, and the orthogonal experimental design method for deriving optimal combination of input variables for soil organic matter prediction models was introduced. For intercalating orthogonal experimental design table, five different levels which commonly used by researchers were assigned to factors. Results show that the optimal combination input for single black soil is using the derivative logarithmic reciprocal reflectance in the wavelength range selected by multiple stepwise regression at a spectral resolution of 5?nm (R²=?0.95, RMSE?=?0.21, and RPD?=?4.49), and different soils is using continuum removed in the wavelength range selected by MSR at a spectral resolution of 5?nm (R²?=?0.77, RMSE?=?0.74, and RPD?=?2.08). With optimal combination input, the partial least squares model prediction ability was evaluated as excellent for single black soil, possible for different soils. This study illustrates the orthogonal experimental design method can be an effective way to identify the optimal input variables of a partial least squares model for soil organic matter prediction, and multiple stepwise regression can be a preprocessing step to reduce hyperspectral data redundancy before using partial least squares to predict soil organic matter. Overall, this study provides a new approach for determining optimal input of partial least squares predicting model.     

Environmental Applications of Excitation-Emission Spectrofluorimetry: An In-Depth Review II

Abstract: This part is devoted to the environmental applications of excitation-emission spectrofluorimetry (EES): Characterization of chromophoric dissolved organic matter (CDOM) in drinking waters, rivers, fog waters, lakes, oceans, leachates, wastewaters, sluge, bioreactor membrane foulants, and soils; characterization of extracellular polymeric substances in sludges; study of interactions between CDOM and organic pollutants in soils; and quantification of organic pollutants in waters and soils. This part includes the pretreatment of samples, and the environmental applications of the technique are discussed, including its application to bioremediation of wastewaters.

More than 200 references (focusing mainly on the last 10 years) from all kinds of journals (environment, analytical chemistry, biotechnology) have been carefully revised and included in this part of the article.     

Validation of computations by high pressure measurements: Solutions to problems that experiments cannot solve

Abstract

Calculations of the properties of condensed matter systems can be crucially tested by comparison with their experimental pressure behavior. When validated by such a comparison theoretical models become reliable computer experiments and can be used to explore properties of the system which are intrinsically unobservable by experiment alone.

Three examples are given of such methods:

(i) The behavior of wurtzite indium nitride under pressure which is shown to be due to a second-order isostructural phase transition.

(ii) The instability of tetrahedrally bonded semiconductors (Ge) under pressure which turns out to be related to a second-order process.

(iii) The explanation of the lattice dynamics of a-boron at ambient conditions which can be understood only by comparison of its high pressure behavior with calculations.     

Two-dimensional detector software: From real detector to idealised image or two-theta scan

Abstract

Detector systems introduce distortions into acquired data. To obtain accurate angle and intensity information, it is necessary to calibrate, and apply corrections. Intensity non-linearity, spatial distortion, and non-uniformity of intensity response, are the primary considerations.

It is better to account for the distortions within scientific analysis software, but often it is more practical to correct the distortions to produce ‘idealised’ data.

Calibration methods and software have been developed for single crystal diffraction experiments, using both approaches. For powder diffraction experiments the additional task of converting a two-dimensional image to a one-dimensional spectrum is used to allow Rietveld analysis. This task may be combined with distortion correction to produce intensity information and error estimates.

High-pressure experiments can introduce additional complications and place new demands on software. Flexibility is needed to be able to integrate different angular regions separately, and to produce profiles as a function of angle of azimuth. Methods to cope with awkward data are described, and examples of the techniques applied to data from high pressure experiments are presented.     

Forensic Studies by EA-IRMS

Abstract

The authenticity of natural and synthetic matter can be checked by measurement of the isotope ratios of C, N and S. Controlled substances like drugs of abuse (cocaine, heroin) and explosives (TNT) or, simply, traces of paint can hold information in their isotope pattern. Total combustion of samples in an elemental analyzer followed by on-line determination of the isotopes of the combustion products (CO², N², SO²) in an isotope ratio mass spectrometer (EA-IRMS) provides high sample throughout with a minimum of sample preparation.     

Canopy Gradients in δ18O of Organic Matter as Ecophysiological Tool

Abstract

We determined vertical oxygen isotope gradients of leaf organic matter for a grassland in Switzerland and a mountain beech forest (Fagus sylvatica) in Northern Italy. A distinctly positive ¹⁸O/¹⁶O gradient with height above ground was found for the grassland (7.9‰m^?1, p < 0.001), whereas the gradient was negative for the forest (–0.077‰m^?1, p < 0.001). The results are consistent with microclimatic measurements, although large isotope variations between the species have to be taken into account for the grassland. A conceptual scheme is shown which relates the isotope enrichment to the canopy density, considering the effects of transpiration and canopy structure. We conclude that the analysis of the within canopy variation in δ¹⁸O of organic matter can be used to provide long-term estimates of leaf water isotope composition, thus improving existing isotope methods to determine the gas-exchange between vegetation and atmosphere.     

Chemical and Isotope Investigations in Dissolved Gases of a Meromictic Residual Lake

Abstract

Lake Hufeisen near Halle/Saale has been formed in an old mining pit. Its deepest part is trench shaped and filled with water of sodium chloride content. Due to the density difference strong mixing processes in this part of the water body are prevented all over the year (meromictic lake). Therefore anoxic conditions have been established and the organic matter of the lake sediments is converted to carbon dioxide and methane. Over a period of more than one year gas samples were collected from different water depths. The investigations of the chemical composition (mainly nitrogen, carbon dioxide and methane) and the carbon isotope ratios show different relationships for individual species. The results are discussed with respect to the behaviour of the gases in the water column and to the stability of the density stratification in the saline bottom water.     

13C and 15N Abundances in the Sediment Core (VER 92/1-St-10-GC2) from Northern Lake Baikal

Abstract

Carbon and nitrogen stable isotope compositions of organic matter, TOC/TN ratio, and manganese concentration in a sediment core that was collected in northern part of Lake Baikal (VER92ST10-GC2, water depth at 922 m, about 3 m long) were investigated to elucidate the origin of the sedimentary organic matter and its associated environmental factors.

The sediment core was composed of mainly two parts: turbidite sections and other sections. Constant δ¹³C and δ¹⁵N values of the turbidite sections were observed (- 26.8 ±0.2 ‰ for δ¹³C and 3.2 ± 0.1 ‰ for δ¹⁵N) throughout the core. The higher δ¹³C in turbidite sections (about - 27 ‰) than that of the other sections (- 31 to - 29 ‰) was clearly observed, and δ¹⁵N was different between turbidite sections (about 3‰) and other sections (3 to 5 ‰). δ¹³C of other sections was close to that of pelagic phytoplankton, indicating that sediment other than turbidite sections is composed of autochthonous components. The variation of stable isotopes in other sections may be possibly caused by the changes in either phytoplankton growth rate or contribution ratios of terrestrial to aquatic plants for δ¹³C. Either denitrification or fluctuation of δ¹⁵N in pelagic phytoplankton can be the cause of variable δ¹⁵N in other sections.     

Inkorporation von 15N-markiertem Harnstoff in Organogene Dünge- und Abfallstoffe während der Rotte

Abstract

Eight organic fertilizers and wastes enriched with ¹⁵N labelled urea were stored at 25°C for one year. At the end of the experiment the ¹⁵N recovery rate ranged between 24 and 100%. The distributions of inorganic nitrogen (NH₄- and NO₃-N) and organic nitrogen (fulvic acids, humic acids and non extractable substances) are ascertained. Between the test materials, there are great differences in incorporation parameters.     

Stabile Isotope in den Interaktionen von Parasiten und Wirten bei Höheren Pflanzen

Abstract

An overview is given about the δ¹³C- and δ5D-values in the organic material of hemi- and full- parasitic higher plants and of their hosts.

Hemiparasites have to direct the content of the host xylem into their tissues by lowering their water potential. They achieve this by active water secretion or by lowering the stomatal resistance. In the latter case, the intercellular CO₂-concentration in the chlorenchyme of the parasite is increased. This causes a reduction of the ¹³C-content (δ¹³C-value of the parasite more negative than of the host). The dry matter of the mistletoes is always richer in deuterium than that of the host. The reason for this fact is unknown.

In the case hemiparasites and their hosts show differences in the ¹³CO₂-discrimination during the photosynthetic CO₂-fixation, an eventual transfer of organic material from host to parasite can be checked. By this way a holoparasitic mistletoe, Tristerix aphyllus, could be demonstrated.

In contrast to mistletoes on C3-hosts, such on CAM-hosts have a lower deuterium content in the dry mass than the hosts.

Holoparasites get all their organic material from the hosts and mirror, therefore, in their δ¹³C-values those of the hosts. Their deuterium content in the organic material is always higher than the one in the host. The reason is unknown.     

Beiträge zur Isotopengeochemie von Erdgasen

It is the proper aim of geochemical investigations regarding natural gas to describe the processes of generation, migration and accumulation of gaseous compounds. By this way our research results should contribute to knowledge about the gas generating potential of organic matter and about the expected gas volumes in natural gas deposits.

The main topics in the authors' research project are

- isotopic characterization of hydrocarbon forming organic matter

- simulation of the generation of natural gas components by coalification processes (model experiments including also radiolytic gas formation from organic matter)

- investigation of various separation processes (diffusion, adsorption, solubility, mixing of gases. oxidation of natural gas components) affecting chemical compositions and isotopic signatures

- elucidation of pressure and temperature dependence of separation processes and especially of the elementary isotope separation cofficients in systems gas/sorbent

- as the main result, an interpretation concept for natural gas samples is proposed which is based on chemical and isotopic compositions of methane and ethane in the samples and which takes into consideration also separation processes.

Following this summarizing publication some of the most important results of our research work will be presented in more detail in three separate parts.     

The Spectrofluorometric Monitoring of Water Purification by Natural Alternatives

Aim: Determination of efficiency of zeolite and hydrolytic enzymes isolated from earthworms in water purification.

Methods: The autofluorescence of water was investigated by fluorescence excitation–emission matrix. The purification of water was carried out with natural zeolite and hydrolytic enzymes isolated from earthworms. These methods were applied to samples that contain ciliates that were detected with atomic force spectroscopy.

Results: The zeolite removed ammonia and partly eliminated some organic compounds. The hydrolytic enzymes were efficient in biodegrading organic compounds present in water.

Conclusion: Zeolite and enzymes are applicable in water purification.     

Gas Forming Processes within Lignite Mining Dumps

Abstract

Gas analyses of the soil atmosphere of lignite mining dumps yielded increased contents of carbon dioxide. To get information about the potential sources and the carbon dioxide releasing capacity of the dumps, samples of dump material were investigated for their contents and isotopic compositions of organic and inorganic carbon as well as the carbon dioxide in the soil atmosphere. The contents of organic and inorganic carbon were found to vary depending on type of dump material. The isotopic composition of the organic carbon ranges between ?24.5 and ?26.5‰, which is typical for humous materials. The carbonates are found to be of marine origin (δ¹³C: +0.5 to ?1.1‰). By means of the isotope investigations it could be shown that the carbon dioxide in the lignite mining dump arises from these two different sources. Mixing ratios can be calculated using the isotope balance equation. Both reaction paths are associated with oxygen consumption and do not result in an increased gas pressure within the dump.     

Estimating Spatial and Seasonal Phytoplankton δ13C Variations in an Estuarine Mangrove Ecosystem

Abstract

In estuarine ecosystems, large spatial and seasonal variations in δ¹³C values of primary producers can occur, and knowledge of these variations may be crucial when interpreting stable isotope data of higher trophic levels. Obtaining clean phytoplankton samples for isotope analysis is usually impossible in such systems, and analysis of total suspended matter is not a simple proxy for phytoplankton δ¹³C variations. Based on a few simple assumptions regarding the C and N content of the two end-members (terrestrial detritus and phytoplankton) and the δ¹³C of the terrestrial component, we here present a simple model to estimate the phytoplankton δ¹³C variations using an existing dataset on the δ¹³C and elemental (C:N) composition of suspended organic matter from an estuarine mangrove ecosystem in southeast India.

These variations are related to the monthly rainfall pattern during the sampling period. It is stressed that this method estimates approximate phytoplankton δ¹³C values, which should not be used in e.g., mixing models. However, we propose that in cases where sufficiently large datasets are available, the described procedure could provide a valuable method to semi-quantitatively estimate the seasonal or spatial variations of the phytoplankton δ¹³C signal.     

Anomalously high heat capacity of liquids: relation to structural properties

ABSTRACT

Heat capacity of several liquids which demonstrate anomalous behaviour is studied. It is shown that isochoric heat capacity of these liquids shows anomalously high values which is related to smooth structural crossover in these liquids. This phenomenon can be used for qualitative explanation of high heat capacity of water and some other substances.     

Constructing amorphous RuxOy on CuO/Cu2O nanowire arrays for improved oxygen evolution

More than 50% of engineered nanomaterials released into the environment contain silver nanoparticles (Ag-NPs). The mobility, bioavailability, and toxicity of engineered Ag-NPs are known to depend on their properties and the environmental conditions. However, almost nothing is known about the fate of naturally occurring Ag-NPs, which are formed during the reduction of Ag⁺ by natural organic matter, primarily humic substances (HSs). The aim of this work was to study the interaction of soils and plants with simulated natural Ag-NPs, i.e., Ag-NPs stabilized with HSs (Ag-HS-NPs). To reach this goal, Ag-HS-NPs were synthesized, and their sorption-desorption behavior on two contrasting soils (a mineral soil and one rich in organic matter) was evaluated, including alterations in the mineral composition of the soil solution. In parallel, the influence of Ag-HS-NPs on wheat seedling growth was estimated. Introduction of Ag-HS-NPs into the soils resulted in a 1.3- to 2-fold or greater increase in the concentration of many elements in the soil solution (Al, Cr, Cu, Fe, etc.), and this effect was more pronounced for the organic soil than for the mineral soil. To explain this effect, we hypothesized that this phenomenon was due to the partial dissolution of Ag-HS-NPs leading to the production of Ag⁺ that could be further reduced by soil organic matter, which was correspondingly oxidized. Therefore, the partial breaking of soil aggregates because of the decomposition of soil organic matter in the presence of Ag-HS-NPs could be expected. Plants treated with Ag-HS-NPs demonstrated a lower rate of water uptake, which decreased by over 81%. The shoot and root biomass decreased by 15–17% and by 13–15%, respectively. This study clearly demonstrates an underestimated hazard of Ag-NPs formed in nature in terms of their ability to adversely affect the environment.

     

Research and development at rist

Abstract

The Research Institute for Solvothermal Technology (RIST) opened in September, 1997 to carry out research related to high-temperature and high-pressure fluid technology. The RIST is unique institute specialized high pressure science and technology in Japan, and probably in the world. According to government, the institute is defined as the core facility of a West-Japan creative economic development base zone.

Nowadays, RIST has developed new technologies using supercritical fluids, especially carbon dioxide and water, in areas related to the environment, such as the treatment of organic waste, the production of new materials, such as “new-carbon” substances, materials for batteries and electromagnetic wave absorption, and in the area of energy and resources, such as the conversion or the recycling of industrial plastic waste.

A review will be given on the research and development activities at RIST. It is focused on several essential results obtained in recent investigations. Progressive joint research projects with the cooperation of enterprises, universities and government will be described.     

New packaging solutions for high pressure treatments of food

Abstract

High pressure is a promising technology for developing new processes in food treatment. In most cases, pre-packaged foods are used in high pressure treatments (HP). Consequently, the behavior of the package under treatment conditions is an important factor. The following work was devoted to the evaluation of different packages under high pressure conditions in the presence of different substances used as simulants. Three main characterizations were carried out after HP treatment: mechanical resistance, barrier properties and integrity.

The experimental results using multilayer plastic films (PA/PE) have led to the selection of several solutions which may be used as packages for high pressure treatments.