This book is written as a reference on organic substances in natural waters and as a supplementary text for graduate students in water chemistry. The chapters address five topics: amount, origin, nature, geochemistry, and characterization of organic carbon. Of these topics, the main themes are the amount and nature of dissolved organic carbon in natural waters (mainly fresh water, although seawater is briefly discussed). It is hoped that the reader is familiar with organic chemistry, but it is not necessary. The first part of the book is a general overview of the amount and general nature of dissolved organic carbon. Over the past 10 years there has been an exponential increase in knowledge on organic substances in water, which is the result of money directed toward the research of organic compounds, of new methods of analysis (such as gas chromatography and mass spectrometry), and most importantly, the result of more people working in this field. Because of this exponential increase in knowledge, there is a need to pull together and summarize the data that has accumulated from many disciplines over the last decade.

Organic geochemistry of natural waters

Global warming and climate change concerns have triggered global efforts to reduce the concentration of atmospheric carbon dioxide (CO2). Carbon dioxide capture and storage (CCS) is considered a crucial strategy for meeting CO2 emission reduction targets. In this paper, various aspects of CCS are reviewed and discussed including the state of the art technologies for CO2 capture, separation, transport, storage, leakage, monitoring, and life cycle analysis. The selection of specific CO2 capture technology heavily depends on the type of CO2 generating plant and fuel used. Among those CO2 separation processes, absorption is the most mature and commonly adopted due to its higher efficiency and lower cost. Pipeline is considered to be the most viable solution for large volume of CO2 transport. Among those geological formations for CO2 storage, enhanced oil recovery is mature and has been practiced for many years but its economical viability for anthropogenic sources needs to be demonstrated. There are growing interests in CO2 storage in saline aquifers due to their enormous potential storage capacity and several projects are in the pipeline for demonstration of its viability. There are multiple hurdles to CCS deployment including the absence of a clear business case for CCS investment and the absence of robust economic incentives to support the additional high capital and operating costs of the whole CCS process.

https://www.elsevier.com/__data/assets/pdf_file/0005/96980/Current-status-carbon-capture.pdf

An overview of current status of carbon dioxide capture and storage technologies

Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

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Carbon capture and storage (CCS): the way forward

Gasoline- and diesel-powered vehicles are known to contribute appreciable amounts of inhalable fine particulate matter to the atmosphere in urban areas. Internal combustion engines burning gasoline and diesel fuel contribute more than 21% of the primary fine particulate organic carbon emitted to the Los Angeles atmosphere. In the present study, particulate (d[sub p] [le] 2 [mu]m) exhaust emissions from six noncatalyst automobiles, seven catalyst-equipped automobiles, and two heavy-duty diesel trucks are examined by gas chromatography/mass spectrometry. The purposes of this study are as follows: (a) to search for conservative marker compounds suitable for tracing the presence of vehicular particulate exhaust emissions in the urban atmosphere, (b) to compile quantitative source profiles, and (c) to study the contributions of fine organic particulate vehicular exhaust to the Los Angeles atmosphere. More than 100 organic compounds are quantified, including n-alkanes, n-alkanoic acids, benzoic acids, benzaldehydes, PAH, oxy-PAH, steranes, pentacyclic triterpanes, azanaphthalenes, and others. Although fossil fuel markers such as steranes and pentacyclic triterpanes can be emitted from other sources, it can be shown that their ambient concentrations measured in the Los Angeles atmosphere are attributable mainly to vehicular exhaust emissions. 102 refs., 9 figs., 6 tabs.

Sources of fine organic aerosol. 2. Noncatalyst and catalyst-equipped automobiles and heavy-duty diesel trucks

The Global Energy Assessment (GEA) brings together over 300 international researchers to provide an independent, scientifically based, integrated and policy-relevant analysis of current and emerging energy issues and options. It has been peer-reviewed anonymously by an additional 200 international experts. The GEA assesses the major global challenges for sustainable development and their linkages to energy; the technologies and resources available for providing energy services; future energy systems that address the major challenges; and the policies and other measures that are needed to realize transformational change toward sustainable energy futures. The GEA goes beyond existing studies on energy issues by presenting a comprehensive and integrated analysis of energy chalenges, opportunities and strategies, for developing, industrialized and emerging economies. This volume is a invaluable resource for energy specialists and technologists in all sectors (academia, industry and government) as well as policymakers, development economists and practitioners in international organizations and national governments.

Global Energy Assessment: Toward a Sustainable Future

: Geochemical reaction path modeling is useful for rapidly assessing the extent of water-aqueous-gas interactions both in natural systems and in industrial processes. Modeling of some systems, such as those at low temperature with relatively high hydrologic flow rates, or those perturbed by the subsurface injection of industrial waste such as CO2 or H2S, must account for the relatively slow kinetics of mineral-gas-water interactions. We have therefore compiled parameters conforming to a general Arrhenius-type rate equation, for over 70 minerals, including phases from all the major classes of silicates, most carbonates, and many other non-silicates. These data have been added to a computer code that simulates an infinitely well-stirred batch reactor, allowing computation of mass transfer as a function of time. Actual equilibration rates are expected to be much slower than those predicted by the selected computer code, primarily because actual geochemical processes commonly involve flow through porous or fractured media, wherein the development of concentration gradients in the aqueous phase near mineral surfaces, which results in decreased absolute chemical affinity and slower reaction rates. Further differences between observed and computed reaction rates may occur because of variables beyond the scope of most geochemical simulators, such as variation in grain size, aquifer heterogeneity, preferred fluid flow paths, primary and secondary mineral coatings, and secondary minerals that may lead to decreased porosity and clogged pore throats.

/pdf/a-compilation-of-rate-parameters-of-water-mineral-1o9qltikkk.pdf

A Compilation of Rate Parameters of Water-Mineral Interaction Kinetics for Application to Geochemical Modeling

Petroleum formation and occurrence. A new approach to oil and gas exploration

To investigate the potential for the geologic storage of CO2 in saline sedimentary aquifers, 1600 t of CO2 were injected at 1500 m depth into a 24-m-thick sandstone section of the Frio Formation, a regional brine and oil reservoir in the U.S. Gulf Coast. Fluid samples obtained from the injection and observation wells before CO2 injection showed a Na-CaCl‐type brine with 93,000 mg/L total dissolved solids (TDS) at near saturation with CH4 at reservoir conditions. Following CO2 breakthrough, samples showed sharp drops in pH (6.5‐5.7), pronounced increases in alkalinity (100‐3000 mg/L as HCO3) and Fe (30‐1100 mg/L), and significant shifts in the isotopic compositions of H2O, dissolved inorganic carbon (DIC), and CH4. Geochemical modeling indicates that brine pH would have dropped lower but for the buffering by dissolution of carbonate and iron oxyhydroxides. This rapid dissolution of carbonate and other minerals could ultimately create pathways in the rock seals or well cements for CO2 and brine leakage. Dissolution of minerals, especially iron oxyhydroxides, could mobilize toxic trace metals and, where residual oil or suitable organics are present, the injected CO2 could also mobilize toxic organic compounds. Environmental impacts could be major if large brine volumes with mobilized toxic metals and organics migrated into potable groundwater. The d 18 O values for brine and CO2 samples indicate that supercritical CO2 comprises ;50% of pore-fluid volume ;6 mo after the end of injection. Postinjection sampling, coupled with geochemical modeling, indicates that the brine gradually will return to its preinjection composition.

Gas-water-rock interactions in Frio Formation following CO2 injection: Implications for the storage of greenhouse gases in sedimentary basins

Concentrations of short-chain aliphatic acid anions (acetate, propionate, butyrate, and valerate) in 95 formation-water samples from 15 oil and gas fields in the San Joaquin Valley, California, and in the Houston and Corpus Christi areas, Texas, show three temperature regimes. The sandstone reservoir rocks range in age from Eocene through Miocene. The aliphatic acid anions of formation waters in zone 1 (subsurface temperatures lower than 80°C) are characterized by concentrations less than 60 mg/L and consist predominantly of propionate. The concentrations of aliphatic acid anions in zone 2 (temperatures 80 to 200°C) are much higher (up to 4,900 mg/L) than in zone 1, and decrease with increasing subsurface temperatures and age of their reservoir rocks; acetate forms more than 90% of the total anions. No aliphatic acid anions are believed present in zone 3, which is based on extrapolation of data in zone 2; the temperatures are higher than 200°C. Microbiologic degradation of acetate and dilution by mixing with meteoric water most probably explain the composition and concentration of aliphatic acid anions in zone 1. The trends in zone 2 and the absence of acid anions in zone 3 are explained by thermal decarboxylation of these acid anions as in the reaction: CH3COO- + H2O^rarrCH4 + HCO3-. Aliphatic acid anions generally contribute more than 50% and up to 100% of the measured alkalinity in the samples of zone 2. Their contribution to the alkalinity in zone 1 is small. Iodide concentrations generally increase with increasing concentrations of aliphatic acid anions, which supports the use of iodide as a good proximity indicator of petroleum. The aliphatic acid anions mainly result from the thermocatalytic degradation of kerogen. We believe that these anions, which are highly soluble, are produced and dissolved in the pore waters of the source rocks and are expelled to the reservoir rocks during dehydration of clays. Decarboxylation of these acid anions to the components of natural gas is believed to occur mainly in the reservoir rocks, thus resolving the difficult problem of explaining the primary migration of natural gas. Evidence for the formation of natural gas from decarboxylation of acid anions is provided by the ^dgrC13 values of total bicarbonate and CH4 and the good correlation between the proportions of these anions in formation waters (94% for acetate, 5% for propionate, and 2% for butyrate) and their decarboxylated gases in the natural gas produced (90% for methane, 5% for ethane, and 2% for propane). Calculations show that the amount of gas that can be generated from the decarboxylation of the reported acid anions is large and apparently adequate to produce the amounts of gas in these fields.

Aliphatic Acid Anions in Oil-Field Waters--Implications for Origin of Natural Gas

If CO2 released from fossil fuel during energy production is returned to the subsurface, will it be retained for periods of time significant enough to benefit the atmosphere? Can trapping be assured in saline formations where there is no history of hydrocarbon accumulation? The Frio experiment in Texas was undertaken to provide answers to these questions. One thousand six hundred metric tons of CO2 were injected into the Frio Formation, which underlies large areas of the United States Gulf Coast. Reservoir characterization and numerical modeling were used to design the experiment, as well as to interpret the results through history matching. Closely spaced measurements in space and time were collected to observe the evolution of immiscible and dissolved CO2 during and after injection. The high-permeability, steeply dipping sandstone allowed updip flow of supercritical CO2 as a result of the density contrast with formation brine and absence of a local structural trap. The front of the CO2 plume moved more quickly than had been modeled. By the end of the 10-day injection, however, the plume geometry in the plane of the observation and injection wells had thickened to a distribution similar to the modeled distribution. As expected, CO2 dissolved rapidly into brine, causing pH to fall and calcite and metals to be dissolved. Postinjection measurements, including time-lapse vertical seismic profiling transects along selected azimuths, cross-well seismic topography, and saturation logs, show that CO2 migration under gravity slowed greatly 2 months after injection, matching model predictions that significant CO2 is trapped as relative permeability decreases.

Yousif K. Kharaka

Papers

A Compilation of Rate Parameters of Water-Mineral Interaction Kinetics for Application to Geochemical Modeling

Petroleum formation and occurrence. A new approach to oil and gas exploration

Gas-water-rock interactions in Frio Formation following CO2 injection: Implications for the storage of greenhouse gases in sedimentary basins

Aliphatic Acid Anions in Oil-Field Waters--Implications for Origin of Natural Gas

Measuring permanence of CO2 storage in saline formations: the Frio experiment