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

A model for the photochemistry of the global troposphere constrained by observed concentrations of H2O, O3, CO, CH4, NO, NO2, and HNO3 is presented. Data for NO and NO2 are insufficient to define the global distribution of these gases but are nonetheless useful in limiting several of the more uncertain parameters of the model. Concentrations of OH, HO2, H2O2, NO, NO2, NO3, N2O5, HNO2, HO2NO2, CH3O2, CH3OOH, CH2O, and CH3CCl3 are calculated as functions of altitude, latitude, and season. Results imply that the source for nitrogen oxides in the remote troposphere is geographically dispersed and surprisingly small, less than 107 tons N yr−1. Global sources for CO and CH4 are 1.5 × 109 tons C yr−1 and 4.5 × 108 tons C yr−1, respectively. Carbon monoxide is derived from combustion of fossil fuel (15%) and oxidation of atmospheric CH4 (25%), with the balance from burning of vegetation and oxidation of biospheric hydrocarbons. Production of CO in the northern hemisphere exceeds that in the southern hemisphere by about a factor of 2. Industrial and agricultural activities provide approximately half the global source of CO. Oxidation of CO and CH4 provides sources of tropospheric O3 similar in magnitude to loss by in situ photochemistry. Observations of CH3CCl3 could offer an important check of the tropospheric model and results shown here suggest that computed concentrations of OH should be reliable within a factor of 2. A more definitive test requires better definition of release rates for CH3CCl3 and improved measurements for its distribution in the atmosphere.

/pdf/tropospheric-chemistry-a-global-perspective-29u7u1il4s.pdf

Tropospheric chemistry: A global perspective

Atmospheric aerosols play important roles in climate and atmospheric chemistry: They scatter sunlight, provide condensation nuclei for cloud droplets, and participate in heterogeneous chemical reactions. Two important aerosol species, sulfate and organic particles, have large natural biogenic sources that depend in a highly complex fashion on environmental and ecological parameters and therefore are prone to influence by global change. Reactions in and on sea-salt aerosol particles may have a strong influence on oxidation processes in the marine boundary layer through the production of halogen radicals, and reactions on mineral aerosols may significantly affect the cycles of nitrogen, sulfur, and atmospheric oxidants.

https://science.sciencemag.org/content/sci/276/5315/1052.full.pdf

Atmospheric aerosols: Biogeochemical sources and role in atmospheric chemistry

Vegetation provides a major source of reactive carbon entering the atmosphere. These compounds play an important role in (1) shaping global tropospheric chemistry, (2) regional photochemical oxidant formation, (3) balancing the global carbon cycle, and (4) production of organic acids which contribute to acidic deposition in rural areas. Present estimates place the total annual global emission of these compounds between approximately 500 and 825 Tg yr−1. The volatile olefinic compounds, such as isoprene and the monoterpenes, are thought to constitute the bulk of these emissions. However, it is becoming increasingly clear that a variety of partially oxidized hydrocarbons, principally alcohols, are also emitted. The available information concerning the terrestrial vegetation as sources of volatile organic compounds is reviewed. The biochemical processes associated with these emissions of the compounds and the atmospheric chemistry of the emitted compounds are discussed.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/92GB02125%4010.1002/%28ISSN%291944-9224.NATSOUR1

Emissions of volatile organic compounds from vegetation and the implications for atmospheric chemistry

Atmospheric aerosol particles are known to contain organic carbon material in variable amounts, depending on their location. In some parts of the world, organic compounds make up the majority of the total suspended particle mass. This class of particulate matter is important in a wide range of geophysical and environmental problems, ranging from local issues (e.g., pollution toxicity) to the global scale (e.g., climate change). Unfortunately, the richness of organic chemistry and the highly variable physical properties associated with both natural and anthropogenic organic particles lead to great difficulties in sampling and obtaining complete chemical information on these materials. These obstacles result in an incomplete picture of a potentially significant part of atmospheric chemistry and a correspondingly poor understanding of the geophysical and environmental effects of this aerosol. Given the paucity of quantitative molecular data, the purpose of this paper is not to quantitatively describe the importance of organic aerosols in environmental issues, but rather to present a basis for defining what data are needed. With this goal in mind, we begin with an overview of the major environmental issues known to be affected by organic aerosols, followed by a description of the distribution, sources, and chemical and physical properties of organic aerosols as they are currently understood. Methods used to collect and study organic aerosols are provided, followed by a list of outstanding scientific questions and suggestions for future research priorities.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1998RG000045

Organic atmospheric aerosols: Review and state of the science

Extrapolating from extensive field measurements on foliar emissions in the U.S. approximate global inputs of isoprene and terpenes of 3.5 times 10 to the 14th power and 4.8 times 10 to the 14th power g(C)/yr, respectively, are obtained. The oxidation of these hydrocarbons could contribute in an important way to the atmospheric sources of CO (4.2-13.3 times 10 to the 14th power g/yr) and H2 (10-35 times 10 to the 12th power g/yr), and to organic species soluble in rainwater

Phillip L. Hanst

Papers

Estimates on the production of CO and H2 from the oxidation of hydrocarbon emissions from vegetation