Biogeochemistry An Overview

Our investigations of the biogeochemistry of DMS have focussed on a variety of coastal marine environments. In this paper we present an overview of our research on the processes leading to DMS production and consumption. We discuss our results in the context of obtaining a broader understanding of DMS cycling in the marine environment. 

A historical perspective of the primary research that has shaped our current understanding of Amazon shelf biogeochemistry is presented initially as an overview. The primary focus of the chapter, however, is on biogeochemical cycles and related insights that have been developed during the past 5 years, many of which have come from the recendy completed AmasSeds Project (see Nittrouer and DeMaster 1996, for overview). 

Ludwig J., Meixner F. X., Vogel B., and Fdrstner J. (2001) Soil-air exchange of nitric oxide an overview of processes, environmental factors, and modeling studies. Biogeochemistry 52, 225-257. 

Laturnus F., Haselmann K. F., Borch T., and Gron C. (2(X)2) Terrestrial natural sources of trichloromethane (chloroform, CHC13)—an overview. Biogeochemistry 60, 121—139. 

Anthropogenic inputs to intertidal environments are often direct, through point-source waste disposal, but they are also indirect, from riverine, marine and/or atmospheric sources. Trace metals are partitioned between each component of the intertidal sediment-water system they are found in solution ( bulk water or interstitial water) and associated with suspended and deposited sediments. This chapter is concerned with the biogeochemistry of trace metals in deposited intertidal sediments. Two main sections follow in the first, an overview of surface sediments and sediment depth profiles is presented, and in the second, a case study is given of the historic record of Zn from saltmarsh sediments in the Severn Estuary, UK. 

An Overview of the Biogeochemistry of Fossil Fuel Hydrocarbons in the Marine Environment... 

The book focuses on the biogeochemistry of trace elements in arid and semiarid zone soils and includes an introductory chapter on the nature and properties of arid zone soils. It presents an updated overview and a comprehensive coverage of the major aspects of trace elements and heavy metals that are of most concern in the world s arid and semi-arid soils. These include the content and distribution of trace elements in arid soils, their solution chemistry, their solid-phase chemistry, selective sequential dissolution techniques for trace elements in arid soils, the bioavailability of trace elements, and the pollution and remediation of contaminated arid soils. A comprehensive and focused case study on transfer fluxes of trace elements in Israeli arid and semi-arid soils is presented. The book concludes with a discussion of a quantitative global perspective on anthropogenic interferences in the natural trace elements distributions. The elements discussed in this book include Cd, Cu, Cr, Ni, Pb, Zn, Hg, As, Se, Co, B, Mo and others. This book is an excellent reference for students and professionals in the environmental, ecological, agricultural and geological sciences. 

A schematic overview of the relevant processes is shown in Figure 1. Plants and other autotrophs fix CO2. Animals and other heterotrophs utilize organic compounds. If the assimilated carbon is a small molecule (like CO2, CH4, or acetate), significant isotopic fractionation is likely to accompany the fixation or assimilation of C. Such fractionations establish the isotopic relationship between an organism and its carbon source. Those associated with photosynthesis encode information about chemical and physical conditions in the environment of fixation. Logically, therefore, they are treated here in the chapter dealing with the biogeochemistry of marine basins (Freeman, this volume). 

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