In many marine environments, a voltage gradient exists across the water‐sediment interface resulting from sedimentary microbial activity. Here we show that a fuel cell consisting of an anode embedded in marine sediment and a cathode in overlying seawater can use this voltage gradient to generate electrical power in situ. Fuel cells of this design generated sustained power in a boat basin carved into a salt marsh near Tuckerton, New Jersey, and in the Yaquina Bay Estuary near Newport, Oregon. Retrieval and analysis of the Tuckerton fuel cell indicates that power generation results from at least two anode reactions: oxidation of sediment sulfide (a by-product of microbial oxidation of sedimentary organic carbon) and oxidation of sedimentary organic carbon catalyzed by microorganisms colonizing the anode. These results demonstrate in real marine environments a new form of power generation that uses an immense, renewable energy reservoir (sedimentary organic carbon) and has near-immediate application.

Harnessing microbially generated power on the seafloor

Quantifying the degradation of organic matter in marine sediments: A review and synthesis

Marine ecosystems' responses to climatic and anthropogenic forcings in the Mediterranean

The re-eutrophication of Lake Erie: Harmful algal blooms and hypoxia.

The authors report here a test of the hypothesis that the extent of organic matter preservation in continental margin sediments is controlled by the average period accumulating particles reside in oxic porewater immediately beneath the water/sediment interface Oxygen penetration depths, organic element compositions, and mineral surface areas were determined for 16 sediment cores collected along an offshore transect across the Washington continental shelf, slope, and adjacent Cascadia Basin Individual amino acid, sugar, and pollen distributions were analyzed for a 11 to 12 cm horizon from each core, and {sup 14}C-based sediment accumulation rates and stable carbon isotope compositions were determined from depth profiles within a subset of six cores from representative sites Sediment accumulation rates decreased, and dissolved O{sub 2} penetration depths increased offshore along the sampling transect As a result, oxygen exposure times (OET) increased seaward from decades (mid-shelf and upper slope) to more than a thousand years (outer Cascadia Basin) Organic contents and compositions were essentially constant within individual sediment cores but varied consistently with location In particular, organic carbon/surface area ratios decreased progressively offshore and with increasing OET Three independent compositional parameters demonstrated that the remnant organic matter in farther offshore sediments is more degraded Both concentrationmore » and compositional patterns indicated that sedimentary organic matter exhibits a distinct and reproducible oxic effect OET helps integrate and explain organic matter preservation in accumulating continental margin sediments and hence provides a useful tool for assessing transfer of organic matter from the biosphere to the geosphere« less

http://earth.geology.yale.edu/~ajs/1999/07-09.1999.02Hedges.pdf

Sedimentary organic matter preservation; a test for selective degradation under oxic conditions

The study of sedimentary chemistry and its associated proceses is becoming increasingly mathematical. There is a growing desire to gain a quantitative undrstanding of the reasons for the natural chemical changes observed in sediments as they are buried. The aim of this text is to develop transport-reaction (diagenetic) models, and methods for their solution. It attempts to present a detailed account of model formulation by explaining some useful solution techniques. The choice of material illustrates methods that are simple to understand and implement, yet powerful enough to attack even the most complicated diagenetic problems. The cited computer programs are available on the Internet.

Bernard P. Boudreau

Papers

Diagenetic Models and Their Implementation: Modelling Transport and Reactions in Aquatic Sediments