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Benthic-pelagic coupling are processes that connect the benthic zone and the pelagic zone through the exchange of energy, mass, or nutrients. These processes play a prominent role in both freshwater and marine ecosystems and are influenced by a number of chemical, biological, and physical forces that are crucial to functions from nutrient cycling to energy transfer in food webs.
Isotope exchange reactions play an important role for the stable isotope geochemistry and for the experimental study of sulfur transformations using radiotracers. Microbially catalyzed processes are partly reversible whereby the back-reaction affects our interpretation of radiotracer experiments and provides a mechanism for isotope fractionation.
As with oceans, the benthic zone is the floor of the lake, composed of accumulated sunken organic matter. The littoral zone is the zone bordering the shore; light penetrates easily and aquatic plants thrive. The pelagic zone represents the broad mass of water, down as far as the depth to which no light penetrates. [9]
The pelagic food web, showing the central involvement of marine microorganisms in how the ocean imports nutrients from and then exports them back to the atmosphere and ocean floor. A marine food web is a food web of marine life. At the base of the ocean food web are single-celled algae and other plant-like organisms known as phytoplankton.
Bioturbation can either enhance or reduce the flux of contaminants from the sediment to the water column, depending on the mechanism of sediment transport. [37] In polluted sediments, bioturbating animals can mix the surface layer and cause the release of sequestered contaminants into the water column.
The location of the top of the sediment-water interface in the water column is defined as the break in the vertical gradient of some dissolved component, such as oxygen, where the concentration transitions from higher concentration in the well-mixed water above to a lower concentration at the sediment surface.
Macrobenthos consists of the organisms that live at the bottom of a water column [1] and are visible to the naked eye. [2] In some classification schemes, these organisms are larger than 1 mm; [1] in another, the smallest dimension must be at least 0.5 mm. [3] They include polychaete worms, pelecypods, anthozoans, echinoderms, sponges, ascidians, crustaceans.
In this type of substitution reaction, one group of the substrate participates initially in the reaction and thereby affects the reaction. A classic example of NGP is the reaction of a sulfur or nitrogen mustard with a nucleophile, the rate of reaction is much higher for the sulfur mustard and a nucleophile than it would be for a primary or secondary alkyl chloride without a heteroatom.