Geographic gradients

Floeter SR, Behrens MD, Ferreira CEL, Paddack MJ, Horn MH (2005) Geographical gradients of marine herbivorous fishes patterns and processes. Mar Biol 147 1435-1447 Fusetani N (2004) Biofouling and antifouling. Nat Prod Rep 21 94-104... 

Th, Co, and, in some locations, Fe. Surfece-water enrichments are usually caused by rapid rates of supply to the mixed layer via atmospheric deposition or river runoff. Removal usually occurs through relatively rapid precipitation into or adsorption onto sinking particles. Trace elements controlled by scavenging tend to have short (100 to lOOOy) residence times. Since these residence times are less than the mixing time of the ocean, significant geographic gradients are common. 

There are a variety of compilations of the concentrations of many of the chemical elements for both crustal rocks (see above and Volume 3) and for soils (Bowen, 1979 Shacklette and Boerngen, 1984). In the case of soils, the samples analyzed are usually from a standard surface sampling depth, or from the uppermost horizon. Thus, these samples give a somewhat skewed view of the overall process of soil formation because, as will be discussed, soil formation is a depth-dependent process. Nonetheless, the data do provide a general overview of soil biogeochemistry that is applicable across broad geographical gradients. 

Gentry, A.H., Changes in plant community diversity and floristic composition on environmental and geographical gradients, Ann. Missouri Bot. Gard., 75, 1, 1988. 

Rivers transport material in several phases dissolved, suspended particulate and bed load. Physical and chemical processes within an estuary infiuence the transportation and transformation of this material, thereby affecting the net supply of material to the oceans. Several definitions and geomorphologic classifications of estuaries have been reviewed by Pe-rillo (1995). From a chemical perspective, an estuary is most simply described as the mixing zone between river water and seawater characterised by sharp gradients in the ionic strength and chemical composition. Geographic distinctions can be made between drowned river valleys, fjords and bar-built estuaries. They can alternatively be classified in terms of the hydrodynamic regime as ... 

Wishner, K. F., Gowing, M. M., and Gelfman, C. (1998). Mesozooplankton biomass in the upper 1000 m in the Arabian Sea Overall seasonal and geographic patterns and relationship to oxygen gradients. Deep-Sea Res. II45, 2405—2432. 

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