Arsenic cycling

The range of processes that must be considered in the cycle of metals is described in Fig. 15-10 (Nelson et al., 1977). Both the complexity of metal cycle analysis in a real system and the importance of speciation are well-stated by Andreae (1979) in his overview of the arsenic cycle in seawater ... 

The most important concept with respect to arsenic cycling in the environment is constant change. Arsenic is ubiquitous in living tissue and is constantly being oxidized, reduced, or otherwise... 

Developing appropriate models of arsenic cycling and budgets in natural ecosystems. 

Sanders, J.G. 1980. Arsenic cycling in marine systems. Mar. Environ. Res. 3 257-266. 

Breit, G.N., Foster, A.L., Sanzolone, R.F. et al. (2000) Arsenic cycling in eastern Bangladesh the role of phyllosilicates. Abstracts with Programs. The Geological Society of America, 32(7), 192. 

Ford, R.G., Wilkin, R.T. and Hernandez, G. (2006) Arsenic cycling within the water column of a small lake receiving contaminated ground-water discharge. Chemical Geology, 228(1-3 Special Issue), 137-55. 

Oremland, R.S., Stolz, J.F. and Hollibaugh, J.T. (2004) The microbial arsenic cycle in Mono Lake, California. FEMS... 

Sanders, J.G., Riedel, G.F. and Osman, R.W. (1994) Arsenic cycling and its impact in estuarine and coastal marine ecosystems, in Arsenic in the Environment Part I Cycling and Characterization (ed. J.O., Nriagu), John Wiley Sons, Ltd, New York, pp. 289-308. 

There were 37 distinct enzymes that contain molybdenum or tungsten known by the end of 1997. The enzymes are diverse in function, broadly distributed, and include oxidases, reductases, dehydrogenases, a transhydroxylase, and a hydratase. The Mo enzymes are found in eubacteria, archae, protista, fungi, plants, and animals (including humans) and are essential for respiration and carbon and nitrogen assimilation. Several of the enzymatic substrates and products are key components in the nitrogen, sulfur, selenium, carbon, and arsenic cycles and have major biological and environmental impact. 

Ferguson, J.F. and Gavis, J. A review of the arsenic cycle in natural waters. Water Res. 1259-1274 (1973). 

There is much evidence for arsenic release into shallow sediment pore waters and overlying surface waters in response to temporal variations in redox conditions. Sullivan and Aller (1996) investigated arsenic cycling in shallow sediments from an unpolluted area of the Amazonian offshore shelf. They found pore-water arsenic concentrations up to 300 p.g in anaerobic sediments with nearly coincident peaks of dissolved arsenic and iron. The peaks for iron concentration were often slightly above those of arsenic (Figure 1). The magnitude of the peaks and their depths varied from place to place and possibly seasonally but were typically between 50 cm and 150 cm beneath the sediment-water interface (Sullivan and Aller, 1996). There was no correlation between pore-water arsenic concentrations and sediment arsenic concentrations (Figure 1). 

Kuhn A. and Sigg E. (1993) Arsenic cycling in eutrophic Eake Greifen, Switzerland influence of seasonal redox processes. Limnol. Oceanogr. 38, 1052-1059. 

The arsenic cycle shown below (Irgolic and Martell, 1985) may serve to convey an idea about the diversity of compounds formed by arsenic. 

Islam, M. K., and Islam, M. N., 2001, Arsenic cycling in eastern Bangladesh the role of phyllosilicates Geological Society of America Abstracts with Program, v. 32, no. 7, p. A192. 

The arsenic cycle in ocean waters and sediments also has important biological steps (Andreae, 1979). Arsenate, As(V), can be biologically converted into arsenite, As(III), and at least eight different organo-arsenic compounds, all presumably representing detoxification processes mediated by bacteria in... 

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