Trace Metal Cycling

From a practical standpoint, stream fulvic acids which comprise over 90% of the stream humic substances are not an important food source for aquatic organisms, but all stream humic and fulvic acids are positive influences on biological growth in respect to phosphorus and nitrogen nutrient cycling, trace metal availability, and limiting potential metal toxicity. 

Barnes, R.S. Schell, W.R. Physical Transport of Trace Metals in the Lake Washington Watershed. In Cycling and Control of Metals, Proc. of an... 

Galloway, J. N. (1979). Alteration of trace metal geochemical cycles due to the marine discharge of wastewater. Geochim. Cosmochim. Acta 43, 207-218. 

Lantzy, R. J. and Mackenzie, F. T. (1979). Atmospheric trace metals global cycles and assessment of man s impact. Geochim. Cosmochim. Acta 43,511-525. 

Driscoll CT, Otton JK, Iverfeldt A. 1994. Trace metals speciation and cycling. In Moldan B, Cemy J, editors. Biogeochemistry of small catchments a tool for environmental research. Chichester, England J Wiley Sons, p. 299-322. 

Table 6.3. Treatment levels of trace metals in the two Israeli arid soils incubated under the field capacity and wetting-drying cycle moisture regimes...

The enhanced chemiluminescence associated with the autoxidation of luminol (5-amino-2,3-dihydro-1,4-phthalazinedione) in the presence of trace amounts of iron(II) is being used extensively for selective determination of Fe(II) under natural conditions (149-152). The specificity of the reaction is that iron(II) induces chemiluminescence with 02, but not with H202, which was utilized as an oxidizing agent in the determination of other trace metals. The oxidation of luminol by 02 is often referred to as an iron(II)-catalyzed process but it is not a catalytic reaction in reality because iron(II) is not involved in a redox cycle, rather it is oxidized to iron(III). In other words, the lower oxidation state metal ion should be regarded as a co-substrate in this system. Nevertheless, the reaction deserves attention because it is one of the few cases where a metal ion significantly affects the autoxidation kinetics of a substrate without actually forming a complex with it. 

We can see that the content of trace metals in water extraction is very low. This means that the direct involvement of these metals in biogeochemical cycles is very restricted. The significant increase of metal contents in acid-soluble form was shown only for Fe, Mn and, partly, for Zn. These data testify the importance of atmospheric deposition for the Arctic ecosystems as a source of nutrients. 

A high amount of various nutrients and trace metals is retained in peat and dead plant residues and thus temporarily eliminated from the biogeochemical cycles and pollutants exposure to human and ecosystem health. The period of this elimination depends on the solubility of these metals. It has been shown (Dobrovolsky, 1994) that... 

However, only the smallest part of soluble metals is involved in the biological cycle. Most of these are either lost to water runoff, or retained in the peat organic matter. The latter is the source of gradual remobilization but the whole mineralization may last up to 50 years or even more. The total accumulated retained amount of macro-or trace metals in organic matter of peat is tens and hundreds of time higher than the concentration of annually released soluble forms, which are available for plants. 

The different metal uptake by plants is accompanied by a different involvement of these trace metals and macronutrients in the biogeochemical cycles. A comparison of... 

The systematic removal of elements by runoff and the reimmobilization from solution by organic matter are continuously counterbalanced by the new input of chemical species, which maintain both biological and biogeochemical cycles. The main sources of water-soluble elements are oceanic aerosols deposited on the land surface and the weathering of rocks. The airborne input of the trace metals may be ranked as follows for the Spitzbergen island ecosystems (Table 4). 

---