Biological tracer element

Lanthanum compounds are used as biological tracer elements. The lanthanum ion has about the same size as the calcium ion and can replace it in, for instance, nerve... 

Be, and °Be. Radioisotopes of hydrogen and carbon are of particular interest because they are major biological elements, and thus can be used as both chemical and biological tracers. Recently, particle reactive Be = 53.3 day) has been utilized as a valuable coastal tracer of short-term particle deposition and remobilization. ... 

Stable isotope analysis (SIA) method uses the stable isotope ratios of various elements as biological tracers. Human and animal body tissues are composed of elements that are ingested through food or water. The isotope ratios of stable isotopes of some of these elements (e.g., C, N, S, O, H, Sr, and Pb) from food and water are preserved in bone and teeth. Therefore, we can measure the isotope ratios of those elements in bone and teeth and then, by comparing those values to known isotope values of possible foods and water sources it is possible to determine aspects of past diets (palaeodiet) as well as the location where that human or animal consumed the food and water (migration). 

Give an account of the role of tracer elements in biological systems. 

The biogeochemical processes that generally describe the interaction of elements with particles are quite well known dissolution, flocculation, ion exchange, sorption, (co)precipitation, electron transfer, and biological uptake. In aquatic environments these reactions often occur simultaneously and competitively. In order to utilize marine tracers effectively, we must understand how elements are associated with particles and sediments. 

Tracer techniques are used widely in biology. Botanists, for example, work to develop new plant hybrids that grow more rapidiy. One common way to determine how fast plants grow is to measure how quickly they take up elemental phosphorus from the soil. New hybrids can be planted in a plot and fertilized with phosphoras enriched 32 32... 

These studies introduce and utilize a natural biogeochemical tracer of sedimentary processes. The use of 210Pb to trace deep ocean currents where flocculent material is transported in one region and deposited in another may provide valuable information on deep sea transport. However, more work is required to verify these initial findings. Additional work also is needed to evaluate mechanisms responsible for the differences in diffusion of certain elements in sediments compared to lead and to identify if two types of biological mixing may indeed be responsible for the high sedimentation rates found in the deep ocean. 

CARRIER. (I) A neutral material such as dialomaceous earth used to support a catalyst in a large-scale reaction system. (2) A gas used in chromatography to convey the volatilized mixture to be analyzed over the bed of packing that separates the components. (3) An atomic tracer carrier a stable isotope or a natural element lo which radioactive atoms of the same element has been added for purposes of chemical or biological research. 

Over periods of years, resorption of lead from storage in bone gives a longer apparent biological half-life to lead in blood. No tracer experiments with lead have continued for a long enough time to evaluate the entry into blood of resorbed lead. On the assumption that the rates of resorption of lead are similar to those found with Sr and other alkaline earth elements, compartmental analysis suggests that resorbed lead may contribute 40% of the input to blood when exposure has lasted for 50 a (Chamberlain, 1985). 

The role of metals and other elements in the health of humans, animals, and plants continues to be of great interest both on a routine basis and in research. Two recent reviews described the important impact of ICP-MS in biomedical research [227, 228]. ICP-MS provides the ability to measure multiple elements at ultratrace levels rapidly and to measure isotope ratios at low enough concentrations so that stable isotope tracers can be used for biomedical research [229]. Much remains unknown about the role of metals and their speciation on biological activity, in large part as a result of inadequate measurement techniques. 

Use of stable isotope dilution to assay elemental concentrations in biological samples has increased markedly in the recent past. Part of the reason is that use of radioactive isotopes previously employed as tracers has declined, and part is that interest in the effect of various elements on biological systems and their fate once they enter the food chain has increased. This important field is far from the author s area of expertise, so what follows should be considered a rather haphazard survey... 

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