**5. Conclusion**

Conclusion of research results is based in several points, however reduced in samples number and extent too, when referring to very large littorals at Mexico.

Radioactivity in Marine Salts and Sediments 245

k. Then, and based on previous points, we can say that every large sea portion might be suitably characterized by the percentage of K present in their salts. This can be made very easily in any sea of the planet, by picking up samples from the water surface near the coast. If polluting 137Cs radioactivity (γ rays 662 Kev) is found out accompanying natural radioactivity from 40K (γ rays 1461 Kev), the symptom is present of a rather recent polluting event, whose importance or extent might be evaluated at once by means of the ratio of specific activity per gram of sea salt, or litre of water, of polluting, divided by natural radioactivity and multiplying by 100 in order to have a percentage (Bq.137Csx100/Bq40K). This figure should be concernedly in the measure it approaches to 100%, which means same polluting radioactivity than natural one, and probably it might be useful to avoid the social panic. While same calculation applied to marine sediments 60-80 metres depth, should be useful to measure the already existing background polluting radioactivity, the rate of growing and the real possibility to keep

Authors want to express their most sincere appreciation to Dr. Maria Leticia Rosales Hoz, Director of Sea Sciences and Limnology Institute, from the National University of Mexico, as well as to Dr. Vivianne Solís, Researcher in same Institute, for their invaluable help to

Chang, R., (2005). Nature's own Fission Reactor, In: *Chemistry,* McGrawHill Higher Education, 8th Ed., 962, ISBN 0-07-111317-7, Boston, United States of America Choppin G. & Rydberg J., (a) (1980). Naturally occurring Radioactive Elements, In: *Nuclear* 

Choppin G. & Rydberg J. , (b) (1980). Naturally occurring Radioactive Elements, In:

Choppin G. & Rydberg J., (c) (1980). Thermonuclear Reactions and Nucleogenesis, In:

Lavi N., Groppi F., Alfassi Z., (2004). On the measurement of 40K in natural and synthetic

Periañez R. (a) (2004). Testing the behaviour of different kinetic models for uptake/release

Periañez R. (c) (2010). Modelling Radioactivity Dispersion in Coastal Waters, in *Radioactive* 

*Journal of Environmental Radioactivity,* Vol. 73, (2004), pp. 101-115.

(2010), ISBN 978-1-60741-174-1, New York, United States of America

*Chemistry, Theory and Applications*, Pergamon Press 1st Ed., 225, ISBN 0-08-023823-

*Nuclear Chemistry, Theory and Applications*, Pergamon Press 1st Ed., 222, ISBN 0-08-

*Nuclear Chemistry, Theory and Applications*, Pergamon Press, 1st Ed., 197, ISBN 0-08-

materials by the method of high resolution gamma-ray spectrometry, *Radiation* 

of radionuclides between water and sediments when implanted in a marine dispersion model, *Journal of Environmental Radioactivity*, Vol. 71 (2004), pp. 243-259 Periañez R. (b) (2004). On the sensitivity of a marine dispersion model to parameters

describing the transfers of radionuclides between the liquid and solid phases,

*Contamination Research Developments*, Nova Science Publishers, Inc. Ed. 209-267,

make possible this effort to understand what radioactive pollution really means.

it between tolerable limits.

8, Oxford, Great Britain

023823-8, Oxford, Great Britain

023823-8, Oxford, Great Britain

*Measurements,* Vol. 38, (2004) pp. 139-143

**6. Acknowledgements** 

**7. References** 


a. It seems that radioactive pollution started on the planet at 1945, when first world war was finishing, with the first test of nuclear explosion in Alamo Gordo, followed by war actions in Hiroshima and Nagasaki, and few years later a second test in Bikini

b. Since then, a certain number of the so called industrialised countries have performed several tests in different regions of earth, including underground and submarine

c. Also, some accidents in research and power nuclear installations have taken place, notably those in Three Mile Island, USA, Chernobyl, Russia, and lately Fukushima,

d. Due to the fact that sea occupies about 80% of planet surface, every pollutant event has a larger probability to reach the sea than any other continental or insular region,

e. As growing demand of energy started in societies all over the world in XVIII century, when vapour machine was invented, and today nuclear energy seems to be the most powerful and suitable option to fill up energy demand, closely related to economical development, it looks like already existing, man created radioactive background, presents a strong tendency to grow up in future, since we can not neglect the possibility of accidents as such mentioned before, and even deliberate nuclear

f. It is proposed then, a method to size up the importance and growing rate of radioactive pollution all over the world, by comparing the artificial radioactivity of fission product 137Cs, with that of natural radioisotope 40K, both present in marine sediments at 60-80

g. This procedure seems to be much more general than that to detect just 137Cs in some vegetables such as lichens, which concentrate selectively elementary Cs, and it might be

h. In this context, already existing radioactive pollution , seems quite possible to detect as a background in marine sediments, since 137Cs half life is 30.07 years, and so it has decayed a little more than 2 half lives, about one fourth of the initial polluting radioactivity disseminated in 1945, plus the following nuclear tests and accidents. i. Even when mathematical studies about dispersal of polluting radioisotopes have been successfully applied for limited conditions at a very small fraction of the huge sea (Periañez a, 2004), (Periañeza b, 2004), (Periañez c, 2010), it seems that this matter must be verified and treated in a quite empirical way, since natural and polluting

j. In our samples appeared also some other peaks, such as that corresponding to 208Tl (2614 Kev), with very poor resolution in the scintillation counter. Nevertheless, it is indicating the presence of other natural radioisotopes, because it is the last link of the 232Th radioactive chain, in secular equilibrium with its parent and about 11 ancestors decaying at the same rate, before its own decaying to stable 208Pb, with half life of just 3.1 minutes. Then, as a previous link in the chain, it is 228Ac, γ rays emitter with 1459 Kev, and in consequence with possible contribution to 40K peak (energy 1461 Kev) (Lavi, 2004). But as the difference of activity between these two peaks results so large in our samples (40K/208Tl > 10), then the possible contribution of 228 Ac peak (1% branching ratio) to that of 40K (11% branching ratio) results negligible compared with our rather

atoll.

Japan.

nuclear explosions.

explosions as war actions.

a suitable complement to it.

starting from the point it has happened.

meters depth on a great portion of sea bottom.

radioactivity are facts concerning the whole planet.

large calculated statistical variation.

k. Then, and based on previous points, we can say that every large sea portion might be suitably characterized by the percentage of K present in their salts. This can be made very easily in any sea of the planet, by picking up samples from the water surface near the coast. If polluting 137Cs radioactivity (γ rays 662 Kev) is found out accompanying natural radioactivity from 40K (γ rays 1461 Kev), the symptom is present of a rather recent polluting event, whose importance or extent might be evaluated at once by means of the ratio of specific activity per gram of sea salt, or litre of water, of polluting, divided by natural radioactivity and multiplying by 100 in order to have a percentage (Bq.137Csx100/Bq40K). This figure should be concernedly in the measure it approaches to 100%, which means same polluting radioactivity than natural one, and probably it might be useful to avoid the social panic. While same calculation applied to marine sediments 60-80 metres depth, should be useful to measure the already existing background polluting radioactivity, the rate of growing and the real possibility to keep it between tolerable limits.

#### **6. Acknowledgements**

Authors want to express their most sincere appreciation to Dr. Maria Leticia Rosales Hoz, Director of Sea Sciences and Limnology Institute, from the National University of Mexico, as well as to Dr. Vivianne Solís, Researcher in same Institute, for their invaluable help to make possible this effort to understand what radioactive pollution really means.

#### **7. References**


**13** 

*1Germany* 

*2United Kingdom* 

**Utilizing Radioisotopes for Trace Metal** 

**Speciation Measurements in Seawater** 

The chemical speciation of trace metals in seawater is of critical importance to studies in marine biogeochemistry; as such information is essential for interpreting and understanding the chemical reactivity of trace metals in the environment. Foremost in this respect are studies into the role that chemical speciation plays in determining the biological availability (bioavailability) or toxicity of metals to organisms. Research on this topic over the last 30 years has clearly shown that open ocean productivity can be directly limited by iron. Other studies have revealed more subtle effects, such as co-limitation or limitation/toxicity affecting only some phytoplankton species, can occur with other trace metals and lead to controls on the composition of the phytoplankton community. Thus studies addressing

Work on chemical speciation draws on skills and expertise from a diverse range of fields including; analytical chemistry, environmental chemistry, toxicology, geochemistry, genomics, proteomics, biological oceanography, physical oceanography and chemical oceanography. A tool common to all of these fields is the use of radioisotopes to examine the transfer or exchange between chemical species at environmentally relevant concentrations, which would be impossible with conventional analytical techniques. In this role radiotracers have been invaluable in the development of several key discoveries in Chemical and

The development of the Free Ion Association Model (FIAM) and Biotic Ligand Model

 Quantification of the exchange kinetics between different metal species in solution Oceanographic field research requires the ability to work on a moving ship in the ocean and if this was not difficult enough, work on trace metals necessitates the use of ultraclean techniques to avoid the ubiquitous contamination from the ship itself. Combining this with the normal precautions and safe working environment needed for using radioisotopes can present researchers with a formidable challenge. However despite these problems radiotracers have always been a useful tool for marine scientists, both on land

chemical speciation in seawater are of relevance to the entire marine ecosystem.

**1. Introduction** 

Biological Oceanography:

14C measurements of primary productivity

(BLM) for metal uptake kinetics by phytoplankton

The biological utilization of Cadmium by phytoplankton

Iron limitation in the ocean and its impact on primary productivity

Croot, P.L.1,2, Heller, M.I.1, Schlosser C.1 and Wuttig, K.1

*1FB2: Marine Biogeochemistry, IFM-GEOMAR, Kiel,* 

*2Plymouth Marine Laboratory, Plymouth,* 

Vázquez A., (2001), Vertical profile determination of gamma emitting radionuclides with major concentration in Caribbean Sea and Gulf of Mexico, M. Sc. Thesis, *Environmental Engineering,* Veracruz University, Mexico, 2001, pp 23-32
