Trace Elements in the Volcanic Waters of Thera and Milos

In Santorini, as well as the hot waters, we have collected and analyzed samples of condensed vapours in the crater always emitting fumaroles and also waters of the caldera. In Milos, we have collected samples of hot spring waters, in five different places.

In Santorini, we have determined the following elements: Sc, Cr, Fe, Co, Zn, Rb, Sr, Cs, Hg, Hf and also lanthanides as the Eu, Yb and Tb. In Milos, we have found the same elements and Ce in hot spring waters.

I. INTRODUCTION

We have studied two volcanoes in the Aegean Sea: we mean Thera and Milos.

In Santorini, there is still a low volcanic activity showed by emanation of fumaroles and hot waters arriving in the caldera which was formed in the eruption of the Minoan period of about 1450 B.C.

In Milos, there are many hot spring waters on the island and round it. In both cases, we have studied several hot springs of the two volcanic islands.

As we are interested in trace elements at the level of ppm and ppb, we have been very careful to collect properly the samples.

The analyses have been done by neutron activation of the liquid samples in a nuclear reactor.

The data of the irradiation are determined with Ge (Li) detectors and a multichannel analyser. A computer makes the semi-automatic analysis of the spectra registered and calculates the data of the elements we present here.

II. SAMPLING

In the hot springs waters, we collect the samples with gloves, with polyethylene syringes. We transfer 2 cc of water in a quartz vial which is sealed immediately on our arrival at the laboratory.

For the vapors of the crater of Santorini, we merely use a funnel in quartz. We put it on the exit of the fumaroles and collect the drops of hot waters at the end of a quartz tube connected to the funnel. 

We proceed by the same way to put the condensed vapors in the quartz vial.

III. ANALYSIS

After the irradiation, we transferred the radioactive waters to a standard container in perspex which can contain about 1 cc. Then we counted the induced activity of the samples on Ge (Li) detectors.

We worked with an Intertechnique Tridac multichannel analyser (16 K memory) and with a PDP system computer for the treatment of the data to obtain the quantities of the elements we found.

IV. RESULTS

The results are presented in tables 1 to 4. (see Appendix).

Many samples were collected during several years from 1967 till 1973, in different places called Steno, Erinia, Aghios Giorgios, Aghios Nicolaos in Santorini and Adamos, Port, Halyk, Kastanas, Paleokori in Milos.

The temperature of the hot springs waters of Santorini was about 37° C.

In Milos we measured up to 65° C in Paleokori.

V. CONCLUSONS

In Santorini, we see the difference between the quality of the hot springs waters and the condensed vapors, specially from the appearance of three lanthanides Eu, Yb and Tb and also Hf.

The analyses of the hot springs waters and the waters of the caldera show that there is a slow dilution of the elements in the surrounding sea water.

In Milos, the samples 1, 2, 3 and 4 show likely the same quality but the sample 5 from Paleokori indicates a high concentration of all the elements and furthermore the presence of Ce, Eu and Tb. This is probably due to the high temperature of the hot spring waters nr 5.

In order to compare Santorini and Milos, we have chosen a sample from Steno in Santorini (0188) and a sample from Paleokori in Milos (nr 5). We are not able to compare condensed vapors from Santorini and Milos because we have not collected condensed vapors in Milos. This is the reason we limited the comparison to show the difference between the quality of the hot spring waters.

We found that the quantities of Cr, Zn and Sr are of the same level. We discovered Se, Fe, Co, Rb, Cs are in higher quantities in Paleokori than in Steno and furthermore the presence of Ce, Eu and Tb in Paleokori.

On the other hand, we did not find traces of Hg in Paleokori; this probably disappeared during the sampling considering, the high temperature of the hot spring waters.

From this study, we may say that the samples collected in a volcanic area are more and more concentrated in elements when the temperature goes up.

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