Dear all,
  I would like to add to what has been discussed in the below
message. We also have experienced in small and shallow lakes (both,
natural and man-made) in south India the phenomenon of poor horizontal mixing
in the lake waters and good mixing vertically.

Only in case of fairly deep lakes the phenomenon of seasonal stratification
was observed and that gets broken in winter (i.e., winter overturn) in most of
Indian lakes. WE have published a few papers in journals like HYDROLOGICAL
PROCESSES, Applied Radiation and Isotopes, Current Science etc and reprints
of a few of them was sent a few list memebers on request recently.

[Also to mention that, the same phenomenon of seasonal stratification, which
is temperature induced in most of Indian natural and man-made lakes, is being
used now-a-days not only in water balance, dynamics and lake-gw interaction
related studies but also is extended in understanding/diagonising
reservoir/lake seepage/leakage related problems. Our centre has wide
experience on this area of isotope hydrology.

Best Regards,
U. Saravana Kumar
BARC, Mumbai

**********************************************************************
U. Saravana Kumar B.E., M.Tech., Ph.D.,
Scientific Officer 'F'
Isotope Hydrology Section
Isotope Applications Division
Bhabha Atomic Research Centre
Trombay- 400 085. Mumbai. INDIA

Tel: 91-022-2559 2418 (Off.)
     91-022-2558 7082 (Res.)
Fax: 91-022-2550 5151

Email:[log in to unmask] (Per.)
      [log in to unmask] (Per.)
************************************************************************

On Thu, 5 May 2005, Forizs Istvan wrote:

> Dear Professor Gonfiantini, dear Roberto,
>
> thank you very much for your valuable comment!
>
> My opinion is the same as your one regarding the vertical isotopic
> stratification of very shallow lakes like the Balaton. Most probably
> there is no stratification.
> It is very interesting what you wrote about the horizontal zoning
> (insufficient mixing). That is one of my ideas that the horizontal
> mixing is not good enough in the case of Balaton, because the lake
> (along the southern shoreline) is very shallow even at 1000 meters
> offshore (70 cm). It is a pity that there is no data about the
> horizontal inhomogeinity of d18O values of such shallow lakes in the
> literature.
> I will ask Rank about his experience on Lake Neusiedl.
>
> Best regards
> Istvan Forizs
>
> Roberto Gonfiantini wrote:
>
> > Dear Dr Forizs,
> >
> > Isotopic stratification in lake waters is known to occur in summer, when
> > the thermocline prevents vertical mixing and therefore surface water
> > becomes slightly enriched in heavy isotopes. This has been observed in
> > many
> > cases, but not much is reported in the literature.
> >
> > However, in the case of a shallow lake as Lake Balaton, I believe that
> > you
> > cannot expect such a stratification: winds are usually sufficient to keep
> > the water column well mixed. You may rather expect that horizontal mixing
> > is insufficient. For example, a difference in isotopic composition was
> > observed in a similar lake, the Neusiedlersee (which is also not too far
> > from Lake Balaton), between a zone of reeds and the open lake: in reeds,
> > during summer the water was more enriched in heavy isotopes of about
> > 10-15
> > per mil in deuterium, which corresponds to about 2-3 per mil in O-18.
> > (Zimmermann & Ehhalt (1970): Stable isotopes in the study of water
> > balance
> > of Lake Neusiedl, Austria. In: Isotope Hydrology 1970, IAEA, Vienna,
> > pp.129-138). This enrichment can be explained theoretically, but
> > essentially is due to the fact that reeds hinder horizontal mixing.
> >
> > I do not know whether this helps to explain your data. If however you
> > want
> > to compare with the situation in Lake Neusiedl, I suggest you to get in
> > touch with Dr. Dieter Rank in Vienna ([log in to unmask]).
> > Dieter has
> > continued to study the Neusiedlersee and he should be able to tell you
> > more, and provide his publications on the lake (whose references I do not
> > have at hand, in this moment).
> >
> > Roberto Gonfiantini
> >
> >
> >
> > At 08.21 27/04/2005 +0200, you wrote:
> >
> >> Dear Listmembers,
> >>
> >> could any of you tell me a publication about the vertical d18O profile
> >> of lake water (if there is any)?
> >> I think that during strong evaporation the uppermost warm water layer is
> >> enriched in 18O, but I do not know any published data.
> >>
> >> Best regards
> >> Istvan Forizs
> >>
> >>
> >> --
> >> -------------------------------------------------------------------------
> >>
> >> Dr. FÓRIZS István ......... Istvan FORIZS Ph.D.
> >> Magyar Tudományos Akadémia, Geokémiai Kutatóintézet
> >> Institute for Geochemical Research, Hungarian Academy of Sciences
> >> Cím/Address: H-1112 Budapest, Budaörsi út 45.   Hungary
> >> Tel./Phone: (36-1)-309-2600/ mellék/extension 1151
> >> Fax: (36-1)-319-3137
> >> Http://www.geokemia.hu/people/forizs_hu.html
> >> -------------------------------------------------------------------------
> >>
> >
> >
> > Prof. Roberto Gonfiantini
> > Istituto di Geoscienze e Georisorse
> > Institute of Geosciences and Georesources
> > Area della Ricerca del CNR
> > Via G. Moruzzi, 1
> > I-56124 Pisa
> > Italy
> > Phone +39-050-315-2358
> > e-mail [log in to unmask]
> >
> >
>
> --
> -------------------------------------------------------------------------
> Dr. FÓRIZS István ......... Istvan FORIZS Ph.D.
> Magyar Tudományos Akadémia, Geokémiai Kutatóintézet
> Institute for Geochemical Research, Hungarian Academy of Sciences
> Cím/Address: H-1112 Budapest, Budaörsi út 45.   Hungary
> Tel./Phone: (36-1)-309-2600/ mellék/extension 1151
> Fax: (36-1)-319-3137
> Http://www.geokemia.hu/people/forizs_hu.html
> -------------------------------------------------------------------------
>