Hi Linda: Nice to hear from you again. I am sure that the soil and plant
part is NOT the best part of the chapter since it represents a topic that I
have little exposure to. A lot of it came from recent reading, including
your review chapter and Hogberg's, so it shouldn't be too out-of-date, I
hope. But science marches on and reviews can get out of date very fast
sometimes. I would be very interested to learn where you think it is most
problematic. And I would be interested in your comments on our NSF
project. It is entitled "Topographical Linkages Between Nitrogen and
Organic Carbon Solutes", with Myron Mitchell of State Univ. of NY as the
senior PI, and Chris Cirmo, Jeff McDonnell, Sherry Schiff, and I as co-PIs.
It is a study in a forested hillslope above a wetlands in NY.
I would enjoy a visit by you. I will be thinking how to arrange it when
you come to the US in the fall. Maybe you could give talks at a couple
local places, to share the costs. Like UC Berkeley, UC Davis, etc.
--Carol
*******************************************************************************
Carol Kendall tel:
1-650-329-4576
USGS, 345 Middlefield Road, MS 434 fax: 1-650-329-5590
Menlo Park, CA 94025 USA email:[log in to unmask]
"L.Handley"
<[log in to unmask] To: [log in to unmask]
ARI.AC.UK> cc:
Sent by: Stable Subject: Re: 15N - Linda
Isotope Handley's reply
Geochemistry
<[log in to unmask]
UVM.EDU>
04/06/00 08:48 AM
Please respond to
Stable Isotope
Geochemistry
Dear Carol,
I've been reading your 1998 chapter, honest this time! I'm learning a lot
about
what hydrologists have been doing with nitrate and 18O. I'm going to
instigate our
occasional reading discussion group on this topic; we haven't been watching
this
literature at all. I am now even more of the opinion that mutual cross
talk would
benefit both of us. You introductory section on plants and soils seriously
concerns me, especially in view of your new NSF grant---but I'm not sure,
how to
arrange a meeting. Is there any possibility you could come see us after
the
Germany meeting? Alternatively, as I said before, I could try to get out
to Calif.
after I have been to Miami in Oct or Nov.
Cheers,
Linda
Carol Kendall wrote:
> Hi Laura: For a less pessimistic perspective of the uses of N and O
> isotopes in groundwater and surface water studies, you might want to look
> at two other recent reviews of the subject:
>
> Kendall, C., 1998. Tracing nitrogen sources and cycling in catchments,
> Chapter 16, In: C. Kendall and J.J. McDonnell (Eds.), Isotope Tracers in
> Catchment Hydrology, Elsevier, Amsterdam, p. 519-576.
>
> Kendall, C., and Aravena, R., 2000. Nitrate isotopes in groundwater
> systems, Chapter 9, In: P. Cook and Herczeg, A.L. (Eds.), Environmental
> Tracers in Subsurface Hydrology, Kluwer Academic Publishers, p. 261-297.
>
> --Carol
>
>
*******************************************************************************
>
> Carol Kendall tel:
> 1-650-329-4576
> USGS, 345 Middlefield Road, MS 434 fax: 1-650-329-5590
> Menlo Park, CA 94025 USA email:[log in to unmask]
>
> "L.Handley"
> <[log in to unmask] To:
[log in to unmask]
> ARI.AC.UK> cc:
> Sent by: Stable Subject: Re: 15N - Linda
> Isotope Handley
> Geochemistry
> <[log in to unmask]
> UVM.EDU>
>
> 03/24/00 07:21 AM
> Please respond to
> Stable Isotope
> Geochemistry
>
> Laura Vitoria wrote:
> Linda: Thanks for your explanations and the time you consecrate to
> answer my mails. I like also your sincerity in your answers but
there
> are things I don't understand or I don't agree. I am going to work
> with polluted groundwaters with a lot of nitrate (in the ppm range).
> My first objective is to choose two restricted and separated areas
> with different origins of contamination. I'll make a chemical
> characterization, with general chemistry and isotopic chemistry: 34S
> of SO4, 15N of NO3 and NH4 andsurely 18O of SO4 and NO3.The first
area
> will be one of the polluted areas that we have in Catalonia
> contaminated by farm's residues, specifically by pig's farms. It
would
> have to be an area only with this source of contamination.The other
> one would have to be only contamianted by commercial fertilizers.We
> are going to characterize these contaminations sources, and
> groundwaters, and then try to understand the fractionations they
take
> place.Afterwards, we would like to do the same study in a mix area,
I
> mean, where there are both sources of contamination together.
> ------------------------
>
> The key problem with the delta15N is that the isotopic value of the
> samples you measure probably have no relationship with the source
> signature. delta 15N is not a tracer. You may or may not find out
> that the delta 15N of the nitrate in the pig area is larger than the
> delta 15N of the nitrate in the fertiliser area, but the values you
> measure will reflect the microbial and physical processes acting on
> the N before you sample it; it will not have much or anything to do
> anymore with the original source signature; even if you find samples
> that look like values similar to the source signature, you cannot
> assume that it is not just a coincidence. In other words, you may
find
> differences, but you won't know what they mean, and you can't apply
> them to a mixing model and the processes acting on the N in a third
> area won't necessarily be the same as in the other two areas, and
you
> won't have any basis for assuming that they are. Using 18O won't
help
> sort this out. there is not enough known about the process-related
> changes of 18O to make any sense out of it. 18O is a whole new
> research area, even less well understood, at this point, than 15N.
> Neither isotope pair is understood well enough to use in secondary
> applications to problems like you describe.
> -------------------------
> I know that the method of cation/anion exchange columns are one of
> the most common, but we found that the diffusion method of Khan,
S.A.
> (1997), is cheaper and seems to be faster.
> ---------------
> If nitrate is the only major form of N, then it may work fine.
> ------------------------------------
> Also, it seems that it will work for our tipe of samples (have you
> read the article?).If it won't, we will change the method.Even so, I
> looked for the article of Cecily Chang which seems interesting, and
> yours, which I couldn't found. I would be very gratefull if you
could
> send me a copy as you said, because I would like to read it also. If
> you could send it to me in the adress below...
> ----------------------------------
> I sent you a copy some days ago and also a copy of a major review I
> wrote on this subject ; they should be with you soon.
> All the best, and good luck!
> Linda
>
> And also, I think that your invitation to go to learn your method
is
> very nice from you and I will keep it in mind. cheers,Laura Vitoria
i
> Codina Grup Consolidat de Mineralogia Aplicada i Medi AmbientDpt.
> Cristal.lografia, Mineralogia i Dipòsits MineralsFacultat de
> GeologiaUniversitat de BarcelonaC/ Martí i Franqués s/n08028
> Barcelona, SpainTel.34-93-4021345; Fax. 34-93-4021340e-mail:
> [log in to unmask]
|
