Dear Bill,
similar delta 13-C values (as low as -48%o) have been measured in aquatic
plants growing in karstic rivers or in their spray zone. See Marcenko et al.,
Radiocarbon 31(3), 67-78 (1989).

Kind regards,

Sonja

.......................................
Dr. Sonja Lojen
Department of Environmental Sciences
J. Stefan Institute
Jamova 39
1000 Ljubljana
Slovenia

Tel.: +386 1 5885 393
Fax: +386 1 5885 346
e-mail: [log in to unmask]



Surlignage Automatic digest processor <[log in to unmask]>:

> There are 3 messages totalling 125 lines in this issue.
>
> Topics of the day:
>
>   1. d13C values of freshwater aquatic grasses (2)
>   2. CO2-in-air samples
>
> ----------------------------------------------------------------------
>
> Date:    Mon, 30 Jun 2003 15:45:57 -0600
> From:    Bill Patterson <[log in to unmask]>
> Subject: d13C values of freshwater aquatic grasses
>
> Dear Listmembers,
>
> Has anyone measuring the carbon isotope values of freshwater aquatic
> grasses observed values in the range of -40 to -43”VPDB? If you have
> observed such values, what is the explanation for such low values
> (methanogenesis)?
>
> Cheers,
> Bill
> --
> Dr. William P. Patterson
> Associate Professor
> Department of Geological Sciences
> 114 Science Place
> University of Saskatchewan
> Saskatoon, SK S7N 5E2 CANADA
>
> Office phone: 306-966-5691; Lab phone 306-966-5712; Cell phone
> 306-220-0046; FAX: 306-966-8593
> Email: [log in to unmask], Web: http://128.233.87.242/bill.html
>
> ------------------------------
>
> Date:    Mon, 30 Jun 2003 15:14:58 -0700
> From:    Rick Doucett <[log in to unmask]>
> Subject: CO2-in-air samples
>
> Hello all,
>
> If anyone can help out Jessica (see message below), I'm sure she would
> appreciate it.  Our GasBench won't be installed for another couple weeks.
>
> P L E A S E respond directly to her ([log in to unmask]), as she is
> not on the ISOGEOCHEM list.
>
> Cheers,
> Rick
>
> >Date: Mon, 30 Jun 2003 14:59:22 -0700
> >From: Jessica Cable <[log in to unmask]>
> >Subject: Re: gasbench
> >To: Rick Doucett <[log in to unmask]>
> >Reply-to: [log in to unmask]
> >
> >Hi Rick,
> >I am collecting CO2 samples tonight in 12mL exetainer vials.  Our gas
> >bench is not working right now.  I will overpressurize my samples and
> >cross my fingers that they will keep.  I have to run them ASAP which is
> >why I called you, hoping your lab is equipped with a gas bench.
> >Thank you for your prompt response!
> >Regards,
> >Jessie Cable
> >**************************************************
> >Jessica M. Cable
> >Graduate Student
> >Department of Ecology and Evolutionary Biology
> >University of Arizona
> >Tucson, AZ  85721
> >(office)520-621-8220
> >[log in to unmask]
>
> Rick Doucett, PhD
> Colorado Plateau Stable Isotope Laboratory
> Department of Biological Sciences
> Northern Arizona University
> Building 21, South Beaver St.
> Flagstaff, AZ, 86011-5640
>
> Tel: 928-523-0967
> Fax: 928-523-7500
> Email: [log in to unmask]
> NEW WEBSITE: http://www4.nau.edu/cpsil/
>
> ------------------------------
>
> Date:    Mon, 30 Jun 2003 23:19:38 +0100
> From:    Andrew M Johnston <[log in to unmask]>
> Subject: Re: d13C values of freshwater aquatic grasses
>
> On 30 Jun 2003, at 15:45, Bill Patterson wrote:
>
> > Dear Listmembers,
> >
> > Has anyone measuring the carbon isotope values of freshwater aquatic
> > grasses observed values in the range of -40 to -43”VPDB? If you have
> > observed such values, what is the explanation for such low values
> > (methanogenesis)?
>
> Hi Bill,
>
> -40 to -43‰ is not so far fetched for just regular photosynthetic
> fixation of CO2 based on pure CO2 diffusion as the mechanism of
> inorganic assimilation. It is probable that the dissolved CO2 is
> slightly more negative than atmospheric CO2 would give in an air
> equilibrated system. The d13C values of freshwater macrophytes is
> near impossible to analyse without some indication as to what the
> d13C of the DIC is. Do you have any data on these?
>
> If you look through some of John Raven's recent papers you are
> likely to come across some similar values for a range of freshwater
> macrophytes.
>
> Hope this helps.
>
> Get back if you think I can help more.
>
> Yours
>
> Andrew Johnston.
> Dundee
>
> ------------------------------
>
> End of ISOGEOCHEM Digest - 28 Jun 2003 to 30 Jun 2003 (#2003-132)
> *****************************************************************
>