I have reconstructed the isotope ratios of precipitation and lake water, and I have the reconstructed temperature record.
Could I use these to quantitatively calculate the water balance in the past?
Could some palaeolimnologists give some suggestions? Thanks.
You can infer lakewater 18O composition from extracting 18O from cellulose in lake sediments. See Wolfe, Brent B., et al. "Reconstruction of multi‐century flood histories from oxbow lake sediments, Peace‐Athabasca Delta, Canada." Hydrological Processes 20.19 (2006): 4131-4153.
Thanks Daniel, that is very helpful and I will give feedback after I read these papers. Really thanks.
Thanks Andrew for your attention. By the way, may I ask how to distinguish the cellulose from aquatic plant and land higher plant? This is important, cos the latter one could give us the isotope signal of precipitation such as the analysis of tree ring.
you sieve out the coarse fraction of the sediments, as well as look at the ratio of C:N in sediments.
Hi Mingda, Dan, and Andrew - Nice discussion going, here.
What time scale(s) are you interested in Mingda? (for determining past water balance?)
This is crucial to ascertain as the answer will influence which proxy/approach is best suited to the specific question being asked.
On tree-rings and cellulose (as meteoric water d18O proxy) - there are a number of papers that are pointing in this direction, but it is crucial to realize that there are very major complicating factors, tree species, alpha-cellulose isolation method (and how much resin/lignin is in the heart wood cellulose), micro-climate/aspect/soil drainage, etc. Dendrochronologist and dendrochemists largely overcome these challenges by having very large sample depths (i.e. 8 tree per stand, 2-3 cores per tree = thousands upon thousands of samples for a single site record). d18O on cellulose is a tricky analysis as well (high-temperature pyrolysis/conversion? low-temperature pyrolysis? mass 30 interferences/bkg issues). The bulk cellulose in a lake core/sediment might very well be a robust proxy for meteoric water d18O in some instances, but it's dangerous to assume this holds every where.
My strong recommendation would be to have many 'eggs in your basket' - i.e. a multi-proxy approach that is linked into climatic modeling. Lake water balance is very complicated and depends on many many things, hypsometry, bathymetry, lacustrine biosphere, seasonality, carbon cycle effects of change in water balance - the lake's limnology is crucial!
What time scale you're interested in - and what proxies are available to you (laminated carbonate? chara? pollen? muck and mud (i.e. cellulose and clay)? invertebrate shells/carapaces? - are crucial things to know in order to best help you find the best answer to your (very important!) question.
Best,
Travis
Dear Travis,
Thanks for your discussion here. The records of my research is dated back to the last deglaciation, around 16 kyr BP. And as you mentioned, it is important to make it clear where the cellulose come from.
I use the biomarker-based proxies, such as leaf wax and the short chain alkanes hydrogen isotope which may give the information of precipitation and lake water isotope, respectively. One of their advantage is that the source is relatively clear. We call it compound-specific isotope analysis.
Based on this, although we reconstructed the climate using one lake sediment core, we could give a representative climate record in the past.
Best regards,
Dear Mingda, you can use also 13dC fractionation of bulk carbon content on sediments, coupled with Nitrogen data
Hi Turu,
Could you give more details about this? I am not familiar with N element. Just know the C/N may give information about the contribution between terrestrial and aquatic plant.
And d13C of TOC may tell us the paleovegetation information.
Yes, you are right. May be I did not explain correctly, sorry. A nice paper about C/N ratio possibilities is maybe Wilson et al (2005); Quaternary Science Reviews, 24, 2015-2029.
Best regards
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