"Carsten Troelsgaard" <carsten.troelsgaard@mail.dk> skrev i en meddelelse
news:41e803d3$0$161$edfadb0f@dread14.news.tele.dk...
> Undskyld sproget.
> Originalen oprindelig postet til sci.geo.geology og sci.environment.waste
> Lokaliteten er dansk.
>
>
> Phosphorous has been a subject lately and I've popped a link (I lost it)
> to
> a page showing possible commercial exploitation of phosphorous-layers from
> a
> lakebottom, the phosphorous naturally accumulated frow sewage. I have a
> rather long post that deals with an observation of mine that I would like
> comments on.
> The overall picture is, that I met a solid bottom where I didn't expect it
> along a stream with soft and muddy banks I went fishing at last summer.
> Could this be a precipitate?
> The stream follow the bottom of a glacial 'tunnel-vally' cut into soft
> chalk
> and with flat somewhat extensive fluvial deposits. The vally floor is
> largly
> meadow, or differentiated wetland with local peat and occationally used
> for
> grasing livestock. Draining attemts set in 40-50 years ago. The solid
> bottom
> I mention is very local (a few meters), and judged on my 45 years of
> experience on fishing the stream, it is located at a place that should be
> dangerously soft (from a fishers perspective).
> The closest farmhouse is 2-300 m away, at the foot of the vally-side. It
> was
> a very small farm when I was a kid, but grew into a recreational residense
> 20 years or more ago. But a draining-ditch leads perpendicular from the
> neighborhood of the farm toward the stream, and ends somewhat abruptly
> before reaching it (subsurface drain?).
> I estimate the position of the 'precipitate' as following the contour of
> the
> fair-weather watertable or slightly lower, 10 - 15 cm below the
> soil-surface. The 'precipitate' had a smooth surface.
>
> I've previously posted links to iron-ore-bog that may precipitate in a
> somewhat eqvivalent manner or position. I wonder weather the presence of
> modest iron-precipitates may encourage phosphorous-compounds () to
> precipitate.
>
> This link indicates that orthophosphate binds to ferrihydrite.
>
>
http://www.hope.edu/academic/chemistry/research/students/2003/mentzer/
>
> I'm keen on returning for a sample, but in the meanwhile: Any suggestions?
> And how do I evaluate the chemistry of the sample?
Jeg er lige kommet retur fra lokaliteten. Jeg kunne ikke finde det
pågældende sted, men kun at å-bredden var så blød og gyngende som sådanne
ofte er. Positionen af den grøft der leder mod stedet har jeg estimeret
forkert - der er ingen. Min første indskydelse af at stå på en meget lokal
men fast sandbund kan altså ikke forklares som en sedimentering fra en nu
omdirigeret afstrømning fra et kildevæld i nærheden.
Jeg konkluderer, at jeg må have stået på et begravet brædt/plade eller
lignende ..
Carsten
Carsten