Has anybody faced an issue like that? I have Ca and pH data for an area of decalcified sand dunes. I was quite surprised that massive drop in Calcium levels was not accompanied by the drop in pH. It appears that pH continues to rise in no relation to lime.
The most interesting thing is that it is happening in every habitat type, from foredune to dry heathland area.
I was considering several explanations, and all of them are quite hard to check without further chemical analysis.
Something else is making the sand acidic because removal of shells should cause a decrease in pH. You could do a bioassay to check if microbial respiration is having any effect?
How is decalcified the sand?
What means decalcified exactly?
If is soluble Ca, may be extracted by chelateion
It temains the not soluble. What is the way?
REgards
With regard to sand analysis, decalcification means removal of the shells :-)
Thanks for the suggestion. In this case the sand dunes are probably decalcified in a natural way, as calcium was probably washed down into the soil profile. Or as they are part of moving dunes, most shells were left behind.
Most troubling sample is this one (collected within heathland):
2002 751 mgCa/kg - ph 6.5
2005 100 mgCa/kg - ph 6.9
2008 300 mgCa/kg - ph 7.1
2011 330 mgCa/kg - ph 7.9
2012 4600 mgCa/kg - ph 6.3
2016 182 mgCa/kg - ph 8.0
It doesn't make any sense. In most cases, higher levels of Ca were connected with beach refullation - bringing sand from different location to compensate for loss of local transport due to coastal protection scheme.
Now I wonder, as Andrew said if there was some other factor acidifying the area - I need to check with Nature Reserve documentation if they ever used sulfur to lower pH within the dunes.
I will advise to add some more factors to be monitored during further surveys. For me pH and Ca is not enough - at least for me ;)
That was my thought. I need to check with survey team if they found any changes within vegetation layer. Maybe heather expansion had its part in it? Or neighbouring scrub? Lots and lots of ifs.
I think Henrik idea is right. Some dunes allow the growth of a special vegetation that helps to fix the dunes. So, the pH will not be always the same
That's the case in here, Luis. Aforementioned sand dune holds patches of acid dwarf shrub heath. I've flagged this problem to surveyors and asked if they've seen any rapid increase or decrease in heather cover, or any unusual vegetation nearby. Or changes in land use within close proximity to a site. That should explain it a little bit.
- Badges
- Science topic
- Similar topics
- Biological Science
- Microbiology
- Virology
- Virus