I am engaged in a discussion in which there is a dispute regarding the capability for wetlands to remove phosphorous from water. Some say that wetlands are extraordinarily efficient at removing phosphorous and others beleive that only small amounts of uptake occur. Can you help me with the real answer and do you know of references. Thanks.

In Orlando, the wetlands use SAV to remove Phosphorous. Specifically, coon tail and Southern Naiad and adequately removes phosphorous.

quote:

Originally posted by Gary Pierce:
I am engaged in a discussion in which there is a dispute regarding the capability for wetlands to remove phosphorous from water. Some say that wetlands are extraordinarily efficient at removing phosphorous and others beleive that only small amounts of uptake occur. Can you help me with the real answer and do you know of references. Thanks.

What is SAV?

Submerged Aquious Vegetation

quote:

Originally posted by Andrew Geffert:
What is SAV?

Hi Gary -
Here is my understanding of phosphorus in wetlands. Generally phosphorus is adsorped by soil particles, and wetland substrates can only hold a limited quanity of phosphorus. However, since wetlands are also sites were sediment accretes, there may be additional capacity to absorb phosphorus as subsrates buildup. If the rate of sediment accretion is greater than the rate of phosphorus absorption, then wetlands can store phosphorus. Plants, as you know, will use (store) nutrients, but may release nutrients after the plants die-off. After many years of analyzing surface water quality in NC, I have found phosphorus concentrations are generally low ... particularly after the phosphate ban in late 1980s. As for references, Kadlec and Knight may have disscussed this in their Treatment Wetlands book. I wonder, does your discussion also include issues with nitrogen and nitrification and denitrification rates? I wonder how L-Lake is doing?

I am also interested in this question and would like to help re-focus. I believe that what Gary was asking was about the ability of plants to absorb phosphorus directly from the water column and not plant uptake through the soil. Is this correct Gary?

Gee, I am not sure just what Gary was interested in. I thought he was interested in the capacity (or ability) of wetlands to retain phosphorus, since nutrient retention (or transformation as in the case with nitrogen) is a function of wetlands. Wetlands are often built for this purpose. There is some information on the internet on phosphorus and wetlands.

I have a list of references that you may find useful. If you get me a fax number I can fax the list to you. I tried to e-mail you with the list but the e-mail was returned. Plants are generally not very effective at phosphate uptake. Denham Springs, a town in Louisiana (which may not be there anymore) had a stormwater system that used wetlands to clean the stormwater. They found that the plants contributed almost nothing, so they pulled them up and used the soil. Wetlands are most effective at phosphate retention when the phosphate comes in already bound to sediment which gets deposited in the wetland.

Hope this is helpful.

P.S. I took your plant id course a couple of years ago and really enjoyed it!

Your responses have been helpful, and they do not contradict my own interpretation of the literature. I am interested in understading all of the important ways in which a wetland can permanently or temporarily retain P.
Steve it is good to hear feom you; the last I know of L-lake it is a diverse and healthy BBC - Osprey, eagles, beaver, waders, alligators, fish, and otter.