Lauren Noble

Professor Weisskoff
First Year Seminar in Social Science
November 2, 2000

               STA - Stormwater Treatment Areas

     "The Everglades is under assault from development and drainage, 
the invasion of exotic species, nutrient over-enrichment
(eutrophication), and mercury contamination." (Mercury Compliance
Report)  But what can we do to help?  Answer: Stormwater Treatment
Areas.  Six STA's exist in the Everglades Construction Project (ECP),
and at the time of this report STA 6 is fully operational.  Located at
the southeastern corner of Hendry County and southwest corner of the
EAA is the STA 6.  Operation of STA 6 began in December 1997 and two
complete years passed in December 1999.  STA 6 has two treatment cells
that are designed to provide a total effective treatment area of 352
ha (870 acres).  Since 1989 the United States Sugar Corporation (USSC)
has operated the two cells as a storm water retention center.  In
order to prevent the operation of STA 6 from interfering with water
management in meeting the demand for agricultural irrigation makeup
water, G600 is at the discretion of the USSC.

        STA's are expected to remove remotely 50 to 75% total mercury
and methylmercury from inflow water and wet and dry deposition based
on the performance of the prototype STA, the ENR project.  "The
mechanisms of removal are most likely sorption to settling and settled
plant litter and the mining of inorganic mercury from the surficial
peat soils by rooted macrophytes that release it to the air as
elemental mercury." (Mercury Compliance Report)  While an in depth
mercury mass budget can't be created for STA 6, the flow-weighted
outflow concentrations of total mercury and methylmercury are less
than those of the inflow over the first two years of operation.  So
there is little likelihood that STA 6 is a net source of total mercury
or methylmercury, even with the input of total mercury in wet and dry
atmospheric deposition.

       The STA's will not decrease the loads and concentrations of
dissolved organic carbon (DOC), calcium, sulfate, chloride, and iron,
all of which are recognized or reasonably anticipated to directly or
indirectly have some bearing on methylmercury production or
bioaccumulation.  This means that in regions of the northern
Everglades where canals discharge influence water and sediment
chemistries, the absolute concentrations of entire phosphorus and
entire mercury in water and sediment will be decreasing, while the
concentrations of these other components will not change
substantially.  The decline in the absolute and relative
concentrations of total phosphorus are likely to effect in
corresponding changes in methylmercury production over time, such that
the bearing areas will advance the conditions that already exist in
the untouched areas farther downstream.

       Further reviews are planned to qualify and quantify the change
of the sulfur cycle on the routes and rates of methylmercury
production and destruction below the conditions existing along the
unnatural sulfur incline in the Everglades.  So many things affect the
Everglades, and hopefully I just informed you of methods that the
government is trying to take in efforts to restore it, with STA's for
example.  As described in the SWIM Projects, a proposal of the
Everglades, the government plans on spending $312 million dollars to
"acquisition, design, and construction of 35,000 acres to treat
stormwater runoff from the EAA and reduce the phosphorus entering the
EPA." (Proposed Everglades SWIM Projects)



                           Bibliography
http://exchange.law.miami.edu/everglades/ -

Major Findings of the 2001 Everglades Consolidated Report
Everglades Consolidated Report; Appendix 7-16 : Mercury Compliance

Report
http://mako.law.miami.edu:80/everlitdb/doc...tive/doah/92_3038/productions/s
wimbl.ht 

- "Proposed Everglades SWIM Projects (Summary)