Environmental Engineering Reference
In-Depth Information
Important chemical forms
:
Nitrogen
:
Dissolved inorganic nitrogen
: Ammonium: NH
4
+
-N, Nitrate:
NO
3
-
N, Nitrite: NO
2
-
-N
Total nitrogen (TN)
: All digestible forms of nitrogen (dissolved
and particulate organic and inorganic nitrogen)
Total Kjehdahl Nitrogen (TKN)
: The sum of organic nitrogen
and ammonium nitrogen. Commonly measured as part of
permitting requirements for wastewater treatment plant
discharges
Spatial variation within a wetland may be observed between mac-
rophyte beds and open water zones due to differences in
biological activity (Rose and Crumpton
1996
)
Vertical profiles may be observed with higher levels of ammonia
near bottom sediments and release of orthophosphate from
anoxic sediments (Ryder and Horwitz
1995
; Gli
´
ska-Lewczuk
2009
)
Phosphorous
:
Reactive phosphorous
: Phosphates that react with molybdate
without preliminary digestion-mostly orthophosphate, PO
4
3
.
Total reactive phosphorous
is derived from water samples that
have not been filtered, while dissolved or
soluble reactive
phosphorous
(SRP) is derived from samples passed through a
0.45
mfilter
Dissolved inorganic phosphorous
: orthophosphate- basically
the same as SRP
Total phosphorous (TP)
: All digestible forms of phosphorous
(dissolved and particulate organic and reactive phosphorus)
The forms of nitrogen and phosphorous most commonly measured in
water quality monitoring are total nitrogen and phosphorous,
ammonium, nitrate, and orthophosphate/soluble reactive phos-
phate. However, due to the potential for rapid uptake of dissolved
forms of inorganic nutrients, measurement of total fractions has
been proposed as a better option for monitoring and characterizing
nutrient dynamics (Norris et al.
2007
; Trebitz et al.
2007
)
Wetland sediments play a critical role in the cycling of nitrogen and
phosphorous and the reader is referred to Boon (
2006
) and
Mitsch and Gosselink (
2007
) for excellent overviews of wetland
biogeochemistry
μ
