Slide #1.

THE NITROGEN CYCLE IN SURFACE WATERS
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Slide #2.

PHYTOPLANKTON ELEMENTAL COMPOSITION • • • • • • • • • O 53% C 27% K 6.2% H 5.5% N 4.6% Ca 1.0% S 0.7% Na 0.7% P 0.5% • • • • • • • • • Fe 0.4% Mg 0.4% Zn 0.3% Cu 0.02% B 0.01% Mn 0.009% Co 0.0006% V 0.0006% Mo 0.0001% • Si 0.1%; DIATOMS 20%
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Slide #4.

FIGURE 12-1; N2 IN GREEN LAKE AND BELOIE LAKE
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Slide #5.

N-FIXATION
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Slide #6.

CYANOBACTERIA AND N-FIXATION
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Slide #7.

OTHER MICROBIAL NITROGEN FIXERS • Azotobacter
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Slide #8.

MEROMICTIC LAKES AND N-FIXATION
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Slide #9.

SYMBIOSIS • N-FIXATION OFTEN THROUGH SYMBIOSIS WITH VASCULAR PLANTS e.g. – Alders (wetland plants) – Legumes – Azolla (aquatic fern)
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Slide #10.

AMMONIUM AND NITRATE
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Slide #11.

AMMONIUM • BY-PRODUCT OF DEAMINATION • NH4+ and NH4OH (see p233) pH NH4+ : NH4OH 6 3000:1 7 300:1 8 30:1 9.5 1:1
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Slide #12.

NITROGEN CYCLE
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Slide #13.

NITRIFICATION • NH4+ NO2- Nitrosomonas – Requires O2; wide range of temperature and pH • NO2- NO3- Nitrobacter – Requires O2; warm temperatures and low pH
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Slide #14.

DENITRIFICATION • C6H12O6 + 12NO3- 12NO2- + 6CO2 +6H2O • C6H12O6 + 8NO2- 4N2 + 2CO2 + 4CO3-- + 6H2O
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Slide #16.

REDUCTION IN AN ANOXIC ENVIRONMENT
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Slide #17.

NITRIFICATION AND DENITRIFICATION
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Slide #18.

ORGANIC NITROGEN • DISSOLVED ORGANIC NITROGEN (DON) • PARTICULATE ORGANIC NITROGEN (PON) • DON:PON INCREASES WITH EUTROPHICATION
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Slide #19.

NITRATE AND PON
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Slide #21.

INORGANIC NITROGEN IN WINTERGREEN LAKE
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Slide #23.

NITROGEN CYCLE
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Slide #24.

NITROGEN IN STREAMS
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Slide #25.

NUTRIENT SPIRALLING
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Slide #26.

NITROGEN LOADING
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Slide #28.

NITRATE IN THE CHESAPEAKE BAY
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Slide #29.

Dead Zone summer 2011, USEPA
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