1. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s1 Rich Axler, NRRI-UMD Senior Research Associate Grad Faculty: Water Resources Science Grad Faculty: Integrated Biosystems raxler@d.umn.edu 218-788-2716 Wetland Biogeochemistry: Major ions, nutrients = N Biology 5870 Sep 24, 2015

2. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s2 I. Wetland biogeochemistry (mostly about nutrients (N,P)  Biogeochem is about the transport and transformations of chemicals  Can talk about input-output mass balances  the wetland is a box (sources & sinks)  What goes on inside the box determines how it functions WETLAND/LAKE PHOSPHORUS BUDGET

3. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s3 Anaerobic Aerobic Source, Sink, or Transformer? Rates (mass/area/time, mass/volume/time, or mass/time) = Dynamic versus Pools (mass, or concentration [mass/volume or mass/area) = Static

4. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s4 Water chemistry (biogeochemistry): Gases, major ions & nutrients  Gases  Oxygen (O 2 )  Carbon dioxide (CO 2 ) – dissolves in water to form carbonic acid H 2 CO 3, then fractionates to HCO 3 - + CO 3 -2 + CO 2 according to pH of the water  Nitrogen (N 2 )  Hydrogen sulfide (H 2 S)  Major ions: anions HCO 3 -, SO 4 -2, Cl - ; cations Ca +2, Mg +2, Na +, K +  Nutrients (nitrogen and phosphorus)  Trace (micronutrient) metals, vitamins, etc

5. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s5 Additional nomenclature  Dissolved (soluble) versus particulate What type of filter, net, or screen to use And organic versus inorganic

6. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s6 Gas solubility  Maximum amount of gas that can be dissolved in water (“~” 100% saturation) determined by temperature, dissolved ion concentration, and elevation  solubility decreases with temperature “warm beer goes flat”  solubility decreases with higher dissolved ion content (TDS, EC25, salinity) “DO saturation is lower in saltwater than freshwater (for the same temperature, solids “drive out” gases) Why does elevation affect the concentration of dissolved gases?

7. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s7 O 2 variability  Diel (24 hr) variation due to ____________?  Seasonal variation due to _____________ ?

8. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s8 Short-term variability- Hypereutrophic Halsteds Bay, L. Minnetonka, MN Productive Bay Temp Red = warmO 2 Black = anoxic This is a month of 6hr data from an 8m deep bay. Similar patterns have been found in algal mats (millimeters), shallow wetlands and ponds (centimeters), tidal flats, etc. What factors control the DO depth and time pattern?

9. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s9 Seasonal DO variability (Apr-Oct) SKIP Black = anoxia Green = high DO or depth into sediments in cms

10. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s10 Water chemistry: O 2  ~ 21% of air  Very soluble (DO)  Highly reactive and concentration is dynamic  Involved in metabolic energy transfers (PPr & Rn)  Major regulator of metabolism (oxic-anoxic)  Aerobes (fish) vs anaerobes (no-fish, no zoops)  Types of fish - Salmonids = high DO (also coldwater because of DO) - Sunfish, carp, catfish = low DO (also warmwater)  Types of invertebrates Types of plants - Stoneflies = high DO- cattails, bulrushes, reeds, rice - Tubificids = low DOvs alders, cedars, and upland plants

11. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s11 Major sources of O 2  Sources  Photosynthesis (phytoplankton, periphyton, macrophytes)  Air from wind mixing  Inflows  tributaries may have higher or lower DO  groundwater may have higher or lower DO  Diffusion between layers (surface to bottom and vice versa)  Diffusion from plant roots (and stems?)

12. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s12 Emergent plant adaptations Cattail roots from subsurface flow gravel bed constructed wetland – 3 ys old (domestic septic tank effluent [NERCC Cell 1]) Even dead, cattails pass O2 the wet substrate - directly, and by venturi- induced (wind) convection. Other adaptations to low O 2 ??

13. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s13 Major sinks of O 2  Sinks  Respiration  bacteria, plants, animals; water and sediments  Diffusion to sediment (respiration deeper)  Outflow (tributary or groundwater)  Chemical oxidation (abiotic)

14. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s14 O 2 : Human significance SKIP for lecture  Not a direct threat to humans  Directly affects fish physiology and habitat  Indirectly affects fish and other organisms via toxicants associated with anoxia: H2SH2S  NH 4 + (converts to NH 4 OH and NH 3 above ~pH 9)  Indirectly affects domestic water supply  H 2 S (taste and odor)  Solubilizes Fe (staining)  Indirectly affects reservoir turbines  Via H 2 S corrosion and pitting (even stainless steel)  Via regulation of P-release from sediments (mediated via Fe(OH) 3 adsorption)

15. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s15 Gases: N 2  ~ 78% of air  Concentrations in water usually saturated because it is nearly inert  Supersaturation (>100 %) can occur in reservoir tailwaters from high turbulence  May be toxic to fish (they get “the bends)  N 2 -fixing bacteria and cyanobacteria (blue-green “algae”) convert it to bio-available NH 4 +  Denitrifying heterotrophic bacteria convert NO 3 - to N 2 and/or N 2 O under anoxic conditions  neither N2 fixation nor denitrification typically affects overall N2 levels

16. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s16 Gases: CO 2 SKIP  Only about 0.035% of air (~ 350 ppm)  Concentration in H 2 O higher than expected based on low atmospheric partial pressure because of its high solubility Gas (at 10 o C) Concentration @ 1 atm (mg/L) Concentration @ normal pressure (mg/L) N2N2 23.318.2 O2O2 55.011.3 CO 2 23190.81 How long does your soda pop fizz after shaking it?

17. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s17 Water chemistry – Major ions SiO 2 < 1 Note: plant nutrients such as nitrate, ammonium and phosphate that can cause algae and weed overgrowth usually occur at 10’s or 100’s of parts-per-billion and along with other essential micronutrients usually are <1% of the actual amount of cations or anions present in the water which are at levels of 10’s of thousands of parts-per-billion

18. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s18 Anionsmg/LCationsmg/L HCO 3 - 58.4Ca +2 15.0 SO 4 -2 11.2Mg +2 4.1 Cl - 7.8Na + 6.3 SiO 2 13K+K+ 2.3 NO 3 - <1.0Fe +3 ~0.7 Total = ~91.4 anions + ~28.4 cations = ~ 120 mg/L (TDS) Major ion concentrations – freshwater SKIP

19. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s19 Why the focus on N and P? Limiting nutrients – demand versus supply  Nitrogen and phosphorus are typically in extremely short supply in water relative to plant demand  The “Redfield ratio” is the average composition of elements in phytoplankton algae  Ratio – 100DW:40C:7N:1P

20. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s20 Electron Acceptors in Oxidation of Organic Carbon Everyone understands this – right ??

21. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s21 RESPIRATION What’s reduced?- O 2,NO 3 -, Mn 4+,Fe 2+,S 4 2-, and CO 2 [aerobic respiration; anaerobic denitrification, sulfate reduction, methanogenisis etc.] What’s oxidized? Organic carbon (“food”) Who does it? Auto- & Heterotrophs (plants, animals, bacteria) Why? To get energy for cellular metabolism Other important biotic energy producing redox reactions What’s oxidized?- NH 4 +, S 2- oxidation, Fe 3+, … [nitrification, sulfide and iron oxidization, …) Who does it?- Chemoautotrophs (chemosynthesizers) Why ? To get energy for CO 2 fixation (to make organic-C) Microbial metabolism

22. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s22  Nitrogen is relatively scarce in some watersheds and therefore can be a limiting nutrient in aquatic systems  Essential nutrient (e.g., amino acids, nucleic acids, proteins, chlorophyll)  Key differences from phosphorus  Not geological in origin  Unlike phosphorus, there are many oxidation states II. Nitrogen – basic properties

23. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s23 Nitrogen – biologically available forms  N 2 (gas)– major source, but usable by only a few species  Blue green algae (cyanobacteria) and certain anaerobic bacteria  Nitrate (NO 3 - ) and ammonium (NH 4 +) – major forms of “combined” nitrogen for plant uptake  Also called dissolved inorganic nitrogen (DIN)  Total nitrogen (TN) – includes:  DIN + dissolved organic nitrogen (DON) + particulate nitrogen (PON ~ PN)

24. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s24 Nitrogen – general properties  Essential for plant growth (amino acids/proteins; nucleic acids, chlorophyll, …)  Always important to plant growth and can be “limiting”:  phosphorus enriched lakes, ponds, wetlands  Pristine, unproductive lakes, streams and wetlands located in watersheds with nitrogen-poor soils (Know places like this?)  Estuaries, open ocean (major cause of Gulf “hypoxia” +HABS)  Wetlands with high rates of N-loss relative to inputs  Lots of input from the atmosphere in many regions  Combustion NO x, fertilizer dust, fertilizer aerosols (NH 3 )

25. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s25 Nitrogen – general properties  Mobile – in the form of nitrate (soluble), it goes wherever water flows  Ammonium (NH 4 + ) tends to adsorb to soil particles (usually electronegative but be careful here)  Blue green algae can fix nitrogen (N 2 ) from the atmosphere  Nitrogen has many redox states and is involved in many bacterial transformations

26. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s26 Nitrogen – sources  Atmospheric deposition  Wet and dry deposition (NO 3 - and NH 4 + )  Combustion gases (power plants, vehicle exhaust, acid rain), dust, fertilizers  Streams and groundwater (“mostly” NO 3 - )  Sewage and feedlots (NO 3 - and NH 4 + )  Agricultural runoff (NO 3 - and NH 4 + )  Regeneration from aquatic sediments and bottom water (NH 4 + )

27. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s27 Nitrogen - toxicity  Methemoglobinemia – “blue baby” syndrome  > 10 mg/L NO 3 - -N or > 1 mg/L NO 2 - -N in well water  Usually related to agricultural contamination of groundwater  NO 3 - – possible cause of stomach/colon cancer  Un-ionized NH 4 + can be toxic to coldwater fish  NH 4 OH and NH 3 at higher pHs ( > ~ 9)  N 2 O and NO x – contribute to smog, haze, ozone layer depletion, acid rain, climate change, global dimming

28. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s28 Nitrogen – many oxidation states  Unlike P there are many oxidation states  Organisms have evolved to make use of these oxidation-reduction states for energy metabolism and biosynthesis -30+ 1+ 2+ 3+ 5 NH4+NH4+ N2N2 N2ON2ONO2NO2 NO2-NO2- NO3-NO3-

29. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s29 Nitrogen – bacterial transformations Organic-N NH 4 + -NHeterotrophic ammonification or mineralization. Associated with oxic or anoxic respiration. NH 4 + -N NO 3 - -NInvolves oxygen (oxic). Autotrophic and chemosynthetic ("burn” NH 4 + -N to fix CO 2 ). NO 3 - -N N 2 (gas) Anoxic process. Heterotrophic. ("burn" organic matter and respire NO 3 -, not O 2 ). Also creates N 2 O N 2 (gas) Organic-N Some blue green algae are able to do this. Decomposition Nitrification Denitrification Nitrogen fixation

30. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s30 Nutrients- The Nitrogen Cycle modified from Horne and Goldman. 1994. Limnology. McGraw Hill. Nutrients – nitrogen cycle

31. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s31 Org–N N 2 = largest reservoir but cannot be used by most organisms Fixed or available-N organism-N + detrital-N + dissolved organic-N NH 4 + NO 2 - NO 3 - -3+5+4+3+2+1 0 -2 Oxidation state NO 2 N2ON2O N2N2 gases Chemical forms of nitrogen in aquatic systems NH 4 + NO 2 - NO 3 - Dissolved inorganic-N (DIN) Ammonium: basic unit for biosynthesis Nitrite: usually transient Nitrate: major runoff fraction

32. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s32 Functionally in the lab using filters… Total-N = particulate organic-N + dissolved organic-N + particulate inorganic-N + dissolved inorganic-N TN = PN + DON + DIN Dissolved inorganic-N = [Nitrate + Nitrite]-N + ammonium-N DIN = NO 3 -N + NO 2 -N + NH 4 -N Notes: Nitrate+nitrite are usually measured together. Nitrite is usually negligible.

33. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s33 Assimilation (algae + bacteria) Assimilation -3+5+4+3+2+1 0 -2 Oxidation state Assimilation Denitrification NO 2 N2ON2O N2N2 NH 4 + NO 2 - Mineralization Org-N Main N-cycle transformations N 2 - Fixation - Soil bacteria - Cyanobacteria - Industrial activity - Sulfur bacteria Denitrification (anoxic bacteria) Nitrification 1 (oxic bacteria) Nitrification 2NO 3 - Ammonification gases Anammox (anoxic bacteria)

34. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s34 Surficial Sediments N2N2 Algae/Plants oxic anoxic NO 3 - NH 4 + Nitrification Assimilation Mineralization NH 4 + Nitrification NO 2 -, N 2 O NO Denitrification Sedimentation DIN PON DON Sedimentation Deep Sediments Burial Ammonia volatilization Tribs, GW, Precip DON, PON, NO 3 -, NH 4 + NO 3 - Outflow diffusion N 2 -fixation Whole lake/wetland N-budget Mixing Mineralization

35. Developed by: R.Axler and C. Hagley Draft Updated: January 13, 2004 U1-m2/3Part 5-s35 Wetland plants: importance to N- cycling Supply O 2 to root rhizosphere Aerobic vs anaerobic interface Enhanced nitrification (with O 2 ) Enhanced denitrification (without O 2 via nitrate production) Assimilate nitrate and ammonium (temporary storage) Source of DOC to microbial communities in root zone Enhanced O 2 depletion and bacterial activity in general Stabilize sediments (reduce N-loss via flushing and erosion) Plants and plant litter may affect temperature ( + or - ??)