411 2003 Chemistry Lecture Slides

1. 411 2003 Chemistry Lecture Slides

2. River Ecosystems(3):river chemistry General conditions affecting River Chemistry • well mixed • chemically homogeneous • except hyporheic environment • thermal stratification rare (occasionally large pools) • generally aerobic environment • favors oxidation • suppresses anaerobic processes • but locally important exceptions (hyporheic, pools, banks, floodplains)

3. Nr311/511

4. Nr311/511

5. Principal dissolved material in freshwater ecosystems Nr311/511

6. Nr311/511

7. Photosynthesis and macro-nutrients 6 HOH + 6 CO2 <=>C6H12O6 + 6 O2 stoichiometrically useful but too simplified

8. a more realistic (but also very simplified) equation for the production • of plant (algae) protoplasm: • 106 CO2 + 16 NO 3-+ xPO4 + 122 HOH + 18 H + ENERGY<=> (C106H263O110N16P1) + 138 O2 • note molar ratios of 106:16 ( ~12:1) C to N and 16:1 N to P • correcting for molar weights • Necessary Inputs atomic wt mg per mole algae wt relative to P • CO2-C ~12 1272 ~41 • NO3-N ~14 224 ~7 • PO4=-P ~31 31 1 • Energy

9. How much is a lot?

10. 50 ppb 10 ppb 100 What is average?

11. Examples of some chemically distinct waters Nr311/511

12. River Ecosystems(3):river chemistry • …three ways to look at dissolved materials: • load or loading [mg/sec or g/day or kg/yr] • can standardize loading by area: • yield [e.g. mg/sec/sq mile or g/day/acre or kg/yr/km2] • concentration [mg/liter]

13. River Ecosystems(3):river chemistry • mass balance in a channel segment • dominated by input and output • retention decreases with increasing velocity and decreasing biological activity • longitudinally, incremental uptake/deposition leads to an assimilative capacity for consumable inputs • by a combination of assimilation and dilution abnormally high inputs can be processed longitudinally • nutrient cycling becomes nutrient spiraling Spiraling length Sb Sw

14. River Ecosystems(3):river chemistry Mass/Volume Mass flux (load)/ water flux (Q) • dissolved material load • constituents reflect hydrologic source and history of material contacts • concentrations highly variable across landscape (spatial) as well as over time [C] = L / Q [C] = a Q b-1 Concentration Mass balance For a Completely Mixed Flow reactor VdC/dt = QCin – QCout +/- VrC

15. L b >1 b=1 b< 1 Q b<< 1 • material transport in rivers: load • flow Þ transport • three categories of material [load] • dissolved (chemistry) • suspended • bed All forms of load are highly variable over time (flow effects) L = a Q b Where a and b are constants • Point Source (PS) and non-Point Source (NPS) loading • PS loads relatively constant (b<<1, concentration strongly subject to dilution) • NPS loads usually increases with increasing runoff: note options

16. Typical non-point source Load (quantity/time) hysteresis Typical point source Q

17. Typical non-point source Concentration (quantity/vol) Typical point source Q

18. Sol. Reactive Phosphate (ppm) 1 1 2 3 2 Nitrate+Nitrite (ppm) 3

22. Primary productivity of Aquatic ecosystems Monod’s model • A basic model for enzyme mediated reaction rates. Common used to describe the relationship between concentrations of a limiting input and the resulting rate of photosynthesis. • growth or uptake rate = (S * Max) / (S+K) • S=input concentration; Max= maximum rate; K=1/2 saturation constant

23. Primary productivity of Aquatic ecosystems Max photosynthetic rate 1/2 max concentration of limiting input [S] K value Monod’s model • A basic model for enzyme mediated reaction rates. Common used to describe the relationship between concentrations of a limiting input and the resulting rate of photosynthesis. • growth or uptake rate = (S * Max) / (S+K) • S=input concentration; Max= maximum rate; K=1/2 saturation constant

24. Monod’s model Max photosynthetic rate 1/2 max concentration of limiting input [S] K value • Ecological implications: • photosynthesis responds in a non-linear fashion to changes in all essential inputs

25. Monod’s model Max photosynthetic rate 1/2 max concentration of limiting input [S] K value • Ecological implications: • photosynthesis responds in a non-linear fashion to changes in all essential inputs • small changes in rare inputs can induce large responses, • but large changes in common inputs can have relatively small consequences

26. Physiological richness

27. Liebig’s Law of the minimum • yield or growth of an organisms is determined by the abundance of that substance which, in relationship to the needs of the organism, is least abundant in the environment [i.e.,at a minimum]

28. Liebig’s Law of the minimum

29. Liebig’s Law of the minimum • there is always some input which is least abundant and limits primary production

30. limiting factors may change over time and across space • co-limitations are important

31. [Si] : [TP] <160

32. RCC: does it work? Riparian condition allocthonous DETRITAL L decomposers [terrestrial POOL Bacteria & fungi ] leaves, wood, DOC Veloc grazers shredders autochthonous L 1 collector-gathers [algae+ macrophytes] filter-feeders Nutrients L 0 L Light invert 2 predators invertivorous fish /birds L 3 L 4 piscivorous fish L piscivorous birds /mammals 5

34. INSECT PREDATORS? FISH? Invert. biomass Grazer biomass FLOODS? DISEASE? Algal Biomass Algal Biomass POLLUTION? DROUGHTS? Nutrients Nutrients Top-down community controls and high disturbance regimes can obscure simple responses to nutrient inputs

35. 400000 400000 300000 300000 200000 200000 100000 100000 50000 50000 40000 40000 30000 30000 20000 20000 10000 10000 5000 4000 5000 4000 3000 3000 2000 2000 1000 1000 500 400 500 400 300 200 300 200 4 5 6 7 8 9 10 20 30 40 5 6 7 8 9 10 20 30 40 Periphyton Invertebrates Drift Bedrock Biomass [mg d.w. m-2] SRP [ug/l-1] SRP [ug/l -1]

36. Figure 3. Hypothetical (A) and fitted (B) path diagram illustrating results of CSA of the effects of hydrologic disturbance on benthic algal and primary consumer biomass in Knobs and glacial drift streams. Rectangles are observed exogenous and endogenous variables, ovals are unmeasured, latent variables, and small circles are error variances. Numbers give the magnitude of direct effects, and numbers in italics are squared multiple correlations. Bold indicates significant effects at p < 0.05 based on bootstrapped error estimates (n = 133).

38. Oxygen consumed Biological Oxyen Demand BOD ppm Oxygen ppm time