Physics, Chemistry, and Biology in Ponds and Lakes

Ponds and Lakes Dominated by Heterotrophic Processes Example. A well mixed lake with V = 5x10 8 L is fed by a stream flowing at Q=2.4x10 7 L/d that contains 8mg/L DO and has L =10mg/L. Waste from a small municipality (L =95mg/L, DO = 0 mg/l) enters the lake at 4.8 x 10 6 L/d. k d, k r, and DO* in the lake are 0.10 d 1, 0.05 d 1, and 11.2 mg/l, respectively. Assuming that the lake is at steady state: a) Determine L and DO in the lake. b) Compute the rates (kg/d) at which advection, reaeration, and biological reaction, each acting alone, increase or decrease DO and L in the lake.

Q 1 (stream), L 1, DO 1 Q 2 (waste), L 2, DO 2 V, k d L in lake Q 3, L 3, DO 3 DO in lake, k r Q 1 = 2.4 x 10 7 L/d Q 3 = Q 1 + Q 2 = 2.88 x 10 7 L/d DO 1 = 8 mg/l DO 3 =? L 1 = 10 mg/l L 3 =? Q 2 = 4.8 x 10 6 L/d DO 2 = 0 mg/l L 2 = 95 mg/l k r = 0.05 d 1 k d = 0.10 d 1 DO* = 11.2 mg/l

Q 1 (stream), L 1, DO 1 Q 2 (waste), L 2, DO 2 V, k d L in lake Q 3, L 3, DO 3 DO in lake, k r MB on L: 0 = QL 1 1+ QL 2 2 QL 3 3 kvl d in lake L mg L mg = + d L d L 7 6 0 2.4x10 10 4.8x10 95 L 2.88 10 ( 0.10 d )( 5 10 L) d L x x L L 3 = L in lake = 8.83 mg/l 7 1 8 3 3

MB on DO: Q 1 (stream), L 1, DO 1 Q 2 (waste), L 2, DO 2 V, k d L in lake Q 3, L 3, DO 3 DO in lake, k r d dt ( DO ) = ( DO ) + ( DO ) ( DO ) ( ) + ( DO* DO ) V Q Q Q k L V k V in lake 1 1 2 2 3 3 d in lake r in lake ( ) ( ) ( ) ( ) ( ) 0 = Q DO + Q DO Q DO k L V + k DO* DO V 1 1 2 2 3 3 d 3 r 3 L mg L mg L = + d L d L d mg mg + L L DO 3 = DO in lake = 0.57 mg/l ( ) 7 6 7 0 2.4x10 8 4.8x10 0 2.88x10 DO3 1 8 1 8 ( 0.1 d ) 8.83 ( 5x10 L) ( 0.05 d ) 11.2 DO3 ( 5x10 L)

Q 1 (stream), L 1, DO 1 Q 2 (waste), L 2, DO 2 V, k d L in lake Q 3, L 3, DO 3 DO in lake, k r Advective outflow of biochemical oxygen demand: (2.88 x 10 7 L/d)(8.83 mg/l) (10 6 kg/mg) = 254 kg/d Rate of L utilization (i.e., the rate of DO utilization by biochemical reactions): r L V = k d (L in lake ) V = (0.10 d 1 ) (8.83 mg/l) (5 x 10 8 L) = 4.42 x 10 8 mg/d = 442 kg/d

240 Stream (a) Lake 442 Bioactivity 254 Outlet (b) 192 Stream 266 Reaeration Lake 442 Bioactivity 16 Outlet 456 Waste 0 Waste Mass Balance Terms for L (kg/d) Mass Balance Terms for DO (kg/d)

Cladocerans

Copepods Cyclopoid Calanoid nauplii

Limiting Nutrients for Algal Growth and Lake Productivity: Nitrogen, Phosphorus & Carbon Nutrient Source Cycling Nitrogen [Atmosphere], Biological Geologic Phosphorus Geologic Physical, Chemical Carbon Atmosphere Chemical, Biological Redfield Ratio C: N : P P limited N limited 106 : 16: 1 N:P >20 N:P < 10

Carbon: rarely limiting due to ready availability from the atmosphere Nitrogen: can be limiting especially at very high phosphorus loading rates Phosphorus: most common limiting nutrient and best predictor of algal biomass Colimitation: very common for both nitrogen and phosphorus in combination to be limiting in short term (3-5 day) bioassays

Chlorophyll(µg L -1 ) Phosphorus vs. Phytoplankton Biomass 1000 100 10 1 y = 0.08x 1.5 r 2 = 0.91 0.1 1 10 100 1000 Total Phosphorus (µg L -1 ) Jones and Bachmann (1976)

Common Threats to Lake and Stream Water Quality Point Sources: sewage and industrial effluent Non-Point Sources: fertilizers, animal wastes, erosion, failing septic systems, Canada geese Point sources have for the most part been controlled A key area for future research in limnology and lake management is the development of methods for quantifying and controlling non-point source nutrients

CAFOs = Factory Farms

The Impact of Temperature on Water Density 1.000 Density (grams/cm 3 ) 0.999 0.998 Max. Density @ 4 C 0.997 0 5 10 15 20 25 Temperature (C )

Summer Stratification 0 5 Epilimnion Depth (m) 10 15 Metalimnion 20 25 Hypolimnion 0 5 10 15 20 25 Temperature (C )

0 10 20 Depth (m) 30 40 50 60 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Time of Year 8 10 12 14 16 18 20 Temperature ( C)

Temperate Lakes Deep = usually Dimictic Shallow = often Polymictic

Thermal Stratification in a Dimictic Lake 0 Summer Stratification 0 Fall Mixing 5 5 Depth (m) 10 15 Depth (m) 10 15 20 20 25 0 5 10 15 20 25 Temperature (C ) 25 0 5 10 15 20 25 Temperature (C ) Winter Inverse Stratification 0 0 Spring Mixing 5 5 Depth (m) 10 15 Depth (m) 10 15 20 20 25 0 5 10 15 20 25 Temperature (C ) 25 0 5 10 15 20 25 Temperature (C )

A Eutrophic Dimictic Lake During the Summer 0 Temperature 0 Light 5 5 Depth (m) 10 15 Depth (m) 10 15 20 20 25 25 0 Dissolved Oxygen 0 Nutrients 5 5 Depth (m) 10 15 Depth (m) 10 15 20 20 25 25

Eutrophication and Nuisance algal blooms

Chlorophyll vs. Water Clarity 8 Secchi depth (m) 6 4 2 0 0 10 20 30 40 Chlorophyll a (µg L 1 )

0 10 Depth (m) 20 30 40 50 60 0.00 0.20 0.40 0.60 0.80 1.00 Time of Year 2 4 6 8 10 Chlorophyll concentration (µg/l)

7 6 Vol. Wt. Chlorophyll Conc. (µg/l) 13 12 11 10 9 8 7 6 Lake Washington Temperature Chlorophyll 5 4 3 2 1 0 0.2 0.4 0.6 0.8 1 0 Time of Year Vol. Wt. Temperaure ( C)

Aquatic foodweb top consumers planktivores zooplankton phytoplankton

Fish Zooplankton Phytoplankton Clear Lake Peruvian Upwelling

The phytoplankton-zooplankton interrelationship appears to be particularly dependent on the species composition of the biota; hence, if the phytoplankton is composed primarily of species edible [and of nutritional value] for zooplankton, one may find a relatively low phytoplankton standing crop R.A. Vollenweider (1976) Mem. Ist. Ital. Idrobiol. 33: 53-83.

Hypereutrophy and N limitation Anoxic hypolimnion (bottom layer) Denitrification (NO 3 converted to N 2 ) Reduced conditions in sediments (Fe 3+ Fe 2+ ) Supply of NO 3 and PO 4 3-

Cyanobacteria Competitive Advantages Can fix atmospheric nitrogen Buoyancy regulation Luxury P uptake (polyphosphate crystals) Poor food quality and edibility to zooplankton Competitive Disadvantages Slow growers relative to other phytoplankton

"On May 2, 1878, George Francis of Adelaide, Australia, published the first scholarly description of the potentially lethal effects produced by cyanobacteria... in a letter to Nature... Symptoms--stupor and unconsciousness, falling and remaining quiet, as if asleep, unless touched, when convulsions come on, with head and neck drawn back by rigid spasm, which subsides before death. Time--sheep, from one to six or eight hours; horses, eight to twenty-four hours; dogs, four to five hours; pigs, three or four hours."

From the website for CellTech, the company harvesting and selling Super Blue Green Algae. 1. Super Blue Green Algae is over 60% high quality (complete) protein 2. and is the richest source of chlorophyll known to man. 3. It is a (vegetable) source of vitamin B-12, and in fact contains more B-12 than any other vegetable! 4. Super Blue Green Algae is 100% vegetarian, 100% natural and 100% wildgrown. 5. It is enzyme active for super absorption by your body and, it contains over 60 minerals and trace minerals. 6. Are there any medically proven health benefits? Super Blue Green is a food, not a drug or medicine. Therefore, we cannot promote it as having proven health consequences.

Mean depth 32 m Max depth 61 m HRT = 2.4 yr -1 Lake Washington Story

Case Study: Lake Washington Dissolved P Inputs (metric tons yr. -1 ) 125 100 75 50 25 0 Sewage Effluent Watershed Loading 1965 1970 1975 1980 1985 1990 Year From: W.T. Edmondson (1994) Lake & Reservoir Management 10: 75-84.

Change in Lake Washington phytoplankton composition and biomass Phyto. Bioviol. (mm 3 L -1 ) 3 2 1 Cyanobacteria Other Phytoplankton 0 1965 1970 1975 1980 1985 1990 Year From: W.T. Edmondson (1994) Lake & Reservoir Management 10: 75-84.

Change in Lake Washington nutrient concentrations, and phytoplankton biomass after waste water diversion 125 Percent of 1964 Value 100 75 50 25 Inorganic Carbon Nitrate Phosphate Phytoplankton 0 1965 1970 1975 Year From: W.T. Edmondson (1991) The Uses of Ecology.

Secchi (m) 0 2 4 6 Daphnia Trophic Equilibrium 0 5 10 15 20 Daphnia L -1 8 Secchi Depth 10 1965 1970 1975 1980 1985 1990 Year

10 Lake Washington seasonal phytoplankton succession Diatoms Biomass (µg Chla/l) 8 6 4 2 Cryptos Greens Cyanos Others 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Time of Year