Analysis of Water Chemistry

Urban Stream Restoration ProjectBy:

AG-Pentian

Outline

• Water Chemistry Background

• Chemistry in Urban Streams

• Methods

• 2003 Results

• Comparison to 2002

• Conclusions

Outline

• Water Chemistry Background• Chemistry in Urban Streams

• Methods

• 2003 Results

• Comparison to 2002

• Conclusions

Temperature

• Most aquatic organisms are cold-blooded and have an ideal temperature range, specific to the organism:

• Diatoms 15-25 degrees C

• Green algae 25-35 degrees C

• Blue greens 30-40 degrees C

• Salmonids – cold water fish

Temperature, continued

• Affects development of invertebrates, metabolism of organisms

• Affects dissolved oxygen (warm water holds less oxygen)

• Warm water makes some substances more toxic (cyanide, phenol, xylene, zinc) and, if combined with low DO, they become even more toxic

Dissolved Oxygen

• Oxygen that is dissolved in water• DO increases with cooler water and mixing of

water through riffles, storms, wind• Nutrient loading can lead to algal blooms which

result in decreased DO• 4-5 ppm DO is the minimum that will support

large, diverse fish populations. Ideal DO is 9 ppm. Below 3 ppm, all fish die.

Dissolved Oxygen, continued

• Dissolved oxygen can also be expressed as % saturation

• 80-124% = excellent

• 60-79% = ok

• < 60% = poor

Conductivity

• Measures the ability of water to carry an electric current

• Measures the ions such as Na+, Cl- in the water

• Differences in conductivity are usually due to the concentration of charged ions in solution (and ionic composition, temp.)

• Reported as microsiemens per cm

pH

• pH measures the degree of acidity or alkalinity of the water (each number is a 10-fold difference)

• 0-6 = acid; 7 = neutral; 8-14 = base• Ideal for fish = 6.5 –8.2• Ideal for algae = 7.5 – 8.4• Acid waters make toxic chemicals (Al, Pb, Hg)

more toxic than normal, and alter trophic structure (few plants, algae)

Turbidity

• Measures the cloudiness of the water

• Turbidity caused by plankton, chemicals, silt, etc.

• Most common causes of excess turbidity are plankton and soil erosion (due to logging, mining, farming, construction)

Turbidity, continued

• Excess Turbidity can be a problem:• Light can’t penetrate through the water –

photosynthesis may be reduced or even stop – algae can die

• Turbidity can clog gills of fish and shellfish –can be fatal

• Fish cannot see to find food, but can hide better from predators

Phosphorus (Reactive)

• Is necessary for plant and animal growth

• Natural source = phosphate-containing rocks

• Anthropogenic source = fertilizer and pesticide runoff from farming

• Can stimulate algal growth/bloom

Nitrates

• Formed by the process of nitrification (addition of O2 to NH3 by bacteria)

• Used by plants and algae• Is mildly toxic, fatal at high doses• Large amounts (leaking sewer pipes, fertilizer

runoff, etc.) can lead to algal blooms, which can alter community structure, trophic interactions and DO regimes)

• Below 90 mg/L seems to have no effect on warm water fish, but cold water fish are sensitive

Alkalinity

• A measure of the substances in water that can neutralize acid and resist changes in pH

• Natural source = rocks

• Ideal water for fish and aquatic organisms has a total alkalinity of 100-120 mg/L

• Groundwater has higher alkalinity than surface water

Hardness

• The amount of Calcium and Magnesium in the water (the two minerals mostly responsible)

• Natural source = rocks

• Limestone = hard water, granite = not hard water

Hardness, continued

• Soft water can be a problem: in soft water, heavy metals are more poisonous, some chemicals are more toxic, drinking soft water over long periods can increase chance of heart attack

• 0 – 60 = soft water• 61-120 = moderately hard water• 121-180 = hard water• 181+ = very hard water• Hardness and alkalinity are related

Outline

• Water Chemistry Background

• Chemistry in Urban Streams• Methods

• 2003 Results

• Comparison to 2002

• Conclusions

Physical Effects of Urbanization Related to Water Chemistry

• Riparian Vegetation Removal

• Decreased Groundwater Recharge

• Heat Island Effect

• Increased Surface Runoff / Impervious Surfaces

• Leaky Storm-water / Sewage Pipes

• Point Source Pollution

Trends in Water Chemistry

• Temperature increases

• Nitrate increases

• Phosphorus increases

• Conductivity increases (Increased ion concentration)

• O2 demand increases

Outline

• Water Chemistry Background

• Chemistry in Urban Streams

• Methods• 2003 Results

• Comparison to 2002

• Conclusions

Field Measurements

• Dissolved Oxygen• Temperature• Conductivity• pH

Water Collection For Laboratory Analysis

• Grab Samples

• Three replicates (from multiple samples)

• Measured within 24 hours (few exceptions)

Picture Source: http://www.ci.gresham.or.us/ departments/des/stormwater/water_quality.htm

Laboratory Analysis

• Nitrate• Reactive

Phosphorus• Alkalinity• Hardness• Turbidity

Outline

• Chemistry in Urban Streams

• Water Chemistry Measurements and Theory

• Methods

• 2003 Results• Comparison to 2002

• Conclusions

Field Measurements 2003Temperature (oC)

0

5

10

15

20

1 2 3

Dissolved Oxygen (mg/L)

0

5

10

15

1 2 3

Conductivity (us)

0

200

400

600

800

1 2 3

pH

5

5.5

6

6.5

7

7.5

1 2 3

SAL PB

Turbidity

• All values for 2003 <5 jtu

• For 2002, all but one sampling date <5 jtu

• The one date for 2002 >5 was during a storm event

Reactive Phosphorus 2003

0

0.05

0.1

0.15

0.2

0.25

1 2 3Sampling Date

mg/

L

PB SAL

Nitrate 2003

0

0.5

1

1.5

2

2.5

1 2 3Sampling Date

mg/

L

**

PB SAL

Alkalinity 2003

0

5

10

15

20

25

30

35

40

45

1 2 3Sampling Date

mg

CaC

O3/

L

***

PB SAL

Hardness 2003

0

2

4

6

8

10

12

1 2 3

Sampling Date

g.d

.h.

*

* *

PB SAL

Outline

• Chemistry in Urban Streams

• Water Chemistry Measurements and Theory

• Methods

• 2003 Results

• Comparison to 2002• Conclusions

Field Measurement PBDissolved Oxygen (mg/L)

0

5

10

15

1 2 3

Conductivity (us)

0

50

100

150

1 2 3

pH

5

5.56

6.57

7.5

1 2 3

Temperature (oC)

0

5

10

15

20

1 2 3

2002 2003

Field Measurement For SALDissolved Oxygen (mg/L)

02468101214

1 2 3

Temperature (oC)

0

5

10

15

20

1 2 3

Conductivity (us)

0

200

400

600

800

1 2 3

pH

6.6

6.7

6.8

6.9

7

7.1

7.2

1 2 3

2002 2003

Paint BranchReactive Phosphorus (mg/L)

0

0.1

0.2

0.3

0.4

0.5

1 2 3

Nitrate (mg/L)

0

0.5

1

1.5

2

2.5

1 2 3

Alkalinity (mg CaCO3/L)

0

5

10

15

20

1 2 3

Hardness (g.d.h.)

0

0.5

1

1.5

2

1 2 3

2002 2003

Stewart April LaneReactive Phosphorus (mg/L)

0

0.2

0.4

0.6

0.8

1

1.2

1 2 3

Nitrate (mg/L)

0

0.5

1

1.5

2

2.5

1 2 3

Alkalinity (mg CaCO3/L)

0

10

20

30

40

50

60

1 2 3

Hardness (g.d.h.)

0246

81012

1 2 3

2002 2003

Outline

• Chemistry in Urban Streams

• Water Chemistry Measurements and Theory

• Methods

• 2003 Results

• Comparison to 2002

• Conclusions

Between Site Differences

• Land use – increased runoff cause increased input of particular constituents

• Natural site variation – Substrate type

Between Years

• Increased snow caused more runoff increased use of road-salt

• Drought (temperature, DO)

“. . . Rivers and the inhabitants of the watery element were made for wise men to contemplate, and fools to pass by without consideration, . . . for you may note, that the waters are Nature’s storehouse, in which she locks up her wonders.”

Izaak Walton

(from Ward, 1992)