Analysis of Water Chemistry

• Urban Stream Restoration Project

• 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)

• 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 2003

• 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

• Nitrate 2003

• Alkalinity 2003

• Hardness 2003

• Outline

• Chemistry in Urban Streams

• Water Chemistry Measurements and Theory

• Methods

• 2003 Results

• Comparison to 2002

• Conclusions

• Field Measurement PB

• Field Measurement For SAL

• Paint Branch

• Stewart April Lane

• 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)

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