Module IV: CZ in the Classroom

https://waterdata.usgs.gov/monitoring-location/01583580/

US Geological Survey gaging stations

Baisman

Run

W Br Herring RUn

Towson U

Cromwell Valley Park

~0.8” in 1 hr

~1.5” in 3–4 hr

~0.8” in 1 hr

~0.25” more that happened 12 hours later

Specific Conductance & Chloride in the Chesapeake Bay Watershed

A Case Study

HS-ESS2-2 Earth’s Systems

Analyze geoscience data to make the claim that one change to Earth's surface can create feedbacks that cause changes to other Earth systems

Activity Outline

1. Introducing the issue - Elevated specific conductance levels in the Chesapeake Bay watershed

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• Researching potential causes

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• Researching Cotd. - Integrating Urban CZ Work

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• Conclusions & Ranking

Specific Conductance - Why Does it Matter?

• Specific conductance is an “…indirect measure of the collective concentration of dissolved ions in solution” (USGS)
• Can indicate presence of chloride, nitrate, & sulfate - either human caused or naturally occurring

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• Elevated specific conductance (and by extension elevated concentrations of these major ions) is associated with:
• Decline in species abundance and diversity of freshwater ecosystems
• Lower quality of water used for drinking or irrigation

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• In urban systems in particular, conductivity + chloride levels are highly correlated - conductivity can act as a little bit of a proxy here

https://tigerweb.towson.edu/moore/chloride_map_12062019.html

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Chloride & specific conductance (SC) highly correlated for sites & regions

Discrete Cl vs SC

High correlation means that high-frequency SC can be used to calculate chloride concentrations

even at (silicate) sites without discrete [Cl] data

Plumtree Run – Bel Air, MD

Moore, Fanelli, & Sekellick (2020) Env. Science & Tech. 54: 778-789

Chloride & specific conductance (SC) highly correlated for sites & regions

Discrete Cl vs SC

High correlation means that high-frequency SC can be used to calculate chloride concentrations

even at (silicate) sites without discrete [Cl] data

Plumtree Run – Bel Air, MD

Mid-Atlantic region (piecewise

regression)

R² = 0.9795

N = 2401

Moore, Fanelli, & Sekellick (2020) Env. Science & Tech. 54: 778-789

How is increased chloride relevant to water quality?

https://www.wsscwater.com/water-filtration

https://en.wikipedia.org/wiki/Mayfly

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• Drinking water quality
• Increased formation of disinfection byproducts
• Increased corrosivity

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• Watershed, including ecosystem health
• Negative effects on freshwater organisms, particularly macroinvertebrates
• Impacts nitrogen & phosphorus cycling
• Changes soil characteristics, e.g., pH
• In some places, observed increases in trace metal concentrations

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Aquatic life: Mayfly abundance vs specific conductance

Clements & Kotalik (2016) Freshwater Science 35: 126–138

Naturally high conductivity

Naturally low conductivity

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Mayfly abundance

Courtesy of Joel Moore & USGS

Elevated Specific Conductance & Chloride Levels in the Chesapeake Bay Watershed

In front of you are maps of the Chesapeake Bay watershed that display various traits:

• Precipitation
• Land cover
• Impervious Surfaces
• Physiographic Region

+ SC & Chloride

Look over the maps. Are there any patterns you might be able to see? What hypotheses can you make that might explain the elevated chloride & specific conductance levels we see in the Chesapeake Bay watershed?

Research: 10-15 minutes

Take some time to research what you’ve noticed from the data we’ve provided. Can you find evidence to support your initial thoughts?

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Search Terms to Consider:

• Chesapeake Bay watershed
• Specific Conductance
• Chloride
• Tributary
• Impervious Surface
• Land Cover
• Bedrock Chemistry

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Bringing Out Papers

If you’re stuck, head to the front & grab the paper we’ve included for you! It should help you on your way.

Conclusions

Drawing on the papers & resources you found on your own, list & rank two (2) or more things that impact elevated Cl and SC levels in the Chesapeake Bay watershed.

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Your rankings should be based on whatever your group feels is the most important

eg: most affected by climate change, most impact on ecosystems, most important to human activity

Then, present your rankings to the larger group!

Chloride increases from south to north

https://tigerweb.towson.edu/moore/chloride_map_12062019.html

Southeast

Mid-Atlantic

New England

Moore et al (2020) Environmental Science & Technology

Chloride increases from south to north & with impervious within region

https://tigerweb.towson.edu/moore/chloride_map_12062019.html

Southeast

Mid-Atlantic

New England

Moore et al (2020) Environmental Science & Technology

Impervious cover (and associated) salting drive big increases

Preliminary data (not for distribution) from a collaborative study with USGS led by Rosemary Fanelli

Modeling specific conductance for every reach in Chesapeake Bay watershed

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4 periods from 2001 – 2016

Impervious cover (and associated) salting drive big increases

Disclaimer: This information is preliminary and is subject to revision. It is being provided to meet the need for timely best science. The information is provided on the condition that neither the U.S. Geological Survey nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information

Modeling specific conductance for every reach in Chesapeake Bay watershed

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4 periods from 2001 – 2016

Preliminary data (not for distribution) from a collaborative study with USGS led by Rosemary Fanelli

Impervious cover (and associated) salting drive big increases

Preliminary data (not for distribution) from a collaborative study with USGS led by Rosemary Fanelli

Modeling specific conductance for every reach in Chesapeake Bay watershed

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4 periods from 2001 – 2016

Long-term increases in chloride: Example from Baltimore region

1. Cl (& Na) concentrations have doubled to tripled since 1980s even with most tributary watersheds having less than 2–3 % impervious surface cover

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• Concentrations have increased even faster in more urban tributaries

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Beaver Dam Run, Cockeysville

Gunpowder Falls, Hoffmanville (upstream of Prettyboy)

Long-term Cl increases: Example from Baltimore water supply tributaries

Gunpowder

Falls

Western Run

Beaver

Dam

1980s

2010s

Beaver Dam Run

note some high conc.

not shown

Gunpowder

Western

Run

<2–3% impervious

~13% impervious

Monthly chloride data from Baltimore City DPW

Monthly chloride data from Baltimore City DPW

Long-term Cl increases: Example from Baltimore water supply tributaries

Mean annual chloride (mg/L)

Flow-normalized

Kyle Hurley

(now USGS)

Gunpowder

Falls at Glencoe

Beaver Dam Run

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30% of Cl flux from <10% of watershed

Hurley theis, WRTDS modeling

Monthly chloride data from Baltimore City DPW

Hurley thesis, WRTDS modeling

Monthly chloride data from Baltimore City DPW

Summary

1. Increasing (& elevated) chloride concentrations have negative effects on freshwater ecosystems and drinking water quality
2. Long-term: Chloride concentrations are increasing in streams, lakes, and groundwater across with US, particularly in areas using deicing salts

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• Short-term: Chloride concentrations are often substantially higher in winter due to deicing salt use with variations ideally characterized by high-frequency data (minutes to hours)

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• Stormwater: Best practices for managing stormwater can increase chloride concentrations in groundwater and subsequently streams & lakes (though perhaps with shifted timing)

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• Research gaps include
1. determining chloride patterns and effects at (eco)regional scale
2. figuring out residence time and how long before reduced application rates would have effect

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• Problem is increasingly on people’s radar and things are beginning to move in right direction

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Summary

• Increasing (& elevated) chloride concentrations have negative effects on freshwater ecosystems and drinking water quality
• Long-term: Chloride concentrations are increasing in streams, lakes, and groundwater across with US, particularly in areas using deicing salts

​

• Short-term: Chloride concentrations are often substantially higher in winter due to deicing salt use with variations ideally characterized by high-frequency data (minutes to hours)

​

• Stormwater: Best practices for managing stormwater can increase chloride concentrations in groundwater and subsequently streams & lakes (though perhaps with shifted timing)

​

• Research gaps include
• determining chloride patterns and effects at (eco)regional scale
• figuring out residence time and how long before reduced application rates would have effect

​

• Problem is increasingly on people’s radar and things are beginning to move in right direction

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Lunch - until 1:30

Draw the CZ pt 2

It’s time to draw the CZ again! Knowing what you know now in comparison to yesterday, redo your drawing of the Critical Zone.

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Once you’re done, find a place in the room to hang it up.

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Lee et al., 2023

Reflection

Reflections on Classroom Connections

• How has your understanding of the CZ changed since starting this workshop?
• What was most challenging about the Sierra activity? What was most rewarding? Why?
• Who is someone in your life you’re excited to connect with over CZ science in the future?
• How did you feel looking at your initial drawing of the CZ? How did it feel to edit it based on new information?
• What is something that you’re going to take with you from this workshop back to your classroom?

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Curriculum Project

Over the next two hours (& beyond), work to create a piece of curriculum on the CZ that you can integrate into your lessons

Brainstorming

1. Write down 10 things we’ve covered in this workshop you might incorporate in your classroom (things you can expand on, concepts, etc)

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• Share top 3 with a partner

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• Pick one to write your curricular project on!

Over the next hour(ish)

1. Start formulating an outline for your curricular project

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• Prepare a poster that summarizes your project

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We will have a poster session afterwards to share your ideas!*

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*We want your ideas, not your perfectly articulated plans! Outlines, vague ideas, general concepts, etc. are all welcome & encouraged

Poster Session

Want to continue developing this curriculum?

• Mini grants ($500) available for curriculum writing
• Curriculum will be placed on BCZN website for widespread use, and then posted on SERC website once BCZN grant is complete
• To be considered for mini grant:
• Present curricular project to Jorden & Lily
• Respond to Lily’s email in the coming days re: mini grants
• Direct questions to Jorden or Lily

Wrap Up and Evaluations

Certificates

Thank You!