How people are changing Earth's systems

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Paving covers soil with a surface that rain cannot soak into, so the rain runs off into streams (USGS, EPA). Ari traces paving through Earth's systems. Which pair changes first, then next?

   • The geosphere (land surface), then the hydrosphere (stream flow)
   • The hydrosphere (water) alone, since the land surface stays the same
   • The biosphere (plants), then the atmosphere (air), with no change in water
   • The atmosphere (air), then the geosphere (rock), since rain falls from the air
2. 2.

   Clearing a forest removes plants that store carbon, and bare soil can vent carbon (NASA). Bo follows a cleared forest. Which two systems change, and how?

   • The hydrosphere loses plants, and the geosphere gains CO₂
   • The biosphere alone changes, since plants are the thing that gets removed
   • The atmosphere loses plants, and the biosphere gains CO₂
   • The biosphere loses plants, and the atmosphere gains CO₂
3. 3.

   A dam slows river water, so sediment settles in the reservoir (USGS). Kira traces a dam through three systems. Which statement matches the card?

   • Hydrosphere: water speeds up. Geosphere: sediment is carried farther along
   • Hydrosphere: water slows. Geosphere: sediment piles up in the reservoir
   • Hydrosphere changes alone; the sediment stays in motion past the dam
   • Atmosphere: water slows. Geosphere: sediment is lost from the river

4. Read this first

   Where rain goes as land is paved (USGS, from FISRWG 1998)

   Ground cover	Evapotranspiration	Runoff	Shallow infiltration	Deep infiltration
   Natural ground cover	40%	10%	25%	25%
   10–20% impervious	38%	20%	21%	21%
   35–50% impervious	35%	30%	20%	15%
   75–100% impervious	30%	55%	10%	5%

5. 4.

   At 75–100% impervious cover, what share of rain runs off, and what share soaks in deep, by Jun's reading?

   • 30% runs off, and 5% soaks in deep
   • 55% runs off, and 5% soaks in deep
   • 5% runs off, and 55% soaks in deep
   • 10% runs off, and 25% soaks in deep
6. 5.

   How does deep infiltration change from natural ground to 75–100% impervious cover, by Luz's reading?

   • It rises from 5% to 25% of the rain
   • It falls from 25% to 5% of the rain
   • It falls by 5 percentage points of the rain
   • It falls from 25% to 10% of the rain
7. 6.

   At 35–50% impervious cover, what share of rain soaks into the ground (shallow plus deep), by Milo's math?

   • 65%, the share that does not soak in
   • 20%, the shallow share alone
   • 30%, the runoff share
   • 35%
8. 7.

   Storm sewers concentrate runoff, which gains speed and erosional power. Storm sewers collect runoff, and EPA says it gains speed and erosional power. What does that do to a stream bank downstream, by Noah's reading?

   • No change, since the stream receives the same rain as before
   • Less erosion, because pavement soaks up the extra water
   • More erosion, because faster water carries more and cuts more
   • Less erosion, because the water drops its sediment sooner
9. 8.

   Runoff carries oil, dirt, chemicals and fertilizers. Roads, lots and rooftops keep rain from soaking in. Why does runoff from a city block carry oil and fertilizer into a stream, by Pia's reading?

   • Pavement makes oil and fertilizer when rain falls on it
   • Water that cannot soak in runs across surfaces and picks up what lies on them
   • Rain soaks into the soil and brings oil and fertilizer up to the stream
   • Streams make their own oil and fertilizer from the sediment they carry

10. Card (EPA)

    a city block makes more than 5 times the runoff of a same-size woodland. Model data: the woodland gives 200 gallons.

11. 9.

    A woodland gives 200 gallons of runoff in a storm (model data). A same-size city block gives more than 5 times that. At least how much, by Ren's math?

    • About 40 gallons
    • About 205 gallons
    • More than 1,000 gallons
    • About 100,000 gallons

12. Card (NOAA)

    The ocean absorbs CO₂ from the air. Surface pH has fallen about 0.1. A lower pH means a more acidic solution.

13. 10.

    Surface ocean pH has fallen about 0.1 as the ocean takes up CO₂. What does that mean, and which systems exchange the CO₂, by Zee's reading?

    • The seawater is more acidic, and CO₂ moves from the hydrosphere to the atmosphere
    • The seawater is unchanged, since CO₂ stays in the air above the ocean
    • The seawater is less acidic, and CO₂ moves from the atmosphere to the hydrosphere
    • The seawater is more acidic, and CO₂ moves from the atmosphere to the hydrosphere