APES 7.4 - Atmospheric CO2 and Particulates

Natural Sources of Air Pollutants

  • Overview of various natural sources contributing to atmospheric air pollutants, specifically carbon dioxide and particulate matter.

Lightning Strikes

  • Natural source of nitrogen oxides (NOx).

    • Energy converts nitrogen (N2) into nitrogen oxides (NOx) and oxygen (O2).

Forest Fires

  • Major contributor to multiple air pollutants:

    • Carbon monoxide (CO)

    • Carbon dioxide (CO2)

    • Particulate matter (PM)

    • Nitrogen oxides (NOx)

    • Water vapor (not a regulated gas, but a greenhouse gas)

Plant Emissions

  • Plants, especially coniferous trees, emit volatile organic compounds (VOCs).

    • Terpenes are a common type of VOC from plants.

    • Example: Strong odor of pine in forests despite lacking specific pollutants.

Volcanoes

  • Major source of sulfur dioxide and particulate matter.

    • Release of ash and other pollutants during eruptions.

    • Also release carbon monoxide and nitrogen oxides (NOx).

Sources of Carbon Dioxide and Particulate Matter

Respiration

  • Biological source of carbon dioxide:

    • All living beings, including plants, emit CO2 during cellular respiration.

    • Important to note: not a major contributor compared to other sources.

Natural Particulate Sources

  • Salt from the ocean

  • Pollen from plants

  • Ash and soot from forest fires

  • Dust from soil carried by wind

    • Can create haze, distinct from photochemical smog.

Aerobic Decomposition

  • Breakdown of organic matter in oxygen-rich environments.

    • Example: Decomposition of fallen trees leads to CO2 release.

Anaerobic Decomposition

  • Breakdown of organic matter in low or no oxygen.

    • Environment: Bogs, marshes, and wetlands.

    • Produces methane (CH4) instead of carbon dioxide due to lack of oxygen.

Particulate Matter Overview

Definition

  • Particulate matter (PM): solid or liquid particles suspended in the air.

    • Term interchangeable with "particles" or "particulates."

Sizes of Particulate Matter

PM10

  • Particles 10 micrometers or smaller.

    • Includes dust and pollen.

    • Too small to be filtered out by respiratory system, potentially causing health issues.

PM2.5

  • Particles 2.5 micrometers or smaller.

    • More concerning due to deep lung penetration.

    • Linked to chronic bronchitis, heart problems, and increased risk of lung cancer.

  • Experiment measuring particulate matter around road construction.

    • Students use Vaseline-coated petri dishes at varying distances from the construction site and an existing road.

  • Control Group:

    • Dishes placed near the existing road, not under construction.

  • Dependent Variable:

    • Amount of particulate matter collected on the Vaseline in the petri dishes.

  • Measurement Approach:

    • Compare the PM amounts from dishes at distances of 50, 100, and 200 yards from both the construction site and the existing road.