QoW 3

Which of the following is not an example of competitive absorption of H+ and nutrients (the reason for the pH dependence of soil nutrition)?

  1. The carboxylates of clay minerals are protonated by H+ ions, reducing the amount of nutrients that can bind.

  2. The H+ ions in a lower pH environment will protonate the final oxygen of the silicate edge, reducing the amount of nutrients that can bind.

  3. A lower pH will protonate soil nutrient cations, reducing their ability to bind to particles within the soil column.

  4. The final oxygen along an oxide edge will become protonated with a lower pH, reducing the amount of nutrients that can bind to the soil particles.

Based on what we’ve previously studied with regards to weathering, soil formation, and ecology in New Hampshire and Vermont, which of these conclusions is likely incorrect with regards to their differences in soil?

  1. The depth of the overall soil profile of Vermont is likely deeper than New Hampshire.

  2. The composition of the O horizon is likely identical between the two states.

  3. There will likely be more calcium present in the A and B horizons of Vermont soil than New Hampshire.

  4. The depth of the E horizon in New Hampshire is likely deeper than Vermont.

Two students are discussing the type of weathering that dominates in a humid, tropical climate.

Student A: I think physical weathering is more dominant in humid, tropical climates. When temperatures change quickly, rocks expand and contract, which causes them to crack and break apart. In hot places, this happens often, so physical weathering must be more common.

Student B: I disagree. In humid, tropical climates, there’s constant moisture and consistent warmth. Water facilitates chemical reactions, where minerals in the rock react with water and break down. The heat speeds up these reactions, so chemical weathering should be the dominant process.

Based on their conversation, which student is correct, and why? 

  1.  Student A is correct because rapid temperature changes in humid, tropical climates lead to frequent expansion and contraction of rocks, causing physical weathering.

  2.  Student B is correct because high moisture levels and consistent heat in tropical climates accelerate chemical processes that alter the mineral structure of rocks and lead to chemical weathering.

  3.  Neither student is correct because both types of weathering are equally dominant in humid, tropical climates.

  4.  Both students are correct because both physical and chemical weathering are more dominant in cold, dry climates than humid climates.Which of the following describes how composting relates to the O horizon?

Which of the following describes how composting relates to the O horizon?

  1. Composting reduces the need for the O horizon, as inorganic fertilizers are more effective for soil health.

  2. The product of composting enhances the O horizon, which increases the amount of available nutrients for plants.

  3. Composting creates a separate layer above the O horizon.

  4. The nutrients in compost decompose too quickly, leading to the erosion of the O horizon and loss of soil fertility.

How does pollution circulate across the world through atmospheric processes?

  1. Pollution remains confined to local areas because global wind patterns do not significantly affect transport.

  2. Global pollution circulation is driven by differential heating between the equator and poles, the Coriolis effect, and temperature variation with altitude. 

  3. Pollution circulates globally in a uniform manner due to consistent temperature and wind patterns across all regions.

  4. Pollution only mixes globally over very short timescales, typically within days, without significant influence from wind or temperature differences.

What statement does NOT accurately describe the effects of climate on soil formation?

  1. Cold and dry climates often lead to soil forming that is a result of physical weathering.

  2. Chemical weathering takes place in hot and wet climates to form soil.

  3. Primary minerals are found more often in soils in cold and dry climates.

  4. Sand is more frequent than clay in soils in hot and wet regions.

If a scientist encounters a profile where minerals like iron and clay are heavily concentrated in a lower horizon, and the above horizons show signs of significant leaching and depletion, which horizon is most likely responsible for this mineral accumulation after thousands of years?

  1. O Horizon

  2. A Horizon

  3. B Horizon

  4. C Horizon

Which is incorrect?

  1. Mercury is especially dangerous because although it is a heavy metal, it can be in the form of a gas

  2. Volcanoes produce gases that contribute to pollution

  3. Wet deposition makes up for around 80% of aerosol removal 

  4. O3 (ozone) can act as a pollutant in the troposphere resulting in smog

  5. None of these are incorrect

What are the main components for the O horizon in soil? 

  1. natural materials such as leaf bits, plant fibers, and dark organic/carbon matter

  2. quartz, plagioclase and other granules of minerals from weathered bed rock 

  3. alluvial minerals that make a stark white layer

  4. organic clays such as vermiculite and kaolinite

What are the six contributing categories to soil formation?

  1. Climate, organisms, relief, parent material, time, human activity

  2. Climate, organisms, radiation, pH, time, human activity

  3. Carbon cycle, organisms, relief, pH, topography, human activity

  4. Carbon cycle, organisms, radiation, parent material, time, half-life

Which of the following statements about soil loss is NOT correct?

  1. Organic matter loss occurs primarily through wind and water erosion.

  2. Acid rain contributes to soil loss by causing nutrient depletion and aluminum toxicity.

  3. Desalinization can contribute to soil loss from over irrigation.

  4. Poisoning of the soil can occur due to PFAS in sludge and atmospheric deposition of lead (Pb) and mercury (Hg).

Soil is essential for sustaining ecosystems, with each layer serving a specific function that contributes to the health of the environment. These layers vary in composition, structure, and the role they play in supporting plant growth and the overall nutrient cycle. Considering the different layers that make up soil, which of the following statements provides the most accurate description of their composition and their roles in maintaining plant life and soil fertility?

  1. The topsoil layer, also known as the A horizon, is composed primarily of solid rock and has little impact on plant growth. Most of the nutrients and organic matter required for plants are found in the subsoil, or B horizon.

  2. The bedrock, known as the R horizon, is the main source of nutrients for plants. Over time, it weathers and breaks down into minerals, which are absorbed by plant roots through the topsoil, providing essential nutrients.

  3. The topsoil, or A horizon, is where most of the organic matter, nutrients, and microorganisms crucial for plant growth are concentrated. The subsoil, or B horizon, plays a secondary role by storing water and minerals that leach down from the topsoil, contributing to long-term plant support.

  4. The organic layer, or O horizon, lies beneath the topsoil and is primarily composed of compacted minerals and weathered rock, with minimal influence on the cycling of nutrients or the health of the ecosystem.

Given that more conjugate base molecules allow for greater availability for metals and ions to bond, how does the comparison of pH and pKa of soil affect the fertility of the soil?

  1. If pH is greater than the equilibrium constant of pKa, the soil is basic and therefore there are more conjugate base molecules (soil is more fertile)

  2. If pH is less than the equilibrium constant of pKa, the soil is basic and therefore there are less conjugate base molecules (soil is less fertile)

  3. If pH is greater than the equilibrium constant of pKa, the soil is acidic and therefore there are more conjugate base molecules (soil is less fertile)

  4. If the pH is less than the equilibrium constant of pKa, the soil is acidic and therefore there are less conjugate base molecules (soil is more fertile)

Which of the following is a major way that human activity affects soil formation and quality?

  1. Humans speed up natural soil formation processes through construction and urbanization

  2. Agricultural practices, deforestation, and industrial activities accelerate erosion and nutrient depletion, altering soil formation and quality

  3. Human activities usually have no large impact on soil formation, which is only influenced by natural processes

  4. The use of fertilizers in agriculture improves soil formation and thickens soil horizons by replenishing lost parent material

Which of the following steps is not part of the life cycle of pollutants? 

  1. Emission: When particles and pollutants are released into the atmosphere. 

  2. Transportation: When particles are picked up in the wind and are pushed in different directions.

  3. Transformation: When different pollutants collide and combine to mix together. This process is driven by UV radiation, oxidation, and/or condensation. 

  4. Dropping: When all pollutants drop out of the atmosphere. All pollutants drop out of the air through rainout processes after the same amount of time in the atmosphere.

Which soil type has a fully correct description?

  1. The Oa soil, which is part of the O horizon, is made of larger plant leaves and fragments such as pine needles and is great for agriculture.

  2. Soil in the E horizon is very mature soil that has been leached to a white color.

  3. Saprolite is a layer of soil close to rock in texture and is part of the B horizon.

  4. Andisols are a globally common type of soil made from volcanic clay that is good for agriculture.

How does the Coriolis effect impact the advection of pollutants, such as sulfur dioxide and PM2.5, in the atmosphere?

  1. It causes pollutants to concentrate at the equator

  2. It deflects pollutants away from their source in a curved path

  3. It causes pollutants to remain suspended directly above their source

  4. It has no significant impact on the movement of atmospheric pollutants