Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Living soil system / Atmospheric dust deposition and loess as soil parent material
Atmospheric dust deposition and loess as soil parent material
Wind-blown mineral dust from deserts and glacial outwash settles on land and ocean, adding fine parent material (loess), base cations and phosphorus to soils and iron to the sea.
Boundary: where this process starts
Starts with: Wind lifts silt and clay from arid, glacial-outwash and dry-lake surfaces
Boundary: where it ends
Ends after: Persistent deposition builds silt-rich, carbonate-rich loess that weathers into fertile soil; Dust iron reaches high-nutrient low-chlorophyll ocean regions and relieves iron limitation of phytoplankton
Line thickness = size of impact (1 to 5)% on a line = chance a fork takes that branch📄 = pieces of evidence on a stepNegative effectLoops backHypothesisResource used up (arrow into the step)Resource used, not used upResource made or released (arrow out of the step)
What am I looking at? The concepts on every map
- Participant
- Someone or something that takes part in a process or influences it: a plant, a microbe, a river, a machine, a force. Participants are the rows of a map.
- Resource
- Something a step uses or uses up: water, oxygen, sunlight, a tool. Each step has an arrow down to the resources it uses.
- Step
- One thing that happens in a process. Every step has at least one participant and carries evidence.
- Decision fork
- A step where the process can go several ways. Every outcome is labeled with a percentage, and the percentages add up to 100%. It is not limited to yes or no.
- Loop
- A line that carries the process back to an earlier step. We record whether it reinforces or balances, how strong it is (weak, moderate, strong), and its gain (0 to 1): the share of the effect that returns on each pass.
- Size of impact
- Every line says how much the earlier step affects the next one (1 to 5), in which direction (+, -, 0), and why. Thicker lines mean bigger impact.
- Evidence
- The support for a claim: a source and what it shows. Every step, line, change and vote needs it. Click any step or line to read its evidence.
- Boundary
- Where a process starts and where it ends. Every process, and every subprocess, has a start and an end.
- Subprocess
- A step that is itself a whole process, with its own boundary, steps and lines. Click a step marked ↘ to open it. Subprocesses nest as deep as the evidence goes.
- Description
- A plain-language summary of what a process is and what it covers.
- Hypothesis
- A proposed new connection between two parts of the map that nobody has linked. It carries a prediction, a way to test it, and a count of papers on each topic and on both. It is an unverified idea until someone tests it.
Every step, with its evidence
The same information as the map, as a list you can search and share. Click a participant or resource to see everywhere it appears.
Wind lifts silt and clay from arid, glacial-outwash and dry-lake surfaces
Evidence (1) · added by Cinder
- Kok et al. (2021) Atmospheric Chemistry and Physics 21:8169-8193: North Africa and Asia supply most global dust emission, roughly 1,000-3,000 Tg per year. (confidence 0.7)
Dust travels days to weeks and settles by gravity and rain washout
Evidence (1) · added by Cinder
- Jickells et al. (2005) Science 308:67-71, Global iron connections between desert dust, ocean biogeochemistry and climate: Atmospheric transport carries dust over ocean basins before dry and wet deposition. (confidence 0.85)
⑂ Where the dust lands
Evidence (1) · added by Cinder
- Jickells et al. (2005) Science 308:67-71: Model estimates place deposition to the ocean at roughly a quarter to a third of total dust deposition and the rest on land; shares are model dependent (estimate 70/30). (confidence 0.55)
Dust adds phosphorus, calcium and fine particles to downwind soils (Saharan dust supplies the Amazon with about 22,000 t P per year)
Evidence (1) · added by Cinder
- Yu et al. (2015) Geophysical Research Letters 42:1984-1991, The fertilizing role of African dust in the Amazon rainforest: About 28 Tg of Saharan dust per year reaches the Amazon basin, carrying roughly 22 Gg of phosphorus, comparable to the P lost by leaching and runoff. (confidence 0.8)
Dust iron reaches high-nutrient low-chlorophyll ocean regions and relieves iron limitation of phytoplankton
Evidence (1) · added by Cinder
- Martin (1990) Paleoceanography 5:1-13, Glacial-interglacial CO2 change: the iron hypothesis; Jickells et al. 2005: Iron supply from dust controls productivity in the Southern Ocean, equatorial and subarctic Pacific. (confidence 0.8)
Persistent deposition builds silt-rich, carbonate-rich loess that weathers into fertile soil
Evidence (1) · added by Cinder
- Pye (1995) Quaternary Science Reviews 14:653-667: Loess is a silt-dominated, often calcareous sediment; Chinese Loess Plateau deposits reach 200-300 m. (confidence 0.7)