Natural Dust Flashcards
What is Loess?
Dry powdery wind-blown soil
Where is the loess plateau located? How big is it?
Within Ningxia, Shanxi, and Shaanxi. 640,000 km2. In the northwest region of China. Next to Tibetan plateau.
What river surrounds the Loess Plateau?
Yellow River
Why is Loess plateau the way it is?
Centuries of overuse and overgrazing led to high erosion rates and widespread poverty. Also due to monsoons.
What causes desertification?
- Overgrazing by sheep,goat and livestock
- cutting down trees or other vegetation
What methods have been used on the Loess Plateau?
- Warping dams to create rich fertile fields in the valley
- terrace side of ravines
-fish scale
Why is it important people be involved in rehabilitating the land?
- Land use rights
- Lift people out of poverty, people get paid
- shared responsibility, stewardship
- personal achievement and pride
China has how many percent of world population?
22%
How much of China’s land is arable? ( able to be agriculture )
7%
what was the project initiated in Loess Plateau? What was it for? What does it teach?
Loess Plateau Watershed rehabilitation project. It was to mitigate desertification. It teaches people to keep goats in pens and not let them roam freely to erode soft silty soil found in plateau.
Has loess plateau watershed rehabilitation project worked?
Yes, some trees and grass have turned green.
- 5% of plateau total rea is restored ( 35000 sq km)
- Massive silt loads to Yellow River is reduced to 1%
where does loess come from?
- River deposits
- mountains
- river carrying sediments
- North-western winds blow silt
Where are the 3 alluvial fans?
- Central Asia Orogenic Belt
- Qilian mountains
- North China Craton
What is monsoon’s effect on Loess?
- Monsoon is the source
- picks up silt on the way
- rainful helps with dry and wet deposition of dust
why is so much dust formed here?
- highest known uplift rates in the world in the Himalayas
- rapid river incision, thus sediment production
- unstable slopes
- glaciation
- erosion from freeze-thaw fracturing
What mineral is loess made of?
- Quartz
- Feldspar
- Mica
- Carbonate
how thick is loess deposit?
Up to 500m
Physical charactersitics of Loess
- susceptible to erosion and landslide
- low density, not very heavy
- soft
- high porosity
- collapses when wet
How big is dust from Loess?
5 - 15 micrometers
Difference between respirable, thoracic and inhalable
Respirable : particles can get to deepest part of lungs
Thoracic: deposited in upper airways
Inhalable: Breathe it back out
What type of particle is loess silt?
Respirable
what is exposure limit for crystalline silica?
0.1 mg/m3
How much was measurment of crystalline silica in loess plateau?
Outdoor: 4.2
Outdoor: 20
Windy season: 8.25-22
Whats the illness associates with loess plateau?
- Silicosis (desert silicosis)
What is Silicosis?
- Happens when crystalline silica embeds onto alveolar sacs
shortens of breath, cough, fatigue
Other health hazard from natural dust- Al Eskan disease
Al Eskan disease
- lung exposure to fine sand dust first diagnosed in 1990 Gulf war.
- immunosuppression that can be aggravated by infections
Other health hazards from natural dust- Valley Fever
- Develops as mold with long filaments that break off into airborne spores when it rains
- swept into air during winds, monsoons, farming
- infection caused by inhalation of spores after soil disruption
- C immitis is otherwise dormant
- tiredness, fever, cough, headaches
