Tutor profile: Devin B.
Subject: Environmental Science
What is a saline soil? List 2 natural causes and 2 anthropogenic causes of soil salinity. Do you think that soil salinity would occur more in the Western or Eastern U.S. and why?
A saline soil refers to a non-sodic (does not contain sodium) soil that contains enough soluble salt to adversely affect the growth of most crop plants. Saline soils affect the plants themselves and reduce the availability of water in the soil through osmotic potential. When there is a higher level of salt concentration outside of the plant (in the soil), the water from inside the plant will be sucked out through osmosis, resulting in toxic water loss. Remember, in osmosis, water molecules travel from an area of low solute concentration to an area of high solute concentration in order to create an equilibrium. Two natural causes of soil salinity are weathering of parent rock materials and coastal salt spray. Two man-made causes of soil salinity are irrigation and exploitation of coastal groundwater aquifers (resulting in seawater intrusion). Soil salinity occurs more in the Western U.S. because there are higher levels of irrigation for croplands. Additionally, evaporation rates are higher because there is less water (humidity) in the air. This evaporation leaves behind a lot of salts in the soil. Soil salinity is a major issue, particularly in areas like Central Valley, CA where irrigation is essential for agricultural farms. The major problem with soil salinity is that it is very difficult to fix. The main way to solve salty soil is to irrigate large amounts of high-quality water in order to drain the salts away, however, this is both wasteful and difficult to accomplish.
What is the difference between osmosis and diffusion?
Osmosis specifically refers to the diffusion of water across a membrane, whereas diffusion refers to the movement of any type of molecule from one place to another. In osmosis, water will move from an area of low solute concentration to an area of high solute concentration until the solute concentration is equal on both sides of the cell. In diffusion, the molecules go from an area of high concentration to an area of low concentration until there is equilibrium.
Select the best word to fill in the blank. My dog _______ a bone yesterday. a. have b. has c. had
The correct answer is "c. had". Since the verb is reflecting a singular noun (dog), you would not use "a. have". While answer "b" is close, it would still not be the best choice as the word "yesterday" implies a past action. Therefore, answer "c" is the best option for this sentence.
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