- Soil Of About 50 Mineral Matter And Humus Partially Decayed Organic Matter And About 50 Pore Spaces Soil Is The Unco 1 (576.7 KiB) Viewed 31 times
- Soil Of About 50 Mineral Matter And Humus Partially Decayed Organic Matter And About 50 Pore Spaces Soil Is The Unco 2 (1.33 MiB) Viewed 31 times
- Soil Of About 50 Mineral Matter And Humus Partially Decayed Organic Matter And About 50 Pore Spaces Soil Is The Unco 3 (1.45 MiB) Viewed 31 times
- Soil Of About 50 Mineral Matter And Humus Partially Decayed Organic Matter And About 50 Pore Spaces Soil Is The Unco 4 (327.24 KiB) Viewed 31 times
- Soil Of About 50 Mineral Matter And Humus Partially Decayed Organic Matter And About 50 Pore Spaces Soil Is The Unco 5 (219.03 KiB) Viewed 31 times
Thank you so much!
SOIL of about 50% mineral matter and humus (partially decayed organic matter) and about 50% pore spaces Soil is the unconsolidated material on the surface of which contain air and water. All four ingredients Earth that supports the growth of plants. Soil consists must be present to support the growth of plants.
FIGURE 5.2 | How to read a triangular graph. See text for discussion. Soil is classified based upon the relative proportions 100% sand on the right (figure 5.2a). The right side of of sand, silt, and clay-sized particles. Sand consists the triangle shows the percent silt from 0% silt at the of grains 1/16 mm−2 mm in diameter, silt consists of top of the triangle to 100% silt in the lower right corgrains 1/16 mm−1/256 mm in diameter, and clay ner of the triangle (figure 5.2 b ). The left side of the consists of grains <1/256 mm. triangle shows the percent clay from 0% clay in the A soil classification chart is a three-sided graph drawn lower left corner of the triangle to 100% clay at the on an equilateral triangle. A triangular graph allows top of the triangle (figure 5.2c). The dot in Figure you to plot three variables (sand, silt, and clay) that 5.2 d shows the location of a soil sample that is 40% sum to a constant ( 100%). The base of the triangle sand, 35% silt, and 25% clay. Note that the percents of shows the percent sand from 0% sand on the right to 38 Chapter 5 Soils and Groundwater
Fasten the lid to the remaining stack and shake the sieves side to side for about 2 minutes. Remove the lid and separate the remaining sieves. Use a funnel to pour the material in the top sieve into a graduated cylinder. Gently tap the side of the cylinder until the material achieves a level surface. Do not pack down the soil because this will reduce the volume by reducing the size of the spaces between the grains. Record the volume of sand in milliliters. Repeat for silt and clay. Add the volume of sand, silt, and clay together to get the total volume of the soil sample. Determine the percent sand, silt, and clay. The percent sand is the volume of sand divided by the total volume of soil times 100%. Repeat for silt and clay. Determine the textural classification of your soil sample by plotting the percentages of sand, silt, and clay on the "Soil Textural Classification Chart in figure 5.1." GROUNDWATER A series of sieves are used to separate a soil sample into with water. The water in the phreatic zone is called sand, silt, and clay-sized particles. A sieve is a container with a crimped wire mesh bottom such that particles smaller than the mesh spacing will fall through the mesh and those larger than the mesh spacing will remain in the container. By using a series of sieves with different mesh spacing, it is possible to separate a soil sample into sand, silt, and clay sized particles. Begin with a known volume of soil sample. Stack the sieves so that the screen with the largest openings is on top. Each sieve has progressively smaller screen openings until the bottom sieve has a solid bottom without any screen. Pour the soil sample into the top sieve and secure the lid tightly. Shake the sieves side to side for at least one minute. Remove the lid and the top sieve from the stack. All the particles in this sieve are larger than 2 mm, so are not considered to be soil particles. Set them aside. FIGURE 5.4 Pore space is the space between grains. Chapter 5 Soils and Groundwater 39
groundwater. The top of the phreatic zone is called The elevation of the water table (called hydraulic the water table. head) changes from location to location. If the elevaIf you look closely at unconsolidated material, you tion of the hydraulic head changes between two locawill notice that the grains do not fit tightly together. tions, the groundwater will tend to flow under the The spaces between the grains are called pore spaces. influence of gravity from the area where the water table is at a higher elevation into an area where the water table is at a lower elevation. The direction of porosity = volume of sediment or rock volume of pore space groundwater flow can be determined by contouring the elevation of the water table throughout an area. Groundwater flows down slope (hydraulic gradient) The volume occupied by pore spaces is called the perpendicular to the contours at any given location. porosity and is usually stated as a percent. The porosity is influenced by grain shape, arrangement, and sorting (distribution of grain sizes). A well sorted sediment where the grains are mostly the same size will have a higher porosity than a poorly sorted sediment where the smaller grains can lodge in the spaces between the larger grains, thus reducing the porosity. Well sorted sediments typically have porosities of about 50%. Typical porosities in rocks range from about 1% to about 35%. MEASURING POROSITY Slowly pour the water into the beaker until the sand is entirely saturated and the water level in the beaker just equals the level of the surface of the sediment. Record the volume of water you added (the original 100ml minus the amount of water left in the gradu- ated cylinder): The porosity of the sediment is the volume of water you added to the beaker divided by the volume of the original sediment ( 100ml ). CALCULTMG HMRAULG vation of the water table at the first well minus the eleven be the water table at the second well divid- ed by the between the first and second wells. 40 Chapter 5 Soils and Groundwater
TABLE 5.1 Typical porosity, n, and hydraulic conductivity, K, for coarse sand and silt. Groundwater velocity = porosity Hydraulic gradient × hydraulic conductivity For example, a contaminant in well A of figure 5.5 moving through a coarse sand aquifer towards well D would move at a velocity of (0.020×147ft/day)/0.35= 8.4 feet/day. CALCULATING GROUND WATER VELOCITY The groundwater velocity in feet/day is the hydraulic gradient times the hydraulic conduc- tivity divided by the porosity.
What is the classification of a soil that is 35% sand, 45% silt, and 20% clay? You found that a sandstone was capable of holding 18ml of water. Calculate the porosity of the sandstone if the volume of the sandstone is 100ml. Show your calculation, including units. Calculate the hydraulic gradient between two wells that are 1000 feet apart, given that the elevation of the water table in the first well is 980 feet and the elevation of the water table in the second well is 970 feet. Show your calculation, including units.