Chapter 10 Soil Erosion, Leaching, and Pollution 237 Copyright Goodheart-Willcox Co., Inc. Wind and water are primary eroding agents of soil. Once soil structure is dis- rupted, individual particles can be dislodged by wind and water. In almost all cases, soil that is dislodged and moved to a new location is less productive than it was in its natural state. Wind Erosion Wind erosion is the removal and displace- ment of surface soil by the force of wind. Wind erosion creates dust and dust storms that move soil particles from their native fi elds to new loca- tions. Wind erosion occurs most frequently in arid regions. Water Erosion Water erosion is the movement and dis- placement of soil by the force of water. Erosion by water is more common on most land than wind erosion. Water is one of the most powerful forces on Earth. Water is capable of washing and moving tons of soil from fi elds into rivers and streams in a single rain event. Soil Infi ltration and Percolation To understand water erosion, we need to understand soil infi ltration and percola- tion, Figure 10-5. Infi ltration and percolation rates are important factors in water erosion. The Dust Bowl Major wind erosion occurred in the 1930s in the Great Plains during the Dust Bowl. History Connection The 1920s were years of abundant rainfall in the Great Plains. The farmers took advantage of the weather and an increased demand for wheat and plowed thousands of additional acres of native prairie grasses to create more fields for planting. When the onset of severe drought began in 1931, soil conditions became very dry and the loosened soil was blown away in some of the most intense dust storms in history. Dust traveled from the Oklahoma Panhandle to the sidewalks of Boston and the steps of the United States Capitol in Washington, D.C. Consider This 1. How much of an impact did the dusty conditions have on the health of the population? 2. Were there any illnesses attributed to the dusty conditions in the Great Plains? Everett Historical Society/Shutterstock.com Amanita Silvicora/Shutterstock.com Figure 10-5. Soil erosion begins when precipitation rates exceed infiltration rates and water pools before it begins to flow downslope. Soil not saturated Percolation Soil still saturated Pool of water Infiltration from the surface pools nts of soil. Once soil structure is dis- g a sp w n d r d w n r er ol o nts of soil. Once soil structure is dis ge w n d r d w n r o 310 Natural Resources Systems Copyright Goodheart-Willcox Co., Inc. Each form of water plays important roles in environmental processes. A frost heavee, for exam-- ple, occurs when water-saturated soil or other hard substratum freezes and expands, Figure 13-3. These heaves can be destructive to roadways and other manmade structures but they are impor- tant in nature to allow water to move more easily through the ground. The blankets of snow that often cover much of the northern hemisphere in winter add water to sources above and below the ground. Locations of WaterW Water is found in the atmosphere, at Earth’s surface, and below the ground. It is also found in all living beings, Figure 13-44. Each location plays an important role in the hydrologic cycle.yc Atmospheric Water Atmospheric water is water vapor that enters the air around us through processes such as transpiration evaporation. Atmospheric water plays a large role in determining the weather. The level of humidity, for example, is an approximation of the water vapor in the air. Atmospheric water also accumu- lates in clouds and condenses into liquid water, which is released in some form of precipitation. Howard Perlman, Jack Cook, Woods Hole Oceanographic Institution, Adam Nieman USGS, Igor ShiklomanovvS Figure 13-4. The largest sphere represents all of Earth’s water (332,500,000 mi3 km3]), the second sphere represents Earth’s liquid water (2,551,100 mi3 [10,633,450 km3]), and the smallest sphere represents the source of most of the water (22,339 mi3 [93,113 km3]) used by living beings each day. Freshwater 2.5% Other saline water 0.9% Oceans 96.5% Total global water water and other Freshwater Surface/other freshwater 1.2% Ground-- water 30.1% GlaciersFigure and ice caps 68.7% Atmospheree 3.0% Living beingsgsieb 0.26% Rivers 0.49% Swamps,s,pS marshesm 2.6%%2 Soil moisturem 3.8% Lakes 20.9% Ground ice and permafrost 69.0%.69 wlkellar/Shutterstock.com Figure 13-3. Frost heaves are common in the winter when freezing and thawing occur regularly. Here, a roadside has broken away because of the freezing water. E ach f orm o f water pla ys important roles in v ironmenta l processes. A frost heave , f or exam , occurs w h en water-saturate d soi l or ot h er h ar dand b stratum freezes and expands, Fi gure 13-3 . e se h eaves can b e d estructive to roadways an d h er manma de structures b ut th e y are impor- n t in nature to allow water to move more easil y ough the g round. The blankets of snow that en cover much o f the northern hemisphere in n ter aalso l so a dd water to sourc es ab ove an d bel ow g roun d. ocatio t t t ti i ons of ater W ater is found in the atmosphere, at Earth’s r face, and below the g round. It is also found a ll livin g bein gs, Figure 13- . Ea ch locsnowmelt ati on ay s an important role in the hy drolo gic cle. r vapor t h at enters t h e air aroun d us th rou gh aand n d evapor ation. Atmosp heric water pl a ys a a ther. The level of humidit y, for example, is an or in the air. Atmospheric water also accumu- o liq uid water, which is released in some form e rlman, UUSGS SGS Jack C ook, Woods Hole Ocea nographic In stitution, Adam Nieman USGS , Igor hiklomano 500,000 mi 3 [[1,386,000,000 1,386,000,000 km 3 ]), the second SSurface urface water and other frfreshwater eshwater Freshwater S urface /other f reshwater 1.2 % Ground- d- w a ter 30. 1% Glaciers and ice caps 68.7% A tmosp her 3.0% Liv i ng n 0.26% Rivers 0.49% wam arshes .6 S oil oisture 3 .8 % Lakes 20. 9% Ground ice and permafro st 0% 350 Natural Resources Systems Copyright Goodheart-Willcox Co., Inc. Sewage is wastewater that contains human and/or animal feces and urine. Domestic gray water is water from sinks, showers, washing machines, and dishwashers. Gray water and water from storm drainage typically fl ows into the same system used to control sewage, Figure 14-17. In more developed countries, sewage disposal systems are elaborate, underground plumbing operations designed to carry contaminated wastewa- ter to treatment facilities. The treatment facilities are used to remove effl uent (suspended solids) and adjust the pH of the wastewater before returning the water to natural waterways. Wastewater must be treated and cleaned to prevent the spread of disease to protect our environment. The removal of organic and inorganic waste helps maintain oxygen levels in the water as well. Treated wastewater and recycled gray water may be used in industrial cooling or production, water turfgrass in recreational areas, and to irrigate cropland in some instances.to Overflow during heavy precipitation or No overflow during dry weather Treated wastewater Wastewater treatment plant Storm water runoff Sanitary sewers Sanitary Storm water Combined Overflow during heavy precipitation or snowmelt No storm water discharge during dry weather Treated wastewater Wastewater treatment plant Storm water runoff Sanitary sewers Sanitary Storm water Combined (city) Sabelskaya/Shutterstock.com (water 14-17. New sewer systems separate storm water from wastewater to reduce the risk of contamination.Macrovector/Shutterstock.comtreatment) 634 Natural Resources Systems Copyright Goodheart-Willcox Co., Inc. Chinese PrivetLigustrum Chinese privet ( sinense), Figure 24-28, is even more noxious than kudzu. Chinese privet is a woody shrub that quickly outcompetes native plant species. It has several com- petitive advantages over other plants. It grows quickly and pro- duces abundant, viable seeds. It can also reproduce vegetatively via root suckers. Chinese privet currently covers more than 3.2 million acres of forested land in the South. It was originally introduced to the United States as an ornamental shrub in 1852. Chinese Tallow Chinese tallow (Triadica sebifera) is an invasive tree of the southern United States. Chinese tallow is native to Asia. In Asia, it is cultivated for its oil, which is used in biodiesel production. Chinese tallow trees grow to about 20′ (6.1 m) tall, so they are relatively short trees. The leaves and fl owers produce a toxin that make them distasteful to insects, birds, and other herbivores. The trees reproduce via abundant seeds that are spread by birds and moving water. Chinese tallow trees have a deep, substantial taproot that allows the tree to withstand periods of drought. Cogon Grass Cogon grass (Imperata cylindrica), Figure 24-29 , is a perennial grass that is native to Asia. It was introduced to Alabama in 1912 in packing materials from Japan. Cogon grass grows from 2′ (0.6 m) to 10′ (3.0 m) tall. It produces a white, fl uffy seed head in the late spring and early summer. Its rhizomatic roots grow as deep as 4′ (1.2 m) into the soil. Chinese privet produces a fruit that is sweet smelling but toxic to humans. Did You Know? wasanajai/Shutterstock.com Figure 24-28. Chinese privet is the most n oxious invasive weed in the South. Figure 24-29. Cogon grass is a perennial grass that can grow up to 10′ tall. Doikanoi/Shutterstock.com Chapter 6 Habitat Destruction 143 Copyright Goodheart-Willcox Co., Inc. Management of Invasive Species Invasive species are almost impossible to eradicate but there are means to limit their spread. In the United States, laws concerning fi rewood transport, ship-ballast water elimination, animal release, and even restrictions on the use of various landscape plants have been established to help prevent the introduc- tion and spread of invasive species. Agricultural Destruction Human-caused destruction can be on a small or a large scale, ranging from plowing an acre of prairie land to the slash-and-burn farming techniques used to clear acres of tropical forests. Crop production exposes the land to ero- sion, depletes natural soil fertility, and introduces fertilizers and pesticides to the soil and surrounding environment. It reduces the native fl ora, which often forces the native fauna to seek new habitats. In addition, agricultural runoff is one of the greatest sources of water pollution. In South America, thousands of acres of rain forest are destroyed each year to create pastures for livestock or fi elds for crop production. The exposed rain forest soil becomes vulnerable to erosion due to rain and wind. Oftentimes, exposure to the elements causes the soil to lose its ability to support any type of plant growth, Figure 6-7A. The disturbed ecological communities in the rain forest would take thousands of years to return to their original natural state. Additional Human Activities Urbanization, mining, logging, and recreational activities all contribute to the destruction of habitats, Figure 6-7B. As we clear the land of its natural inhabitants, we affect the local ecosystems. The degree of that impact depends on how the species involved can handle change and how great the level of destruction. What other invasive species have been introduced to Australia? How have these species harmed Australia’s ecosystems? Thinking Critically “Destroying rain forest for economic gain is like burning a Renaissance painting to cook a meal.”Wilson, —E.O. American Biologist, Naturalist, and Author Photo by Susan Berescik Figure 6-7. A—Commonly used in South America and Asia, slash-and-burn habitat destruction allows for the quick clearing of land for livestock grazing or crop production. B—Mining operations are a cause of major habitat destruction. Open pit mining, such as this mine in Montana, destroys the landscape, destructs habitats, and may pollute nearby waterways. Maksimilian/Shutterstock.com A B Illustrations have been designed to clearly and simply communicate specific topics Thinking Critically questions develop higher-order thinking skills, problem-solving skills, personal skills, and workplace skills History Connection features show students how we can learn from our mistakes and introduce the people who were behind the initial fight to preserve our natural areas Did You Know? features point out interesting and helpful facts about natural resources and conservation