Unit 4 polluted soil and its remediation sol220

Unit 4 polluted soil and its remediation sol220

1. Polluted Soil and remediation By- Dr. Kamini Roy Associate Professor, Agricultural Chemistry and soil science, Lovely Professional University, Phagwara (First ICAR Accredited University) By Dr. Kamini Roy

2. Soil pollution It is the the buildup of contaminants, toxic compounds, radioactive materials, salts, chemicals disease and cancer-causing agents above the permissible limit. The most common soil pollutants are hydrocarbons, heavy metals (cadmium, lead, chromium, copper, zinc, mercury and arsenic), herbicides, pesticides, oils Productive soils are necessary for agriculture to supply the world with sufficient food. By Dr. Kamini Roy

3. POLLUTED SOILS: “Soil pollution” refers to the presence of a chemical or substance out of place and/ or present at a higher than normal concentration that has adverse effects on any non-targeted organism (FAO, 2015). Although the majority of pollutants have anthropogenic origins, some contaminants can occur naturally in soils as components of minerals and can be toxic at high concentrations. Soil pollution often cannot be directly assessed or visually perceived, making it a hidden danger. By Dr. Kamini Roy

4. Soil pollution” refers to the presence of a chemical or substance out of place and/ or present at a higher than normal concentration that has adverse effects on any non-targeted organism . A. True B. False By Dr. Kamini Roy

5. Sources of soil pollution A. Agrochemicals 1. Pesticide 2. Insecticides 3. Herbicides 4. Fungicides 5. Fertilizers B. Industrial wastes 1. Effluent 2. Dust and other solid wastes 3. Radioactive waste 4. Heavy metals 5. Acid precipitation By Dr. Kamini Roy

6. C. Urban wastes 1. Municipal solid wastes 2. Municipal sewage 3. Vehicular exhaust D. Rural wastes 1. Home wastes 2. Litter 3. Livestock wastes 4. Plant residues 5. Sediment By Dr. Kamini Roy

7. Pesticide pollution Pesticides include insecticides, fungicides, nematicides , rodenticide and herbicide Their potential as a pollutant depends on their bio-degradability and toxicity to animals and human beings. Pesticide that can persist in soils for a long time affect the food chain by the process called biological magnification , meaning accumulation and subsequent concentration in the food chain. They may cause severe damage to non target animals By Dr. Kamini Roy

8. Pesticides include insecticides, fungicides, nematicides, rodenticide and herbicide A. True B. False By Dr. Kamini Roy

9. Soil pollution due to excessive use of fertilizers Indiscriminate use of fertilizers Soil nutrients are important for plant growth and development. Plants obtain carbon, hydrogen and oxygen from air and water. But other necessary nutrients like nitrogen, phosphorus, potassium, calcium, magnesium, sulfur and more must be obtained from the soil. Farmers generally use fertilizers to correct soil deficiencies. By Dr. Kamini Roy

10. Effects of chemical fertilizers i . Chemical fertilizers are generally used far in excess of the requirements of the crop. The unutilized fertilizers cause soil pollution. ii. Toxic concentrations of nitrogen fertilizers cause characteristic symptoms of nitrite or nitrate toxicity in plants, particularly in the leaves. Nitrogenous fertilizers generally cause deficiency of potassium, increased carbohydrate storage and reduced proteins, alteration in amino acid balance and consequently change in the quality of proteins. iii. Ammonium fertilizers produce ammonia around the roots that may escape the soil and cause ammonia injury to plants. By Dr. Kamini Roy

11. Ammonium fertlizers if used over extended periods produce acids in the soil and increase soil acidity. Excessive potash in the soil decreases ascorbic acid and carotene in the plants. Phosphatic fertilizer in excessive use cause deficiency Zn in plants by interfering with their uptake. Phosphorus induced Zn deficiency Excessive lime prevents the release of Co, Ni, Mn and Zn from the soil and their uptake by plants is reduced causing their deficiency symptoms. By Dr. Kamini Roy

12. Ammonium fertlizers if used over extended periods produce acids in the soil and increase soil acidity. A. True B. False By Dr. Kamini Roy

13. Effects of industrial effluents i . Various inorganic and organic substances are present in the industrial effluents. These substances mostly remain tied up in the soil and are not readily available to plants. However, they affect various soil characteristics. ii. Effluents affect soil pH, exchangeable base status etc. of the soil and thus indirectly affect the plants iii. The pH of the soil is disturbed making soil either acidic or alkaline. iv. Various inorganic and organic chemicals are accumulated in the soil up to levels toxic to plants. v. In highly polluted soils, plants absorb and accumulate toxic substances (bioaccumulation). These substances may or may not produce direct injury symptoms in plants By Dr. Kamini Roy

14. Industries effluents are the source of heavy metal pollution in soils, Depending on the industry, specific heavy metals are added with discharge in water Many small to medium scale industries operating in peri -urban residential areas of cities are disposing their contaminated effluents directly in sewage system. Studies have documented that direct disposal of effluents to land and water bodies has potential to contaminate surface, ground waters as well as soils and crops grown on these soils with heavy metals which will have bearing on human health. By Dr. Kamini Roy

15. Nitrate pollution in ground water is mainly contributed by nitrogenous fertilizers, industrial effluents. Being an anion, NO 3 is not adsorbed by the negatively charged soil surfaces and is easily transported through soil profiles into ground water. Heavy rain or irrigation after nitrogen application can carry nitrogen deep in to soil to drainage waters, sandy soils are particularly susceptible to leaching Rise in concentration of nitrate in ground water has been observed in a number of countries globally and is cause of concern to health authorities. Higher concentration of nitrate in a groundwater well used for drinking water causes a health problem in infant called methemoglobinemia ( bluebaby syndrome) By Dr. Kamini Roy

16. Nitrate pollution in ground water is mainly contributed by nitrogenous fertilizers, industrial effluents A. True B. False By Dr. Kamini Roy

17. Effects of Soil Pollution on crop production • Reduced soil fertility • Reduced nitrogen fixation • Increased erodibility • Larger loss of soil and nutrients • Deposition of silt in tanks and reservoirs • Reduced crop yield • Imbalance in soil fauna and flora By Dr. Kamini Roy

18. Prevention of soil pollution Excavation : It is removal of top polluted layer of the soils by mechanical devices to expose uncontaminated sub soil. It is followed by disposal of the soils to land fill sites Precautions associated with the excavation and transport of polluted soils need to be taken. This is a rapid method of managing polluted sites which has been widely employed in the past but it just relocates the problem and hence is not a remedial treatment. With land space becoming costly, this strategy is becoming less acceptable to industry, regulatory bodies and the public. By Dr. Kamini Roy

19. Excavation By Dr. Kamini Roy

20. Other methods Addition of various amendments like gypsum, organic matter, zeolites, lime, phosphorus Maintaining pH Controlling metal interactions By Dr. Kamini Roy

21. Excavation : It is removal of top polluted layer of the soils by mechanical devices to expose uncontaminated sub soil. A. True B. False By Dr. Kamini Roy

22. Zeolites are micro porous crystalline solids which contain silicon, aluminium . They contain linked cages or cavities which are of the right size to allow small molecules or heavy metal atoms to enter. They are natural or synthetic E.g. MOR, mordenite -type FAU, faujasite -type zeolite By Dr. Kamini Roy

23. Use of Organic matter : Bonding of organic matter with metals fix the metals and leaving lesser metal immediately available for plants. CaCO 3 : Its application fixes heavy elements or reduces availability by changing soil pH. Using organic chelates to enhance phytoextraction like EDTA or DTPA By Dr. Kamini Roy

24. Oxides of Mn and Fe : It reduces toxicity of heavy metals. By-products of industrial processes such as berginite and steel are available at affordable cost. Vitrification : In this technology an electric current is used to melt the soil at a temperature up to 2000 C. The melted soil cools to form a chemically stable, leach resistant, glass like solid mass. It encases and entrap inorganic pollutants. However, this procedure destroys the soil, thereby limiting future site use. By Dr. Kamini Roy

25. Solidification : It involves the use of resistant material which gets mixed with soil and then soil allowed to form a solid product after some time. any materials have been used in solidification technology including cement, fly ash, bitumen, and polythene. The resulting product is not a soil but can often be used as a building or construction material. By Dr. Kamini Roy

26. Nanoremediation: Using nano -sized reactive agents to degrade or immobilize contaminants is termed nanoremediation . The nanomaterials then degrade organic contaminants through redox reactions or adsorb to and immobilize metals such as lead or arsenic . Nanomaterials are highly reactive because of their high surface area per unit mass, and due to this reactivity nanomaterials may react with target contaminants at a faster rate than would larger particles. By Dr. Kamini Roy

27. Phytoremediation It is a new approach that uses specially selected metal accumulators plants to remediate soil contaminated with heavy metals. It is safe and cheap technology to implement sustainable agriculture Selected plants absorb heavy metals from roots and translocate them to shoots. Heavy metals are then removed by harvesting shoots and then ashing E.g. Thlaspi caerulescens has been used successfully to decontimate cadmium polluted soils. By Dr. Kamini Roy

28. Phytoremediation is a new approach that uses specially selected metal accumulators plants to remediate soil contaminated with heavy metals. A. True B. False By Dr. Kamini Roy

29. Phytoremediation By Dr. Kamini Roy

30. Bioremediation These are biological methods for clean up of contaminated soils. It involves establishing appropriate micro organisms to grow and carry out the metabolic activities to detoxify the contaminants. Different types of bacteria, fungi and other micro organisms are used for treating polluted soils e.g. Pseudomonas pudita , Pleurotus tuberegium (DDT, PCB’s) By Dr. Kamini Roy

31. Eroded Soil and its reclamation By Dr. Kamini Roy

32. Eroded soils Soil erosion is defined as the detachment and transportation of soil mass from one place to another through the action of wind, water in motion or by the beating action of rain drops Erosion extensively occurs in poorly aggregated soils (low humus) and in a higher percentage of silt and very fine sand. Erosion increases when soil remains bare or without vegetation. Occurence In India about 86.9% soil erosion is caused by water and 17.7% soil erosion is caused by wind. Out of the total 173.6 Mha degraded land in India, soil erosion by wind and water accounts for 144.1 Mha (Govt. of India, 1990). The surface soil is taken away by the runoff causing loss of valuable topsoil along with nutrients, both native and applied. In India about 5334 million tones (16.35 tonnes/ha/year) of soil is being eroded annually due to agriculture and associated activities and 29% of the eroded materials are permanently lost into the sea. By Dr. Kamini Roy

33. Soil erosion is defined as the detachment and transportation of soil mass from one place to another through the action of wind, water in motion or by the beating action of rain drops A. True B. False By Dr. Kamini Roy

34. Types of erosion a) Natural or geologic erosion ranges from very little in undisturbed lands to extensive in steep arid lands. Geological erosion takes place, as a result of the action of water, wind, gravity and glaciers and it takes place, at such slow rates that the loss of soil is compensated for the formation of new soil under natural weathering processes. It is sometimes referred to as normal erosion. b) Accelerated erosion caused by the disturbances of people (cutting forests, cultivating lands, constructing roads and buildings etc.) and is increasing as the population increases. In this erosion, the removal of soil takes place at a much faster rate than that of soil formation. It is also referred to as abnormal erosion. By Dr. Kamini Roy

35. Causes of Water Erosion Water erosion is due to the dispersive action, and transporting power of water. Water erosion of soil starts when raindrops strike bare soil peds and clods, resulting the finer particles to move with the flowing water as suspended sediments. The soil along with water moves downhill, scouring channels along the way. Each subsequent rain erodes further amounts of soil until erosion has transformed the area into barren soil. Water erosion may occur due to the removal of protective plant covers by tillage operation, burning crop residues, overgrazing, overcutting forests etc. inducing loss of soil. Raindrop / Splash Erosion Rain drop splash erosion results from soil splash caused by the impact of falling rain drops. The continued impact of raindrops compacts the soil and further seals the surface-so that water cannot penetrate into the soil and as a result causing more surface run off. By Dr. Kamini Roy

36. Sheet Erosion Sheet erosion is the removal of a fairly uniform layer of surface soil by the action of rainfall and runoff water on lands having a gentle or mild slope, and results in the uniform "skimming off of the cream" of the top soil with every hard rain, In this erosion, shallow soils suffer greater reduction in productivity than deep soils. It is slow process but dangerous. Movement of soil by rain drop splash is the primary cause of sheet erosion. Rill Erosion Rill erosion is the removal of surface soil by running water, with the formation of narrow shallow channels that can be levelled or smoothed out completely by normal cultivation. Rill erosion is more apparent than sheet erosion. Rill erosion is more serious in soils having a loose shallow top soil. This type of soil erosion may he regarded as a transition stage between sheet and gully erosion. Gully Erosion Gully erosion is the removal of soil by running water, with the formation of channels that cannot be smoothed out completely by normal agricultural operation or cultivation. Gully erosion is an advanced stage of rill erosion. Unattended rills get" deepened "and widened every year and begin to attain the form of ‘gullies’. During every rain, the rain water rushes down these gullies, increasing their width, depth and length. By Dr. Kamini Roy

37. Sheet erosion is the removal of a fairly uniform layer of surface soil by the action of rainfall and runoff water on lands having a gentle or mild slope, and results in the uniform "skimming off of the cream" of the top soil with every hard rain. A. True B. False By Dr. Kamini Roy

38. Stream Channel Erosion Stream channel erosion is the scouring of material from the water channel and the cutting of banks by flowing or running water. This erosion occurs at the lower end of stream tributaries. Stream bank erodes either by runoff flowing over the side of the stream bank, or by scouring or undercutting. Scouring is influenced by the velocity and direction of flow, depth and width of the channel and soil texture. By Dr. Kamini Roy

39. Harmful Effects of Water Erosion/Constraints Water erosion causes various damages to the lands as follows: Loss of top fertile soil. The surface soil lost as runoff consists of fertile soils and fresh or active organic matter. Accumulation of sand or other unproductive coarse soil materials on other productive lands. In the plains, fertile lands have been made unproductive by the deposition or accumulation of soil material brought down from the hills by streams and rivers. Silting of lakes and reservoirs. Soil erosion from the catchment areas of reservoirs results in the deposition of soil, thus reducing their storage capacity Silting of drainage and water channels. Deposition of silt in drainage ditches in natural streams and rivers reduces their depth and capacity and overflows and flooding of downstream areas increase with damage to agricultural crops and also man-made structures. Decreases water table. With the increase in runoff, the amount of water available for entering the soil is decreased. This reduces the supply of water to replenish the ground water in wells, the yield of well is reduced. Fragmentation of land. Water erosion especially gully erosion may divide the land into several valleys and ridges and thus fields become smaller and more numerous. Crop rows are shortened, movement from field to field is obstructed and a result the value of land is decreased.

40. Wind erosion Soil erosion by wind has caused an accumulation of eroded particles in loess, a type of soil which makes up some of the world's most fertile and productive regions. Soil conditions conducive to wind erosion are most commonly found in arid and semi-arid areas where rainfall is insufficient and no vegetative cover on the land. The most serious damage caused by wind erosion is the change in soil texture. Since the finer soil particles are subject to movement by wind, wind erosion gradually removes silt, clay and organic matter from the top soil, leaving the coarser soil material. Threshold Velocity Threshold velocity is the minimum wind velocity required to initiate the movement of soil particles. Threshold velocity varies with the soil conditions and nature of ground surface. By Dr. Kamini Roy

41. Soil erosion by wind has caused an accumulation of eroded particles in loess, a type of soil which makes up some of the world's most fertile and productive regions. A. True B. False By Dr. Kamini Roy

42. Wind erodes the soil in three steps. The soil particles are carried by the wind in three ways namely saltation, suspension and surface creep . Saltation: It is a process of soil movement in a series of bounces or jumps. Soil particles having sizes ranging from 0.05 to 0.5 mm generally move in this process. Saltation movement is caused by the pressure of the wind on the soil particle, and collision of a particle with other particles. The height of the jumps varies with the size and density of the soil particles, the roughness of the soil surface, and the velocity of the wind. Suspension Suspension represents the floating of small sized particles in the air stream. Movement of such fine particles in suspension is usually started by the impact of particles in saltation. Once these fine particles are picked up by the particles in saltation and enter the turbulent air layers, they can be lifted upward in the air and .they are often carried for several miles before being redeposit elsewhere. Dust particles will fall on the surface only when the wind subsides or the rain washes them down. Surface Creep Surface creep is the rolling or sliding of large soil particles along the ground surface. They are too heavy to be lifted by the wind and are moved primarily by the impact of the particles in saltation rather than by direct force of the wind. The coarse particles tend to move closer to the ground than the fine ones. By Dr. Kamini Roy

43. By Dr. Kamini Roy

44. Impact of erosion on crop yield  Erosion reduces the capacity of the soil to hold water leading to severe water stress.  Erosion contributes to losses of plant nutrients, which wash away with the soil particles. Because sub-soils generally contain fewer nutrients than top-soils, more fertilizer is needed to maintain crop yields. This, in turn, increases production costs. Moreover, the addition of fertilizer alone cannot compensate for all the nutrients lost when topsoil erodes.  Erosion reduces yields by degrading soil structure, increasing soil erodibility, surface sealing  Soil crusting is enhanced. Water infiltration is reduced, and seedlings have a harder time breaking through the soil crust. Erosion reduces productivity because it does not remove topsoil uniformly over the surface of a field. Typically, parts of an eroded field still have several inches of topsoil left; other parts may be eroded down to the subsoil. This makes it practically impossible for a farmer to manage the field properly, to apply fertilizers and chemicals uniformly and obtain uniform results. He is also unable to time his planting, since an eroded part of the field may be too wet when the rest of the field is dry and ready. By Dr. Kamini Roy

45. Erosion contributes to losses of plant nutrients, which wash away with the soil particles. Because sub-soils generally contain fewer nutrients than top-soils A. True B. False By Dr. Kamini Roy

46. Nutrient Behaviors of Eroded soils Eroded soils have a low total organic carbon content, and their humic substances, humic acid carbon, and carbohydrates are lower compared with soils that had never been cultivated (natural soils). The erosion mainly influences the active organic matter (respiration and water-soluble organic matter). Total nitrogen correlates with the carbon fractions in the eroded soils. By Dr. Kamini Roy

47. Control Measures for Eroded soils Soil conservation measures , such as contour ploughing, bunding, use of strips and terraces, can decrease erosion and slow runoff water. Mechanical measures , e.g., physical barriers such as embankments and wind breaks, or vegetation cover (and use of vegetative buffer strips) and soil husbandry are important measures to control soil erosion By Dr. Kamini Roy

48. Best Management Practices : that are used to control erosion factors of both wind and water are  Crop rotation- improves the overall efficiency of nitrogen uptake and utilization in the soil. If certain cover crops are planted in the winter, erosion and runoff is prevented when the ground thaws, and nutrients are trapped in the soil and released to the spring crops.  Contour cultivation- On gently sloping land, a special tillage practice carried out on the contour of the field can reduce the velocity of overland flow. Contour cultivation should not be carried out on steep slopes because it will merely make the erosion situation worse.  Strip cropping- It is a technique in which alternate strips of different crops are planted in the same field. There are three main types: contour strip cropping, field strip cropping, and buffer strip cropping. If the strips are planted along the contour, water damage can be minimized; in dry regions, if the strips are planted crosswise to the contour, wind damage is also minimized. The most common crop choices for strip cropping are closely sown crops such as wheat , or other forages which are alternated with strips of row crops , such as corn , soybeans , cotton , or sugar beets  Terraces - Constructing bench-like channels is otherwise known as terraces, enables water to be stored temporarily on slopes to allow sediment deposition and water infiltration. There are three types of terraces: bench terraces, contour terraces, and parallel terraces. It will control erosion in wetter areas by reducing the length of the slope. By Dr. Kamini Roy

49.  Grassed Waterways - They force storm runoff water to flow down the center of an established grass strip and can carry very large quantities of storm water across a field without erosion. Grass waterways are also used as filters to remove sediment, but may sometimes lose their effectiveness when too much sediment builds up in the waterways. To prevent this, it is important that crop residues, buffer strips, and other erosion control practices and structures be used along with grass waterways for maximum effectiveness.  Diversion structures - These are channels that are constructed across slopes that cause water to flow to a desired outlet. They are similar to grass waterways and are used most often for gully control.  Drop structures - Are small dams used to stabilize steep waterways and other channels. They can handle large amounts of runoff water and are effective where falls are less than 2.5 meters  Riparian strips - These are merely buffer strips of grass, shrubbery, plants, and other vegetation that grow on the banks of rivers and streams and areas with water conservation problems. The strips slow runoff and catch sediment. In shallow water flow, they can reduce sediment and the nutrients and herbicides attached to it by 30% to 50%.  No-till planting- This planting system prepares a seedbed 2 inches wide or less, leaving most of the surface undisturbed and still covered with crop residues. The result is a wetter, colder environment that protects the seed and soil with its insulating effect of the surface residue. By Dr. Kamini Roy

50. Acknowledge and Thanks Author is immensely thankful to all the websites and books whom I contacted to make these slides more informative and attractive By Dr. Kamini Roy

51. WE SHALL OVERCOME Stay healthy By Dr. Kamini Roy