A soil contaminant is an element (also known as ‘heavy metals’ or inorganic contaminants, e.g. le...
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28 | DanielleS |
March 10, 2019 07:36
| about 5 years ago
BACKGROUNDER: SOIL TESTING FOR CONTAMINANTS What is a soil contaminant and where does it come from? A soil contaminant is an element (also known as ‘heavy metals’ or inorganic contaminants, e.g. lead) or a chemical (also known as ‘organics’, e.g. diesel oil) present in the soil at a level that poses health risks to plant, animal or human health. Common soil contaminants include PCBs, PAHs, petroleum products, heavy metals and pesticides. We can be exposed to contaminants through the soil through: - skin contact: dermal exposure-e.g. pesticides - inhalation: breathing in dust- e.g. asbestos, lead; and/or contaminants that vaporize from soil-e.g. benzene - ingestion: eating of dust and soil through hand-to-mouth and to a lesser extent through eating foods grown in contaminated soil as some can uptake heavy metals With exposure to any contaminant, the likelihood that health effects will occur depends on how harmful or toxic the contaminant is to humans, how much you are exposed to, and for how long and often you are exposed. Contaminants in soils can come from historical industrial activity, past and present land use, nearness to pollution sources (i.e. a major road, a coal plant) and natural disasters. Contaminants can end up in your soil through: - the air (from dust & exhaust) - water (from rain & groundwater & runoff from a nearby site) - direct deposition (from on site (e.g. Pesticide application, burning garbage, or nearby polluters). Why test the soil for contaminants? People test their soil for contaminants for a range of reasons: - To see if the soil is safe to grow food in and/or reduce risk of exposure to contaminants through existing or future farms and gardens. - To see whether contaminants may have been or are being deposited on your site through runoff (water) or air from nearby busy roads or polluting industries. - To see what the contaminants may have been left behind on the soil after a natural disaster such as flooding or fire, or a chemical spill. - To see whether remediation efforts are working. Common Soil Contaminants to be aware of: Heavy metals Heavy metals are those elements which are toxic to humans at certain concentrations, including: - arsenic - copper - lead - mercury - nickel - chromium - cadmium -zinc - aluminum -manganese -barium - molybdenum Some of them, like zinc and copper, are necessary or beneficial to living organisms in small concentrations but are toxic above a certain concentration; others, like lead, cadmium and mercury, serve no known biological function and are always toxic. Heavy metals are naturally occurring, found in rocks, soil systems and bedrock, and in some places a certain metal may be naturally present in higher concentrations (such as arsenic in New York State). The majority of heavy metal contamination arises from human activity– metal mining and smelting, agrochemical fertilizers and pesticides, sewage sludge, oil and gas operations and fossil fuel burning, improper waste disposal, and fill used in residential development. Unlike organic contaminants, heavy metals cannot be broken down, so the they keep building up in soils. But their characteristics may change so that they can be more or less easily taken up by plants or animals. **Organic Chemicals ** Organic contaminants are carbon-based, meaning they are derived or manufactured from something that was once alive, for example, oil and gasoline, which is the remains of plant and animal matter that was compressed for millions of years, then pumped out of the earth and processed. Polyaromatic Hydrocarbons (PAH’s) and other petroleum hydrocarbon contaminants, solvents like trichloroethylene (TCE), dioxins, chemical pesticides, and Polychlorinated Biphenyls (PCB’s) are a few organic contaminants of note. They can be present in soils, particularly on or near historical or present-day oil and gas industry, auto and machine repair shops, old or leaky oil tanks, busy roads or highways, landfills and dumps, beneath electrical stations and wires, and places where there were building fires or demolished buildings. Polycyclic Aromatic Hydrocarbons PAH’s are a byproduct of incomplete combustion, and are released when fossil fuels are burnt. They are common in soils along busy roads due to vehicle exhaust, and are associated with coal burning power plants, forest fires, and road sealants. Other sources of PAHs include wood burning stoves and oil spills. There are more than 15 different types of PAH’s. Some PAHs are known to be cancer-causing, or carcinogenic. They have also been associated with respiratory illnesses. In soils, PAHs are likely to stick tightly to soil and organic matter particles; though certain PAHs move through soil to contaminate underground water or volatilize into the air. Poly Chlorinated Bisphenols Though they were banned in 1979, they are still present in the environment because they are highly persistent (do not readily break down) and can leak from landfills where they have been disposed of and from products that were made before the ban. They were used broadly in the electrical and building industries, and so are common in soils beneath electrical transformers and capacitators, flooded areas, and soils where buildings have been demolished. Since they don’t really break down, and bind to fats, they end up in our water and in our fish and seafood. So it’s especially important to know if they are present in places where people fish! You can read more about each specific contaminant through the Agency for Toxic Substances and Disease Registry’s 2 page fact sheets, called Tox FAQ’s: [https://www.atsdr.cdc.gov/toxfaqs/index.asp ] |
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27 | DanielleS |
March 08, 2019 06:05
| about 5 years ago
Soils are often compacted, nutrient deficient, and can sometimes contain heavy metals and other contaminants as a result of historical industrial activity, past and present land use and nearness to pollution sources (i.e. a major road, a coal plant). We can be exposed to contaminants through soils and these can have health effects over the long term. What is a soil contaminant and where does it come from?A soil contaminant is an element (like lead) or a chemical (like diesel oil, also known as ‘organics’) present in the soil at a level that poses health risks to soil, plant, animal or human health. Contaminants can end up in your soil or on your plants through the air (dust, exhaust), water (rain, groundwater), and direct deposition (from on site or nearby polluters). **Soil contaminants include: Heavy metals (Inorganic chemicals) Heavy metals are those elements which are toxic to humans at certain concentrations, including arsenic, copper, lead, mercury, nickel, chromium, cadmium, zinc and aluminum. Some of them, like zinc and copper, are necessary or beneficial to living organisms in small concentrations but are toxic above a certain concentration; others, like lead, cadmium and mercury, serve no known biological function and are always toxic. Heavy metals are naturally occurring, found in rocks, soil systems and bedrock, and in some places a certain metal may be naturally present in higher concentrations. The majority of heavy metal contamination arises from human activity– metal mining and smelting, agrochemical fertilizers and pesticides, sewage sludge, oil and gas operations and fossil fuel burning, improper waste disposal, and fill used in residential development. Unlike organic contaminants, heavy metals cannot be broken down. (Well, except through nuclear fission!) As such, they can continue to build up in soils. But their characteristics may change so that they can be more or less easily taken up by plants or animals. Many of the practices that gardeners, especially organic gardeners, already use in their gardens- such as mulching, feeding the soil with organic matter and compost- can limit the potential for soil contaminants to be taken up in food crops. Organic Chemicals Chemical/organic contaminants are carbon-based, meaning they are derived or manufactured from something that was once alive, for example, oil and gasoline, which is the remains of plant and animal matter that was compressed for millions of years, then pumped out of the earth and processed. Polyaromatic Hydrocarbons (PAH’s) and other petroleum hydrocarbon contaminants, solvents like trichloroethylene (TCE), dioxins and Polychlorinated Biphenyls (PCB’s) are a few organic contaminants of note. They can be present in soils, particularly on or near historical or present-day auto and machine repair shops, old or leaky oil tanks, busy roads or highways, landfills and dumps, beneath electrical stations and wires, and places where there were building fires or demolished buildings. If you’re concerned you have this type of contaminant because of historical or present land use, or nearness to a busy road or auto-shop, you can get a soil test done for Total Petroleum Hydrocarbons (TPH’s), and /or Polycyclic Aromatic Hydrocarbons (PAH’s) and either avoid growing in areas of contamination, grow in raised beds, or take steps to remediate the soil (see “Earth Repair, by Leila Darwish”). Should I be concerned about soil contamination?It is likely that the soil in any urban setting will contain some level of heavy metal and organic contaminants, and long-term exposure can have health risks, particularly for children. Lead and other heavy metals in soil can enter the human body through inhalation or ingestion of dust and soil (on vegetables) and, to a lesser extent, through the consumption of produce grown in contaminated soil, as some plants uptake certain heavy metals. For this reason, it is a great idea to learn more about your soil through the following steps: • Establish the level of concern. Assess your site, and learn more about the site history. If your site was an infill area, an orchard, a landfill, a commercial property, or near a railway, it can likely be considered “medium concern.” If it was or is nearby a gas station, dry cleaner, printing or autobody shop, rail line, industrial site, demolished buildings or renovation of old homes, or had garbage dumped or burnt, it may be considered “higher concern.” Read more about how to establish levels of concern in the City of Toronto’s “Guide for Soil Testing in Urban Gardens,” available online (see “Resources”). • Test the soil. For information on how to sample and test the soil for contamination, see activities below. • Take action to reduce risks. Questions[questions:soil] Activities[activities:soil] |
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26 | Bronwen |
February 07, 2019 22:08
| about 5 years ago
What is soil?Healthy soil is made from the following: +Minerals (45%). +Organic Matter (5%). +Water (25%). +Air (25%). It is home to countless microorganisms, plants and animals. The Soil Triangle.The soil triangle is used in the USA to classify the texture of the soil based on the amount of sand, silt & clay. Testing Soil: The Settlement Test.This is used to work out the ratio of sand: silt: clay. All you need is a soil sample, a jar and some water. 1.Take the jar and measure the volume. 2.Fill the jar about 2/3 full with water. 3.Take your soil sample & remove any big clumps of matter (e.g.sticks & stones). 4.Fill the jar with soil until it reaches the rim. 5.Put on the lid and then vigorously shake the jar until all the soil particles are mixed into the water. 6.Leave the jar for a few hours until the sediments have settled to the bottom of the jar. There should now be three distinct layers at the bottom of the jar + the water left on top. These layers should be, from the top down, cley, silt & sand. All you then have to do is to mark a line on the jar at the edge of each layer & do the math using the soil triangle above to work out the texture of your soil sample. Testing Soil: The Ribbon Test.Soils are often compacted, nutrient deficient, and can sometimes contain heavy metals and other contaminants as a result of historical industrial activity, past and present land use and nearness to pollution sources (i.e. a major road, a coal plant). We can be exposed to contaminants through soils and these can have health effects over the long term. What is a soil contaminant and where does it come from?A soil contaminant is an element (like lead) or a chemical (like diesel oil, also known as ‘organics’) present in the soil at a level that poses health risks to soil, plant, animal or human health. Contaminants can end up in your soil or on your plants through the air (dust, exhaust), water (rain, groundwater), and direct deposition (from on site or nearby polluters). **Soil contaminants include: Heavy metals (Inorganic chemicals) Heavy metals are those elements which are toxic to humans at certain concentrations, including arsenic, copper, lead, mercury, nickel, chromium, cadmium, zinc and aluminum. Some of them, like zinc and copper, are necessary or beneficial to living organisms in small concentrations but are toxic above a certain concentration; others, like lead, cadmium and mercury, serve no known biological function and are always toxic. Heavy metals are naturally occurring, found in rocks, soil systems and bedrock, and in some places a certain metal may be naturally present in higher concentrations. The majority of heavy metal contamination arises from human activity– metal mining and smelting, agrochemical fertilizers and pesticides, sewage sludge, oil and gas operations and fossil fuel burning, improper waste disposal, and fill used in residential development. Unlike organic contaminants, heavy metals cannot be broken down. (Well, except through nuclear fission!) As such, they can continue to build up in soils. But their characteristics may change so that they can be more or less easily taken up by plants or animals. Many of the practices that gardeners, especially organic gardeners, already use in their gardens- such as mulching, feeding the soil with organic matter and compost- can limit the potential for soil contaminants to be taken up in food crops. Organic Chemicals Chemical/organic contaminants are carbon-based, meaning they are derived or manufactured from something that was once alive, for example, oil and gasoline, which is the remains of plant and animal matter that was compressed for millions of years, then pumped out of the earth and processed. Polyaromatic Hydrocarbons (PAH’s) and other petroleum hydrocarbon contaminants, solvents like trichloroethylene (TCE), dioxins and Polychlorinated Biphenyls (PCB’s) are a few organic contaminants of note. They can be present in soils, particularly on or near historical or present-day auto and machine repair shops, old or leaky oil tanks, busy roads or highways, landfills and dumps, beneath electrical stations and wires, and places where there were building fires or demolished buildings. If you’re concerned you have this type of contaminant because of historical or present land use, or nearness to a busy road or auto-shop, you can get a soil test done for Total Petroleum Hydrocarbons (TPH’s), and /or Polycyclic Aromatic Hydrocarbons (PAH’s) and either avoid growing in areas of contamination, grow in raised beds, or take steps to remediate the soil (see “Earth Repair, by Leila Darwish”). Should I be concerned about soil contamination?It is likely that the soil in any urban setting will contain some level of heavy metal and organic contaminants, and long-term exposure can have health risks, particularly for children. Lead and other heavy metals in soil can enter the human body through inhalation or ingestion of dust and soil (on vegetables) and, to a lesser extent, through the consumption of produce grown in contaminated soil, as some plants uptake certain heavy metals. For this reason, it is a great idea to learn more about your soil through the following steps: • Establish the level of concern. Assess your site, and learn more about the site history. If your site was an infill area, an orchard, a landfill, a commercial property, or near a railway, it can likely be considered “medium concern.” If it was or is nearby a gas station, dry cleaner, printing or autobody shop, rail line, industrial site, demolished buildings or renovation of old homes, or had garbage dumped or burnt, it may be considered “higher concern.” Read more about how to establish levels of concern in the City of Toronto’s “Guide for Soil Testing in Urban Gardens,” available online (see “Resources”). • Test the soil. For information on how to take a soil test, see links in the “Resources” section. • Take action to reduce risks. Questions[questions:soil] Activities[activities:soil] |
Revert | |
25 | Bronwen |
February 07, 2019 22:08
| about 5 years ago
What is soil?Healthy soil is made from the following: +Minerals (45%). +Organic Matter (5%). +Water (25%). +Air (25%). It is home to countless microorganisms, plants and animals. The Soil Triangle.The soil triangle is used in the USA to classify the texture of the soil based on the amount of sand, silt & clay. Testing Soil: The Settlement Test.This is used to work out the ratio of sand: silt: clay. All you need is a soil sample, a jar and some water. 1.Take the jar and measure the volume. 2.Fill the jar about 2/3 full with water. 3.Take your soil sample & remove any big clumps of matter (e.g.sticks & stones). 4.Fill the jar with soil until it reaches the rim. 5.Put on the lid and then vigorously shake the jar until all the soil particles are mixed into the water. 6.Leave the jar for a few hours until the sediments have settled to the bottom of the jar. There should now be three distinct layers at the bottom of the jar + the water left on top. These layers should be, from the top down, cley, silt & sand. All you then have to do is to mark a line on the jar at the edge of each layer & do the math using the soil triangle above to work out the texture of your soil sample. Testing Soil: The Ribbon Test.Soils are often compacted, nutrient deficient, and can sometimes contain heavy metals and other contaminants as a result of historical industrial activity, past and present land use and nearness to pollution sources (i.e. a major road, a coal plant). We can be exposed to contaminants through soils and these can have health effects over the long term. What is a soil contaminant and where does it come from?A soil contaminant is an element (like lead) or a chemical (like diesel oil, also known as ‘organics’) present in the soil at a level that poses health risks to soil, plant, animal or human health. Contaminants can end up in your soil or on your plants through the air (dust, exhaust), water (rain, groundwater), and direct deposition (from on site or nearby polluters). **Soil contaminants include: Heavy metals (Inorganic chemicals) Heavy metals are those elements which are toxic to humans at certain concentrations, including arsenic, copper, lead, mercury, nickel, chromium, cadmium, zinc and aluminum. Some of them, like zinc and copper, are necessary or beneficial to living organisms in small concentrations but are toxic above a certain concentration; others, like lead, cadmium and mercury, serve no known biological function and are always toxic. Heavy metals are naturally occurring, found in rocks, soil systems and bedrock, and in some places a certain metal may be naturally present in higher concentrations. The majority of heavy metal contamination arises from human activity– metal mining and smelting, agrochemical fertilizers and pesticides, sewage sludge, oil and gas operations and fossil fuel burning, improper waste disposal, and fill used in residential development. Unlike organic contaminants, heavy metals cannot be broken down. (Well, except through nuclear fission!) As such, they can continue to build up in soils. But their characteristics may change so that they can be more or less easily taken up by plants or animals. Many of the practices that gardeners, especially organic gardeners, already use in their gardens- such as mulching, feeding the soil with organic matter and compost- can limit the potential for soil contaminants to be taken up in food crops. Organic Chemicals Chemical/organic contaminants are carbon-based, meaning they are derived or manufactured from something that was once alive, for example, oil and gasoline, which is the remains of plant and animal matter that was compressed for millions of years, then pumped out of the earth and processed. Polyaromatic Hydrocarbons (PAH’s) and other petroleum hydrocarbon contaminants, solvents like trichloroethylene (TCE), dioxins and Polychlorinated Biphenyls (PCB’s) are a few organic contaminants of note. They can be present in soils, particularly on or near historical or present-day auto and machine repair shops, old or leaky oil tanks, busy roads or highways, landfills and dumps, beneath electrical stations and wires, and places where there were building fires or demolished buildings. If you’re concerned you have this type of contaminant because of historical or present land use, or nearness to a busy road or auto-shop, you can get a soil test done for Total Petroleum Hydrocarbons (TPH’s), and /or Polycyclic Aromatic Hydrocarbons (PAH’s) and either avoid growing in areas of contamination, grow in raised beds, or take steps to remediate the soil (see “Earth Repair, by Leila Darwish”). Should I be concerned about soil contamination?It is likely that the soil in any urban setting will contain some level of heavy metal and organic contaminants, and long-term exposure can have health risks, particularly for children. Lead and other heavy metals in soil can enter the human body through inhalation or ingestion of dust and soil (on vegetables) and, to a lesser extent, through the consumption of produce grown in contaminated soil, as some plants uptake certain heavy metals. For this reason, it is a great idea to learn more about your soil through the following steps: • Establish the level of concern. Assess your site, and learn more about the site history. If your site was an infill area, an orchard, a landfill, a commercial property, or near a railway, it can likely be considered “medium concern.” If it was or is nearby a gas station, dry cleaner, printing or autobody shop, rail line, industrial site, demolished buildings or renovation of old homes, or had garbage dumped or burnt, it may be considered “higher concern.” Read more about how to establish levels of concern in the City of Toronto’s “Guide for Soil Testing in Urban Gardens,” available online (see “Resources”). • Test the soil. For information on how to take a soil test, see links in the “Resources” section. • Take action to reduce risks. Questions[questions:soil] Activities[activities:soil] |
Revert | |
24 | DanielleS |
February 05, 2019 18:02
| about 5 years ago
What is soil?Healthy soil is made from the following: +Minerals (45%). +Organic Matter (5%). +Water (25%). +Air (25%). It is home to countless microorganisms, plants and animals. The Soil Triangle.The soil triangle is used in the USA to classify the texture of the soil based on the amount of sand, silt & clay. Testing Soil: The Settlement Test.This is used to work out the ratio of sand: silt: cley. All you need is a soil sample, a jar and some water. 1.Take the jar and measure the volume. 2.Fill the jar about 2/3 full with water. 3.Take your soil sample & remove any big clumps of matter (e.g.sticks & stones). 4.Fill the jar with soil until it reaches the rim. 5.Put on the lid and then vigorously shake the jar until all the soil particles are mixed into the water. 6.Leave the jar for a few hours until the sediments have settled to the bottom of the jar. There should now be three distinct layers at the bottom of the jar + the water left on top. These layers should be, from the top down, cley, silt & sand. All you then have to do is to mark a line on the jar at the edge of each layer & do the math using the soil triangle above to work out the texture of your soil sample. Testing Soil: The Ribbon Test.Soils are often compacted, nutrient deficient, and can sometimes contain heavy metals and other contaminants as a result of historical industrial activity, past and present land use and nearness to pollution sources (i.e. a major road, a coal plant). We can be exposed to contaminants through soils and these can have health effects over the long term. What is a soil contaminant and where does it come from?A soil contaminant is an element (like lead) or a chemical (like diesel oil, also known as ‘organics’) present in the soil at a level that poses health risks to soil, plant, animal or human health. Contaminants can end up in your soil or on your plants through the air (dust, exhaust), water (rain, groundwater), and direct deposition (from on site or nearby polluters). **Soil contaminants include: Heavy metals (Inorganic chemicals) Heavy metals are those elements which are toxic to humans at certain concentrations, including arsenic, copper, lead, mercury, nickel, chromium, cadmium, zinc and aluminum. Some of them, like zinc and copper, are necessary or beneficial to living organisms in small concentrations but are toxic above a certain concentration; others, like lead, cadmium and mercury, serve no known biological function and are always toxic. Heavy metals are naturally occurring, found in rocks, soil systems and bedrock, and in some places a certain metal may be naturally present in higher concentrations. The majority of heavy metal contamination arises from human activity– metal mining and smelting, agrochemical fertilizers and pesticides, sewage sludge, oil and gas operations and fossil fuel burning, improper waste disposal, and fill used in residential development. Unlike organic contaminants, heavy metals cannot be broken down. (Well, except through nuclear fission!) As such, they can continue to build up in soils. But their characteristics may change so that they can be more or less easily taken up by plants or animals. Many of the practices that gardeners, especially organic gardeners, already use in their gardens- such as mulching, feeding the soil with organic matter and compost- can limit the potential for soil contaminants to be taken up in food crops. Organic Chemicals Chemical/organic contaminants are carbon-based, meaning they are derived or manufactured from something that was once alive, for example, oil and gasoline, which is the remains of plant and animal matter that was compressed for millions of years, then pumped out of the earth and processed. Polyaromatic Hydrocarbons (PAH’s) and other petroleum hydrocarbon contaminants, solvents like trichloroethylene (TCE), dioxins and Polychlorinated Biphenyls (PCB’s) are a few organic contaminants of note. They can be present in soils, particularly on or near historical or present-day auto and machine repair shops, old or leaky oil tanks, busy roads or highways, landfills and dumps, beneath electrical stations and wires, and places where there were building fires or demolished buildings. If you’re concerned you have this type of contaminant because of historical or present land use, or nearness to a busy road or auto-shop, you can get a soil test done for Total Petroleum Hydrocarbons (TPH’s), and /or Polycyclic Aromatic Hydrocarbons (PAH’s) and either avoid growing in areas of contamination, grow in raised beds, or take steps to remediate the soil (see “Earth Repair, by Leila Darwish”). Should I be concerned about soil contamination?It is likely that the soil in any urban setting will contain some level of heavy metal and organic contaminants, and long-term exposure can have health risks, particularly for children. Lead and other heavy metals in soil can enter the human body through inhalation or ingestion of dust and soil (on vegetables) and, to a lesser extent, through the consumption of produce grown in contaminated soil, as some plants uptake certain heavy metals. For this reason, it is a great idea to learn more about your soil through the following steps: • Establish the level of concern. Assess your site, and learn more about the site history. If your site was an infill area, an orchard, a landfill, a commercial property, or near a railway, it can likely be considered “medium concern.” If it was or is nearby a gas station, dry cleaner, printing or autobody shop, rail line, industrial site, demolished buildings or renovation of old homes, or had garbage dumped or burnt, it may be considered “higher concern.” Read more about how to establish levels of concern in the City of Toronto’s “Guide for Soil Testing in Urban Gardens,” available online (see “Resources”). • Test the soil. For information on how to take a soil test, see links in the “Resources” section. • Take action to reduce risks. |
Revert | |
23 | DanielleS |
February 05, 2019 18:02
| about 5 years ago
What is soil?Healthy soil is made from the following: +Minerals (45%). +Organic Matter (5%). +Water (25%). +Air (25%). It is home to countless microorganisms, plants and animals. The Soil Triangle.The soil triangle is used in the USA to classify the texture of the soil based on the amount of sand, silt & clay. Testing Soil: The Settlement Test.This is used to work out the ratio of sand: silt: cley. All you need is a soil sample, a jar and some water. 1.Take the jar and measure the volume. 2.Fill the jar about 2/3 full with water. 3.Take your soil sample & remove any big clumps of matter (e.g.sticks & stones). 4.Fill the jar with soil until it reaches the rim. 5.Put on the lid and then vigorously shake the jar until all the soil particles are mixed into the water. 6.Leave the jar for a few hours until the sediments have settled to the bottom of the jar. There should now be three distinct layers at the bottom of the jar + the water left on top. These layers should be, from the top down, cley, silt & sand. All you then have to do is to mark a line on the jar at the edge of each layer & do the math using the soil triangle above to work out the texture of your soil sample. Testing Soil: The Ribbon Test.Soils are often compacted, nutrient deficient, and can sometimes contain heavy metals and other contaminants as a result of historical industrial activity, past and present land use and nearness to pollution sources (i.e. a major road, a coal plant). We can be exposed to contaminants through soils and these can have health effects over the long term. What is a soil contaminant and where does it come from?A soil contaminant is an element (like lead) or a chemical (like diesel oil, also known as ‘organics’) present in the soil at a level that poses health risks to soil, plant, animal or human health. Contaminants can end up in your soil or on your plants through the air (dust, exhaust), water (rain, groundwater), and direct deposition (from on site or nearby polluters). **Soil contaminants include: Heavy metals (Inorganic chemicals) Heavy metals are those elements which are toxic to humans at certain concentrations, including arsenic, copper, lead, mercury, nickel, chromium, cadmium, zinc and aluminum. Some of them, like zinc and copper, are necessary or beneficial to living organisms in small concentrations but are toxic above a certain concentration; others, like lead, cadmium and mercury, serve no known biological function and are always toxic. Heavy metals are naturally occurring, found in rocks, soil systems and bedrock, and in some places a certain metal may be naturally present in higher concentrations. The majority of heavy metal contamination arises from human activity– metal mining and smelting, agrochemical fertilizers and pesticides, sewage sludge, oil and gas operations and fossil fuel burning, improper waste disposal, and fill used in residential development. Unlike organic contaminants, heavy metals cannot be broken down. (Well, except through nuclear fission!) As such, they can continue to build up in soils. But their characteristics may change so that they can be more or less easily taken up by plants or animals. Many of the practices that gardeners, especially organic gardeners, already use in their gardens- such as mulching, feeding the soil with organic matter and compost- can limit the potential for soil contaminants to be taken up in food crops. Organic Chemicals Chemical/organic contaminants are carbon-based, meaning they are derived or manufactured from something that was once alive, for example, oil and gasoline, which is the remains of plant and animal matter that was compressed for millions of years, then pumped out of the earth and processed. Polyaromatic Hydrocarbons (PAH’s) and other petroleum hydrocarbon contaminants, solvents like trichloroethylene (TCE), dioxins and Polychlorinated Biphenyls (PCB’s) are a few organic contaminants of note. They can be present in soils, particularly on or near historical or present-day auto and machine repair shops, old or leaky oil tanks, busy roads or highways, landfills and dumps, beneath electrical stations and wires, and places where there were building fires or demolished buildings. If you’re concerned you have this type of contaminant because of historical or present land use, or nearness to a busy road or auto-shop, you can get a soil test done for Total Petroleum Hydrocarbons (TPH’s), and /or Polycyclic Aromatic Hydrocarbons (PAH’s) and either avoid growing in areas of contamination, grow in raised beds, or take steps to remediate the soil (see “Earth Repair, by Leila Darwish”). Should I be concerned about soil contamination?It is likely that the soil in any urban setting will contain some level of heavy metal and organic contaminants, and long-term exposure can have health risks, particularly for children. Lead and other heavy metals in soil can enter the human body through inhalation or ingestion of dust and soil (on vegetables) and, to a lesser extent, through the consumption of produce grown in contaminated soil, as some plants uptake certain heavy metals. For this reason, it is a great idea to learn more about your soil through the following steps: • Establish the level of concern. Assess your site, and learn more about the site history. If your site was an infill area, an orchard, a landfill, a commercial property, or near a railway, it can likely be considered “medium concern.” If it was or is nearby a gas station, dry cleaner, printing or autobody shop, rail line, industrial site, demolished buildings or renovation of old homes, or had garbage dumped or burnt, it may be considered “higher concern.” Read more about how to establish levels of concern in the City of Toronto’s “Guide for Soil Testing in Urban Gardens,” available online (see “Resources”). • Test the soil. For information on how to take a soil test, see links in the “Resources” section. • Take action to reduce risks. |
Revert | |
22 | amysoyka |
July 01, 2014 06:22
| almost 10 years ago
What is soil?Healthy soil is made from the following: +Minerals (45%). +Organic Matter (5%). +Water (25%). +Air (25%). It is home to countless microorganisms, plants and animals. The Soil Triangle.The soil triangle is used in the USA to classify the texture of the soil based on the amount of sand, silt & clay. Testing Soil: The Settlement Test.This is used to work out the ratio of sand: silt: cley. All you need is a soil sample, a jar and some water. 1.Take the jar and measure the volume. 2.Fill the jar about 2/3 full with water. 3.Take your soil sample & remove any big clumps of matter (e.g.sticks & stones). 4.Fill the jar with soil until it reaches the rim. 5.Put on the lid and then vigorously shake the jar until all the soil particles are mixed into the water. 6.Leave the jar for a few hours until the sediments have settled to the bottom of the jar. There should now be three distinct layers at the bottom of the jar + the water left on top. These layers should be, from the top down, cley, silt & sand. All you then have to do is to mark a line on the jar at the edge of each layer & do the math using the soil triangle above to work out the texture of your soil sample. Testing Soil: The Ribbon Test. |
Revert | |
21 | amysoyka |
July 01, 2014 06:21
| almost 10 years ago
What is soil?Healthy soil is made from the following: Minerals (45%). Organic Matter (5%). Water (25%). Air (25%). It is home to countless microorganisms, plants and animals. The Soil Triangle.The soil triangle is used in the USA to classify the texture of the soil based on the amount of sand, silt & clay. Testing Soil: The Settlement Test.This is used to work out the ratio of sand: silt: cley. All you need is a soil sample, a jar and some water. 1.Take the jar and measure the volume. 2.Fill the jar about 2/3 full with water. 3.Take your soil sample & remove any big clumps of matter (e.g.sticks & stones). 4.Fill the jar with soil until it reaches the rim. 5.Put on the lid and then vigorously shake the jar until all the soil particles are mixed into the water. 6.Leave the jar for a few hours until the sediments have settled to the bottom of the jar. There should now be three distinct layers at the bottom of the jar + the water left on top. These layers should be, from the top down, cley, silt & sand. All you then have to do is to mark a line on the jar at the edge of each layer & do the math using the soil triangle above to work out the texture of your soil sample. Testing Soil: The Ribbon Test. |
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20 | amysoyka |
July 01, 2014 06:18
| almost 10 years ago
What is soil?Healthy soil is made from the following: Minerals (45%). Organic Matter (5%). Water (25%). Air (25%). It is home to countless microorganisms, plants and animals. The Soil Triangle.The soil triangle is used in the USA to classify the texture of the soil based on the amount of sand, silt & clay. .jpg).jpg) Testing Soil: The Settlement Test.This is used to work out the ratio of sand: silt: cley. All you need is a soil sample, a jar and some water. 1.Take the jar and measure the volume. 2.Fill the jar about 2/3 full with water. 3.Take your soil sample & remove any big clumps of matter (e.g.sticks & stones). 4.Fill the jar with soil until it reaches the rim. 5.Put on the lid and then vigorously shake the jar until all the soil particles are mixed into the water. 6.Leave the jar for a few hours until the sediments have settled to the bottom of the jar. There should now be three distinct layers at the bottom of the jar + the water left on top. These layers should be, from the top down, cley, silt & sand. All you then have to do is to mark a line on the jar at the edge of each layer & do the math using the soil triangle above to work out the texture of your soil sample. Testing Soil: The Ribbon Test. |
Revert |