Maximizing Carbon Sequestration in Wetlands
| 10-04-2025 00:46 | |
| Im a BM★★★★★ (2324) |
The Diminished Capacity of Wetlands as a Consequence of Human Activities. The capacities of a fully competent wetland include the ability to act as a carbon "sink" to sequester atmospheric carbon into organic carbon with a long residence time before decomposing. They also include the ability to act as a indispensable source of alkalinity, carbonate ions and bicarbonate ions, to marine ecosystems via submarine groundwater discharge. These capacities enable wetlands to reduce the concentration of greenhouse gas in the atmosphere to counter global warming, and increase the bioavailability of carbonate ion in sea water to counter the harm of ocean "acidification". Wetlands are experiencing diminished capacity as a consequence of human activity. As humans drain wetlands for agriculture, they transform them from net carbon "sinks" to become a net carbon "source" to the atmosphere. Ending the low oxygen waterlogged condition and exposing the sediment to oxygen enable aerobic decomposition and respiration to increase the output of CO2 to the atmosphere by about 50X. A 5000% increase in the rate of CO2 emitted per square meter, with NO increase to the rate of carbon sequestration via photosynthesis. The same land management practice of draining wetlands also transforms them from net exporters of alkalinity to the sea to become net exporters of sulfuric acid to the sea. Buried pyrite could not be oxidized in the low oxygen waterlogged condition. Draining the wetland and exposing the buried pyrite to oxygen enable sulfur oxidizing bacteria to transform pyrite into sulfuric acid. Human activity that induced global warming also diminished wetland capacity. Now more likely to get dry at the top during at least part of the year. This allows for more aerobic decomposition of the organic carbon into carbon dioxide. It also makes them a whole lot more prone to peat fires than they used to be, releasing a whole lot of carbon dioxide via combustion of peat organic carbon. Human activity that induced sea level rise also diminished wetland capacity. The "low" tide isn't as low as it used to be. The elevation difference between low tide and wetland soil surface isn't as great as it used to be. The hydraulic gradient that drives sulfate-rich sea water into low oxygen wetland sediment during drainage at low tide isn't as steep as it used to be. The output of alkalinity to the sea as submarine groundwater discharge is diminished. Another vicious feedback as Nature reacts to our impacts. The consequences of climate change diminish the capacity of wetlands to help combat climate change. "Our Friend the Beaver" has been doing this for millions of years already. Beaver dams create constructed wetlands, from which the effluent groundwater and surface water contain significantly higher alkalinity (carbonate ion and bicarbonate ion) than the water upstream. Humans could mimic the beaver model on a larger scale to maximize alkalinity output from, and carbon sequestration into constructed wetlands. Human alteration of natural wetlands has diminished their export of alkalinity, and countered it with significant increase to sulfuric acid exported due to pyrite oxidation where the waterlogged soil has been drained to become aerobic. Better management of drained wetlands can dramatically reduce carbon dioxide emissions, decrease their export of sulfuric acid to surface waters, and increase their export of alkalinity in groundwater flows. The waterlogged conditions of wetlands impede entry of oxygen into the soil, creating low oxygen conditions where it is difficult for organic matter to decompose. Instead, new organic matter accumulates, year after year, sequestering significant carbon dioxide from the atmosphere. Conversely, massive amounts of carbon dioxide are released when wetlands are drained, allowing oxygen to enter into the soil. Total CO2 emissions to the atmosphere from drained peatlands of Southeast Asia rival total CO2 emissions from automobile engines. Establishing new wetlands is easy, but there are some potential chemical pitfalls to be aware of - potential release of arsenic and potential generation of methyl mercury. The more widespread risk is for arsenic. It is abundant many soil parent materials where new wetlands might be established. The risk, however, is only if wells tap shallow groundwater for human consumption. Otherwise, its benign where it is. The more dangerous risk, with bitter lessons having already been learned, is that the newly constructed wetland becomes a source of methyl mercury to surface water and aquatic life, and on up the food chain. In relatively rare sites where human activity has caused iron-bound mercury to accumulate under aerobic conditions (downstream from mercury mines or gold mining activities), creating a new wetland carries great risk. Under aerobic conditions, most solid-phase arsenic that contacts soil solution and groundwater is ferric-iron-bound arsenate. It is stable and benign under aerobic conditions. However, if it becomes waterlogged and low oxygen conditions prevail, that arsenic can be unleashed into solution through reductive dissolution of the ferric iron it is bound to. Toxic levels of arsenic in groundwater can be generated. However, this water is generally too salty to use for agriculture or human consumption anyway. Mercury mines generate acidic discharge. Pyrite oxidation generates sulfuric acid and ferric iron. Cinnabar oxidation generates sulfuric acid dissolved mercury. Ferric iron is soluble at high concentration in the strongly acidic mine discharge. As soon as the acid mine discharge hits near neutral pH stream water, iron floc begins to form as ferric iron forms oxyhydroxide precipitates. Dissolved mercury is sequestered and bound into the iron floc, removing nearly all of it from the stream water. Mercury-bearing iron floc then accumulated downstream in aerobic soil conditions. When folks decide to "remediate" the old mercury mine sites, they discovered the hard way that installing a new wetland downstream is a very bad idea. When mercury-bearing iron oxyhydroxide floc in aerobic soil is flooded into a low oxygen condition, iron reducing bacteria use ferric iron as oxidant to get energy from oxidation of organic carbon. This dissolves the solid-phase ferric iron, releasing it as soluble ferrous iron. Reductive dissolution of the ferric iron also releases the mercury that was bound to it. Under such conditions, the only way that iron-reducing can access the ferric iron for use as oxidant is to come into close contact with mercury. Iron reducing bacteria methylate mercury. Where the old mercury mine waste deposits had been benign for a century and a half, they had now become a source of methyl mercury for the food chain. The most relevant posts of this thread are compiled, beginning 3/4 way down page 3 |
| 10-04-2025 07:16 | |
Into the Night ★★★★★(23078) |
Im a BM wrote: Carbon is not a sink. Carbon is not organic. Carbon does not decompose. Im a BM wrote: Alkalinity is not a chemical. Carbonate is not a chemical. Bicarbonate is not a chemical. Im a BM wrote: Carbonate is not a chemical. Acidification it not a chemical. You can't acidify an alkaline. No gas or vapor has the capability to warm the Earth. You are ignoring the 1st law of thermodynamics again. Im a BM wrote: Carbon is not a sink. Carbon is not a source. Carbon is not carbon dioxide Argument from randU fallacy. Im a BM wrote: Alkalinity is not a chemical. Im a BM wrote: What 'global warming'??? It is not possible to measure the temperature of the Earth. What 'wetland capacity'??? Im a BM wrote: Carbon is not organic. Carbon dioxide cannot warm the Earth. You are still ignoring the 1st law of thermodynamics. Im a BM wrote: The sea isn't rising. Sulfate is not a chemical. Alkalinity is not a chemical. Im a BM wrote: Climate cannot change. There is nothing to 'combat'. Im a BM wrote: Beavers are often serious pests. People shoot them if they find them on their land. Im a BM wrote: Alkalinity is not a chemical. Carbonate is not a chemical. Bicarbonate is not a chemical. Im a BM wrote: Alkalinity is not a chemical. Carbon is not a sequester. Im a BM wrote: Alkalinity isnot a chemical. Pyrite does not export anything. Im a BM wrote: Carbon dioxide cannot warm the Earth. Alkalinity is not a chemical. Im a BM wrote: Carbon dioxide is not a sequester. Carbon dioxide cannot warm the Earth. It is absolutely essential for life on Earth. Im a BM wrote: Arsenic is easily detected and treated, if found in well water. Well water is not a wetland. Wetlands are not methyl mercury. Wetlands are not arsenic. Im a BM wrote: Stop spamming. The Parrot Killer Debunked in my sig. - tmiddles Google keeps track of paranoid talk and i'm not on their list. I've been evaluated and certified. - keepit nuclear powered ships do not require nuclear fuel. - Swan While it is true that fossils do not burn it is also true that fossil fuels burn very well - Swan |
| 10-04-2025 18:41 | |
| Im a BM★★★★★ (2324) |
The Diminished Capacity of Wetlands as a Consequence of Human Activities. The capacities of a fully competent wetland include the ability to act as a carbon "sink" to sequester atmospheric carbon into organic carbon with a long residence time before decomposing. They also include the ability to act as a indispensable source of alkalinity, carbonate ions and bicarbonate ions, to marine ecosystems via submarine groundwater discharge. These capacities enable wetlands to reduce the concentration of greenhouse gas in the atmosphere to counter global warming, and increase the bioavailability of carbonate ion in sea water to counter the harm of ocean "acidification". Wetlands are experiencing diminished capacity as a consequence of human activity. As humans drain wetlands for agriculture, they transform them from net carbon "sinks" to become a net carbon "source" to the atmosphere. Ending the low oxygen waterlogged condition and exposing the sediment to oxygen enable aerobic decomposition and respiration to increase the output of CO2 to the atmosphere by about 50X. A 5000% increase in the rate of CO2 emitted per square meter, with NO increase to the rate of carbon sequestration via photosynthesis. The same land management practice of draining wetlands also transforms them from net exporters of alkalinity to the sea to become net exporters of sulfuric acid to the sea. Buried pyrite could not be oxidized in the low oxygen waterlogged condition. Draining the wetland and exposing the buried pyrite to oxygen enable sulfur oxidizing bacteria to transform pyrite into sulfuric acid. Human activity that induced global warming also diminished wetland capacity. Now more likely to get dry at the top during at least part of the year. This allows for more aerobic decomposition of the organic carbon into carbon dioxide. It also makes them a whole lot more prone to peat fires than they used to be, releasing a whole lot of carbon dioxide via combustion of peat organic carbon. Human activity that induced sea level rise also diminished wetland capacity. The "low" tide isn't as low as it used to be. The elevation difference between low tide and wetland soil surface isn't as great as it used to be. The hydraulic gradient that drives sulfate-rich sea water into low oxygen wetland sediment during drainage at low tide isn't as steep as it used to be. The output of alkalinity to the sea as submarine groundwater discharge is diminished. Another vicious feedback as Nature reacts to our impacts. The consequences of climate change diminish the capacity of wetlands to help combat climate change. "Our Friend the Beaver" has been doing this for millions of years already. Beaver dams create constructed wetlands, from which the effluent groundwater and surface water contain significantly higher alkalinity (carbonate ion and bicarbonate ion) than the water upstream. Humans could mimic the beaver model on a larger scale to maximize alkalinity output from, and carbon sequestration into constructed wetlands. Human alteration of natural wetlands has diminished their export of alkalinity, and countered it with significant increase to sulfuric acid exported due to pyrite oxidation where the waterlogged soil has been drained to become aerobic. Better management of drained wetlands can dramatically reduce carbon dioxide emissions, decrease their export of sulfuric acid to surface waters, and increase their export of alkalinity in groundwater flows. The waterlogged conditions of wetlands impede entry of oxygen into the soil, creating low oxygen conditions where it is difficult for organic matter to decompose. Instead, new organic matter accumulates, year after year, sequestering significant carbon dioxide from the atmosphere. Conversely, massive amounts of carbon dioxide are released when wetlands are drained, allowing oxygen to enter into the soil. Total CO2 emissions to the atmosphere from drained peatlands of Southeast Asia rival total CO2 emissions from automobile engines. Establishing new wetlands is easy, but there are some potential chemical pitfalls to be aware of - potential release of arsenic and potential generation of methyl mercury. The more widespread risk is for arsenic. It is abundant many soil parent materials where new wetlands might be established. The risk, however, is only if wells tap shallow groundwater for human consumption. Otherwise, its benign where it is. The more dangerous risk, with bitter lessons having already been learned, is that the newly constructed wetland becomes a source of methyl mercury to surface water and aquatic life, and on up the food chain. In relatively rare sites where human activity has caused iron-bound mercury to accumulate under aerobic conditions (downstream from mercury mines or gold mining activities), creating a new wetland carries great risk. Under aerobic conditions, most solid-phase arsenic that contacts soil solution and groundwater is ferric-iron-bound arsenate. It is stable and benign under aerobic conditions. However, if it becomes waterlogged and low oxygen conditions prevail, that arsenic can be unleashed into solution through reductive dissolution of the ferric iron it is bound to. Toxic levels of arsenic in groundwater can be generated. However, this water is generally too salty to use for agriculture or human consumption anyway. Mercury mines generate acidic discharge. Pyrite oxidation generates sulfuric acid and ferric iron. Cinnabar oxidation generates sulfuric acid dissolved mercury. Ferric iron is soluble at high concentration in the strongly acidic mine discharge. As soon as the acid mine discharge hits near neutral pH stream water, iron floc begins to form as ferric iron forms oxyhydroxide precipitates. Dissolved mercury is sequestered and bound into the iron floc, removing nearly all of it from the stream water. Mercury-bearing iron floc then accumulated downstream in aerobic soil conditions. When folks decide to "remediate" the old mercury mine sites, they discovered the hard way that installing a new wetland downstream is a very bad idea. When mercury-bearing iron oxyhydroxide floc in aerobic soil is flooded into a low oxygen condition, iron reducing bacteria use ferric iron as oxidant to get energy from oxidation of organic carbon. This dissolves the solid-phase ferric iron, releasing it as soluble ferrous iron. Reductive dissolution of the ferric iron also releases the mercury that was bound to it. Under such conditions, the only way that iron-reducing can access the ferric iron for use as oxidant is to come into close contact with mercury. Iron reducing bacteria methylate mercury. Where the old mercury mine waste deposits had been benign for a century and a half, they had now become a source of methyl mercury for the food chain. The most relevant posts of this thread are compiled, beginning 3/4 way down page 3 |
| 11-04-2025 12:03 | |
| Im a BM★★★★★ (2324) |
The Diminished Capacity of Wetlands as a Consequence of Human Activities. The capacities of a fully competent wetland include the ability to act as a carbon "sink" to sequester atmospheric carbon into organic carbon with a long residence time before decomposing. They also include the ability to act as a indispensable source of alkalinity, carbonate ions and bicarbonate ions, to marine ecosystems via submarine groundwater discharge. These capacities enable wetlands to reduce the concentration of greenhouse gas in the atmosphere to counter global warming, and increase the bioavailability of carbonate ion in sea water to counter the harm of ocean "acidification". Wetlands are experiencing diminished capacity as a consequence of human activity. As humans drain wetlands for agriculture, they transform them from net carbon "sinks" to become a net carbon "source" to the atmosphere. Ending the low oxygen waterlogged condition and exposing the sediment to oxygen enable aerobic decomposition and respiration to increase the output of CO2 to the atmosphere by about 50X. A 5000% increase in the rate of CO2 emitted per square meter, with NO increase to the rate of carbon sequestration via photosynthesis. The same land management practice of draining wetlands also transforms them from net exporters of alkalinity to the sea to become net exporters of sulfuric acid to the sea. Buried pyrite could not be oxidized in the low oxygen waterlogged condition. Draining the wetland and exposing the buried pyrite to oxygen enable sulfur oxidizing bacteria to transform pyrite into sulfuric acid. Human activity that induced global warming also diminished wetland capacity. Now more likely to get dry at the top during at least part of the year. This allows for more aerobic decomposition of the organic carbon into carbon dioxide. It also makes them a whole lot more prone to peat fires than they used to be, releasing a whole lot of carbon dioxide via combustion of peat organic carbon. Human activity that induced sea level rise also diminished wetland capacity. The "low" tide isn't as low as it used to be. The elevation difference between low tide and wetland soil surface isn't as great as it used to be. The hydraulic gradient that drives sulfate-rich sea water into low oxygen wetland sediment during drainage at low tide isn't as steep as it used to be. The output of alkalinity to the sea as submarine groundwater discharge is diminished. Another vicious feedback as Nature reacts to our impacts. The consequences of climate change diminish the capacity of wetlands to help combat climate change. "Our Friend the Beaver" has been doing this for millions of years already. Beaver dams create constructed wetlands, from which the effluent groundwater and surface water contain significantly higher alkalinity (carbonate ion and bicarbonate ion) than the water upstream. Humans could mimic the beaver model on a larger scale to maximize alkalinity output from, and carbon sequestration into constructed wetlands. Human alteration of natural wetlands has diminished their export of alkalinity, and countered it with significant increase to sulfuric acid exported due to pyrite oxidation where the waterlogged soil has been drained to become aerobic. Better management of drained wetlands can dramatically reduce carbon dioxide emissions, decrease their export of sulfuric acid to surface waters, and increase their export of alkalinity in groundwater flows. The waterlogged conditions of wetlands impede entry of oxygen into the soil, creating low oxygen conditions where it is difficult for organic matter to decompose. Instead, new organic matter accumulates, year after year, sequestering significant carbon dioxide from the atmosphere. Conversely, massive amounts of carbon dioxide are released when wetlands are drained, allowing oxygen to enter into the soil. Total CO2 emissions to the atmosphere from drained peatlands of Southeast Asia rival total CO2 emissions from automobile engines. Establishing new wetlands is easy, but there are some potential chemical pitfalls to be aware of - potential release of arsenic and potential generation of methyl mercury. The more widespread risk is for arsenic. It is abundant many soil parent materials where new wetlands might be established. The risk, however, is only if wells tap shallow groundwater for human consumption. Otherwise, its benign where it is. The more dangerous risk, with bitter lessons having already been learned, is that the newly constructed wetland becomes a source of methyl mercury to surface water and aquatic life, and on up the food chain. In relatively rare sites where human activity has caused iron-bound mercury to accumulate under aerobic conditions (downstream from mercury mines or gold mining activities), creating a new wetland carries great risk. Under aerobic conditions, most solid-phase arsenic that contacts soil solution and groundwater is ferric-iron-bound arsenate. It is stable and benign under aerobic conditions. However, if it becomes waterlogged and low oxygen conditions prevail, that arsenic can be unleashed into solution through reductive dissolution of the ferric iron it is bound to. Toxic levels of arsenic in groundwater can be generated. However, this water is generally too salty to use for agriculture or human consumption anyway. Mercury mines generate acidic discharge. Pyrite oxidation generates sulfuric acid and ferric iron. Cinnabar oxidation generates sulfuric acid dissolved mercury. Ferric iron is soluble at high concentration in the strongly acidic mine discharge. As soon as the acid mine discharge hits near neutral pH stream water, iron floc begins to form as ferric iron forms oxyhydroxide precipitates. Dissolved mercury is sequestered and bound into the iron floc, removing nearly all of it from the stream water. Mercury-bearing iron floc then accumulated downstream in aerobic soil conditions. When folks decide to "remediate" the old mercury mine sites, they discovered the hard way that installing a new wetland downstream is a very bad idea. When mercury-bearing iron oxyhydroxide floc in aerobic soil is flooded into a low oxygen condition, iron reducing bacteria use ferric iron as oxidant to get energy from oxidation of organic carbon. This dissolves the solid-phase ferric iron, releasing it as soluble ferrous iron. Reductive dissolution of the ferric iron also releases the mercury that was bound to it. Under such conditions, the only way that iron-reducing can access the ferric iron for use as oxidant is to come into close contact with mercury. Iron reducing bacteria methylate mercury. Where the old mercury mine waste deposits had been benign for a century and a half, they had now become a source of methyl mercury for the food chain. The most relevant posts of this thread are compiled, beginning 3/4 way down page 3 |
| RE: The Diminished Capacity of Wetlands as a Consequence of Human Activities14-04-2025 03:16 | |
| Im a BM★★★★★ (2324) |
The Diminished Capacity of Wetlands as a Consequence of Human Activities. The capacities of a fully competent wetland include the ability to act as a carbon "sink" to sequester atmospheric carbon into organic carbon with a long residence time before decomposing. They also include the ability to act as a indispensable source of alkalinity, carbonate ions and bicarbonate ions, to marine ecosystems via submarine groundwater discharge. These capacities enable wetlands to reduce the concentration of greenhouse gas in the atmosphere to counter global warming, and increase the bioavailability of carbonate ion in sea water to counter the harm of ocean "acidification". Wetlands are experiencing diminished capacity as a consequence of human activity. As humans drain wetlands for agriculture, they transform them from net carbon "sinks" to become a net carbon "source" to the atmosphere. Ending the low oxygen waterlogged condition and exposing the sediment to oxygen enable aerobic decomposition and respiration to increase the output of CO2 to the atmosphere by about 50X. A 5000% increase in the rate of CO2 emitted per square meter, with NO increase to the rate of carbon sequestration via photosynthesis. The same land management practice of draining wetlands also transforms them from net exporters of alkalinity to the sea to become net exporters of sulfuric acid to the sea. Buried pyrite could not be oxidized in the low oxygen waterlogged condition. Draining the wetland and exposing the buried pyrite to oxygen enable sulfur oxidizing bacteria to transform pyrite into sulfuric acid. Human activity that induced global warming also diminished wetland capacity. Now more likely to get dry at the top during at least part of the year. This allows for more aerobic decomposition of the organic carbon into carbon dioxide. It also makes them a whole lot more prone to peat fires than they used to be, releasing a whole lot of carbon dioxide via combustion of peat organic carbon. Human activity that induced sea level rise also diminished wetland capacity. The "low" tide isn't as low as it used to be. The elevation difference between low tide and wetland soil surface isn't as great as it used to be. The hydraulic gradient that drives sulfate-rich sea water into low oxygen wetland sediment during drainage at low tide isn't as steep as it used to be. The output of alkalinity to the sea as submarine groundwater discharge is diminished. Another vicious feedback as Nature reacts to our impacts. The consequences of climate change diminish the capacity of wetlands to help combat climate change. "Our Friend the Beaver" has been doing this for millions of years already. Beaver dams create constructed wetlands, from which the effluent groundwater and surface water contain significantly higher alkalinity (carbonate ion and bicarbonate ion) than the water upstream. Humans could mimic the beaver model on a larger scale to maximize alkalinity output from, and carbon sequestration into constructed wetlands. Human alteration of natural wetlands has diminished their export of alkalinity, and countered it with significant increase to sulfuric acid exported due to pyrite oxidation where the waterlogged soil has been drained to become aerobic. Better management of drained wetlands can dramatically reduce carbon dioxide emissions, decrease their export of sulfuric acid to surface waters, and increase their export of alkalinity in groundwater flows. The waterlogged conditions of wetlands impede entry of oxygen into the soil, creating low oxygen conditions where it is difficult for organic matter to decompose. Instead, new organic matter accumulates, year after year, sequestering significant carbon dioxide from the atmosphere. Conversely, massive amounts of carbon dioxide are released when wetlands are drained, allowing oxygen to enter into the soil. Total CO2 emissions to the atmosphere from drained peatlands of Southeast Asia rival total CO2 emissions from automobile engines. Establishing new wetlands is easy, but there are some potential chemical pitfalls to be aware of - potential release of arsenic and potential generation of methyl mercury. The more widespread risk is for arsenic. It is abundant many soil parent materials where new wetlands might be established. The risk, however, is only if wells tap shallow groundwater for human consumption. Otherwise, its benign where it is. The more dangerous risk, with bitter lessons having already been learned, is that the newly constructed wetland becomes a source of methyl mercury to surface water and aquatic life, and on up the food chain. In relatively rare sites where human activity has caused iron-bound mercury to accumulate under aerobic conditions (downstream from mercury mines or gold mining activities), creating a new wetland carries great risk. Under aerobic conditions, most solid-phase arsenic that contacts soil solution and groundwater is ferric-iron-bound arsenate. It is stable and benign under aerobic conditions. However, if it becomes waterlogged and low oxygen conditions prevail, that arsenic can be unleashed into solution through reductive dissolution of the ferric iron it is bound to. Toxic levels of arsenic in groundwater can be generated. However, this water is generally too salty to use for agriculture or human consumption anyway. Mercury mines generate acidic discharge. Pyrite oxidation generates sulfuric acid and ferric iron. Cinnabar oxidation generates sulfuric acid dissolved mercury. Ferric iron is soluble at high concentration in the strongly acidic mine discharge. As soon as the acid mine discharge hits near neutral pH stream water, iron floc begins to form as ferric iron forms oxyhydroxide precipitates. Dissolved mercury is sequestered and bound into the iron floc, removing nearly all of it from the stream water. Mercury-bearing iron floc then accumulated downstream in aerobic soil conditions. When folks decide to "remediate" the old mercury mine sites, they discovered the hard way that installing a new wetland downstream is a very bad idea. When mercury-bearing iron oxyhydroxide floc in aerobic soil is flooded into a low oxygen condition, iron reducing bacteria use ferric iron as oxidant to get energy from oxidation of organic carbon. This dissolves the solid-phase ferric iron, releasing it as soluble ferrous iron. Reductive dissolution of the ferric iron also releases the mercury that was bound to it. Under such conditions, the only way that iron-reducing can access the ferric iron for use as oxidant is to come into close contact with mercury. Iron reducing bacteria methylate mercury. Where the old mercury mine waste deposits had been benign for a century and a half, they had now become a source of methyl mercury for the food chain. The most relevant posts of this thread are compiled, beginning 3/4 way down page 3 |
| 02-05-2025 01:20 | |
| sealover★★★★☆ (1833) |
The Diminished Capacity of Wetlands as a Consequence of Human Activities. The capacities of a fully competent wetland include the ability to act as a carbon "sink" to sequester atmospheric carbon into organic carbon with a long residence time before decomposing. They also include the ability to act as a indispensable source of alkalinity, carbonate ions and bicarbonate ions, to marine ecosystems via submarine groundwater discharge. These capacities enable wetlands to reduce the concentration of greenhouse gas in the atmosphere to counter global warming, and increase the bioavailability of carbonate ion in sea water to counter the harm of ocean "acidification". Wetlands are experiencing diminished capacity as a consequence of human activity. As humans drain wetlands for agriculture, they transform them from net carbon "sinks" to become a net carbon "source" to the atmosphere. Ending the low oxygen waterlogged condition and exposing the sediment to oxygen enable aerobic decomposition and respiration to increase the output of CO2 to the atmosphere by about 50X. A 5000% increase in the rate of CO2 emitted per square meter, with NO increase to the rate of carbon sequestration via photosynthesis. The same land management practice of draining wetlands also transforms them from net exporters of alkalinity to the sea to become net exporters of sulfuric acid to the sea. Buried pyrite could not be oxidized in the low oxygen waterlogged condition. Draining the wetland and exposing the buried pyrite to oxygen enable sulfur oxidizing bacteria to transform pyrite into sulfuric acid. Human activity that induced global warming also diminished wetland capacity. Now more likely to get dry at the top during at least part of the year. This allows for more aerobic decomposition of the organic carbon into carbon dioxide. It also makes them a whole lot more prone to peat fires than they used to be, releasing a whole lot of carbon dioxide via combustion of peat organic carbon. Human activity that induced sea level rise also diminished wetland capacity. The "low" tide isn't as low as it used to be. The elevation difference between low tide and wetland soil surface isn't as great as it used to be. The hydraulic gradient that drives sulfate-rich sea water into low oxygen wetland sediment during drainage at low tide isn't as steep as it used to be. The output of alkalinity to the sea as submarine groundwater discharge is diminished. Another vicious feedback as Nature reacts to our impacts. The consequences of climate change diminish the capacity of wetlands to help combat climate change. "Our Friend the Beaver" has been doing this for millions of years already. Beaver dams create constructed wetlands, from which the effluent groundwater and surface water contain significantly higher alkalinity (carbonate ion and bicarbonate ion) than the water upstream. Humans could mimic the beaver model on a larger scale to maximize alkalinity output from, and carbon sequestration into constructed wetlands. Human alteration of natural wetlands has diminished their export of alkalinity, and countered it with significant increase to sulfuric acid exported due to pyrite oxidation where the waterlogged soil has been drained to become aerobic. Better management of drained wetlands can dramatically reduce carbon dioxide emissions, decrease their export of sulfuric acid to surface waters, and increase their export of alkalinity in groundwater flows. The waterlogged conditions of wetlands impede entry of oxygen into the soil, creating low oxygen conditions where it is difficult for organic matter to decompose. Instead, new organic matter accumulates, year after year, sequestering significant carbon dioxide from the atmosphere. Conversely, massive amounts of carbon dioxide are released when wetlands are drained, allowing oxygen to enter into the soil. Total CO2 emissions to the atmosphere from drained peatlands of Southeast Asia rival total CO2 emissions from automobile engines. Establishing new wetlands is easy, but there are some potential chemical pitfalls to be aware of - potential release of arsenic and potential generation of methyl mercury. The more widespread risk is for arsenic. It is abundant many soil parent materials where new wetlands might be established. The risk, however, is only if wells tap shallow groundwater for human consumption. Otherwise, its benign where it is. The more dangerous risk, with bitter lessons having already been learned, is that the newly constructed wetland becomes a source of methyl mercury to surface water and aquatic life, and on up the food chain. In relatively rare sites where human activity has caused iron-bound mercury to accumulate under aerobic conditions (downstream from mercury mines or gold mining activities), creating a new wetland carries great risk. Under aerobic conditions, most solid-phase arsenic that contacts soil solution and groundwater is ferric-iron-bound arsenate. It is stable and benign under aerobic conditions. However, if it becomes waterlogged and low oxygen conditions prevail, that arsenic can be unleashed into solution through reductive dissolution of the ferric iron it is bound to. Toxic levels of arsenic in groundwater can be generated. However, this water is generally too salty to use for agriculture or human consumption anyway. Mercury mines generate acidic discharge. Pyrite oxidation generates sulfuric acid and ferric iron. Cinnabar oxidation generates sulfuric acid dissolved mercury. Ferric iron is soluble at high concentration in the strongly acidic mine discharge. As soon as the acid mine discharge hits near neutral pH stream water, iron floc begins to form as ferric iron forms oxyhydroxide precipitates. Dissolved mercury is sequestered and bound into the iron floc, removing nearly all of it from the stream water. Mercury-bearing iron floc then accumulated downstream in aerobic soil conditions. When folks decide to "remediate" the old mercury mine sites, they discovered the hard way that installing a new wetland downstream is a very bad idea. When mercury-bearing iron oxyhydroxide floc in aerobic soil is flooded into a low oxygen condition, iron reducing bacteria use ferric iron as oxidant to get energy from oxidation of organic carbon. This dissolves the solid-phase ferric iron, releasing it as soluble ferrous iron. Reductive dissolution of the ferric iron also releases the mercury that was bound to it. Under such conditions, the only way that iron-reducing can access the ferric iron for use as oxidant is to come into close contact with mercury. Iron reducing bacteria methylate mercury. Where the old mercury mine waste deposits had been benign for a century and a half, they had now become a source of methyl mercury for the food chain. The most relevant posts of this thread are compiled, beginning 3/4 way down page 3 |
| 05-05-2025 07:01 | |
| Into the Night★★★★★ (23078) |
Stop spamming. |
Join the debate Maximizing Carbon Sequestration in Wetlands:
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