| 23-04-2022 17:38 |
IBdaMann ★★★★★
(14389) |
GasGuzzler wrote:Did you know they didn't actually eat the forbidden fruit?
I know. They were actually performing forbidden animal testing with the resin from the peel, and Yahweh just wasn't having it. Yes, IBDaMann was called to testify in court. So, IBDaMann is sworn in as an expert witness to testify in federal court. Credentials and other irrefutable qualifications clarified.
So, the PhD engineer set the standards for chemical analysis to be used to identify which materials are hazardous to water quality.
Using a citrate buffer, it is possible to extract alarmingly high concentrations of potentially toxic metals from forbidden fruit sediments exposed to oxidation.
According to Dr. BS, this PROVES that the forbidden fruit sediments cause contamination of surface waters.
According to Dr. BS, this proves that forbidden fruit sediments CANNOT BE USED AS EYE MASCARA.
That's going to make it hard to apply the makeup as was the case with Freddy Mercury.
According to Dr. BS, the results from the citrate buffer extraction PROVE that dredged sediments must be stored as potentially hazardous waste, at an incredibly high cost.
But Dr. BS was just BS'ing.
When IBDaMann pointed out that citrate anion formed an inner sphere chelation complex with the potentially toxic forbidden fruit of concern, the look on Dr. BS face was worth a million dollars.
He had no idea what the gibber babble buzzwords meant!
He had no response that would mean shit in federal court.
The dredged sediments were reclassified back again as useful, safe makeup application material.
The citrate buffer test was rescinded as a predictor of toxicity to surface waters.
Dr. BS had been sitting on his little throne for years and years.
"IBDaMann" pointed out that the emperor had no clothes, and the jury agreed.
Sven was spared MILLIONS OF DOLLARS OF USELESS MITIGATION COSTS.
A paradise was spared having to search far and wide for material to apply mascara for the costume plot for performances and rehearsals, and to shore up the garden as sea level rises.
GasGuzzler wrote: Some of the seeds they planted, but the majority were sent to a galaxy far far away via catapult for future generations.
GasGuzzler, you should know better. Not by catapult. By trebuchet! You're going to have to answer to Into the Night for that one. |
| 05-06-2023 08:46 |
Im a BM★★★☆☆
(595) |
sealover wrote:
Wetlands are among the world's most productive ecosystems. High rates of photosynthesis sequester atmospheric carbon dioxide to become organic carbon in the live biomass. Waterlogged wetland soils create low oxygen conditions that prevent aerobic decomposition of organic carbon in dead biomass. Wetland soil organic matter has centuries long mean residence time, piling up year after year.
Undisturbed wetlands act as a net sink for carbon, sequestering more of it from the atmosphere than they emit by respiration or decomposition.
When wetlands are drained, stored organic carbon is exposed to oxygen and aerobic decomposition. Drained wetlands act as a net source for carbon, emitting more carbon dioxide to the atmosphere than they sequester from it. Indeed, they emit carbon dioxide to the atmosphere at a rate orders of magnitude higher than the rate at which they sequester it.
This seems like a good place to start the discussion |
| RE: recap05-06-2023 08:47 |
Im a BM★★★☆☆
(595) |
sealover wrote:
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.
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. |
| RE: recap05-06-2023 08:48 |
Im a BM★★★☆☆
(595) |
sealover wrote:
Into the Night wrote:
sealover wrote:
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.
There you go on about carbon dioxide. You haven't yet explained the problem with it.
sealover wrote:
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.
Why establish new wetlands? To limit carbon dioxide? Why do you hate plants?
-------------------------------------------------------------------------------
Why establish new wetlands? To limit carbon dioxide?
Downstream from the mercury mine, nobody was trying to sequester carbon dioxide from the atmosphere.
For decades already, people had been constructing wetlands for the sole purpose of neutralizing acid mine drainage.
Because wetlands generate alkalinity.
The problem was that it had become so routine a prescription, they thought they had to do it where the actual acid discharge had nearly ceased more than a century before.
So, if you ask an environmental engineer "Why establish new wetlands?", the answer would often be because they neutralize acidity.
If you ask someone such as myself, in the context of ocean acidification, "Why establish new wetlands?"
Because they neutralize acidity. |
| RE: recap05-06-2023 08:50 |
Im a BM★★★☆☆
(595) |
sealover wrote:
IBdaMann wrote:
sealover wrote:It was actually government oversight that f****d up the situation to release methyl mercury from the wetland they required the landowner to construct.
That how they "remediate" by the book.
Then what is to be done?
--------------------------------------------------------------------
So, what is to be done?
In this case, they did the right thing to correct the mistake.
First, they contracted some of the world's most respected biogeochemists (tee hee!) to investigate what went wrong.
They recognized the limits of their own knowledge and sought information and advice from experts.
They followed that advice. Success story.
They broke the dam to allow aerobic conditions to reestablish.
Reductive dissolution, methylation and release of the mercury from the sediment ceased. |
|
| RE: recap05-06-2023 08:51 |
Im a BM★★★☆☆
(595) |
sealover wrote:
Into the Night wrote:
sealover wrote:
Into the Night wrote:
sealover wrote:
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.
There you go on about carbon dioxide. You haven't yet explained the problem with it.
sealover wrote:
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.
Why establish new wetlands? To limit carbon dioxide? Why do you hate plants?
-------------------------------------------------------------------------------
Why establish new wetlands? To limit carbon dioxide?
Downstream from the mercury mine, nobody was trying to sequester carbon dioxide from the atmosphere.
So? They are interested in collecting mercury ore.
sealover wrote:
For decades already, people had been constructing wetlands for the sole purpose of neutralizing acid mine drainage.
What acid mine drainage?
sealover wrote:
Because wetlands generate alkalinity.
You can't generate alkalinity.
sealover wrote:
The problem was that it had become so routine a prescription, they thought they had to do it where the actual acid discharge had nearly ceased more than a century before.
Acid is not a discharge.
sealover wrote:
So, if you ask an environmental engineer "Why establish new wetlands?", the answer would often be because they neutralize acidity.
What acidity?
sealover wrote:
If you ask someone such as myself, in the context of ocean acidification, "Why establish new wetlands?"
You can't acidify an alkaline. There is no such context.
sealover wrote:
Because they neutralize acidity.
What acidity?
------------------------------------------------------------------
"Acid Mine Discharge" or AMD is a real thing.
This was a mine that was closed about 150 years ago. They were not interested in trying to collect any more ore. Cinnabar is the main mercury ore. Comprised entirely of mercury and sulfur. Another way to name it is mercury pyrite. Like any other pyrite, its sulfide content can be oxidized by sulfur oxidizing bacteria, using oxygen, to generate sulfuric acid. They can really do that. But there would have been no cinnabar to find in the mercury-enriched iron floc downstream.
What acid mine drainage?
The strongly acidic drainage that came out of the mine. Dissolved in water kind of thing.
That's why they construct the wetlands - to remediate AMD.
Because wetlands do the impossible - they "generate alkalinity". |
| RE: recap05-06-2023 08:54 |
Im a BM★★★☆☆
(595) |
sealover wrote:
tmiddles wrote:
sealover wrote:wetlands...they emit carbon dioxide to the atmosphere at a rate orders of magnitude higher than the rate at which they sequester it.
Isn't it a fixed amount?
Like to keep it simple let's say there is a small forest. It grows to be a certain size and the biomass contains let's say a million tons of CO2.
If the forest stops getting larger the death of trees would equal the growth and it would stop being a net absorber of CO2.
If the whole forest burns, or rots, the entire million tons is released.
If you bury the forest and plant a new one on top of it, that million tons is now sequestered underground and you can grow another million.
Sound about right?
[u]
-----------------------------------------------------------------
Excellent question.
If I understand your question, it is based on misinterpreting a little which fluxes were referred to.
A wetland is constantly aggrading - gaining more and more organic carbon and storing it as peat. Year after year.
In this condition, the amount of CO2 released by decomposition is less than the amount sequestered by photosynthesis.
After draining and exposure to oxygen, the amount of CO2 released by decomposition is orders of magnitude greater than CO2 sequestered by photosynthesis.
But the values are rate. CO2 fluxes per unit time. Not total fluxes.
Does that help? |
| RE: recap05-06-2023 08:57 |
Im a BM★★★☆☆
(595) |
sealover wrote:
NBC News Mangrove Story Missed the Mark.
Tuesday night, April 18, NBC news ran a story about carbon sequestration in mangroves.
They tried, but the story missed the mark.
I had high hopes when the graphic showed "5x as much carbon as rainforests"
Yes, mangroves have higher net primary productivity than rainforests, but no way is it FIVE times as much.
Then the story implied that mangroves "piped" carbon dioxide underground through the roots. Seemed to imply that it was stored underground in the form of carbon dioxide.
Still, I had hope when they said that there was ANOTHER important role of mangroves in global ecology.
I couldn't wait for them to mention alkalinity exported to marine ecosystems from mangrove swamps via submarine groundwater discharge.
But then, their "5x as much carbon" would have had to be "30-40x as much carbon", compared to rainforest export of alkalinity from the same land area.
But then, the story went on to discuss WHALE MIGRATION and the importance of mangroves.
I love whales as much as the next guy, but...
So, there IS public awareness that natural ecosystems, such as mangrove swamps, can sequester carbon dioxide and this could be important.
Good start.
But the presentation of numbers involved was misleading.
And furthermore, there are MANY kinds of ecosystems that cover much larger land area than mangroves, including agroecosystems.
What mangroves do that is so desperately needed is to act as a MAJOR SOURCE
of ALKALINITY to marine ecosystems.
Someday the news stories will finally pick up on it.
And, hopefully, stop talking about ocean "acidification" as if pH rather than depletion of acid neutralizing capacity (alkalinity) were the issue.
With the sea's enormous buffering capacity from the carbonate system, pH shifts from anthropogenic acid inputs are TINY compared to alkalinity losses.
At least mangrove finally got some attention in the news.
The more we clear mangrove swamps and drain them, the less alkalinity they can provide to the sea. Indeed, a drained swamp becomes a net source of ACID to the sea, as pyrite is exposed to oxygen and oxidized to sulfuric acid.
--------------------------------------------------------------------------------
sealover wrote:
Wetlands are among the world's most productive ecosystems. High rates of photosynthesis sequester atmospheric carbon dioxide to become organic carbon in the live biomass. Waterlogged wetland soils create low oxygen conditions that prevent aerobic decomposition of organic carbon in dead biomass. Wetland soil organic matter has centuries long mean residence time, piling up year after year.
Undisturbed wetlands act as a net sink for carbon, sequestering more of it from the atmosphere than they emit by respiration or decomposition.
When wetlands are drained, stored organic carbon is exposed to oxygen and aerobic decomposition. Drained wetlands act as a net source for carbon, emitting more carbon dioxide to the atmosphere than they sequester from it. Indeed, they emit carbon dioxide to the atmosphere at a rate orders of magnitude higher than the rate at which they sequester it.
This seems like a good place to start the discussion |
| RE: recap05-06-2023 08:58 |
Im a BM★★★☆☆
(595) |
[quote]sealover wrote:
Annual Ammonification of Dead Microbial Biomass in drained wetlands.
Acid neutralizing processes in wetlands include sulfate reduction and nitrate reduction.
However, other nitrogen transformations can have a tremendous, although only very brief, impact on alkalinity and pH.
Many places where wetlands have been drained have a pronounced annual wetting and drying cycle.
During the dry season, microbial biomass in the upper topsoil dries out and dies off.
When the rains come again, that dead biomass gets rewetted and a feeding frenzy begins.
Dead microbial biomass has a C:N ratio of about 10:1. One atom of nitrogen for every ten atoms of carbon.
Microorganisms only need a little of the nitrogen, but they want to burn up the organic carbon.
First, they have to ammonify it. Amino groups have to be torn away from carbon, to get access to the energy rich material. Ammonium and very high pH are generated. The pH can go as high as 11, for a little while.
In the presence of oxygen, some of that ammonium starts to get oxidized to nitric acid almost immediately.
By the time that nitrate leaches down into the subsoil and groundwater, all the associated organic carbon has generated low oxygen conditions.
Nitrate reduction down below generates alkalinity in the groundwater.
But timing is everything.
If the first rains of the season are not heavy, not enough water will pile up to drive any down into groundwater. Ammonification, etc., all occur above, without any of the products entering the subsoil. By the time the rains get heavy enough to drive it into groundwater, it is no longer such a high energy mix.
When the first rains of the season are HEAVY, high loads of dissolved organic carbon induce reductive dissolution of ferric-iron-bound arsenic. Groundwater arsenic skyrockets, at least temporarily.
When the first rains are LIGHT, low loads of dissolved organic carbon enter the groundwater, and arsenic concentrations remain lower.
I like to compare it to deliberately setting a wildfire at a time of year when the fuel is moist enough to support only a low intensity burn.
We can lightly irrigate the drained wetland field in ADVANCE of the first heavy rain, for a dissolved organic carbon "fuel" load that supports only a low intensity "burn" when it enters groundwater. Less arsenic, less manganese, cleaner groundwater. |
| RE: recap05-06-2023 08:59 |
Im a BM★★★☆☆
(595) |
sealover wrote:
Temporary Extreme High pH with Ammonification - the numbers added up.
It was December, 2005. The rains finally came, and they came in force with a record setting storm.
I had to go to the field to get samples while they were fresh, and conditions were miserable.
I couldn't believe the pH readings. 10. 10.5 11 WTF?
There was an equipment screw up and one sample bottle only got half full.
It had way too much air and oxygen for proper protocols and was set aside rather than immediately put on ice.
We already had field data for the sample (pH, redox, salinity, temperature, etc).
This particular sample had the highest pH of all. 11.3
Upon arrival to the lab, a last minute decision was made to go ahead and include the messed up sample, just to find out what was in it.
It would not be a "reportable" result because proper protocols were not followed, but it could shed light on an unexpected phenomenon.
By the time the lab analyzed it, the oxygen in the air space of the sample bottle had already reacted with it.
The pH went from 11.3 in the field to just above 3 in the lab.
Ammonium had been oxidized by bacteria to nitric acid.
The nitrate values explained it all. Highest ever seen in any related sample.
Indeed, the numbers added up perfectly to explain why pH 3 would be expected from that much nitrification.
The other samples, which had no air space and were immediately put on ice, had virtually no nitrate. Just ammonium.
So, the wetland soil acid-base puzzle includes multiple interactions between multiple players.
Sulfate reduction and nitrate reduction may be the largest sources of alkalinity in wetland groundwater discharged to the sea.
But other processes, such as the ammonification of dead microbial biomass, can also have important short-term impacts on pH and alkalinity. |
| RE: recap05-06-2023 09:01 |
Im a BM★★★☆☆
(595) |
[quote]sealover wrote:
Thermogenic Bacteria - Hot Ground Water
December, 2005, when a record-setting storm brought the first real rain of the year.
When I arrived to the field to meet up with T, I noticed a lot of local places with ground level fog. Then I noticed that the fog was billowing up from the ground in a few places. They weren't peat fires. What was it?
T had already started collecting at the newest monitor well. Steam was coming off the sample.
I pointed out how odd it was. He told me that the water was even hotter when he purged the well to collect the sample. The new samples were barely above body temperature. Still way too hot for groundwater.
This one was the brand new well. Could it be a chemical reaction from the bentonite used to seal the well?
But then all the OTHER wells had warm steamy groundwater too.
What is the perfect niche for a thermogenic bacteria?
Well, they need a truly ABUNDANT food supply, because they are going to spend a whole lot of energy to heat up their surroundings.
Dead microbial biomass is the most nutritious energy-rich food out there.
Go ahead and waste a lot of calories to generate heat. This will bake off the competition who can't take the heat.
I had never seen them do that outside of a compost pile before.
That was the ONLY sampling event when thermogenic bacteria made themselves evident while I was there to see it. |
| RE: recap05-06-2023 09:03 |
Im a BM★★★☆☆
(595) |
sealover wrote:
Placer Mining and First US Environmental Regulations.
Society didn't always agree that government needed to impose environmental regulations.
The California Gold Rush was one of wildest chapters in the wild wild west.
The "yellow metal that drives the white men crazy" brought a lot of fortune seekers to California.
They were willing to do ANYTHING to get it.
By the 1870s, large scale placer mining was blasting away the hillsides of the Mother Lode.
The waterways of the Sacramento-San Joaquin Delta became clogged with sediments washed down from the Mokelumne River.
The shipping channels could no longer be used for shipping.
Draconian government overreach was agreed upon, even by the wealthiest.
Laws were put in place to protect the waterways.
No more placer mining.
Even more draconian government overreach to make the waterways navigable again for shipping.
A whole system of levees and drains, still maintained by the US Army Corps of Engineers (USACE).
Those USACE guys are actually pretty cool. I worked with many of them.
They were the indirect source of my paychecks while I investigated the biogeochemistry of the dredged sediments, ground water, and surface water.
But until the 1870s, people were allowed to trash the environment legally. |
| RE: recap05-06-2023 09:05 |
Im a BM★★★☆☆
(595) |
[quote]sealover wrote:
Rice Paddies and Anabaena azollae Cyanobacteria.
Humans have terraformed by constructing rice paddies, for thousands of years.
These agroecosystems sustained productivity without anthropogenic inputs of agricultural chemicals, for thousands of years.
A large, coordinated social network was required to maintain the system of dikes and canals. This made people work together under a central government.
One reason these rice paddies work so well is due to the presence of azolla water ferns.
The aquatic azolla fern lives in symbiosis with a nitrogen fixing bacteria, Anabaena azollae.
This "blue green algae" is also photosynthetic, like the fern it lives with.
Atmospheric nitrogen can be "fixed" by these cyanobacteria, into a form that eventually becomes bioavailable to the rice in the paddies.
It costs a lot of energy to "fix" nitrogen. Legumes have to provide carbohydrate to the nitrogen fixing bacteria in the nodules on their roots to be able to do it.
These water ferns and their bacterial partners make rice production possible without humans having to apply nitrogen fertilizer.
Rice paddies take a lot of work to build.
Perhaps the most impressive can be found on steep mountain slopes of Bali.
Far more difficult to build than the rice paddies of Southeast Asian deltas, these are on steep hillsides.
It would have been much easier to build them on lower land, irrigated with river water.
But the groundwater on the slopes of these mountains in Bali is special.
It is highly enriched in phosphorus.
It was worth the effort to build the rice paddy infrastructure with such fertile water coming in.
Because they also have the azolla fern with its cyanobacteria to supply nitrogen. |
| 05-06-2023 09:08 |
Im a BM★★★☆☆
(595) |
[quote]sealover wrote:
Wetlands are among the world's most productive ecosystems. High rates of photosynthesis sequester atmospheric carbon dioxide to become organic carbon in the live biomass. Waterlogged wetland soils create low oxygen conditions that prevent aerobic decomposition of organic carbon in dead biomass. Wetland soil organic matter has centuries long mean residence time, piling up year after year.
Undisturbed wetlands act as a net sink for carbon, sequestering more of it from the atmosphere than they emit by respiration or decomposition.
When wetlands are drained, stored organic carbon is exposed to oxygen and aerobic decomposition. Drained wetlands act as a net source for carbon, emitting more carbon dioxide to the atmosphere than they sequester from it. Indeed, they emit carbon dioxide to the atmosphere at a rate orders of magnitude higher than the rate at which they sequester it. |
| 05-06-2023 19:41 |
Into the Night ★★★★★
(21588) |
I guess sealover (and Im a BM) feels like talking to himself.
Carbon isn't organic.
You still haven't define 'carbon sequestering'.
Carbon isn't carbon dioxide.
No gas or vapor is capable of warming the Earth.
You can't create energy out of nothing. |
|
| RE: two very different approaches to carbon sequestration23-06-2023 11:23 |
sealover★★★★☆
(1239) |
[quote]sealover wrote:
Wetlands are among the world's most productive ecosystems. High rates of photosynthesis sequester atmospheric carbon dioxide to become organic carbon in the live biomass. Waterlogged wetland soils create low oxygen conditions that prevent aerobic decomposition of organic carbon in dead biomass. Wetland soil organic matter has centuries long mean residence time, piling up year after year.
Undisturbed wetlands act as a net sink for carbon, sequestering more of it from the atmosphere than they emit by respiration or decomposition.
When wetlands are drained, stored organic carbon is exposed to oxygen and aerobic decomposition. Drained wetlands act as a net source for carbon, emitting more carbon dioxide to the atmosphere than they sequester from it. Indeed, they emit carbon dioxide to the atmosphere at a rate orders of magnitude higher than the rate at which they sequester it.
-------------------------------------------------------------------------------------
Buried beneath wetlands is an enormous reservoir of organic carbon, accumulated over centuries.
Another thread, "Maximizing carbon sequestration in terrestrial agroecosystems", is focused on aerobic soils, to which wetland dynamics do not apply.
In a wetland, the waterlogged condition impedes the entry of oxygen into the soil, preventing aerobic decomposition (respiration). The chemistry of the vegetation is not what regulates carbon sequestration in wetlands.
The other thread gets into the vegetation chemistry that DOES regulate carbon sequestration in aerobic soils, with very limited application to wetlands.
Globally, the drainage of wetlands for agriculture, particularly the peatlands of southeast Asia, is a MAJOR source of additional carbon dioxide emission to the atmosphere. It rivals fossil fuel combustion and deforestation for the first place slot in anthropogenic carbon dioxide emissions. |
| 23-06-2023 14:49 |
IBdaMann★★★★★
(14389) |
sealover wrote:... particularly the peatlands of southeast Asia, is a MAJOR source of additional carbon dioxide emission to the atmosphere.
What constitutes a MAJOR source of CO2?
Are you claiming that CO2 from this source is somehow NOT readily and greedily consumed by other plantlife?
sealover wrote: It rivals fossil fuel combustion
What are you including in all this and what are you excluding?
sealover wrote:and deforestation for the first place slot in anthropogenic carbon dioxide emissions.
How are peatlands "anthropogenic"? What does that word mean? |