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TheRealSmallBean t1_jaa4tds wrote

Oh! I can actually answer this!

Fertilizers have a lot of nitrogen and phosphorus. When they enter a waterway, that causes algae to grow really rapidly and form “algae blooms” that cover the surface of the water. This blocks sunlight and makes it harder for plants to photosynthesize, which reduces the amount of oxygen in the water. As the plants and algae die, they’re also eaten by bacteria that require oxygen which limits the amount of oxygen in the water even further. The whole process is called eutrophication.

EDIT: Thanks for the awards!! This is my first comment that’s gotten more than like ten upvotes, how fitting for it to be about something nerdy.

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edXel_l_l t1_jabnr44 wrote

OOT, but I just wanna appreciate your enthusiasm. wish I have an award to give.

Edit: OMG thanks for the awards :"

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scottshilala t1_jac3tpt wrote

The algae bloom also limits the transfer of oxygen from the air to the body of water by creating a layer that blocks adsorption. The surface agitation is dampened dramatically by the floating mats, thus lowering the uptake of oxygen by a large percentage (that I can’t remember, so I don’t want to quote it, but it’s over 50%).

More simply, the floating mats of algae cut down the oxygen and create a blocking layer so very little oxygen gets through it.

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GeorgeCauldron7 t1_jacwrdf wrote

So does the algae itself consume oxygen (aerobic respiration?), or produce oxygen (photosynthesis?) in order to survive? Sorry, I study inorganic geochemistry but don't know much of anything about biology or botany.

Is there any difference between green algae and orange algae? I monitor water quality on a few streams, and the stream with the lowest dissolved oxygen (~30%) has both green and orange algae present, while the other streams have only green algae and have DO of 70-90%.

Also, are there any other plants that have a significant matting effect that dampens oxygen dissolution? Like a pond full of lily pads?

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RedditOR74 t1_jadidze wrote

Algae does both. During the day it contributes highly to oxygenating the water, but it consumes it at night. Since it also limits he surface area to replenish the oxygen, the water goes anaerobic during night time.

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Kingreaper t1_jadjc2x wrote

> So does the algae itself consume oxygen (aerobic respiration?), or produce oxygen (photosynthesis?) in order to survive? Sorry, I study inorganic geochemistry but don't know much of anything about biology or botany. > >

The Algae both consumes and produces oxygen - at first it's necessarily producing more than it consumes, in order to get the carbon it needs to grow in size, but when it's as big as it's going to get those numbers start balancing out.

Add in the fact that dead algae decaying take oxygen solely from the water, while living algae photosynthesising put their oxygen both into the water below and the air above, and you get a net decrease in oxygen over time (barring gas transfer, which as mentioned is blocked by the matting effect)

Another part of the problem is that the algae only produces oxygen in the daytime, and consumes it constantly, so at night the oxygen level in the water drops - and if something can't survive at night-time oxygen levels then it dies, and starts decaying, further lowering the oxygen levels.

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glampringthefoehamme t1_jadkekh wrote

Can we use the algae as fertilizer? As in, direct ask runoff to large ponds with non-harmful algae, allow it to absorb the leftover nutrients, harvest abs dry the algae, and then use it as fertilizer later?

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GeorgeCauldron7 t1_jadww4u wrote

So is it safe to say that if algae is present in a body of water, then you can expect the overall effect to be a net decrease in oxygen?

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Nero1022 t1_jabztb8 wrote

I just gave reward in your place, kind stranger. :)

​

Infact, have some yourself!

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Optimal_Hunter t1_jac7he8 wrote

What does OOT mean?

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edXel_l_l t1_jac89s7 wrote

Out of Topic. I wasn't contributing nor adding anything whatsoever, but I was commending his eagerness to explain something he knew.

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EquivalentCommon5 t1_jabn47x wrote

This is why it’s a great thing to have buffers for waterways, tiered gardens that funnel water runoff to be used again and not get into waterways. Other things that can help keep runoff out of waterways! But if the US can manage that, we still have animal fecal runoff (which can be mitigated but isn’t as much as should be), company pollution- which they can pay for off sets. Off sets aren’t available to farmers iirc, could be wrong! We need to supplement farmers not so many companies!!! Farmers feed us, companies- ugh, some ‘feed’ us but big corporations get major breaks that local farmers don’t! Wish people started to really look at what makes the US great. Unfortunately, they won’t! Liberals don’t see where their food comes from, conservatives don’t see how great diversity helps us, neither side on the outskirts seem to realize that politicians are about themselves. Politicians get away with bribes, stock fraud (buying knowing more than the public, pretty much corruption though there are other terms, insider trading comes to mind), oh not paying back loans that were for small business to stay afloat during the pandemic, or they get different health care, salaries and pensions that don’t make sense… they retire as millionaires. Sorry went off on a tangent I shouldn’t have. Summary from this- politicians on every side have a 70% chance of being corrupt in someway!

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sweetpotatokumquat t1_jaby1pl wrote

One thing that annoys me about the rise of agrocorp is how the deck is stacked against existing farmers.

We know that tiered taxation systems are generally a good thing, where individuals who earn more pay progressively higher percentages in tax. They still take home more money overall by earning more, but it shifts the burden of income tax away from those who have the least.

This doesn't happen for corporations. The mom and pop farm managing 2 hectares is paying the same tax rate as HappyValleyAgroCorp which manages 100000 hectares spread across the country.

But it gets worse. Mom and pop either have old inefficient equipment they've inherited, or have to rent in equipment when needed, cause they can't afford to drop $500k on a new tractor that will get used for 50 days a year. So they're paying more for their equipment than HappyValleyAgroCorp which has their own fleet of gear that's in constant use.

Mom and pop are stuck paying whatever price the local farmer supply store charges for feed and fertiliser. HappyValleyAgroCorp is buying so much that they can negotiate heavily with suppliers and ship stuff in from across the country.

Mom and pop will struggle to access any subsidies that might be available, either having to jump through hoops or simply not knowing about them. HappyValleyAgroCorp's got a lawyer on retainer who goes golfing with the subsidy administrator.

Mom and pop are stuck taking whatever price HappyValleyGroceryCorp offers them for their produce. HappyValleyAgroCorp is pumping out so much produce for cheaper costs that they can undercut mom and pop into the ground, and negotiate higher wholesale rates by threatening to disrupt HappyValleyGroceryCorp's supply chains. But they hash it out over their weekly golf round, and the only ones that get hurt are mom and pop and us buying groceries.

And so mom and pop are stuck working for very little their entire lives, until they die, and their kids are left with a tiny farm that brings in very little, and forced to choose between slaving away like mom and pop did, or sell off the land to HappyValleyAgroCorp who's willing to step in with "quite a reasonable offer really for this tiny plot, in cash, cause we know in this difficult time you don't want to be wasting time dealing with this. It's what mom and pop would have wanted, that the land continues to be farmed."

And 40 years later, we still think of farmers as mom and pop but really it's 3 or 4 mega corps owning the entire thing.

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Trewarin t1_jabov1t wrote

There is also a lot of acid production during the phases where bacterial like organisms convert agricultural ammonia into nitrites, and then nitrates, especially if oxygenation of the waterway is low or temps high. The pH swing also kills fish rapidly

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PastelFlamingo150 t1_jabrh47 wrote

Are there animals that eat the algae rather than let bacteria decompose it? Is there a way to reinforce a food chain with the algae at the bottom such that it replenishes fish stocks or whale populations?

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pdpi t1_jabz6p9 wrote

“Can we solve the problem with one invasive species by adding another invasive species?” Is well-documented as a disastrous strategy

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gl00mybear t1_jacv0mz wrote

Specifically in this case, why the Illinois river is infested with carp.

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GeorgeCauldron7 t1_jacw5i8 wrote

Don't worry, when winter rolls around, the gorillas simply freeze to death.

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PastelFlamingo150 t1_jac0fox wrote

That's not at all what I'm talking about. I'm talking about using the wasted nutrition to rebuild oceanic food chains from the bottom up while simultaneously pulling CO2 out of the atmosphere.

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Kaisermeister t1_jac3dbk wrote

You are directionally thinking of a geoengineering method called ocean fertilization. Using iron in the middle of the ocean where plankton normally couldn’t grow to stimulate blooms.

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PastelFlamingo150 t1_jac5ut1 wrote

That sounds very expensive compared to utilizing free fertilizer runoff.

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Kaisermeister t1_jac6us1 wrote

Fertilizer is much more expensive to produce than iron which is cheap and plentiful. Using runoff would be much more expensive (extremely so) as they would have to build millions of miles of piping and collection systems, evaporate it out, and transport it into the middle of the ocean.

And in the end, the effects would be minimal, since the nutrient the phytoplankton are limited by is usually iron.

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PastelFlamingo150 t1_jacd7ua wrote

What about setting up at the mouth of the rivers? I imagine the operation would be easier if it was operating in New Orleans rather than Midway.

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madbird406 t1_jacqiur wrote

Eutrophication already occurs at these places, because of, again, overabundance of fertilizer runoff and plankton growth. They often create "dead zones" that cause marine life to suffocate when they pass through.

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PastelFlamingo150 t1_jacsey2 wrote

Right. I'm asking if there is a way to avoid the dead zones by having something further up the food chain eat the algae before the bacteria rots them. Someone had suggested filter feeding shell fish.

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TheRealSmallBean t1_jacrwg5 wrote

I’m not sure if there is some animal that can “fix” it, but I know one of the biggest problems is that the lack of oxygen kills fish. If there’s an abundance of food, the fish will reproduce at rates that the oxygen in the water can’t support. It’s a good idea though!

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flareblitz91 t1_jacb8m8 wrote

Slightly less ELI5 expansion: Nitrogen and Phosphorous are both considered “limiting nutrients” basically every ecosystem on the planet is limited by one of these two nutrients, naturally speaking phosphorous only comes from the weathering of minerals and bio available nitrogen only comes from nitrogen fixings bacteria in anaerobic environments (such as nodes in some symbiotic plant roots) and lightning…until the invention of the Haber-Bosch process the amount of useable nitrogen on earth was functionally fixed….people were scraping guano off of rocks to make TNT…

Anyway, with industrial processes and fertilizers we’ve cranked these nutrients up to 11 to disastrous result on the environment, seriously this might be worse than climate change unless we stop what we’re doing (we won’t).

Nutrient pollution not only causes these aquatic issues, it can also heavily favor invasive species, as native plants are typically adapted well to a specific environment, which includes nutrient availability, invasive plants more suited to higher nutrients can take advantage of higher levels of available nitrogen and phosphorous, grow rapidly and displace the native plants.

This is actually one of the reasons why wetlands are so critically important, not only to they tend to collect the nutrient pollution and prevent it from being washed downstream, they are also a critical site for nutrient cycling, in this case specifically Denitrification.

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FakeLoveLife t1_jaby99q wrote

So algae thriving will end up killing algae? Thats quite interesting

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Patmarker t1_jacqduv wrote

It’s the natural order of all things. Good conditions for any organism will allow it to reproduce and grow the population rapidly. They’ll then use up all the resources and go through a massive population crash, after which the population tends to recover towards a stable level.

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alreadyhaveanaccou t1_jabznks wrote

Ambrose Furey couldn't have said it better himself. There'd be a tangent about Domoic acid though.

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where-is-sam-today t1_jac9r9l wrote

Oh! And i can reverse the problem!

The process is called amelioration - it comprises of two stages - aeration, and bio manipulation.

Compressed Ozone is funnelled through tubes to the bottom of the lake / water body, and is released through stainless steel disks. It completes the oxidation process of the decay/ decomposition of organic matter all the way from the depth to the surface. Decayed matter starts to surface and is collected. Gradually the lake literally "vomits" out the crap. That's aeration.

All this while the water quality is measured, and once it reaches optimum level, specific species of fishes are introduced , and that's bio manipulation.

The lake shines again!🍀

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arztnur t1_jac4mhd wrote

Very brief and perfect explanation. A true Eli5 should be like that.

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AnnonymousRedditor86 t1_jacimtu wrote

Thank you for explaining this so succinctly. Would you please come with me to Congress to explain this to all the states bordering the Mississippi River so that we might begin to reduce the huge dead zone in the Gulf of Mexico when half the nation's fertilizer runs off into it?

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TheRealSmallBean t1_jacs5c9 wrote

I’m in college right now to (hopefully) double major in political science and environmental studies, so that’s exactly what I want to be doing in the future!

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UntamedStream t1_jacl37e wrote

Yes! This is something that is also taught in schools nowadays (at least here in Finland)

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ColdDesert77 t1_jadayu4 wrote

Why do nitrogen and phosphorus cause algae?

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TheRealSmallBean t1_jadg90q wrote

Someone in the comments explained it really well, but plants need nitrogen and phosphorus to grow. Usually those are in limited quantities, so growth is limited by the amount available. Fertilizer is designed to provide an abundance of nitrogen and phosphorus to plants, so if those high quantities end up in the water, algae growth isn’t limited and can grow more rapidly.

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