Loss of oxygen in lakes and oceans | Hacker News Reader

Loss of oxygen in lakes and oceans

sciencedaily.com

118 pointsBrajeshwar48 comments

The scientific paper underlying the article is here: https://www.nature.com/articles/s41559-024-02448-y

There's a different article, and to my mind a more readable one, here: https://www.sciencedaily.com/releases/2024/07/240715135713.h...

> "Lakes and reservoirs have experienced oxygen losses of 5.5% and 18.6% respectively since 1980. The oceans have experienced oxygen losses of around 2% since 1960 and, although that number is smaller, it represents a more geographically and volumetrically extensive mass. Marine ecosystems have also experienced substantial variability in oxygen depletion. For example, the midwaters off of Central California have lost 40% of their oxygen in the last few decades."

If that holds true worldwide, and not just at a selection of measuring sites, it's a rapid and very concerning shift. It'll be interesting to see if their measurements are corroborated.

Skimming the conclusion of the paper it seems that, unless there are overlooked measurement errors the effect is robust. The immediate question this suggests to me is this: are there any naturally occurring multi-year (or multi-decade) oxygen concentration cycles in the ocean analogous to already-known salinity cycles?

This was where I immediately started thinking. Is this something that cyclical? The article is long on effect and very short on causes.

"Reducing greenhouse gas emissions, nutrient runoff and organic carbon inputs (for example, raw sewage loading) would slow or potentially reverse deoxygenation," they write.

And what exactly is "raw sewage loading" they talk about as a way to reverse this? I did some quick googling and couldn't find anything about what exactly it is.

“raw sewage loading” is, I believe, an example of an organic carbon input that should be reduced.

In other words, stop letting raw sewage out into rivers. We’ve been working on that for decades.

I wonder if "raw sewage loading" includes traditional septic systems where there's just a leach field for ... raw sewage...

There are certainly technologies these days that allow you to filter the effluent to make it less harmful to the environment.

https://www.nutter.com/trending-newsroom-publications-massde...

a leach field aproximates wetland, and with some revisioning, can be made to emulate wetland, and will often facilitate succession to actual wetland.

I read that as a clarification of organic carbon inputs that could be reduced. I don't know the specific phrase "raw sewage loading," but in context I assume its something to do with sewage waste being released into rivers and oceans.

This article seems to be based on quite a technical paper but my reading is hot water holds less oxygen so global warming is a factor. Also excess organic matter from farming is causing oxygen loss as it decomposes to CO2 and a few other processes.

It's literally what it sounds like: dumping untreated sewage into waterways and oceans.

A big problem in all of these is adding nitrogen and phosphorus to the water, which facilitates algae growth, which consumes a lot of the available oxygen:

https://oceanservice.noaa.gov/education/tutorial_pollution/0...

Urine and feces are great sources of nutrients - good if you extract them, sterilize, and use responsibly on land, not good if you dump directly into water.

there is a natural phenomenon known as wetland. these things reclaim, and redistributex raw materials that are like rocket fuel for microbes. these wetlands are inconvienient for [growth] as they take up a lot of area, andget in the way of housing developments, parking lots, and sewage treatment plants.

the solution is attempted dilution,thus:

>>It's literally what it sounds like: dumping untreated sewage into waterways and oceans.<<

Data point: IIRC the Great Lakes were getting choked on algae until they banned phosphates in detergents. And of course there is always fertilizer runoff.

Reducing carbon inputs would slow or reverse this. Increasing sewage runoff would make the problem worse.

Raw sewage contamination is a huge problem:

https://environmentamerica.org/center/resources/safe-for-swi...

Don't go swimming too soon after it rains if you want to be safe from E. coli. Overdevelopment, underfunded utilities, and factory farms put runoff at a level that's barely tolerable when it's dry, and when there's excess surface water, they overflow in unsanitary ways that result in nutrient blooms and oxygen depletion.

Thanks! I've switched the URL above to your second link (instead of the absurdly baity https://www.sciencealert.com/earths-water-is-rapidly-losing-...).

"Relevant, critical oxygen thresholds are being approached at rates comparable to other planetary boundary processes."

https://www.researchgate.net/publication/372847863_Anoxia_Be... is a previous paper, I can't find this. The author is qualified and has produced a good deal of original and field research on the topic.

This is a good example of where just reacting to a bad or clickbait headline would be to your detriment. This actually is new information and bad news.

Isn't part of the reason we stopped using bunker fuel with such high sulfur levels because it caused acidification? That also greatly damages oxygen available to organisms, I think?

I forget exactly how hypoxia and acidification are related but they're often mentioned together. For example, https://www.eea.europa.eu/en/newsroom/news/warming-acidifica...

This paper seems to be saying that low Dissolved Oxygen can quickly turn into or make acidification issues worse, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4892234/

I'm not a biologist, so I'm curious to understand the implication of less oxygen in water. I can intuitively think that less life will survive, but what else happens? Is there a way to "inject" oxygen into the ocean?

This applies to oceans and freshwater.

Hot water holds less oxygen then cold water. Oxygen, by itself, happily will go into solution with H2O if conditions are favorable. We can "inject" oxygen by slowing and reversing global warming.

One of my ponds has issues with low oxygen in the summer, the pond is too shallow and it can overheat when it's 95F and sunny out.

We lost quite a few fish last year (our first summer here). The pond also ends up with duckweed covering most of the surface - from what I've found duckweed does well in a low oxygen environment and does actually help to cool down and reoxygenate back into the water. When the duckweed overgrows, though, it blocks out too much light and can lead to an algae bloom that is really bad for the whole system.

I built a solar powered pond fountsin a month ago, it only runs for a few hours a day but seems to be helping quite a bit so far.

I raise this only to show how much can happen when a half acre pond is low on oxygen. On the scale of an ocean, I have to expect that it would take much more to get to that level of a problem, but if it did get there the cascading issues would have to be exponentially worse too.

> I built a solar powered pond fountsin a month ago

Interesting! What kind of aeration/water exchange/GPM are you finding effective for a half acre pond?

I would love to click your links. :)

I used a submersible pump rated for 6,900 GPH[1], no clue how accurste that rating is but it moves plenty of water.

I haven't had it long enough to say for sure that it's enough water flow for this size pond. Time will tell, but so far it does seem to have helped with duckweed we had a hot and dry couple of weeks.

I don't have a any links to the project or anything unfortunately. We don't use social media and haven't made the time to setup a website for our hobby farm.

[1] https://www.amazon.com/gp/aw/d/B0B4W2C44V?psc=1&ref=ppx_pop_...

Understood, and I appreciate. I've been ruminating on solutions to a very similar-sounding problem for a few summers, so your practical experience is helpful, thank you!

320W it says. So I wonder what kind of solar panel are you using?

I started with Renogy's 400W kit, 1,000W inverter, and a deep cycle marine battery. That's actually the main reason I only run it for a few hours a day right now, I knew I was pushing the wattage limits of the panels.

I'll probably end up adding a couple more 100W panels, August will really let me know whether this can do enough work to keep the pond cooler and more oxygenated.

Gas solubility in water decreases pretty strongly due to the gaseous phase being more entropic (in governing thermodynamic potentials the entropic term is -T•∆S). Unfortunately this is unavoidable with rising temperatures.

With 1 degree? Honest question. Is clear that is some places is more, but also some places (ask me how I know) are colder. The avg. is “just” 1 degree.

>Across all aquatic ecosystems, from streams and rivers, lakes, reservoirs, and ponds to estuaries, coasts, and the open ocean, dissolved oxygen (DO) concentrations have rapidly and substantially declined in recent decades. Lakes and reservoirs have experienced oxygen losses of 5.5% and 18.6% respectively since 1980. The oceans have experienced oxygen losses of around 2% since 1960 and, although that number is smaller, it represents a more geographically and volumetrically extensive mass.

>For example, the midwaters off of Central California have lost 40% of their oxygen in the last few decades.

As the oxygen carrying capacity of water is very low, an increase in temperature, that increases the overall consumption rates of organisms near the surface, could cause large magnitude changes in DO concentrations.

No numbers on how much O is needed and how it has developed the last few years?

Re: developed over the last few years, I clicked through 2 layers of referenced articles to get to the actual paper which says oxygen is down 2% on the last 50 years [1]. The rapid falling of oxygen seems to be (as far as I can tell from the various linked articles) is somewhat localized to the Gulf of St. Lawrence [2].

[1] https://www.nature.com/articles/s41558-018-0263-1

[2] https://www.sciencealert.com/this-stretch-of-water-is-losing...

So it's no longer H2O but just H2?

eating less meat seems like the biggest thing individuals can do here. Animal waste/fertilizer runoff/agricultural waste seems like the biggest contributor.

any other suggestions?

Regenerative agriculture. No till, no spray, cover crops. Managed grazing of ruminants and poultry on the same land that crops are grown on to build top soil and serve as pest control.

Regenerative ag is a ton of work, and at least in my anecdotal experience I didn't see any meaningful gains from it.

We rotated our cows once or twice a day, carefully tracking how much space they got each day based on the animals' weight and quality of forage. The animals got by okay, but honestly they seemed to act more like prisoners than cows. It shows even when you watch some of the biggest names in regenerative move their animals - the animals dive past the line into the space. Those animals are hungry and stressed by being so densely kept that they feel they need to eat before it's all gone.

Today we keep our cows in what anyone else would consider a much too low stocking density. We move them occasionally between 3 different pastures, on the order of weeks or months between each move. The animals seem less stressed, they're definitely happier, and they've created familial bonds and hierarchy that wasn't obvious when we kept them in closer quarters with frequent moves.

I'd caveat this by saying eating less industrially raised and processed meat would help. The same goes for industrial produce though, they cause a ton of damage that few people ever see or think about.

If we want realistic solutions, they'll all be incremental like using less plastic or Turing lights off when you aren't home. If we want recommendations that would actually help, we would need to completely reorganize societies and our daily lives.

We don't need cars, air travel, grocery stores, or even air conditioning to survive. Those are all modern inventions on the order of decades old. People aren't going to do that willingly though, including me. I live a very different, and more simple, life than the average American but the idea of throwing out so many things that we have today only because we've enslaved natural fuel sources is scary as hell.

Whatever the solutions are, let's not push burden on the individual. Resources are like highway lanes: even if you don't drive your car, someone will use it just.

Vote for politicians who want to do something about climate change and convince others to do the same.

I love how my comment gets flagged for pointing out the original rage bait headline. Then the headline is changed. What a bunch of shit.

It's plausible but needs quantification. I doubt it's been truly overlooked.

i can't read the article but this seems like a strange conclusion

there should be more dissolved oxygen as water becomes warmer, i thought climate change was the big disaster we were supposed to be worried about?

less dissolved oxygen would suggest the water is cooler

Someone failed highschool chemistry. More gas can dissolve in cold water vs hot. The opposite of solids.

you know what, i did

This is incorrect. When dissolving a gas into a liquid, the colder the liquid is, the more gas can be dissolved.

>there should be more dissolved oxygen as water becomes warmer,

Oxygen solubility in water is inversely correlated with temperature and salinity.

Tell ya what, take two cans of coke. One, just open and pour into a glass. The second, pour into a glass and microwave it for a couple minutes. Take a sip of each and let us know how much gas is in each glass.

There's a reason that Starbucks isn't selling hot nitro brew.

Alternate, positive headline "Earth's water sinking more carbon, oxygen loss shows".

CO2 is a potent fertilizer and is going to cause a lot of "blooms" and general more life which is going to affect oxygen levels. Loss of oxygen is a dampening effect on this.

Every environmental article has to be about "danger" instead of just stating facts about what is happening now.

It seems fairly straightforward to claim that significantly changing water chemistry is very bad, or at least very risky, for aquatic ecosystems many of whose species are very sensitive to water chemistry.

The "positive" here is supposed to be that widespread destruction of land ecosystems might be even more severe if not for the oceans also taking some of the damage? (I doubt that is true in the long run. Many global processes are dependent on functioning living oceans.)

Kind of like how fertilizer runoff is a good thing since it causes algae blooms, and more life is good right? Except that it disrupts existing ecosystems and can cause vast oxygen-free dead zones.

One of the things we should be doing is intentionally fertilizing oceans, particularly the "deserts" where not much grows at all, as an intentional way to cause blooms and sink carbon.

Yes, let's not stop doing the thing that we know is destroying our ecosystem, and instead, lets try a mass geoengineering effort when we are incapable of knowing what unintended side effects will happen when we do it on a large scale.

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