Wikipedia:Reference desk/Archives/Science/2018 April 8

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April 8

Water conservation and drought

Season 13 Episode 4 of The TV show Ask This Old House was a special on drought. (I looked for a link to the full episode, but all I could find was this trailer: http://www.pbs.org/video/ask-old-house-ask-old-house-practical-solutions-drought-promotion/ .) In this episode, and as can be seen in the trailer, the hosts visited Lake Mead, which was at about 40% of capacity providing visual images of how drought is impacting the lake. Through the rest of the show a variety of approaches to mitigating drought are covered. One of which was reducing consumption with things like low flow toilets.

This brings me to my question - I'd like to learn more about how low flow toilets help lakes mitigate drought. While this is a completely intuitive concept - using less of something leaves more behind - wouldn't increased flushed water go through a water treatment system and then be released possibly make it's way back to the lake? Is there a good place to learn what happens to water after it is released from the water treatment system?

As with most things science, this is no doubt a broad topic. General understanding is good enough. — Preceding unsigned comment added by 68.10.227.183 (talk) 04:25, 8 April 2018‎

Naturally, Wikipedia has an article on that. Well, at least two that seem relevant, Low-flush toilet and Dual flush toilet, plus the See alsos and links attached to those articles. Dual flush toilets are now almost ubiquitous in Australia, where they were developed. Australia is a very dry continent. It simply doesn't have the spare water to be finding its way through treatment plants. Interestingly, I've seen Australian made dual flush toilets at Grand Canyon Village, Arizona, where the available fresh water is a mile below, at the bottom of the canyon, and in San Pedro de Atacama in Chile, where the average annual rainfall is around 1.7 inches. So they seem to have their place. HiLo48 (talk) 05:40, 8 April 2018 (UTC)

Wastewater, even treated, is generally not released into drinking reservoirs. It's released "downstream" into rivers or the ocean. Of course, Earth always has the same amount of water (excepting the odd meteor or comet), so the water may find its way back eventually, but "in the long run we're all dead". Reclaimed water is used in some places for irrigation and other non-potable uses, and interest is growing in "closing the loop" and treating effluent to potability, but doing so takes more resources so it's not widespread. --47.146.63.87 (talk) 06:17, 8 April 2018 (UTC)

Also, even if a system is in place to recycle wastewater to make it drinkable again, doing so isn't free, so you still want to conserve water. If you're paying for the water, conserving saves you money too. --47.146.63.87 (talk) 06:21, 8 April 2018 (UTC)

Good thing you've never been to London then. The average Thames River water molecule is 'recycled' 8 times by the time it gets to the North Sea. Greglocock (talk) 11:49, 8 April 2018 (UTC)

One city treats its sewage to whatever extent the law requires, while trying to keep costs down, then releases it to flow downstream in a river where another city uses it as it intake, treats it to make it safe for drinking (one hopes) then the process is repeated. St Louis. Missouri uses the effluent from Chicago and other cities upstream in the Mississippi and Illinois rivers, for instance, for over 80% of its drinking water supply. It is not correct to claim that the output of the toilet is treated and then used only for irrigation, while somehow virgin water from collected rain and ancient aquifers supplies your next glass of drinking water. You are drinking the processed pee from upstream cities if you live in many major cities getting their water from rivers. Edison (talk) 13:12, 8 April 2018 (UTC)

Even if your water comes from a well, chances are that somewhere close by someone is treating waste water and pumping it into the aquifer. And in the long run, the cup of coffee you had this morning contains a small amount of water that used to be T-Rex piss. Here on the Southern border of Los Angeles, they are doing something interesting. At the very bottom layer of our aquifer there is a layer of "brown water". It looks like tea, and is colored by the fact that ancient redwoods have been soaking for a very long time. They pump it up, treat it so that it is as good as any drinking water anywhere, then re-inject it a few miles away in a line of injection wells to stop seawater from encroaching on the aquifer. --Guy Macon (talk) 00:14, 9 April 2018 (UTC)

Yes, I know that. I guess I wasn't explicit enough. My point was wastewater is generally not looped right back into the water system. It seemed to me the questioner believed this was common. --47.146.63.87 (talk) 08:35, 11 April 2018 (UTC)

Thanks all. Good points. Question answered. 128.229.4.2 (talk) 18:34, 9 April 2018 (UTC)

Is there really such a thing as a cold fever?

I've just read in a Sanskrit text: "Fever is of two kinds, viz. that with a feeling of cold and that with a feeling of heat. Fever with a feeling of cold should be represented by Consequents such as shivering, tremors of the entire body, bending [the body], shaking of the jaws, narrowing down the nasal passage, dryness of the mouth, horripilation, lamentation and the like. And that with a feeling of heat is to be represented by throwing out clothes, the hands and the feet, desire [to roll on] the ground, [use of] unguent, desire for coolness, lamentation, crying and the like." Now this is not a medical text, but a text about theater. But are these recognizable medical symptoms? Is there really such a thing as a cold fever? If yes, what accounts for the difference if the temperature of the body is the same in both cold and hot fever? Thanks. Basemetal 13:54, 8 April 2018 (UTC)

Fever doesn't talk much about the subjective experience, though chills does describe how many people can experience a feeling of coldness during high fever. Here [1] is a discussion about how sometimes people feel hot during fever, and sometimes cold. Here's another piece on that. [2]. It seems to me your quote is describing two different ways of feeling/acting during fever, and it would seem to me that there is ample support for two different broad tendencies of subjective feeling that occur, with at least some physiological support. SemanticMantis (talk) 14:25, 8 April 2018 (UTC)

Interesting! Neither our article Fever nor Sickness behavior go into this. Personally, I feel so much colder during any fever that I'd always assumed it was in substantial part a behavioral response (as it is in reptiles) and I had discounted movie scenes of people who feel hot during fevers as Hollywood ignorance. Well... Wnt (talk) 16:16, 8 April 2018 (UTC)

During fever or when the fever abates? That's what I'm trying to find out. What people describe as feeling cold during fever is it really when the temperature is high or when the temperature finally abates?

The source above suggested you feel cold when the fever is in effect and hot when it abates. I certainly feel cold all throughout a fever - to the point of huddling under blankets on hot summer days - personally I don't feel hot when a fever breaks, though it makes me sweat when it does and stops that behavior. But I wouldn't doubt people who say they do, but then they're not hot (in my mind) because they have a fever but because they don't. Wnt (talk) 21:18, 8 April 2018 (UTC)

That does rather sound like a description of intermittent fever - and certainly reminds me of what it felt like to have malaria. Wymspen (talk) 16:42, 8 April 2018 (UTC)

Which one? Basemetal 19:18, 8 April 2018 (UTC)

I am envious of your ignorance regarding fevers. :) Yes, there are "cold" and "hot" fevers, though I don't know the mechanism driving those sensations. For example, during my last visit from influenza, I felt horribly chilled and unbearably hot at different times, but the thermometer insisted I was running a fever in both cases. Cold fever felt worse, but could at least be partly ameliorated with blankets and tea. For hot fever, I was at least partially out of it the whole time. Matt Deres (talk) 21:21, 8 April 2018 (UTC)

Not a big fan of flu shots I take it? You should try one. In Canada they're free for many people and probably reasonably priced for all. Basemetal 21:49, 8 April 2018 (UTC)

They're free to anyone who has a valid health card; it's just that the shots are not perfect in what they cover and they don't last forever. I got sick in early fall (several years ago), before that year's batch was available. I do get them regularly, though, and encourage others to do so. Matt Deres (talk) 14:01, 9 April 2018 (UTC)

• There are many other puzzling descriptions in that text. Here's another one, that of the consequences of a snake bite or taking poison: "In case of snake-bite or taking poison [there is gradual] development of its symptoms which are eight in number, viz. thinness (of the body), tremor, burning sensation, hiccough [sic], foam from the mouth, breaking of the neck, paralysis and death". Again, this is not a medical text. It is a theatrical manual supposed to tell you how to act those things on stage. I just can't imagine how you act "thinness of the body" (especially if you're fat), or "horripilation", or "dryness of the mouth", or (in other places) "change of color"... Maybe there are some conventional means to symbolize those things (such as hastamudras and the like) but it's not clear (there isn't much that is clear in that text). Also: "breaking of the neck"? How can that be a consequence of a snakebite? The Sanskrit word this is supposed to translate (skandhabhaMgaH स्कन्धभङ्गः) literally means "breaking of the shoulder". Maybe what is meant is the fact that your head is slumped on your shoulder as if your neck could no longer support its weight. (Is that a consequence of poisoning or a snakebite?) In which case "breaking of the neck" would be a bad translation because to break your neck means something else entirely in English. Basemetal 19:18, 8 April 2018 (UTC)

The article malaria mentions an alternation between shivering and fever. Malaria was the first thing I thought of when I saw the question. 173.228.123.166 (talk) 21:58, 8 April 2018 (UTC)

Range of the king cobra?

The maps I've seen usually agree in showing a discontinuous distribution for the king cobra (note: the text of the article contradicts most maps by stating that this snake is found "across the Indian subcontinent"): a small area on the coast of Kerala and Karnataka (those guys are in the minority but they seem to be the most famous; maybe you've seen that video of a king cobra being given water from a bottle by a wildlife ranger from Karnataka) and then all the rest. Some maps (not all) also show a small isolated pocket in south-west China. What can explain a discontinuous range like this? Only extinction in the intervening areas? Something else? The king cobra is a good swimmer, it is even found in the Andaman Islands apparently, but I doubt it is credible they have swam all the way around the Indian coast to land only and precisely in that small strip in south-west India (also note its absence from Sri Lanka). Is the very first original habitat of the species known? How old is the species? Where are the oldest paleontological remains of the species found? (None of these questions is answered at the article if you're thinking of going there: I've already read it). Thanks. Basemetal 20:11, 8 April 2018 (UTC)

• The most likely explanation is that the king cobra prefers tropical rainforests. That "strip" is rainforest associated with the Western Ghats. Perhaps in the intervening area, before intensive agriculture began, there was a low density of king cobras, enough to allow gene flow. Speciate (talk) 13:58, 9 April 2018 (UTC)

• Agreed. The relevant term is refugium. Matt Deres (talk) 14:06, 9 April 2018 (UTC)

• Cobras are also associated with humans. It's at least possible that humans transported cobras either deliberately or accidentaly, and they then went feral, like Burmese pythons in Florida. -Arch dude (talk) 15:44, 9 April 2018 (UTC)

Tigers in Sri Lanka?

Are there any historical records of tigers ever being found in Sri Lanka? Any paleontological traces there? (This particular Google search is annoyingly interfered with by the well known militant organization). If not, is there any explanation as to why, so close to the Indian mainland? Thanks. Basemetal 20:30, 8 April 2018 (UTC)

Paleontological, yes. (Top tip: adding -Tamil to your search term strips out those unwanted results.) Henry^Flower 20:48, 8 April 2018 (UTC)

"Tigers appear to have arrived in Sri Lanka during a pluvial period during which sea levels were depressed, evidently prior to the last glacial maximum ca. 20,000 years ago". A second extinct big cat from the Late Quaternary of Sri Lanka. Alansplodge (talk) 21:14, 8 April 2018 (UTC)

Thanks to both for the references and the Google search tip. Basemetal 22:43, 8 April 2018 (UTC)