4 ms·

"Number of particles" is a bad metric. One way to formalize this complaint is that this measure is independent of Avagadro's number. In particular, there are

"Number of particles" is a bad metric. One way to formalize this complaint is that this measure is independent of Avagadro's number. In particular, there are many more molecules in a liter of water (~10^24) than there are liters of water in the oceans (~10^21). So if you tag all the water molecules in a single glass of water, fully mix that water in the oceans, and then scoop out another glass from the ocean on the other side of the world, that second glass will contain many tagged molecules. These misleading sorts of statistics also appear when people discuss detection of radiation, e.g., detecting minute radioactive fallout in the US after the Fukushima meltdown.

perfunctory 7y ago
Which part of "freaking plastic is falling out of the sky in fucking ARCTIC" is misleading?
- deleted 7y ago
  [deleted]
- jessriedel 7y ago
  Maybe this will help. Consider the first cup of water that Egyptian pharaoh Tutankhamun drank on his 18th birthday. That water is currently raining down on the Amazon forest. This is not a good argument that we are being overwhelmed by pharaoh water. (Of course, the plastic could be a big problem; this just doesn't show it.)
  - perfunctory 7y ago
    So what in your view would be a better statistic?
    - chrisco255 7y ago
      I would assume Parts Per Million via random sampling or some other relative measurement. And looking at whether that quantity is increasing significantly over time.
    - jessriedel 7y ago
      The fraction of the snow by weight that is plastic (ppm, or whatever), especially with a comparison to the amounts historically and to levels that are known or reasonably suspected of having bad consequences. This, for instance, is how particulate matter is quantified for assessing air quality in urban areas (one of the more harmful and less appreciated environmental damages).
  - azinman2 7y ago
    It doesn’t. The point is the arctic is far away from humans. Yet our generated plastic is falling out of the sky. The importance of this is an ongoing recognition that our plastic is everywhere... no part of the planet is free from the impact of 20th/21st century humanity, and our imprint is forever lasting.
    - jessriedel 7y ago
      Egypt is far away from the Amazon. Yet it's highly misleading (not reasonable) to say "no part of the planet is free from the impacts of Tutankhamun's thirst". Individual atoms of light elements will very often travel around the world on decade-long timescales, regardless of whether they are dangerous or benign.
- SubiculumCode 7y ago
  This is not an appropriate manner of discourse on HN.
  - SubiculumCode 7y ago
    You can down me, but the parent to whom I was responding has since edited their post to remove the language and attitude to which I had objected.
- semi-extrinsic 7y ago
  A much better metric would be to classify the plastic found into major types (polyamides, polyesters, polyethylene, polypropylene, polystyrene, polyurethane, etc) and then to quantify how much (either in mass or weighted also by surface area) there is of each type. All of these factors will have a big impact on how dangerous or safe the microplastics are. In fact, microplastic counts often do not even separate out cellulose based fibers such as Rayon. Then you are talking about a "plastic" which is safe enough to be used for sausage casings, it's just wood pulp which has been broken down and spun into fibers. The research into microplastics is very much in its infancy, like early research into disease transmission talking about the deadly "miasma".
seandougall 7y ago
But TFA is not using "particles" to mean "molecules". It means "pieces of plastic below 5mm in size". Compared to molecules, these are macro-scale objects, and if you mix 10^24 of them into the oceans, that becomes a lot more noticeable than a liter of pharaoh water.
- jessriedel 7y ago
  Right, that's why I criticized "number of particles" as a metric, not the study in general. The point is that "pieces of plastic below 5mm in size" does not have a lower bound, and indeed the journal article discusses pieces that are 300 microns across, overwhelmingly most of which are less than 100 microns across (meaning many thousands of times smaller in mass than suggested by your phrase). This is getting close to metric I already said would be a good one, i.e., ppm, or some other similar metric along with an estimate of the size of harms at this level. For that, you'll have to actually read the paper (please share!) or wait for non-terrible science journalism -- don't hold your breath!

perfunctory 7y ago

Which part of "freaking plastic is falling out of the sky in fucking ARCTIC" is misleading?

deleted 7y ago
[deleted]
jessriedel 7y ago
Maybe this will help. Consider the first cup of water that Egyptian pharaoh Tutankhamun drank on his 18th birthday. That water is currently raining down on the Amazon forest. This is not a good argument that we are being overwhelmed by pharaoh water. (Of course, the plastic could be a big problem; this just doesn't show it.)
- perfunctory 7y ago
  So what in your view would be a better statistic?
  - chrisco255 7y ago
    I would assume Parts Per Million via random sampling or some other relative measurement. And looking at whether that quantity is increasing significantly over time.
  - jessriedel 7y ago
    The fraction of the snow by weight that is plastic (ppm, or whatever), especially with a comparison to the amounts historically and to levels that are known or reasonably suspected of having bad consequences. This, for instance, is how particulate matter is quantified for assessing air quality in urban areas (one of the more harmful and less appreciated environmental damages).
- azinman2 7y ago
  It doesn’t. The point is the arctic is far away from humans. Yet our generated plastic is falling out of the sky. The importance of this is an ongoing recognition that our plastic is everywhere... no part of the planet is free from the impact of 20th/21st century humanity, and our imprint is forever lasting.
  - jessriedel 7y ago
    Egypt is far away from the Amazon. Yet it's highly misleading (not reasonable) to say "no part of the planet is free from the impacts of Tutankhamun's thirst". Individual atoms of light elements will very often travel around the world on decade-long timescales, regardless of whether they are dangerous or benign.
SubiculumCode 7y ago
This is not an appropriate manner of discourse on HN.
- SubiculumCode 7y ago
  You can down me, but the parent to whom I was responding has since edited their post to remove the language and attitude to which I had objected.
semi-extrinsic 7y ago
A much better metric would be to classify the plastic found into major types (polyamides, polyesters, polyethylene, polypropylene, polystyrene, polyurethane, etc) and then to quantify how much (either in mass or weighted also by surface area) there is of each type. All of these factors will have a big impact on how dangerous or safe the microplastics are. In fact, microplastic counts often do not even separate out cellulose based fibers such as Rayon. Then you are talking about a "plastic" which is safe enough to be used for sausage casings, it's just wood pulp which has been broken down and spun into fibers. The research into microplastics is very much in its infancy, like early research into disease transmission talking about the deadly "miasma".

seandougall 7y ago

But TFA is not using "particles" to mean "molecules". It means "pieces of plastic below 5mm in size". Compared to molecules, these are macro-scale objects, and if you mix 10^24 of them into the oceans, that becomes a lot more noticeable than a liter of pharaoh water.

jessriedel 7y ago
Right, that's why I criticized "number of particles" as a metric, not the study in general. The point is that "pieces of plastic below 5mm in size" does not have a lower bound, and indeed the journal article discusses pieces that are 300 microns across, overwhelmingly most of which are less than 100 microns across (meaning many thousands of times smaller in mass than suggested by your phrase). This is getting close to metric I already said would be a good one, i.e., ppm, or some other similar metric along with an estimate of the size of harms at this level. For that, you'll have to actually read the paper (please share!) or wait for non-terrible science journalism -- don't hold your breath!