Toxic Chemicals from Peeing in the Pool

Toxic Chemicals from Peeing in the Pool Lets face it. Its not just babies who pee in the pool! Is that guy on the other side of the pool trying to look cool or is he concentrating on a little public urination? You dont know, because there isnt a chemical you can put in the pool as a urine indicator that wouldnt be toxic or respond to a whole host of other fluids. The Water Quality and Health Council conducted a survey that revealed one in five Americans admit to urinating in the pool. So, unless that pool was filled an hour ago, youre swimming in pee. But, urine doesnt just sit there in the water or harmlessly disperse. It reacts with chemical treatments in the water. For the same reason you dont want to rinse out a really nasty kitty litter box with bleach, you might not want to inhale too deeply in a pool full of people. The chemical reactions form two particularly nasty compounds: cyanogen chloride (CNCl) and trichloramine (NCl3). In high concentrations, these are chemical warfare agents. In the minute quantities produced in a pool, you wont die, but youre not doing your lungs any favors, not to mention your nervous and circulatory systems. Chlorine treatments, in particular, react with uric acid from urine to form toxic chemicals. The pool treatments themselves often aggravate respiratory and other health problems, since chlorine is (you guessed it) a toxic chemical agent. Its really not something to worry about, as researchers have found levels of the chemicals are lower than the World Health Organization (WHO) limits for public drinking water. However, if it bothers you, you have a few options. Swim in an outdoor pool rather than an indoor one, so vapors become diluted in the air rather than trapped in an enclosed space. Switch to a different pool disinfection method. Or, you can build your very own private pool and resist the urge to pee in it. Reference:  Volatile Disinfection Byproducts Resulting from Chlorination of Uric Acid: Implications for Swimming Pools,  Lushi Lian, Yue E, Jing Li, and Ernest R. Blatchley , III,  Environ. Sci. Technol.,  2014,  48  (6), pp 3210–3217.

The First Reptiles and Their Evolution

The First Reptiles and Their Evolution We all know how the old story goes: Fish evolved into tetrapods, tetrapods evolved into amphibians, and amphibians evolved into reptiles. Its a gross oversimplification, of course- for example, fish, tetrapods, amphibians,  and reptiles all coexisted with each other for tens of millions of years- but itll do for our purposes. And for many fans of prehistoric life, the last link in this chain is the most important, since it was the dinosaurs, pterosaurs and marine reptiles of the Mesozoic Era that all descended from ancestral reptiles. Before we proceed any further, though, we need to define what the word reptile means. As far as biologists are concerned, the single defining characteristic of reptiles is that they lay hard-shelled eggs on dry land (as opposed to amphibians, which are constrained to lay their softer, more permeable eggs in water). Secondarily, compared to amphibians, reptiles have armored or scaly skin (which protects them from dehydration in the open air); larger, more muscular legs; slightly bigger brains; and lung-powered respiration (though no diaphragms, which were a later evolutionary development). Depending on how strictly you define the term, there are two prime candidates for the first-ever reptile. The first is the early Carboniferous (about 350 million years ago) Westlothiana, from Europe, which laid leathery eggs but otherwise had a distinctly amphibian anatomy, especially pertaining to its wrists and skull. The second (and more widely accepted) candidate is Hylonomus, which lived about 35 million years after Westlothiana and resembled the kind of small, skittery lizard you run across all the time in modern pet stores. This is all simple enough, as far as it goes, but once you get past Westlothiana and Hylonomus, the story of reptile evolution gets much more complicated. Three distinct reptilian families appeared during the course of the Carboniferous and Permian periods. Anapsids like Hylonomus had solid skulls, which provided little latitude for the attachment of robust jaw muscles; the skulls of synapsids sported single holes on either side and the skulls of diapsids had two holes on both the left and right sides. These lighter skulls, with their multiple attachment points, proved to be a good template for later evolutionary adaptations. Why is this important? Well, anapsid, synapsid and diapsid reptiles pursued very different paths toward the start of the Mesozoic Era. Today, the only living relatives of the anapsids are turtles and tortoises (though the exact nature of this relationship is hotly disputed by paleontologists). The synapsids spawned one extinct reptilian line, the pelycosaurs (the most famous example of which was Dimetrodon), and another line, the therapsids, evolved into the first mammals of the Triassic period. Finally, the diapsids evolved into the first archosaurs, which then split off into dinosaurs, pterosaurs, crocodiles, and (probably) marine reptiles like plesiosaurs and ichthyosaurs. Lifestyles of the First Reptiles But were getting ahead of ourselves; much of this information is discussed in  Before the Dinosaurs - Pelycosaurs, Archosaurs, and Therapsids. What were interested in here is the obscure group of lizard-like reptiles that succeeded Hylonomus and preceded these better-known (and much larger) beasts. Its not that solid evidence is lacking; plenty of obscure reptiles have been discovered in Permian and Carboniferous fossil beds, especially in Europe. Its that most of these reptiles look so similar that it can be an eye-rolling exercise to attempt to distinguish between them. The exact classification of these animals is a matter of continuing debate, but heres our attempt to cut through the froth: Captorhinids, exemplified by Captorhinus and Labidosaurus, are the most basal, or primitive, reptile family yet identified, only recently evolved from amphibian ancestors like Diadectes and Seymouria. As far as paleontologists can tell, these anapsid reptiles went on to spawn both synapsid therapsids and diapsid archosaurs. Procolophonians were plant-eating anapsid reptiles that (as mentioned above) may or may not have been ancestral to modern turtles and tortoises; among the better-known genera are Owenetta and Procolophon. Pareiasaurids were much larger anapsid reptiles that counted among the biggest land animals of the Permian period, the two best-known genera being Pareiasaurus and Scutosaurus. Over the course of their reign, the pareiasaurs evolved elaborate armor, which still didnt prevent them from going extinct 250 million years ago! Millerettids were small, lizardy-looking reptiles that subsisted on insects, and also went extinct at the end of the Permian period. The two most well-known terrestrial milleretids were Eunotosaurus and Milleretta; an ocean-dwelling variant, Mesosaurus, was one of the first reptiles to de-evolve to a marine lifestyle. Finally, no discussion of ancient reptiles would be complete without a shout-out to the flying diapsids, a family of small Triassic reptiles that evolved butterfly-like wings and glided from tree to tree. True one-offs, and well out of the mainstream of diapsid evolution, the likes of Longisquama and Hypuronector must have been a sight to see as they fluttered high overhead. These reptiles were closely related to another obscure diapsid branch, the tiny monkey lizards like Megalancosaurus and Drepanosaurus that also lived high up in trees, but lacked the ability to fly.