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The La B()ea(ch) Tar Pits

Those of you familiar with the area might get my reference to the natural La Brea Tar Pits next to the LAC Museum of Art. It turns out, the tar doesn’t just naturally occur on land. It’s also on the beaches. I was not a happy beach-goer when I found out about this. Tar contains carcinogens! That’s not really something I want to be running around in!

Seventeen Techers were cleaning a local beach, Manhattan Beach. The trip was sponsored by the Caltech Y, ESW (Engineers for a Susatainable World), and by the work study program. We headed to the beach bright and early and stayed there until about three.

Why do so many smokers leave their cigarette buts lying around? That’s just not okay. Then there were also the big pieces of trash, and leaving those behind almost can’t be an accident. At the beginning of the year, Net Impact, one of the clubs I’ve written about, screened a movie about the plastic in the Pacific and had the director come out. The director told us a story about rubber duckies travelling from China to the US that had fallen off of their container ship – and ended up just about everywhere oceans can take them (https://www.rubaduck.com/news/rubber_duck_news-200302-duckies_around_the_world.htm). The trash people don’t throw away on the oceans will pollute – certainly by the next high tide, if no one picksit up! That makes me ANGRY!

On the bright side, we didn’t actually find a ton of trash – so there’s got to be a substantial number of people who pickup up after themselves as well! [and there’s a group that cleans this particular beach on a semi-regular basis.] And, to highlight the positive, there was a group of nice bikers that stopped to thanks us 🙂

The tar bothered me most, though. It wasn’t that there was so much tar than trash, but that I know where the trash is coming from and I know whose fault it is. Further, tar is a carcinogen, and while letting a plastic bottle disinigrate at the beach isn’t healthy, I don’t think it has quite the same health effects. The tar was found in small chunks in that line of seaweed and shells at the high-tide marker (if you’ve been at a beach, you know what area I mean, right?):

We could even smell the tar in our trash bags — there was so much of it! The little tar paddies would melt when exposed to the sun or to our gloves. A lot of the paddies had shells or dead crabs stuck in them. When I asked a lifeguard about it, he said it comes from the ships (mostly from those carrying oil) and from natural oil seeps in the ocean. I asked him what was being done about it, and apparently, nothing. I noticed almost as soon as I came to Caltech that there were signs like everywhere warning people that parking garages or other places had been shown to have "carcinogens known to the State of California" at every entrance [this is law in CA; I’ve seen similar signs in NH, but not nearly as many in as varied places!]. I’ve been doing some research on this tar-on-CA-beaches thing since returning from the trip yesterday, and tar definitely has carcinogens too (https://www.archeolog-home.com/rubrique,asphalt,1276347.html)! Why aren’t there warning signs around the beaches? I’ve been finding a lot of "locals" writing about this, and in particular, about how suprised tourists usually are to find tar on the beaches. Yeah, I was. Which is why I’ve been looking into it, and frankly, until people (like our awesome profs here at Tech) showed people how shocking the smog in LA was, not much was done to change it. If the source of most of this tar is from oil leaks, we need to prevent these leaks.

That was the source the lifeguard gave us, but it doesn’t seem to be the actual source according to the USGS. According to them (https://soundwaves.usgs.gov/2008/04/fieldwork2.htmland https://soundwaves.usgs.gov/2007/05/research2.html), the majority of the tar comes from the natural oil seeps in the ocean off the coast of CA. These are from the Miocene Monterey Formation, an oil-bearing rock the source of many natural oil /tar seeps along the CA coast. The articles go on to conclude that the chemical fingerprints of these tar residues were shown to be from natural tar seeps.

Two more interesting articles are https://walrus.wr.usgs.gov/research/projects/oilandgasseep.htmland https://walrus.wr.usgs.gov/seeps/where.html.

One question, and if any of you know more about this than I do, I’d love to hear what you know! The article also says that the Miocene Monterey Formation is ALSO the source of the "oil produced by CA’s onshore and offshore oil wells." [And it totally makes sense that the largestnatural seeps would also be the mined ones, since theyhave large resevoirsofoils and tar.] But, if oil and tar are both seeping out of a natural formation, and being gathred commerically and then transported via ships, how do their chemical fingerprints differ enough to be able to tell them apart?

The lifeguard also told us that most people remove the tar on their skin with gasoline. I googled gasoline, and Wikipedia says that "It consists mostly of aliphatic hydrocarbons obtained by the fractional distillation of petroleum, enhanced with isooctane or the aromatic hydrocarbons toluene and benzene to increase its octane rating." I had to use benzene for some of my SURF syntheses. My mentors made sure to warn me about the danger of benzene – it is a known carcinogen. DON’T use gasoline to get the tar off of your feet (USGS confirms this :))! Water, soap, and scrubbing worked fine. [Granted, I’m sure the tar would be more soluable in gasoline than in water, but I’d rather use a non-carcinogenic material and scrub a little more!!].

Enough about the tar 🙂 The rest of our trip was really fun. During our lunch, a bunch of us went into the ocean – it was really warm! We tried our luck body-boarding, with moderate sucess. The waves at Manhattan are definitely better than those I have seen at Santa Monica (finally, some of those famous CA waves!). It was super-fun!! And of course, I managed to get sun-burned once again [it was cloudy!! where does this CA sun hide?]. I hope you had fun reading about our trip to the beach / my trip to google :)!

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