A Breath of Fresh Air

If you like fresh air, you're probably a big fan of the Clean Air Act and its amendments. While the air in many places is far from ideal, prior to federal legislation it was downright deadly in American cities. A clear gray sky on a summer's day in Philadelphia is a little off-putting, but it beats a smothering fog in the valleys outside Pittsburgh. After the deadly Donora smog in 1948 killed 20 and sickened thousands of others. Federal investigators were asked to come in, and determined that air pollution was in fact the killer, among other factors.

Donora smog, 1948 (Smithsonian)

The government prefers to take baby steps when implementing positive change, rather than jumping in feet first, and tackling air pollution is no exception. The first step came in 1955 with the Air Pollution Control Act, which provided funding for research and led to the Clean Air Act of 1963 and Air Quality Act of 1967. These provided the first air quality monitoring.

Pittsburgh in the 1940s (Citylab)

The Clean Air Act of 1970 was a major step forward. It developed limits on pollution and expanded federal enforcement powers. Among the controls included were auto emissions. States were mandated to implement plans to reduce pollution.
The Amendments of 1990 aimed to reduce air pollution linked to acid rain and ozone depletion.
Looking at a picture of the summer sky over Los Angeles, it might be hard to believe the Clean Air Act is working. However, the number of ugly sky days is lower than prior to enactment. Air quality monitors in California frequently show poor quality, and geography is partly to blame. Ocean breezes carry pollution as far as the mountains, where it gets stuck and sometimes builds up for days.

Los Angeles skyline (LAist)

Acid rain has been reduced as a result on the 1990 amendments. pH testing has shown freshwater pH levels in many areas have risen closer to neutral 7. Pure water is neutral, but in nature, water is rarely pure. Pristine rain is slightly acidic because of carbon dioxide in the atmosphere forming carbonic acid. However, the lowered pH in rivers and lakes nationwide was far lower than caused by carbonic acid. Targets of the 1990 amendments were nitrogen oxides (NOx) and sulfur dioxide (SO2). Emissions have been greatly reduced over the last 30 years, and ecosystems are continuing to slowly recover.

Visuals of higher pH meaning less acidic water samples
(National Atmospheric Deposition Program)

Information this week comes the EPA (Clean Air Act overview), Smithsonian Magazine (Donora), and more EPA (acid rain). For a great visual on showing higher pH and lower NOx and SO2, check out the National Atmospheric Deposition Program.

EPA: https://www.epa.gov/clean-air-act-overview/evolution-clean-air-act
Smithsonian: https://www.smithsonianmag.com/history/deadly-donora-smog-1948-spurred-environmental-protection-have-we-forgotten-lesson-180970533/
EPA: https://www.epa.gov/airmarkets/acid-rain-program
nm1 LAist: https://laist.com/2018/10/30/why_las_smog_has_been_extra_smoggy.php
nm2 Citylab: https://www.citylab.com/design/2012/06/what-pittsburgh-looked-when-it-decided-it-had-pollution-problem/2185/
nm3 Smithsonian
nm4 National Atmospheric Deposition Program http://nadp.slh.wisc.edu/data/animaps.aspx

Species of the Month

With Thanksgiving just a week away, once again we turn our attention to the dinner plate. In years past, November's Species of the Month has featured the wild turkey, venison, and clams that were likely present at the first Thanksgiving. This year, we look at a staple of the modern celebration, the North American cranberry.

Whole berry cranberries (UWLC)

Scientific name: Vaccinium macrocarpon

Kingdom: Plantae (plants)

Class: Magnoliopsida (dicots)
Order: Ericales (heath)

Cranberries on the shrub (UWLC)

Range: US west coast, northeast US and Great Lakes areas
Habitat: Bogs with acidic soil
Diet: Water and sunlight
Predators: Bears, rodents, birds, deer, humans
Conservation Status: Listed as endangered in Illinois and threatened in Tennessee

Cranberry bog

Other facts: Cranberries grow in freshwater peat bogs. They are grown commercially for use in food products. The best use is the canned jellied cranberry. Cranberry plants are useful as a food source for animals. Birds, bear, and rodents eat the berry, while deer browse the shrub. Birds and rodents also use the stems for nesting material. Birds may also build a nest in the shrub. Cranberries also form a symbiotic relationship with fungi, giving up sugar in exchange for access to soil nutrients. Cranberries can survive being submerged for long periods, and even being kept on ice over the winter.

Cranberry flower (Cape Cod Cranberry Growers)

This week's information comes from Cape Cod Cranberry Growers Association, USDA PLANTS, and University of Wisconsin- La Crosse. Pictures, except the flower, are also from University of Wisconsin- La Crosse.

Transit of Mercury

Frequently, we observe solar and lunar eclipses here on our blue marble we call Earth. Solar eclipses are when the moon passes in front of the sun. Lunar eclipses are when Earth cuts between the sun and moon, with the moon covered in our shadow. Less commonly observed are planetary transits. Because we live on the third rock from the sun, we only get to see Mercury and Venus pass in front of it. Because orbits wobble and planes aren't aligned, this is something that is only seen a few times per century.

Transit of Mercury as seen with the unaided eye

Mercury transited the sun on November 11. Because the sun is so bright and Mercury is so small, a telescope with solar filter is a requirement to witness the event. I took a field trip to Philadelphia's Franklin Institute to see it for myself with their telescope. Because seeing Mercury normally requires a clear horizon at sunrise or sunset, most folks don't get to see it. This was my first time, and now I've finally seen all six naked eye planets- I included Earth, which I see every day.

Franklin Institute's telescope with solar filter

I got a shot of Mercury being live-streamed on the big screen

Sadly, I wasn't able to get my own pictures of Mercury, but I did get pictures. NASA was live-streaming and has a video up on their Youtube page. If you want to see a Mercury transit live and in person, you'll have to wait until 2032. You'll need to be in Africa, eastern Europe, or western Russia to see it. Otherwise, the next transit here in the states won't be until 2049. But if you think that's bad, the next transit of Venus won't happen until 2117.

NASA posted this picture of a prior transit on their Facebook page.
The little black spot on the bottom is Mercury. The one on
the top is a sunspot.

Changing Leaves

Fall is in full swing. The sun keeps the air warm, but it's chilly in the shade. Honking geese fly overhead and crickets chirp throughout the lengthening nights. Dried leaves swirls about in the breeze, while those still in the trees for a riot of color. What is going on inside the tree that causes the color change?
Trees are getting ready for a long winter's nap. Like animals going into hibernation, everything is slowing down. Trees have been gorging themselves on sunlight all summer, and now their metabolism is slowing down. The chlorophyll is breaking down and water uptake is stopping. Chlorophyll absorbs all wavelengths of light except green, which is reflected back to us. Without chlorophyll, we see other chemicals in the leaf.

A yellow sugar maple catches the late morning sun

The yellow leaf of a sugar maple

Xanthophyll colors the leaves of aspens, birches, and beeches a bright yellow. It's also found in corn.  Red and purple in red maples and scarlet oaks comes from anthocyanin, which is produced when the chlorophyll stops and the leaf metabolizes extra sugars. Carotene, the same as what you find in a carrot, gives trees like sugar maple and sassafras their orange leaves. Orange can also come from a leaf that is showing both xanthophyll and anthocyanin. Brown, such as in oaks, comes from tannins. Carotene and Xanthophyll are present all year in the leaves, but are overshadowed by chlorophyll.

Another sugar maple, this one decked out in red

This red sugar maple leaf fell of a Canadian flag

The brilliance of each color, as well as the amount of colors relative to each other, are dependent on the weather. If fall is sunny and dry, trees will produce more anthocyanin. Trees will be a more brilliant red. Other years, trees won't produce as much or even none at all and nearly all leaves will change to yellow.
But of course, each tree is an individual so it may change well before its neighbor or have different or more vibrant colors, even among the same species. I've seen red maples that look like traffic lights with red, yellow, and green leaves on the same tree. I've even seen multi-colored leaves.

Brown oak leaf, rich in tannin

Yet another sugar maple, this time in orange

Get out there and enjoy some biochemistry in action before it's too late! The leaves have been great this year, peaking in my area this week and next. Up north you may be past peak, and down south it's on its way! This week's information comes from SUNY College of Environmental Science and Forestry and Montana Natural History Center.

Yellow and brown hickories and oaks basking in late
afternoon sunshine

Species of the Month

With Halloween right around the corner, October's Species of the Month is another creepy crawly. You might be afraid of spiders or bats, but no one wants to see a rat in the house. This month we profile the ubiquitous black rat (AKA house rat, AKA roof rat, AKA ship rat), destroyer of crops, chewer of things, and spreader of plague. 

Halloween rats from Pintrest

Scientific name: Rattus rattus
Kingdom: Animalia (animals)

Class:  Mammalia (mammals)
Order: Rodentia (rodents) 

Range: Worldwide; native to India and Southeast Asia
Habitat: Almost anywhere
Lifespan: Average 1 year, up to 4 years

Black rat (Inventaire National du Patrimoine Naturel)

Diet: Omnivorous, but mainly plant-based (fruits, grains, seeds)
Predators: House cats, birds of prey, foxes, coyotes
Conservation Status: No special protection
Other facts: The black rat was spread around the world by travelers. They are also called ship rats because if their affinity for sailing to new homes on distant shores. The moniker roof rat comes from their climbing skills. They are an invasive pest everywhere outside of their native range, ruining food stores by soiling what they don't consume. They were a disease vector during the plague outbreaks of Medieval Europe, carrying fleas that hosted the virus. While plague is not as serious a threat as it was in the Dark Ages, the fleas on a rat can still spread other diseases to humans and livestock. A similar species, the Norway rat, is just as widespread and will kill the smaller black rat. Despite the headaches caused by both rats, they are important links in the food chain now that they've become established. Hawks, owls, coyotes, and foxes are among their main predators.

Black rat (Australian Environmental Pest Managers Association)

This month's information comes from the University of Michigan's Animal Diversity Web once again.

nm1: 
nm2: https://www.aepma.com.au/PestDetail/96/Black%20Rat