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The effects of carbon dioxide (CO2) in Earth’s atmosphere are well documented and well understood: as a greenhouse gas, it traps heat from the Sun and contributes to rising temperatures. But CO2 is also making life less comfortable beneath the waves by contributing to rising ocean acidity, which can impact marine life and fisheries that support a $183 million industry in the U.S. Now new research shows that runoff from farms and discharge from sewers is adding CO2 to waterways by feeding algal blooms.

 

Burning fossil fuels for heat, electricity and transportation is one way CO2 gets into the air and water. In the new Environmental Science & Technology paper, William G. Sunda and Wei-Jun Cai explain that since the Industrial Revolution in the 18th and 19th centuries, the amount of carbon dioxide in the atmosphere has increased 40 percent. The oceans absorb about a third of that, which means that levels of CO2 in the ocean have been rising apace.

 

When CO2 dissolves in water, it reacts with water to form a number of related compounds, including carbonic acid. This makes ocean water more acidic, which can kill shellfish, deplete food stocks for larger predators, force fish populations to migrate and make it harder for corals to grow.

 

Another source of CO2 in the oceans is algae, which range from giant kelp and seaweed to microscopic versions that float with the currents. When there is an influx of nutrients, the latter can explode in number, forming so-called algal blooms. These population booms can form a green, yellow or brown scum on the water’s surface, with hundreds or thousands of algae in each teaspoon of water. Infamous red tides are one example. Fertilizer running off fields and organic matter discharged from sewers enter major waterways and end up in the oceans, where blooms can form.

 

These blooms quickly devour all the available oxygen and can kill off other ocean life, as has happened in the infamous “dead zone” at the mouth of the Mississippi. They also produce large amounts of CO2, contributing to the growing acidification problem.

 

Sunda and Cai took all this into account to build a computer model of how ocean acidification is likely to proceed. Another piece of the puzzle that they added into their model: ocean acidity is also affected by temperature, which is changing as more CO2 enters the atmosphere. Between CO2 from the atmosphere and algal blooms, the authors’ model predicts that the oceans will get increasingly acidic.

 

The effects might be greatest for fisheries in places like the Gulf of Mexico and the Baltic Sea because of the large amount of nutrient input from coastal sources in those areas. The report singles out clams, oysters, scallops and mussels as populations that may be the most heavily impacted.

 

What other effects of ocean acidification concern you?

 

“Eutrophication Induced CO2Acidification of Subsurface Coastal Waters: Interactive Effects of Temperature, Salinity, and Atmospheric PCO2Environmental Science & Technology

 

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Credit: National Oceanic and Atmospheric Administration

This is a story about how less can be more. It’s rather rare to come across such examples in these United States of America, where so many people believe more is usually better. Take the Big Gulp, or the other “super-sized” soft drinks or the large fries. Of course, there are instances when people agree that less is better –– less weight around the mid-section, for example.


And this story does relate to something that is healthful. We’re talking about microgreens, those little greens on top of your soup or salad or inside your gourmet sandwich. Amazingly, they have more concentrated vitamins and nutrients than full-sized versions, researchers report.

Generally, these are seedlings of spinach, lettuce, red cabbage and other vegetables, about 1-3 inches tall, picked within two weeks of germination. The microgreens have been a popular item in high-end markets and restaurants, but here is a slight problem: Microgreens are rather expensive. They cost from $30-$50 a pound in stores, usually sold in
4–8 oz. bunches or in 1-lb. containers. The good news is that some home gardeners are producing their own microgreens which, like the full-size veggies, are cheaper to grow than to buy in stores.


Overall, the mini-plants improve the color, texture and flavor of everything from soup to salads and sandwiches and other foods. Until recently, however, no scientists had compared their nutrients to the full-grown veggies.

Qin Wang, Gene E. Lester and the rest of their research team are the first to study vitamins and other chemical compounds that occur naturally in these mini-plants. They looked at 25 varieties of microgreens and found that they generally have higher concentrations of healthful vitamins and carotenoids (powerful antioxidants that may help prevent cancer and heart disease) than full-sized versions.

The scientists reported in ACS’ Journal of Agricultural and Food Chemistry that they also discovered wide variations in nutrient levels among the plants tested in the study. Red cabbage microgreens, for example, had the highest concentration of vitamin C, while green daikon radish microgreens had the most vitamin E. Interestingly, they also found that microgreens grown under lights had a higher nutritional content. (The researchers will formally report these data later.)

 

“Assessment of Vitamin and Carotenoid Concentrations of Emerging Food Products: Edible Microgreens,” Journal of Agricultural and Food Chemistry

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Credit: iStockphoto/Thinkstock

Sure, smoking can cause lung cancer, but until I saw this paper in ACS’ Journal of Proteome Research (JPR), I had no idea it also can weaken bones. Apparently, I’m late to the game, as it’s been almost 20 years since scientists first figured that out.

 

Smoking is a risk factor for osteoporosis, a condition in which bones get thin and become less dense. That makes the bones brittle, and they can break easily (think of broken hips among the elderly). It’s often associated with a hump at the base of the neck or a stooped posture that’s caused by the spine bones, or vertebrae, weakening. People with the condition also lose height, becoming up to six inches shorter over time. The disease is more common in women than men, with about 1 in 5 of U.S. women developing the condition after age 50. It’s a major cause of disability among older people.

 

Of course, aside from osteoporosis, smoking is better known for increasing the risks of developing heart disease, stroke, emphysema and many cancers, including bladder, lung and pancreatic cancer.

 

But how could smoking cause osteoporosis?


In the JPR paper, Gary Guishan Xiao and colleagues point out that previous studies suggested that toxins in cigarette smoke weakened bones by affecting the activity of osteoblasts, cells that build new bone, and osteoclasts, which break down, old bone. But is one of these cell types more affected? How exactly does smoking make bones weak and brittle?


To shed light on how cigarette smoking weakens bones, the scientists analyzed differences in genetic activity in bone marrow cells of mice exposed to cigarette smoke and those not exposed to smoke. They also examined cells from human smokers and non-smokers.


They discovered that human smokers produce unusually large amounts of two proteins that trigger the production of bone-resorbing osteoclasts compared to non-smokers. The experiments with laboratory mice confirmed the finding.


(The researchers acknowledged funding from the Cancer and Smoking Related Disease Research Program and the Nebraska Tobacco Settlement Biomedical Research Program.)


“Smoke-Induced Signal Molecules in Bone Marrow Cells from Altered Low-Density Lipoprotein Receptor-Related Protein 5 Mice,” Journal of Proteome Research

 

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Credit: iStock