From Cloud Seeds to Lightning-Made Fertilizer

It’s counter-intuitive but true that water vapor has a hard time turning into water droplets without a solid or liquid surface to act as a seed.  Once liquified, water droplets can remain in a supercooled state below the freezing point in the absence of crystallization surfaces. The correct term for this “seed” is a cloud condensation nucleus, unfortunately creating the need for yet another abbreviation (CCN).

In the 1960s and 1970s James Lovelock proposed that aerosol particles which act as cloud-condensation nuclei (CCN) in the marine atmosphere are principally, perhaps almost exclusively, non sea-salt SO42- particles derived from the breakdown and oxidation of an organic compound (dimethyl sulphonio propionate) that algae used to remain isotonic with their saline environment.

The “perhaps almost exclusively” part was unfortunately never substantiated by evidence. A recent review study revealed that dust, sea salt, soot, biological particles such as pollen along with secondary organic aerosols—Lovelock’s non sea-salt SO42- —can all act as CCN. In fact, the ability of all this material to act as cloud seed depends far less on their chemical composition and more on aerosol particle size.

Another important conclusion from the review of the literature involves the impact of human activity on CCN:

Model calculations and observations in remote continental regions consistently suggest that CCN concentrations over the pristine continents were similar to those now prevailing over the remote oceans, suggesting that human activities have modified cloud microphysics more than what is reflected in conventional wisdom.

Lightning photographed by the author on July 27 in Montreal.
Lightning photographed by the author on July 27 in Montreal.

Once the droplets and ice crystals do form, rising droplets in cumulonimbus clouds collide with ice crystals. Electrons are transferred leading to the major static responsible for lightning.

The bolts of lightning, as this Nova video http://www.pbslearningmedia.org/resource/nves.sci.earth.nitrate/lightning-produces-nitrates/ explains are not very thick but are energetic enough to melt sand and break nitrogen’s triple bond. The free nitrogen atoms then attack air’s other main component, oxygen, to form nitrate, which is an important fertilizer.

Although Lovelock’s Gaia hypothesis is not backed up by observations—the algae with its byproduct aren’t single-handedly bioregulating wind patterns and eventual distribution of nutrients in the sea—there is in reality an astounding interplay of geology, biology and climate on our planet. Even in the absence of man, dust from dry lake beds and volcanoes, pollen and organics from land and microscopic sea organisms, respectively, make condensation possible, which then leads to lightning. Finally the latter forms nitrates which fertilize soil and seas,  finding their way into the proteins and genetic material of life.

Aside from highlighting the planet’s interconnections and revealing that divisions between science disciplines are often academic, the Gaia has important philosophical implications.

In Lovelock’s view humanity is peripheral, though dangerous, to the life systems of the planet. Our anthropocentric concern is to preserve the earth as we want it. Lovelock believes that ideas of stewardship of the planet are absurd and dangerous “hubris“: “We’ll never know enough…….. The answer is ’hands off”….Micro-organisms drive the system and we cannot influence them.

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Why Lawn Grass Is Not Green

From an aesthetic or ecological point of view, a lawn is preferable over concrete, stone and asphalt. The latter trio absorb light energy but then slowly re-radiate as infrared, adding to the heat-island effect of urban areas. Grass instead keeps things cooler. While growing rapidly and absorbing carbon dioxide and water, it invests a fair amount of light energy into the bonds of cellulose. If mulched when mowed, its carbon conditions the soil.

But what’s wrong with grass in the city? Most lawns in temperate areas of Europe and North America consist of Kentucky bluegrass. To be kept in a juvenile state and to be given a competitive edge over plants of the C4 variety, lawns leave behind a deep ecological footprint: they have to be watered, fertilized, mowed and weeded.

Few take measures to conserve water and electricity by relying only on rain and using a manual reel mower. Only a minority use compost instead of synthesized fertilizer, which is energy-intensive and which can lead to runoff and eutrophication. And in most neighborhoods, people don’t get on their hands and knees to remove plantain, dandelion and other “weeds”.  Instead they reach for herbicides, some of which contain glyphosate, a probable carcinogen.

We can learn from history, as researched by the authors of this Calgary website. The popularity of lawns is historically rooted in status—they first became fashionable among 17th century English and French aristocracy who were the only ones financially capable of hiring others to maintain the luxury. Kentucky bluegrass and Bermuda grass became adopted only in the 19th century when people did not realize the shortcomings of  “monoculture”.

Some low-growing oregano and black medic adding a variety to my lawn.
Some low-growing oregano and black medic adding a variety to my lawn.

Why can’t lawns be an example of biodiversity and showcase a variety of low-growing, low-maintenance plants? Many plants that normally grow taller will succumb to the selective pressure of an electric or manual mower and will even flower when only a few centimeters tall. Legumes such as black medic, white and red clover fix nitrogen from the air and require need little or no fertilizer. Thyme and oregano, which generally prefer well-drained soils and are ideal for sloped terrain, need less water than grass. Young leaves of maligned dandelion actually make a good addition to salads. Species of stitchwort and wild violets produce small but subtle flowers.

Ralph Waldo Emerson lived at a time when lawns became popular. Yet he realized that “a weed is a plant whose virtue is not yet known”, a statement quite consistent with his transcendentalism. Our surroundings could bring out our better nature. Ecological lawns could help urbanites become more environmentally responsible.

Birdsfoot trefoil, vetch & red clover abound near  St.Laurent's  duBoisé library, one designed with  ecology in mind.
Birdsfoot trefoil, vetch & red clover abound near St.Laurent’s duBoisé library, one designed with ecology in mind.

Nitrates and Nitrites in Food and Vegetables

Capture33Why not have a salad for breakfast, especially when it contains Mom and Dad’s home-grown lettuce? Because they either use no fertilizer or in the odd year composted manure, it’s lower in nitrates ( I measured about 250 ppm, relatively low for lettuce). Fresh manure can contaminate it with both nitrates and bacteria, while most synthetic fertilizer will also increase the concentration of the ion and more significantly.

If the recommended amount of inorganic fertilizer (200 kg·N·ha−1) is used as a standard of comparison, lettuce augmented with organic fertilizers (200 kg·N·ha−1) have significantly longer and wider leaves, higher shoot, and lower concentrations of nitrate.  ncbi.nlm.nih.gov/pmc/articles/PMC4025000/

The amount of nitrate from synthetic Other vegetables and fruits known to be high in nitrates include spinach and strawberries. Here’s more on why nitrates can be harmful and what foods contain them.

  1. Why worry about nitrates (NO3) and nitrites NO2?

Here’s the latest health effect summary(italicized) from the Environmental Protection Agency

A)                 Excessive levels of nitrate in drinking water have caused serious illness and sometimes death. The serious illness in infants is due to the conversion of nitrate to nitrite by the body, which can interfere with the oxygen-carrying capacity of the child’s blood. This can be an acute condition in which health deteriorates rapidly over a period of days. Symptoms include shortness of breath and blueness of the skin.

One author (Martijn Katan ) who is a nutritionist argued here (http://ajcn.nutrition.org/content/90/1/11.full#ref-3) that what’s being described above (methemoglobinemia ) is actually caused by bacterial contamination and subsequent production of nitrogen monoxide. But that was one conclusion from an experiment in the 1950s. Meanwhile, reputable medical sources (such as http://www.nlm.nih.gov/medlineplus/ency/article/000562.htm) point out that nitrites and nitrates can cause methemoglobinemia , and it can also be brought about by a host of other compounds according to several sources that show up in Google Scholar under “causes of  methemoglobinemia”.

B)                 Drinking water levels which are considered “safe” for short-term exposures: For a 10-kg (22 lb.) child consuming 1 liter of water per day, a ten-day exposure to 10 mg/L total nitrate/nitrite.

C)                  Chronic: Effects of chronic exposure to high levels of nitrate/nitrite include diuresis, increased starchy deposits and hemorrhaging of the spleen.

D)        Cancer: There is inadequate evidence to state whether or not nitrates or nitrites have the potential to cause cancer from lifetime exposures in drinking water.

So it is still a possibility given that their presence and impact can combine with that of known carcinogens in the environment. Nitrates and nitrites are not themselves carcinogenic but they can form cancer-causing nitrosamines in the gut.

  1. What foods are sources of nitrates and nitrites?

Bacon particularly along with cold cuts and hot dogs have nitrites added to them either in the form of sodium nitrite or celery salt. But erythorbic and ascorbic acids are also added to prevent nitrosamine formation. Meanwhile spinach, especially, and lettuce can also have concentrations of nitrate that can be as high as those of bacon. But it depends on how they’re grown! If they are grown with composted manure, legume-enriched soil or with no fertilizer at all, these vegetables will have safe levels of nitrates. What elevates their concentration is liquid synthetic nitrates, some other nitrogen fertilizers and fresh manure, especially that of chickens. It should also be noted that outer leaves of lettuce have more nitrates than the inner leaves, since they have more time to concentrate them.

3. What happens to nitrites in processed meats?

Nitrites from cold cuts that have been rendered red by the addition of nitrites (hot dogs that  are made from byproducts are pale in color without nitrite) can form nitrosamines . Certain antioxidants added along with nitrites are supposed to prevent this. It works in most cases except in fried bacon, cured meats and salami, which contain between 2 and 11 ppb of nitrosamines(specifically, N-nitrosodimethylamine). Interestingly the nitrosamines in raw fish are volatile and do not show up in the analyses of cooked fish.

4. Can Excess Nitrates from Fruits and vegetables End Up As Nitrosamines?

Salivary glands and microbes in saliva are capable of converting some nitrates to nitrites, which subsequently, under the stomach’s acidic conditions can end up as nitrosamines. Some nitrites end up as nitrogen monoxide, which can have beneficial effects.

Another factor to consider is the serving size of cured meats and salami relative to that of a salad. Four slices of a cold cut has twice the mass of a serving of lettuce. So even if the compared foods contain an equal concentration of nitrites/nitrates, eating treated meat would expose you to twice the amount. Add lettuce to the cold cuts and that amount rises further.

Sources:

http://www.agroecology.org/documents/Joji/leafnitrate.pdf

J Sci Food Agric. 2014 Mar 15; 94(4):773-8.

http://ajcn.nutrition.org/content/90/1/11.full#ref-3

http://www.nlm.nih.gov/medlineplus/ency/article/000562.htm

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