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9. Living Systems

How Does Energy Flow in Living Systems?

2016-07-28. How Irrigation in Asia Affects Rainfall in Africa. By Sarah Stanley, EoS Earth and Space News, AGU.

2015-06-22. Amazon Rain Forest Nourished by African Dust. By Terri Cook, EOS publication of AGU.

2009 October 15. Deep-Sea Microbes May Answer Long-Standing Question About Earth's Nitrogen Cycle. NSF Release 09-201.Excerpt: ...Although lightning, combustion, and other non-biological processes can create reduced nitrogen, far more is generated by nitrogen-fixing microorganisms such as bacteria, in particular, photosynthetic aquatic cyanobacteria. These organisms produce the bulk of the nitrogen available to living things in the ocean.
When researchers add up all known sources of fixed nitrogen--biological and otherwise--in the global nitrogen cycle, and compare it to the sinks (biological uptake for growth and energy), they come up short. More nitrogen appears to be used than is being made. The "nitrogen budget," in effect, does not balance.
The question has been whether the nitrogen cycle is out of balance, or whether the known inventories of sources and sinks are incomplete, says Victoria Orphan, a geobiologist at Caltech.
Orphan, along with Caltech graduate student Anne Dekas and Caltech postdoctoral researcher Rachel Poretsky, suggest the answer is, at least in part, an incomplete catalogue of the sources of fixed nitrogen.
...The team studied ocean sediment samples in methane cold seeps 20 miles off northern California at a depth of 1,800 feet. The area, known as the Eel River Basin, is in a region that supports high levels of natural methane seepage at the sea-floor.
... tiny microbial conglomerations ... averaging 500 cells each, consist of two types of anaerobic microorganisms living in a unique symbiotic relationship fueled by methane. ... a bacterium ... reduces the chemical sulfate into sulfide generate energy. The second is a methane-oxidizing archaeon ...Working together, these two symbionts are responsible for consuming the majority of the naturally-released methane in the deep sea.
Although these symbiotic associations themselves are not new--the conglomerations were found about a decade ago--the scientists discovered something unexpected: the methane-consuming archaea were actively fixing nitrogen, and sharing it with their bacterial neighbors.
This is the first time nitrogen fixation has been documented in methane-oxidizing archaea, say the scientists....

2009 May 28. Serving Suggestion. By Karen Solomon, OnEarth (NRDC ISSUE: Summer 2009) Excerpt: With Sasha and Malia growing arugula in the White House garden, and with more and more farmers' markets on our streets, it seems shocking that prefab Tater Tots and canned fruit cocktail should continue to rule the lunchrooms of our public schools.
Until October 2005, the Berkeley Unified School District in California was no exception. Its 9,000 students were served the usual highly processed, highly subsidized heat-and-serve dreck that passed for the noontime meal. That is, until Ann Cooper became director of nutrition services, making a radical shift from chicken nuggets to real chicken, fresh produce instead of ketchup packets, and whole-grain, real bean and cheese nachos with not a can of cheese sauce in sight. Now Cooper, who first made a name for herself on the celebrity-chef circuit, is taking her mission and her menu to school cafeterias nationwide.
"High-fat, high-sugar, high-salt diets with very few fruits and vegetables and no whole grains will lead to a generation of kids who, for the first time, will die at a younger age than their parents," says Cooper, citing Centers for Disease Control statistics that a third of our nation's children are overweight or obese. Because minority students are most affected by what's on the daily cafeteria tray, real lunch reform is "the social justice issue of our time," Cooper says. "We can't spend another dollar per day per child to feed them healthy food?" she yells in exasperation. "We can either pay for lifelong wellness now, or pay later for a tsunami of diabetes. And these kids can't learn if they're not well nourished."...

2008 July 18. Saharan dust storms sustain life in Atlantic Ocean. Eureka Alert. Excerpt: Research at the University of Liverpool has found how Saharan dust storms help sustain life over extensive regions of the North Atlantic Ocean.
Working aboard research vessels in the Atlantic, scientists mapped the distribution of nutrients including phosphorous and nitrogen and investigated how organisms such as phytoplankton are sustained in areas with low nutrient levels.
They found that plants are able to grow in these regions because they are able to take advantage of iron minerals in Saharan dust storms. This allows them to use organic or 'recycled' material from dead or decaying plants when nutrients such as phosphorous – an essential component of DNA – in the ocean are low...
"These findings are important because plant life cycles are essential in maintaining the balance of gases in our atmosphere. In looking at how plants survive in this area, we have shown how the Atlantic is able to draw down carbon dioxide from the atmosphere through the growth of photosynthesising plants."

2005 April 21. NASA RELEASE: 05-100. NASA Study Finds Snow Melt Causes Large Ocean Plant Blooms. A NASA funded study has found a decline in winter and spring snow cover over Southwest Asia and the Himalayan mountain range is creating conditions for more widespread blooms of ocean plants in the Arabian Sea. The decrease in snow cover has led to greater differences in both temperature and pressure systems between the Indian subcontinent and the Arabian Sea. The pressure differences generate monsoon winds that mix the ocean water in the Western Arabian Sea. This mixing leads to better growing conditions for tiny, free-floating ocean plants called phytoplankton. ...When winter and spring snow cover is low over Eurasia, the amount of solar energy reflected back into the atmosphere is less. A decline in the amount of snow cover means less of the sun's energy goes towards melting of snow and evaporation of wet soil. As a result the land mass heats up more in summer creating a larger temperature difference between the water of the Arabian Sea and the Indian subcontinent landmass. The temperature difference is responsible for a disparity in pressure over land and sea, creating a low pressure system over the Indian subcontinent and a high pressure system over the Arabian Sea. This difference in pressure causes winds to blow from the Southwest Arabian Sea bringing annual rainfall to the subcontinent from June to September. In the Western Arabian Sea, these winds also cause upwelling of cooler nutrient-rich water, creating ideal conditions for phytoplankton to bloom every year during summer. ... while large blooms of phytoplankton can enhance fisheries, exceptionally large blooms could be detrimental to the ecosystem. Increases in phytoplankton amounts can lead to oxygen depletion in the water column and eventually to a decline in fish populations. More info


Articles from 2005–present


Ecosystem Change-
Chapter 2
: Energy Through a System
Chapter 5: Carbon in the Biosphere

Losing Biodiversity
Chapter 5: Soil, the Living Skin of the Earth
Chapter 7: One Global Ocean