Sprinkler irrigation coverage is illustrated in the image here that comes from Lecture 3 in a course in the Biological and Irrigation Engineering department at Utah State University. Agricultural students anywhere across the world can learn water handling and conservation from the Utah State lectures. IrrigationTutorials.com is a website with a broad range of tutorials on the practicalities of selecting and installing irrigation systems. Extensive details of sprinkler irrigation are provided by the University of Georgia College of Agricultural and Environmental Sciences in a website section on factors to consider in selecting a farm Irrigation system. Websites about irrigation are interconnected richly, making one of humankind’s most ancient technologies a click or two away from anyone with Net access who wants to understand and implement irrigation.
To explore a learn node to study and report on something for biology, why not the common nematode. The “What are Nematodes?” webpage at the University of Nebraska-Lincoln begins:
Nematodes are the most numerous multicellular animals on earth. A handful of soil will contain thousands of the microscopic worms, many of them parasites of insects, plants or animals. Free-living species are abundant, including nematodes that feed on bacteria, fungi, and other nematodes, yet the vast majority of species encountered are poorly understood biologically.
You can click from this explanatory page to something of an illustrated parts list for nematodes called: Interactive Diagnostic Key to Plant Parasitic, Freeliving and Predaceous Nematodes. Shown here is one of the head appendages. Bananas are a fruitful place to observe nematodes in action; excellent materials for that topic can be found on IITA Research to Nourish Africa’s Banana Nematology pages. Described there is nematode damage and symptoms caused not by “a single nematode species attacking bananas, but a complex of several species.” Nematodes can also play role in insect control. A University of Florida article explains how biological control nematodes work. The Nematode.net Genome Sequencing Center at Washington University in St. Louis is an detailed repository of nematode facts and images, the picture of the Meloidogyne hapla at the top of this post.
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This learn node clusters material about the dangerous presence of arsenic in ground water of the United States as illustrated the map here from the U.S. Geological Survey’s Water Quality Assessment Analysis of Trace Elements webpage. Information on the world wide arsenic in drinking water problem is abundant on the World Health Organization Arsenic in drinking water Fact Sheet.
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A look at an example of the arsenic problem in drinking water is provided by the American Museum of Natural History’s 2007-08 special exhibit on Water, which describes a situation where arsenic foiled attempts to get good water by drilling below bacterial contamination:
In Bangladesh, millions of deep wells were drilled to end use of bacteria-laced surface water. It worked: for instance, infant mortality dropped sharply. But many of the wells turned out to contain high levels of naturally occurring arsenic—an extremely toxic chemical element with serious health effects. Today, experts are working to develop inexpensive methods of removing arsenic from the water.
So how would you get arsenic out of water? Three pages from a Stiochiometry tutorial at Carnegie Mellon University’s openlearning initiative describes a method developed by Prof. Fakhrul Islam, a chemist at Bangladesh’s Rajshahi University. The tutorial is Arsenic remediation: Using powder to absorb arsenic from water.