October 1, 2022
This one is not for all of the readers since it is a bit technical.
Water is one of the lightest of those molecules that are most abundant on Earth. In addition, being made of only three atoms, H-O-H or H2O, it has a simple configuration, one oxygen atom and two hydrogen atoms (at an angle of 104.5° to each other). This simple molecule has several exceptional properties that are all the result of the fact that one large oxygen atom forms a bond with two very small hydrogen atoms, the smallest atom that exists. Oxygen is the dominant partner and attracts the hydrogen electrons, which leads to the unusually strong polarity of the water molecule, which has definite positive and negative poles. The strength of the polarity of a molecule is expressed in the relative dielectric constant. Of all the natural substances, water has the largest dielectric constant. This, together with the small size of the water molecule, is the reason why water is the best known so-called “natural” solvent. It has also been referred to as the “universal” solvent because it is capable of dissolving many substances. This property of water arises from the aforementioned dipolar nature of water molecules. Water molecules effectively surround positively charged ions (cations) and negatively charged ions (anions), which serve to prevent them from precipitating as a solid. This means that wherever water goes, either through the ground or through one’s body, it carries with it various solutes such as dissolved minerals, nutrients, organics, and heavy metals.
Interestingly, the aforementioned hydrogen bonds are responsible for an additional physical property of water that is important for the Earth system: water’s extremely high heat capacity and high vaporization and fusion temperatures. Large amounts of heat are needed to melt or vaporize water and are stored in the water molecule. This high capacity for heat storage is important, not just in nature, but it is also used by humans, e.g., to cool machinery. To melt ice, 146 BTU/lb. (340 J/g) are needed and released by condensation or freezing, respectively. (It is this significant difference in energy level during a phase change that provides crystallization with an advantage over evaporation for desalination processes, a topic to be discussed in a later article.)
The story is a little different here at home in the USA. The USEPA (EPA), in partnership with state and local governments, is responsible for improving and maintaining water quality. These efforts are centered around one theme: maintaining the quality of drinking water. This is addressed by monitoring and treating drinking water prior to consumption and by minimizing the contamination of surface waters and protecting against contamination of ground water needed for human consumption.
The most severe and acute public health effects from contaminated drinking water, such as cholera and typhoid, have been eliminated in America. However, some less acute and immediate hazards remain in the nation’s tap water. These hazards are associated with a number of specific contaminants in drinking water. Contaminants of special concern to the EPA are lead, radionuclides, microbiological contaminants, and disinfection byproducts. These are detailed below.
The primary source of lead in drinking water is corrosion of plumbing materials, such as lead service lines and lead solders, in water distribution systems, and in houses and larger buildings. Virtually all public water systems serve households with lead solders of varying ages; and most faucets are made of materials that can contribute some lead to drinking water.
Radionuclides are radioactive isotopes that emit radiation as they decay. The most significant radionuclides in drinking water are radium, uranium, and radon, all of which occur naturally in nature. While radium and uranium enter the body by ingestion, radon is usually inhaled after being released into the air during showers, baths, and other activities such as washing clothes or dishes. Radionuclides in drinking water occur primarily in those systems that use ground water. Naturally occurring radionuclides seldom are found in surface waters (such as rivers, lakes, and streams). Water contains also many microbes – bacteria, viruses, and protozoa. Although some organisms are harmless, others can cause disease. Contamination continues to be a national concern because contaminated drinking water systems can rapidly spread disease.
Half of all Americans and 95 percent of rural Americans use ground water for drinking water This includes residents of Long Island; in effect, this includes the boroughs of Queens and Brooklyn plus the counties of Nassau and Suffolk. Pollutants were found in drinking water through testing water in different locations at different times. Several public water supplies using ground water exceeded EPA’s drinking water standards for inorganic substances (fluorides and nitrates). Major problems were reported from toxic organics in some wells in almost all states east of the Mississippi River. Trichloroethylene, a suspected carcinogen, was the most frequent contaminant found. The .EPA’s Ground Water .Supply Survey showed that 20 percent of all public water supply wells (29 percent in urban areas) had detectable levels of at least one volatile organic. Furthermore, at least thirteen organic chemicals that are confirmed animal or human carcinogens have been detected in drinking water wells.
The reader should also note that water is the original renewable resource. Although the total amount of water on the surface of the Earth remains fairly constant over time, individual water molecules carry with them a rich history. The water molecules contained in the fruit one ate yesterday may have fallen as rain last year in a distant place or could have been used decades, centuries, or even millennia ago by one’s ancestors.
Water is always in motion, and the hydrologic cycle describes this movement from place to place. The vast majority of solar energy heats water at the surface of the ocean, and some of it evaporates to form water vapor. Air currents take the vapor up into the atmosphere along with water transpired from plants and evaporated from the soil. The cooler temperatures in the atmosphere cause the vapor to condense into clouds. Clouds move around the world until the moisture capacity of the cloud is exceeded, and the water falls as precipitation. Most precipitation in warm climates falls back into the oceans or onto land where the water flows over the ground as surface runoff. Runoff can enter rivers and streams, which transport the water to the oceans, accumulate and be stored as freshwater in lakes, or soak into the ground as infiltration. Some of this water may infiltrate deep into the ground and replenish aquifers which store huge amounts of freshwater for long periods of time. In cold climates, precipitation falls as snow and can accumulate as ice caps and glaciers which can store water for thousands of years. Throughout this cycle, water picks up contaminants originating from both naturally occurring and anthropogenic sources. Depending upon the type and amount of contaminant present, water present in rivers, lakes, and streams or beneath the ground may become unsafe for use.
The reality is that our nation really does not have a water problem at this time. However, the world needs to prepare for an insufficient and potentially depleted water supply. In terms of conservation, one method of reducing a building’s water consumption is through the use of low volume toilets. The standard toilet uses as much as 5 gallons of water per flush, whereas some water-saving models use as little as 2 quarts. This can lead to substantial water savings, especially in public and commercial buildings. Another major source of water consumption is the irrigation of landscaped areas. This consumption may be reduced through the careful selection of landscape materials. Although conservation is here for the present, desalination (a topic to be addressed two months from now), disinfection, and nanoparticle-related treatment appear to be the major growth areas for the future. In any event, water will achieve a greater significance in the coming years and probably impact society in ways not presently imagined.
I close with a quote from my memoirs. “Water has always fascinated me; where it comes from, how we use it, … etc. I recently convinced myself that there is a viscous water cycle on planet Earth. What an unbelievable resource that – get this – is automatically recycled. It’s a shame nature didn’t bother to do the same with our other resources.”
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NOVEMBER 1: On the OHI Day V
DECEMBER 1: On My Two Patents
JANUARY 1: On the Ultimate Quiz V