Contaminants

Contaminants may include organic and inorganic substances.

Some organic water pollutants are:

• Insecticides and herbicides, a huge range of organohalide and other chemicals
• Bacteria, often is from sewage or livestock operations
• Food processing waste, including pathogens
• Tree and brush debris from logging operations
• VOCs (Volatile organic compounds), such as industrial solvents, from improper storage
• Petroleum Hydrocarbons including fuels (gasoline, diesel, jet fuels, and fuel oils) and lubricants (motor oil) from oil field operations, refineries, pipelines, retail service station's underground storage tanks, and transfer operations. Note: VOCs include gasoline-range hydrocarbons.

Some inorganic water pollutants include:

• Heavy metals including acid mine drainage
• Acidity caused by industrial discharges (especially sulfur dioxide from power plants)
• Pre-production industrial raw resin pellets, an industrial pollutant
• Chemical waste as industrial by products
• Fertilizers, in runoff from agriculture including nitrates and phosphates
• Silt in surface runoff from construction sites, logging, slash and burn practices or land clearing sites

Sources of water pollution

Some of the principal sources of water pollution are:

• Geology of aquifers from which groundwater is abstracted
• Industrial discharge of chemical wastes and byproducts
• Discharge of poorly-treated or untreated sewage
• Surface runoff containing pesticides or fertilizers
• Slash and burn farming practice, which is often an element within shifting cultivation agricultural systems
• Surface runoff containing spilled petroleum products
• Surface runoff from construction sites, farms, or paved and other impervious surfaces e.g. silt
• Discharge of contaminated and/or heated water used for industrial processes
• Acid rain caused by industrial discharge of sulphur dioxide (by burning high-sulphur fossil fuels)
• Excess nutrients are added (eutrophication) by runoff containing detergents or fertilizers
• Underground storage tank leakage, leading to soil contamination, and hence aquifer contamination
• Inappropriate disposal of various solid wastes and, on a localized scale, littering
• Oil spills

Water pollution

From Wikipedia, the free encyclopedia

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Raw sewage and industrial waste flows into the U.S. from Mexico as the New River passes from Mexicali, Baja California to Calexico, California

Water pollution is a large set of adverse effects upon water bodies such as lakes, rivers, oceans, and groundwater caused by human activities.

Although natural phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause major changes in water quality and the ecological status of water, these are not deemed to be pollution. Water is only called polluted when it is not able to be used for what one wants it to be used for. Water pollution has many causes and characteristics. Increases in nutrient loading may lead to eutrophication. Organic wastes such as sewage impose high oxygen demands on the receiving water leading to oxygen depletion with potentially severe impacts on the whole eco-system. Industries discharge a variety of pollutants in their wastewater including heavy metals, resin pellets, organic toxins, oils, nutrients, and solids. Discharges can also have thermal effects, especially those from power stations, and these too reduce the available oxygen. Silt-bearing runoff from many activities including construction sites, deforestation and agriculture can inhibit the penetration of sunlight through the water column, restricting photosynthesis and causing blanketing of the lake or river bed, in turn damaging ecological systems.

Pollutants in water include a wide spectrum of chemicals, pathogens, and physical chemistry or sensory changes. Many of the chemical substances are toxic. Pathogens can produce waterborne diseases in either human or animal hosts. Alteration of water's physical chemistry include acidity, conductivity, temperature, and eutrophication. Eutrophication is the fertilisation of surface water by nutrients that were previously scarce. Even many of the municipal water supplies in developed countries can present health risks. Water pollution is a major problem in the global context. It has been suggested that it is the leading worldwide cause of deaths and diseases,^[1][2] and that it accounts for the deaths of more than 14,000 people daily.^[2]

Hydrometry

From Wikipedia, the free encyclopedia

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Hydrometry is the monitoring of the components of the hydrological cycle including rainfall, groundwater characteristics, as well as water quality and flow characteristics of surface waters.^[1] The etymology of the term hydrometry derives from the Greek: Hydro = water; metros = measuring.

Branches of hydrology

Chemical hydrology is the study of the chemical characteristics of water.

Ecohydrology is the study of interactions between organisms and the hydrologic cycle.

Hydrogeology is the study of the presence and movement of water in aquifers.

Hydroinformatics is the adaptation of information technology to hydrology and water resources applications.

Hydrometeorology is the study of the transfer of water and energy between land and water body surfaces and the lower atmosphere.

Isotope hydrology is the study of the isotopic signatures of water.

Surface hydrology is the study of hydrologic processes that operate at or near the Earth's surface.

Hydrologic cycle

The central theme of hydrology is that water moves throughout the Earth through different pathways and at different rates. The most vivid image of this is in the evaporation of water from the ocean, which forms clouds. These clouds drift over the land and produce rain. The rainwater flows into lakes, rivers, or aquifers. The water in lakes, rivers, and aquifers then either evaporates back to the atmosphere or eventually flows back to the ocean, completing a cycle.

History of hydrology

Hydrology has been a subject of investigation and engineering for millennia. For example, in about 4000 B.C. the Nile was dammed to improve agricultural productivity of previously barren lands. Mesopotamia/Mesopotamian towns were protected from flooding with high earthen walls. Aqueducts were built by the Ancient Greece/Greeks and Ancient Romans, while the History of China built irrigation and flood control works. The ancient Sinhalese used hydrology to build complex Irrigation Works of Ancient Sri Lanka, known for invention of the Valve Pit which allowed construction of large reservoirs, anicuts and canals which still function.

Vitruvius/Marcus Vitruvius, in the first century B.C., described a philosophical theory of the hydrologic cycle, in which precipitation falling in the mountains infiltrated the earth's surface and led to streams and springs in the lowlands. With adoption of a more scientific approach, Leonardo da Vinci and Bernard Palissy independently reached an accurate representation of the hydrologic cycle. It was not until the 17th century that hydrologic variables began to be quantified.

Pioneers of the modern science of hydrology include Pierre Perrault, Edme Mariotte and Edmund Halley. By measuring rainfall, runoff, and drainage area, Perrault showed that rainfall was sufficient to account for flow of the Seine. Marriotte combined velocity and river cross-section measurements to obtain discharge, again in the Seine. Halley showed that the evaporation from the Mediterranean Sea was sufficient to account for the outflow of rivers flowing into the sea.

Advances in the 18th century included the Bernoulli piezometer and Bernoulli's equation, by Daniel Bernoulli, the Pitot tube. The 19th century saw development in groundwater hydrology, including Darcy's law, the Dupuit-Thiem well formula, and Hagen-Poiseuille's capillary flow equation.

Rational analyses began to replace empiricism in the 20th century, while governmental agencies began their own hydrological research programs. Of particular importance were Leroy Sherman's unit hydrograph, the infiltration theory of Robert E. Horton, and C.V. Theis's Aquifer test/equation describing well hydraulics.

Since the 1950's, hydrology has been approached with a more theoretical basis than in the past, facilitated by advances in the physical understanding of hydrological processes and by the advent of computers and especially Geographic Information Systems (GIS).