Water Pollution Flashcards
Any physical, biological, or chemical change in water quality that adverselyaffects living organisms or makes water unsuitable for desired uses.
water pollution
The most serious water pollutants in terms of human health worldwide
pathogenic organisms
The main source of these pathogens is
untreated or improperly treated human wastes
The WHO estimates that ______________ of all
sickness and disease in less-developed countries can be attributed to waterborne infectious agents and inadequate sanitation
80%
The amount of oxygen dissolved in water is a good indicator of water quality and of the kinds of life it will support.
oxygen level
Water with an oxygen content of ________ will support game and other desirable forms of aquatic life.
6 ppm
Water with less than _____ oxygen will support mainly worms, bacteria, fungi, and other detritus feeders and decomposers.
2 ppm
Oxygen is removed from water by ____________ and chemical processes that consume oxygen
respiration
is the amount of dissolved oxygen that must be present in water in order for microorganisms to decompose the organic matter in the water, thus a useful test for the presence of organic waste in water
biochemical oxygen demand (bod)
uses a strong oxidizing agent (dichromate ion in 50% sulfuric acid) to completely breakdown all organic matter in a water sample.
chemical oxygen demand (cod)
the oxygen decline downstream.
oxygen sag
- Further downstream, the water may become so oxygen-depleted that only the most resistant microorganisms and invertebrates can survive.
dead zone
rivers and lakes that have clear water and low biological productivity.
oligotrophic
waters that are rich in organisms and organic materials. Eutrophication is an increase in nutrient levels and biological productivity.
eutrophic
Some toxic inorganic chemicals are released from rocks by ____________, are carried by runoff into lakes or rivers, or percolate into groundwater aquifers.
weathering
Some soils contain naturally high concentrations of soluble salts, including toxic selenium and arsenic.
nonmetallic salts
Salts, such as _________-, that are non-toxic at low concentrations also can be mobilized by irrigation and concentrated by evaporation, reaching levels that are toxic for many plants and animals.
sodium chloride
Globally, 20% of the world’s irrigated farmland is estimated to be affected by __________
salinization
Acids are released as by-products of industrial processes, such as leather tanning, metal smelting and plating, petroleum distillation ,and organic chemical synthesis
acids and bases
is an especially important source of acid water pollution.
coal mining
due to acid precipitation has been reported in about 200lakes in the Adirondack Mountains of New York State and in several
thousand lakes in eastern Quebec, Canada.
aquatic damage
Include drugs, pesticides, and other industrial substances
organic pollutants
from shipwrecks and well blowouts, such as the 2010explosionofthe Deepwater Horizon in the Gulf of Mexico, can be disastrous for ecosystems and local economies.
oil spills
Erosion and runoff from croplands contribute about 25 billion metric tons of soil, sediment, and suspended solids to world surface waters each year
sediments
Raising or lowering water temperatures from normal levels can adversely affect water quality and aquatic life
thermal pollution
The cheapest and most effective way to reduce pollution is usually to avoid producing it or releasing it to the environment in the first place.
source reduction
The first step in municipal waste treatment. It physically separates large solids from the waste stream
primary treatment
Consists of biological degradation of dissolved organic compounds. The effluent from primary treatment flows into a trickling filter bed, an aeration tank, or a sewage lagoon
secondary treatment
a hybrid between a traditional septic tank andafull
sewer system. A tank near each dwelling collects and digests solid waste just like a septic system. Rather that using a drain field, however, dispose of liquids effluents are pumped to a central treatment plant.
effluent sewerage
can cut secondary treatment cost to one-third of mechanical treatment costs, or less. Effluent from these operations can be used to irrigate crops or even raise fish for human consumption if care is taken to first destroy pathogens
constructed wetlands
There are two basic methods used to purify water of dissolved minerals:
filtration and distillation
means finding remedies for problems. New developments in environmental engineering are providing promising solutions to many water pollution problems
remediation
confine or restrain dirty water or liquid in situ or cap the surface with an impermeable layer to divert surface water or groundwater away from the site and to prevent further pollution.
containment methods
pump out polluted water so it can be treated. Manypollutants can be destroyed or detoxified by chemical reactions that oxidize,reduce, neutralize, hydrolyze, precipitate, or otherwise change their chemical
composition.
extraction techniques
living organisms used effectively and inexpensively to clean contaminated water. This can be carried out in tanks or troughs
bioremediation
