Lectures 19-21 + TBL 6 Flashcards
Reactions in which elements may be converted from one into another, involving particles within the nucleus, and a release or absorption of large amounts of energy. The rate of the reaction is not influenced by external factors
Nuclear reactions
nuclear particles (protons and neutrons)
Nucleons
Different forms of the same element
isotopes
When unstable nuclei emit one or more particles and / or electromagnetic radiation
radioactive decay
High energy particles and ____ size particles can penetrate _____
smaller, more
When high energy photons with very short wavelength are emitted, which changes neither the atomic mass or mass number. Accompany most nuclear reactions and convertes something from an excited to a relaxed state
gamma radiation
Emission of a particle equivalent to a He nucleus (mass # = 4, atomic mass = 2)
alpha radiation
Emission of either an electron or a positron from the nucleus
beta radiation
When an electron is emitted in beta radiation, the atomic number ____ by 1. When a positron is emitted in beta radiation, the atomic number ____ by 1
increases, decreases
Radionuclides have different rates of decay/ Each nuclide has a characteristic ____ ____ and _____ ____. Rates of decay are independent of ___, ____, _____, etc., and obey first order _______
decay constant, half life, T, P, S, kinetics
The time interval over which the initial number of atoms is exactly halved
half life
As t–> inifinity, the number of parent atoms approaches ______, and the number of daughter atoms approaches ______. The range of the decay constant can be from ______ (fast), to _____ (slow)
0, N0, 3x10^6s, 2x10^-18s
From the earth or cosmic sources
natural environmental radioactivity
Radioactivity from the time earth was formed (~4.6x10^9 years)
primary / primordial radioactivity
The primary radioactive elements
40K, 232Th, 235U, 238U
_____ is naturally abundant, and primordial, meaning it has a long ______. About _____ the 238U originally present on earth has decayed.
238U, half life, half
As U decays, the daughters formed are:
Th, Pa, Ra, Rn, Po, Pb, Bi
The daughters formed from U decay are also ________ and decay by either ____ or ____ decay with varying ______ until the final stable ____ is formed. With each decay, there is a change in _______. ___ and ____ are very soluble while ___ ______ _____ ____ and ____ are not. ____ is a gas
radioactive, alpha, beta, decay constants, Pb, chemistry, U, Ra, Pa, Th, Po, Bi, Pb, Rn
The soluble U species in aqueous solution are
(UO2)(OH)5+, (UO2)(CO3)34-
radiation from outside earth, mainly a stream of nuclei and protons. React with the atmosphere to produce secondary particles
secondary / cosmogenic
Examples of secondary radiation
3H, 14C, 7Be, 26Al, 32Si, 39Ar
examples of man-made / anthropogenic environmental radioactivity
- nuclear weapons, 2. nuclear fuel cycle (reactors, reprocessing plants), 3. others (low level waste, naval reactors, accidents)
All radioactive species can end up in
soils and surface waters
In general, exposure from radiation from _____ ____ is greater than from _____ ____
natural sources, artificial sources
Most exposure to radiation is from ____ sources (76.1%), the next is ____ (22.9%) Typically the greatest exposure is from _____ because it is a gas. In water, the greatest concern is______. Natural exposure is greater at higher ______ from cosmic rays, thus pilots, flight attendants and people who live in mountains have higher exposure
natural, medical (x-rays), Rn, Ra2+, elevation
Radon is naturally produced in the environment, from decay of U in ____, ____ or _____. It is ____, ______, tasteless, and emits ______ radiation. It is a gas, moves through soil, and escapes to the ______ or seeps into buildings. When radon is confined to enclosed or poorly -______ spaces, it _______ to high levels. Radon levels are generally highest in ______ and crawl spaces, because these areas are nearest to the source and poorly ventilated. In ____ ____ radon gas is very low level and does not pose a health risk
rock, soil, water, colourless, odorless, ionizing, atmosphere, ventilated, accumulates, basements, open air
the production of ions which is the primary effect of alpha and beta particles and gamma rays on materials.
ionizing radiation
alpha particles are ____ do not ____ deeply, but are very harmful if _____ because they produce a lot of ______. Beta particles are _____ penetrating than alpha, but less ______ per unit (less ionization), ______ penetrate the most.
large, penetrate, swallowed, ions, more, energy, gamma rays
Radiation initiates harmful reactions in _____, resulting in acute radiation poisoning. _____ ____ is destroyed, there is _____ damage, and _____
tissue, bone marrow, genetic, cancer
The factors in ranking danger of radiation
- type of radiation, 2. energy of radiation, 3. half-life of source
_____ life times are not very harmful in the environment because they ____ quickly. Long life times are _____ harmful because they are _____ _____. ____ _____ are the most hazardous
short, decay, not, low activity, intermediate life-times
In drinking water, the common radionuclides are _____, ____, and ____, which are leached from _____. _____ is of the most concern, as it often occurs beyond the _____ _____ _____. However, is is well removed by ________ processes (like Ca). Nuclear ____, _____ and _____ have increased concern about contamination of water by other sources.
U, Ra, K, minerals, Ra, maximum contaminant level, softening, weapons, power, accidents
Human sources of ______ to the atmosphere over the last 60 years was much _____ than the natural levels in the ______. _____ released more than ______, but less than ______
Cesium-137. less. ocean. Fukushima, three-mile island, chernobyl
____ ___ _____ _____ released much more radioactivity in the ocean than _____ ______. However, there is still much more _____ _____ radiation
global nuclear weapons testing, reactor accidents, natural occurring
The main sources of pollutant acidity are (3)
- acid rock drainage, 2. industrial wastes, 3. acid rain
The problem with pollutant acidity is that ___ ___ are sensitive to ____ extremes, and have a maximal __ ___
aquatic biota, pH, growth rate
Acid rain is a ______ problem and a danger to ____, ____, _____, _____, etc. It is associated with heavy _______. Normal pH of rain is ______ due to CO2. Acidic rain has a pH of ______, but can be as low as ______. Areas are least sensitive to the effects of acid rain if they are primarily comprised of _______ ____ (CaCO3) The ____ ion can offset the added _____ from the acid rain
regional, crops, lakes, buildings, forests, industry, 5.6, 4-5, 2, carbonate bedrock, carbonate, H+
The main sources of acid rain are from ______ and _____ in the atmosphere. ____ of these oxides produces ___, _____, and ______. It can also be from ______.
sulphur oxides, nitrogen oxides, oxidation, HSO4, HNO4, H2SO3,CO2
The sources of sulphur oxides include _____ burning, roasting of ___ ____ _____. The _____ _____ in Sudbury Ontario is the world’s largest single point emission source of _____.
coal, metal sulphide ores, Ni smelter, SO4
Sources of nitrogen oxides include ______ sources, and oxidizing agents in the atmosphere are ______, _______, and _______
combustion, ozone, hydrogen peroxide, peroxides (CH3O2)
Even in highly polluted atmospheres, NO2 and SO2 are _______. But even at low concentrations, SO2, ______, and ______ have a bigger effect on ___ in fresh waters that are _____ ____, than CO2, as they are more ____ in water (bigger _____) and they are stronger _____ (bigger ____)
<1ppm, SO3, HNO3, pH, poorly buffered, soluble, Kh, acids, ka
Acid rain can impact plants in that pH < _____ damages leaves and alters ____ ____. In water, it is a problem where underlying rocks provide poor ____ ____ (ie. limestone vs granite (no carbonates)). Some of the worst hit areas are ______, ______, Scandinavia, and Germany. Lowering pH increases the _______ of many metals (ex. Al)
3.5, soil chemistry, buffering capacity, E. Canada, N.E. USA, solubility
Some natural sources of salts include ______ _____ and ____ ______ Anthropogenic sources include _____ ____, road ______, dissolution from ______ ____, ground water ________, and ______
sea spray, evaporative basins, water softening, de-icing, ore piles, intrusions, irrigation
While light rainfall is taken up by ____ ___ and evaporates back to the air fairly quickly, heavier rain and ______ can cause water to penetrate deeper into the soil before _______. Heavy ____ for crops and landscaping can penetrate to layers of the soil that contain higher levels of ______ ____, _____ and _____ them and bring them back to the surface as the water evaporates.
plant roots, irrigation, evaporation, irrigation, mineral salts, dissolve, mobilize
