| Term | Definition |
|---|
| Limnology | the study of lakes |
| glaciers | formed from gradual erosion and deposition due to advancing and retreating glaciers |
| tectonic activity | depressions formed by movements of the earth's crust |
| ecological zones | littoral zone, limnetic zone, profundal zone |
| littoral zone | extends from shore to where light no longer penetrates to support rooted plants |
| limnetic (pelagic) zone | area beyond influence of shore (photosynthesis occurs by floating microorganisms (algae)) |
| profundal zone | area of lake where not enough light penetrates for photosynthesis (lakes and deep ponds) |
| stratification due to temperature differences (summer) | warm, less dense water remains at the surface; due to density differences, stratified waters do not mix |
| stratification layers | warmwater "epilimnion", radip temperature change "thermocline", coldwater "hypolimnion" |
| epilimnion (mixed layer) | top or surface layer; warm, less dense water; dissolved oxygen is high; photosynthesis is dominant |
| metalimnion | middle layer; steep thermal gradient (thermocline) |
| hypolimnion | deeper water; cold, dense; decomposition dominates; low dissolved oxygen |
| maximum water density | about 4 degrees C |
| turnover | occurs when density at surface increases (cooling in fall, warming in spring, wind is also important); results in mixing of nutrients and dissolved oxygen |
| lake superior | largest, deepest, and coldest; retention time of 191 years |
| lake erie | smallest; exposed to most greatest amount of agriculture; most shallow; retention time of 2.6 years |
| wetlands | transitional land between terrestrial and aquatic systems; areas of land inundated by water enough to affect soils (hydric) and plants (hydophytes) |
| hydroperiod | seasonal pattern of water level in a wetland |
| definitions of what is a wetland | defined on basis of vegetation, hydrology, and/or soils |
| wetland importance | cleanse polluted waters (kidneys); prevention of floods (storage area); protection of shorelines (erosion); recharge of aquifers (water supplies); wildlife habitat; maintain plant and animal diversity |
| Central and South Florida (C&SF) Project (1948) | 1947: 108 inches of rain fell on south florida; 720 miles of levees; 1000 miles of canals; 16 pumping stations; 200 gates and other water-control structures |
| Positive impacts of C&SF | reduced flooding, increased water supply, sugar cane production, water management for south Florida |
| negative impacts of C&SF | everglades reduced by 50%; surface flows reduced by 70%; water quality, quantity, and timing modified; loss of habitat; deleterious effects on estuaries, severe winter freezes more common |
| everglades restoration project | capture most diverted water and deliver areas where needed; restore quantity, quality, and timing of water flows |
| importance of soil water | irrigation (how much water is needed), recharge zones, soil as a filter, storage of wastes, flood predictions |
| soil | is a porous medium |
| soil consists of: | solid (sand, silt, clay & organic matter), liquid (water), gas (air, water vapor, CO2) |
| porosity | amount of void space in a soil |
| volume of pores/volume of soil (solid and pores) | generally between about 0.2 to 0.45 |
| measuring porosity | volume of pores/volume of soil (solid and pores); 1. weigh saturated soil sample, 2. dry sample and weigh again, 3. obtain volume of water from mass of water lost, 4. divide volume of water by volume of soil sample |
| mass of water (g)= | volume of water (cm^3); because density of water = 1 g/cm^3 |
| volumetric moisture content | volume of water/volume of soil (cm^3/cm^3); equal to porosity when soil is fully saturated |
| measuring volumetric moisture content | moisture content=volume of water/volume of soil |
| field capacity | amount of water held against gravity |
| permanent wilting point | soil moisture content at which water is no longer available to plants |
| available water | difference between field capacity and wilting point |
| saturated | all pores are filled with water (volumetric moisture content=porosity) |
| unsaturated | pores contain air and water (volumetric moisture content < porosity) |
| soil moisture zone | region of soil water available to plants |
| intermediate zone | transition zone (water content begins to increase) |
| capillary fringe | pores are filled with water but water is held by capillary forces (moisture content equals porosity) |
| saturated zone (groundwater zone) | pores are filled with water and water moves due to gravity |
| fundamental forces driving water movement in the soil | gravity (pulls water to center of the earth); capillarity (rise of water in small tubes against the force of gravity-water cannot be drained by gravity, it can only be removed by apply suction) |
| infiltration | the movement of rain and melting snow into the soil |
| infiltration rate | rate at which water enters the soil |
| infiltration capacity | maximum infiltration rate; initially very high in dry soils, decreases as soil gets wetter, when reduced below rainfall rate water will accumulate on surface leading to runoff |
| factors affecting infiltration rates | physical factors of soils, biological, meteorological, anthropogenic (human) |
| physical factors of soils | soil permeability; macropores-channels in soil |
| biological factors of soils | organic content; presence of roots; vegetation presence/type (lessens impacts of rain drops, loosens soils, provides organic matter); animal burrows |
| meteorological factors of soils | storm intensity; antecedent moisture conditions (infiltration rates are higher in drier soils); temperature! (water viscosity increases as temperature falls) |
| anthropogenic factors of soils | urbanization; vegetation removal; agricultural methods (cultivation, grazing) |
| infiltration in ecosystems | forests (very high-organic material on forest floor and in soil, rarely does precip exceed infiltration); agricultural (variable-depends on tilling practices, crop type, grazing practices); urban (low due to impervious cover (pavement), promotes flash flooding) |
| groundwater importance | largest reservoir of unfrozen freshwater on earth (about 97%); drinking water for 53% of US (about 60% in NH); greater than 40% of streamflow in NH is from groundwater |
| groundwater | water below the water table (pores are saturated, water flows by gravity (capillary forces are unimportant)), depth of groundwater varies |
| aquifer | water bearing layer of soil that contains and transmits significant quantities of water |
| aquifer (unconsolidated) | sand and gravel |
| aquifer (consolidated) | limestone, fractured, bedrock |
| aquiclude | contains significant water but does not transmit it (low permeability media-clays, shales) |
| aquifuge | does not contain or transmit signifcant quantities of water |
| confining units | the grouping together of aquiclude and aquifuge |
| types of aquifers 1 | unconfined (water table is the upper boundry...water table=where pores are filled with water and water pressure is atmospheric) |
| types of aquifers 2 | confined (bounded on top by a confining layer; fluid is under pressure, artesian well (well in which water reaches surface without pumping)) |
| types of aquifers 3 | perched (localized zone of saturation) |
| groundwater dynamics | rate at which water moves through aquifers is a function of : the force doing the pushing (hydraulic head gradient) and the ease with which the soil will allow the water to move (hydraulic conductivity or permeability) |
| function of the porous medium | porosity, grain size, sorting, ect. |
| function of fluid properties | density and viscosity |
| increases groundwater flow rates | increase force doing the pushing (hydraulic gradient) and increase in permeability (decrease resistance to flow) |
| importance of calculating groundwater flow | to avoid over pumping (aquifer mining), assess pollution sources (Woburn, MA case study) |
| Darcy's Law | Q is proportional to area and change in h/change in I (hydraulic gradient): for a given sediment (aquifer) |
| Darcy's Law computation | Q=KA((h1-h2)/L); Q is discharge (L^3/T), K is hydraulic conductivity (L/T), change in h/change in I=hydraulic gradient (L/L), A is area (L^2) |
| groundwater velocity | v=q/n; v is velocity, n is porosity |
| how are aquifers recharged | recharge areas (downward movement of water through soil zone to saturated zone): unconfined (unsaturated zone above water table), confined (distant uplands) |
| groundwater recharge type | passive (rainfall), induced (recharge from 'losing' streams, lakes or wetlands), artificial (induced recharge by humans) |
| groundwater discharge areas | upward movement of water across water table (point where water table intersects the ground surface; 'gaining' streams, lakes, wetlands, springs) |
| unconfined aquifer yield | volume of water produced per volume of aquifer drained |
| specific yield | ranges from about 0.3 to 0.013 (typically less than porosity), water obtained by dewatering of pores |
| confined aquifer yield | storativity; ranges from about 0.005 to 0.00005, water obtained by expansion of water and compression of aquifer materials) |
| storativity | volume of water produced per volume reduction of potentiometric surface |
| affect on water table when water is pumped from aquifer | cone of depression is formed |
| cone of depression | water flows towards well to replace water that was pumped out, shape is a function of permeability and storage |
| cone of depression radius | radius is determined by how long pumping occurs; will continue to expand until recharge in creased or discharge (pumping) is decreased |
| current issues in GW management | overlapping of cones of depression (well interference), land subsidence, salt-water intrusion in coastal areas, reduced streamflow |
| aquifer mining | ogalla aquifer: area (174,000 square miles), thickness (1 to 1,300 ft), equivalent volume of water as Lake Huron, "fossil" water |
| mitigation | water conservation, improved technology (soil moisture measurements), water metering, dry-land farming, "buffalo commons" approach |
| safe yield | defined as "how much of the aquifer discharge we can capture without adversely affecting the environment; historically it has been assumed to equal recharge rates |
| change in storage | inputs - outputs; recharge - discarge; if aquifer is at equilibrium the change in storage=0, therefore recharge=discharge |
| water balance for aquifer | change in storage=recharge-discharge-pumping; if change of storage=0 and change of recharge=0, and pumping begins, then discharge must decrease |
| local issue in GW management | proposed USA Springs bottling plant in Nottingham, NH |
| dams | structures to store and redirect river water for a variety of purposes |
| types of dams | gravity concrete, gravity concrete with buttresses, concrete arch, earthen embankment |
| benefits of dams | cheap and clean electricity, flood control, recreation, drinking water, irrigation water |
| drawbacks of dams | displacement of people, silting of reservoir, failure and flooding, disruption of pulse dynamics in river, retention of important nutrients and sediments, interference with fish migration paths, temperature and DO impacts downstream |
| decommissioning | dam removal: a national movement to remove dams with few to no benefits |
| why dams cause large-scale habitat changes | riparian and upland landscape to lakes, displacement of people and towns, alteration of water flow quantity and pattern, alteration of water quality |
| Florida Everglades | 1) flood protection, water supply, irrigation (and drainage) for agriculture, 2) keep 50% natural wetlands |
| polluted water | when impurities in water are sufficient to render the water as unacceptable for its intended use |
| contaminants of polluted water | suspended and dissolved |
| suspended contaminants | undissolved solids carried by water: sediments, organic material, bacterial |
| dissolved contaminants | dissolution: solvent (water-does the dissolving), solute (substance being dissolved): salt |
| hydration | process where ions form bonds with water (polar molecule) |
| concentration | mass of substance per unit volume of solution |
| water quality | specific characteristics of water defined within the context of its intended use |
| benefits of good water quality | decreased impacts to health and property, reduced costs of water treatment, increased value of property near water, economic development, increased fisheries revenues, recreation industry, unimpaired ecosystem services |
| important water quality parameters | salinity, temperature, pH, hardness, turbidity/color, inorganic contaminants, organic contaminants, dissolved oxygen, organic matter, nutrients, bacteria and pathogens |
| major constituents of salinity | cations (sodium, magnesium, calcium, potassium) and anions (chloride, sulfate, bicarbonate) |
| temperature sources | discharge from power plants |
| temperature effects | negative impacts on stream flora and fauna, increased biological activity, increased rates of chemical reactions |
| hardness | total amount of dissolved calcium, magnesium, and iron present in water; hard: build up of scale, lack of soap lather; soft: difficulty rinsing (health concern: cardiovascular disease) |
| turbidity (suspended sediments) | consists of inorganic (silts and clays) and organic material; once the most common form of water pollution |
| sources of turbidity | natural erosional processes, poor land management practices (removal of vegetation, 90% of sediments polluting surface water from timber practices is from roads) |
| environmental concerns of sediment pollution | increased treatment costs, fish gill abrasion, smothering of benthic communities, facilitates transport of nutrients and metals, reduction in light penetration (reduces photosynthesis) |
| reduction in light penetration | light penetration diminishes exponentially with depth (reflection and absorption) and when light is absorbed it is changed to heat (light penetration will determine distribution of organisms and heat) |
| compensation point | depth where photosynthesis equals respiration (blow this depth photosynthetic organisms can't surve) |
| light penetration measured by: | photometer, secchi disk |
| inorganic compounds | carbon free, not derived from living material; easily dissolves in water; minerals; metals |
| anthropogenic sources | agricultural chemicals (used as a pesticide until development of DDT), wood preservations; natural sources (found in primary sulfide minerals, granite bedrock) |
| organic compounds | contains carbon, derived from living organisms (tend not to disolve well); natural (oil, decomposing organic material)(synthetic: pesticides) |
| biodegradable | can be broken down easily biologically |
| non-biodegradable | resistant to biological breakdown, natural (tannins and lignins), anthropogenic (pesticides) |
| benefits of pesticides | reduction in pests (greater food yields, decreases in disease) |
| drawbacks of pesticides | not easily decomposed, detrimental health effects to humans and wildlife (endocrine disruptor) |
| DDT | used to kill mosquitoes (control malaria), 25 million lives saved, banned in 1972 |
| integrated pest management | focus away from chemical-only solutions |
| integrated pest management process | determine need; natural predators/parasites (native, non-native or introduced); mechanical removal; pesticides: natural, synthetic; determine outcome and further |
| benthic macroinvertebrates | used widely to assess health, integrate environmental conditions over time, not very mobile, relatively easy to identify, easy to sample |
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