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pH
number of H+ ions in a solution
formula for pH
pH=-log[H+]
what is neutral pH
7
what is low pH
acidic
what is high pH
basic
acid
a substance that produced H+ ions in water
base
a substance that produces OH- in water
why is pH is a master variable in nature?
it affects chemical, physical, and biological properties and reactions
what are some of the properties that pH affects
nutrient availability, metal toxicity/solubility, microbial activity
water pH importance
problematic for biology and element cycling, controlled by interactions in environment, systems can be sensitive/insensitive
pH ranges
volcano lake: 0-1, bogs: 2-6, most temperate and tropical lakes: 7-9, desert lakes: 10+
pH of unpolluted rain
5.3
acids come from
acid sulfate rocks, volcanoes, organic matter, and biology
buffering capacity
ability to absorb H+ ions when acid is added to water without a change in pH
where does buffering capacity come from
carbonates (limestones, dolostones, etc)
redox reactions
a chemical reaction in which the oxidation states of atoms are changed
oxidation
loss of electrons
reduction
gain of electrons
decreasing energy yield
O2 → NO3- → Fe2+ → SO4- → CO2
hot spots/hot moments
locations or times of intense geochemical processing due to electron acceptors and electron donors coming together under just the right conditions
riparian wetlands
seasonally flooded periods
why is running water important
it transports 15-20 tonnes annually to the ocean
load
the amount of material in transport
bed load
particles moving along the stream bottom
suspended load
particles moving while suspended in the water column
dissolved load
dissolved materials in transport
longitudinal profiles
zone 1: headwaters, zone 2: transfer zone, zone 3: depositional zone
river continuum concept
headwater → mouth, gradient of physical, chemical, and biological features
biodiversity
variety and variability of life on Earth. Is a measure of variation at the genetic, species, and ecosystem level
hotspot (biodiversity)
a geographic area that harbors a disproportionate number of species, usually endemic; 25 hotspots on Earth and 1.4% of land
species diversity
measure of biodiversity using species richness and species evenness
species richness
the number of different species represented in an ecological community, landscape, or region
species evenness
the proportions of each species
food chain
linked feeding series
trophic levels
feeding status
food web
map of feeding interactions in a community
functional feeding groups
shredders, grazers, collectors, carnivores
ecological integrity
the capacity of supporting and maintaining a balanced, integrated, adapted community of organisms having a species composition, diversity, and functional organization
biocriteria
a qualitative index on each species
biodiversity crisis
land use change, invasive species, over exploitation, pollution, climate change
trophic cascade impacts
nutrients control primary productivity, fish can cause algal biomass to deviate
trophic cascade
effects of higher trophic level feeding cascades down food web
trophic dynamics govern…
the movement of nutrients and energy among organisms
confined channels
small/no flood plain, reduced sediment recruitment
unconfined channels
connected to/moving across flood plain, mobile/erodible substrates
large rivers/vast floodplains
dynamic/constantly changing, flooding can cover a significant part of the landscape, can be measured in tens of kilometers
autochthonous inputs
algae, mosses, vascular macrophytes (rooted plants)
allochthonous inputs
leaves/needles, wood, fine particulate matter, organisms that fall into the water
Baxter et al.
food webs connect terrestrial and aquatic systems. studied by separating aquatic and terrestrial systems → no bugs went in and no bugs left → spiders went hungry and increased algal blooms
discharge
volume of water passing an area per unit time
discharge equation
Q = VA
rating curve
an empirical relationship between river stage and discharge
slug injection method
using conservative tracers and advection/dispersion
factors controlling discharge (Q)
precipitation, drainage basin area, geology, soils, impervious cover, and disturbance
lag time
precipitation events and stream flow responses are always separated in time and space
hydrograph
continuous record of discharge (Q) over time
impervious cover
flashy systems, higher flow rates, less infiltration
steady state
inputs equal outputs (level of water stays the same)
residence time at steady state equation
size of pool/input or output rate
groundwater equation
GW=(DW + SR) - (trib 1 - trib 2) = ? m^3s^-1 or X% of inputs
land cover
the physical characteristics of the land surface, such as agriculture, forest, or concrete
land use
activities taking place on land, such as growing food, cutting trees, or building cities
US forests
most old growth harvested by 1920s, then began major reforestation during the 20th century.
mollisols
best for agriculture, grassland soils
ewing et al.
Cyanobacteria (nitrogen fixating) gets worse with hotter temps in eutrophic lakes, climate and atmospheric disposition affect water quality globally, land change affects water quality locally, cyanobacteria grows in sediment and brings up phosphorus from the bottom which drives nutrients in phosphorus limited lakes