Environmental Science 105 Test 2

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