Soils Final Flashcards
2 classes of organic contaminants
Industrial
Pesticides
Xenobiotics
Artificially produced organic compounds
7 possible fates of xenobiotics when released into the soil environment
Vaporize Absorbed by soil Leach down Break down into other compounds Broken down to simple products via microbe ingestion Erosion losses Taken up by plants
Remediation of contaminated soil 5 basic ways
Ex. Situ In situ Bioremediation Biostimulation Phytoremediation
Ex. Situ
Dig up, haul off, and replace or remove soil
In situ
On site remediation. Method when can’t remove the soil
Methods of in situ remediation
Decontamination
(Put down chicken litter)
Soil sequestered
(Treatments in the soil until contaminants are broken down
Surfactants
Help dissolve and disassociate some xenobiotics. Used in soil sequestering
Bioremedition
Use of organisms to remove or neutralize pollutants fro contaminated site
Do things to enrich the soil in situ
Biostimulation
Do things to increase biological activity in soil such as lime or fertilizer
Phytoremediation
Use plants to remediate soil. Take up and break down compounds
Problems with land applications of sewage sludge
sludge has contaminants such as xenobiotics and heavy metals (Cd, Ar, Pb)
2 basic types of land fills
natural, unsecured
contaminant, secured
natural , unsecured landfill structural characteristics
flat grounds
doesn’t flood
clay sublayer with a loamy topsoil
contaminant, secured landfill structural characteristics
excavated out
lined with a heavy vinyl or concrete
wells that go down into the pit
constantly check levels of dangerous contaminants
Soil properties favorable for landfills
depth 1.5 meters or more
CEC thats high with good microbe environment
soil texture that’s loamy on top and clay underneath
Problem of radon gas from soils
causes lung cancer
Cause of radon gas
emission from some soils such as shale
potential radon problem soils
highly deformed metamorphic residium soils
marine sediments
certain limestones
coal or oil bearing shales
remediation idea of radon exposure
seal cracks in foundations
houses with crawl spaces rather than slab or basement
good ventilation
fauna
soil animals
flora
soil microplants and microorganisms
5 classes of soil organisms
macrofauna mesofauna microfauna macroflora microflora
macrofauna examples
mice
moles
beetles
termites
mesofauna examples
mites
springtails
pot worms
microfauna examples
nematodes
amoebae
flagellates
macroflora
feeder roots of higher plants
mosses
microflora
root hairs algae fungi bacteria actinomycetes cyanobacteria
Things that affect soil organisms
nitrification denitrification mineralization soil aggregation water infiltration increased carbon
2 main groups of soil organisms based on where they get C
autotrophic
heterotrophic
autotrophic
“self feeding”
photoautotrophs- obtain energy from CO2 fixation
chemoautotrophs- N, S, Fe fixation
heterotrophic
cannot fix carbon and use organic carbon for growth
Primary benefits of soil organisms
organic matter decomposition
nutrient mineralization
breakdown, detoxifying pesticides and other deadly compounds
improving soil structure, erosion resistance, aeration
help plants obtain nutrients
Relative rates of organic matter decomposition
sugars/starches > proteins > cellulose > fats/waxes > lignin/cutin
Breakdown of plant debris (detritus)
- main concern: primary consumers: bacteria, fungi, shredders (mites, earthworms, etc)
- Secondary consumers: microflora and carnivores (mites, centipedes that consume small insects and nematodes)
- Tertiary consumers: ants, scorpions, birds, etc that consume soil macrofauna
decomposition of plant residue
role of residue composition
limit of C/N ratio or residue before potential for temporary tie up of soil N (25/1)
conditions affecting growth and populations of soil microorganisms
soil organic matter (detritus, humus) oxygen moisture temperature pH, CEC, Na etc
practices to increase biodiversity and populations of soil organisms
cover crops reduce tillages crop rotation with legumes liming acidic soils irrigation good soil fertility program soil erosion control
