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3/29/2020 Soils and Chemical Pollution (Chapter 18) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403451/View 1/7

Soils and Chemical Pollution (Chapter 18) Notes

Soils and Chemical Pollution (Chapter 18) Notes

Did you know .... Did you know that microorganisms can serve as powerful remediators of environmental disasters? Chapter 18 focuses on soils and chemical pollution including the use of microorganisms in bioremediation efforts.

Lecture content notes are accompanied by videos listed below the notes in each submodule (e.g. Soils and Chemical Pollution (Chapter 18) Videos A thru D). Print or download lecture notes then view videos in succession alongside lecture content and add additional notes from each video. The start of each video is noted in parenthesis (e.g. Content for Video A) within each lecture note set and contains lecture content through the note for the next video (e.g. Content for Video B).

Figures and tables unless specifically referenced are from the course text, Nature and Property of Soils, 14th Edition, Brady and Weil.

Content Video A

Soils and Chemical Pollution

Xenobiotics Xenobiotic – artificially made

“xeno” – strange

Industrialized Nations – everywhere

Pesticides – chemicals designed to kill pests

AGRI1050R50: Introduction to Soil Science (2020S) LH

3/29/2020 Soils and Chemical Pollution (Chapter 18) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403451/View 2/7

Plant protection

Pros

Reliable Food Production

Public Health

Reduce Tillage

Cons

Non-Target Injury

Water Contamination

Pesticides Most are ‘organic’ (Figure 18.1)

Carbon backbone with various structures (rings and chains)

Often include Halogen – Cl, F, Br

Insecticides – target insects

Chlorinated Hydrocarbons – DDT

Organophosphates

Carbmanates

Fungicide – target fugal pathogens

Herbicides – target plants

Thousands of formulations

Triazines

Urea-based

Pesticide Use in the U.S.

http://www.ers.usda.gov/amber-waves/2014-june/

3/29/2020 Soils and Chemical Pollution (Chapter 18) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403451/View 3/7

http://www.ers.usda.gov/amber-waves/2014-june/

Content Video B

Industrial Organic Contaminants Industrial use products

Petroleum products, solvents, hydraulic fluids, lubricants, preservatives, etc. Polycyclic Aromatic Hydrocarbons (PAH) Polychlorinated Biphenyl (PCB)

Accident and Neglect Legacy Issues Superfund Sites

Behavior in Soils

3/29/2020 Soils and Chemical Pollution (Chapter 18) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403451/View 4/7

Behavior in Soils Volatilization – gaseous loss Sorption to soil colloids Leach – Movement to groundwater Chemical Reactions – Sunlight too Microbial Degradation Runoff Loss Crop Uptake

Persistence

Pesticide Effects Soil Organisms Microbial population pretty resilient

Most do not kill broad range microbial population Shifts in community composition

Earthworms and Larger Fauna More sensitive Mirror pesticide levels in soils – bioaccumulate

Fumigants – control nematodes Destructive to both micro and macro fauna

Content Video C

Remediation Ex-Situ – move contaminated soil offsite

Chemical or physical treatment – use elsewhere Landfill Costly

3/29/2020 Soils and Chemical Pollution (Chapter 18) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403451/View 5/7

Costly In-situ – remediate in place

Decontaminate Sequester and Stabilize

Add surfactant – Increase exchange capacity – Form Organoclays Binds compounds Fixation – Stabilizes compound in place

Bioremediation Microbial Bioremediation

Biostimulation Provide limiting nutrients Stimulate microbial population

Bioaugmentation Inoculate with consortia – known degraders

Soils and Groundwater Phytoremediation

Hyperaccumulators – accumulate contaminant, remove in biomass Enhance rhizosphere – better habitat for microbes

Content Video D

Inorganic Contamination “Heavy Metals”

Arsenic, Cadmium, Chromium, Lead, Mercury, Selenium (etc.) Toxic to humans and animals (varying levels)

Industrial Activities Fossil fuel emissions, smelting, industrial waste, municipal solid waste Sewage Sludge

Metals – cannot degrade – accumulate in soils Bioaccumulate – soils/air/water to plants to animals/humans

Prevention of Inorganic Contamination Reduce load Immobilize metals in soil

Maintain near-neutral pH – less available Promote good drainage – oxidized metals less problematic

Utilize phytoremediation Hyperaccumulating plants Remove biomass – remove metals from system

Landfills

3/29/2020 Soils and Chemical Pollution (Chapter 18) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403451/View 6/7

Radon Gas and Soils Radioactive gas – radioactive decay of uranium Highly toxic to humans – Long term exposure cancer Uranium rich parent materials soils Problematic in buildings – comes up from soil and is drawn in through cracks and diffusion Test issues

Seal off basement Increase ventilation

Radon in TN

http://health.state.tn.us/environmental/radon.htm#radon2

3/29/2020 Soils and Chemical Pollution (Chapter 18) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403451/View 7/7

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