Soil Contamination

and Remediation

Michal Sněhota - B680

Martin Šanda - B673

martin.sanda@fsv.cvut.cz

Conditions for credit

A) Presence at lectures (3x missing allowed)

B) Presence and activity in one (only) lab

C) Submission of the final lab report (digital only, doc, docx, pdf) on

martin.sanda@fsv.cvut.cz

Lab

porous media column contamination and decontamination

calculation of the experiment, report with figures and conclusions

Lectures posted on the webserver of Dept.143:

http://storm.fsv.cvut.cz/ Přednášky on-line

Exam is taken without notes, calculators, cell phones computers etc. Pre-printed

questions are given

Exam is written – max of 2hrs

Exam consists of 8 questions (10 points each) and one calculation (20 points)

of total 100 max.

Classification ECTS A B C D E F

Points 100-90 89-80 79-70 69-60 59-50 < 50

Relative to old system 1,0 1,5 2 2,5 3 4

Requirements for the exam

Introduction to

Soil Contamination and

Remediation

• importance of soil, soil formation

• soil substances, water in soil

• terminology, classification

List of topics

Introduction to soil science, soil formation; soil properties

Introduction to soil chemistry; chemical reactions in soil

History of soil contamination and remediation; impacts of contaminants on

the environment and health

Contaminants transport and fate; experiments and analytical detection

methods

Types of contaminants

Site survey, field methods of contaminants detection

Soil remediation methods: Pump-and-treat Systems, Solvent Vapor

Extraction, Air Sparging, Soil Flushing

Migration Covers, Cut-off Walls, Solidification / Stabilization

Reaction barriers: Funnel and Gate Systems, Permeable Treatment Walls

Natural Attenuation; new methods of soil remediation

Bioremediation, fytoremediation

Lab of contamination and remediation

Lab protocol preparation

Exam

Soil – interface of systems

soil is natural unit generated

at the interface of

lithosphere and atmosphere

under mutual process of

pedogenetic factors

soil is binding element in

between anorganic and

organic matter and live

organisms on the Earth

soil is desribed according to

soil horizons

hydrosphere

+

atmosphere

pedosphere

Soil

Atmosphere Vegetation

Bedrock

Weathering

Nutrient release

Fertility

Texture

Colour

looseningporesNutrients

Water

pH

Carbon binding

Roots

Nutrients

Organic matterCO2

H2O

Wind

Heat

Rain

Light

Soil profile –

vertical

section

combining

all soil

horizons

Soil horizon

designations

layers with

properties

different from

other adjacent

layers

Basic nomenclature

litter layer

A (humus)

B (leached)

C (bedrock

substrate)

R (bedrock)

Ecological functions of soil

• Supports growth of plants and live of

other organisms (phytoedaphon and

zooedaphon)

• Recycles nutrients and exhausts

• Governs flow and purity of water

• Serves as building material

Minerals

• Composed of O,Si, Al – nearly 90% of solid soil mass

• Up to 50% of soil volume

• Made of particles of different sizes

• Determine chemical reaction

• Originate from bedrock material

Pedogenetic factors

• Bedrock(determines properties of soils, important is ability of rock to weather)

• Topography (steepness, orientation, altitude)

• Climate (moisture and temperature, precipitation - rainfall)

• Organisms(determine creation and existence of soil)

• Time

granite

40cm

A

Bw

C

slate

1.5m

A

AB

C

Bss1

Bss2

fine

dark

coarse

light

Impact of bedrock at soil genesis

Impact of climate at soil genesis1. Temperature

2. Rainfallannual distribution of rain

topography

vegetation cover

permeability

limestone +

dry climate

40cm

A

R

limestone +

wet climate

60cm

A

B

C

rainforest,

tropical

warm, wetArid,

semi-

arid

Desert,

perma-

frost

10cm 1m >1m 15m

Impact of climate to soil layering

A

C

B

A

C

R

B

A

C

R

B

A

C

R

Weatheringphysical

1. Frost

2. Irregular heating

3. Swelling - drying

4. Abrasion (water, wind, ice)

5. Root growth

1. Hydratation

2. Hydrolysis

3. Dissolution

4. Carbonation

5. Complexation

6. Oxidation-reduction

Water is necessary

in all of the chemical

reactions!!!

WeatheringChemical

Impact of organisms on the

soil formation

• Vegetation

–

• Microbes

–

• Soil animals

• Humans

Type of rooting, leaf chemism, amount

Decomposition of the organic matter

- Building of pathways for water flow

Tillage, compaction, changes of the

landscape – drainage, aplication of

chemicals, pollution

phyto- a zoo-edaphon - examples

mites

actinomycetes

vertebratesworms

bacteriafungi

protozoa

•intensive

agriculture✓fertilization

✓pesticides

✓toxic compounds

•landfills

•urbanization

•deserti-

fication

•erosion

✓forest clear-

cutting

✓agriculture

Human impact on soils

natural plants, agriculture crops:

fields, meadows, pastures, forests

trees – forests, rainforests

Vegetation

Time development

of the soil profile

“highly

mature

profile”

“mature

profil”

“young

profile”

maternal

bedrock

1m>1m

15m

C

C

A

C

A

Bw

C

A

Bt1

Bt2

Soil texture and soil structure

aggregates – spatial

composition

texture – %clay, silt, sand

determined, can not be

changed

chemical bonds of humus units

at the clay minerals can be

changed (good/bad)

texture classes soil types

Texture and structure are parameters of

plynná

fáze -

půdní

vzduch

pevná

fáze -

minerály

kapalná

fáze -

voda

pevná

fáze -

organická

hmota

`

soil solids

texture relates to

mineral part of

solid phase only

structure is

dependent on

mineral and

organic part of

solid phase – very

important for

binding pollutants

gaseous

phase

soil air

liquid

phase

soil

water

solid

phase -

organic

matter

solid

phase –

minerals

Bulk and particle density

Macroscopic characteristics of solid phase

pores

solid

phase

volume of pores =

Vp

vol. solids = VS

To

tal v

olu

me

= V

weight of solids = ms

rd = [M/ L3]ms

V

Bulk density

rs = [M/ L3]ms

Vs

Particle density

V = Vs + Vp

Bulk and particle densityMacroscopic characteristics of solid phase

texture categoriesgravel, sand, silt, clay

determined as differences % of weights of grain size intervals

jíl

<0.002 mm

písek

0.063(0.05)

-2 mm

štěrk

> 2 mm

prach

0.002-

0.063(0.05)

mm

`

silt

sand

clay

gravel

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10 100

D [mm]

W [

%]

Particle size distributiondescribes weights and grain sizes (indirectly pore sizes)

cumulative property– weight fraction of the whole sample

where all grains are smaller than diameter D

gravelsandsiltclay

Texture classes according to clay, silt, sand

Triangle diagram of soil texture (NRSC USDA)

Grain size and particle surface

area• area of grain surface at unit wight

– 1 g sand ~ 0.1 m2

– 1 g silt ~ 1 m2

– 1 g clay ~ 10-1000 m2

•

•

smallest

largest

higher surface area – higher electrical charge for attraction of

water, nutrients, contaminants

coarse soils have bigger pores – but lower porosity (0.3-0.5)

fine soils have smaller pores – but higher porosity (up to 0.7)

Fine clay

surface area is

approx

~10000x higher

than medium

coarse sand of

of the same

weight

Soil structure

• primary spatial constellation of soil into clumps

called aggregates or pedons

• binding factors are plant root (their excrements),

organic matter and clay minerals,

• sandy and rocky soils do not create aggregates

• most important factor of aggregation is organic

matter

• stability of aggregate is their endurance towards

breakdown under external impacts

Characteristics of soil

structure

• Type: Shape of aggregates

crumbs, blocky, prizmatic, platy..

• Size:

– fine (microaggregates) <0.25 mm

– coarse (makroaggregates) >0.25 mm

• Degree of structure:

– without st., weak st., highly developed st.

• General

– lots of clay strong structure, big blocks

– lots of organics crumbly structure

impact of roots on soil stability

Sulzman

Tomášek, M; Atlas půd České Republiky ČGÚ, Praha 1995

Classes of soil structure

crumbs polyedricI. II.

Tomášek, M; Atlas půd České Republiky ČGÚ, Praha 1995

blocky

II.

III.

III.

IV.

prizmaticplaty

Classes of soil structure

Soil water

• Necessary for plant growth

• Basic medium for transport of matter

• Basic media for clean up of soil

• Is found in soil as– chemically bound and

hygroscopic (grain wrap),

– capillary (capillary forces in pores)

– gravitational (temporal, outflows after cessation of the water source- rain, flood, snowmelt)

Dipoleextremely good solvent

Water in soil

moisture of porous media

solids

poresair

water

Water in soil

water content, moisture

solids

poresair

water

Va

Vw, mw

Vs, ms

Vp

w = [-]mw

ms

gravimetric water content

q - volumetric water content

q = [-]Vw

V

Relation between w and q

w . rd = q . rw

w . rd

rw

q =

for rw = 1 g/cm3:

q = w . rd

Capillarity

modfifed from Hotron and Jury 2004

At the planar interface

water-gas, the pressure

is pr

pr

At the curved interface

the pressure is p = pr

ps

For spherical surface additional (capillary)

pressure ps causes the curvature:

ps =2s

R

Capillarity

modified from Kutílek a kol. 1994

At the interace water-gas-solid

contact angle g occurs

g

g g =

0

g

g

g

ideal wetting wetting non-wetting

in multiphase systems (water-oil-gas-solid – more combinations of fluid behaviour)

Retention curve of soil moisture

•soil system of pores can be ideally substituted by the bundle of

capillary tubes of different diameters

•applying suction of equivalent suction head hi all tubes thicker than ri

diameter are drained, thinner than ri stay filled with water

hi

ri

w

(kPa)

qv (%)

0

-10

-100

-103

-104

-105

0 10 20 30 40 50 60

Retention curve of soil moisturetransfers soils suction into moisture – bulk water content

bulk water content

so

il suction

it is series of equilibrium of

water content in the soil

sample are relating soil

suction (capillary potential)

Drainage branch of the retention curve-

sand tank

for suction of 0-100

(max.200) cm - of the water

column, limited by room

dimension (height),

theoretically limited by 1 Bar

(approx 10 m of suction)

h

open container

free water

level water table

difference

causes suction

in the clay tank

Drainage of the retention curve –

pressure chamber

for suction 100-15000 cm

(0.01-1.5 MPa, 0.1-15 Bar)

water dripping

SOIL CORES

PRESSURE

TANKPRESSURE

TANK

REDUCTON

VENTS,

MANOMETER

COMPRESSOR

Methods of soil moisture measurement

Direct method

Gravimetric

Potential methods

Resistivity

Tenzometric

Electromagnetic methods

Frequency domain reflectometry

Time domain reflectometry

Radiometric methods

Neutron, Gamascopic

Satellite methods

Saturated flow

Darcy, H., 1856. Les Fountaines de la Ville de Dijon

Henry Darcy (1856) solved the filtration

problem for fountains in Dijon.

He found that flow of water through the

column of sand is dependent:

•proportionally to the difference of hydrostatic

pressure at the ends of the column

•improportionally to the length of the column

•proportionally to the cross-section of the

column

• depends on the coefficient for the given

material

Henry Darcy

Darcy’s law

Q = flow of water per unit time [L3.T-1]

A = flow area perpendicular to flow [L2]

Ks = saturated hydraulic conductivity [L.T-1]

rH/L = hydraulic gradient

valid in fully

saturated area -

aquifer

L

ΑΔΗΚQ S

LH2

H1

datum

z1

z2

h1

h2

Hi = hi+zi

Measurements of Ks

Experiments with constant gradient

Saturated hydraulic conductivity - Ks

units of Ks [ L.T-1] frequently (m.s-1), (cm.d-1), (cm.s-1)

Ks characterizes water-soil relation

r soil propeties only:

k = Ksn [ L2] freequently (m2), (cm2)

n is kinematic viscosity (of the fluid)

Permeability - k

Darcian velocity – averaged velocity per whole cross-sectional area

of the sample

Mean pore velocity – averaged velocity per pore cross-section only

Preferential flow velocity – velocity due to preferential pathways –

flow through fraction of the area, velocities in orders of magnitude

higher than Darcian velocity

Saturated hydraulic conductivity Ks and

permeability scale

k(c

m2)

K(c

m.s

-1)

K(m

.s-1

)Císlerová a Vogel, 1998

cla

y

sil

t

silt-

san

d

san

d

gra

vel

Function of the unsaturated

hydraulic conductivity

Function of the

unsaturated

hydraulic

conductivity K(q) –

part of the pores is

saturated with

water, part if filled

by air

K(q)=Ks. Kr (q)

qs – saturated

water content

Průběh hydraulické vodivosti podle vlhkosti

0

1

2

3

4

5

6

7

8

9

10

0.5 0.55 0.6 0.65 0.7

objemová vlhkost (-)

hy

dra

ulic

ká

vo

div

os

t (L

/T)

funkce nenasycené hydraulické vodivosti

Ks - nasycená hydraulická vodivost

Ks

qs

function of unsaturated hydr.conductivity

Ks – saturated hydraulic conductivity

volumetric water content (-)

hyd

rau

lic

co

nd

uti

vit

y (

L/T

)

Measurement of the unsaturated hydraulic

conductivity in field

Global soil regions

US –Soil Taxonomy USDA

European soil regions

ReferencesKutílek, M., Kuráž, V., Císlerová, M. Hydropedologie, skriptum ČVUT 1994

Fitzpatrick, Soils: Their formation, classification and distribution

Sulzman E.W. : CSS 305 Principles of Soil Science: http://cropandsoil.oregonstate.edu/classes/css305/lecture_sched.html

Departamento de Edafología y Química, Agrícola Universidad de Granada,España Unidad docente e investigadora de la Facultad de Cienciashttp://edafologia.ugr.es/

Tomášek, M. Atlas půd České republiky, ČGÚ 1995.

http://eusoils.jrc.it/Data.html Soil & Waste Unit, European Communities –soil maps

FAO World reference base for soil resourceshttp://www.fao.org/documents/show_cdr.asp?url_file=/docrep/W8594E/W8594E00.htm