MASSA Spin-off – Riduzione dei rischi ambientali
Claudio Lubello
University of Florence (Italy)
Sao Paulo, Brasil, Decembre 2011
MASSA Spin-off – Riduzione dei rischi ambientali
Universidade de Florença
Atualmente é uma das maiores organizaçoes de pesquisa e formaçao
superior na Itália, com 2.300 docentes e pesquisadores, mais de
1.400 doutorandos de pesquisa e 60.000 estudantes.
MASSA Spin-off – Riduzione dei rischi ambientali
Conselho Nacional de Pesquisas
CNR
Ente público nacional responsável pela produçao,
promoçao, difusao, transferência e valorizaçao das
atividades de pesquisa e respectivas aplicaçoes
para o desenvolvimento do país.
11 Departamentos
Mais de 100 Institutos
MASSA Spin-off – Riduzione dei rischi ambientali
M.A.S.S.A. Spin-off
Metodologias e Aplicações Científicas para a
Salvaguarda Ambiental
 Oferecer soluçoes para mitigaçao dos impactos ambientais.
CNR – Conselho Nacional
de Pesquisas
UNIFI – Universidade de
Florença
MASSA Spin-off
Parceiros Industriais
Sócios Privados
MONITORAMENTO DE RISCOS
MASSA Spin-off – Riduzione dei rischi ambientali
European directive
Member States shall take appropriate measures to
encourage:
(a) firstly, the prevention or reduction of waste production
and its harmfulness,
(b) secondly:
- the recovery of waste by means of recycling, reuse or
reclamation or any other process with a view to extracting
secondary raw materials, or
- the use of waste as a source of energy.
MASSA Spin-off – Riduzione dei rischi ambientali
Waste hierarchy
Reduce
Reuse
Recycle
Energy
Recovery
Landfilling
MASSA Spin-off – Riduzione dei rischi ambientali
Landfills
The European Union has laid down strict requirements for
landfills to prevent and reduce as far as possible the
negative effects on the environment, specifically on surface
water, groundwater, soil, air and human health.
Stringent operational and technical requirements on the
waste and landfills
MASSA Spin-off – Riduzione dei rischi ambientali
Municipal waste production
900
800
700
kg/capita/year
600
500
400
300
200
100
0
Municipal waste production (kg/capita/year) Eurostat 2008
MASSA Spin-off – Riduzione dei rischi ambientali
Municipal waste recycled
50
45
40
35
30
25
20
15
10
5
0
Municipal waste recycled (%) - Eurostat 2008
MASSA Spin-off – Riduzione dei rischi ambientali
Municipal waste incinerated
60
50
40
30
20
10
0
Municipal waste incinerated (%) - Eurostat 2008
MASSA Spin-off – Riduzione dei rischi ambientali
Landfills are still present
MASSA Spin-off – Riduzione dei rischi ambientali
Municipal waste landfilled
100
90
80
70
60
50
40
30
20
10
0
Municipal waste landfilled (%) - Eurostat 2008
MASSA Spin-off – Riduzione dei rischi ambientali
Even if people don’t like them…
MASSA Spin-off – Riduzione dei rischi ambientali
…Sanitary landfills are much better then uncontrolled
disposal
MASSA Spin-off – Riduzione dei rischi ambientali
CONTROL AND MONITORING PROCEDURES IN
OPERATION AND AFTER-CARE PHASES
To be carried out in order to verify:
that the waste accepted to disposal meets the criterias
established for the landfill category,
that the processes undertaken within the landfill are correct,
that the environmental protection systems function fully as
intended,
that the permit conditions for the landfill are fulfilled.
MASSA Spin-off – Riduzione dei rischi ambientali
How is a landfill made…
MASSA Spin-off – Riduzione dei rischi ambientali
Technical features
3 type of landfills
(a) excavated trench
(b) area
(b)
(c) canyon/depression
(c)
MASSA Spin-off – Riduzione dei rischi ambientali
Chemical, Physical and Biological processes
inside municipal landfill
Municipal waste degradation produce leachate and biogas,
main landifill vectors of environmental pollution.
Leachate
Liquid mixture caused mainly by
water percolating through waste
deposited in a landfill. Once in
contact with decomposing solid
waste, the percolating water
becomes contaminated.
Biogas
Gas produced by the biological
breakdown of organic matter. Biogas
comprises primarily methane (CH4)
and carbon dioxide (CO2).
MASSA Spin-off – Riduzione dei rischi ambientali
Preparation of the site for landfilling
Existing site drainage must be modified to route any runoff
away from the area.
Excavation and preparation of the landfill bottom and
subsurface sides. Geomembrane liners are installed.
MASSA Spin-off – Riduzione dei rischi ambientali
Preparation of the site for landfilling
Leacheate collection and extraction facilities are placed within or on the
top of the liner.
Horizontal gas recovers trenches may be installed at the bottom of the
landfill.
Before the fill operation begins, a soil berm in constructed at the
downwind side of the planned fill area. The berm serves as a windbreak to
control blowing materials and as a face against which the waste can be
compacted
MASSA Spin-off – Riduzione dei rischi ambientali
Preparation of the site for landfilling
MASSA Spin-off – Riduzione dei rischi ambientali
MASSA Spin-off – Riduzione dei rischi ambientali
Phase I. Initial adjustment phase
The organic biodegradable components in MSW undergo
microbial decomposition as they are placed in a landfill and
soon after.
Biological composition occurs under aerobic conditions,
because a certain amount of air is trapped within the landfill.
The principal source of microrganisms is the soil material used
as a daily and final cover.
Digested wastewater sludges and recycled leachate are other
sources of organisms.
MASSA Spin-off – Riduzione dei rischi ambientali
Phase II – Transition phase
• Oxygen is deplated and anaerobic conditions begin to
develop.
• Nitrate and sulphate are often reduced to nitrogen gas and
hydrogen sulphide.
• The onset of anaerobic conditions can be monitored by
measuring the oxidation/reduction potential of waste.
• The pH of leachate starts to drop due to the presence of
organic acids and the effect of high CO2 concentrations
within the landfill.
MASSA Spin-off – Riduzione dei rischi ambientali
Phase III: Acid phase
• First step: Enzyme mediated transformation (hydrolis) of
higher molecular mass compunds (lipids, polysaccharides,
proteins and nucleic acids) into compounds suitable for use
by microrganisms as a source of energy and cell carbon;
• Second step: Microbial conversion of the compounds
resulting from the first step into lower molecular mass
intermediate compounds (typified by acetic acid: CH3COOH).
Carbon dioxide is the principal gas generated.
• The pH of the leachate will often drop to a value of 5 and
lower. The BOD and COD and the conductivity of the
leachate will encrease significantly. If leachate is not
recycled , the essential nutrients will be lost from the system.
MASSA Spin-off – Riduzione dei rischi ambientali
Phase IV: methane fermentation phase
A second group of microrganisms which converts the
acetic acid and hydrogen gas to CH4 and CO2,
becomes predominant. They are identified as
methanogens or methane formers.
The pH will rise to more neutral values in the range of 6.8
to 8. The COD and conductivity value of the leachate
will be reduced. With higher pH values, fewer inorganic
constituents can remain in solution.
MASSA Spin-off – Riduzione dei rischi ambientali
Phase V: Maturation phase
The maturation phase occurs after the readily available
biodegradable organic material has been converted to CH4
and CO2. The rate of landfill gas generation diminishes
significantly. The substrates that remain in the landfill are
slowly biodegradable. During maturation phase, the leachate
will often contain humic and fulvic acids, which are difficult to
process further biologically.
MASSA Spin-off – Riduzione dei rischi ambientali
MASSA Spin-off – Riduzione dei rischi ambientali
Quality and quantity of biogas and leachate
result from numerous elements
Environmental
characteristics
Rainfall
Air temperature
Air Umidity
Wind
Waste characteristics
Density
Pre-treatments
Waste Umidity
Waste product analysis
Waste granulometry
Landfill
Type and geometry
Coverage materials
Biogas and leachate drainage
techniques
MASSA Spin-off – Riduzione dei rischi ambientali
Typical constituents found in MSW
landfill gas
Component
Percent (dry volume)
Methane
45-60
Carbon dioxide
40-60
Nitrogen
2-5
Oxygen
0.1-1.0
Sulfides, Disulfides, Mercaptans, etc.
0-1.0
Ammonia
0.1-1.0
Hydrogen
0-0.2
Carbon monoxide
0-0.2
Trace constituents
0.01-0.6
MASSA Spin-off – Riduzione dei rischi ambientali
Typical data (mg/l) on the composition of leachate
Constituent
New landfill
(<2 years)
Mature landfill
(> 10 years)
BOD5
10.000
150
COD
18.000
300
TSS
500
250
Organic Nitrogen
200
100
Nitrate
25
10
Total phoshorous
30
10
3.000
600
6
7
500
250
Alkalinity as CaCO3
pH
Chloride
The presence of trace compounds (some of which may pose high health risks) will depend on the concentration
of these in the gas phase within the landfill
MASSA Spin-off – Riduzione dei rischi ambientali
Biogas and Leachate control
Biogas – It is necessary to monitor diffusion from the
capping system in order to identify the more critical
areas.
Leachate – It is necessary to verify the risk of
groundwater pollution due to leakages.
MASSA Spin-off – Riduzione dei rischi ambientali
Leachate monitoring
MASSA Spin-off – Riduzione dei rischi ambientali
Chemical parameters to be controlled
Italian Law requires:
pH, Temperature, Conductivity, Oxidability (Kubel), BOD5, TOC,
COD, Ca, Na, K, Chlorides, Sulphates, Fluorides, IPA,
Metals, Cyanides, Nitrogen compounds, Organoalogen
compounds, Pesticides, Phenols, Solvents.
Often what Regulations ask is not sufficient to identify a
possible dangerous mixing between natural water and
leachate.
MASSA Spin-off – Riduzione dei rischi ambientali
Isotopes
Isotopes are variants of atoms of a particular chemical element, which have
differing numbers of neutrons. Atoms of a particular element by definition
must contain the same number of protons but may have a distinct number of
neutrons which differs from atom to atom, without changing the designation
of the atom as a particular element. The number of nucleons (protons and
neutrons) in the nucleus, known as the mass number, is not the same for two
isotopes of any element. For example, hydrogen-1, hydrogen-2 (Deuterium)
and hydrogen-3 (Tritium) are three isotopes of the element hydrogen with
mass numbers 1, 2 and 3 respectively. The atomic number of nitrogen is 1
(every hydrogen atom has 1 proton); therefore the neutron numbers in these
isotopes are 0, 1 and 2 respectively.
MASSA Spin-off – Riduzione dei rischi ambientali
Leachate isotopic monitoring
Leachate and Natural water have different isotopic
characteristics, which can led to different concentrantions
of some species by more than 2 orders of magnitude.
In a landfill monitoring system, isotopes can be used a tracer
of water pollution due to leachate mixing.
MASSA Spin-off – Riduzione dei rischi ambientali
Principal isotopic parameters
18O/16O
2H/1H
3H/H
Isotopic ratio as regards a standard in term of ‰ (per mil)
‰ = [ (Rcp/Rst) –1 ]*1000
Rcp and Rst are isotopic ratios (18O/16O, 2H/1H). Rcp refers to the sample while Rst
refers to the standard V-SMOW (Vienna Standard Mean Ocean Water).
Isotopic contents of hydrogen radioactived (3H). It is expressed in term of absolute
concentrantion U.T. (Tritium Unitiy; 1 U.T. is equivalent to one atom of 3H for every
1018 atoms of H, equivalent to a radioactiviy of 0,12 Bq/l).
13C/12C
Isotopic ratio of dissolved inorganic carbon (DIC). It is expressed in term of ‰ as to
the standard PDB (Pee Dee Belemnitella, South Carolina/USA carbonatic rock)
MASSA Spin-off – Riduzione dei rischi ambientali
WORLD RAINFALL LINEAR
REGRESSION
Craig, 1961 – con modifiche
MASSA Spin-off – Riduzione dei rischi ambientali
LEACHATES
COMING FROM
ANAEROBIC
DEGRADATED
ORGANIC WASTE
2H
and 18O
COMPARISON BETWEEN
RAINFALL WATER AND
LEACHATE
MEDITERRANEAN
RAINFALL LINE
WORLD RAINFALL
LINE
MASSA Spin-off – Riduzione dei rischi ambientali
Concentration of TRITIUM (3H) in Italian rainfall water
1000
U.T. Piogge Genova proiettate al 2006
U.T. Piogge Pisa proiettate al 2006
ESPLOSIONI TERMONUCLEARI
IN ATMOSFERA
U.T.
100
10
1
1950
1960
1970
1980
1990
2000
Anno
MASSA Spin-off – Riduzione dei rischi ambientali
Concentration of TRITIUM (3H) in Italian rainfall water
1000
U.T. Piogge Genova proiettate al 2006
U.T. Piogge Pisa proiettate al 2006
ESPLOSIONI TERMONUCLEARI
IN ATMOSFERA
LANDFILL LEACHATE 3H
CONCENTRATION FREQUENTLY
100
RANGES FROM 200 AND 1500 U.T.
U.T.
SOMETIMES IT CAN ACHIEVE MORE
THAN 3000 U.T.
10
1
1950
1960
1970
1980
1990
2000
Anno
MASSA Spin-off – Riduzione dei rischi ambientali
Concentration of TRITIUM (3H) in Italian rainfall water
1000
U.T. Piogge Genova proiettate al 2006
U.T. Piogge Pisa proiettate al 2006
ESPLOSIONI TERMONUCLEARI
IN ATMOSFERA
LANDFILL LEACHATE 3H
CONCENTRATION FREQUENTLY RANGE
100
FROM 200 AND 1500 U.T. SOMETIMES IT
U.T.
CAN ACHIEVE MORE THAN 3000 U.T.
10
THIS CLEAR DIFFERENCE ALLOW TO FIND OUT LOW WATER
CONTAMINATION FROM LEACHATE
(EVEN LESS 1% OF LEACHATE)
1
1950
1960
1970
1980
1990
2000
Anno
MASSA Spin-off – Riduzione dei rischi ambientali
TRITIUM versus CHLORIDES
TRIZIO VS. CLORURI
TRIZIO VS. CLORURI
1,000
10000
1000
trizio (U.T.)
trizio (U.T.)
100
10
100
10
percolato
1
10
100
cloruri (mg/l)
percolato
1,000
1,000
percolato
LEACHATE
punti
d'acqua
1,000
1,000
10,000
TRIZIO VS CLOR
1
10
1,000
percolato
TRIZIO VS CLORURI
GROUNWATER
punti d'acqua
SAMPLE
100
punti d'acqua
punti d'acqua
Curve che delimitano il
campo di potenziale
campo di potenziale
mescolamento
mescolamento
Curve che delimitano il
1000
cloruri (mg/l)
TRIZIO VS CLORURI
Curve
che delimitano
POTENTIAL
MIXING il
campo
di potenziale
CURVES
mescolamento
TRIZIO VS CLORURI
Curve100
che delimitano il
(U.T.)
1
10000
MASSA Spin-off – Riduzione dei rischi ambientali
CARBON ISOTOPE
13C‰
GROUNDWATER
LEACHATE
Range from - 25 and 0
Range from +15 and +30
MASSA Spin-off – Riduzione dei rischi ambientali
OTHER ISOTOPES PARAMETERS
GROUNDWATER
34S‰
of dissolved
sulphate
Range from - 21 and - 8
LEACHATE
Frequently around +8
GROUNDWATER
18O‰
Range from - 0,20 and +11,40
of dissolved
LEACHATE
sulphate
Frequently around +27
MASSA Spin-off – Riduzione dei rischi ambientali
Biogas monitoring
MASSA Spin-off – Riduzione dei rischi ambientali
Air pollution control
It is really important to identify and
biogas sources inside a landfill:
• Diffuse sources from the coverage
• Gas extraction wells
• Biogas flares
• Biofilters
quantify the
A relevant part of the biogas could be diffused into
the atmosphere.
MASSA Spin-off – Riduzione dei rischi ambientali
Monitoring biogas diffusion from coverage
The CNR worked out a system to monitor gas flux from landfill coverage
on the basis of the experience used to monitor gas emission from
volcanic and geothermal areas.
MASSA Spin-off – Riduzione dei rischi ambientali
Physical laws: diffusion and advection
The gas transport phenomenon through the soil are mainly ruled by two
different mechanisms: diffusion and advection. In the geological literature
these two factors are referred to the Fick (diffusion) and to the Darcy
(advection) laws.
 Diffusion phenomenon are due to concentration gradients. In a porous
media, the diffusion process in a direction is described by Fick’s first law:
Fd = -K d (dc/dx)
Fd is the diffusion velocity in a surface unit (moli/cm2sec), K is the porosity coefficient, d is the diffusion
coefficient (cm2/sec) and dc/dx is the concentration gradient in x direction.
Advective motions are due to pressure gradients and are described by the
Darcy law: Fc = - (K/µ) (dp/dx)
Fc is the specific flow (cm/sec), K is the permeability coefficient expressed as Darcy units
[1Darcy=1cm2/(sec atm)], µ is the gas viscosity in centipoise and dp/dx the concentration gradient in x
direction.
MASSA Spin-off – Riduzione dei rischi ambientali
How to estimate the total emission
The estimation of the total amount of gas discharged at the soil-air
interface can be obtained by well distributed punctual flux measurements
carried out on all the investigated area.
Anyway there are a lot of problems concerning the single measurement
depending on the reliability of the measuring system, the influence of
the meteorological parameters (atmospheric pressure, temperature,
relative humidity), on the characteristics of the monitored soil (moist
content, presence of fracture).
Finally the choice of the right data treatment can make the difference
between reliable results and quite pure fantasy.
MASSA Spin-off – Riduzione dei rischi ambientali
Measurement techniques
There are various different systems to get soil gas flux measurements. The
principal developed techniques can be divided in three main categories:
i.
ii.
iii.
Measurements of the gas concentration gradient
Micro-meteorological techniques (e.g. eddy correlation)
Enclosure based techniques (static and dynamic accumulation chamber)
The accumulation chamber method is commonly considered superior to other
techniques such as those based on the dynamic concentration, in situ gas
concentration measurements at different depths, tracer gas, and eddy correlation.
Furthermore, Trégourès et al. (1999) demonstrated that the accumulation
chamber method is less dependent on meteorological conditions compared to the
other methodologies.
MASSA Spin-off – Riduzione dei rischi ambientali
The accumulation chamber method
The device developed by CNR,
consists of an accumulation
chamber,
two
IR
spectrophotometers to measure CO2
and CH4 concentrations, a PID
(Photoionization detectors) sensor
for VOC and a electro- chemical
sensor for H2S. The system is
completed by an analogical-digital
converter, a palmtop computer, and
a Global Positioning System (GPS).
The gas flux is proportional to the
slope of the straight line fitting the
concentration versus time curve.
Soil Surface
MASSA Spin-off – Riduzione dei rischi ambientali
Accumulation chamber: calibration
The measurements made on site, are referred to the slope of the
straight line fitting the concentration versus time curve. This data,
expressed in ppm/sec (or ppb/sec) units, are correlated to the specific
flux (e.g. mol/m2 day) of every analyzed gas, by mean of calibration
curves. Laboratory tests have to be performed before each survey in
order to get these calibration curves.
y = 4.9352x
R² = 0.9995
300.00
250.00
ppm/sec
200.00
150.00
100.00
50.00
0.00
0.00
20.00
40.00
cc/min
60.00
MASSA Spin-off – Riduzione dei rischi ambientali
Accumulation chamber: field
measurements
Although the accumulation chamber method is less
dependent on meteorological conditions, compared to
the other methodologies, some parameters may have
an influence on the gas emission at soil-air interface.
To avoid or minimize these effects, it’s important to
carry out the investigations in steady dry weather period
and completing each flux survey in few working days.
Moreover it’s important to keep under control the
atmospheric pressure and the influence of its variations
with additional measurements repeated on the same
site during all the survey period.
MASSA Spin-off – Riduzione dei rischi ambientali
The right sampling grid
To choose the proper sampling grid it’s important to have information about
the spatial characteristic of the studied phenomenon. In some case auxiliary
analysis can give a help to get the right dimensioning of sampling array.
For example in landfill biogas emission monitoring, a preliminary infrared
thermographic survey can be useful to understand the areal extension of
anomalous degassing zones.
Typically, in environmental
applications, the sampling
mesh varies from 10 to 30 m
(1 measure every 100 m2 to 1
every 900 m2).
The total number of
measurements is usually
greater than 100-150 (up to
1000)
MASSA Spin-off – Riduzione dei rischi ambientali
The sampling grid
150
149
151
148
132
152
250
264
265
249
254
253
252
251
263
321
280
277
247
281
268
245
246
285
276
243
325
272
242
241
214
240
239
202
187
200
199
178
205
177
287
289
236
332
331
291
290
342
292
168
195
232
297
337
231
0
50
100 m
308
338
296
13
14
170
194
339
335
295
298
307
229
228
305
173
71
102
101
100
98
91
97
92
93
304
225
86
99
90
174
303
226
89
104
103
87
88
74
72
70
75
73
172
306
302
227
67
106
105
85
76
65
66
68
84
77
169
301
63
5
2
82
83
78
64
4
107
81
62
7
6
3
171
299 336
230
12
16
15
8
10
11
17
27
309
20
19
18
26
169
193
24
25
28
310
108
79
9
31
30
80
109
61
23
29
167
191
340
294
233
38
110
60
21
32
37
166
111
59
22
36
40
311
334
293
234
57
58
35
39
192
141
140
112
33
42
47
165
312
196
56
34
220
341
333
235
45
41
164
197
330
50
48
219
55
44
43
313
190
176
204
288
237
189
198
51
49
163
218
142
139
114
113
124
125
188
53
52
123
128
314
201
179
329
238
217
186
180
328
315
216
143
138
115
129
127
162
215
20
206
286
316
185
181
327
274
273
126
144
137
116
122
156
318
203
207
157
155
184
182
208
326
158
145
136
117
130
154
317
213
146
135
118
121
258
259
160
319
212
183
209
284
271
320
211
324
275
283
270
260
161
134
119
131
159
210
282
269
244
323
120
153
257
322
278
279
267
256
261
262
266
248
255
147
133
96
224
223
175
222
95
94
221
0
50
100 m
MASSA Spin-off – Riduzione dei rischi ambientali
The right sampling grid
We have already seen that to get reliable estimations of global gas emission,
large datasets are needed. The bigger is the number of measurements, the
more trustworthy the evaluations are. Some tests have been done to assess
the sampling density influence on results and to find the right balance
between cost and effectiveness.
Grid dimension=chamber diameter
0.
100.
200.
300.
400.
500.
600.
700.
800.
Extraction
900.
0.
600.
600.
Colors
500.
>=4.5
3.72781
3.503
3.35355
3.18858
2.99515
2.77156
2.50076
2.39732
2.28179
2.14626
1.9534
1.72281
<0.5
500.
400.
400.
300.
300.
200.
200.
100.
0.
0.
100.
200.
300.
400.
500.
600.
700.
800.
200.
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400.
500.
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800.
0.
900.
100.
200.
300.
400.
500.
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800.
0.
900.
100. 200. 300. 400. 500. 600. 700. 800. 900.
600.
600.
600.
600.
600.
500.
500.
500.
500.
500.
500.
400.
400.
400.
400.
400.
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300.
300.
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300.
300.
300.
200.
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200.
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100.
100.
100.
100.
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300.
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800.
900.
600.
600.
500.
400.
300.
0.
0.
100. 200. 300. 400. 500. 600. 700. 800. 900.
0.
100. 200. 300. 400. 500. 600. 700. 800. 900.
600.
600.
500.
500.
500.
400.
400.
400.
400.
300.
300.
300.
300.
300.
200.
200.
200.
200.
200.
200.
100.
100.
100.
100.
100.
100.
Test
100.
0.
100.
600.
900.
Distance (cm)
0.
90
0.
0.
0.
100.
200.
300.
400.
500.
600.
700.
800.
0.
0.
900.
0.
100.
200.
300.
400.
500.
600.
700.
800.
0.
0.
900.
100. 200. 300. 400. 500. 600. 700. 800. 900.
max value
0.
Sinclair procedure on 900 samples
80
200.
300.
400.
500.
600.
700.
800.
900.
0.
600.
600.
500.
500.
400.
400.
300.
300.
200.
100.
100.
200.
300.
400.
500.
600.
700.
800.
900.
600.
"true" value
60
50
0.
30
20
10
0
0
50
100
150
200
250
300
350
400
450
500
550
number of samples
600
650
700
750
800
850
900
950
1000
100.
200.
300.
400.
500.
600.
700.
800.
900.
100.
200.
300.
400.
500.
600.
700.
800.
900.
600.
600.
500.
500.
500.
500.
400.
400.
400.
400.
300.
300.
300.
300.
200.
200.
200.
200.
200.
100.
100.
100.
100.
0.
0.
40
0.
600.
min value
70
mol/day
100.
0.
0.
0.
100.
200.
300.
400.
500.
600.
700.
800.
900.
100.
0.
0.
0.
100.
200.
300.
400.
500.
600.
700.
800.
900.
Starting from 900 sampling sites, the total emission estimation seems
to be reliable up to a total of 50 measurements points. The most
important effect is on flux maps that show drastic change from the
real situation
MASSA Spin-off – Riduzione dei rischi ambientali
How to get global gas emission
estimation from punctual
measurements ?
A critical revision of the data set is the first step of any kind of elaboration.
This preliminary analysis have to be focused to:
i. Evaluation of the influence of non detects values;
ii. Detection of outlier values
iii. Determination of the correct weight for the outlier values when there is a
clear origin (e.g. fractures)
The presence of outliers can be tested by means of both Box-Whisker plots
and other analytical process based on the Central Limit Theorem (Sigh A.,
1993; Sigh et al., 1997), depending on the statistical distribution of the data
set. Values lower than the instrumental detection limits are usually treated as
zero values.
MASSA Spin-off – Riduzione dei rischi ambientali
Isoflux maps
Isoflux maps are a fundamental tool to identify anomalous degassing areas
and to estimate the flux values where there are not measurements.
The question is: how to get reliable maps ?
There are a lot of deterministic interpolation methods:
i.Nearest neighbor method;
ii.Moving average within a neighborhood
iii.Inverse distances (IDW)
iv.Inverse of distances or squared distances
v.Spline
vi.………
MASSA Spin-off – Riduzione dei rischi ambientali
Isoflux map
293
294
292
27
28
60
61
94
296 291
26
29
59
62
93
290
25
24
23
1
2
3
4
22
21
20
19
30
31
32
33
34
35
36
58
57
56
55
54
53
52
63
64
65
66
67
68
69
92
91
90
89
88
95
96
97
98
87
86
167
163
168
162
169
203
103
118
200
38
50
71
84
105
115
7
16
39
49
72
83
106
8
15
40
9
14
10
13
41
46
75
80
109
112
12
42
45
76
79
110
111
11
43
114
20
77
78
108
179
264
10
274
259
271
258
267
257
268
270
253
288
145
278
282
279
281
286
269
254
277
285
146
144
276
283
280
287
289
256
255
0
50
185
184
147
143
275
100 m
Flusso mol/m 2* day
187
183
148
142
284
266
186
182
149
141
272
252
188
181
150
273
251
189
218
180
140
265
217
190
151
139
219
216
178
152
138
263
250
260
220
215
191
249
261
214
192
153
238
221
154
112.5 248
262
237
222
176
137
239
236
177
247
10
44
113
240
246
235
213
193
155
241
245
223
212
194
175
156
244
234
224
211
195
136
81
242
225
210
196
174
157
135
74
209
197
173
158
134
47
243
226
10
17
107
231
227
208
198
172
159
132
133
116
82
230
228
207
199
171
160
117
104
73
229
206
232
131
10
85
48
205
201
170
161
202
204
233
70
6
129
119
51
18
164
128
130
37
5
166
127
120
101
165
126
123
121
100
102
125
124
122
99
10
295
80.00
60.00
40.00
35.00
30.00
25.00
20.00
15.00
10.00
5.00
4.00
3.00
2.00
1.50
1.00
0.50
0.00
MASSA Spin-off – Riduzione dei rischi ambientali
Standard deviation map
MASSA Spin-off – Riduzione dei rischi ambientali
Isoflux maps: how to choose?

Deterministic approach
 The calculation of the
weights is only based on the
geometric location of the
measured data
 For a given data
configuration, whatever the
phenomenon looks like (from
regular to erratic), we get the
same prediction map
Inverse distances
Inverse of squared distances
 Making a choice needs to
add subjective criteria as,
« does the map look realistic
or not ? »
MASSA Spin-off – Riduzione dei rischi ambientali
Isoflux maps: geostatistics methods
Geostatistics is based on the definition of a regionalized variable, a variable with
geographic data location, continuous in the space, with deterministic and random
correlation in each point. To investigate these correlations mean to understand the spatial
structure of the observed phenomenon. The tool used to get information about spatial
correlation and structure is the (semi)variogram.
Interpolation data processing with geostatistics methods mean to follow 5 main steps:
• Data analysis and computation of variogram and variogram cloud;
• Selecting of the right mathematical model to fit the experimental variogram;
• Choosing of the proper neighborhood
• Cross validation
• Kriging
Kriging method (Krige 1951; Matheron, 1962; 1965; 1969; 1970; Clark, 1979; David,
1977; Davis, 1986) allow to extrapolate values where the measures had not been taken.
MASSA Spin-off – Riduzione dei rischi ambientali
Kriging e costruzione del semivariogramma
Data base map
Variogram model
Variogram cloud
Experimental Variogram
MASSA Spin-off – Riduzione dei rischi ambientali
Come si fa la valutazione globale dei flussi di gas
• The total flux can be determined with the
integral
Q   F ( x, y)dxdy
A
Specific Flux
MASSA Spin-off – Riduzione dei rischi ambientali
Isotopic gas monitoring
Two reasons
Source identification
Identification of biological processes
MASSA Spin-off – Riduzione dei rischi ambientali
AIR POLLUTION MODELING : CALPUFF
Area: 10Kmx10Km
Grid: 250 m
Nx=40 Ny=40
Data input
Diffuse pollution from landfill
Landfill surface 83 000 m2
Modeled compound: CH4
MASSA Spin-off – Riduzione dei rischi ambientali
hourly
concentrations
MASSA Spin-off – Riduzione dei rischi ambientali
Thank you for your attention…
OBRIGADO!