MASSA Spin-off – Riduzione dei rischi ambientali

MASSA Spin-off – Riduzione dei rischi ambientali


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.

Universidade de FlorençaUniversidade de Florença


Conselho Nacional de Pesquisas Conselho Nacional de Pesquisas CNRCNR

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


M.A.S.S.A. Spin-offM.A.S.S.A. Spin-offMetodologias e Aplicações Científicas para a Metodologias e Aplicações Científicas para a

Salvaguarda AmbientalSalvaguarda Ambiental Oferecer soluçoes para mitigaçao dos impactos ambientais.

MONITORAMENTO DE RISCOS


European directiveEuropean directiveMember 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.


Waste hierarchyWaste hierarchy


LandfillsLandfills

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

Stringent operational and technical requirements on the waste and landfills


Municipal waste productionMunicipal waste production


Municipal waste recycledMunicipal waste recycled


Municipal waste incineratedMunicipal waste incinerated


Landfills are still presentLandfills are still present


Municipal waste landfilledMunicipal waste landfilled


Even if people don’t like them…Even if people don’t like them…


……Sanitary landfills are much better then uncontrolled Sanitary landfills are much better then uncontrolled disposaldisposal


CONTROL AND MONITORING PROCEDURES IN CONTROL AND MONITORING PROCEDURES IN OPERATION AND AFTER-CARE PHASESOPERATION 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.


How is a landfill made…How is a landfill made…


Technical features3 type of landfills

(a) excavated trench (b) area (c) canyon/depression

(b) (c)


Municipal waste degradation produce leachate and biogas, main landifill vectors of environmental pollution. 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.

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).

Biogas

Gas produced by the biological breakdown of organic matter. Biogas comprises primarily methane (CH4) and carbon dioxide (CO2).

Chemical, Physical and Biological processes Chemical, Physical and Biological processes inside municipal landfillinside municipal landfill


Existing site drainage must be modified to route any runoff away from the area. Existing site drainage must be modified to route any runoff away from the area.

Preparation of the site for landfillingPreparation of the site for landfilling

Excavation and preparation of the landfill bottom and subsurface sides. Geomembrane liners are installed.Excavation and preparation of the landfill bottom and subsurface sides. Geomembrane liners are installed.


Leacheate collection and extraction facilities are placed within or on the top of the liner.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.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

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





Phase I. Initial adjustment phase 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.


Phase II – Transition phase 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.


Phase III: Acid phase 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.


Phase IV: methane fermentation phase 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.


Phase V: Maturation phase 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.



Quality and quantity of biogas and leachate result from numerous elements

Environmental characteristics

RainfallAir temperatureAir UmidityWind

Environmental characteristics

RainfallAir temperatureAir UmidityWind

Waste characteristics

DensityPre-treatmentsWaste UmidityWaste product analysisWaste granulometry

Waste characteristics

DensityPre-treatmentsWaste UmidityWaste product analysisWaste granulometry

Landfill

Type and geometryCoverage materialsBiogas and leachate drainage techniques

Landfill

Type and geometryCoverage materialsBiogas and leachate drainage techniques


Typical constituents found in MSW Typical constituents found in MSW landfill gas 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


Typical data (mg/l) on the composition of leachate 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

Alkalinity as CaCO3 3.000 600

pH 6 7

Chloride 500 250

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


Biogas and Leachate controlBiogas 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.

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.


Leachate monitoringLeachate monitoring


Chemical parameters to be controlled 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.

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.

Often what Regulations ask is not sufficient to identify a possible dangerous mixing between natural water and leachate.


Isotopes 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.

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.


Leachate isotopic monitoring 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.

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.

In a landfill monitoring system, isotopes can be used a tracer of water pollution due to leachate mixing.


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).

18O/16O

2H/1H

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).

3H/H

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)

Principal isotopic parameters Principal isotopic parameters


Craig, 1961 – con modifiche

WORLD RAINFALL LINEAR REGRESSION


2H and 18O

COMPARISON BETWEEN

RAINFALL WATER AND

LEACHATE

LEACHATES COMING FROM ANAEROBIC DEGRADATED ORGANIC WASTE

WORLD RAINFALL LINE

WORLD RAINFALL LINE

MEDITERRANEAN RAINFALL LINE

MEDITERRANEAN RAINFALL LINE


1

10

100

1000

1950 1960 1970 1980 1990 2000 Anno

U.T

.

U.T. Piogge Genova proiettate al 2006

U.T. Piogge Pisa proiettate al 2006

ESPLOSI ONI TERMONUCLEARI I N ATMOSFERA

Concentration of TRITIUM (3H) in Italian rainfall water


1

10

100

1000

1950 1960 1970 1980 1990 2000 Anno

U.T

.



ESPLOSI ONI TERMONUCLEARI I N ATMOSFERA LANDFILL LEACHATE 3H

CONCENTRATION FREQUENTLY

RANGES FROM 200 AND 1500 U.T.

SOMETIMES IT CAN ACHIEVE MORE

THAN 3000 U.T.



1

10

100

1000

1950 1960 1970 1980 1990 2000 Anno

U.T

.



ESPLOSI ONI TERMONUCLEARI I N ATMOSFERA

THIS CLEAR DIFFERENCE ALLOW TO FIND OUT LOW WATER

CONTAMINATION FROM LEACHATE

(EVEN LESS (EVEN LESS 1% OF LEACHATE)1% OF LEACHATE)

LANDFILL LEACHATE 3H

CONCENTRATION FREQUENTLY RANGE

FROM 200 AND 1500 U.T. SOMETIMES IT

CAN ACHIEVE MORE THAN 3000 U.T.



TRITIUM versus CHLORIDES

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triz

io (U

.T.)

cloruri (mg/l)

TRIZIO VS. CLORURI

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trizi

o (U

.T.)

cloruri (mg/l)

TRIZIO VS CLORURI

percolato

punti d'acqua

Curve che delimitano il campo di potenziale mescolamento

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io (U

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TRIZIO VS CLORURI

percolato

punti d'acqua


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io (U

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TRIZIO VS CLORURI

percolato

punti d'acqua


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io (U

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TRIZIO VS CLORURI

percolato

punti d'acqua


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io (

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.)

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TRIZIO VS. CLORURI

LEACHATE GROUNWATER SAMPLE

POTENTIAL MIXING CURVES


13C‰ 13C‰

LEACHATE

Range from +15 and +30

LEACHATE

Range from +15 and +30

GROUNDWATER

Range from - 25 and 0

GROUNDWATER

Range from - 25 and 0

CARBON ISOTOPE


OTHER ISOTOPES PARAMETERS

34S‰

of dissolved

sulphate

LEACHATE

Frequently around +8

GROUNDWATER

Range from - 21 and - 8

18O‰

of dissolved

sulphateLEACHATE

Frequently around +27

GROUNDWATER

Range from - 0,20 and +11,40


Biogas monitoringBiogas monitoring


It is really important to identify and quantify the biogas sources inside a landfill:

• Diffuse sources from the coverage

• Gas extraction wells

• Biogas flares

• Biofilters

Air pollution control

A relevant part of the biogas could be diffused into the atmosphere.A relevant part of the biogas could be diffused into the atmosphere.


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.

Monitoring biogas diffusion from coverage


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.

Physical laws: diffusion and advectionPhysical laws: diffusion and advection


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.

How to estimate the total emissionHow to estimate the total emission


There are various different systems to get soil gas flux measurements. The principal developed techniques can be divided in three main categories:

i.Measurements of the gas concentration gradientii.Micro-meteorological techniques (e.g. eddy correlation)iii.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.

Measurement techniquesMeasurement techniques


The accumulation chamber methodThe accumulation chamber methodThe 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


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.

Accumulation chamber: calibrationAccumulation chamber: calibration


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.

Accumulation chamber: field Accumulation chamber: field measurementsmeasurements


The right sampling gridThe right sampling gridTo 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)


The sampling gridThe sampling grid

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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.

The right sampling gridThe right sampling grid

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8 00 .

9 00 .

9 00 .

0 . 0 .

1 00 . 1 00 .

2 00 . 2 00 .

3 00 . 3 00 .

4 00 . 4 00 .

5 00 . 5 00 .

6 00 . 6 00 .

0 .

0 .

1 0 0 .

1 0 0 .

2 0 0 .

2 0 0 .

3 0 0 .

3 0 0 .

4 0 0 .

4 0 0 .

5 0 0 .

5 0 0 .

6 0 0 .

6 0 0 .

7 0 0 .

7 0 0 .

8 0 0 .

8 0 0 .

9 0 0 .

9 0 0 .

0 . 0 .

1 0 0 . 1 0 0 .

2 0 0 . 2 0 0 .

3 0 0 . 3 0 0 .

4 0 0 . 4 0 0 .

5 0 0 . 5 0 0 .

6 0 0 . 6 0 0 .

Grid dimension=chamber diameter Extraction

0

10

20

30

40

50

60

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90

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000

number of samples

mo

l/da

y

"true" value

Sinclair procedure on 900 samples

min value

max value

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


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 valuesiii. 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.

How to get global gas emission How to get global gas emission estimation from punctual estimation from punctual

measurements ? measurements ?


Isoflux mapsIsoflux 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.………


Isoflux map

10

10

10

10

10

20

80.0060.0040.0035.0030.0025.0020.0015.0010.00 5.00 4.00 3.00 2.00 1.50 1.00 0.50 0.00

Flusso m o l/m * d a y2

7 9

8 0

8 1

8 2

8 3

8 4

8 5

8 6

8 7

8 8

8 9

9 0

9 1

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9 3

9 4 9 5

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1 0 0

1 0 1

1 0 2

1 0 3

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1 0 5

1 0 6

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1 1 0 1 1 1

1 1 2

1 1 2 .5

1 1 3

1 1 4

1 1 5

1 1 6

1 1 7

1 1 8

1 1 9

1 2 0

1 2 1

1 2 2

1 2 3

1 2 41 2 5

1 2 6

1 2 7

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1 3 0

1 3 1

1 3 2

1 3 3

1 3 4

1 3 5

1 3 6

1 3 7

1 3 8

1 3 9

1 4 0

1 4 1

1 4 21 4 3

1 4 4

1 4 5

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1 5 0

1 5 1

1 5 2

1 5 3

1 5 4

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1 6 0

1 6 1

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1 8 0

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1 8 51 8 6

1 8 71 8 81 8 9

1 9 0

1 9 1

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1 9 3

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1 9 9

2 0 0

2 0 1

2 0 2

2 0 3

2 0 4 2 0 5

2 0 6

2 0 7

2 0 8

2 0 9

2 1 0

2 1 1

2 1 2

2 1 3

2 1 4

2 1 5

2 1 6 2 1 72 1 8

2 1 92 2 0

2 2 1

2 2 2

2 2 3

2 2 4

2 2 5

2 2 6

2 2 7

2 2 8

2 2 9

2 3 0

2 3 1

2 3 2

2 3 3

2 3 4

2 3 5

2 3 6

2 3 7 2 3 8

2 3 9

2 4 0

2 4 1

2 4 2

2 4 3

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2 5 0

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2 4 7

2 4 8

2 5 1

2 5 2

2 5 3

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2 5 6

2 6 0

2 6 1

2 6 22 6 3

2 6 4

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2 7 0

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2 9 3 2 9 4

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2 9 6

1

0 50 100 m

2

3

4

5

6

7

8

9

1 0

1 1

1 2

1 3

1 4

1 5

1 6

1 7

1 8

1 9

2 0

2 1

2 2

2 3

2 4

2 5

2 6

2 7 2 8

2 9

3 0

3 1

3 2

3 3

3 4

3 5

3 6

3 7

3 8

3 9

4 0

4 1

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4 3 4 4

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7 7 7 8


Standard deviation map


Isoflux maps: how to choose?Isoflux maps: how to choose?

340 350 360 370 380 390 400 410 420 430 440

X (km)

5275

5300

5325

5350

5375

5400

5425

Y (km)

NO2

50

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5

0

Inverse distances

340 350 360 370 380 390 400 410 420 430 440

X (km)

5275

5300

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5375

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5425

Y (km)

NO2

50

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5

0

Inverse of squared distances

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

Making a choice needs to add subjective criteria as, « does the map look realistic or not ? »


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.

Isoflux maps: geostatistics methodsIsoflux maps: geostatistics methods


Variogram cloudData base map Experimental Variogram

Kriging e costruzione del semivariogramma Kriging e costruzione del semivariogramma

Variogram model


Come si fa la valutazione globale dei flussi di gas

• The total flux can be determined with the integral

( , )A

Q F x y dxdy

Specific Flux


Isotopic gas monitoringIsotopic gas monitoring

Two reasons

Identification of biological processesIdentification of biological processesSource identificationSource identification

1E-006 1E-005 0.0001 0.001 0.01

1/CO2 (ppm-1)

-45

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-5

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13C

CO

2 (‰

)

1E-006 1E-005 0.0001 0.001 0.01

-45

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-5

0

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Riscaldamento

Veicoli

Biogas Toscana

Emissioni naturali

Biogas Emilia

Aria area urbana

Aria Campus Jussieu

Aria area suburbana

Respiration Coal

Diesel

Combusted Natural gas

Leaded

Unleaded

Domestic fuel oil

UnpolluttedAir end-member

Classroom air

Parking lot


Area: 10Kmx10Km

Grid: 250 m

Nx=40 Ny=40

Data input

Diffuse pollution from landfill

Landfill surface 83 000 m2

Modeled compound: CH4

AIR POLLUTION MODELING : CALPUFF


hourly concentrations


Thank you for your attention…Thank you for your attention…

OBRIGADO!OBRIGADO!

Documents

MASSA Spin-off – Riduzione dei rischi ambientali