Air, Water and Land Pollution Chapter 5: Investigating the Environment Copyright © 2009 by DBS.

Air, Water and Land Pollution

Chapter 5:Investigating the Environment

Copyright © 2009 by DBS

Contents

• Monitoring

• Types of monitoring

• Sampling methods

• Modeling of environmental dispersion

• Duration and extent of survey

• Prerequisites for monitoring

• Remote sensing

Monitoring:A Systematic Investigation of the Environment

• Existence and concentration of substances in the environment is found via measurement

• Single measurements not very useful…why?

• Environment is variable (sampling strategy needs to account for this)

• Require knowledge of temporal and spatial variations

e.g. NO3- in river water

Different results would be found a few km downstream due to physical, chemical and biological transformations

Reeve, R.N. (2002)


• Specific investigation of the environment requires:

– monitoring by repeated measurements made over time and space

– sufficient sample density to make a realistic assessment of variations and trends


• Important to define the reasons for monitoring before starting any investigation

Generalization:

Monitoring is done in order to gain information about the present levels of harmful or potentially harmful pollutants in discharges to the environment itself, or in living creatures that may be affected by these pollutants


• Specifics - Monitoring may be carried out to:

(a) assess pollution affects on man and his environment, and to identify any possible cause and effect relationships between pollutant concentrations and, for example, health effects, or environmental change

(b) assess the need for legislative controls on emissions and to ensure compliance with standards

(c) activate emergency procedures in areas prone to pollution episodes

(d) obtain a historical record of environmental quality (useful, for example in epidemiological studies)

(e) to ensure the suitability of water supplies or land for domestic or industrial use


Designing a Monitoring Program

• Number and location of sampling sites, measured parameters, duration of the survey, time resolution of sampling all vary according to what the collected data are to be used for

• Starting with a clearly defined purpose and objectives is key

• Continual appraisal of the data generated can be used to adjust the organization or execution of the survey if necessary


• Systematic steps in a monitoring program

Types of Monitoring

May have any combination of:

Phases of pollutants

• Solid

• Liquid

• Gas

In compartments:

• Atmosphere

• Hydrosphere

• Biosphere

• Lithosphere

Types of Monitoring

• Specific phase in a particular compartment

e.g. sulfur dioxide in air

• Two or more phases in a particular compartment

e.g. dissolved and particulate phase metals in water

Types of Monitoring

• Two distinct approaches to monitoring:

Source monitoring – samples taken before discharge and dispersion to the environment (point source)

Ambient monitoring – samples taken after discharge from multiple sources (non-point sources)

Types of MonitoringSource Monitoring

General Objectives

• Source monitoring may be carried out to:

– Determine emission rates, and assess how these are affected by process variations

– Evaluate pollution control devices

– Evaluate emission compliance


Stationary Source Sampling (Gases)

• Industrial processes are cyclical

• Must be representative of the entire plant

• EPA has standard test methods for emissions monitoring


Mobile Source Sampling (Gases)

• Vehicle emissions are heavily dependent on operating conditions

• May be done when idling or under specific conditionse.g. using a dynamometer of ‘rolling road’


Source Monitoring (Liquids)

• Liquid wastes (effluents)tend to be heterogeneous

• Care is required when selecting sampling locations, region should be well mixed

• If homogeneous regions are not available, samples may need to be taken at several locations

• If composition varies with time, grab samples will need to be taken and integrated over the time span


Source Monitoring (Solids)• From wastewater/sewage treatment (sludge), ash from incinerators, gypsum from

desulfurization plants in power stations• Less homogeneous than liquid or gas effluents• Must ensure sample is representative of the whole waste

• e.g. EPA sets sewage sludge application levels for heavy metals– Sludge is regularly monitored for heavy metals– 80-100% of Pb in a sewage treatment plant ends up in sludge– Pb levels 100-3000 μg/g (ppm)– Used in many countries as a fertilizer


Source Monitoring (Solids)

• Pollution loading: Analysis of samples gives total elemental concentration

• Total metal concentration is not very useful

• Physical, chemical and biological responses to pollution varies according to its speciation:

– Determines behavior under varying conditions of pH and pe

– Determines solubility

– Determines association with particles and organic matter

• Information on physiochemical speciation is required

• Complicated and time consuming compared with total metal determination

Speciation

Mercury Ion Hg2+

AKA ‘reactive gaseous’ mercury’ (RGM) e.g. HgCl2(g)

Methyl MercuryCH3Hg+

Elemental MercuryHg0

Particulate bound Hg-P

Inorganic Organic

ReactiveVolatile

Global Regional ?

Dimethyl MercuryCH3HgCH3


Source Monitoring (Solids)

• e.g. mercury case study – previously assumed only inorganic Hg (metallic mercury) released in landfill gas


Atmospheric Environment, Vol. 39, pp. 249-258.

Types of MonitoringAmbient Monitoring

General Objectives• Samples should be representative of prevailing conditions at the time and place of

collection• Careful choice of sampling location and position at the chosen location• Selection of site requires consideration of 4 steps:

– Identification of the purpose of monitoring– Identification of the type of site that will best serve this purpose– Identification of the general location of sites– Identification of specific monitoring sites


Ambient Air Monitoring

(a) Source-orientated sites for monitoring individual or small groups of emitters

(b) Large-scale surveys of expected high pollutant concentrations

(c) Baseline stations to obtain background concentrations, usually remote or rural sites


Ambient Air Monitoring• (a) Source Oriented

– Sited at point of anticipated maximum ground level concentration and at a background location

– e.g. using Gaussian dispersion models



• (b) Large-scale Surveys

– Geographical extent of air pollution

– Can provide real-time data to public

– Historical archived information

– e.g. Local (Health Dept.) and regional (EPA) monitoring networks

http://www.pittsburghtoday.org/web/chart.jsp?id=5_3_2&type=graph&gr=mcya_cr_n

http://www.epa.gov/air/data/repsst.html?st~PA~Pennsylvania


Ambient Air Monitoring• (c) Baseline stations to obtain background concentrations, usually remote or

rural sites Geographical extent of air pollution– Principal siting requirement is that background levels need to be

measured over a long time period without interference from local sources

e.g. 1) long-term measurement of CO2 at Manua Loa since 1956, and

e.g. 2.) national radon studies

Tellus, Vol. 28, No. 6, pp. 538-551.

Health EffectsRadon Gas

Progenies (‘daughters’) build up in confined space –are breathed in, stick to surface of airways and emit α-particles

Source: Turco (2002)



• e.g. Radon surveys


Environmental Water Monitoring

• Enter from air (dry or wet deposition), land (runoff), direct discharge (domestic, agricultural, industrial)

• Undesirable effects:

– Stimulation of plant growth – eutrophication – deoxygenation and loss of biodiversity

– Direct or indirect toxic effects on biota

– Loss of amenity and practical value of water body



• Sampling may be carried out:

(a) in rivers, lakes estuaries and the sea – overall water quality

(b) for rainwater, ground water and runoff – to assess influence of pollutant sources

(c) at points where water is taken for domestic supplies

(d) using sediments and biota in order to assess accumulation of pollutants and as indicators of pollution



• Biomonitors or ‘biomarkers’ are organisms collected from contaminated sites, or placed at a contaminated site for a period of time after the event has occurred

• Analyzed in the lab chemically for toxins

e.g. collection of mussels and subsequent analysis for heavy metals


Environmental Water Monitoring• Location of Sampling Sites

– Sampling should be done at points representative of he bulk of the water body

– Studies of some pollutants require sampling at considerable distances downstream of effluent inputse.g. Dissolved oxygen

– Variable discharges with time requireclose proximity to point of input


Environmental Water Monitoring• Location of Sampling Sites

– Temporally variable discharges require sampling in close proximity to point of input

– Dilution

– Contaminant levels no longer show variation with time



• Sampling in Lakes

– e.g. enrichment or eutrophication of lakes - excessive ‘blooms’ of cyanobacteria (blue-green algae)


Once this increased biomass dies and settles to the bottom of the water body where decomposition occurs, oxygen levels may become depleted thus killing off fish and other animals, releasing phosphorus from the sediments (i.e. internal loading), and a suite of other problems.


Killed 16 cows on a farm near Baldur, Manitoba (Canada) in 1996.

Certain cyanobacteria can produce nerve toxins that render water unsafe (Carmichael, 1994; 1997)

Hydrobiologia, Vol. 495, pp. 79-91.



• Sampling of Natural Waters

– e.g. Arsenic

Source: http://water.usgs.gov/nawqa/trace/arsenic


Sediments and Soil Monitoring• May become polluted in a number of ways:

(a) Substances may get into soil/plants and then into the food supply

(b) Substances may wash from the land and pollute water supplies

(c) Contaminants may be resuspended and subsequently inhaled

(d) Substances polluting the land may make it unsuitable for future use

(e) Ecological systems may be damaged


Sediments and Soil Monitoring

• Many contaminants are also naturally occurring (background levels)

• Some contaminants are solely anthropogenic (e.g. pesticides and artificial radionuclides)

• Many studies on heavy metal contamination have established sources and relative contributions to total intake of humans

e.g. Pre-Incan Metallurgy and the New World

Metals and the EnvironmentIntensive Pre-Incan Metallurgy and the New World

• 15-16th century well known use of Ag by Incans• “mountain of silver” in Bolivian Andes

– AD 1130-1150 peak in Pb and others(used in smelting silver)

– Coincides with Tiwanaku Empire and decline due to drought

– Ag exhausted in 16th century, start of Sn mining in 19th century

Shaded zones identify distinct metallurgical zones:

-Tiwanaku (AD 1000 to 1250), - Inca - early Colonial (AD 1400 to 1650), - rise and crash of tin mining (AD 1850 – 1950)

(Abbott and Wolfe, 2003)



• e.g. application of sewage sludge to land

– Samples of surface water, groundwater, soil, vegetation and sludge would be tested for fecal coliform, nutrients, metals and pH

– Results would be compared to predicted levels



• Background levels may be derived from measurements in plants or organisms that soils and sediments support

e.g. lichens and shellfish act as bioconcentrators of heavy metals



• e.g. Dioxins and furans in soils around an incinerator

– Incinerators are a major source of chlorine containing toxic organics

– Columbus incinerator estimated to have produced nearly 1 kg/yr of dioxin TEQ

– 1/10th of total US output

– Unit was closed due to this massive output

– Since no air data was available, had to study soil



• e.g. Dioxins in soils around an incinerator

– Soil showed characteristic ‘fingerprint’ of toxic organics released

– Clear decrease in concentration with distance from source

– 15,747 pg/g total dioxin on-site, 235 pg/g for background samples

Lord

er e

t al

., 1

998


Biological Monitoring

• Well-recognized relationships exist between the abundance and diversity of a species and the degree of pollution

e.g. frogs and fish are frequently used in water treatment facilities

• Number and types of species or taxonomic families at a particular location and comparing this data to a reference background one

• Macroinvertebrates (e.g. insects, mollusks, nematotodes etc.) are often used in assessing the biological quality of rivers

Sampling Methods

Sampling Methods

• Monitoring of pollutants involves:

(i) collection of air, water, and soil/sediment samples for laboratory analysis

(ii) instantaneous instrumental monitoring of air and water

• In this section we will look at sample collection methods.

Sampling MethodsAir

Air Sampling Methods

• Sampling systems for airborne pollutants may be active or passive

• Usually consist of 4 component parts:

– Intake component

– Collection (or sensing) component

– Flow measuring component

– Air moving device (pump)

• Note: All must be chemically and physically inert to the sampled air (other than the collector or sensor itself)

Sampling MethodsAir


• Intake Design

– Dependent on analyte

– e.g. vertical opening for dustfall deposit gauge

Dustfall gauge:- Deposits via gravitational settling- Used to calculate depositional flux (mg m-2 d-1)- Bulk sampling device

Horizontal dust deposit gauge (Deposition)

Directional dust gauge (flux)

Sampling MethodsAir


• Intake Design

– Sampling aerosols is particularly difficult, inlet is usually a tube

– Flow rate of sample at the inlet should be equal to the flow of the gas being sampled [case (b)]

Too few particles

Too many particles

Disturbance at the intake can lead to under or over sampling…

Sampling MethodsAir

Air Sampling Methods• Sample Collection

Methods most commonly used for atmospheric particulate samples:– Filtration;– Impingement;– Sedimentation;

And for gaseous samples:– Adsorption;– Absorption;– Condensation;– Grab samples

Sampling MethodsAir


• Sample Collection

– Filtration

Chose correct filter for analyses:Retain correct sizeAbsence of impuritiesCompatible with analytical procedure

Pros Cons Use

Glass FIber

- Low water uptake

- High efficiency for particles > 0.3 μm

- Resistant to high T

Organics

Cellulose

- Low head loss

- Low metallic contamination level

- Easily ashed

- HydrophillicMetals + inorganic ions

Membrane

- Flat for microscopic analysis

- Hydrophobic

- Chemically resistant

- Large head loss

- Brittle

- Not resistant high T

Sampling MethodsAir

Air Sampling Methods• Sample Collection

– Impingement – cascade impactors

(i) small jets through which an air stream is forced, velocity and momentum of suspended particles is increased

(ii) particles collect on impaction surfaces

- Uses adhesion of PM rather than filtration- Flow is constricted, velocity increases- Successively smaller particles adhere to each successive surface- Fractionated according to mass (2.5 – 10 μm / < 2.5 μm)

Sampling MethodsAir



– Sedimentation

e.g. frisbee-type deposit gauge –during wet weather dust is washed into collection bottle

Sampling MethodsAir



– Adsorption – gas molecules bound by intermolecular attraction to a surface

– Used for low-concentration VOC’s

e.g. activated charcoal, silica gel, alumina, polymers (Tenax Resin, PUF)

Sampling MethodsAir



– Absorption – gases may be collected by dissolving in liquid phase or by chemical reaction

e.g. NO2 via Palmes diffusion tubes

Sampling MethodsAir



– Grab sampling – gas samples collected in an impermeable container and analyzed in the lab

e.g. determination of organics via GC-MS

– collection in Teflon bag or SS canister

Sampling MethodsAir

‘Hi-Vol’ sampler

• Determines total suspended particulates (TSP) mg/m3

• Pump up to 90 cfm (~150 m3 h-1)

• Draws large volume of air over 24 hr period

– Glass fiber or membrane filter

– Weighed before and after

– 0.3 to ~100 μm particle size

• Impaction inlet may be used for PM-10, PM-2.5

• May analyze filter for chemicals

Reeve, 2002

Question

Calculate the PM-10 concentration for the following conditions:

Filter mass gain = 0.000670 mg

Sample time = 1446 min

Initial sampler flow rate = 1.875 cm3 min-1

Final sampler flow rate = 1.807 cm3 min-1

Average flow rate = 1.841 cm/min

Volume of air = 1.841 cm3/min x 1446 min = 2662 cm3 = 2.662 x10-3 m3

PM concentration = 6.70 x 10-1 μg / 2.662 x 10-3 m3 = 251.7 μg m-3

Sampling MethodsWater

• 500 mL to 2.0 L typical volume

Objective:

Collect a portion of material small enough in volume to be transported and large enough for analysis while still accurately representing the material being sampled


Grab - bottle, bag, messenger (Niskin, Kemmerer or Van Dorn type), peristaltic pump Depth Integrating – vertical water column

Automatic – remove samples at fixed intervals


• Adsorption of filtration media may be used to concentrate the species of interest in situ

e.g. trace metals, organics, radionuclides

• Peristaltic pumps have been used to sample water at various depths in lakes


Container and Preservation Choices

• Plastic is typically used

• Glass – hard glass (Pyrex) recommended for all organics

• Amber Glass – recommended for light-sensitive compounds

• 1 L sample necessary for most analyses

• Some determinations require preservation prior to analysis

See p1-33 of Standard Methods Book

1-33

Standard Methods (1998)


Contamination issues

• Care must be taken to ensure that sample container and collecting equipment do not contaminate the samples

• Occurs via:

– Leaching of contaminants from surface of containers

– Leaching of organic substances from plastics or glass

– Adsorption of trace metals onto surfaces of containers

– Reaction of the sample with container material

– Change in equilibrium between pollutants in particulate and solution phases

• If sample is to be subjected to an extraction technique then extraction reagents must be sufficiently clean

Sampling MethodsSoil and Sediments

• Typically inhomogenous – large variations• Surface samples are possible – truer representation obtained with cores• Usually plastic core tubes – extruded in field or lab


• Stored in plastic bags

• Usually soils and sediments are air dried, disaggregated (mortar and pestle), sub-sampled and stored prior to analysis

• Important to avoid contamination at each step

Sampling MethodsSediments

Coring platform

• Cores are taken through the water column

• From a boat, platform or ice cover

• Coring equipment

Collecting surface lake sediments using a small diameter Glew (1991) gravity corer from the pontoons of a helicopter in Arctic Canada.

Smol, 2008


Coring equipment• Last 100 years contained in 50 cm (N. America) (cf. fast accumulation)• More ancient histories contained in cores 2 m or longer• Recent sediments are ‘unconsolidated’ > 90 % water

Short Cores (Surface Sediments)• Open-barrel gravity corers

(plastic tubes)– Close-on-contact type

(line tension)– Messenger-operated


Surface sediments

• Freeze-crust samplers

• Designed to preserve chemistry of the sediment-water interface

Figure 4.3. General operation of a freeze-crust sampler.

Inset: Corer chamber is filled with dry ice and a coolant, such as alcohol. The corer top is secured.

A: Corer is lowered through the water column

B: Corer is lowered into the sediment, sediment freezes to the corer C: Sediment-encrusted corer brought to the surface.


Long Cores

• Livingstone corer

– Rod driven piston corer

Simplified diagram showing the basic principles used in piston coring.

A) To recover an undisturbed core sample, the corer is positioned at the sediment surfaceB) The piston held stationary, while the core tube is pushed past it into the sediment using the coring rod. C) The core section is recovered to the surface, with the core tube and piston locked together. The sealing of the piston in the core tube prevents any tendency for the sample to slide out or for the core material to be deformed.


Long Cores

• Mackereth compressed air piston corer (Mackereth, 1958; 1969)


Sediment Sectioning

• Should be sectioned lake-side / ASAP

Modeling of Environmental Dispersion

• Substances can be found over large ranges of concentrations

• Analytical techniques must be very flexible

Ions Found in Natural Waters

Conc. Range

(mg L-1)

Cations Anions

0-100 Ca2+, Na+ Cl-, SO42

-, HCO3-

0-25 Mg2+, K+ NO3-

0-1 Fe2+, Mn2+, Zn2+ PO43-

0-0.1 Other metal ions NO2-

Reeve, 2002

Ariola et al, 2004


• In order to appreciate the variability of pollutant levels, and hence the complexity of designing an adequate monitoring porogram it is necessary:

(i) to have some understanding of environmental dispersal, mixing and sink processes

(ii) to have some understandingd of the time scales over which these processes act

• Modeling of dispersal is complex, uses computer models

Modeling of Environmental DispersionAtmospheric Dispersal

• Advection (wind) and turbulent diffusion (mixing) are the primary dispersion routes

• Vertically limited to the boundary layer (layer closest to earth’s surface)

• Important factors:

– Wind direction and speed

– Solar radiation, cloud cover

– Release height of plume and buoyancy

– Topography

– Surface obstructions, buildings etc.

– Loss mechanisms (deposition at ground, chemical reactions)

Modeling of Environmental DispersionAtmospheric Dispersal

• Simplest model is Guassian plume model (chp. 2)

– Good short-term estimates (within factor of 3), longer-term estimates require newer models (AERMOD, ADMS)

• Modeling produces good estimates of the real situation

– Must understand limitations of the model

– Avoid treating output as definite answers

– We may have good wind speed data but turbulence characteristics poorly understood

Modeling of Environmental DispersionAquatic Mixing

• Advection (movement of water) and mixing/diffusion are the primary dispersion routes (same as air!)

• Vertical mixing is constrained by water depth or thermal stratification

• Large number of models to describe movement of water pollutants

e.g. river model – estimate of long-term average concentrations at point of discharge from a continuous release:

C = q

v(1 + KdS)

Where q = rate of input of a substance to the river (kg s-1), v = flow rate (m3 s-1), Kd = partition coefficient (m3 kg-1) and S = suspended solid load (kg m-3)

Modeling of Environmental DispersionAquatic Mixing

• e.g. exponential decay model to predict (i) the change in water quality downstream from a discharge into a river,

Cx = C0e-kt

Where Cx = concentration at point x, Co = initial concentration at point of discharge, k = decay constant, t = time taken for flow from point of discahrge to x

• or (ii) decline in organic pollution levels in a lake

Ct = C0e-kt

Where Ct = concentration at time t, Co = initial concentration, k = decay constant, t = time

• More recent models account for sorption, volatilization, hydrolysis, photolysis, oxidation, etc. (see for example MINEQL, FATE etc.)

Question

The PCB concentration in Lake Michigan is declining according to a first-order rate constant of 0.078 yr-1. If the PCB concentration averaged 0.047 ppt in 1994, what will it be in 2010? In what year will the concentration fall to 0.010 ppt? What is t1/2?

Find t when C = 0.010 ppt

0.010/0.047 = e-0.078t

t = 19.8, concentration declines to 0.010 ppt by the year 2014

t1/2 = ln2 / k = 8.9 y

C = C0e-kt

Let 1994 be equivalent to t = 0

2010 will be t = 16 y

C = 0.047e-0.078 x 16 = 0.047e-1.248 = 0.013 ppt

Modeling of Environmental DispersionVariability in Soil and Sediment Pollutant Levels

• Physical mixing by agricultural practices, dredging, bioturbation by burrowing organisms

• Level of contamination depends mainly on deposition rate and vertical/horizontal migration

• Rate of movement is dictated by the degree of adsorption, leaching from particles and flux rate of pore waters

• Physiochemical properties influence rate of adsorption or leaching

e.g. Pb favored by low rainfall and high clay content, Hg favored by high SOM

Modeling of Environmental DispersionVariability in Soil and Sediment Pollutant Levels

• Contaminant concentrations are usually higher in soils or sediments with finer grain size (increased surface area for adsorption)

Trace metal concentrations in sewage sludge

Cu associated with SOM

Zn associated with small particles and SOM

Duration and ExtentDuration of Survey and Frequency of Sampling

• Dependent on purpose of study

• Pollutant levels fluctuate – long-term mean data not as useful as short-term (may miss pollutant maximums)

• More variability requires more samples to assess trends

• Fast response continuous monitors can be used for the more common air pollutants and basic water parameters

• Require calibration and periodic checks


• D

Carnegie Sci. Center EPA Monitor


• Methods for water analysis:

Duration and ExtentMethods of Reducing Sampling Frequency

• Sampling frequency may be impractical with resources on hand

• Can be reduced by:

– Reducing the number of sampling locations

– Reducing the sampling frequency

– Reducing the number of determinants

• Also possible to use composite samples to reduce sample numbers

• Mix two individual samples to give indication of average quality over a given area

Duration and ExtentNumber of Sites

• Dependent on objectives of the study

• Proability of a fixed number of stations dtecting a release is a function of the quantity released, number of samplers, distance of sampler from source, plume dimensions, height of release, and duration

• GPS systems are now often used to accurately determine sampling locations

Prerequisites for Monitoring

• Prior to monitoring:

(i) Information, techniques and methodologies must be available

(ii) Objectives must be set

• Also:

– Definition of monitoring protocol

– Availability of meteorological and hydrological data

– Availability of emissions data

– Likely pollutant concentrations to be expected

– Availability of equipment

– Availability of analytical techniques

– Definition of suitable environmental quality standards

Prerequisites for MonitoringMonitoring Protocol

• Carefully planned and documented procedures are necessary to ensure reliable and comparable results

• Main components of monitoring protocol?

Prerequisites for MonitoringMonitoring Protocol

(a) Reference methods (sampling and analysis) – may be standard or non-standard

(b) Methodology

– location,

– frequency, duration,

– determinants,

– accuracy required,

– detection limit,

– principles of sampling,

– meteorological and hydrological conditions,

– health and safety,

– access power and security arrangements,

– procedures adopted when standard procedures fail

(c) Quality control procedures which define requirements for:

– calibration of measurement devices, – maintenance of instruments, – sample storage and transport, – data handling and reporting

(d) Quality assurance program to ensure:– measurements are made in accordance

with standard methods– quality control procedures are in place– quality control procedures are being

adhered to– sample ID and routing procedure is well

documented– that the correct reporting procedure is

being used

Prerequisites for MonitoringMeteorological and Hydrological Data

• Care must be taken to ensure data are representative of the area of study

• Wind in particular is susceptible to local interferences

• Portable weather stations and hand-held anemometers may be used

• Lapse rate and inversion height may be obtained with weather balloons

• Turbulence measurements at low-level can be obtained using a bivane and anemometer on a 10 m mast

Prerequisites for MonitoringMeteorological and Hydrological Data

• Reasons for requiring Met Data:

– When fast response measurements are unavailable, may construct time-weighted pollution roses that show how pollutant levels vary with wind direction

– Trajectory of an air parcel over the synoptic-scale may be required for source appointment or dispersion studies (surface pressure field)

• Reasons for requiring hydrological data:

– Tidal range needed for dispersion studies at sea

– Flow and volume data for rivers and lakes (retention times)

Prerequisites for MonitoringSource Inventory

• Cost-effective method of identifying likely pollutants is to look at emissions

• Identify likely pollutants prior to monitoring using emissions data

• Emissions inventory should contain information on:

– Types of source

– Composition of emissions

– Rates of discharge of individual pollutants

• Supplementary information on raw materials, processes and control techniques

• Emissions inventory should be considered a tool and not an alternative to monitoring

Prerequisites for MonitoringSuitability of Analytical Technique

• Pollutants found in environmental compartments over very wide concentration ranges…

Ions Found in Natural Waters

Conc. Range

(mg L-1)

Cations Anions

0-100 Ca2+, Na+ Cl-, SO42

-, HCO3-

0-25 Mg2+, K+ NO3-

0-1 Fe2+, Mn2+, Zn2+ PO43-

0-0.1 Other metal ions NO2-

Reeve, 2002

Ariola et al, 2004


• Several procedures for instrumental analysis are often available

• Considerations affecting choice of method:

– Sensitivity

– Specificity

– Response time

– Response range

– Ease of use

– Ease of calibration

– Cost and reliability

– Precision and accuracy

Hewitt, C.N., 1991


• Precision – reproducibility of analyses

– Measured using separate representative sub-samples

– Measured at intervals during the analysis

• Accuracy – measure of the determinant present

– Measured using international standard reference materials

Prerequisites for MonitoringEnvironmental Quality Standards

• Devised and adopted for many air and water pollutants

• Required for most monitoring programs (not required for source apportionment, historical or fate and transport studies)


• With any standard for environmental quality there may be difficulty in ensuring compliance

e.g. removing contaminants down to EPA safe levels requires new technological developments in water purification

Remote Sensing

• Sophisticated techniques for sensing air and water pollutants

• Use is almost entirely restricted to specialized monitoring exercises

• Aerial photography is an example of a less expensive RS technique

– Conventional color film photography for site surveys

– Monitoring of liquid effluent dispersal using tracer dyes

– Monitoring of oil spills

– Airborne heat-sensing IR equipment used to measure thermal pollution of water

• RS techniques measure light absorption through a section of the atmosphere

• Long pathlengths compensate for low concentrations

Remote Sensing

• Tunable lasers allow long-path absorption measurements of:

SO2, NO2, CO, O3

and OH radical

Remote Sensing

• Light Detection and Ranging (LIDAR) – measurement of backscatter from a pulsed laser – compare backscatter intensity between strong absorption band and weak absorption band

• Similar to RADAR - uses pulsed laser instead of radio waves• Light is scattered by particles providing different absorption paths

– Amount of light returned from each height is proportional to the atmospheric density

– Knowing the speed of light, the time is converted into distance/height – Concentration profile is built over entire range

• DIAL (Differential Absorption LIDAR) uses two wavelengths

– One max (absorbed)– One min (removes background)

Remote Sensing

• Differential Optical Absorption Spectrometry (DOAS) – relates quantity of light absorbed to number of gas moleucles in light beam path – measures many different species in same light beam

Analysis and Presentation of Data

• Organization and summarization of most essential characteristics

• Changes, trends and patterns must be made apparent

• Descriptive and inferential statistics used

• Use of GIS for mapping

Monitoring Summary

• G

References

• Artiola, J.F., Pepper, I.L., and Brusseau, M. (2004) Environmental Monitoring and Characterization. Elsevier, Amsterdam.

• Harrison, R.M. (2006) Introduction to Pollution Science. The Royal Society of Chemistry, London.

• Hewitt, C.N. (ed.) (1991) Instrumental Analysis of Pollutants. Elsevier, London.

• Kegley, S.E. and Andrews, J. (1998) The Chemistry of Water. University Science Books.

• Reeve, R.N. (2002) Introduction to Environmental Analysis. Wiley.• Smol, J.P. (2008) Pollution of Lakes and Rivers: A

Paleoenvironmental Perspective. Wiley-Blackwell.

Air, Water and Land Pollution Chapter 5: Investigating the Environment Copyright © 2009 by DBS.

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Transcript of Air, Water and Land Pollution Chapter 5: Investigating the Environment Copyright © 2009 by DBS.