Lecture 3: Environmental Sampling And Chemical Analysis

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ENGI 9628 – EnvironmentalLaboratoryLecture 3:Environmental Samplingand Chemical AnalysisFaculty of Engineering & Applied Science1

Part One:Fundamentals ofEnvironmental Sampling2

1. ObjectivesThe purpose of environmental sampling is: To determine the background, naturalconcentrations of chemical constituents in theenvironmentTo determine the concentrations of harmfulpollutants in the environment3

2. Environmental Sample Design Planning and sampling protocolsData quality objectives Sampling plan Environmental sampling strategiesWhere and when How many samples 4

(1) Planning and sampling protocolsProject ManagerSampling- Field personnel- Field EngineerLab Analysis-ChemistDataAnalysis Statistician- Geologist- Soil specialistData User- Client- DecisionmakerQA/QC specialistModified from Zhang, 2007. “Fundamentals of Environmental Sampling & Analysis” Wiley5

Data quality objectivesUS EPA 1994 “Guidance for Data Qualitative Objectives” QA/G-46

Sampling planSamples must be “representative”.(Zhang, 2007. “Fundamentals of Environmental Sampling & Analysis” Wiley)7

(2) Environmental sampling strategiesWhere and When? JudgmentalSimple randomStratified randomSystematicOther CompositeTransect8

Judgmental Selection of sampling locations based on professionaljudgment using prior information on the sampling site,visual inspection and/or personal knowledge andexperienceSchedule and budget tight, early stage whenobjective is just screen the areaPrimary representative sampling approach forgroundwater assessmentNo randomization and does not support any statisticalinterpretation of sampling results9

Simple random Arbitrary collection of samples by aprocess that gives each sample unit inthe population the same probability ofbeing chosenAssumes variability of sampledmedium is insignificant – homogenouspopulationApplies for sites with little backgroundinformationNot applicable for heterogeneouspopulationIgnoring prior information leads tomore samplesStatistical analysis of data simpleand straight forward10

Stratified random Sampling population isdivided into several nonoverlapping strataEach strata is morehomogenous than wholepopulationStrata could be temporal orspatialSample size can beadjusted11

Systematic sampling Systematic random subdivides the area into gridsand collects samples usingsimple random samplingSystematic Grid easy toimplementUniform distribution over thespace or time domainCritical part choose rightgrid spacing12

Other Composite samplingSampling cost much less than analytical cost Average concentration rather than variabilitye.g., Trace metal analysis Transect samplingVariation of systematic grid sampling one or moretransect lines across a surface Regular intervals along the transect lines Parallel or non parallel to one anothere.g., characterizing waste piles and water flow 13

Where and when: sampling contaminants In space domain contaminant variations can be in 3dimensions and hence sampling points can be designed by thecoordinates in 1-D, 2-D or 3-DIn time domain there is only one dimension and hencesampling points can be designed in a time period such as days,weeks, months or yearsSpace and time are of interest – both spatial and temporalpatterns of a contaminationObtain representative samples Solids - contaminants accumulates at certain depth Air - wind velocity and direction Water – seasonal variations Biological – different species, size, sex14

Environmental sampling strategiesHow many samples? Largest sample number possibleAvoid taking too few samplesNo Universal formulaSimple random samplingn 4* variability2 / acceptable error215

3. Sampling Techniques General guidelines common to allenvironmental sampling- Sequence of sampling matrices- Sample amount- Sample preservation and storage- Selection of sample containers- Selection of sampling equipments16

(1) Sequence of sampling matricesLeast to most contaminated sampling locations Sediment and water at same site collect water first Sampling at different depths collect surface watersamples first (2) Sample amountSufficient to perform all required laboratory analysesand with an additional amount remaining for QA/QCanalysis Representativeness factor 17

Water/waste water samples- 100 ml for trace metals- 1 L for total organics- 20 40 L for an effluent acute toxicity test Soil/sediment/solid waste samples- 200 g per sample Air samples- Trial and error method- 10 m3 may be required per sample 18

(3) Sample preservation and storage Purpose to minimize any physical, chemical and biological changesfrom time of sample collection to the time of analysis(Zhang, 2007. “Fundamentals of Environmental Sampling & Analysis” Wiley)19

Cold storage reduce metalsolubilityChemical addition orpH change reducemetal adsorption toglass container wallsAnalytical ChangePreservationduring storageobjectMetalsAdsorption to Use plasticglass wallbottles andprecipitation add HNO3 topH 2OilAdsorption to Use glassplasticsbottlesOrganicsBiodegradatio Low pH andntemp; addHgCl2 to killbacteriaModified from Zhang, 2007. “Fundamentals of Environmental Sampling & Analysis” Wiley20

No sample can be storedfor an extended period oftimeASAP6 - 48 h7 - 28dayspHColor(48 h)Oil andMetalsgrease (28days)Maximum Holding Times(MHTs) – Length of time Salinity Chlorophylla sample can be stored(24 -48 h)after collection and prior toDOTurbidityanalysis without(24 h)significantly affecting theanalytical resultsTempe Odor (6 h)ratureSolids(7 d)6 monthsHardnessPesticide(7 d)Total P(28 days)Modified from Zhang, 2007. “Fundamentals of Environmental Sampling & Analysis” Wiley21

(4) Selection of sample containersGlass vs. plastic Headspace vs. no headspace Special containers Biological samples aluminum foil and closedglass containers with inert seals or cap liners Aluminum foils should not be used if mercury isthe target 22

(5) Selection of sampling equipments Made of plastic, glass, Teflon, stainless steel and othermaterials forSurface water and waster water samplingGroundwater samplingSoil samplingSediment samplingHazardous waste samplingBiological samplingAir and stack emission sampling23

4. Environmental Sampling(1) Soil sampling Soft surface soil samples– scoop or trowel1 10 ft – tube sampler3 inches 10 ft –augersamplerWill disrupt and mix soilhorizonsHard soils – split spoonsampler24

(2) Surface water and waste water samplingPond sampler - near shore sampling weighted bottle sampler - collect samples in awater body at a predetermined depth Kemmerer bottle – Teflon, acrylic or stainlesssteel tube attached to a rope and best used whenaccess is from a boat or structure such as bridgeor pier 25

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(3) Ground water samplingCollected from a well by a bailer Bailer – an open pipe with an open top anda check valve at the bottom. Peristaltic pump – rotor with ball bearingrollers Well – with a small diameter and has adepth limitation of 25 ft 27

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(4) Sediment samplingScoops and trowels – for sample sedimentsaround shoreline and slow moving waters Ekman dredge – small and light weight (10 lbs)and collects soft sediments Petersen or Ponar dredges 29

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(5) Hazardous waste samplingPonar or Ekman sampler – sludgesampling Composite liquid waste sampler –stratified liquid in drums and other similarcontainers Thief – drum sampling device particularlyuseful for grain like materials Trier – sampling sticky solids andloosened soils 31

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(6) Biological samplingUnique and diverse equipments Mammals – trapping Fish – trawl nets gill nets Vegetation – harvested during growing season Benthic macro invertebrate samples – Petersenand Ekman dredges can be used 33

(7) Air and stack emission sampling Direct reading instruments and type of monitoringinstrumentsExpensive and complex techniquesProfessional stack – testing firmsHigh volume, total suspended particle (TSP)sampling systemPM-10 sampling system34

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5. Quality Assurance/Quality ControlStandard Methods- EPA Methods for Air, Water, Wastewater and Hazardouswaste- SSSA for soilProject point of view Objectives for accuracy, precision Sampling & custody Analytical procedures Calibration (when, how) Data analysis & management Corrective action plan 36

Part Two:Environmental Chemical Analysis37

1. Water Analysis TurbidityColorpHAcidity/AlkalinityHardnessResidual Chlorine and ChlorineDemandDissolved OxygenBiochemical Oxygen DemandChemical Oxygen DemandSolids3838

(1) Turbidity Result of interference of passage of light through thewater containing suspended materialsTurbidity determinationNephelometer scattering of light from particlesTurbidimeter interference to light passage in astraight lineNTU is commonly usedSamples with turbidities 40 NTU must be diluted3939

Schematic diagram of a turbidimeter and a nephelometer(Zhang, 2005. “Chemistry for Environmental Engineering” )40

(2) Color Apparent color caused by suspended matter determined on the sample “as is”True color caused by colloidal vegetable ororganic extracts remove suspended matter bycentrifugation then determine color of clarified liquid1 standard unit of color 1 mg/L of Pt (as K2PtCl6)Nessler tubes 0 70 color unitsColor-comparison tubes (Nessler tubes)(Zhang, 2005. “Chemistry for Environmental Engineering” )41

(3) pH and acidity/alkalinity pH condition of a solution related to [H ]pH - log[H ] determined by a pH meterAcidity/Alkalinity the ability of natural water toneutralize base/acid determined from a titrationAcidity (Volume need to reach end point) (concentration of the strong base)Mineral acidity [H ] [H2CO3] [OH-] titration to pH 3.7 (methyl orange end point)Total acidity [H ] 2[H2CO3] [HCO3-] [OH-] titration to pH 8.3 (phenolphthalein end point)42

Alkalinity (Volume need to reach end point) (concentration of the strong acid) titrated with 0.02 NH2SO4Phenolphthalein alkalinity (mg/L) [OH-] [CO32-] [H ] titration to pH 8.3Total Alkalinity Bromcresol-Green alkalinity (mg/L) [HCO3-] [OH-] 2 [CO32-] [H ] titration to pH 4.5End points for Acidity/Alkalinity titration(Zhang, 2005. “Chemistry for Environmental Engineering” )43

(4) Hardness Hardness caused mainly by divalent metallic cations (e.g.Ca2 , Mg2 , Sr2 , Fe2 , Mn2 ) determined by EDTAtitrimetric methodEDTA ethylenediaminetetraacetic acid (H4Y)M2 EDTA [M-EDTA]complexTotal hardness Ca hardness Mg hardness (in most cases)(Zhang, 2005. “Chemistry for Environmental Engineering” )44

(5) Residual chlorine Chlorine (Cl2) used for disinfection of water supplies andwastewater effluent to prevent water-borne diseasesFree chlorine residuals Cl2 HOCl OCl Combined chlorine residuals NH2Cl NHCl2 NCl3Total chlorine residuals free chlorine residuals combined chlorine residualsMeasurement of total chlorine residualsCl2 2 I I2 2 Cl I2 starch blue colorI2 2Na2S2O3 2Na2S4O6 2NaI45

(6) Dissolved oxygen The concentration of DO in water is small andtherefore precarious from ecological point of view.The dissolution processO 2 (gas) O 2 (dissolved) The equilibrium constant is the Henry’s Law constantKHO (dissolved)KH 2Partial PressureO2DO analysis the Winkler Method4646

DO: Thermal pollution River and lake water that has been artificially warmedcan be considered to have undergone ThermalPollution. Why?Gas solubility decreases with increasing temperature.Warm water contains less oxygen than cold water. Tosustain life, most fish species require at least 5 ppm ofDO.Consequently, their survival in warm water can beproblematic.47

(7) Biochemical oxygen demand (BOD) BOD: amount of O2 required by bacteria to stabilizedecomposable organic matter under aerobicconditionsHigh BOD value high organic-matter concentration poor water qualityDecomposition of organic matter is a slow process20 days decompose 95 to 99%of organic matter5 days decompose 60 to 70%of organic matter4848

Measurement of BOD BOD5 BOD5 DO5-DO0where DO0 DO before incubation (day 0)DO5 DO after 5 days of incubation at 20ºC(day 5) BOD5 for domestic sewage several hundreds mg/L BOD5 for industrial sewage several thousandsmg/L when the sewage is discharged to water quickdepletion of oxygen 49

(Zhang, 2005. “Chemistry for Environmental Engineering” )initial stage DO curve drops (i.e. rate of O2 consumption bybacteria rate of reaeration with atmosphere) at the point where [DO] minimum rate of consumption rate of reaeration beyond minimum point rate of consumption rate of reaeration (DO leveleventually returns to normal)This sequence is called "natural self-purification of water"50

(8) Chemical oxygen demand (COD) COD a measure of total organic strength of wastesThe basis for the COD test nearly all organic compounds canbe fully oxidized to carbon dioxide with a strong oxidizing agentunder acidic conditions.COD determination potassium permanganate (KMnO4) wasused for years potassium dichromate (K2Cr2O7) becomes themost effective oxidant now (it is relatively cheap, easy to purify,and is able to nearly completely oxidize almost all organiccompounds)CnHaObNc d Cr2O72 (8d c) H n CO2 [(a 8d 3c)/2] H2O c NH4 2d Cr3 where d 2n/3 a/6 c/25151

(9) Residue (Solids) Usual definition of solids residue upon evaporation anddrying at 103 105 ºC5252

2. Soil Analysis Physical properties Particle sizeDensityPorosityTexture Chemical analysis Soil pHSoil organic matterCation exchange capacitySoil contaminants Heavy metals (e.g. Pb, Cd, Cr)Organic pollutants (e.g. Pesticides, Petroleumhydrocarbons)53

(1) Soil particle sizeSandSiltClay2 µmFine20 µmCoarse200 µmSoilGravel2.0 mmNon-soil54

(2) Soil density Soil particle density 1 g/mL for organic matter, 5 g/mL forsome metals oxides; average 2.5 2.8 g/mL Soil bulk density Includethe pore spaces between particles Smaller than particle density; average 1.2 1.8 g/mL55

(3) Porosity and texture PorosityPore space (%) 100 (bulk density/particledensity)*100 Texture ClaySandSilt(Zhang, 2005. “Chemistry for Environmental Engineering” )56

(4) Soil pH How acidic or alkaline thesoil is0 to 14pH -log [H ]At pH 6 there are 10xmore H than at pH 7At pH 5 there are 100xmore H than at pH 757

(5) Soil organic matter Soil organic matter includes Humic substances (humicacid, fulvic acid, and humin) Fats, resin, and waxes Polysaccharides Amino acidsMain constituentsC (52 - 58 %), O (34 – 39 %),H (3.3 – 4.8 %) and N (3.7 –4.1 %) with other prominentelements being P and SSoil TypeOrganic MaterContentAgriculturesoils1–5%Forest soils 10 %Peat Soils 20 %58

(6) Cation exchange capacity Capacity of a soil exchange ofpositively charged ions between thesoil and the soil solutionSoil TextureClay particles and organic matterhave negatively charged sites thatSandscan hold positively charged ions ontheir surfacesLoamsExpressed in meq/100g of soilSilt loams1 m eq of CEC has 6.02 1020adsorption sitesClay and clayCEC of most soils increases with anloamsincrease in soil pHOrganic soilsHighly dependent upon soil textureand organic matter contentCEC(meq/100g soil)3 - 2010-1515 - 2520 - 5050 - 10059

(7) Soil contaminants Inorganic contaminants(e.g. heavy metals) AAS or AES analysisOrganic contaminants(e.g. Petroleumhydrocarbons andpesticides) GCanalysis60

Part Three:Information Sources onEnvironmental Sampling andAnalysis61

Water/Soil /Sediments Sampling andAnalysis US EPA Office of Water Analytical Methods onlineUS EPA's SW-846 Online Test Methods for Evaluating Solid Waste Physical/Chemical Methods- all approved methods and draft update IV are availableUS EPA Technical Support Centre for Monitoring and Site Characterisation and NationalLaboratory Accreditation ProgrammeFAQ's on Oil & Grease analysis from US EPACanadian sampling strategy for Sediments, Fresh Water and Effluent, Lake Sediments,StormwaterUSFDA Pesticides, Metals, Chemical Contaminants & Natural ToxinsGuidelines for Soil SamplingFAQ's about Soil and Plant AnalysisDOE Methods for Evaluating Environmental and Waste Management SamplesEnvironmental analysis techniques from the Association of Official Analytical ChemistsFree software for Environmental Sampling from American Chemical SocietyUS source on Bethnic Macroinvertebrate IdentificationUS EPA on Biological Indicators and Bethnic Macroinvertebrate identificationCanadian information on Biological Sampling, Invertebrate Sampling, Fish and Fish Tissue,Algae, Microbiology, Aquatic Pathogens, Aquatic Plants and WeedsCanadian Water Sampling ManualsUS Source on Environmental SOPsHow to carry out ecological sampling62

Air Sampling and Analysis US based OSHA Manual on Personal Air Sampling, Sampling for SurfaceContaminants, Sample Shipping and Handling, indoor air qualityinvestigationsNIOSH Manual of Analytical MethodsAir sampling information on the SKC Website with Sampling GuidesUS EPA Ambient Air Monitoring Information, air toxics methods,inorganics methods, open path analysers, air pollution training institute,index to EPA test methodsFast Analysis of Hazardous Organics in Fire and Chemical Accidentsby Mobile GC/MSWORKPLACE ATMOSPHERES - GENERAL REQUIREMENTS FORTHE PERFORMANCE OF PROCEDURES FOR THE MEASUREMENTOF CHEMICAL AGENTS INTERNET AND OTHER SOURCES OFMETHODS FOR THE ASSESSMENT OF WORKPLACE AIRQUALITY63

Laboratory Quality Control OECD Series on Principles of GoodLaboratory Practice and ComplianceMonitoringUK based Aqua check InternationalProficiency Testing for Chemical AnalyticalLaboratories64

Environmental Quality Standards US EPA Water Quality CriteriaUS EPA Air information including Ambient AirQuality StandardsNetherlands - Contaminated Land at the Ministry ofHousing, Spatial Planning & Environment,Contaminated Land Guidance and ContaminatedLand Tables of ValuesUS EPA soil screening guidelinesUS survey of Soil and Groundwater Clean-upStandards65

Lecture 3: Environmental Sampling and Chemical Analysis 1 . Part One: Fundamentals of Environmental Sampling 2 . 1. Objectives . Critical part choose right grid spacing 12 . . (1) Soil sampling .

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