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Spatiotemporal Analysis ofSpatiotemporal Analysis ofSurface Water Surface Water
Tetrachloroethene in New Tetrachloroethene in New JerseyJersey
Presentation of the project of Presentation of the project of Yasuyuki AkitaYasuyuki Akita
Temporal GIS Fall 2004Temporal GIS Fall 2004
About TetrachloroetheneAbout Tetrachloroethene
About TetrachloroetheneAbout Tetrachloroethene
• Tetrachloroethene: CTetrachloroethene: C22ClCl44• Volatile organic compoundVolatile organic compound
• Nonflammable colorless liquid at Nonflammable colorless liquid at room temperatureroom temperature
• Ether-like odorEther-like odor
• Synonym: Tetrachloroethylene, Synonym: Tetrachloroethylene, Perchloroethylene, and PCEPerchloroethylene, and PCE
Use and ProductionUse and Production
• Mainly Used for dry cleaning, chemical Mainly Used for dry cleaning, chemical intermediates, and industrial solventintermediates, and industrial solvent
• PCE used in dry cleaning industry has PCE used in dry cleaning industry has been declining during 90sbeen declining during 90s
• Recent Demand: 763 million lb (1980) Recent Demand: 763 million lb (1980)
318 million lb 318 million lb (1999)(1999)
Exposure pathwayExposure pathway
• Primary routePrimary route– InhalationInhalation– Ingestion of contaminated food and waterIngestion of contaminated food and water
• Widely distributed in environmentWidely distributed in environment– 38% of surface water sampling sites in the 38% of surface water sampling sites in the
U.S.U.S.– 771 of the 1430 National Priorities List sites771 of the 1430 National Priorities List sites– 154 of 174 surface water samples in N.J. 154 of 174 surface water samples in N.J.
(1977~1979)(1977~1979)
Health Effect of Health Effect of TetrachloroetheneTetrachloroethene
• Acute Effect (inhalation exposure)Acute Effect (inhalation exposure)– Dizziness, headache, sleepiness, Dizziness, headache, sleepiness,
confusion, nausea, difficulty in speaking confusion, nausea, difficulty in speaking and walking, unconsciousness, and and walking, unconsciousness, and deathdeath
• Chronic Effect (oral/inhalation Chronic Effect (oral/inhalation exposure)exposure)– Detrimental effect to kidney and liverDetrimental effect to kidney and liver
CarcinogenicityCarcinogenicity
• Reasonably anticipated to be a human Reasonably anticipated to be a human carcinogen (US DHHS)carcinogen (US DHHS)
• Group 2A (Probably carcinogenic to Group 2A (Probably carcinogenic to humans) (IARC)humans) (IARC)
• Animal studies: tumors in Animal studies: tumors in liverliver and and kidneykidney
Quality Standard for Quality Standard for TetrachloroetheneTetrachloroethene
• Maximum Contaminant Level (MCL) Maximum Contaminant Level (MCL) in drinking water - 0.005 mg/Lin drinking water - 0.005 mg/L
• Surface Water Quality Standard in Surface Water Quality Standard in New Jersey - New Jersey - 0.388 μg/L
N.J. adopted more stringent standardN.J. adopted more stringent standard
Monitoring DataMonitoring Data
Monitoring Dataset for New Monitoring Dataset for New JerseyJersey
• Data SourceData Source– NJDEP/USGS Water Quality Network NJDEP/USGS Water Quality Network
WebsiteWebsite– EPA STORET databaseEPA STORET database
• Data used in this studyData used in this study– 369 measured values369 measured values– 171 monitoring stations171 monitoring stations– From 1999 to 2003From 1999 to 2003
Monitoring Data – HistogramMonitoring Data – Histogram
Raw DataRaw Data Log-Transformed Log-Transformed DataData
Monitoring Data – Statistical Monitoring Data – Statistical MomentsMoments
RawRaw
((μμg/L)g/L)Log-Log-
transformedtransformed
(log-(log-μμg/L)g/L)
# # of recordsof records 369369 369369MeanMean 0.1569650.156965 -2.597410-2.597410
Standard Standard DeviationDeviation
0.3042710.304271 1.0437571.043757
Coef. of Coef. of skewnessskewness
5.2128345.212834 1.1191871.119187
Coef. of kurtosisCoef. of kurtosis 39.50591239.505912 4.0806464.080646
Distribution of Data PointsDistribution of Data Points
Distribution of Data PointsDistribution of Data Points
Distribution of Data ValuesDistribution of Data Values
What we want to know is …What we want to know is …
• Challenge of our researchChallenge of our research– Assess all river reachesAssess all river reaches– Taking into account the space/time Taking into account the space/time
variabilityvariability
Framework for the space/time Framework for the space/time estimationestimation
Bayesian Maximum Entropy (BME) analysis of Bayesian Maximum Entropy (BME) analysis of TGISTGIS
Covariance for Residual Covariance for Residual S/TRFS/TRF
22
22
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3exp
3exp
3exp),(
2
aa
rc
aa
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days 2000
deg. 25.0
1766.0
days 1700
deg. 30.0
8832.0
2
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Covariance for Residual Covariance for Residual S/TRFS/TRF
BME Estimation – Temporal BME Estimation – Temporal FluctuationFluctuation
BME Estimation – Spatial BME Estimation – Spatial DistributionDistribution
BME Estimation – Spatial BME Estimation – Spatial DistributionDistribution
BME Estimation – Spatial BME Estimation – Spatial DistributionDistribution
(Apr. 15, (Apr. 15, 2002)2002)
BME Estimation – Contaminated BME Estimation – Contaminated AreaAreaArea above the quality standard: 0.388μg/LArea above the quality standard: 0.388μg/L
BME mean estimateBME mean estimate
Upper bound of the BME 68% confidence Upper bound of the BME 68% confidence interval interval
Upper bound of the BME 95% confidence Upper bound of the BME 95% confidence intervalinterval
(Apr. 15, (Apr. 15, 2002)2002)
BME Estimation – Along River BME Estimation – Along River StreamStream
• Equidistance points Equidistance points along river streamalong river stream– More accurate More accurate
estimation for estimation for surface water surface water
BME Estimation – Along River BME Estimation – Along River StreamStream
MeanMean 68% CI68% CI 95% 95% CICI
Feb. 5, 2000Feb. 5, 2000 0.79%0.79% 1.48%1.48% 15.03%15.03%Mar. 11, Mar. 11, 20012001
0.98%0.98% 6.86%6.86% 66.96%66.96%
Apr. 15, Apr. 15, 20022002
1.50%1.50% 9.04%9.04% 69.63%69.63%
May 20, May 20, 20032003
0.59%0.59% 3.24%3.24% 46.08%46.08%
• Fraction of river miles that does not Fraction of river miles that does not attain the quality standardattain the quality standard
Fraction of River MilesFraction of River Miles
Identifying Contaminated Identifying Contaminated WMAsWMAs• The state of New Jersey is divided into The state of New Jersey is divided into
20 20 Watershed Management Area Watershed Management Area (WMA)(WMA)
• Assess which part of the state is Assess which part of the state is contaminatedcontaminated
• Contribution of each WMA to the Contribution of each WMA to the fraction of river miles assessed as fraction of river miles assessed as – Highly Likely in Non-AttainmentHighly Likely in Non-Attainment– More Likely Than Not in Non-AttainmentMore Likely Than Not in Non-Attainment
Contribution of WMAsContribution of WMAs
• Highly Likely in Non-AttainmentHighly Likely in Non-Attainment
Contribution of WMAsContribution of WMAs
• More Likely Than Not in Non-More Likely Than Not in Non-AttainmentAttainment
Fraction of River Miles in Fraction of River Miles in WMAsWMAs
ConclusionConclusion
ConclusionConclusion
• About Monitoring DataAbout Monitoring Data– Some high concentration values are Some high concentration values are
observed in New Jersey between 1999 to observed in New Jersey between 1999 to 2003.2003.
– Monitoring data shows high Space/Time Monitoring data shows high Space/Time variability in terms of location of the variability in terms of location of the monitoring point and monitoring valuemonitoring point and monitoring value
• Application of BME method of TGISApplication of BME method of TGIS– It enables us to take into account high It enables us to take into account high
space/time variability and to estimate space/time variability and to estimate the concentration all river reachesthe concentration all river reaches
ConclusionConclusion
• New CriterionNew Criterion– New criterion takes into account the New criterion takes into account the
uncertainty information of posterior PDFuncertainty information of posterior PDF– It is used to complementary criterion for It is used to complementary criterion for
the conventional onethe conventional one– Fraction of the river miles assessed as Fraction of the river miles assessed as
“Highly Likely in Non-Attainment” “Highly Likely in Non-Attainment” reached about 0.45% in 2000reached about 0.45% in 2000
– Fraction of the river miles assessed by Fraction of the river miles assessed by the conventional criterion (More Likely the conventional criterion (More Likely Than~) reached about 1.8% in 2002Than~) reached about 1.8% in 2002
ConclusionConclusion
• Model ComparisonModel Comparison– Space/Time analysis produces more Space/Time analysis produces more
accurate estimation than the conventional accurate estimation than the conventional purely spatial analysispurely spatial analysis
– Space/Time analysis produced very Space/Time analysis produced very different estimatedifferent estimate
– In purely spatial analysis, non-assessment In purely spatial analysis, non-assessment river miles reach about 99%river miles reach about 99%
• NJ DEP will be able to better assess NJ DEP will be able to better assess PCE concentration in all river reaches PCE concentration in all river reaches by using this method and new by using this method and new criterioncriterion