Surface Water Mercury

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Surface Water Mercury

• Group 1
• P.N. Drummey
• E.J. Kelly
• A.G. Parks
• November 28, 2006
• ENVR 468

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Overview

• Background
• Sources and Transport of Mercury
• Regulatory Requirements
• Methods
• Collection of data and data sources (2001-2006)
• Data-area collaboration with Group 2
• Determination for hard and soft data
• Estimations Results
• Covariance of spatial and temporal data
• Maps of East coast mercury concentration in
  surface water
• Discussion
• Trends seen in mercury data
• Detection limits
• Possible implications from research

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Background(Sources)

• Natural sources
• Natural Deposits in soils and rocks
• Volatilization from oceans
• Volcanoes
• Anthropogenic sources
• Solid waste incineration and solid waste leaching
  (batteries, thermometers)
• Fossil-fuel consumption (coal combustion)
• In fertilizers and fungicides
• Chlorine Alkali processes (Pulp and paper mills)
• Metal processing

• Info from EPA factsheet http//www.epa.gov/waters
  cience/fishadvice/mercupd.pdf

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Background(Sources)

• Three main forms of mercury
• Inorganic forms Hg(II) and Hg(I)
• Methylmercury (Most toxic to mammals)
• Subtle to sever neurological effects
• From fish consumption
• Impaired vision, loss of motor-coordination,
  seizures, death
• Potential human germ cell mutagenicity
• Kidney damage
• Bioaccumulation (intake faster than body process)
• Humans ½ body burden eliminated in 70 days
• Biomagnification (incremental increase in conc at
  each level)
• Concentrates in muscle tissue of fish -gt skin
  fat

• Info from EPA factsheet http//www.epa.gov/waters
  cience/fishadvice/mercupd.pdf

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Transport Overview

• Evaporates from soil and surface waters into
  atmosphere and can be re-deposited
• Mercury enters water in an inorganic form (Hg2)
• Transformed to by methylating bacteria to
  Methylmercury
• 90-100 of mercury in fish is Methylmercury
• Mobility of mercury in aquatic systems is
  affected by pH and DOC

All information from http//water.usgs.gov/wid/FS_
216-95/FS_216-95.html
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Regulatory Requirements

• Federal Water Pollution Control Act 1972
• Clean Water Act - 1977
• Safe Drinking Water Act - 1974
• EPA water quality criteria (protect human health)
• Drinking water
• Max Contam Level Goal (MCLG) -gt 2 ppb
• Max Contam Level (MCL) -gt 2 ppb
• Ambient Water Quality - Priority Pollutant
• Max Conc Fresh- 1.4 ppb Salt- 1.8 ppb
• Contin Conc 0.77 ppb 0.94
  ppb
• Methylmercury Criterion
• 0.3 mg CH3Hg / kg fish tissue

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Research Objectives

• Perform a mapping analysis of mercury in the
  freshwaters of North Carolina and the surrounding
  east coast area (PA to SC)
• Determine spatial and temporal trends in mercury
  data
• Focus on bodies of water with most relevance to
  human health

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Methods

• Data Collection and Organization
• USEPA for East Coast states
• Supplemental data from USGS
• Many below detection level data points
• Rounded to 0.5 degree areas for North Carolina
• Eliminated from data for other states
• Analyzed and mapped using ArcBME and ArcGIS

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Methods

• 35 of data points are hard
• Outliers are 16 values from TN reported as 10
  mg/L

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Results Data Analysis

• Log-transformed distribution

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Results Spatial Distribution
North Carolina
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Results Covariance Analysis
c01 3.5 (log-ng/L)2 ar14 deg at190
months c02 1.0 (log-ng/L)2 ar25 deg at220
months c03 0.5 (log-ng/L)2 ar14 deg, at190
months ar25 deg, at220 months
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Results Covariance Analysis

• Spatial
• Gaussian, sill4.5, range 4
• Exponential, sill 0.5, range 5
• Temporal
• Exponential, sill 3.5, range 90
• Exponential, sill 1.5, range 20

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Results Temporal Estimation

• Possible seasonal variability?

• Data less variable in other areas

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Results Spatial Estimation
Month 5Month 6Month 25
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Possible Sources of Error

• Different detection levels for different states
• Different methods
• Older method used in North Carolina (with higher
  detection limits)
• Only used data from EPA STORET
• Large variance in eastern Kentucky and
  Northeastern Virginia
• Few data points for Pennsylvania, Virginia Ohio

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Discussion Fish Consumption Hazards

• Freshwater fish high in mercury
• Blackfish (bowfin)
• Advisory issued for all of NC in 1997
• Catfish (caught wild)
• Jack fish (chain pickerel)
• Largemouth bass (statewide)
• Warmouth

High mercury levels have been found in Blackfish
(bowfin), catfish, Jack fish (chain pickerel),
and Warmouth caught south and east of Interstate
85.
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Discussion North Carolina

• 41 states have issued 2,242 fish advisories as of
  December 2000
• 17 in North Carolina
• From BME estimates
• Nashville, TN
• Pittsburg, PA
• Colombia, SC
• Huntington, WV
• Jordan Lake and University Lake
• Drinking water sources for Cary and Chapel Hill
  areas
• Low levels of mercury for all of NC (lt0.07 ug/L)
• Fish
• Bass, crappie, catfish, panfish, blue gills
• Currently no mercury advisories for North
  Carolina fish

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Questions ??