Rainfall Quality in Portland, Oregon

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Rainfall Quality in Portland, Oregon

• Lacey Sullivan
• Master in Environmental Management
• Portland State University
• ACWA SW Committee Meeting
• January 17, 2006

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Objectives

• To evaluate the importance of precipitation as a
  non-point source of pollutants
• To compare precipitation quality among land uses
• To evaluate potential sources of pollutants
  within the Portland area
• To evaluate the amount of pollutants entering
  stormwater from precipitation

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Factors Affecting Precipitation Quality

• Land uses
• Importance of urban areas
• Meteorological conditions
• precipitation amount
• wind direction
• Spatial patterns
• geographical location
• topography
• vegetation type
• Distant sources

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Study Area

• 16 sites throughout Portland within 4 nominal
  land use categories
• Commercial
• Industrial
• Open Space
• Residential

http//www.ohwy.com/or/p/portland.htm
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Field Sampling Methods

• Five storm events sampled
• December 2004 June 2005
• Samples collected using 12.6 diameter funnel
  attached to 2L bottle
• Deployment 12 hours prior to predicted storm
  event
• Attached at each site
• Duplicates
• Retrieval 12 to 24 hours after storm event

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Rainfall Collector Installation
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Laboratory Analysis

• pH and conductivity measured in field
• NH3, Total P, Cu, Pb, Hg, Zn measured in lab (BES
  Water Pollution Control Laboratory)
• Standard EPA analytical methods
• Rationale for choosing analytes
• Important stormwater pollutants
• No special sampling techniques required (unlike
  organics)
• Detections in rainwater expected

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Data Analysis

• Basic statistics on data
• Land Use Analysis
• Differences in concentrations between land use
  categories across all events
• Event Analysis
• Differences in concentrations between events
  across all land uses and within each land use
  category
• Site Analysis
• Differences in concentrations between sites
  within each land use category
• ANOVA or Kruskal-Wallis
• Pairwise Comparisons

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Ammonia
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Ammonia

• Concentrations within commercial and industrial
  significantly higher than within open space and
  residential
• Proximity to an urban area important for wet
  deposition of NH3
• Transportation emissions and emissions from
  industrial activity
• NH3 emission sources within Portland
• Primarily highway vehicles
• Fuel combustion, waste disposal/recycling,
  off-highway vehicles, misc. sources

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Total Phosphorus
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Total Phosphorus

• Concentrations within open space and residential
  significantly higher than within commercial
• General sources of P
• urban sites influenced by industrially-associated
  P loadings
• rural and suburban sites influenced by localized
  application of P-containing fertilizers
• Results in Portland appear to suggest importance
  of influence of P-containing fertilizers

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Copper
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Copper

• Concentrations within industrial significantly
  higher than within all other land uses
• Primary source of copper in the air due to copper
  dust generated by copper processing operations in
  industrial areas
• Other sources include fuel combustion, burning,
  brake pads, pesticides
• According to EPA, industrial sources of copper
  emissions important in Portland

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Lead
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Lead

• Concentrations within industrial significantly
  higher than within all other land uses
• Primary source of lead in the atmosphere is due
  to industrial activities
• Mining, smelting and refining, manufacture of
  products, metal works, incinerators of waste
• Point sources/facilities account for 80 of
  total emission sources in Portland

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Mercury
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Mercury

• Concentrations within industrial significantly
  higher than within commercial
• High amounts of mercury released from industrial
  activities (20,000 tons/yr)
• Incinerators, electric utilities, waste
  combustors, coal-fired boilers
• Higher amounts released through natural degassing
  of the earths crust (25,000 to 150,000 tons/yr)
• Point sources/facilities account for 95 of
  total emission sources in Portland

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Zinc
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Zinc

• Concentrations within industrial higher than
  within open space and residential
• Primary source of zinc is due to industrial
  activities
• Galvanize metals, rubber industry, zinc oxide in
  paints, die castings by automotive industry
• According to EPA, industrial sources of zinc
  emissions important in Portland

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Summary of Results

• Differences in concentrations between pairs of
  land uses for all analytes except pH and
  conductivity
• NH3 higher within industrial and commercial areas
  than open space and residential
• Total P higher within open space and residential
  areas than commercial
• Heavy metals generally higher within industrial
  areas than other land uses

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Summary of Results

• Differences between events
• Event 4 concentrations significantly lower than
  concentrations during other events
• Differences between sites within land use
  categories
• Industrial example with heavy metals
• Columbia site
• Open space example
• Powell Butte site

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Stormwater Dataset

• Stormwater data collected 2000 2005
• Combination of grab samples from UIC program and
  flow-weighted from BMP effectiveness studies
• Small dataset (lt30 data points) for each land use
• Median concentrations typically smaller than in
  1996 ACWA dataset, especially for dissolved
  fraction

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Comparison to StormwaterTotal Stormwater to
Total Rainfall Concentrations
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Results of ComparisonsTotal Stormwater to Total
Rainfall Concentrations

• In residential land use, concentrations in
  rainfall are about 50 of stormwater
• In industrial and commercial land use, ratios are
  much larger, indicating source other than
  atmospheric are dominant
• Total mercury ratio for all land use indicate the
  predominance of atmospheric sources

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Comparison to StormwaterDissolved Stormwater to
Total Rainfall Concentrations