With emphasis on recent work TNO

1
With emphasis on recent work _at_ TNO

• Improvements to metal emission estimates

2
Contents

• Background
• Case I - Metal contents of diesel and petrol fuel
  
• Conclusions fuel analysis
• Case II - Copper from brake wear
• Implications for EF guidebook?
• Outlook

3
Background (heavy) metals (HM)

• Elevated presence and availability of HM in
  ecosystems and the urban environment due to human
  activities
• HM (e.g. lead, cadmium) are toxic causing adverse
  health effects
• Main anthropogenic sources of heavy metals are
  Industrial sources (e.g., mining activities,
  foundries and smelters) Diffuse sources (e.g.,
  combustion by-products, traffic, etc..)
•  Considerable attention over the last decades
  (Pb, Hg, Cd)
• In recent years two European HM inventories TNO
  (Denier van der Gon et al.) and ESPREME (Reiss et
  al.) both presented at TFEIP meetings in 2005
  2006.

4
Issue Current knowledge is not able to explain
the ambient concentrations of many heavy metals
(60-75 explained).
Comparison of modelled and measured lead
concentrations in air using official/ TNO (blue)
and ESPREME (red) emissions. Natural and
historical emissions are included.
Source Sliggers et al. (2007)
5
Lead emission in the UK from 1970 to 2004 (t/yr)
for road transport and other sources
(correction for potential resuspension of Pb
containing dust, and necessary emission input to
explain observed concentrations (black line)
Major Pb emission Reduction! ?
But gap increases! Still Pb in fuels?

• Source Dore et al., (2006)

6
Case I - Pb in petrolThe problem

• Leaded fuels have been used for a long period,
  clear adverse health effects have been reported.
  As a result leaded fuels have been banned in
  Europe.
• Lead emission from unleaded road transport fuel
  combustion has been suggested as a missing source
  to explain the discrepancy between measured and
  modeled Pb concentration in air (Pacyna et al.,
  Atmospheric Environment 2007, 41 8557-8566.)
• Reason Pb is present in the crude and even Pb
  contents below the EC limit value (lt5mg/l) can be
  a significant source give the large quantities of
  petrol consumed
• Is this realistic?

7
Study Metal contents of diesel and petrol fuel
sold on the European Market

• Objective to obtain high quality analytical data
  on the concentrations of dissolved metals in
  petrol and diesel as sold in nine European
  countries.
• Methodology Fuel samples collected at service
  stations - The distribution of fuel samples
  selected by CONCAWE with sensitivity to various
  issues in different Member States, including
• Petrol and diesel fuel consumption (also as of
  EU-27),
• Penetration of biofuel components,
• Extremes in climactic conditions, and
• Supply and distribution logistics.

Reference Denier van der Gon et al., Metal
contents of diesel and petrol fuel sold on the
European Market, TNO report 2009 Final draft
submitted to CONCAWE, status not final yet.
8
Fuel consumption in the covered countries
represents over 80 of the consumption in the
EU-27.
9
Metals analyzed in transport fuels

• AQ interest defined as included in UNECE HM
  Protocol
• Metals outside AQ interest not further discussed
  here
• Note Finnish data not included in presented
  results due to possible contamination coverage
  of EU petrol and diesel still gt 80

10
Just to prove we do have instruments ?
Inductively coupled plasma mass spectroscopy X2
QAPEX ICP-MS
11
Examples of results - I

• Dot average value the bar indicates high-low
  value (range)
• All Pb values in ppb (ug/kg) range!
• The Pacyna et al. paper (AE, 2007) used mg/kg
  range overestimated!

12
Examples of results - II

• Considerable range in Cu values but average
  values are below 10 ug/kg
• Note guidebook EF is currently 1700 ug/kg (to be
  discussed later)

13
Average metal content of transport fuel by country
Diesel
Petrol

• All concentrations in ppb (ug/kg) range
• No specific country pattern
• Petrol slightly higher than diesel but
  essentially comparable

14
Summary Average metal contents in EU
Implications? To be discussed
Concentrations of the priority heavy metals (Cd,
Hg, Pb) and other metals (As, Cu, Cr, Ni, Se and
Zn) listed in the UNECE Heavy metal protocol in
road transport fuels are currently low (below 10
ug/kg), Zn is slightly elevated but still low
15
Case II Brake wear, an important source for
particulate copper

• Brake wear generates brake lining particles,
  which were until now not accounted for in
  emission inventories for copper because EFs were
  old and based on asbestos brake pads.
• We assessed the importance of brake wear to
  explain atmospheric copper concentrations.
• We also used preliminary fuel analysis
  measurements to reassess the EF for transport
  fuel combustion
• Conclusion fuel combustion no longer important,
  brake pads are dominating source in EU

Reference Denier van der Gon et al., A revised
estimate of copper emissions from road transport
in UNECE-Europe and its impact on predicted
copper concentrations, Atmospheric Environment,
Volume 41, 8697-8710, 2007
16
Copper content of brake pads and linings
This type of data combined with brake wear PM
emission factors gives the emission of your
component of study (here copper) Elevation
should be visible in vicinity of the source
17
Copper concentration of ambient PMconfirms
source relevance
?
18
Implications for guidebook?Please join the
discussion!

• Road transport wear emissions are important metal
  sources review of literature for al HM is
  relevant. (Updates may be needed e.g., because
  of change in materials)
• Guidebook EF for exhaust is expressed in ug/kg
  fuel but
• EF EF_f(uel) EF_m(otor oil burning)
  EF_e(ngine attrition)
• EF_f low High EFs for e.g. Cu and Zn do not
  originate from fuels and EF_m EF_e are
  independent of fuel
• So, LPG is no different from petrol and diesel?
• Few measurements available for HM in exhaust PM
  (Vouitsis et al., 2007) direct quantification
  ( -gt low Pb, Cu substantial Zn, Fe and Sb
  depending on lube oil and driving cycle)
• This information should be combined with
  information on EF_m and EF_e to better understand
  the contribution of Road transport to total HM
  emissions.

19
Outlook

• Through identification of major sources and
  uncertainties for a particular metal or source
  hypothesises can be formulated
• These can be verified (e.g. Cu from brake wear)
  or falsified (e.g., Pb from unleaded petrol)
• This is progress! Accuracy increases, uncertainty
  reduces.
• Information from emission inventories and model
  results (regional under- / overestimation) to
  define the candidates for further
  investigation.
• Ex. 1 - metal contents of representative lube
  oils used in Europe, lube oil losses during
  driving and fraction of the lost lube oil burned
  would be a next step in dissecting the exhaust
  metal emissions and tracing the origin of
  measured metals in exhaust PM.
• Ex. 2 Diffuse industrial emissions?
• Difficult to get on the research agenda.. ?
• (Yes, we always complain a bit..)

20
Thank you for your attention

• Acknowledgements
• The project Metal contents of fuels sold on the
  European market was funded by CONCAWE.
• Contact hugo.deniervandergon_at_tno.nl
• jeroen.kuenen_at_tno.nl