Persistent organic pollutants (POPs) such as polycyclic aromatic
hydrocarbons (PAHs) are of great concern due to their persistence,
bioaccumulation and toxic effects.
High temperature processes such as the carbonization of bituminous coal
to form creosote have PAH ratios similar to coal tar or coal combustion
(and generally are indistinguishable from combustion).
PAHs in soils are usually present as complex mixtures that may vary vastly
in the relative abundance of individual components.
High concentrations are often found in areas where coal, coal tar, or heavy
petroleum distillates have been produced or used, e.g. at gas works sites,
metal or bitumen production sites, and wood impregnation sites where
creosote has been used.
Many of these sites are situated in populated areas and future use of the
land for housing and offices may require site remediation.
Such
remediation projects may require fast-screening tools to estimate PAH
levels in soil with some accuracy,
which may be complicated by low concentration levels of some PAHs,
especially those that are toxic. Co-extracted compounds (e.g. petroleum
hydrocarbons, asphaltenes, polar PAH degradation products, etc.) may
interfere during subsequent gas chromatographic (GC) analysis, especially
since they may be present at much higher concentrations than the target
PAHs, and are difficult to remove from the PAH fraction, unless
sophisticated clean-up procedures are employed.
Pressurised liquid extraction–comprehensive two-dimensional
gas chromatography for fast-screening of polycyclic
aromatic hydrocarbons in soil
Ruby Onga, Staffan Lundstedt b, Peter Haglund b, Philip Marriott a,∗
a Australian
Centre for Research on Separation Science, RMIT University, GPO Box 2476V, Melbourne 3001, Australia
Journal of Chromatography A, 1019 (2003) 221–232
Pressurized liquid extraction was performed using
an ASE 200 Accelerated Solvent Extraction system
(Dionex, Sunnyvale, CA, USA) equipped with 11 ml
stainless steel extraction cells. Three soil extraction
methods were used.
• Method 1: Extraction cells were lined with filter
paper, packed with NaSO4, followed by 1 g soil,
mixed homogeneously with 5 g of NaSO4, and
topped with NaSO4. ASE was performed using hexane/
acetone (1:1 v/v) as the extracting solvent. All
extractions were performed at 150 ◦C and 14MPa,
using one dynamic (7 min) and two static extractions
(5 min each), a flush volume of 100%, and
purge time of 60 s. The extracts were evaporated to
1ml and underwent open column silica chromatography
clean-up using 8mm i.d. columns filled with
5 g silica. Samples were quantitatively transferred
to the columns using 2 × 1ml solvent and were
eluted with 5ml n-hexane (waste fraction) then
15 ml n-hexane:dichloromethane (3:1 v/v). Eluate
was carefully evaporated to dryness using N2 blow
down and the residue was reconstituted in 1ml
of toluene. This method employs post-extraction
clean-up.
• Method 2: In-cell cleanup was attempted by packing
the extraction cells as above, but 4 g of silica was
added before the soil/NaSO4 (1:5) mixture. Hexane
was used as the extracting solvent, and the extracts
were then treated as described above but with the
column chromatography step clean-up omitted.
• Method 3: This was performed as Method 2 but using
hexane/dichloromethane (3:1, v/v) as a stronger
extracting solvent.
Method 1 may be classified as an exhaustive
non-selective PLE technique, and the other two methods
as selective PLE techniques with simultaneous
extraction and clean-up.
Creosote
4. Heating and fire safety
Feel a little chilly? Plug into space heater, and wood stove, safely
It happens every winter. The weather turns cold and people turn on the space heater to warm up.
There's always someone who inadvertently starts a fire by putting the heater too close to the
furniture or draperies. Then there are fires caused by the heater being left on all night or tipping
over.
The National Fire Protection Association (NFPA) says heating devices are the leading cause of
fires in the home and a substantial cause of fires in businesses during the cold months. In 2001,
there were 54,900 heating equipment-related home fires in the U.S., 220 civilian deaths, 1,120
civilian injuries and $502 million in direct property damage. All kinds of space heating equipment
is involved in these fires: portable electric heaters, wood stoves, fireplaces, portable kerosene
heaters and room gas heaters.
In Ontario there have been a number of heating-related fires in the past year. Property damage
was substantial, but these fires don't have to happen. Most fires with space heaters are
preventable if key safety measures are followed. To avoid problems, keep space (both portable
and fixed) heaters at least 3 feet away from anything that can burn, including furnishings, bedding
and clothing. Turn the heater off when you leave the room or, in residences, go to sleep.
Wood stoves and fireplaces also need special care. If you're buying a new unit, make sure a
qualified "solid fuel" technician does the installation. If the appliance has already been installed,
have it checked to make sure the installation was done properly.
Most fires in wood stoves, fireplaces, and chimneys occur because of a lack of regular cleaning,
leading to the buildup of creosote, the residue of unburned fuel.
Heating devices should be inspected and cleaned on a regular basis according to the
manufacturer's instructions. Use only seasoned hardwood and don't burn trash in a fireplace
because the fire could burn out of control. Keep sparks and embers inside the fireplace with fire
screens made of heat-tempered glass or sturdy metal.
Heating equipment that burns fuel is a potential source of carbon monoxide (CO). CO is an
odorless, colorless, poisonous gas that is created when fuel burns incompletely. Install CO
alarms in your home to provide you with an early warning if CO is accumulating.
So when the temperature drops, go ahead and use your heating appliances. We want you to be
warm and cozy. But we also want to make sure you're safe.
"Team Up for Fire Safety"
Determination of hydrocarbons in old creosote
contaminated soil using headspace solid phase
microextraction and GC–MS
Mikael Eriksson*, a, Jenny Fäldtb, Gunnel Dalhammara and A.K. Borg-Karlsonb
a
Department of Biotechnology, Group of Microbiology, Royal Institute of Technology,
Stockholm, Sweden
b
Department of Chemistry, Group of Ecological Chemistry, Royal Institute of
Technology, Stockholm, Sweden
Phase association of polycyclic aromatic hydrocarbons
in the Minjiang River Estuary, China
Z. L. Zhang a, b, H. S. Hong b, J. L. Zhou
,
,c
and G. Yu a
a
Department of Environmental Science and Engineering, POPs Research Centre,
Tsinghua University, Beijing 100084, PR China
b
Key Laboratory of Marine Environmental Science of Ministry of Education,
Environmental Science Research Centre, Xiamen University, Xiamen 361005, PR China
c
Department of Biology and Environmental Science, School of Life Sciences, University
of Sussex, Falmer, Brighton BN1 9QJ, UK
Science of The Total Environment
Volume 323, Issues 1-3 , 5 May 2004, 71-86
In this work the levels of 16 priority PAHs were determined in water, pore water,
sediment, soil and vegetable samples from Minjiang River Estuary, China. Total PAH
concentrations varied from 9.9 to 474 g/l in water, 82.1 to 239 g/l in pore water, 112 to
877 ng/g dry wt. in surficial sediments, 128 to 465 ng/g dry wt. in soil and 8600 to
111 000 ng/g dry wt. in Chinese vegetables. Overall, the mean concentrations of PAHs
were present in higher levels in pore water than that in surface water, due possibly to
higher concentrations of dissolved organic carbon or colloids with which the hydrophobic
pollutants were strongly associated. Such a concentration gradient implies a potential flux
of pollutants from sediment pore water to overlying water. Contamination was dominated
by high molecular mass PAH compounds in all samples, indicating combustion-derived
sources (for example, pyrolysis at high temperature). The levels of PAHs in water and
vegetable were relatively high in comparison to other studies, although PAHs in sediment
and soil were comparable to those found in many other similar environments. The ratios
of selected PAHs indicated again that PAHs in Minjiang River Estuary were mainly
derived from incomplete combustion of fossil fuel.
Sediment, soil and vegetable samples were
extracted by ultrasonication, a method developed
and verified by the authors (Hong et al., 1995;
Zhou et al., 2000; Maskaoui et al., 2002).Briefly ,
sediment and soil samples were homogenised,
while plant samples were cut into small pieces.
Sub-samples (f100 g wet wt.) were mixed with
copper powder, anhydrous Na SO , IS (500 ng) 2 4
and 60 ml of hexane:dichloromethane (1:1), which
were extracted for 30 min and then overnight.The
extracts were concentrated to 0.5 ml by rotaryevaporation
and under a gentle stream of nitrogen.
The concentrated extracts were fractionated by a
silica gelyalumina column (4 mm i.d.=90 mm).
The column was then eluted first with 3.5 ml of
hexane and the solution discarded.Further elution
was by a mixture of hexane:dichloromethane (1:1)
to obtain PAHs (Hong et al., 1995; Zhou et al.,
2000; Maskaoui et al., 2002).All the extracts were
concentrated by gentle N blow-down to approxi- 2
mately 100 ml.In order to minimise losses of
more volatile PAHs, it is essential not to completely
dry the extracts.
Predicting the efficacy of polycyclic aromatic hydrocarbon
bioremediation in creosote-contaminated soil using bioavailability
assays
JUHASZ Albert L.; WALLER Natasha; STEWART Richard;
CAT.INIST.FR
http://cat.inist.fr/?aModele=afficheN&cpsidt=17248224
2005, vol. 9, no2, pp. 99-114.
Nonexhaustive extraction (propanol, butanol, hydroxypropylβ-cyclodextrin
[HPCD]), persulfate oxidation and biodegradability assays were employed
to determine the bioavailability of polycyclic aromatic hydrocarbons (PAHs)
in creosote-contaminated soil. After 16 weeks incubation, greater than 89%
of three-ring compounds (acenaphthene, anthracene, fluorene, and
phenanthrene) and 21% to 79% of four-ring compounds (benz[a]anthracene,
chrysene, fluoranthene, and pyrene) were degraded by the indigenous
microorganisms under biopile conditions. No significant decrease in five(benzo[a]pyrene, benzo[b+k]fluoranthene) and six-ring compounds
(bend[g,h,i]perylene, indeno[1,2,3-c,d]pyrene) was observed. Desorption of
PAHs using propanol or butanol could not predict PAH biodegradability:
low-molecular-weight PAH biodegradability was underestimated whereas
high-molecular-weight PAH biodegradability was overestimated. Persulfate
oxidation and HPCD extraction of creosote-contaminated soil was able to
predict three- and four-ring PAH biodegradability; however, the
biodegradability of five-ring PAHs was overestimated. These results
demonstrate that persulfate oxidation and HPCD extraction are good
predictors of PAH biodegradability for compounds with octanol-water
partitioning coefficients of <6.