CO2_2016 - page 21

19
Chimica Oggi - Chemistry Today
- vol. 34(2) March/April 2016
RESULTS AND DISCUSSION
The data in Primary
characterization of
samples of the collected
sediment are described
in Table 3.
Levels above 100 μS.cm
-1
conductivity in the water
indicate that it has
impacted environments
(18) in the areas of points
6 and 7, it shows higher
values - indicating a high
load of contaminants
transported at this point
which is confirmed by
the values of TPH and
aliphatic. The study had
values greater than 100
µS.cm
-1
, confirming that
these points received the
contaminated discharge
from stormwater runoff
channels and other
values demonstrated the
effect of dilution of that
burden within the São
Gonçalo channel.
Total amounts of
petroleum hydrocarbons
(TPH) above 3 x 10
5
μg.kg
-1
for TPH and
greater than 5 x 10
5
μg. kg
-1
to aliphatic in
rainwater runoff channels
indicates that the
sediment are polluted
by hydrocarbons (19).
Thus we can see the
point 01 does not receive
effluent, it has the lowest
value of TPH, having its
area considered without
impact. The other points
have high TPH values, proving the receipt of hydrocarbon
charges brought by the runoff of rainwater, stressing the
point 06 showed very high value, this is the point that
drains most welcome part of urban transport and shops
next to it has the point 07 also has considerable value
but does not exhibit hydrodynamic conditions for the
accumulation of contaminants evidenced by the large
grain size and low levels of total organic matter.
Smaller particles provide adsorption, accumulation and
persistence of hydrocarbons in the sediment (20). We
can see that point 06 has the largest amount of particles
<63 μm, we can relate the value found for the amount of
moisture tone is obtained at the same point. The point 04
also showed favorable grain size accumulation.
The Table 5 shows the figures of merit for the method used
for analysis of PAHs. The system behaved in a linear fashion
over a concentration range of 20-200 mg.L
–1
for the 16
PAHs studied. In all situations, the correlation coefficient
this study and an aliquot
of 1 μl of each extract was
injected into the GC-MS in
split less mode.
The hydrocarbons were
quantified using a GC-
MS (Shimadzu ultra-QP
2010), column RTX 5MS
(30 m comp. x 0.25 mm ø
x 0.25 μm film thickness).
Injector and interface were
maintained at 280 °C and
the ion source at 200 °C.
The calibration curve for
the 16 PAHs, covered a
range between 20.0 and
200.0 μg.l
-1
, comprising five
different points. Each point
represents the average
of three independent
measurements of the area.
Oven temperature program
used in SIM mode was: initial
temperature 80 ºC, 5 min
on hold being heated up to
160 ºC at 8 ºC min-1201, and
then heated up to 300 ºC at
3 ºC min-1 202 (15 min hold).
The oven temperature
program used in
either SIM will be
optimized seeking maximum
resolution and
shorter analysis.
The ions will be monitored
(m/z) 128, 152, 154, 166,
178, 202, 228, 252, 276,
278). The deuterated PAHs
were analyzed in the same
conditions. The calibration
curve ranges from 1 to 10.0
mg.l
-1
SIM mode (m/z)
for Phenanthrene D10 188
and 240 to 264; Chrysene
D12; Perylene D12. The
ionization energy was 70
eV. The carrier gas was helium (99.999%) at a constant
flow rate 1.0 ml.min
-1
. The limit of detection (LOD) was
calculated using the sum of the average of the blank
signal and three times its standard deviation, while the
limit of quantification (LOQ) was calculated by summing
of the blank signal with ten times its standard deviation.
The precision of the chromatographic method was
developed by repeating 11 times the pattern analysis 75
µg.L
-1
.
The evaluation of the contamination was compared
with the limits established by the Canadian Council of
Ministers of the Environment, which defines the limits TEL
(Threshold Effect Level) and PEL (Probable Effect Level)
that define the sediment ability to cause or to have no
adverse effects on organisms (16) water and the possibility
of dredging without causing damage to the environment
- the limits set out in CONAMA Resolution No. 344/2004 of
Brazil (17).
Table 3.
Preliminary characterization of sediments and water:
Table 4.
Figures of merit for the analytical procedure GC-MS for HPAs:
m/a –ratio mass load of the monitored ions. y= ax +b (a – slope; b linear
coefficient; R
2
– coefficient linear correlation; LOD – detection limit; LOQ –
quantification limit in µg.kg
–1
.
1...,11,12,13,14,15,16,17,18,19,20 22,23,24,25,26,27,28,29,30,31,...68
Powered by FlippingBook