Environmental Engineering Reference
In-Depth Information
Analysis
For determination of total mass concentration, the filters were weighted using
a microbalance (Sartorius SE 2-F, readability = 0.1 mg) before and after sampling.
In each case the mean value of five weightings was used for calculation. The standard
deviation was kept smaller than 0.1 (in most cases £0.05). Additionally, the weighing
was controlled by blank filters.
Water-soluble ions were analyzed by ion chromatography (IC). For this analysis,
one quarter of each of the collected filters was shaken for 45 min in 15 mL ultrapure
deionized water (Milli-Q) and additionally extracted ultrasonically for 30 min in
order to release the water-soluble parts.
For anions, a Dionex ICS-1000 with ASRS-ULTRA suppressor, Ion Pac AS4A-SC
column and a Na
2
CO
3
/NaHCO
3
-eluent was used. Cations were analyzed with a Dionex
DX-120 with CSRS-ULTRA suppressor, Ion Pac CS12, using a 0.1 M H
2
SO
4
-eluent.
Standard solutions of both anions (Multi ion anion IC standard solution Specpure,
Alfa-Aesar) and cations (Multi-component Cation Mix 2, Acculon) were used in dif-
ferent concentrations for quality control.
Results and Discussion
Particle Mass Concentration
In 2006 the average total mass concentration for PM
2.5
samples from all five sampling
sites was 90.7 ± 57.3 µg/m
3
for day samples and 91.6 ± 67.9 µg/m
3
for night samples
(all mean values in this paper are expressed plus/minus standard deviation). Site 4
showed highest annual PM
2.5
concentrations with 114.7 ± 79.1 µg/m
3
(average for day
and night). The average TSP concentration (sampled only at site 4) was 371.4 ± 141.9
µg/m
3
in 2006. These values exceed even the Chinese class III standard for annual
TSP concentrations. China has three classes for air quality standards which are the
following for TSP: class I - 60 µg/m
3
, class II - 120 µg/m
3
, class III - 150 µg/m
3
. No
threshold value exists for PM
2.5
in China until now. The yearly average PM
2.5
concen-
trations for all five sites are shown in Fig.
2
.
The mass concentration varied considerably over the course of the year. Highest
concentrations, both in PM
2.5
and TSP, were found in winter with 113 ± 72 and 448 ±
165 µg/m
3
, respectively. Summer values showed lowest particle concentrations; 72
±44 and 235 ± 60 µg/m
3
, respectively. Spring and autumn concentrations were also
quite high (spring: 94.3 ± 53.8 and 405.3 ± 126.3 µg/m
3
, autumn: 76.3 ± 38.4 and
396.5 ± 103.0 µg/m
3
).
In this study, the seasons were defined as follows: winter - Dec, Jan, Feb, spring -
Mar, Apr, May, summer - June, July, Aug, autumn - Sept, Oct, Nov.
