Validation and application of a thermal-optical reflectance (TOR) method for measuring black carbon in loess sediments

In an effort to assess the potential contamination and determine the environmental risks associated with heavy metals, the surface sediments in Liaodong Bay, northeast China, were systematically sampled and analyzed for the concentrations of Cu, Pb, Zn, Cr, Ni, As, and Hg. The metal enrichment factor (EF) and geoaccumulation index (I (geo)) were calculated to assess the anthropogenic contamination in the region. Results showed that heavy metal concentrations in the sediments generally met the criteria of China Marine Sediment Quality (GB18668-2002); however, both EF and I (geo) values suggested the elevation of Pb concentration in the region. Based on the effect-range classification (TEL-PEL SQGs), Cu, Pb, Ni, and As were likely to pose environment risks, and the toxic units decreased in the order: Ni &gt; Pb &gt; Cr &gt; Zn &gt; As &gt; Cu &gt; Hg. The spatial distribution of ecotoxicological index (mean-ERM-quotient) suggested that most of the surface sediments were &quot;low-medium&quot; priority zone. Multivariate analysis indicated that the sources of Cr, Ni, Zn, Cu, and Hg resulted primarily from parent rocks, and Pb or As were mainly attributed to anthropogenic sources. The results of this study would provide a useful aid for sustainable marine management in the region.</p

Light attenuation cross-section of black carbon in an urbanatmosphere in northern China

Fine particulate matter (PM2.5) samples were collected over two years in Xi&rsquo;an, China to investigate the relationships between the aerosol composition and the light absorption efficiency of black carbon (BC). Real-time light attenuation of BC at 880&nbsp;nm was measured with an aethalometer. The mass concentrations and elemental carbon (EC) contents of PM2.5 were obtained, and light attenuation cross-sections (&sigma;ATN) of PM2.5 BC were derived. The mass of EC contributed &sim;5% to PM2.5 on average. BC &sigma;ATN exhibited pronounced seasonal variability with values averaging 18.6, 24.2, 16.4, and 26.0&nbsp;m2/g for the spring, summer, autumn, and winter, respectively, while averaging 23.0&nbsp;m2/g overall. &sigma;ATN varied inversely with the ratios of EC/PM2.5, EC/[SO42&minus;], and EC/[NO3&minus;]. This study of the variability in &sigma;ATN illustrates the complexity of the interactions among the aerosol constituents in northern China and documents certain effects of the high EC, dust, sulfate and nitrate loadings on light attenuation.</p

Spatial distributions and sequestrations of organic carbon and black carbon in soils from the Chinese loess plateau

Concentrations of soil organic carbon (SOC), black carbon (BC), char, and soot in topsoils (0-20 cm) and vertical soil profiles (0-100 cm) from the Chinese Loess Plateau (CLP) were investigated. Objectives of the study were to establish the spatial distributions and estimate the sequestrations of these substances. The SOC, BC, char and soot concentrations were higher in the eastern and southeastern parts of the plateau and lower in the north, which is consistent with the patterns of economic development and energy consumption. The highest average SOC concentration was found in the clayey loess zone, followed by the loess and sandy loess zones. Similar trends were observed for BC, char and soot, suggesting interactions with clay and silt are potentially important influences on DC and BC. The SOC contents in topsoils varied from 0.31 to 51.81 g kg(-1), with a mean value of 6.54 g kg(-1), while BC and char concentrations were 0.02 to 5.5 g kg(-1) and 0.003 to 4.19 g kg(-1), respectively, and soot ranged from 0.01 to 132 g kg(-1). Unlike SOC, both BC and char decreased with soil depth, whereas soot showed little variation with depth. BC and char were correlated in the topsoils, and both correlated moderately well with SOC (R-2=0.60) and soot (R-2= 0.53). The SOC pools sequestered in the 0 to 20 cm and 0 to 100 cm depths were estimated to be 0.741 and 3.63 Pg, respectively, and the BC pools sequestered in the 0 to 20 cm and 0 to 100 cm depths were 0.073 and 0.456 Pg, respectively. Therefore the quantity of carbon stored in the sediments of the CLP evidently exceeds 10(9) tons. The char contained in the upper 20 cm layer was 0.053 Pg, which amounted to 72.5% of the BC in that layer.</p

Seasonal variation and health risk assessment of atmosphericPM2.5-bound polycyclic aromatic hydrocarbons in a classicagglomeration industrial city, central China

Sixty atmospheric sample concentrations of PM2.5 and polycyclic aromatic hydrocarbons (PAHs) in PM2.5 were analyzed in distinct seasonal variations from a classic agglomeration industrial city. The concentrations of PM2.5 ranged from 6.96 to 260.06&nbsp;&mu;g/m3 with an average of 177.05&nbsp;&mu;g/m3. Only 38% of the sampling days were superior to the 24-h limit value (75&nbsp;&mu;g/m3) of ambient air quality standards (AAQs), and the samples from autumn and winter exceeded the limit value. The total PAHs ranged from 1.51 to 44.51&nbsp;ng/m3 with an average of 10.65&nbsp;ng/m3. The highest and lowest concentrations of total PAHs appeared in winter and summer with averages of 22.56 and 4.03&nbsp;ng/m3, respectively. Correlation analysis revealed that high-molecular-weight PAHs (HMW-PAHs) (4-, 5-, 6-ring PAHs) were significantly and negatively correlated with temperature and water-soluble total organic carbon (WTOC), and significantly correlated with water-soluble total nitrogen (WTN). The 4-, 5- and 6-ring PAHs were dominant, especially those of 4-ring PAHs, which were above 30% of the total PAHs in each season. Source apportionment indicated that PM2.5-bound PAHs in Huangshi were mainly derived from pyrogenic source, vehicle exhaust, coal combustion, and biomass burning. Incremental lifetime cancer risks (ILCRs) showed no potential carcinogenic risk from the PM2.5-bound BaP-eq. ILCRs in winter were the highest, and the risks for adults were approximately an order of magnitude higher than those for children

Sources and Formation Processes of Short-Chain Saturated Diacids (C2–C4) in Inhalable Particles (PM10) from Huangshi City, Central China

PM10 samples were collected from Huangshi (HS) city, Central China during April 2012 to March 2013, and were analyzed for short-chain saturated dicarboxylic acids (diacids) using a capillary gas chromatograph (GC). We found that oxalic acid (C2, 318 ± 104 ng·m−3) was the most abundant diacid species, followed by malonic acid (C3, 25.4 ± 9.11 ng·m−3) and succinic acid (C4, 2.09 ± 0.52 ng·m−3). The concentrations of C2 and C4 diacids were highest in winter, followed by summer and spring, and lowest in autumn. C3 diacid was decreased in the order of summer &gt; winter &gt; autumn &gt; spring. Further, the seasonal variations of WSOC (water-soluble organic carbon)- and OC (organic carbon)-normalized diacid concentrations were similar to those of diacid concentrations, suggesting that both primary emission and secondary production are important sources for diacids in Huangshi (HS) aerosols. Strong correlations were found among C2 diacid and the three ions SO42−, NO3−, and NH4+ in summer and winter, suggesting that the species could undergo a similar secondary oxidation processing. C2 had good correlation with K+ in summer and autumn, which indicates an enhanced contribution of combustion sources for C2 diacid. Moreover, according to the ratio of C2/K+, we can conclude that C2 diacid should be formed by a secondary reaction of biomass combustion in HS aerosols, especially in summer and autumn. The ratios of C2/C4 and C3/C4 were compared with those reported in other sites, and the results suggest that HS aerosols should be more photochemically aged than at other urban areas. Principal component analysis of diacids and selected water-soluble inorganic ions over four seasons suggests that HS aerosols are influenced not only from primary emission, but also from secondary reaction. According to the linear relation between C2 and C3 diacids, the results indicate that C2 diacid is formed from the oxidation of hydrocarbon compounds in spring, while it is from the oxidation of C3 and C4 diacids in summer, autumn, and winter

Characterization of Polycyclic Aromatic Hydrocarbons (PAHs), Iron and BlackCarbon within Street Dust from a Steel Industrial City, Central China

Twenty-two street dust samples collected from a small steel city, central China, were analyzed for 16 USEPA priority PAHs to investigate the concentration, spatial distribution relationship with black carbon (BC) and Iron (Fe), and the source apportionment and to assess the health risk of these compounds. The mean contents of PAHs, BC and Fe were 4.43 &micro;g g&ndash;1, 12837.97 mg kg&ndash;1, 70205.70 mg kg&ndash;1, respectively. The highest spot was in the surrounding of the E&rsquo;zhou Steel Plant and the Steel Rolling Mill of E&rsquo;zhou. The correlation analysis indicated that there was no obvious relationship between Fe with each other, the PAHs significantly correlated to black carbon (BC), which might be caused by the continuous emission sources of iron and steel production. The results of sources identification suggested that PAHs contaminations in street dust were a mixed source of industrial production and traffic emission combustion. The incremental lifetime and cancer risks (ILCRs) of exposing to PAHs in the street dust of the E&rsquo;zhou city for the three age groups (namely childhood, adolescence, adulthood) fluctuated with in the range of 10&ndash;6 to 10&ndash;4, indicating a potential of carcinogenic risk for exposed populations.</p

Characteristics and Sources of Black Carbon in Atmospheric Dustfall Particlesfrom Huangshi, China

Concentrations of carbonaceous particles in atmospheric dustfall particles in Huangshi, an industrial city in central China, were determined using a thermal-optical reflectance method. The black carbon (BC) contents in ninety-five dustfall samples ranged from 4.3 to 64.9 g kg⁻&sup1; with an average of 17.0 g kg⁻&sup1;. These values were higher than those in world background soils and demonstrated serious contamination of the environment in this city. Overall, BC accounted for 17.6-71.3% (mean: 42.0%) of the organic carbon (OC), and BC and OC were positively correlated (r&sup2; = 0.90). Average char and soot contents were 8.01 g kg-1 and 8.65 g kg⁻&sup1;, respectively, and char/soot ratios ranged from 0.28 to 1.97 with an average of 1.01. All the measured carbonaceous species positively correlated with each another, suggesting their common sources. BC, char, and soot showed large spatial distribution variability, with high levels of BC adjacent to the presumed emission sources, such as a power plant and railway line. Analyses of BC/OC and char/soot ratios indicate major impacts from fossil fuel combustion, especially motor vehicle emissions and coal combustion. Industrial dusts related to coal use appear to be the major contributor to BC in dustfall, and this is likely related to the extensive industrial activities in the city, including metal smelting.</p

Impact of Meteorological Parameters and Gaseous Pollutants on PM2.5 and PM10Mass Concentrations during 2010 in Xi’an, China

Mass concentrations of PM2.5 and PM10 from the six urban/rural sampling sites of Xi&rsquo;an were obtained during two weeks of every month corresponding to January, April, July and October during 2010, together with the six meteorological parameters and the data of two precursors. The result showed that the average annual mass concentrations of PM2.5 and PM10 were 140.9 &plusmn; 108.9 &micro;g m&ndash;3 and 257.8 &plusmn; 194.7 &micro;g m&ndash;3, respectively. Basin terrain constrains the diffusion of PM2.5 and PM10 concentration spatially. High concentrations in wintertime and low concentrations in summertime are due to seasonal variations of meteorological parameters and cyclic changes of precursors (SO2 and NO2). Stepwise Multiple Linear Regression (MLR) analysis indicates that relative humidity is the main factor influencing on meteorological parameter. Entry MLR analysis suggests that SO2 from local coal-burning power plants is still the primary pollutant. Trajectory cluster results of PM2.5 at BRR indicate that the entrained urban pollutants carried by the westerly or winter monsoon forms the dominant regional pollution sources in winter and spring. Ultraviolet (UV) aerosol index verified the source and pathway of dust storm in spring.</p