Black carbon in soils from different land use areas of Shanghai,China: Level,sources and relationship with polycyclic aromatic hydrocarbons

Black carbon (BC) in soils plays a key role of carrying hydrophobic pollutants like polycyclic aromatic hydrocarbons (PAHs). However, little is known about the spatial distribution, sources of BC and its relationship with PAHs in urban soils. We studied BC, total organic carbon (TOC) and PAHs concurrently in 77 soils collected from downtown area, suburban and rural area and industrial area of Shanghai, China. BC was determined by both chemical oxidation (dichromate oxidation, BC_Cr) and chemo-thermal oxidation (CTO-375, BC_CTO). BC sources were identified qualitatively by BC/TOC concentration ratios and BC-cogenerated high molecular weight (HMW) PAH isomer ratios and quantitatively by principal component analysis followed by multiple linear regression (PCA-MLR). Results showed that BC_Cr concentration (4.65 g/kg on average) was significantly higher than BC_CTO (1.91 g/kg on average) in Shanghai soils. BC_Cr concentrations in industrial area were significantly higher than those in other two. Stronger correlation was found between PAHs and TOC, BC_Cr than that between PAHs and BC_CTO, which indicates the possibility of PAHs being carried by charcoal and other organic matters thus negating its exclusive dependence on soot. Charcoal was therefore suggested to be taken into account in studies of BC and its sorption of PAHs. BC/TOC ratios showed a mixed source of biomass burning and fossil fuel combustion. PCA scores of BC-cogenerated HMW PAHs isomer ratios in potential sources and soil samples clearly demonstrated that sources of BC in urban soils may fall into two categories: coal and biomass combustion, and traffic (oil combustion and tire wear). PCA-MLR of HMW PAHs concentrations in soil samples indicated that coal and oil combustion had the largest contribution to BC in urban soils while tire wear and biomass combustion were important in downtown and rural area, respectively, which indicated they were main sources of HMW PAHs and presumably of BC.     

Polycyclic aromatic hydrocarbons in surface sediments of Laizhou Bay,Bohai Sea,China

Concentration, distribution, and sources of 16 polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments of Laizhou Bay, China. Total PAH concentrations ranged from 97.2 to 204.8 ng/g, with a mean of 148.4 ng/g. High concentrations of PAHs were found in the fine-grained sediments on both sides of the Yellow River estuary (YRE). In contrast, low levels of PAHs were observed in relatively coarse grain sediments, suggesting hydrodynamics influence the accumulation of sedimentary PAHs. The YRE and its adjacent area is the main sink for Yellow River-derived PAHs. Both PAH isomer ratios and principal component analysis (PCA) with multivariate linear regression (MLR) were applied to apportion sources of PAHs. Results indicated that both pyrogenic and petrogenic PAH sources were important. Further PCA/MLR analysis showed that the contributions of coal combustion, petroleum combustion and a combined source of spilled oil and biomass burning were 41, 15 and 44%, respectively. From an ecotoxicological viewpoint, the studied area appears to have low levels of PAH pollution.     

Characterization and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments in the Yellow River Estuary, China

Concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments of the Yellow River Estuary (YRE). The isobath-parallel tidal and residual currents play important roles in the variation of PAH distribution, such that the contamination level of PAHs in fine-grained sediments is significantly higher than in the relatively coarse grain size sediments. Both diagnostic ratios and principal component analysis (PCA) with multivariate linear regression (MLR) were used to apportion sources of PAHs. The results revealed that pyrogenic sources are important sources of PAHs. Further analysis indicated that the contributions of coal combustion, traffic-related pollution and mixed sources (spills of oil products and vegetation combustion) were 35, 29 and 36 %, respectively, using PCA/MLR. Pyrogenic sources (coal combustion and traffic-related pollution) contribute 64 % of anthropogenic PAHs in sediments, which indicates that energy consumption could be a predominant factor in PAH pollution of YRE. Acenaphthylene and acenaphthene are the two main species of PAHs with more ecotoxicological concern in YRE.     

Application of spatial analysis and multivariate analysis techniques in distribution and source study of polycyclic aromatic hydrocarbons in the topsoil of Beijing,China

Surface soil samples were collected from 161 sites throughout the downtown and suburban area of Beijing, China. The samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) concentrations. Through Kriging analysis, five heavily contaminated zones were identified in the study area. Sources of PAHs in the soil were apportioned using principal factor analysis and multiple linear regression. Three factors were identified representing coal combustion/vehicle emission, coking emission, and petroleum sources, respectively. The relative contributions of the three sources were 48% for coal/vehicle emission, 28% for coking emission, and 24% for petroleum sources. The contributions of total PAHs from the three sources were 16.4, 4.63 and 3.70 ng g⁻¹, respectively. Spatial analysis indicated that the contribution of coal/vehicle sources was higher in the downtown area than in the suburban area, the petroleum sources had a high contribution in the urban area, and the contribution of coking sources was high in the suburban area. The results indicated that PAH contamination in the surface soil in Beijing was closely related to the spatial characteristics of energy consumption and functional zoning. Improvement of the energy consumption structure and relocation of industries with heavy pollution are effective ways to control PAH contamination in surface soil in the area.     

Source apportionment of elevated PAH concentrations in sediments near deep marine outfalls in Esquimalt and Victoria,BC, Canada: Is coal from an 1891 shipwreck the source?

Previous studies have suggested that coal from the 1891 shipwreck of a collier off Victoria, BC, Canada is responsible for elevated parent (unsubstituted) PAH concentrations in sediments near deep marine outfalls from Esquimalt and Victoria in the Strait of Juan de Fuca. To resolve this question, we analysed a comprehensive suite of resolved and unresolved complex mixture (UCM) alkanes, tricyclic terpane, hopane and sterane biomarkers, and parent and alkyl polycyclic aromatic hydrocarbons (PAHs) in samples of coal, wastewater and sediments. Composition patterns, principal components analysis (PCA) models and PAH and biomarker ratios all indicate that coal from the collier does not make a dominant contribution to any sediment sample. Mass balance calculations based on the n-C₂₄ content and 24/4 tetracyclic terpane to 26/3R tricyclic terpane ratio in coal provide a particularly good match between predicted and observed alkyl PAH concentrations for sediments with high alkyl naphthalenes and phenanthrene/anthracenes and low UCM, but the predicted coal contribution substantially underestimates the measured parent PAHs for all sediment samples. Methylbenz[a]anthracene/chrysene profiles for sediments with a dominance of parent PAHs are very close to coal tar, with a marked predominance of methylbenz[a]anthracenes and the possible 10-methylbenz[a]anthracene as a major constituent, while the methylchrysenes predominate in coal. Hence, coal from the collier could account for most alkyl PAHs in the sediments, but dredged sediment containing pyrolised coal waste from a former coal gas plant in Victoria Harbour is a more likely source for the samples with elevated parent PAHs. PAH ratios indicate that these sources are superimposed on combustion PAHs introduced by a combination of atmospheric deposition and delivery via stormwater and the outfalls. Parent PAH distributions also suggest that PAHs in wastewater that originate from oils and soot in liquid fossil fuel combustion are dispersed and degraded, while the larger wood char particles (containing PAHs more protected from degradation) settle closer to the outfalls. Overall, results suggest that PAHs have predominant sources in wood combustion, coal and possibly coke, with a likelihood of much lower bioavailability than would be expected from wastewater dominated by oils and soot from vehicle combustion.     

西南背景区冬、夏季黑碳稳定碳同位素组成及来源

为确定中国西南背景区不同季节细颗粒物中黑碳的浓度水平和来源特征,分别于2018年冬季(1月)和夏季(7月)在贵州普定喀斯特生态系统观测研究站采集细颗粒物样品,测定其水溶性离子成分、黑碳浓度及稳定碳同位素组成(δ13CBC),结合贝叶斯模型探讨黑碳来源贡献.结果表明,采样期间黑碳冬季平均浓度为(1.2±0.6)μg/m3...     

Application of multivariate spatial analysis in scale-based distribution and source study of PAHs in the topsoil: an example from Tianjin,China

Polycyclic aromatic hydrocarbons (PAHs) in soil originate from various sources under different spatial scales. Coregionalization analysis is more revealing than univariate geostatistical analysis. Scale-dependent spatial features of variables reflect different sources of spatial variability. In this study, 188 topsoil samples in the Tianjin area were collected. The contents of 16 PAHs and soil background properties were determined for all samples. A multivariate geostatistical approach was used for multi-scale spatial analysis for PAH compounds. Results show that coal combustion was the major source for the spatial distribution patterns of PAHs in the topsoil of the studied area. It worked mainly at the short-range scale (5–10 km). Significant spatial variation patterns were identified. In contrast, no significant spatial distribution trends at the nugget (0–5 km) or long-range scales (10–50 km) were seen. Long-range transport and site contamination of PAHs might not be key contributors in forming the distribution pattern of PAHs in the topsoil of Tianjin area.     

用扫描电镜技术识别广州市大气颗粒物主要种类

利用扫描电镜技术对大气颗粒物的来源进行识别，采取手动分析与自动分析两种方法，得出的结果在总趋势上相互一致。手动方法和自动方法各有特点。自动分析在细颗粒，特别是含硫颗粒分析方面有优势，而手动分析在形貌观测和确定有机粗颗粒污染状况方面有独到之处。实验结果表明，大气颗粒物的来源是多样的，治理措施也应是综合性的，既要注意工业点源的污染治理和排放控制，如燃煤飞灰，钙质颗粒富铁颗粒等，也要注意面源排放，如土壤扬尘和碳质颗粒，碳质颗粒的来源复杂，可以是工业过程，燃烧过程，机动车尾气，生物质燃，树木自然排放。     

Risk assessment of polycyclic aromatic hydrocarbons in the West Port semi-enclosed basin (Malaysia)

Sediment samples collected from the West Port, the west coastal waters of Malaysia, were analyzed by standard methods to determine the degree of hydrocarbon contamination and identify the sources of polyaromatic hydrocarbons (PAHs). Concentrations of PAHs in the port sediments ranged from 100.3 to 3,446.9 μg/kg dw. The highest concentrations were observed in stations close to the coastline, locations affected by intensive shipping activities and industrial input. These were dominated by high-molecular-weight PAHs (4–6 rings). Source identification showed that PAHs originated mostly pyrogenically, from the combustion of fossil fuels, grass, wood, and coal or from petroleum combustion. Regarding ecological risk estimation, only station 7 was moderately polluted, the rest of the stations suffered rare or slight adverse biological effects with PAH exposure in surface sediment, suggesting that PAHs are not considered as contaminants of concern in the West Port.     

Polycyclic aromatic hydrocarbon concentrations in urban soils representing different land use categories in Shanghai

An extensive soil survey was carried out in Shanghai to investigate the spatial distribution and possible sources of polycyclic aromatic hydrocarbons (PAHs) in urban soils. Soil samples were collected from highways, iron-smelting plants, steel-smelting plants, shipbuilding yards, coking plants, power plants, chemical plants, urban parks, university campuses and residential areas and were analyzed for 16 PAHs by gas chromatography with mass detection. High PAH concentrations were found in all locations investigated, with mean values of soil total PAH concentrations in the range 3,279–38,868 μg/kg DM, and the PAH concentrations were significantly influenced by soil organic matter content. Soil PAH profiles in all districts were dominated by PAHs with 4–6 rings. Principal components analysis and diagnostic ratios of PAHs indicate that they were mainly derived from coal combustion and petroleum but in soils from highways the PAHs were derived largely from vehicle exhaust emissions. The high concentrations of PAHs found indicate that many urban soils in Shanghai represent a potential hazard to public health.     

Factors affecting pore water hydrocarbon concentrations in Puget Sound sediments

Polycyclic aromatic hydrocarbon (PAH) and aliphatic hydrocarbon concentrations have been determined for sediments and associated pore waters collected at 2 sites (11 stations) in Puget Sound, Washington (northwest U.S.A.). These sediments have been contaminated to varying degrees by hydrocarbons from a creosote plant and from various combustion sources. PAH were not detected in pore waters of sediments whose PAH were primarily derived from combustion and natural sources, even though pore water concentrations predicted from sediment concentrations and two-phase equilibrium partitioning models were above detection limits from most PAH. Equilibrium partition coefficients calculated from field aqueous and solid phase data from an area contaminated with creosote agreed with laboratory-derived coefficients to within a factor of ± 4. Pore water concentrations of creosote-derived aliphatic hydrocarbons increase with increasing concentration in bulk sediments. However, pore water concentrations of natural and contaminant aliphatic hydrocarbons are much higher than predicted by solubility data, possibly due to association with nonfilterable dissolved organic matter and colloids. Other major factors controlling hydrocarbon pore water concentrations include differential hydrocarbon sources, specific particle associations and solubility.     

Sources and contamination characteristics of PAHs in environmental media in a karst underground river system (southern China)

The aim of this study was to determine the sources and contamination characteristics of polycyclic aromatic hydrocarbons (PAHs) in various environmental media in a karst underground river system. For this purpose, air, underground river water, sediment, and soil samples were collected from a typical underground river in southern China in the dry and wet seasons of 2013–2014, and the compositional spectra, distribution, and ratio characteristics of 16 PAHs were determined for comparative analysis. The results show that three 2–3-ring PAHs (naphthalene, phenanthrene, and fluoranthene) mainly occur in air and underground river water. In sediments and soils, 4–6-ring PAHs are the main components. The PAH concentrations in the air in the wet season are clearly greater than those in the dry season, while it is the opposite in the underground water. Seasonal differences in the concentration of PAHs in the sediments and soils are minor. The concentrations of PAHs in the environmental media overall showed variation in the following order: upstream < midstream < downstream, and this is related to pollutant discharge, adsorption, etc. The main source of PAHs in the upstream area is the combustion of grass, wood, and coal, while it is petroleum in the midstream area, and combustion of grass, wood, coal, and petroleum near the outlet of the underground river. It is necessary to change the energy structure in the study area, improve the efficiency of environmental protection facilities, reduce the emission in vehicle exhaust, and control pollution by PAHs at their sources.     

Concentrations and possible sources of PAHs in sediments from Bohai Bay and adjacent shelf

Concentrations, spatial distribution and sources of 16 polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency as priority pollutants were investigated in surface sediments of Bohai Bay, North China. Total concentrations of PAHs were in the range of 140.6–300.7 ng/g (dry wt), with an average of 188.0 ng/g. The three predominant PAHs were phenanthrene, acenaphthene and naphthalene. Sedimentary PAH concentrations of the north and central Bohai Bay were higher than those of the southern side of this bay. PAHs source analysis suggested that PAHs in most of the sediments were mainly from grass, wood and coal incomplete combustion. At other stations near the estuaries (Luanhe River Estuary and Chaohe River Estuary) or the oil drilling platform, both petrogenic and pyrogenic inputs were significant. The pyrogenic PAHs close to the oil drilling platform were mainly from petroleum combustion.     

Alkane and PAH biomarkers as tracers of terrigenous organic carbon in Arctic Ocean sediments

We present the first sedimentary biomarker study encompassing the entire Arctic Ocean. A large data set of organic markers for terrigenous, petroleum and combustion inputs [alkanes, hopanes and steranes, parent and alkyl polycyclic aromatic hydrocarbons (PAHs)] is examined for patterns in space and time using principal components analysis (PCA) and partial least squares (PLS). Biomarker patterns reveal the central Arctic Ocean basin sediments to be compositionally distinct from those of the Mackenzie River/Beaufort Sea and Barents Sea, but similar to those of the Laptev Sea. PAH distributions reflected in PAH ratios and PCA projections demonstrate that Arctic Ocean sediment is dominated by natural inputs to the extent that anthropogenic combustion PAHs are not significant. We find only modest changes between the glacial and post-glacial sediments for atmospherically transported hydrocarbon biomarkers, while particle associated biomarkers were captured strongly at basin edges during the glacial period, and much more evenly transported across basins during the post-glacial period. The orders of magnitude decreases in particle associated petrogenic alkanes and PAHs in central basins during glacial times, coupled with the uniformity of most petrogenic biomarker parameters for most basin and shelf locations, reflect a massive reduction in ice transport that makes the margins the most likely source of petrogenic material for the Pleistocene/Holocene central Arctic basins. The proximity of large coal deposits of various maturity levels along the Lena River, the overlap in PAH and biomarker composition of the Laptev Sea and surficial sediments from the central Arctic Ocean and the location of the Laptev Sea at the origin of the main Transpolar Drift all point to eroded coals from the Lena River/Laptev Sea as the likely source of petrogenic hydrocarbons to the central Arctic Ocean. The ubiquitous presence of allochthonous coal in Arctic Ocean surface sediments provides a major constraint on the use of petrogenic biomarkers to infer the presence of subsurface petroleum reserves.     

Polycyclic aromatic hydrocarbons in an anoxic sediment core from the Pettaquamscutt River (Rhode Island,U.S.A.)

Fifteen sections from an anoxic sediment core were analyzed for polycyclic aromatic hydrocarbons (PAH). Two types of PAH were observed: (a) those from combustion sources such as pyrene and chrysene and (b) those from natural sources such as retene and perylene. The combustion PAH levels in core sections dated between 1900 and 1970 were much higher than in earlier sections; this indicated an anthropogenic origin of these PAH at this location. The perylene and retene core profiles show significant anomalies during the period 1850–1880. Organic carbon does not fluctuate markedly but δC-13 of organic carbon shows several unexplained excursions; one of which correlates with the perylene and retene anomalies.     

基于层次聚类法和主成分分析法的铜陵市大气降尘污染元素来源解析研究

本文采用层次聚类法和主成分分析法对有色金属矿山城市-铜陵市的大气降尘中污染元素,主要是重金属元素的来源进行了识别,并分析了各来源所占的比例。结果显示,铜陵市大气降尘中污染物主要来源于冶金和采矿,其次为燃煤、交通和土壤扬尘等,其贡献率分别为冶金源+采矿源43.29%,燃煤源32.23%,交通源和土壤源10.53%,其他源13.94%。因此,优先控制冶金尘、采矿尘和燃煤尘,可以有效降低铜陵市大气降尘中污染元素的含量。     

Levels and sources of polycyclic aromatic hydrocarbons (PAHs) in selected irrigated urban agricultural soils in Accra, Ghana

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic pollutants in urban environments including urban soils. Elevated concentrations of PAHs in urban soils are caused by incomplete combustion of petroleum and coal. This study assesses 16 individual PAH compounds in a total of 112 surficial soil samples. The objective was to assess and compare the levels of contamination as well as examine the main sources of PAHs in four urban agricultural soils using molecular ratios of some specific hydrocarbons. The study showed that PAH levels in soil ranged from 1.23 ng/kg in soil collected from Dzorwulu to 2.95 ng/kg in soil collected from Ghana Broadcasting Cooperation (GBC) vegetable irrigation site. Of the total PAHs, the more water soluble PAHs (2–4 rings), which tend to be concentrated in the vapour phase were found to dominate the soils. The percentage dominance were Dzorwulu (52.8 %), Marine Drive (62.5 %), CSIR (53.2 %) and GBC (49.2 %). However, there were significant levels of the more carcinogenic PAHs (5–6 rings) present with percentages as 47.1, 37.5 46.8 and 50.8 % for Dzorwulu, Marine Drive, CSIR and GBC vegetable irrigation sites, respectively, and therefore, may impact negatively on public health. Based on the classification by the Institute of Soil Science and Plant Cultivation in Pulawy, Poland, urban soils in Accra could be classified as contaminated to different levels. Molecular ratios of Flu/pyr and PA/Ant were calculated to determine the main sources of PAHs. Results showed that PAHs could originate mainly from incomplete combustion of petroleum products, especially from atmospheric fallout from automobile exhausts. The study further showed that B(a)P concentration of 0.05 ng/kg in soil from GBC urban vegetable irrigation site requires immediate clean-up exercise and monitoring to mitigate human health impact.     

Biomass burning — a review of organic tracers for smoke from incomplete combustion

Biomass combustion is an important primary source of particles with adsorbed biomarker compounds in the global atmosphere. The introduction of natural product organic compounds into smoke occurs primarily by direct volatilization/steam stripping and by thermal alteration based on combustion temperature. Although the molecular compositions of organic matter in smoke particles are highly variable, the molecular tracers are generally still source specific. Dehydroabietic acid is typically the major tracer for conifer smoke in the atmosphere. Degradation products from biopolymers (e.g. levoglucosan from cellulose, methoxyphenols from lignin) are also excellent tracers. Additional markers of thermally-altered and directly-emitted natural products in smoke have been defined which aids the assessment of the organic matter types and input from biomass combustion to aerosols. The precursor to product approach of compound characterization by organic geochemistry has also been applied successfully to provide source specific tracers for studying the chemistry and dispersion of ambient aerosols and the intermingling of natural with anthropogenic emissions and with smoke plumes. A brief review of the organic matter composition in aerosols derived from the major sources is also given, with emphasis on the detection of biomass burning components. These major sources are the natural background from biogenic detritus (e.g. plant wax, microbes, etc.) and anthropogenic particle emissions (e.g. oils, soot, synthetics, compounds, etc.). The emissions of organic constituents in coal smoke particulate matter are also reviewed and depend on combustion temperature, ventilation, burn time, and coal rank (geologic maturity). The components of peat and brown coal and to a lesser degree semi-bituminous coal consist mainly of hydrocarbons, biomarkers, and aromatic components, quite similar to burning of contemporary biomass. Dispersion from the source and long range transport of smoke particulate matter with the associated organic compounds is also discussed.     

兰州市冬季气溶胶吸光特性研究——黑碳与棕色碳的区分及特征分析

为研究兰州市冬季亚微米气溶胶的吸光特性,利用2014年1月10日至2月4日黑碳仪（AE31）和高分辨率飞行时间质谱仪（HR-ToF-AMS）观测资料,对气溶胶的吸光特性进行了分析。首先根据黑碳气溶胶（BC）和棕色碳气溶胶（BrC）的光学特性差异对二者进行区分,然后分析两者的吸光特性。结果表明：观测期间亚微米气溶胶中黑碳和有机物的平均浓度分别为3.7 μg·m^-3和29.3 μg·m^-3。随着亚微米气溶胶浓度的增加,黑碳和棕色碳吸收系数均增加,但棕色碳吸收系数增加得更快。黑碳和棕色碳在550 nm处的平均吸收系数分别为（9.9±5.9）Mm^-1和（51.0±28.1）Mm^-1。棕色碳的Angstrom指数为4.4。另外,采用正定矩阵因子解析模型（PMF）将棕色碳的来源划分为六种（碳氢类有机气溶胶（HOA）、烹饪类有机气溶胶（COA）、生物质燃烧（BBOA）、燃煤排放（CCOA）、半挥发低氧化程度有机气溶胶（SV-OOA）和低挥发高氧化程度有机气溶胶（LV-OOA））,并通过多元线性回归方法计算了各来源的吸光贡献,其中BBOA和CCOA对棕色碳吸光系数的贡献为41.5%,其次是SV-OOA（32.8%）、LV-OOA（14.2%）、HOA（7.8%）和COA（3.8%）,说明一次和二次有机气溶胶均为兰州地区棕色碳的重要来源。     

石家庄市大气降尘重金属元素来源分析

本文对石家庄市大气降尘重金属含量水平进行了研究,从2007年11月起连续收集一年的大气降尘样品,分析了As、Cd、Hg、Pb、Cr、Cu、Zn、Ni、Mo、Mn、Al2O3、K2O等12项。结果表明,与土壤背景值相比,石家庄市大气降尘中除Al2O3外的重金属含量总体明显升高。采用相关分析和主成分分析,对降尘重金属元素来源进行解析,认为有3种主要来源:一是Pb、Cr、As、Hg、Mo、Cd、Mn与燃煤活动、道路交通有关;二是Ni、Cu、Zn除与燃煤活动有关外,还与工矿企业废气排放有关;三是Al2O3主要与土壤颗粒物有关(自然来源)。以Al作为参考元素计算重金属的富集因子表明,受工业活动影响的Cd、Hg、Zn具有较大的富集因子,大气降尘中的重金属含量高值区与工业区域的分布相吻合。