Polycyclic Aromatic Hydrocarbons Load Research Articles

Distribution and deposition of polycyclic aromatic hydrocarbons in precipitation in Guangzhou, South China

Polycyclic aromatic hydrocarbons (PAHs) were measured in precipitation from March to August 2005 in Guangzhou, South China. Fourteen PAHs were studied, and their total concentrations varied from 616.6 to 3486.7 ng/L in dissolved phase and from 403.8 to 3125.5 ng/L in particulate phase. The estimated deposition loading of PAHs was 3568 μg/m 2 during the monitoring period. The deposition of PAHs was a potential source for Pearl River comparing with the contents of surface water. In addition, the high concentration in precipitation here implied that PAHs pollution was a potential environmental problem in Guangzhou. Most precipitation concentrations of PAHs in March (the last month in winter in Guangzhou) were higher than in the other months (in rainy season). PAHs inclined to be adsorbed to particulate phase with the increase of molecular weight in rainwater. Combustion of fossil fuel and biomass might be the major source of PAHs, while the direct leakage or volatilization from petroleum products might be insignificant.

Evaluation of polyaromatic hydrocarbon removal from aqueous solutions using activated carbon and hyper‐crosslinked polymer (Macronet MN200)

AbstractBACKGROUND: Sorption of polycyclic aromatic hydrocarbons (PAHs) on activated carbon and the Macronet polymeric sorbent MN200 was investigated to determine the effectiveness of each sorbent for removal of pollutants from aqueous solution and their possible use as sorbent materials for groundwater. Experiments were carried out to determine the loading capacities of a family of PAHs (acenaphthene, anthracene, fluoranthene, fluorene, naphthalene and pyrene).RESULTS: Activated carbon was the more effective sorbent, with maximum loadings of PAHs between 90 and 230 g kg−1, while MN200 resin showed values of 25–160 g kg−1. Loading isotherms based on the Langmuir, Freundlich and Redlich–Peterson models were determined. The hydrophobic character of the pollutants appeared as an important parameter related to the sorption process. Equilibrium and kinetic parameters were used to determine the retardation factors for each PAH.CONCLUSION: The calculated values for the simulation of barrier thickness using both sorbents, taking into account EU requirements for PAHs in groundwater effluent, were perfectly reasonable as a first estimate. The better kinetic properties of MN200 are evident in lower hydraulic residence times and consequently in a lower barrier thickness. Copyright © 2008 Society of Chemical Industry

A comparison of concentrations of polycyclic aromatic compounds detected in dust samples from various regions of the world

Settled house dust can be a source of human exposure to toxic polycyclic aromatic hydrocarbons (PAHs) through non-dietary ingestion and dermal contact. Information regarding the concentrations of various contaminants in house dust would be useful in estimating the risk associated with exposure to these compounds. This study reports on the surface loading, variability and distribution of PAHs in settled house dust collected from homes in three locations: Sumgayit, Azerbaijan; Shanxi Province, China; and southern Texas, United States. The highest PAH floor surface loadings were observed in China, followed by Azerbaijan and Texas. Median concentrations of high molecular weight (four ring and larger) PAHs ranged from a low of 0.11 µg/m 2 in Texas, to 2.9 µg/m 2 in Azerbaijan and 162 µg/m 2 in China. These trends in total surface loading and relative carcinogenicity indicate that the risk of health effects from exposure to PAHs in house dust is highest in the Chinese population and lowest in the Texas population. As anticipated, variability among dust samples from different houses within the same region was high, with coefficients of variation greater than 100%. Alkylated PAHs comprised 30–50% of the total mass of PAHs. Based on a comparison of the composition of specific components, PAHs in China and Azerbaijan were determined to be derived mainly from combustion sources rather than from unburned fossil fuels such as petroleum. These results, coupled with ongoing investigation of appropriate PAH exposure biomarkers in humans, will guide future efforts to identify ways to reduce exposures in the study areas.

Oceanic loading of wildfire‐derived organic compounds from a small mountainous river

Small mountainous rivers (SMRs) export substantial amounts of sediment into the world's oceans. The concomitant yield of organic carbon (OC) associated with this class of rivers has also been shown to be significant and compositionally unique. We report here excessively high loadings of polycyclic aromatic hydrocarbons (PAHs), lignin, and levoglucosan, discharged from the Santa Clara River into the Santa Barbara Channel. The abundance of PAHs, levoglucosan, and lignin in Santa Barbara Channel sediments ranged from 201.7 to 1232.3 ng gdw−1, 1.3 to 6.9 μg gdw−1, and 0.3 to 2.2 mg per 100 mg of the sedimentary OC, respectively. Assuming a constant rate of sediment accumulation, the annual fluxes of PAHs, levoglucosan, and lignin, to the Santa Barbara Channel were respectively, 885.5 ± 170.2 ng cm−2 a−1, 3.5 ± 1.9 μg cm−2 a−1 and 1.4 ± 0.3 mg per 100 mg OC cm−2 a−1, over ∼30 years. The close agreement between PAHs, levoglucosan, and lignin abundance suggests that the depositional flux of these compounds is largely biomass combustion‐derived. To that end, use of the Santa Clara River as a model for SMRs suggests this class of rivers may be one of the largest contributors of pyrolyzed carbon to coastal systems and the open ocean. Wildfire associated carbon discharged from other high yield fluvial systems, when considered collectively, may be a significant source of lignin, pyrolytic PAHs, and other pyrogenic compounds to the ocean. Extrapolating these methods over geologic time may offer useful historical information about carbon sequestration and burial in coastal sediments and affect coastal carbon budgets.

PAHs in Stockholm window films: Evaluation of the utility of window film content as indicator of PAHs in urban air

The thin organic film that builds up on the exterior surface of windows has been proposed as a ubiquitously available passive sampler for semi-volatile organic contaminants (SOCs) in urban air. Readily available school windows were sampled in Stockholm city centre and suburban locations in both winter and summer season to evaluate the putative usefulness of this matrix for assessing the integrated load of urban air pollution by polycyclic aromatic hydrocarbons (PAHs). The window-area normalised concentrations indicated more PAH contamination in the winter than in the summer in both the city centre and suburban locations, with highest concentrations in the city centre in the winter (∑PAH 43 451–467 ng m −2). However, normalising the PAH load to the amount of fatty window film, as measured by extractable organic matter (EOM), gave a more homogeneous picture with the EOM-normalised PAH load being inseparable both between summer and winter and between city centre and suburban locations. To evaluate the possibility of quantitatively employing urban window films as a means to provide predicted environmental concentrations of PAHs in air (PEC air), window film–air partition coefficients of PAHs were estimated using a set of coupled linear free energy relationships and physico-chemical properties of PAHs. Assuming dynamic equilibria between PAHs in air and dissolved in the window film, the obtained PEC air from the window films were consistently overestimating the urban vapour-phase PAH concentrations by factors 4–135. This discrepancy is quantitatively consistent with a strong and overwhelming association with black carbon aerosol particles accumulated in the window film. For SOCs that have a lower tendency to associate with black carbon, bulk window film concentrations may work better than for PAHs to estimate their vapour-phase concentrations in urban air.

Assessment of atmospheric PAHs profile through Calotropis gigantea R.Br. leaves in the vicinity of an Indian coal-fired power plant

Biomonitoring of polycyclic aromatic hydrocarbons (PAHs) in the leaves of Calotropis gigantea R.Br. were performed at seven sites in the surrounding areas of a Thermal Power Plant (TPP), using the gas chromatography and mass spectrometry technique. The primary objective of the study was to monitor the degree of PAHs load in the nearby sites around TPP compared to distant sites. Total PAH (SigmaPAH) concentrations in the leaves ranged from 372.18 (at control site 7) to 4362.35 ng g(-1) d.w. (at highest polluted site 4). The concentration factors ranged from 2.65 to 11.72 for the sites located at 1 km to the point source and 1.0 to 7.08 for distant sites. The share of carcinogenic PAHs to the total PAHs differed with the site, ranging from 10.76% to 26.92%. The sites located closer to TPP have shown higher concentrations of medium and high molecular weight PAHs, which decreased gradually with the distance from the source. The total PAH burden at control site was dominated by the low and medium molecular weight PAHs compounds viz., naphthalene, acenaphthylene, acenaphthene, phenanthrene, fluoranthene, pyrene, chrysene, coronene., whilst at other sites medium and high PAHs viz., fluoranthene, pyrene, benzo (a) anthracene, chrysene, benzo (b) fluoranthene, benzo (e) pyrene and coronene showed the highest values. These results support the biomonitoring ability of Calotropis gigantea R.Br. leaves to monitor PAHs contamination.

Phototoxicity of Pyrene Affects Benthic Algae and Bacteria from the Arctic

Phototoxicity of polycyclic aromatic hydrocarbons (PAHs) in the Arctic is important to study since the future PAH load is likely to increase. In combination with the increased UV-light penetration due to ozone layer thinning, phototoxicity may be a potential problem for arctic areas. The aim of this study was to evaluate effects of pyrene and phototoxicity of pyrene on natural algae and bacteria from arctic sediments. Sediments from a shallow-water marine baywere spiked with different pyrene concentrations. Microcosms containing the sediment were incubated under three light regimes, natural sunlight with UV-light, natural sunlight without UV-light, and dark. Significant effects were evident at low pyrene concentrations, particularly in presence of UV-light, indicating phototoxicity. The microalgae were especially sensitive to the phototoxicity of pyrene. Already atthe lowest pyrene concentration (Cfree: 4 nM) algal 14C-incorporation and chlorophyll a content were reduced. The toxic effects of pyrene on the microalgae probably led to the release of organic matter. In agreement with this, bacterial activity increased at high pyrene concentrations indicated by increased oxygen consumption and increased release of inorganic N and P from the sediment. This study indicates that phototoxicity of PAHs may be relevant for sediment communities from shallow marine arctic areas at environmentally relevant pyrene concentrations.

Characterization and loading estimation of polycyclic aromatic hydrocarbons in road runoff from urban regions of Beijing, China

This paper reports an initial study regarding our quantitative understanding of the characteristics of polycyclic aromatic hydrocarbon (PAH) contamination and loading estimation from road runoff in Beijing (China). The concentrations of 16 PAHs were measured in road runoff and rainwater in a composite commercial and residential catchment of Beijing in 2006. In road runoff samples, geometric mean concentrations of Sigma16 PAHs (the sum of 16 PAH concentrations) in the dissolved and particle phases were 548.2 and 3,872.2 ng/L, respectively, and in rainwater samples, the concentrations in the dissolved and particle phases were 172.9 and 274.6 ng/L, respectively. An analysis on spatial variation among the sampling sites showed that PAH concentrations at the branch road (with low traffic volume) were higher than those at the trunk road (with high traffic volume) and that PAH contamination at the bicycle lane was comparable to that at the vehicle lane. Dimensionless cumulative analyses indicated that first flush effect did not occur in all cases, but rather depended on storm event characteristics. According to the annual unit loading rate and the planned road area, the relative magnitude of PAH loading in road runoff was in the following order: Vehicle lane of trunk road > branch road > bicycle lane of trunk road.

Variation in PAH inputs and microbial community in surface sediments of Hamilton Harbour: Implications to remediation and monitoring

Variations in concentrations of polycyclic aromatic hydrocarbons (PAHs) and microbial community indicators were investigated in representative highly contaminated and less contaminated surface sediment sites of Hamilton Harbour. Inputs of PAH to the upper 3 cm of sediments up to four times the average upper sediment concentrations were observed. Associated PAH fingerprint profiles indicated that the source was consistent with the PAH source to the industrial region of the harbour. Increased PAH loadings were associated with decreased bacterial populations as indicated by phospholipid fatty acid (PLFA) concentrations. However, relatively minor impacts on overall community composition were indicated. Porewater methane concentrations and isotopic data indicated a difference in the occurrence of methane oxidation between the two sites. This study confirms temporally limited transport of contaminants from highly impacted regions as a vector for contaminants within the harbour and the impact on microbial carbon cycling and bed stability.

Polycyclic aromatic hydrocarbon (PAH) content of soil and olives collected in areas contaminated with creosote released from old railway ties

Simple sample preparation procedures involving sonication and solid phase extraction (SPE), followed by reversed-phase high performance liquid chromatography (HPLC) and spectrofluorometric detection, were used to analyse polycyclic aromatic hydrocarbons (PAHs) in soil and olives collected in areas contaminated with creosote-treated railway ties. Very high PAH contents (with amounts ranging from 114.7 to 2157.2 and from 167.3 to 3121.8 microg kg(-1) dry weight for total light PAHs and total heavy PAHs, respectively) were found in soil sampled up to 1 m from the source of contamination. The PAH load decreased rapidly with the distance from the railway ties. High amounts of light PAHs, up to 6359.9 microg kg(-1), were also found in oil extracted from olives collected in a rural area where old railway ties were stored. No appreciable transfer of heavy PAHs and benzo[a]pyrene was observed in oil samples.

諏訪湖における多環芳香族炭化水素類の年間収支の推定

In the present study, we estimated inflow and effluent load of Polycyclic Aromatic Hydrocarbons (PAHs) in Lake Suwa, Japan. Estimation of PAHs inflow and effluent load were performed by measuring changes in stream flow and concentration of suspended solids (SS) in the lake and river water. Results showed that the concentration of SS increased with stream flow. Annual (March 2004 to February 2005) inflow and effluent load of SS at the lake were calculated as 8.9×106 kg and 7.6×106 kg, respectively. The mass balance between inflow and effluent load indicated that 1.3×106 kg of SS were sedimentated to the lake. The total amount of Σ9PAHs (Phenanthrene, Pyrene, Chrysene, Benzo[e]pyrene, Benzo[b]fluoranthene, Benzo[k]fluoranthene, Benzo[a]pyrene, Dibenz[a,h]anthracene, Benzo[ghi]perylene) in lake SS varied by 230±120 g/lake (average±SD); the maximum amount exceeded 500 g/lake, which was observed in May and October 2004. Specifically, for Benzo[a]pyrene the total amount in lake SS was 14±7 g/lake. Estimation of total Σ9PAHs flowing into Lake Suwa and out through Kamaguchi Gate indicated Σ9PAHs values of 8.6 and 3.5 kg/yr, respectively. The mass balance between Σ9PAHs inflow and outflow indicated that approximately 5.1 kg/yr of Σ9PAHs were sedimentated with SS to the lake. The annual flux of PAHs in Lake Suwa calculated in the present study agreed with the deposition flux of PAHs in a previous study estimated from sediment cores (4 kg/yr) (Ikenaka et al.: Environ. Pollut., 138, 530-538 (2005)). Inflow loads of PAHs markedly increased in May 21, October 9, and October 21 when heavy rains occurred, occupying approximately 27 % of the annual inflow. These results indicated that large quantities of PAHs flowed into the lake when river flow increased by heavy rain.

Polycyclic aromatic hydrocarbons (PAHs) in the air of Chinese cities

Polycyclic aromatic hydrocarbons (PAHs) were determined in the air of 37 cities and 3 rural locations across China during the winter, spring, summer and autumn of 2005, using polyurethane foam (PUF) disks as passive air samplers (PAS). Winter and autumn concentrations in cities exceeded spring and summer values. Concentrations were amongst the highest in the world; seasonally averaged autumn/winter values in some cities in the north and north-west of China exceeded proposed European Union air quality standards. Several factors, acting in combination, influenced air concentrations. A significant negative correlation was found between average annual city concentrations and the annual average temperature, while winter time PAH concentrations correlated with estimated coal consumption. The highest total PAH concentrations and loadings of high molecular weight compounds generally occurred in major cities located on higher land (500-2000 m), where relatively cold winters and higher coal consumption occurs. Lower values occurred in cities located in the south and east China and along the coastal regions. Molecular markers indicated incomplete combustion of fossil fuels dominated the urban air and gave evidence for photo-decomposition of selected compounds.

Polycyclic aromatic hydrocarbon (PAH) contamination in San Francisco Bay: A 10-year retrospective of monitoring in an urbanized estuary

Polycyclic aromatic hydrocarbons (PAH) are widespread contaminants in the San Francisco Bay. Several exceedances of water quality criteria raise the possibility that PAH may be impacting aquatic biota. The Regional Monitoring Program for Water Quality in the San Francisco Estuary (RMP) has collected annual monitoring data on PAH in the Bay since 1993. Analysis of Bay water, sediment, and mussel ΣPAH concentration data showed that there were very few significant ( P<0.05) increasing or decreasing temporal trends in ΣPAH concentrations in the Bay during the period of 1993–2001. Wet and dry season input of PAH did not show any major influence on water ΣPAH concentrations over the same period. Based on their relative contribution to the estimated total maximum PAH loading (10,700 kg/yr) into the Bay, the PAH loading pathways are ranked as storm water runoff (∼51%)>tributary inflow (∼28%)>wastewater treatment plant effluent (∼10%)>atmospheric deposition (∼8%)>dredged material disposal (∼2%). The PAH sediment quality threshold of 1000 ng/g, which has been previously suggested by NOAA to protect estuarine fish such as English sole against adverse health effects, was frequently exceeded at individual monitoring stations (11 of the 26 stations exceeded the threshold over 50% of the time). Modeling results have shown that the predominant loss pathway for PAH is degradation in sediments, and unless external loading levels of PAH are controlled, the Bay is not expected to recover rapidly.

Characterization and Source Assessment of Heavy Metals and Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments of the Fosu Lagoon, Ghana

The first results ever obtained on polycyclic aromatic hydrocarbon (PAHs) concentrations in the Fosu lagoon surface sediments are presented together with corresponding heavy metal (Fe, Mn, Cd, Zn and Ni) concentrations. Samples collected on a monthly basis from November 2003–April 2004 (Heavy metals) and December 2003–January 2004 (PAHs) at 8 locations, representing different anthropogenic sources of contamination to the lagoon, were analyzed. Concentrations of Cd and Ni in the lagoon sediment suggest greater contamination to the lagoon from industrial activities in the vicinity of the lagoon; 50% of the sediment samples exceeded some established sediment Cd guidelines for the protection of aquatic lives. Then, 15 PAHs were detected among the sediments from the different locations and the compositional pattern in decreasing order was 3-ring > 5-ring > 4-ring > 6-ring > 2-ring PAH compounds. Σ PAH concentrations in the sediment samples ranged from 254 to 558 mg/kg, with a mean of 359.4 mg/kg. Two distinct areas were identified to be a major source of anthropogenic load of both heavy metals and PAH; the mechanical shop in the northeastern sector of the lagoon is the main location for the input of Cd and it's associated PAH compounds (e.g., acenapthylene, acenaphthene, naphthalene and benzo[a]fluoranthene) and to a lesser extent Ni. Both combustion and petroleum sources may account for PAH loads from this area. The residential area in the northern sector is responsible for high loads of Mn and its associated PAH compounds (e.g., phenanthrene, benzo[a]pyrene and anthracene). These chemicals seem to enter the lagoon mainly by the combustion of especially wood or coal.

Attenuation of polycyclic aromatic hydrocarbons from urban stormwater runoff by wood filters

A significant amount of contamination enters water bodies via stormwater runoff and, to reduce the amount of pollution, retention ponds are installed at many locations. While effective for treating suspended solids, retention ponds do not effectively remove dissolved constituents, such as polycyclic aromatic hydrocarbons (PAH). Previous laboratory studies demonstrates that aspen wood cuttings can be utilized to enhance the removal of dissolved contaminants. The objective of this pilot-scale field test was to determine if wood filters could effectively remove dissolved PAH from the runoff under field conditions. Four wood filter tests were conducted, lasting from 1 to 9 weeks, to determine the degree of PAH attenuation from the aqueous phase as a function of wood mass, residence times, and seasonable changes. The prototype wood filters removed on average between 18.5% and 35.6% (up to 66.5%) of the dissolved PAH contaminants. The PAH removal effectiveness of the wood was not affected by changes in water temperature or pH. The filter effectiveness increased with filter size and was highest in continuously submerged parts of the filter system. Also, heavier molecular weight PAH compounds (e.g. chrysene) were more effectively removed than lighter molecular weight compounds. Disassociation of weakly particle-bound PAH from the filter was identified as the most likely cause for a temporary drop of the wood filter's PAH load during intense storms. Simple filter design changes are likely to double the filter effectiveness and alleviate the disassociation problem.

Spatial variability of polycyclic aromatic hydrocarbon load of urban wet weather pollution in combined sewers

In Paris, the OPUR research programme created an experimental on-site observatory of urban pollutant loads in combined sewer systems in order to characterise the dry and wet weather flows at different spatial scales. This article presents the first results on the spatial variability of the polycyclic aromatic hydrocarbon (PAH) load during wet weather flow (WWF). At the scale of a rain event, investigations revealed that (i) PAH concentrations were relatively homogenous whatever the spatial scale and were greater than those of the dry weather flow (DWF), (ii) PAH distributions between dissolved and particulate phases were constant, and (iii) PAH fingerprints exhibited a similar pattern for all catchments. Moreover, an evaluation of the contribution of DWF, runoff and erosion of sewer deposits to WWF load was established. According to the hypothesis on the runoff concentration, the contributions were evaluated at 14, 8 and 78%, respectively, at the scale of the Marais catchment. For all the catchments, the runoff contribution was found quite constant and evaluated at approximately 10%. The DWF contribution seems to increase with the catchment area, contrary to the sewer erosion contribution, which seems to decrease. However, this latter still remains an important source of pollution. These first trends should be confirmed and completed by more investigations of rain events.

Role of Weathered Coal Tar Pitch in the Partitioning of Polycyclic Aromatic Hydrocarbons in Manufactured Gas Plant Site Sediments

Polycyclic aromatic hydrocarbons (PAHs) in manufactured gas plant (MGP) site sediments are often associated with carbonaceous particles that reduce contaminant bioavailability. Although black carbon inclusive partitioning models have been proposed to describe elevated PAH partitioning behavior, questions remain on the true loading and association of PAHs in different particle types in industrially impacted sediments. In the studied MGP sediments, the light density organic particles (coal, coke, wood, and coal tar pitch) comprised 10-20% of the total mass and 70-95% of the PAHs. The remainder of the PAHs in sediment was associated with the heavy density particles (i.e., sand, silt, and clays). Among the different particle types, coal tar pitch (quantified by a quinoline extraction method) contributed the most to the bulk sediment PAH concentration. Aqueous partition coefficients for PAHs measured using a weathered pitch sample from the field were generally an order of magnitude higher than reported for natural organic matter partitioning, and match well with theoretical predictions based on a coal tar-water partitioning model. A pitch-partitioning inclusive model is proposed that gives better estimates of the measured site-specific PAH aqueous equilibrium values than standard estimation based on natural organic matter partitioning only. Thus, for MGP impacted sediments containing weathered pitch particles, the partitioning behavior may be dominated by the sorption characteristics of pitch and not by natural organic matter or black carbon.

제주시 토양 중 다환방향족탄화수소류(PAHs)의 분포 특성

Sixteen soil samples around six areas (residental area, traffic area, power plant area, incineration area and factory area) where the stationary and mobile sources of polycyclic aromatic hydrocarbons (PAHs) are estimated to be emitted in Jeju City, were collected during Feburuary to March, 2004, and analyzed for 16 PAHs recommended by US EPA as primary pollutants to investigate their distribution characteristics. The concentrations of total PAHs (t-PAHs) and total carcinogenic PAHs in soils of Jeju City were in the range of on a dry weight basis with a mean value of 87.2 ng/g and with a mean value of 33.4 ng/g, respectively. The concentrations of t-PAHs were low in comparison with those in soils of other domestic and foreign countries. The mean concentrations of t-PAHs and with area decreased in the following sequences: traffic area> incineration area > factory area > power generation area > harbor area enli residental area. The correlation between t-PAHs and were very high , indicating that concentration increases in proportion with t-PAHs. Comparing the distribution ratio of ring PAHs with area among 16 PAHs, it decreased in the order of 4-ring > 5-ring > 6-ring > 3-ring > 2-ring in all the areas except for harbor area. whitens for harbor area it was similar among 3-, 4- and 5-ring with high value. Low and no correlations between t-PAHs and soil compositions (organic matter content and particle size distribution) were observed, which is considered to be caused by the complex factors, such as the loading and characteristics of PAHs and diverse soil environment change, etc. From the examination of the three PAH origin indices, such as LMW/HMW (low molecular weight ring PAHs over high molecular weight ring PAHs), phenanthrene/anthracene ratio and fluoranthene/pyrene ratio, it can be concluded that the soil PAH contaminations were ascribed to strong pyrogenic origin in ail areas except for harbor area and to both pyrogenic and petrogenic origins.

Watershed‐based sources of polycyclic aromatic hydrocarbons in urban storm water

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutagenic compounds, ubiquitous in the air and water of urban environments, and have been shown to accumulate in coastal estuarine and marine sediments. Although previous studies have documented concentrations and loads of PAHs in urban runoff, little is known about the sources and temporal patterns of PAH loading from storm water. This study characterized the sources and temporal patterns of PAHs in urban storm water by analyzing PAH concentrations and loads from a range of homogeneous land use sites and in-river mass emission sites throughout the greater Los Angeles, California, USA, region. Samples were collected at 30- to 60-min intervals over the course of a storm during multiple storm events over a four-year period in order to investigate PAH sources and inter- and intrastorm patterns in loading. Polycyclic aromatic hydrocarbon storm fluxes ranged from 1.3 g/km2 for the largely undeveloped Arroyo Sequit watershed to 223.7 g/km2 for the highly urbanized Verdugo Wash watershed, with average storm fluxes being 46 times higher in developed versus undeveloped watersheds. Early-season storms repeatedly produced substantially higher loads than comparably sized late-season storms. Within individual storms, PAHs exhibited a moderate first flush with between 30 and 60% of the total PAH load being discharged in the first 20% of the storm volume. The relative distribution of individual PAHs demonstrated a consistent predominance of high-molecular-weight compounds indicative of pyrogenic sources.

Distribution and loadings of polycyclic aromatic hydrocarbons in the Xijiang River in Guangdong, South China

The Xijiang River is the major tributary of the Pearl River, South China, and is the major source water system for more than 4.5 million of urban population and 28.7 million of rural population. We initiated a systematic study on detection and quantification of organic pollutants in both water and suspended particulate matter (SPM) for samples collected in a span of 12 months. Our results showed that total concentrations of 15 polycyclic aromatic hydrocarbons (PAHs) varied from 21.7 to 138 ng l −1 in water and from 40.9 to 665 μg kg −1 in SPM. The organic carbon normalized distribution coefficients ( K OC) computed for the PAHs were correlated well with their octanol–water partition coefficient ( K OW). The estimated annual loadings of Ant, B aA, and B ghiP and the total PAHs in the Xijiang River were 1620, 330, 177 and 19 400 kg, respectively. Further analysis of the data showed that combustion may be the major source of PAHs and that direct leakage of petroleum products may be insignificant.