Marine microplastics in the surface waters of "pristine" Kuroshio.

Microplastics (MPs) are ubiquitous in oceans. Their transboundary transport and fate have aroused global attention. Taiwan is located close to the western boundary current-Kuroshio, is an excellent location to study of MP mobility in the global current and Pacific Garbage Patch. This study is the first investigation to understand the microplastic contamination from Taiwan to the Kuroshio. MP concentrations in the area varied from N.D. to 0.15 items m-3, with an average concentration of 0.05 ± 0.03 items m-3. The majority of MPs were polypropylene, polyethylene, polyethylene and terephthalate. We found two MP hotspots near the coastal zone. One additional hotspot was also identified in the "pristine" Kuroshio suggesting rivers and local currents may play critical roles in transporting or injecting MPs from Taiwan into the North Pacific Gyre. These findings suggest that marine environments are altered by anthropogenic disposal and provide needed data for modelling and prediction of MPs.

Distribution of mercury and methylmercury in surface water and surface sediment of river, irrigation canal, reservoir, and wetland in Taiwan.

In Taiwan, because of the co-use of some irrigation and drainage canals, a portion of industrial wastewater was directly discharged into irrigation canals or even flowed into rivers or wetlands, causing the heavy metal pollution in waters and sediments. Mercury (Hg) contamination in rivers, irrigation canals, and wetlands has been found in Taiwan, but a thorough investigation on the distribution of Hg and methylmercury (MeHg) in these waters and sediments, which may be present in a greater level with elevating total Hg (THg) concentration and markedly impact human health, is still lacking. In this study, surface waters and surface sediments were sampled from five major rivers, two irrigation canals, two reservoirs, and one wetland in Taiwan, and their THg and MeHg concentrations were quantified. Additionally, statistical analysis was carried out to understand the relationship between sediment properties and MeHg levels. The results showed that irrigation canal sediments were relatively more polluted by Hg and the THg concentrations of some sampling points exceeded the upper limit (i.e., 0.87 mg kg-1) of sediment quality index (SQI) for THg promulgated by Taiwan Environmental Protection Administration, which may be attributed to the co-use of irrigation and drainage canals. Furthermore, the MeHg concentration in irrigation canal sediments was the highest; rivers came in second followed by wetlands. In addition, the Siangshan Wetland was analyzed to have the greatest THg and MeHg concentrations in its surface water. Linear regression analysis also indicated that total organic carbon and clay content substantially affected the MeHg production in sediments.

Alkylphenol ethoxylate metabolites in coastal sediments off southwestern Taiwan: Spatiotemporal variations, possible sources, and ecological risk.

Alkylphenol ethoxylates (APEOs) are one of the most widely used classes of surfactants, but they are also ubiquitous environmental pollutants and known endocrin-disrupting chemicals. This study is the first to investigate the spatiotemporal variations and possible sources of APEOs and their metabolites, including nonylphenol ethoxylates (NPEOs) and octylphenol ethoxylates (OPEOs), in coastal sediments off southwestern Taiwan. The highest APEO concentration in the dry season was observed for the Kaohsiung coastal area, whereas the highest alkylphenol (AP) concentration in the wet season was found offshore at the Tainan Canal exit. No continuous accumulation of alkylphenol metabolites was evident in the area. One possible reason is that seasonal current and wind waves disperse the coastal pollutants. Application of multivariate statistical tools (hierarchical cluster analysis and principal component analysis) confirmed the role of rivers and the Tainan Canal in transporting contaminants to coastal environments, suggesting influences of industrial and human activities on APEO distribution. A further comparison with the predicted no-effect concentrations (PNECs) proposed by the European Union indicates that nonylphenol (NP) and octylphenol (OP) might pose potential ecological risks to the aquatic environment in the studied area. These findings provide useful information for environmental policy implementation and ecological assessments of different types of endocrine-disrupting chemicals and raise warnings about surfactant applications.

Role of Dissolved Organic Matter in Sorption of Perfluorooctanoic Acid to Metal Oxides.

Perfluorooctanoic acid (PFOA) is an important perfluorinated chemical of significant environmental concern. It has been widely found at high concentrations in the environment. We have exposed sediment constituent minerals SiO2, Fe2O3, and Al2O3 to PFOA and humic acid (HA) and studied the adsorption of PFOA by introducing the adsorbates in different orders. The results suggest concurrent sorption of PFOA and HA to the mineral surface or enhanced PFOA sorption when both are introduced to the aqueous phase. However, when PFOA is introduced to the mineral surface that has already been exposed to and extensively coated with HA, little PFOA adsorption occurs, which implies that PFOA released to rivers rich in dissolved organic matter (DOM, i.e. HA) may be immune to sorptive retention by the sediment and be transported downstream unabated. DOM thus can play a significant role in the transport and fate of PFOA in the natural water system.

Atmospheric polycyclic aromatic hydrocarbons (PAHs) of southern Taiwan in relation to monsoons.

The concentrations and gas-particle partitioning of atmospheric polycyclic aromatic hydrocarbons (PAHs) were intensively measured in the Hengchun Peninsula of southern Taiwan. The concentrations of total PAH (Σ38PAH), including gas and particle phases, ranged from 0.85 to 4.40 ng m(-3). No significant differences in the PAH levels and patterns were found between the samples taken at day and at night. The gas phase PAH concentrations were constant year-round, but the highest levels of particle-associated PAHs were found during the northeast monsoon season. Long-range transport and rainfall scavenging mechanisms contributed to the elevated levels in aerosols andΣ38PAH concentrations. Results from principal component analysis (PCA) indicated that the major sources of PAHs in this study were vehicular emissions. The back trajectories demonstrated that air mass movement driven by the monsoon system was the main influence on atmospheric PAH profiles and concentrations in the rural region of southern Taiwan. Gas-particle partition coefficients (K p ) of PAHs were well-correlated with sub-cooled liquid vapor pressures (P (o) L ) and demonstrated significant seasonal variation between the northeast (NE) and the southwest (SW) monsoon seasons. This study sheds light on the role of Asian monsoons regarding the atmospheric transport of PAHs.

Source contributions and mass loadings for chemicals of emerging concern: Chemometric application of pharmaco-signature in different aquatic systems.

To characterize the source contributions of chemicals of emerging concern (CECs) from different aquatic environments of Taiwan, we collected water samples from different aquatic systems, which were screened for 30 pharmaceuticals and illicit drugs. The total estimated mass loadings of CECs were 23.1 g/d in southern aquatic systems and 133 g/d in central aquatic systems. We developed an analytical framework combining pollutant fingerprinting, hierarchical cluster analysis (HCA), and principal component analysis with multiple linear regression (PCA-MLR) to infer the pharmaco-signature and source contributions of CECs. Based on this approach, we estimate source contributions of 62.2% for domestic inputs, 16.9% for antibiotics application, and 20.9% for drug abuse/medication in southern aquatic system, compared with 47.3% domestic, 35.1% antibiotic, and 17.6% drug abuse/medication inputs to central aquatic systems. The proposed pharmaco-signature method provides initial insights into the profile and source apportionment of CECs in complex aquatic systems, which are of importance for environmental management.

The effects of flow rate and temperature on SPMD measurements of bioavailable PAHs in seawater.

This work investigates the dependence of the sampling rate (Rs) of semi-permeable membrane devices (SPMDs) on flow rate and temperature. The in situ Rs values were obtained using performance reference compounds (PRCs) with weighted polynomial regression and used to estimate the bioavailable polycyclic aromatic hydrocarbon (PAH) concentrations in seawater. The in situ Rs values did not vary with flow rate and temperature. The empirical equation of the Rs value from the SPMDs was established. This infers that PRCs could be avoided by using an established empirical equation under similar field conditions. The sum of the bioavailable PAHs ranged from 0.281 to 0.611ngL(-1) on the eastern side of the Taiwan Strait and from 0.438 to 1.10ngL(-1) on the western side. Distinct sources and toxicity of these bioavailable PAHs were observed and mainly resulted from different types of energy consumption.

Source apportionment and risk assessment of emerging contaminants: an approach of pharmaco-signature in water systems.

This paper presents a methodology based on multivariate data analysis for characterizing potential source contributions of emerging contaminants (ECs) detected in 26 river water samples across multi-scape regions during dry and wet seasons. Based on this methodology, we unveil an approach toward potential source contributions of ECs, a concept we refer to as the "Pharmaco-signature." Exploratory analysis of data points has been carried out by unsupervised pattern recognition (hierarchical cluster analysis, HCA) and receptor model (principal component analysis-multiple linear regression, PCA-MLR) in an attempt to demonstrate significant source contributions of ECs in different land-use zone. Robust cluster solutions grouped the database according to different EC profiles. PCA-MLR identified that 58.9% of the mean summed ECs were contributed by domestic impact, 9.7% by antibiotics application, and 31.4% by drug abuse. Diclofenac, ibuprofen, codeine, ampicillin, tetracycline, and erythromycin-H2O have significant pollution risk quotients (RQ>1), indicating potentially high risk to aquatic organisms in Taiwan.

Impacts of emerging contaminants on surrounding aquatic environment from a youth festival.

The youth festival as we refer to Spring Scream, a large-scale pop music festival, is notorious for the problems of drug abuse and addiction. The origin, temporal magnitudes, potential risks and mass inputs of emerging contaminants (ECs) were investigated. Thirty targeted ECs were analyzed by solid-phase extraction and liquid chromatography coupled to tandem mass spectrometry (SPE-LC-MS/MS). Sampling strategy was designed to characterize EC behavior in different stages (before and after the youth festival), based on multivariate data analysis to explore the contributions of contaminants from normal condition to the youth festival. Wastewater influents and effluents were collected during the youth festival (approximately 600 000 pop music fans and youth participated). Surrounding river waters are also sampled to illustrate the touristic impacts during peak season and off-season. Seasonal variations were observed, with the highest concentrations in April (Spring Scream) and the lowest in October (off-season). Acetaminophen, diclofenac, codeine, ampicillin, tetracycline, erythromycin-H2O, and gemfibrozil have significant pollution risk quotients (RQs > 1), indicating ecotoxicological concerns. Principal component analysis (PCA) and weekly patterns provide a perspective in assessing the touristic impacts and address the dramatic changes in visitor population and drug consumption. The highest mass loads discharged into the aquatic ecosystem corresponded to illicit drugs/controlled substances such as ketamine and MDMA, indicating the high consumption of ecstasy during Spring Scream.

Measuring bioavailable PAHs in estuarine water using semipermeable membrane devices with performance reference compounds.

Bioavailable polycyclic aromatic hydrocarbon (PAH) concentrations in the estuarine water of Kaohsiung Harbor were measured using XAD-2 resin and semipermeable membrane devices (SPMDs) calibrated with performance reference compounds (PRCs). The sum of the PAH concentrations from XAD-2 resin (Cw) in the surface and bottom water samples was 6.63 and 9.58ngL(-)(1), respectively. The variation in PAHs was higher in surface water. Cubic polynomial regressions using the sampling rate for five PRCs (Rs-PRC) provided estimated in situ sampling rates (Rs). The turbulent condition in the surface water was important in enhancing Rs; however, diffusion was relevant to the bottom water, which was less turbulent and showed decreasing Rs at high MW PAHs. The sum of the dissolved PAH concentrations estimated with the SPMDs (CSPMD) was 5.87 and 9.15ngL(-)(1) in the surface and bottom water samples, respectively. The surface and bottom water PAHs were derived from different sources.

Emerging organic contaminants in coastal waters: anthropogenic impact, environmental release and ecological risk.

This study provides a first estimate of the sources, distribution, and risk presented by emerging organic contaminants (EOCs) in coastal waters off southwestern Taiwan. Ten illicit drugs, seven nonsteroidal anti-inflammatory drugs (NSAIDs), five antibiotics, two blood lipid regulators, two antiepileptic drugs, two UV filters, caffeine, atenolol, and omeprazole were analyzed by solid-phase extraction and liquid chromatography coupled to tandem mass spectrometry (SPE-LC-MS/MS). Thirteen EOCs were detected in coastal waters, including four NSAIDs (acetaminophen, ibuprofen, ketoprofen, and codeine), three antibiotics (ampicillin, erythromycin, and cefalexin), three illicit drugs (ketamine, pseudoephedrine, and MDMA), caffeine, carbamazepine, and gemfibrozil. The median concentrations for the 13 EOCs ranged from 1.47 ng/L to 156 ng/L. Spatial variation in concentration of the 13 EOCs suggests discharge into coastal waters via ocean outfall pipes and rivers. Codeine and ampicillin have significant pollution risk quotients (RQ>1), indicating potentially high risk to aquatic organisms in coastal waters.

Air-water exchange fluxes of polycyclic aromatic hydrocarbons in the tropical coast, Taiwan.

Air-water exchange fluxes of polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in air and water samples from two sites on the Kenting coast, located at the southern tip of Taiwan, from January to December 2010. There was no significant difference in the total PAH (t-PAH) concentrations in both gas and dissolved phases between these two sites due to the less local input which also coincided to the low levels of t-PAH concentration; the gas and dissolved phases averaged 1.29±0.59 ng m(-3) and 2.17±1.19 ng L(-1) respectively. The direction and magnitude of the daily flux of PAHs were significantly influenced by wind speed and dissolved PAH concentrations. Individual PAH flux ranged from 627 ng m(-2) d(-1) volatilization of phenanthrene during the rainy season with storm-water discharges raising dissolved phase concentration, to 67 ng m(-2) d(-1) absorption of fluoranthene during high wind speed periods. Due to PAH annual fluxes through air-water exchange, Kenting seawater is a source of low molecular weight PAHs and a reservoir of high molecular weight PAHs. Estimated annual volatilization fluxes ranged from 7.3 µg m(-2) yr(-1) for pyrene to 50 µg m(-2) yr(-1) for phenanthrene and the absorption fluxes ranged from -2.6 µg m(-2) yr(-1) for chrysene to -3.5 µg m(-2) yr(-1) for fluoranthene.

Diffusive exchange of PAHs across the air-water interface of the Kaohsiung Harbor lagoon, Taiwan.

Instantaneous air-water polycyclic aromatic hydrocarbons (PAHs) exchange fluxes were calculated in 22 pairs of ambient air and water samples from Kaohsiung Harbor lagoon, from December 2003 to January 2005. The highest net volatilization (3135 ng m(-2) day(-1)) and absorptive (-1150 ng m(-2) day(-1)) fluxes in the present study were obtained for the three-ring PAH phenanthrene on 7 April and 27 January 2004, respectively. All PAH diffusive fluxes for three-ring PAHs except phenanthrene were mainly volatilization exchange across the air-water interface. Phenanthrene and the four-ring PAHs were absorbed primarily from the atmosphere and deposited to the surface water, although some minor volatilization fluxes were also observed. Differences in flux magnitude and direction between the dry and wet seasons were also evident for PAHs. Strong absorptive/weaker volatilization PAH fluxes occurred in the dry season, but the opposite was found in the wet season. The mean daily PAH diffusive fluxes were an in flux of -635 ng m(-2) day(-1) in the dry season and an efflux of 686 ng m(-2) day(-1) in the wet season. The integrated absorbed and emitted fluxes of PAHs for harbor lagoon surface waters in the dry and wet seasons were 3.1 kg and 3.4 kg, respectively. Different from water bodies located in temperate zone, phenanthrene diffusive fluxes in Kaohsiung Harbor lagoon was favored in volatilization from surface waters during the wet season (April to September) because of scavenging by precipitation and dilution by prevailing southwesterly winds. In addition, this study used both of salinity and temperature to improve estimation of Henry's law constants (H) of PAHs in a tropical coastal area and show that correction for salinity produced 13-15% of differences in H values.

Polybrominated diphenyl ethers and polychlorinated biphenyls in sediments of southwest Taiwan: regional characteristics and potential sources.

Very little information is available on the contamination of coastal sediments of Taiwan by PBDEs and PCBs. In this study, we determined the concentrations of 19 PBDE and 209 PCB congeners in 57 surface sediment samples to identify the possible sources of PBDEs and PCBs. The total PBDE and PCB concentrations ranged from below detection limit to 7.73 ng/g and 0.88-7.13 ng/g, respectively; these values are within the ranges observed for most coastal sediments worldwide. The PBDE congeners were dominated by BDE-209 (50.7-99.7%), with minor contributions from penta- and octa-BDEs. The signatures of PCB congeners suggested that PCB residues in Kaohsiung coast may be the legacy of past use or the result of ongoing inputs from the maintenance, repair and salvage of old ships. Principal component analysis of the congener-specific composition of PBDEs and PCBs revealed distinct regional patterns that are related to the use of commercial products.

Distribution and source differentiation of PAHs and PCBs among size and density fractions in contaminated harbor sediment particles and their implications in toxicological assessment.

Sediment samples collected from Kaohsiung Harbor (Taiwan) were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) and 118 individual polychlorinated biphenyl (PCB) congeners in various particle size fractions and two density fractions. The PAHs in the low density fraction were a much more sensitive and effective indicator of the PAH source than those in the sediment as a whole. Hierarchical cluster analysis of PAH analytes in the low density sediments revealed significant differences in compositional patterns between locations and among size fractions. In the sediment samples from both study sites, the low density fraction particles had up to 155 and 150 times higher concentrations of PAHs and PCBs, respectively, than those in the corresponding high density fractions. In addition, the total toxic benzo[a]pyrene and 2,3,7,8-tetrachlorodibenzodioxin (TCDD, dioxin) equivalents in the sediment low density fractions were much higher (up to 170 and 273 times, respectively) than the corresponding high density fractions.

A preliminary assessment of polycyclic aromatic hydrocarbon distribution in the kenting coral reef waters of southern Taiwan.

This distribution and variation of 45 polycyclic aromatic hydrocarbons (PAHs) in the waters of Kenting coral reefs were investigated by using sensitive research-grade sampling and analytical methods. The concentration levels of total PAHs (including particulate and dissolved PAHs) in the Kenting waters were relatively low, ranging from 2.2 to 34.4 ng/L. There was no significant spatial difference in PAH concentrations among the sampling stations, even between the surface and bottom waters. The fraction of dissolved PAHs on average was greater than that of particulate PAHs due to the small amount of total suspended particles. The partition coefficients between the particulate and dissolved phase (log K(oc)) were positively correlated with their log K(ow) values (r(2) = 0.67, n = 80), except for the more hydrophobic PAHs with log K(ow) values greater than 5.91. Results of principal component analysis indicate that the patterns of particulate PAH compositions were similar through the Kenting waters in the fall and winter, whereas there was a significant spatial difference between the spring and summer samples, which might be affected by a combination of land runoff and coastal currents. PAHs along the Kenting coasts were dominated by low-molecular PAHs, which have higher solubility than high-molecular PAHs. Based on isomer ratios, analysis of the source of PAHs in the Kenting coastal waters demonstrated that the PAHs come mostly from petroleum and, to a lesser degree, from combustion.

Polycyclic aromatic hydrocarbons in coastal sediments of southwest Taiwan: an appraisal of diagnostic ratios in source recognition.

Fifty-seven surface sediment samples were collected from the coast of southwest Taiwan and analyzed for polycyclic aromatic hydrocarbons (PAHs). Concentrations of total PAHs (28 PAH compounds) ranged from 15 to 907 ng g(-1) dry weight. Diagnostic ratios showed that PAHs in the sediments of the Gaoping estuary were predominantly of petroleum origin, whereas sediments from the Kaohsiung coast contained principally combustion-derived PAHs. Principal component analysis indicated that emissions from automobiles and coal burning were the main sources of combustion-derived PAHs. The relatively high ratios of perylene/penta-aromatic PAH isomers in sediments from the Tainan coast and some off-shore stations on the Kaohsiung coast suggest a significant diagenetic PAH contribution. The study shows that certain diagnostic ratios are useful and sensitive in delineating the distribution of PAHs from specific sources in southwest Taiwan. The phenanthrene/anthracene ratio is a better indicator than the methylphenanthrenes/phenanthrene ratio for tracing petrogenic PAHs, and the benzo(a)anthracene/chrysene and indeno(1,2,3-c,d)pyrene/benzo(g,h,i)perylene ratios are more specific than the benzo(a)pyrene/benzo(e)pyrene and benzo(b)fluoranthcene/benzo(k)fluoranthcene ratios in distinguishing PAHs from various pyrogenic sources.

Seasonality of diffusive exchange of polychlorinated biphenyls and hexachlorobenzene across the air-sea interface of Kaohsiung Harbor, Taiwan.

Gaseous and dissolved concentrations of polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) were measured in the ambient air and water of Kaohsiung Harbor lagoon, Taiwan, from December 2003 to January 2005. During the rainy season (April to September), gaseous PCB and HCB concentrations were low due to both scavenging by precipitation and dilution by prevailing southwesterly winds blown from the atmosphere of the South China Sea. In contrast, trace precipitation and prevailing northeasterly winds during the dry season (October to March) resulted in higher gaseous PCB and HCB concentrations. Instantaneous air-water exchange fluxes of PCB homologues and HCB were calculated from 22 pairs of air and water samples from Kaohsiung Harbor lagoon. All net fluxes of PCB homologues and HCB in this study are from water to air (net volatilization). The highest net volatile flux observed was +172 ng m(-)(2) day(-1) (dichlorobiphenyls) in December, 2003 due to the high wind speed and high dissolved concentration. The PCB homologues and HCB fluxes were significantly governed by dissolved concentrations in Kaohsiung Harbor lagoon. For low molecular weight PCBs (LMW PCBs), their fluxes were also significantly correlated with wind speed. The net PCB and HCB fluxes suggest that the annual sums of 69 PCBs and HCB measured in this study were mainly volatile (57.4 x 10(3) and 28.3 x 10(3) ng m(-2) yr(-1), respectively) and estimated yearly, 1.5 kg and 0.76 kg of PCBs and HCB were emitted from the harbor lagoon surface waters to the ambient atmosphere. The average tPCB flux in this study was about one-tenth of tPCB fluxes seen in New York Harbor and in the Delaware River, which are reported to be greatly impacted by PCBs.

Sources and distribution of polycyclic aromatic hydrocarbons in the sediments of Kaoping River and submarine canyon system, Taiwan.

In this study, we measured and analyzed polycyclic aromatic hydrocarbons (PAHs) in surface sediment samples collected from the Kaoping river and submarine canyon (KPSC) system to determine the compositional patterns and characteristic distributions of PAH and to elucidate the transport and fate of these land-derived particles. Concentrations of total PAH (sum of 28 PAH compounds) ranged from 22.6 to 45,100 ngg(-1) dry weight (dw) and the highest concentrations were found in the sediments of Donggang Harbor. The ratio of perylene to sum of penta-aromatic PAH isomers (47-55%) was higher in off-shore stations, suggesting a diagenetic PAH source. Various isomeric ratios also indicated that combustion was a significant source of PAH to the sediment at stations located along the Kaoping river and the north-western shelf of the Kaoping estuary. However, in the south-eastern shelf and some canyon sites, petroleum-derived PAHs were a more significant source of these compounds. Principal component analysis and hierarchical cluster analysis suggest PAHs in the sediments from the north-western shelf, and river and canyon sediments might be a pyrogenic product of coal and diesel-burning vehicles, while those of the south-eastern shelf may be petrogenic. PAH concentrations and compositional patterns are effective tracers of particulate transport in KPSC system. The seaward transport of riverine particulates was found to be mostly directed to NW-shelf and/or canyon.

Composition and distribution of polycyclic aromatic hydrocarbons in the surface sediments from the Susquehanna River.

Polycyclic aromatic hydrocarbon (PAH) concentrations in 34 surface sediments along the Susquehanna River were investigated in 2000. The total concentrations of PAHs in the surface sediments of Lake Clarke, Lake Aldred, the upper Conowingo Reservoir, and the lower Conowingo Reservoir were 3.3+/-1.5 microg g-1 (n=9), 1.6+/-1.3 microg g-1 (n=4), 9.8+/-5.5 microg g-1 (n=7), and 4.0+/-1.2 microg g-1 (n=14), respectively. These represent the first comprehensive measurement of PAHs in Susquehanna River surface sediments. Overall, total PAH concentrations were relatively lower in Lake Aldred, which is more shallow and sloped, and significantly higher in the upper Conowingo Reservoir. The sediment PAH levels were related to river flow rates, which are indirectly correlated with the particle size of the surface sediments. Total PAH levels in all the studied sites were below the effects range median (ERM) of 44.8 microg g-1 with 38% (13 of the 34 sampling sites) exceeding the effects range low (ERL) of 4.02 microg g-1. Principal component analysis indicated that variations in the PAH compound patterns of each reservoir decreased from upstream to downstream, indicating that the surface sediments were mixed along the Susquehanna River. The PAH patterns in the lower Conowingo Reservoir sediments were a combination of those upstream sources. Source analysis using isomer ratios as indicators suggested that PAHs in the Susquehanna River surface sediment are derived from the combustion of fossil fuels such as coal and gasoline with coal as the major source of contaminants.