Polycyclic Aromatic Hydrocarbons In River Research Articles

Systematic underestimation of polycyclic aromatic hydrocarbon aqueous concentrations in rivers

Polycyclic aromatic hydrocarbons (PAHs) are a widespread group of organic contaminants whose presence in water bodies is cause of severe concern. With few exceptions, the majority of PAHs is hydrophobic, presents a high adsorption affinity, and is thus primarily transported within river systems during high-flow events together with suspended particulate matter (SPM). Evidence exists of analytical challenges related to the incomplete extraction of PAHs adsorbed to solids and thus to a potential negative bias in the chemical analysis of PAHs in bulk water samples with high SPM content. Despite this, partly due to the elevated efforts required to collect representative samples containing sufficient SPM for the separate PAH analysis in this matrix, several investigations rely on the analysis of aqueous samples. This study tests the hypothesis that surveys based exclusively on bulk water may lead to a systematic underestimation of the real contamination level and transport of PAHs in rivers. Six high-turbidity events were examined in three Austrian rivers applying time-integrated sampling and simultaneously analyzing PAHs in total bulk water, filtered water, SPM, and supernatant. Despite an unavoidable degree of uncertainty in such challenging sampling scheme, the results indicate that measurements performed with best available standard methods in bulk water samples determined in average only about 40% of the theoretically expected total PAHs concentrations derived from the analyses in SPM. Such deviation has important implications for the reliable assessment of the compliance with environmental quality standards as well as for surveys aimed to estimate riverine loads, validate emission models, and understand the transport dynamics of PAHs in rivers. Whereas the first objective, e.g., in European countries, is alternatively achieved via monitoring in biota, the latter ones require efforts directed to complement monitoring campaigns with separate sampling of SPM, with monitoring of suspended solids transport to appropriately select and interpret the results of water samples and to improve the chemical analysis of PAHs in bulk water samples with high solids content.

Polycyclic aromatic hydrocarbons in rivers and health risk consequences of human exposure: a Nigerian case study

Polycyclic aromatic hydrocarbons in rivers and health risk consequences of human exposure: a Nigerian case study

Contamination characteristics of polycyclic aromatic hydrocarbons in river and coastal sediments collected from the multi-industrial city of Ulsan, South Korea

River and coastal sediments were collected at 17 stations in Ulsan, the largest industrial city in South Korea, to evaluate the levels, profiles, emission sources, and spatial distribution of polycyclic aromatic hydrocarbons (PAHs). The mean concentration of Σ16 PAHs was 722 ng/g, and fluoranthene was a predominant compound. PAHs with 4–6 rings showed higher proportions than PAHs with 2–3 rings. The stations located near industrial complexes showed elevated levels of indicator compounds for petroleum, coal, coke, and fuel combustion. Therefore, petrochemical industries, coal pier, non-ferrous industries, and vehicles were identified as the emission sources. As industrialization and urbanization progressed, an increase in PAH levels and profile changes were observed as a result of the increasing industrial fuel consumption and the increasing number of vehicles. This is the first study that confirmed the change of PAHs in sediment caused by the change of emission sources over time in Ulsan.

Study on the Spatial and Temporal Distribution and Risk Assessment of PAHs between River and Groundwater - Take the Typical Section of Beijing North Canal as an Example

Pan, Z.H.; Li, B.H.; Yang, J.; Zhang, D.S.; Yang, Y., and Zhang, S.W., 2020. Study on the spatial and temporal distribution and risk assessment of PAHs between river and groundwater - Take the typical section of Beijing north canal as an example. In: Bai, X. and Zhou, H. (eds.), Advances in Water Resources, Environmental Protection, and Sustainable Development. Journal of Coastal Research, Special Issue No. 115, pp. 361-366. Coconut Creek (Florida), ISSN 0749-0208.Understanding the interaction of polycyclic aromatic hydrocarbons (PAHs) in river and groundwater is of great significance to the prevention and control of their pollution and to the protection of water resources. In order to study the interaction of PAHs in rivers and groundwater of different aquifers in Beiyun River Basin, here water samples were collected from rivers and groundwater in different periods, and the composition, content, temporal and spatial distribution characteristics of PAHs in rivers and groundwater were analyzed by correlation and difference analysis method. In addition, risk assessment was done by using risk entropy method. The results showed that the detection rate of 16 kinds of PAHs were about 100%, except benzo [a] pyrene and dibenzo [a, H] anthracene. Naphthalene was the main component, which was 1587.42ng/l, accounting for 85.6% of the total amount. In spring, the concentrations of PAHs were significantly lower than those in summer, and the concentration of 2-3-PAHs was higher than that of 4-PAHs. In general, the concentration of PAHs in the phreatic aquifer of the downstream reaches in the Beiyun River was higher than that in the upper reaches. According to the risk assessment data, the ecological risk of the study area was relatively low in different seasons and geographical conditions.

Distribution, Sources, and Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Tributary Waters of the Lower Reaches of the Yangtze River, China

The lower reaches of the Yangtze River are a typical gathering place of chemical industrial parks in China. Polycyclic aromatic hydrocarbons (PAHs) emitted in the production process of chemical enterprises enter the tributary water body through atmospheric deposition and surface runoff, and finally merge into the Yangtze River. In this study, the distribution characteristics, source analysis, and ecological risk assessment of PAHs in a series of typical water samples collected in the tributary waters of the Yangtze River were studied. PAH monomers in the samples were mainly low-ring. The total concentration of PAHs was in the range of 37.27 to 285.88 ng·L-1 with a mean value of 78.31 ng·L-1, while the monomer concentration of PAHs ranged from 0 to 61.35 ng·L-1. The lowest detection rate was benzo[k] fluoranthene and benzo[a] pyrene at 75%. As a toxic PAH monomer, the concentration of benzo[a] pyrene ranged from 0 to 11.08 ng·L-1. According to "Water Quality Standards for Drinking Water Sources (CJ 3020-1993)" of China, the concentration of benzo[a] pyrene in a water sample (S12) located near Wuxi City exceeded the limit of drinking water standards (10 ng·L-1). Compared with the total concentration of PAHs in rivers in some typical regions of the world, the concentration of PAHs in this study was generally at low to moderate levels. According to the source analysis results of the ratio method and principal component analysis, the concentration of PAHs in water was mainly affected by fossil combustion, automobile exhaust, and chemical emissions. To assess the potential ecosystem risk of PAHs in the investigated area, the risk quotient (RQ) was used. In addition to the DBA monomer, the relative quantities (RQs) (replication) of the remaining monomers were greater than 1, and the RQ (MPCs) values in all the monomers were less than 1, indicating that the ecological risk of water samples was at a medium level. From the perspective of long-term environmental exposure, appropriate control measures should be considered to prevent further pollution. The results can provide reference for PAH risk assessment and pollution control of chemical industrial parks in the lower reaches of the Yangtze River.

Rational integration of porous organic polymer and multiwall carbon nanotube for the microextraction of polycyclic aromatic hydrocarbons.

By integration of benzene-constructed porous organic polymer (KBF) and multiwalled carbon nanotube (MWCNT), a MWCNT-KBF hybrid material was constructed through in situ knitting benzene with formaldehyde dimethyl acetal inthe presence of MWCNTs to form anetwork. MWCNT-KBF was then adopted as a novel solid-phase microextraction (SPME) fiber coating. Coupled togas chromatography-flame ionization detection, the MWCNT-KBF-assisted SPME method showed large enhancement factors (483-2066), low limits of detection (0.04-0.12μgL-1), good linearity (0.13-50μgL-1), and acceptable reproducibility (4.2-10.2%) for the determination of polycyclic aromatic hydrocarbons (PAHs). The method recoveries of seven PAHs were in the range 80.1-116.3%, with relative standard deviations (RSDs) ranging from 3.5 to 11.9%. The SPME method was successfully applied to the determination of PAHs in river, pond, rain, and waste water, providing a good alternative for monitoring trace level of PAHs in environmental water. Graphical abstract Schematic representation of the rational integration of porous organic polymer (KBF) and multiwalled carbon nanotube (MWCNT) to form a MWCNT-KBF hybrid material through in situ knitting benzene with formaldehyde dimethyl acetal at the presence of MWCNT.

Simple and effective dispersive micro-solid phase extraction procedure for simultaneous determination of polycyclic aromatic compounds in fresh and marine waters

In this work, we developed a simple, comprehensive, and effective device and procedure for sample preparation based on dispersive micro-solid phase extraction (d-μ-SPE) for the simultaneous determination of 30 polycyclic aromatic compounds or PACs (including 16 polycyclic aromatic hydrocarbons (PAHs), 3 quinones, and 11 nitro-PAHs) in water samples. The extraction/preconcentration step was carried out in a customized glass device (20–250 mL) using C18 as the sorbent. A mini-UniPrep syringeless filter was used as a desorption device, which allowed one-step desorption, filtration, and injection. The main factors affecting the d-μ-SPE were optimized using the Doehlert design. The optimal d-μ-SPE conditions were 100 mg of C18, 32 min of extraction at 1000 rpm, and 20 min of sonication (at the desorption step). The limit of detection (LOD) for PAHs and nitro-PAHs ranged from 0.8 ng L−1 (phenanthrene) to 1.5 ng L−1 (indene [1,2,3-cd]pyrene) and from 300 ng L−1 (2-nitrofluorene) to 500 ng L−1 (2-nitrobiphenyl), respectively. For quinones, it varied from 1.12 μg L−1 (1,4-naphthoquinone) to 1.70 μg L−1(9,10-phenanthrenequinone). Relative recoveries ranged from 59.1% (benzo[a]pyrene) to 110% (chrysene) for most PAHs and 68.9% (2-nitrofluorene) to 124% (1-methyl-6-nitronaphthalene) for the nitro-PAHs. The recoveries for quinones ranged from 65.3% (9,10-phenanthrenequinone) to 95.3% (9,10-anthraquinone). The enrichment factor varied from 213 (Nap) to 497 (Flu), from 39 (1,4-naphthoquinone) to 254 (9,10-anthraquinone), and from 122 (2-nitrobiphenyl) to 295 (1-methyl-4-nitronaphthalene) for the PAHs, nitro-PAHs, and quinones, respectively. After validation, the procedure was successfully applied toward the determination of PACs in river and marine water samples. Low-molecular-weight PAHs were detected with high frequencies (62.5–100%) and the total PAH concentration ranged from 2.30 ng L−1 (benzo[a]pyrene) to 1070 ng L−1 (pyrene). Quinones were found at concentrations ranging from below the LOD to up to 19.8 μg L−1. The proposed procedure was thus found to be comprehensive, precise, accurate, and suitable for determination of PACs in water samples.

Turnover and legacy of sediment-associated PAH in a baseflow-dominated river

Polycyclic Aromatic Hydrocarbons (PAH) ubiquitously occur in rivers and threaten the aquatic ecosystem. Understanding their fate and behaviour in rivers can help in improving management strategies. We develop a particle-facilitated transport model considering suspended sediments with sorbed PAH from different origins to investigate the turnover and legacy of sediment-bound PAH in the baseflow-dominated Ammer River in southwest Germany. Our model identifies the contributions of dissolved and particle-bound PAH during wet and dry periods to the annual load. The analysis of in-stream processes enables investigating the average turnover times of sediments and attached PAH for the main stem of the river. The legacy of sediment-bound PAH is studied by running the model assuming a 50% reduction in PAH emissions after the introduction of environmental regulation in the 1970s. Our results show that sediment-bound and dissolved PAH account for 75% and 25% of the annual PAH load, respectively. PAH are mainly emitted from urban areas that contribute over 74% to the total load. In steep reaches, the turnover times of sediments and attached PAH are similar, whereas they differ by 1–2 orders of magnitude in reaches with very mild slopes. Flow rates significantly affect PAH fluxes between the mobile water and the riverbed over the entire river. Total PAH fluxes from the river bed to the mobile water are simulated to occur when the discharge is larger than 5 m3s −1. River segments with large sediment storage show a potential of PAH legacy, which may have caused a PAH release over 10–20 years after the implementation of environmental regulation. This study is useful for assessing environmental impacts of PAH in rivers (e.g., their contribution to the river-water toxicity) and exemplifies that the longitudinal distribution, turnover, and legacy potential of PAH in a river system require a mechanistic understanding of river hydraulics and sediment transport.

MXene/reduced graphene oxide hydrogel film extraction combined with gas chromatography–tandem mass spectrometry for the determination of 16 polycyclic aromatic hydrocarbons in river and tap water

In this study, MXene/reduced graphene oxide (MXene/rGO) hydrogel film, a novel nanomaterial was prepared and used as adsorbent for extraction of 16 polycyclic aromatic hydrocarbons (PAHs) in river and tap water prior to gas chromatography–tandem mass spectrometric analysis (GC–MS/MS). The properties of MXene/rGO hydrogel film were characterized by scanning electron microscope (SEM) and X-ray diffractometer (XRD). The PAHs in water samples were enriched with MXene/rGO, then eluted with n-hexane, finally separated with HP-5MS column (30 m × 0.32 mm, 0.25 μm), and finally detected by mass spectrometer with SIM mode. The method had linear ranges of 0.005–2.00 μg/L with the correlation coefficients greater than 0.995. The recoveries of the method ranged from 80.3% to 109.9%, with the relative standard deviations (RSDs) less than 10.01%. The limits of detection (LODs) were less than 0.005 μg/L. The method is simple, sensitive, precise, accurate, environmentally-friendly and it has been successfully applied to the determination of 16 PAHs in river and tap water samples.

Determination of Dissolved Concentrations of Polycyclic Aromatic Hydrocarbons in River

This study shows the sensitivity of using silicone rubber passive sampler(SR-PS) andgas chromatography with mass spectrometer (GC-MS) detection for monitoring and identification of polycyclic aromatic hydrocarbons in surface water systems. The analysis was performed for eighteen PAHs compounds after pre-concentration using Soxhlet extraction method. By comparison, a total of 13 PAHs were detected in the spot water samples, of which none was quantifiable. The freely dissolved PAH concentrations were found to range from 0.17 ng/L to 0.76 ng/L at Ugieriver. The use of fluorine d10 as Performance reference compound(PRC) gives a sampling rates of 8.14 (L/day) for silicone rubber passive samplers. Analysis of PAHs concentrations suggest the contaminants are mainly from pyrolytic sources. Overall it can be concluded that SR-PS are viable alternatives in the environmental monitoring of PAHs.

Determination of Dissolved Concentrations of Polycyclic Aromatic Hydrocarbons in River

This study shows the sensitivity of using silicone rubber passive sampler(SR-PS) andgas chromatography with mass spectrometer (GC-MS) detection for monitoring and identification of polycyclic aromatic hydrocarbons in surface water systems. The analysis was performed for eighteen PAHs compounds after pre-concentration using Soxhlet extraction method. By comparison, a total of 13 PAHs were detected in the spot water samples, of which none was quantifiable. The freely dissolved PAH concentrations were found to range from 0.17 ng/L to 0.76 ng/L at Ugieriver. The use of fluorine d10 as Performance reference compound(PRC) gives a sampling rates of 8.14 (L/day) for silicone rubber passive samplers. Analysis of PAHs concentrations suggest the contaminants are mainly from pyrolytic sources. Overall it can be concluded that SR-PS are viable alternatives in the environmental monitoring of PAHs.

Polydimethylsiloxane/metal-organic frameworks coated fiber for solid-phase microextraction of polycyclic aromatic hydrocarbons in river and lake water samples

In this study, polydimethylsiloxane/metal-organic frameworks (PDMS/MOFs), including PDMS/MIL-101 and PDMS/MOF-199, were immobilized onto a stainless steel wire through sol–gel technique as solid-phase microextraction (SPME) fiber coating. The prepared fibers were used for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from water samples prior to gas chromatography–mass spectrometry (GC–MS) analysis. Under the optimized experiment conditions, the PDMS/MIL-101 coated fiber exhibited higher extraction efficiency towards PAHs than that of PDMS/MOF-199. Several parameters affecting the extraction of PAHs by SPME with PDMS/MIL-101 fiber, including the extraction temperature, extraction time, sample volume, salt addition and desorption conditions, were investigated. The limits of detection (LODs) were less than 4.0ngL−1 and the linearity was observed in the range from 0.01 to 2.0µgL−1 with the correlation coefficients (r) ranging from 0.9940 to 0.9986. The recoveries of the method for the PAHs from water samples at spiking levels of 0.05 and 0.2µgL−1 ranged from 78.2% to 110.3%. Single fiber repeatability and fiber-to-fiber reproducibility were less than 9.3% and 13.8%, respectively.

Determination and distribution of polycyclic aromatic hydrocarbons in rivers, surface runoff, and sediments in and around Thohoyandou, Limpopo Province, South Africa

Water quality in rural areas is affected adversely by build-up of traffic-generated organic compounds on road surfaces, leading to their presence in water runoff and sediments. Characterising these compounds is a first step in developing measures for the removal of such pollutants from water courses. In this study, liquid-liquid extraction of water samples from several rivers and surface run-off enabled quantification of major PAHs. Soxhlet extraction of sediment samples was followed by clean-up of samples using column chromatography. The PAHs were quantified by gas chromatography. In water and sediment samples, 6 PAHs were identified and quantified. In river water samples, individual PAH levels ranged between 0.1 µg/. and 137 µg/., while in sediment samples levels ranged between 17.9 µg/kg and 9870 µg/kg. For surface run-off, levels ranged between 0.6 µg/. and 2 500 µg/. for water samples and between 112 µg/kg and 34 400 µg/kg for sediment samples. Total levels of PAHs in sediment samples were relatively high (111.6 to 61 764 µg/kg) compared to those in water from both river and surface run-off (29.2 to 3 064.8 µg/.), and PAH levels in surface runoff were much higher than in river waters, implicating tarred roads and parking lots as main point sources of PAHs. PAH ratios also indicate that the PAH content of runoff and sediment is more likely due to pyrogenic sources, i.e. vehicle emissions, although petrogenic sources (mainly oil spills) also play an important role. Toxic Equivalence Quotient (TEQ) values in river and runoff waters ranged from 0.10 to 4.03 µg/. and for sediments the TEQ ranged from 0.50 to 272.23 µg/kg. These results are of concern, as the calculated TEQ is likely to be an underestimate of the actual TEQ, since only 6 PAHs with relatively low toxicities were analysed. Long droughts and low rainfall, and washing of automobiles in and near the rivers are important factors which may have contributed to the observed levels of PAHs in both river water and sediments.Keywords: Polycyclic aromatic hydrocarbon, river water, runoff, sediment

Polymeric ionic liquid bucky gels as sorbent coatings for solid-phase microextraction

Novel cross-linked polymeric ionic liquid (PIL) bucky gels were formed by free-radical polymerization of polymerizable ionic liquids gelled with multi-walled carbon nanotubes (MWCNT) and used as sorbent coatings for solid-phase microextraction (SPME). The combination of PIL with MWCNTs significantly enhanced the π–π interaction between the sorbent coatings and the aromatic analytes. Compared to the neat PIL-based sorbent coating, the PIL bucky gel sorbent coatings demonstrated higher extraction efficiency for the extraction of polycyclic aromatic hydrocarbons (PAHs). A partitioning extraction mechanism was observed for the PIL/MWCNT-based sorbent coatings indicating that the addition of MWCNTs did not seem to affect the extraction mechanism of the sorbent coating. The analyte-to-coating partition coefficients (logKfs) were estimated and the limits of detection (LOD) for selected PIL bucky gel sorbent coating were determined to be in the range of 1–2.5ngL−1. Recovery studies were also performed for PAHs in river and tap water to validate the applicability of the developed method.

Oxygenated, nitrated, methyl and parent polycyclic aromatic hydrocarbons in rivers of Haihe River System, China: Occurrence, possible formation, and source and fate in a water-shortage area

Substituted polycyclic aromatic hydrocarbons (SPAHs) occur ubiquitously in the whole global environment as a result of their persistence and widely-spread sources. Some SPAHs show higher toxicities and levels than the corresponding PAHs. Three types of most frequently existing SPAHs, oxygenated-PAHs (OPAHs), nitrated-PAHs (NPAHs), and methyl-PAHs (MPAHs), as well as the 16 priority PAHs were investigated in this study. The purpose was to identify the occurrence, possible transformation, and source and fate of these target compounds in a water shortage area of North China. We took a river system in the water-shortage area in China, the Haihe River System (HRS), as a typical case. The rivers are used for irrigating the farmland in the North of China, which probably introduce these pollutants to the farmland of this area. The MPAHs (0.02–0.40μg/L in dissolved phase; 0.32–16.54μg/g in particulate phase), OPAHs (0.06–0.19μg/L; 0.41–17.98μg/g), and PAHs (0.16–1.20μg/L; 1.56–79.38μg/g) were found in the water samples, but no NPAHs were detected. The concentrations of OPAHs were higher than that of the corresponding PAHs. Seasonal comparison results indicated that the OPAHs, such as anthraquinone and 2-methylanthraquinone, were possibly transformed from the PAHs, particularly at higher temperature. Wastewater treatment plant (WWTP) effluent was deemed to be the major source for the MPAHs (contributing 62.3% and 87.6% to the receiving river in the two seasons), PAHs (68.5% and 89.4%), and especially OPAHs (80.3% and 93.2%) in the rivers. Additionally, the majority of MPAHs (12.4kg, 80.0% of the total input), OPAHs (16.2kg, 83.5%), and PAHs (65.9kg, 93.3%) in the studied months entered the farmland through irrigation.

Concentration Levels and Potential Ecological Risks of Polycyclic Aromatic Hydrocarbons in Chinese Rivers

Polycyclic aromatic hydrocarbons (PAHs) are one of the most important persistent organic pollutants (POPs) and are widespread in surface waters in China. Based on the literature surveyed, concentration levels and geographic distribution of 16 PAHs in major Chinese rivers were summarized. The results showed that 2-3-ring PAHs were predominated in water, 4-ring PAHs were abundant in suspended particular matter (SPM), and 3-6 ring PAHs were the main chemical forms in sediment. In general, concentration levels of PAHs in rivers from northern China were higher than those from southern China. There existed a significant difference between concentration level of PAHs from the north and from the south. In comparison with concentration levels of PAHs in the world rivers, level of PAHs in dissolved phase in Chinese rivers was higher than those from other countries, while PAHs concentration in SPM and sediment of Chinese rivers was in the middle range. The quotient method was used to screen the potential risk of PAHs to aquatic organisms. It appeared that 7 among 16 PAHs, i.e., phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene and benzo[a]pyrene, might have potential adverse effects to aquatic system, which should be particularly concerned.

Novel approach to microwave-assisted extraction and micro-solid-phase extraction from soil using graphite fibers as sorbent

A single-step extraction–cleanup procedure involving microwave-assisted extraction (MAE) and micro-solid-phase extraction (μ-SPE) has been developed for the analysis of polycyclic aromatic hydrocarbons (PAHs) from soil samples. μ-SPE is a relatively new extraction procedure that makes use of a sorbent enclosed within a sealed polypropylene membrane envelope. In the present work, for the first time, graphite fiber was used as a sorbent material for extraction. MAE–μ-SPE was used to cleanup sediment samples and to extract and preconcentrate five PAHs in sediment samples prepared as slurries with addition of water. The best extraction conditions comprised of microwave heating at 50 °C for a duration of 20 min, and an elution (desorption) time of 5 min using acetonitrile with sonication. Using gas chromatography (GC)–flame ionization detection (FID), the limits of detection (LODs) of the PAHs ranged between 2.2 and 3.6 ng/g. With GC–mass spectrometry (MS), LODs were between 0.0017 and 0.0057 ng/g. The linear ranges were between 0.1 and 50 or 100 μg/g for GC–FID analysis, and 1 and 500 or 1000 ng/g for GC–MS analysis. Granular activated carbon was also used for the μ-SPE device but was found to be not as efficient in the PAH extraction. The MAE–μ-SPE method was successfully used for the extraction of PAHs in river and marine sediments, demonstrating its applicability to real environmental solid matrixes.

Partitioning and source diagnostics of polycyclic aromatic hydrocarbons in rivers in Tianjin, China

Water, suspended particulate matter (SPM), and sediment samples were collected from ten rivers in Tianjin and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), dissolved organic carbon (DOC), particulate organic carbon (POC) in SPM and total organic carbon (TOC) in sediment. The behavior and fate of PAHs influenced by these parameters were examined. Generally, organic carbon was the primary factor controlling the behavior of the 16 PAH species. Partitioning of PAHs between SPM and water phase was studied, and K OC for some PAH species were found to be significantly higher than the predicted values. The source of PAHs contamination was diagnosed by using PAH isomer ratios. Coal combustion was identified to be a long-term and prevailing contamination source for sediment, while sewage/wastewater source could reasonably explain a short-term PAHs contamination of SPM.

Binding of natural humic matter to polycyclic aromatic hydrocarbons in rivers of the Southeastern United States

The binding constants (Koc) of four polycyclic aromatic hydrocarbons (PAH) were determined for sedimentary fulvic and humic acids and the dissolved organic carbon (DOC) of five rivers in Georgia, USA. The log Koc for the PAH ranged: anthracene, 4.63-5.57; phenanthrene, 4.58-5.62; pyrene, 4.90-5.65; benzo(a)pyrene, 3.48-5.20. Log Koc values for the PAH compounds with riverine DOC were very similar for all rivers and more closely resembled those of sedimentary humic acids than the fulvic acids. The molecular size distribution of the riverine DOC indicates that >75% of the DOC occurs in size fractions >10,000 daltons. Despite similarities in Koc, there appear to be inter-river differences in the distribution of PAH among molecular size classes of the DOC, which have ramifications for water quality both in rivers and estuaries.