Occurrence and distribution of polycyclic aromatic hydrocarbons in surface water of the Raba River, Hungary

Temporal and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in the Danube River in Hungary

The Danube is a significant transboundary river on a global scale, with several tributaries. The effluents from industrial operations and wastewater treatment plants have an impact on the river's aquatic ecosystem. These discharges provide a significant threat to aquatic life by deteriorating the quality of water and sediment. Hence, a total of 16 Polycyclic Aromatic Hydrocarbons (PAHs) compounds were analyzed at six locations along the river, covering a period of 12 months. The objective was to explore the temporal and spatial fluctuations of these chemicals in both water and sediment. The study revealed a significant fluctuation in the concentration of PAHs in water throughout the year, with levels ranging from 224.8 ng/L during the summer to 365.8 ng/L during the winter. Similarly, the concentration of PAHs in sediment samples varied from 316.7 ng/g in dry weight during the summer to 422.9 ng/g in dry weight during the winter. According to the Europe Drinking Water Directive, the levels of PAHs exceeded the permitted limit of 100 ng/L, resulting in a 124.8% rise in summer and a 265.8% increase in winter. The results suggest that the potential human-caused sources of PAHs were mostly derived from pyrolytic and pyrogenic processes, with pyrogenic sources being more dominant. Assessment of sediment quality standards (SQGs) showed that the levels of PAHs in sediments were below the Effect Range Low (ERL), except for acenaphthylene (Acy) and fluorene (Fl) concentrations. This suggests that there could be occasional biological consequences. The cumulative Individual Lifetime Cancer Risk (ILCR) exceeds 1/104 for both adults and children in all sites.

Polycyclic Aromatic Hydrocarbons: Occurrence, Electroanalysis, Challenges, and Future Outlooks

The past several decades have seen increasing concern regarding the wide distribution of polycyclic aromatic hydrocarbons (PAHs) in environmental matrices. Primary toxicological data show PAHs' persistent characteristics and possible toxicity effects. Because of this pressing global issue, electroanalytical methods have been introduced. These methods are effective for PAH determination in environmental waters, even outclassing sophisticated analytical techniques such as chromatography, conventional spectrophotometry, fluorescence, and capillary electrophoresis. Herein, the literature published on PAHs is reviewed and discussed with special regard to PAH occurrence. Moreover, the recent developments in electrochemical sensors for PAH determination and the challenges and future outlooks in this field, are also presented.

Priority substances and emerging pollutants in urban rivers in Ukraine: Occurrence, fluxes and loading to transboundary European Union watersheds

The occurrence and fluxes of 18 priority substances and emerging pollutants listed in the European Union Water Framework Directive and a Watch List (trace metals (Cd, Pb and Ni), nonylphenols, octylphenols, 8 polyaromatic hydrocarbons, 4 dioxin-like polychlorinated biphenyls and diclofenac) were investigated in a Ukrainian city and the mass discharge loads of these compounds into EU-transboundary watersheds were estimated. Fluxes of chemicals were calculated per capita and per area of the Ukrainian urban territory and used to estimate mass loading of priority and emerging concern compounds from Lviv, Uzhorod and Chernivtsi (West Ukraine) to neighbouring EU-transboundary rivers. The highest loading was found for trace metals (1.15 t a^-1), diclofenac (0.7 t a^-1) and nonylphenols (0.4 t a^-1). Transboundary water contamination must be considered in order to successfully manage water resources in a manner that fulfils the requirements of EU environmental quality standards.

A review on environmental monitoring of water organic pollutants identified by EU guidelines

The contamination of fresh water is a global concern. The huge impact of natural and anthropogenic organic substances that are constantly released into the environment, demands a better knowledge of the chemical status of Earth's surface water. Water quality monitoring studies have been performed targeting different substances and/or classes of substances, in different regions of the world, using different types of sampling strategies and campaigns. This review article aims to gather the available dispersed information regarding the occurrence of priority substances (PSs) and contaminants of emerging concern (CECs) that must be monitored in Europe in surface water, according to the European Union Directive 2013/39/EU and the Watch List of Decision 2015/495/EU, respectively. Other specific organic pollutants not considered in these EU documents as substances of high concern, but with reported elevated frequency of detection at high concentrations, are also discussed. The search comprised worldwide publications from 2012, considering at least one of the following criteria: 4 sampling campaigns per year, wet and dry seasons, temporal and/or spatial monitoring of surface (river, estuarine, lake and/or coastal waters) and ground waters. The highest concentrations were found for: (i) the PSs atrazine, alachlor, trifluralin, heptachlor, hexachlorocyclohexane, polycyclic aromatic hydrocarbons and di(2-ethylhexyl)phthalate; (ii) the CECs azithromycin, clarithromycin, erythromycin, diclofenac, 17α-ethinylestradiol, imidacloprid and 2-ethylhexyl 4-methoxycinnamate; and (iii) other unregulated organic compounds (caffeine, naproxen, metolachlor, estriol, dimethoate, terbuthylazine, acetaminophen, ibuprofen, trimethoprim, ciprofloxacin, ketoprofen, atenolol, Bisphenol A, metoprolol, carbofuran, malathion, sulfamethoxazole, carbamazepine and ofloxacin). Most frequent substances as well as those found at highest concentrations in different seasons and regions, together with available risk assessment data, may be useful to identify possible future PS candidates.

Surface water polycyclic aromatic hydrocarbons (PAH) in urban areas of Nanjing, China

The concentration, sources and environmental risks of polycyclic aromatic hydrocarbons (PAHs) in surface water in urban areas of Nanjing were investigated. The range of ∑₁₆PAHs concentration is between 4,076 and 29,455 ng/L, with a mean of 17,212 ng/L. The composition of PAHs indicated that 2- and 3-ring PAHs have the highest proportion in all PAHs, while the 5- and 6-ring PAHs were the least in proportion. By diagnostic ratio analysis, combustion and petroleum were a mixture input that contributed to the water PAH in urban areas of Nanjing. Positive matrix factorization quantitatively identified four factors, including coke oven, coal combustion, oil source, and vehicle emission, as the main sources. Toxic equivalency factors of BaP (BaP_eq) evaluate the environmental risks of PAHs and indicate the PAH concentration in surface water in urban areas of Nanjing had been polluted and might cause potential environmental risks. Therefore, the PAH contamination in surface water in urban areas of Nanjing should draw considerable attention.

PAHs behavior in surface water and groundwater of the Yellow River estuary: Evidence from isotopes and hydrochemistry

Large-scale irrigation projects have impacted the regional surface-groundwater interactions in the North China Plain (NCP). Given this concern, the aim of this study is to evaluate levels of PAH pollution, identify the sources of the PAHs, analyze the influence of surface-groundwater interactions on PAH distribution, and propose urgent management strategies for PAHs in China's agricultural areas. PAH concentrations, hydrochemical indicators and stable isotopic compositions (δ¹⁸O and δ²H) were determined for surface water (SW) and groundwater (GW) samples. PAHs concentrations in surface water and groundwater varied from 11.84 to 393.12 ng/L and 8.51-402.84 ng/L, respectively, indicating mild pollution. The seasonal variations showed the following trend: PAHs in surface water at the low-water phase > PAHs in groundwater at the low-water phase > PAHs in surface water at the high-water phase > PAHs in groundwater at the high-water phase. Hydrochemical and δ¹⁸O value of most groundwater samples distributed between the Yellow River and seawater. The mean value of mixture ratio of the Yellow River water recharge to the groundwater was 65%, few anomalous sites can reach to 90%. Surface-groundwater interactions influence the spatial distribution of PAHs in the study area. In light of the ongoing serious pollution, management practices for source control, improved control technologies, and the construction of a monitoring network to warn of increased risk are urgently needed.

Polycyclic aromatic hydrocarbons (PAHs) in seawater and sediments from the northern Liaodong Bay, China

Levels, sources, and potential ecological risks of polycyclic aromatic hydrocarbons (PAHs) in surface seawater and sediments from the northern Liaodong Bay of China were seasonally investigated. Total concentrations of 16 PAHs varied from 145.96ng/L to 896.58ng/L in seawater, and from 191.99ng/g to 624.44ng/g in sediments. PAH concentrations in seawater differed significantly, whereas those in sediments exhibited a relatively stable pattern across seasons. PAHs with low molecular weight were predominant in seawater, but PAHs with high molecular weight were abundant in sediments. Crop straw and coal combustion were the main PAH pollution sources. The current levels of PAHs in the northern Liaodong Bay are relatively moderate compared with those in other bays and estuaries. Sediment from all sampling sites is characterized by low to medium ecotoxicological risk. No highly negative toxic effect could occur on the organisms and ecosystems in the northern Liaodong Bay.

Photochemical degradation of PAHs in estuarine surface water: effects of DOM, salinity, and suspended particulate matter

The photodegradation of several polycyclic aromatic hydrocarbons (PAHs) including phenanthrene, benzo(a)pyrene, and benzo(e)pyrene was studied under different estuarine conditions to elucidate the effects of dissolved organic matter (DOM), salinity, and suspended particles on PAH photodegradation in the estuarine surface water. Besides the competitive light absorption effect, DOM can accelerate the photodegradation of small PAHs such as phenanthrene by enhancing the formation of reactive intermediates and inhibit the photodegradation of large PAHs such as benzo[a]pyrene (BaP) and benzo[e]pyrene (BeP) by binding the PAH molecules. High salinity would accelerate the photodegradation of PAHs; however, the magnitude and direction of the salt effect are complicated in the presence of DOM due to the "salting-out" effect on the binding of PAHs with DOM. Suspended particulate matter in the estuary provides an alternative solid-phase photodegradation pathway for PAHs, which proceeds faster than the aqueous phase. Particulates apparently exert different effects on the photodegradation of phenanthrene (Phe) and BaP as a result of the combined effects of light absorption, particulate organic matter, PAH surface sorption, and concentration dilution in the presence of suspended particulate matter.

Spatial and temporal distribution and risk assessment of polycyclic aromatic hydrocarbons in surface seawater from the Haikou Bay, China

Spatial and temporal distributions of 14 polycyclic aromatic hydrocarbons (PAHs) were investigated in surface waters of Haikou Bay, China from October 2013 to September 2014. The total PAHs concentrations ranged from 420.2 to 2539.1 ng L(-1) with the average value of 1016.3±455.8 ng L(-1), which were predominated by low molecular weight PAHs (2- and 3-ring PAHs). Moreover, PAHs displayed spatial and temporal variations in the concentration and composition pattern. Source analysis based on isomer ratios indicated that the PAHs mostly originated from petroleum and combustion processes. An eco-toxicological risk assessment showed that the potential risk of individual PAHs had reached moderate to high levels and the total concentrations of PAHs had also reached a relatively high level compared with previous studies. This study offers important information on the pollution levels of 14 PAHs in the surface waters of Haikou Bay and recommends that prevention and control of PAHs pollution should be implemented in the region.

Occurrence and distribution of polycyclic aromatic hydrocarbons in surface water and sediments of the Danube River and its tributaries, Hungary

Polycyclic aromatic hydrocarbons (PAHs) were identified and quantified in surface water and sediments from 9 sites in the Hungarian upper section of the Danube River and its tributaries in autumn 2012. The total PAH concentrations (sum of the concentrations of 17 individual PAH compounds) in water samples ranged from 67 to 96 ng L(-1), which were predominated by two- and three-ring PAHs. The total PAH concentrations in sediments ranged from 35.2 to 288.3 ng g(-1) dw. Four-ring PAHs including fluoranthene and pyrene were the dominant species in sediment samples. The spatial distribution of PAHs in sediments was site-specific. The highest benzo[a]pyrene equivalent concentration was determined at the site located near a hazardous waste incinerator. However, the comparison of the total PAH concentrations determined with other sections of the Danube River and the environmental quality standards revealed that the PAH concentrations are relatively low in the Hungarian upper section. A selected number of concentration ratios of specific PAH compounds reflected a pattern of pyrogenic input as a major source of PAHs.