Polycyclic Aromatic Hydrocarbons (PAHs) in the intertidal sediments of Pearl River Estuary: Characterization, source diagnostics, and ecological risk assessment

Bioaugmentation strategies for polycyclic aromatic hydrocarbons-contaminated intertidal zones: Effects and microbial community succession

The intertidal zone is one of the natural systems most vulnerable to threats from polycyclic aromatic hydrocarbons (PAHs). However, the natural attenuation rate of PAHs within intertidal zones is low, posing challenges for the short-term recovery of contaminated environments. This study developed a contaminated intertidal zone simulation system and used a composite bacterial consortium containing Cellulosimicrobium sp. RS and Brucella sp. BZ for bioaugmented remediation. The degradation rate of PAHs (initial concentration: 5000 μg/kg) in the sediments reached 85.37 % after 120 days of restoration, which was significantly higher than the 29.93 % observed in the control group. High-throughput sequencing was used to analyze the structure and function of sediment microbial communities. The exogenous bacteria Cellulosimicrobium became dominant after remediation, whereas Brucella did not dominate but contributed to synergistic degradation. Network analysis and PICRUSt predictions confirmed that the microbial community evolved toward stronger PAHs degradation capabilities and degraded PAHs through ring cleavage, side-chain metabolism, and central metabolism in bioaugmented sediments. This study provides theoretical guidance and data support for bioaugmented remediation of intertidal zone pollution.

Fecundity of the snapping shrimp Alpheus estuariensis (Caridea: Alpheidae) after the oil spill in three mangroves of tropical Brazil

This study examined the impacts of oil spills since 2019 by analyzing polycyclic aromatic hydrocarbons (PAHs) in sediments and their effects on the fecundity of the shrimp Alpheus estuariensis. Samples were collected from mangroves in three Pernambuco locations: Catuama, Suape Bay, and Carneiros Beach. Ovigerous females were identified, and their eggs were counted and classified by embryonic stage. Sediment PAH levels were analyzed in freeze-dried and homogenized samples. A total of 107 females were analyzed, with varying distributions across sites. In the dry season, Carneiros showed the highest average fecundity (309 eggs), followed by Suape (238) and Catuama (154), without statistical differences. During the rainy season, Carneiros had significantly higher fecundity (605 eggs) compared to Catuama (176) and Suape (173). PAH concentrations were highest at Catuama (79 ng g-1), followed by Suape (72 ng g-1), and Carneiros (19 ng g-1). Fecundity was inversely related to PAH levels, with Carneiros showing the highest fecundity and lowest PAHs. Four years post-spill, high- molecular- weight PAHs (4-6 rings) were prevalent, posing carcinogenic and mutagenic risks. Diagnostic ratios indicated that PAHs primarily originated from pyrolytic processes, particularly combustion, highlighting biomass burning as a significant source. These findings emphasize the necessity for ongoing monitoring of impacted areas using model species to understand long-term environmental impacts on Brazil's northeastern coast.

Sources, transport and fate of polycyclic aromatic hydrocarbons (PAHs) in a typical river-estuary system in the North China: From a new perspective of PAHs loading

Sediment particles and organic carbon regulate the transport and burial of polycyclic aromatic hydrocarbons (PAHs) in the suspended particle matter (SPM) of rivers and estuarine sediments. In this study, we assessed the source, biological and health risks of the PAHs, and examined the riverine transport and burial of PAHs based on their spatial distributions and sediment surface area (SSA) in river SPM and estuarine sediments in the North China. The results showed that the river SPM was dominated by low molecular weight PAHs (LMW, 2-3 rings; 59.3 %), while the river and estuarine sediments were dominated by high molecular weight PAHs (HMW, 4-6 rings; river sediments: 70.8 % and estuarine sediments: 72.2 %) due to the degradation of LMW PAHs during transport. Quantitative estimation using principal component analysis-multiple linear regression (PCA-MLR) revealed mixed combustion of petroleum and coal to be the dominant PAH source (river samples: 67.9 % and estuary samples: 85 %). The results based on the Incremental Lifetime Cancer Risk (ILCR) model indicated that the values of dermal contact were higher than 10-6, suggesting that there were potential carcinogenic health risks. Using PAHs loading (PAHs normalized to SSA), we estimated the burial efficiency of HMW PAHs (89.1 %) to be significantly higher than that of LMW PAHs (17.8 %) in the river SPM. These findings could provide new insights into the fate of contaminants in coastal sediments, and our results provide data support and theoretical basis for the ecological and environmental protection and policy formulation for river-estuary system.

Source identification of polycyclic aromatic hydrocarbons (PAHs) in river sediments within a hilly agricultural watershed of Southwestern China: an integrated study based on Pb isotopes and PMF method

Polycyclic aromatic hydrocarbons (PAHs) in sediments represent a pervasive environmental issue that poses significant ecological risks. This study employed a combination of geographic information systems, diagnostic ratios, correlation analysis, Pb isotope ratios, and positive matrix factorization (PMF) to elucidate the potential sources of 16 priority PAHs in river sediments from a hilly agricultural watershed in Southwestern China. The results indicated that PAHs concentrations ranged from 55.9 to 6083.5 ng/g, with a mean value of 1582.1 ± 1528.9 ng/g, reflecting high levels of contamination throughout the watershed. The predominant class of PAHs identified was high molecular weight (HMW) PAHs. Diagnostic ratios and correlation analysis suggested that the presence of PHAs is likely attributed primarily to emissions from industrial dust and combustion of coal and petroleum. Furthermore, correlation analysis revealed a significant association between Pb and PAHs, indicating potential shared sources for both pollutants. Additionally, Pb isotopic analysis demonstrated that aerosols may be the primary contributor to Pb accumulation within this environment. Given the similarity in origins between Pb and PAHs, it can be inferred that PAHs predominantly originate from aerosols associated with coal combustion, industrial dust emissions, and vehicle exhaust. This inference is further supported by PMF results which yielded consistent findings with those derived from Pb isotopes analysis. Moreover, PMF estimated three major sources contributing 57.63%, 23.57%, and 18.80%, respectively. These findings provide novel insights into identifying the sources of PAHs in river sediments within hilly agricultural watersheds in Southwest China, thereby establishing a scientific foundation for enhancing environmental quality in agricultural regions.

Polycyclic aromatic hydrocarbons in surface sediments of the western Bay of Bengal: Distribution, sources, and ecological risk assessment

This study investigated the distribution, sources, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of the Western Bay of Bengal (WBoB). Coastal, shelf and slope sediments from the WBoB, collected from different research cruises, were analysed for 16 priority PAH pollutants. Total PAHs (TPAHs) were in the range of 1.87-918.79 ng/g and exhibited a significant association with organic matter and silt content with a predominance of high molecular weight (HMW) PAHs congeners. The preferential degradation of the labile low-molecular-weight (LMW) PAHs resulted in the sedimentary accumulation of HMW congeners. A comparison with reported values from other oceanic areas revealed a relatively low concentration of PAHs in WBoB. The isomeric ratios of PAHs could suggest a pyrogenic or petrogenic (crude oil) origin of PAHs. Principal component analysis indicated the dominance of HMW PAHs (petrogenic or combustion) over the LMW fraction. Based on sediment quality guidelines, four congeners [Pyrene (Py), Benzo[a]anthracene (BaA), Chrysene (Ch), and Dibenzo[a,h]anthracene (DbA)] exceeded the threshold effect levels, indicating an adverse impact of these PAHs on the benthic fauna occasionally. The corresponding risk quotients further indicated a moderate risk caused by Py, BaA, and Benzo[b]fluoranthene (BbF) to the biota. This study underscores the importance of proactive management and mitigation strategies to safeguard these vital oceanic ecosystems from the adverse effects of PAHs and other hazardous materials.

Distribution and sources of polycyclic aromatic hydrocarbons in cascade reservoir sediments: influence of anthropogenic activities and reservoir hydrology

The construction of dams has caused disruptions to river connectivity, leading to alterations in the deposition of hydrophobic organic contaminants in reservoir sediments. Further investigation is warranted to explore the impact of cascade reservoirs with differing hydrological characteristics on polycyclic aromatic hydrocarbons (PAHs) distribution in sediment. This study examines the presence of 30 PAHs in the sediments collected from six cascade reservoirs situated in the Wujiang River basin during January and July 2017. The results showed that Σ30 PAHs ranged from 455-3000 ng/g dw (mean 1030 ng/g dw). Anthropogenic activities and reservoir hydrology determined the distribution trend of PAHs in sediments, with an overall increase from upstream to midstream and then a decrease downstream. The PAH levels were highly linked to the secondary industry (P < 0.05). This was further supported by the relationship between the PAH emissions from coal combustion and traffic sources analyzed by the positive matrix factorization model and economic parameters in the wet season (P < 0.01). At the same time, reservoir age (RA) showed a positive correlation with PAH concentrations (P < 0.05), while hydraulic retention time (HRT) exhibited a negative correlation with PAH levels (P = 0.03). The relationship between total organic carbon (TOC) and PAHs in stream sediments worldwide was nonlinear (P < 0.01), with PAH concentrations initially rising and then falling as TOC levels increased. Concerns regarding carcinogenic risk were raised due to contributions from coal and vehicular sources, with the risk increasing with RA.

Spatial distribution of PAHs and microbial communities in intertidal sediments of the Pearl River Estuary, South China

The exploration of sediment pollution caused by PAHs and its impact on microbial communities can provide valuable insights for the remediation of sediments. The spatial distribution of PAHs and their impact on the microbial community within the Pearl River Estuary were investigated in this study. The findings revealed that the total concentration ranges of 16 PAHs were between 24.26 and 3075.93 ng/g, with naphthalene, fluorene, and phenanthrene potentially exerting adverse biological effects. More PAHs were found to accumulate in subsurface sediments, and their average accumulation rates gradually decreased as the number of rings in PAHs increased, ranging from 180 % for 2-ring to 36 % for 6-ring. The phyla Proteobacteria, Bacteroidetes, Actinobacteria, and Chloroflexi were found to dominate both surface and subsurface sediments The correlation between microbial genera and PAHs contents was weak in sediments with low levels of PAHs contamination, while a more significant positive relationship was observed in sediments with high levels of PAHs contamination. The physicochemical properties of sediments, such as pH, soil structure and Cu significantly influence bacterial community composition in highly contaminated sediments. Additionally, the network analysis revealed that certain bacterial genera, including Novosphingobium, Robiginitalea and Synechococcus_CC9902, played a pivotal role in the degradation of PAHs. These findings are significant in comprehending the correlation between bacterial communities and environmental factors in intertidal ecosystems, and establish a scientific foundation for bioremediation of intertidal zones.

Characteristics, sources analysis, and risk assessment of polycyclic aromatic hydrocarbon contamination in surface sediments surrounding tourist island

Surface sediment samples were collected from the surrounding sea areas of the two largest tourist islands in Sanya City, China, to compare and assess the sources, distribution, and ecological risks of 16 polycyclic aromatic hydrocarbons (PAHs). The total PAHs concentrations ranged from 31.16 to 163.3 ng/g, with an average concentration of 102.46 ng/g, which is still lower than the levels detected in most other sediment studies worldwide. PAHs from coal combustion (Flu, Pyr, Fl, Phe) showed positive correlations with TOC, Silt, and Clay, indicating that these PAHs are easily adsorbed in muddy and silty sediments. Sanya Bay is primarily composed of mud and silt, whereas Haitang Bay is mainly sandy. This corresponds to the significantly higher concentrations of Fl, Phe, and Pyr in Sanya Bay compared to Haitang Bay. The main industrial activities in the study area are related to power and heat production and supply. The results indicate that the primary sources of sediment PAHs are high-temperature combustion during heavy industrial production, followed by maritime transportation and petroleum sources. Overall, the PAHs pollution levels in the study area range from slight to moderate. Sediment quality assessments show that only Ace and Phe have higher individual risk values. Six stations in Sanya Bay have higher adverse impact risks, while in Haitang Bay, only HT07 poses a high risk to biological impact. These two areas require enhanced monitoring and pollution source control.

Polycyclic aromatic hydrocarbons and their halogenated derivatives in soil from Yellow River Delta: Distribution, source apportionment, and risk assessment

The distribution of polycyclic aromatic hydrocarbons (PAHs) and halogenated PAHs (HPAHs) in surface soils from the petroleum industrial area of the Yellow River Delta (YRD) in China were investigated. The total concentrations of 16 PAHs ranged from 19.6 to 1560 ng/g, while 22 HPAHs ranged from 2.44 to 14.9 ng/g. Moreover, a high degree of spatial distribution heterogeneity was observed for both PAHs and HPAHs, which is likely attributed to the distinct industrial activities in studied area. The combustion of biomass and petroleum were identified as primary sources of soil PAHs and HPAHs in the YRD. Furthermore, benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[g,h,i]perylene exhibited high ecological risks (with risk quotients of 1.47, 1.44, and 1.02, respectively) in specific sites within the YRD. Considering the high toxicity of HPAHs and their potential joint environmental effects with PAHs, continuous attention should be directed towards the environmental risks associated with both PAHs and HPAHs.

Distribution, sources, and eco-risk of Current-Use Pesticides (CUPs) in the coastal waters of the northern Shandong Peninsula, China

This study investigated the spatial distributions and seasonal variations of 19 CUPs in the coastal areas of the Shandong Peninsula and its surrounding rivers and assessed their ecological risk. In freshwater and seawater, insecticides (chlorpyrifos, methoxychlor, and pyridaben), as well as fungicides (fenarimol) and herbicides (dichlobenil) were the main pollutants (Detection Frequency: 100 %). Spatially, during winter, the regional pollution levels of Σ19CUPs in seawater showed a trend of Laizhou Bay (LZB, mean:4.13 ng L-1) > Yellow River Estuary (YRE, mean:2.57 ngL-1) > Bohai Bay (BHB, mean:2.21 ng L-1) > Yanwei Area (YWA, mean:1.94 ng L-1). The similarities of major substances between rivers and the marine environment suggest that river discharge is the main source of CUPs pollution in coastal areas. In summer, CUPs in rivers posed a high risk. In winter, the risk significantly decreased, indicating a moderate overall risk. Seawater exhibited a low risk in winter.

Risk assessment of trace metals and polycyclic aromatic hydrocarbons in seawater of typical bays in the Bohai Sea

The ecological risks of trace metals (Cu, Zn, As, Cd, Pb, and Hg) and PAHs in seawater from three typical bays of the Bohai Sea (the Liaodong Bay, Bohai Bay, and Laizhou Bay) were comprehensively assessed by recompiling 637 sites. Results highlighted that scrutiny should be given to the ecological risks of Cu (3.80 μg/L) in the Bohai Bay and Hg (0.23 μg/L) in the Laizhou Bay. Conversely, the Liaodong Bay exhibited negligible ecological risks related to trace metals. The risks of ΣPAHs in the Liaodong Bay, Bohai Bay, and Laizhou Bay were moderate, with mean concentrations of 368.16 ng/L, 731.93 ng/L, and 187.58 ng/L, respectively. The source allocation of trace metals and PAHs required consideration of spatial variability and anthropogenic factors, which greatly affected the distribution and composition of these pollutants. The combined ecological risks in the Bohai Bay (6.80 %) and Laizhou Bay (5.43 %) deserved more attention.

A century-long record of polycyclic aromatic hydrocarbon deposition in the Old Yellow River Estuary, China

Polycyclic aromatic hydrocarbons (PAHs) are potential geochemical indicators for assessing the impact of human activities and can be used to reconstruct historical human activities. This study collected a 108 cm sediment core from the 5th lobe of the Yellow River Delta for the first time and analyzed the historical distribution characteristics of PAHs in this area. The results showed that the sedimentation history of the core was from 1908 to 2014. The average value of PAHs was 28.93 ng/g. Biomass and coal combustion sources were the main sources of PAHs in the low-value areas, while oil spill sources were the main sources in the significantly higher PAHs areas in the 1960s, mid-1980s, late 1990s, and late 2010s, which was consistent with the development history of Shengli Oilfield. Compared with global estuaries, the historical industrial activity intensity in this area was weaker.

Occurrence, spatiotemporal distribution patterns,partitioning and risk assessments of multiple pesticide residues in typical estuarine water environments in eastern China

The low terrain and the prosperous agriculture in the east of China, have caused the accumulation of pesticide residues in the estuaries. Therefore, this study analyzed the spatiotemporal distribution and partition tendency of 106 pesticides based on their abundance, frequencies, and concentrations in the aquatic environment of 16 river estuaries in 7 major basins in the eastern China by using solid-phase extraction (SPE) with high-performance liquid chromatography tandem mass spectrometry (HPLC‒MS/MS) and gas chromatography tandem mass spectrometry (GC‒MS/MS). In addition, potential risk of multiple pesticides was also evaluated. The results showed that herbicides were the dominant pesticide type, while triazines were the predominate substance group of pesticide. In addition, triadimenol, vinclozolin, diethylatrazine, prometryn, thiamethoxam, atrazine, and metalachlor were the major pesticides in the water, while prometryn, metalachlor, and atrazine were the main pesticides in the sediment. The average total concentration of pesticide was 751.15 ng/L in the dry season, 651.17 ng/L in the wet season, and 617.37 ng/L in the normal season, respectively. The estuaries of the Huai River Basin, the Yangtze River Basin, the Hai River Basin, and the Yellow River Basin have been affected by the low pollution treatment efficiency, weak infrastructure, and agricultural/non-agricultural activities in eastern China, resulting in relatively serious pesticide pollution. The estuaries of Huaihe River, Yangtze River, Xiaoqing River, and Luanhe River had large pesticide abundance and comparatively severe pesticide pollution, while the estuaries of Tuhai River and Haihe River had heavy pesticide contamination in the sediment, which might be induced by historical sedimentary factors. The log KOC values showed that except for thioketone, other pesticides were relatively stable due to the adsorption by sediment. The ecological risk assessment results indicated that insecticides had a high risk. Teenagers were the most severely affected by the noncarcinogenic risk of pesticides, while adults were mostly affected by the carcinogenic risk of pesticides. Therefore, pesticide hazards in the water environment of estuaries in eastern China needs to be further close supervision.

Environmental assessment of oyster beds in the northern Arabian Gulf Coast of the United Arab Emirates

The United Arab of Emirates (UAE) hosts valuable coastal and marine biodiversity, and oysters are one of the habitants of its marine ecosystem. Oysters play an essential role in the nearshore coasts where they work as an active filter. They filter nutrients, phytoplankton, sediments, heavy metals, and toxins out of the water, which improves the water quality. This is the first study that characterizes oyster bed habitats in the UAE by analyzing water quality parameters, polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs)and heavy metals in water, sediments and oyster samples collected from five locations along the coasts of Sharjah, Ajman, and Umm al Quwain. Oyster bed areas supported a diverse assemblage of benthic life including oysters, scallops, pen shells, hard corals, and macroalgae. Mobile species in these habitats included groupers, emperors, snappers, sea snakes, among others. The phytoplankton assemblages were dominated by diatoms, dinoflagellates, and small cryptophytes. Harmful diatom Pseudonitzschia was found in all locations. No detectable concentrations of PAHs and OCPs were reported in this study, and water quality parameters were within the acceptable levels for the region. On the other hand, water quality index was reported marginal, mostly due to the presence of higher than acceptable concentrations of chromium and mercury in all sites studied. Bioconcentration factors concluded that oysters were able to bioconcentrate metals such as arsenic, cadmium, chromium, and zinc, when compared to water. No detectable concentrations of lead and mercury were reported in oysters, suggesting higher depuration rates for those metals.

Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in sediments from Baiyang Lake, China

The issue of polycyclic aromatic hydrocarbons (PAHs) has been an environmental focus worldwide. In this study, the contents, sources, and ecological risks of sixteen PAHs in the sediment of Baiyang Lake were estimated, and a list of priority pollutants was established. The total PAH contents ranged from 114 to 1010 ng·g-1. The composition of PAHs indicated that 4- to 6-ring PAHs predominated in the sediment samples. The diagnostic ratio analysis showed that combustion sources were predominant for PAHs in Baiyang Lake. Specifically, the positive matrix factorization model indicated that diesel engine emissions, gasoline engine emissions, wood combustion sources, and coal combustion sources contributed 22, 32, 24, and 22% of ∑PAHs, respectively. Based on the sediment quality guidelines, mean effects range median quotient, ecological risk quotient, and toxicity equivalent quotient methods, the comprehensive assessment results of PAHs in Baiyang Lake sediments indicated that the ecological risks were at medium and low levels. The priority pollutant list showed that benzo[b]fluoranthene and benzo[a]pyrene were the highest-priority pollutants and thus should be given more attention.

Dissemination and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in water and sediment of Buriganga and Dhaleswari rivers of Dhaka, Bangladesh

Concentration, source, ecological and health risks of sixteen polycyclic aromatic hydrocarbons (PAHs) were estimated for water and sediment samples of two urban rivers namely Buriganga River (BR) and Dhaleswari River (DR). The mean concentration of ∑PAHs in BR water and sediment were 9619.2 ngL-1 and 351.6 ngg-1, respectively. Furthermore, the average PAH concentrations detected in DR water and sediment were 1979.1 ngL-1 and 792.9 ngg-1, respectively. The composition profile showed that 3-ring PAHs were dominant in the water matrix; however, 5-ring PAHs were prevalent in the sediment samples of both rivers. Sources apportion study of PAHs indicated that mixed combustion and petroleum sources are responsible for PAHs contamination in the rivers. Ecological risk study of water suggested that the aquatic lives of both rivers are threatened by Fla, BbF, BkF, DahA, and IcdP, as presented above the threshold level. Comparison with sediment quality guidelines (SQGs) indicated that adverse effects might cause occasionally in the sediment ecosystem in DR at certain sampling sites for Nap, Acy, Fl, Phe, Ant, Pyr, Chr, BaP, and DahA. On the other hand, the presence of Nap, Acy and DahA might occasionally cause adverse biological effects in the BR sediment ecosystem. Estimated hazard quotient (HI > 1) and carcinogenic risk (CRtotal > 10-4) values indicated that local inhabitants living in the vicinity of the rivers are prone to high health risks.

Spatial assessment of triazole organic compounds in surface water from the coastal estuaries to the East China sea

Triazole is widely used in the synthesis of pharmaceuticals, pesticides, and fungicides. However, triazole organic compounds are often a source of toxicity in the water environment due to the presence of chlorobenzene. This study reported on the occurrence and distribution of 15 TrOCs in the surface waters of estuaries and the East China sea, and identified the influences of TrOCs originating from the estuarine environment on the ocean. The results showed that the total concentrations of ∑TrOCs in the surface water of estuaries along the coasts of Jiangsu (JS), Zhejiang (ZJ), and Shanghai (SH), China ranged from 0.020 to 104 ng L^-1 (7.49 ± 18.2 ng L^-1), whereas they ranged from 0.235 to 1.25 ng L^-1 (mean 0.711 ± 0.235 ng L^-1) in the East China sea. Difenoconazole and tebuconazole were the dominant TrOCs in the estuaries, whereas fenbuconazole and hexaconazole dominated in the ocean. TrOCs in surface water of estuaries showed a continuous spatial distribution and presented regional characteristics mainly related to agricultural activities. In contrast, TrOCs in the East China Sea showed a low spatial variation and dispersion, which may be related to complex disturbance by currents and dilution. The low levels of estuarine TrOCs measured in SH estuaries (<0.5 ng L^-1) indicates that the Yangtze River may only pose a low-level TrOC contamination risk to the East China Sea. Moreover, estuary transport in the estuaries of ZJ may have influenced the occurrence of TrOCs in the offshore East China Sea area, although they may have also undergone a filter process in the estuary turbid zone; whereas it had little influence on the open sea. This study can act as a critical reference for the presence of TrOCs in surface water both estuaries and the ocean.

Characteristics and source analysis of polycyclic aromatic hydrocarbons in organisms and manure near Ardley Island, Antarctica

In order to better understand the migration and accumulation behavior of polycyclic aromatic hydrocarbons (PAHs) in biological chains in the cold environment around the Ardley Island, a variety of biological and penguin manure samples during China's 36th Antarctic Scientific expedition have been collected and studied. A certain difference in PAHs concentration was observed in the environmental samples, and the order of size was as follows: fish > limpets > krill > manure > brown alga > mosses. The percentage of PAHs with different ring numbers in brown alga, moss, and krill was in the following order: three rings > two rings > four rings > five rings > six rings. The proportion of HMW-PAHs in limpets and fish samples was higher than that in brown alga, moss, manure, and krill samples. The main source of PAHs in environmental samples near Ardley Island is oil, which may be due to the development of tourism in Antarctica, the number of ships and human activities around the region. Therefore, it is imperative to strengthen the protection of the ecological environment in the area around Ardley Island.

The distribution, sources and health risk of polycyclic aromatic hydrocarbons (PAHs) in sediments of Liujiang River Basin: A field study in typical karstic river

The accumulation of PAHs in sediments of Liujiang River Basin were investigated to disclose the sources, input processes and toxicity risk of PAHs in a typical karstic river. The results revealed the concentrations of ∑₁₅PAHs are ranging from 111.97 to 593.39 ng/g, most of which are centralized in upstream and midstream of Liujiang River. Positive Matrix Factorization identified PAHs are mainly from the mixed combustion of oil and coal, biomass combustion and oil products leaking. Redundancy analysis manifested mixed accumulation should be the main approach of PAHs that inputting sediment. The values of RQ_NCs and RQ_MPCs suggested the moderate contamination of PAHs. The higher HQ and ILCR indicated the ingestion of PAHs are the main way to impact public health, while children should be more susceptible to PAHs. The values of HQ and ILCR indicated the overall low non-carcinogenic risk of PAHs, but relatively high carcinogenic risk of PAHs.

Accumulation of heavy metal(loid)s and polycyclic aromatic hydrocarbons in the sediment of the Prahovo Port (Danube) and associated risks

The current study investigated the concentrations, possible sources, toxicity, and ecological risk of eight heavy metal(loid)s (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) and sixteen priority polycyclic aromatic hydrocarbons (PAHs) in surface sediments in the port of Prahovo (Danube, Serbia). Among the examined HMs, the most abundant was Cu (38.3 mg/kg), followed by Zn. The Σ16PAHs concentrations ranged from 25 to 112.5 µg/kg, with 4-ring PAHs (17.3 µg/kg) being the most dominant in the study area. The mean and maximum values of HMs and PAHs obtained in this study were below the national regulatory limits and within environmental criteria. Particularly significant correlations between As, Cd, Cr, Ni, Pb, Zn, 5-, 6-ring PAHs, as well as between Pb and Hg, indicated their similar anthropogenic sources, pathways, and adsorption mechanisms. These findings were confirmed by cluster analysis and principal component analysis. Diagnostic ratios demonstrated that contamination in inner port stations was characterized by pyrogenic sources, while PAHs of petrogenic origin prevailed in samples near the port entrance. The mean ERM quotient (mERMq), toxic risk index (TRI), and toxic equivalent quotient (TEQ) were also calculated to assess the toxicity of the investigated HMs and PAHs in sediments. Positive matrix factorization suggested four potential sources as the main components of sediment contamination, whereas the risk assessment indicated a low or relatively insignificant risk of adverse biological effects from the combined toxicity of HMs and PAHs for the entire study area.

Multi-index assessment of heavy metal contamination in surface sediments of the Pearl River estuary intertidal zone

Surface sediments from 21 stations within the Pearl River estuary (PRE) intertidal zone were sampled for heavy metal contamination analysis. Average heavy metal concentrations (mg/kg) in the PRE intertidal zone were 118.5 (Cr), 860.4 (Mn), 19.5 (Co), 72.5 (Ni), 128.1 (Cu), 198.5 (Zn), and 73.0 (Pb), with the concentrations of Mn, Co, Ni, Cu, and Zn being significantly higher than their corresponding background values. The enrichment factor (EF) and geo-accumulation index (I_geo) reveal the same contamination status, with Pb, Ni, Co, Mn, and Cu showing slight to moderate contamination. Overall, the combined heavy metal concentration in the PRE intertidal surface sediments had a 24.7 % probability of toxic effects on aquatic biota based on the joint probabilistic risk (JPR) approach. Principal component analysis (PCA) coupled with the correlation analysis (CA) revealed that the heavy metal contamination in the PRE intertidal zone might originate from natural and anthropogenic sources.

Effects of PAHs on meiofauna from three estuaries with different levels of urbanization in the South Atlantic

Estuarine environments are suggested to be the final receivers of human pollution and are impacted by surrounding urbanization and compounds carried by the river waters that flow from the continent. Polycyclic aromatic hydrocarbons (PAHs) are among the contaminants that can reach estuaries and can directly affect marine conservation, being considered highly deleterious to organisms living in these environments. This research investigated the meiofauna of three estuaries exposed to different levels of urbanization and consequently different levels of PAH concentrations, in order to assess how these compounds and environmental factors affect the distribution, structure and diversity of these interstitial invertebrates. A total of 15 major meiofauna groups were identified, with Nematoda being the dominant taxon (74.64%), followed by Copepoda (9.55%) and Polychaeta (8.56%). It was possible to observe significant differences in all diversity indices studied in the estuaries. With the exception of average density, the diversity indices (richness, Shannon index and evenness) were higher in the reference estuary, Goiana estuarine system (GES). On the other hand, the Timbó estuarine system (TES) had the lowest Shannon index value and richness, while the Capibaribe estuarine system (CES) had the lowest evenness value. The latter two estuaries (TES and CES) presented intermediate and high levels of urbanization, respectively. The ecological quality assessment (EcoQ) in the studied estuaries was classified from Poor to Moderate and the estuary with the lowest demographic density in its surroundings, GES, showed a better ecological quality (Moderate EcoQ). A significant distance-based multivariate linear modelling regression (DistLM) was observed between the environmental variables and the density of the meiobenthic community, where PAHs and pH were the main contributors to organism variation. The sediments were characterized by predominance of very fine sand and silt-clay in the most polluted environments, while the control site environment (GES) was dominated by medium grains. The highest concentrations of PAHs were found in the most urbanized estuaries, and directly affected the structure of the interstitial benthic community. The metrics used in the present study proved to be adequate for assessing the environmental quality of the investigated estuaries.

Polycyclic aromatic hydrocarbon sequestration by intertidal phototrophic biofilms cultivated in hydrophobic and hydrophilic biofilm-promoting culture vessels

Phototrophic biofilms collected from intertidal sediments of the world's largest tidal mangrove forest were cultured in two sets of a biofilm-promoting culture vessel having hydrophilic glass surface and hydrophobic polymethyl methacrylate surface wherein 16 priority polycyclic aromatic hydrocarbons (PAHs) were spiked. Biofilms from three locations of the forest were most active in sequestering 98-100% of the spiked pollutants. PAH challenge did not alter the biofilm phototrophic community composition; rather biofilm biomass production and synthesis of photosynthetic pigments and extracellular polymeric substances (EPS) were enhanced. Photosynthetic pigment and EPS synthesis were sensitive to vessel-surface property. The lowest mean residual amounts of PAHs in the liquid medium as well as inside the biofilm were recorded in the very biofilm cultivated in the hydrophobic flask where highest values of biofilm biomass, total chlorophyll, released polysaccharidic (RPS) carbohydrates, RPS uronic acids, capsular polysaccharidic (CPS) carbohydrates, CPS proteins, CPS uronic acids and EPS hydrophobicity were obtained. Ratios of released RPS proteins: polysaccharides increased during PAH sequestration whereas the ratios of CPS proteins: polysaccharides remained constant. Efficacious PAH removal by the overlying phototrophic biofilm will reduce the entry of these contaminants in the sediments underneath and this strategy could be a model for "monitored natural recovery".

Spatiotemporal PAH levels in the coastal sediment of Samsun, a Metropolis between Turkey's two largest deltas

Surface sediments were sampled seasonally along the Samsun coastline to assess the source, distribution, and ecological risk of 16 polycyclic aromatic hydrocarbons (PAHs). The total PAHs levels, varied between 71.64 and 1186.87 ng g^-1 with the mean of 295.79 ng g^-1, were consistent with sediment studies worldwide. Diagnosis rates revealed that PAHs in sediments along the Samsun coastline are primarily sourced from biomass, coal and petroleum combustion and petroleum at lesser extent. The three-ring PAHs (34.9 %) were proportionally high, followed by 4-ring PAHs (25 %). Sediment quality guidelines (SQGs), administered to evaluate biological effects of individual PAH, indicated adverse biological effects (≥TEL and < PEL) seasonally in some stations. With respect to the risk quotient, the risk arisen by PAHs in the coastal sediments of Samsun found to be moderate to high ecological risk.

Combining sequential extraction and 3D fluorescence to investigate the behavior of antibiotic and polycyclic aromatic hydrocarbons during solar drying of sewage sludge

Solar drying and liming are commonly used for sludge treatment, but little is known about their efficiency on antibiotics and Polycyclic Aromatic Hydrocarbons (PAHs) removal. This study aimed to investigate the removal of antibiotics and PAHs during solar drying of Limed Sludge (LS) and Non-Limed Sludge (NLS). Thus, organic matter fractionation and 3D fluorescence were used to assess the accessibility and the complexity of organic matter. 2 experiments have been conducted using LS and NLS for 45 days of drying in a pilot scale tunnel. Physicochemical results indicated significant decrease of water content (90%) for both sludge samples within 15 days of drying. For both treatments, the removal of total organic carbon and total nitrogen was low and similar for both treatments. Through this study, it has been confirmed that liming and drying contributed to a strong modification of the organic matter quality with an increase of its accessibility. On the other hand, drying alone increased the less accessible compartments, while the presence of lime affected the interconnexion between the organic matter pools. 3D fluorescence confirmed the obtained results and indicated that LS leads to obtaining more simple molecules in the most accessible compartments, while NLS leads to obtaining more complex molecules in the less accessible compartments. In addition, solar radiations and leaching may contribute to the significant removal (p < 0.01) of roxithromycin, benzo(a)anthracene, chrysene, benzo[k]fluoranthene, benzo[a]pyrene, and benzo(g, h, i) perylene in the presence of lime. Furthermore, the evolution of organic matter pools in terms of accessibility and complexity may drive the bioavailability of these pollutants, leading to their significant removal.

An Advanced PMF Model Based on Degradation Process for Pollutant Apportionment in Coastal Areas

With increasing stress posed to the marine ecosystem and coastal communities, prevention and control of coastal pollution becomes urgent and important, in which the identification of pollution sources is essential. Currently, the pollutant source apportionment in coastal areas is mainly based on receptor models, such as the positive matrix factorization (PMF) model. Nevertheless, these models still lack consideration of the changes of pollutant behaviors (e.g., the degradation of pollutants) which cause the differences in pollutant compositions. Subsequently, the source apportionment via receptor models only based on the monitoring data may not be consistent with the one in pollution sources. To fill this gap, a pollutant degradation model was firstly developed in this study. Accordingly, the degradation model was inversed to estimate the pollutant concentrations at their emitting sources, based on the monitoring concentration in the coastal area. Finally, the estimated concentrations were fed to the PMF model for pollutant source apportionment, advancing the PMF model with degradation process. To demonstrate the feasibility and accuracy of the developed model, a case study of source appointment was carried out based on the polycyclic aromatic hydrocarbons (PAHs) in the sediments of the Pearl River Estuary. The results indicated the same types of emission source identified by the original and advanced PMF models, which were oil spill, biomass and coal combustion, and traffic emission. Nevertheless, the contributions of sources were significantly varied between the two models. According to the analyses based on emission inventory, the offsets of the results from the original PMF model were −55.4%, 22.7%, and 42.2% for the emission sources of oil spill, biomass and coal combustion, and traffic emission, respectively. Comparatively, the offsets for the advanced PMF model narrowed down to −27.5%, 18.4%, and −4.4%. Therefore, the advanced PMF model is able to provide satisfactory source apportionment for organic pollutants in coastal areas, and thus further provide a scientific basis for marine pollution prevention and control.

Pollution Assessment and Source Apportionment of Soil Heavy Metals in a Coastal Industrial City, Zhejiang, Southeastern China

In this research, Ningbo City, a typical industrial city in southeastern China, was selected as the study area, and the concentrations of 12 heavy metals (Cd, Cr, Ni, Pb, Zn, Cu, Hg, As, Co, V, Se, and Mn) were measured at 248 sampling points. Pollution index methods were used to assess the status of soil heavy metal contamination, and the Positive Matrix Factorization (PMF) model and Unmix model were integrated to identify and apportion the sources of heavy metal contamination. The results indicated that nearly 70% of the study area was polluted by heavy metals, and that Ni, Cr, and Zn were the main enriched heavy metals. The five sources identified using the PMF model were a geological source, an atmospheric deposition source, a transportation emissions source, a mixed source of agriculture and industry, and a mixed source of geology and industry. The four sources identified using the Unmix model were a mixed source of geology, agriculture, and industry (14.27%); a transportation emissions source (4.76%); a geological source (14.7%); and a mixed source of geology and industry (66.28%). These results have practical significance, as they can help to carry out pollution source risk assessment and give priority to the management of pollution source control.