Pollutant Fluxes Research Articles

Measurements of traffic-dominated pollutant emissions in a Chinese megacity

Abstract. Direct measurements of NOx, CO and aromatic volatile organic compound (VOC) (benzene, toluene, C2-benzenes and C3-benzenes) flux were made for a central area of Beijing using the eddy-covariance technique. Measurements were made during two intensive field campaigns in central Beijing as part of the Air Pollution and Human Health (APHH) project, the first in November–December 2016 and the second during May–June 2017, to contrast wintertime and summertime emission rates. There was little difference in the magnitude of NOx flux between the two seasons (mean NOx flux was 4.41 mg m−2 h−1 in the winter compared to 3.55 mg m−2 h−1 in the summer). CO showed greater seasonal variation, with mean CO flux in the winter campaign (34.7 mg m−2 h−1) being over twice that of the summer campaign (15.2 mg m−2 h−1). Larger emissions of aromatic VOCs in summer were attributed to increased evaporation due to higher temperatures. The largest fluxes in NOx and CO generally occurred during the morning and evening rush hour periods, indicating a major traffic source with high midday emissions of CO, indicating an additional influence from cooking fuel. Measured NOx and CO fluxes were then compared to the MEIC 2013 emissions inventory, which was found to significantly overestimate emissions for this region, providing evidence that proxy-based emissions inventories have positive biases in urban centres. This first set of pollutant fluxes measured in Beijing provides an important benchmark of emissions from the city which can help to inform and evaluate current emissions inventories.

Spatiotemporal river flux and composition of nutrients affecting adjacent coastal water quality in Hainan Island, China

Human activities have changed global nutrients cycling and appreciably altered marine ecosystems in riverine-estuarine systems. This is evident by the significant shifts in the supply of nitrogen and phosphorus. However, very little is known about the concentrations and fluxes and of these nutrients and their seasonal changes in Hainan Island, China. We examined Hainan Island, which is the second largest island in China, to assess the spatiotemporal concentrations and fluxes of nutrients using seasonal data on a whole-of-system scale covering river estuaries and adjacent coastal water (2017). The annual average total dissolved nitrogen (TDN) and total dissolved phosphorus (TDP) concentrations were 77.23 ± 31.36 μmol/L and 3.25 ± 1.67 μmol/L, respectively. The annual fluxes of pollutants from the discharge of coastal rivers on Hainan Island into coastal waters were 1.8 × 104 t for TDN and 1.1 × 103 t for TDP, respectively. The month with the largest contribution to the annual pollutants load was October, which contributed 13.60% of TDN and 17.79% of TDP. In addition, the largest river fluxes were Nandu River, which contributed 7.5 × 103 t of TDN and 364 t of TDP. The annual average concentrations of pollutants in the surface coastal water were 7.60 ± 10.71 μmol/L for dissolved inorganic nitrogen (DIN) and 0.24 ± 0.31 μmol/L for dissolved inorganic phosphorus (DIP). The annual average N/P ratios in coastal rivers and seawater were 30 and 65, which were significantly higher than the Redfield ratio (N/P = 16). The DIN and DIP concentrations of most monitoring stations met the national first-class seawater standards, but the problem of nutrient pollution in some local coastal water areas was still outstanding. The coastal water quality monitoring should consider the influence of tropical storms influence on Hainan Island. The effective improvement of coastal water quality should be based on land–ocean coordination monitoring of coastal water quality and the riverine nutrient flux of Hainan Island.

A Watershed-Based Water Environment Eco-compensation Mechanism: a Case Study of Taihu Lake Basin, China

In 2008, a simple punitive eco-compensation method was implemented in the Taihu pilot region, China. However, due to the use of a flawed formula and weak compensation criterion the payments were considered unsuitable. To improve the scheme, the following issues were considered: determination of compensation criterion; compensation when water quality is acceptable; consideration of reciprocating flow; control of the errors in pollutant fluxes due to the non-synchronization of river flow and water quality data. Two alternative ways to calculate eco-compensation payments were assessed for a case study in 2013: a payment based on the “Water quality exceedance rate (WQER) method” was found to be 172 million CNY (24.9 million USD). This method avoided errors caused by the pollutant flux and considered the situations of reciprocating flow and acceptable water quality; and the “Pollutant treatment cost (PTC) method” was considered suitable for immediate implementation, although the payment was higher at 245 million CNY (35.4 million USD). The determination of compensation criterion using this method had a scientific basis, but it required perfect and reliable monitoring data. If these conditions are met, the method was considered suitable for future implementation.

Construction and Application of an Evaluation System for Soil Environmental Carrying Capacity

To understand the effect of soil environmental carrying capacity on pollutants and human activities, as well as to effectively prevent the aggravation of soil pollution and control soil environmental risks, a comprehensive indicator system for soil environmental carrying capacity is developed by analyzing the input-output flux and risk characteristics of soil pollutants. Furthermore, an evaluation method for soil environmental carrying capacity is proposed by defining safety coefficients related to evaluation indicators. Based on evaluation of soil environmental quality, the system reflects soil properties, pollution evolution trends, and risk characteristics, focusing on the soil buffering function. Further, a quantitative evaluation is carried out to assess the regional soil environmental carrying capacity of heavy metals on development land in Beijing. The results show that the soil environmental carrying capacity of Cu, Zn, Pb, and Cd in Beijing varies widely. The soil environmental carrying capacity of Cd is much lower than that of other elements. Four policy recommendations are proposed as significant for effective soil pollution prevention and control:clarifying concepts for soil environmental carrying capacity, improving the evaluation framework, constructing an information database, and implementing demonstration pilots.

THE ROLE OF NATURAL CLAYS IN THE SUSTAINABILITY OF LANDFILL LINERS

Engineered synthetic liners on their own cannot protect the environment and human health against landfill leachate pollution. Despite their initial impermeability, they are susceptible to failure during and after installation and have no attenuation properties. Conversely, natural clay liners can attenuate leachate pollutants by sorption, redox transformations, biodegradation, precipitation, and filtration, decreasing the pollutant flux. Depending on the clay, significant differences exist in their shrinkage potential, sorption capacity, erosion resistance and permeability to fluids, which affects the suitability and performance of the potential clay liner. Here, the physico-chemical, mineralogical and geotechnical characteristics of four natural clayey substrata were compared to discuss their feasibility as landfill liners. To study their chemical compatibility with leachate and rainwater, hydraulic conductivities were measured every ≈2 days spread over 7 weeks of centrifugation at 25 gravities. At field-scale, this is equivalent to every 3.4 yrs spread over 80 yrs. All the clayey substrata had favourable properties for the attenuation of leachate pollutants, although different management options should be applied for each one. London Clay (smectite-rich) is the best material based on the sorption capacity, hydraulic conductivity and low erodibility, but has the greatest susceptibility to excessive shrinkage and alterable clay minerals that partially collapse to illitic structures. Oxford Clay (illite rich) is the best material for buffering acid leachates and supporting degradation of organic compounds. The Coal Measures Clays (kaoline-rich) have the lowest sorption capacity, but also the lowest plasticity and have the most resistant clay minerals to alteration by leachate exposure.

Symbiont-bearing foraminifera as health proxy in coral reefs in the equatorial margin of Brazil.

Coral communities worldwide are progressively more stressed by anthropogenic activities that increase fluxes of sediment and other pollutants to nearshore areas. Some nearshore coral reef environments off the Equatorial margin of Brazil, including Pirangi and Maracajaú, Rio Grande do Norte (RN, Brazil), seem to be under human-induced stress. However, the horizontal extent of this stress, its effects, and assessment of the environmental response depend on the hydrodynamic conditions (circulation and deposition patterns), sedimentary facies, and the availability of biological indicators. We investigate two Brazilian live reefal corals' communities by examining seven photosymbiont-bearing species (PSB) of Foraminifera, Amphisorus hemprichii, Amphistegina gibbosa, Archaias angulatus, Borelis schlumbergeri, Heterostegina antillarum, Peneroplis carinatus, and Laevipeneroplis proteus, using numerical analysis FORAM Index (FI), grain size, and particulate organic and inorganic carbonate. Here, we show that coarse sand fraction followed by fine sand fraction and high hydrodynamics plays an important role in transportation and deposition of sediments and foraminiferal tests in the study area. According to FI results, conditions at Pirangi are not suitable for coral reef growth. Maracajaú has sites that are suitable for coral reef growth and sites where coral could not survive after a stress event. We need long-term assessments to improve our knowledge of the distribution and ecological importance of Brazilian reef-dwelling foraminifers and to extend the application of FI to monitoring management plans of the Pirangi and Maracajaú National Marine Parks by providing a first insight into the biodiversity patterns and a reliable tool of the reconstruction of paleo reef health.

Modelling the decadal dynamics of reach‐scale river channel evolution and floodplain turnover in CAESAR‐Lisflood

AbstractSedimentary deposits provide records of environmental change quantifying erosion fluxes conditioned by natural and anthropogenic disturbances. These fluxes are lagged by internal storage, particularly within floodplains, complicating reconstruction of environmental changes. The time sediment remains in storage underpins the interpretation of sedimentary records and accurate monitoring of pollutant fluxes. Turnover time is a measure of the timeframe to erode every floodplain surface. CAESAR‐Lisflood is used to simulate fluvial evolution at reach scale, providing a basis for quantifying environmental changes on the timescales of sediment storage. We evaluate the accuracy of CAESAR‐Lisflood simulations of channel changes and turnover times for alluvial floodplains using historical channel changes reconstructed for 10 reaches in northern England to quantify model accuracy in replicating mean annual erosion, deposition and channel lateral migration rates, alongside planform morphology. Here, a split‐sample testing approach is adopted, whereby five of the reaches were calibrated and the resulting parameter values were applied to the other reaches to evaluate the transferability of parameter settings. The lowest overall integrated error identified the best‐fit simulations and showed that modelled process rates were within ~25–50% of rates from historical reconstructions, generally. Calibrated parameters for some reaches are widely transferable, producing accurate geomorphic changes for some uncalibrated sites. However, large errors along some reaches indicate that reach‐specific parameterization is recommended. Turnover times are underpinned by the assumption that areas of floodplain previously unvisited by the channel are reworked. This assumption has been challenged by studies that show floodplain (re)occupation rates vary spatially. However, this limitation is less important for the short‐duration simulations presented here. The simulations reconstruct floodplain turnover times estimated by mapped rates mostly successfully, demonstrating the potential applicability of calibrated parameters over much longer timescales. Errors in the form of under‐predicted erosion rates propagated, resulting in over‐predicted turnover times by even greater magnitudes. © 2020 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.

Water quantity, quality and pollutant flux of inbound and outbound water in Zhejiang area of Taihu Basin

Water quantity, quality and pollutant flux of inbound and outbound water in Zhejiang area of Taihu Basin

Relationship between water quality in Lake Taihu and pollutant fluxes of the rivers surrounding Lake Taihu in Jiangsu Province

Relationship between water quality in Lake Taihu and pollutant fluxes of the rivers surrounding Lake Taihu in Jiangsu Province

Mapping dynamic road emissions for a megacity by using open-access traffic congestion index data

The high populations of vehicles in global megacities have raised serious mobility and sustainability challenges, such as traffic congestion, air pollution deterioration and energy consumption issues. Detailed emission inventories at the link level are a prerequisite to accurately quantifying ambient pollution concentrations and identifying hotspots of human exposure within urban areas. The increasing adoption of intelligent transportation system data in smart-city initiatives worldwide has offered unprecedented opportunities for improving transportation air quality management. Based on the open-access traffic congestion index, we construct a high-resolution emission inventory of hourly fluxes of air pollutants and carbon dioxide from on-road vehicles over the whole road network in Shenzhen, China. Fine-grained quantification of ‘excess’ emissions from rush-hour traffic is explored, finding varied emission enhancement (14.3–30.4%) for different pollutants, as well as 24.3–26.8% and 19.6–22.0% ‘excess’ consumption for gasoline and diesel, respectively, in a central business district of Shenzhen during the rush hour periods. Also, we quantified the impacts of freight activities on pollutant emissions that freight activities can largely increase the street-level emission rates of nitrogen oxides, fine particulate matter and carbon dioxide, in which heavy-duty trucks share up to 50% of the total emissions of these species. This study provides a novel approach of high-resolution traffic emission inventory construction that can be potentially utilized in many types of cities, particularly for cities suffering from data-sparse situations, and further strengthen the intelligence and accuracy of vehicle emission management.

On the Impact of Trees on Ventilation in a Real Street in Pamplona, Spain

This paper is devoted to the quantification of changes in ventilation of a real neighborhood located in Pamplona, Spain, due to the presence of street trees Pollutant dispersion in this urban zone was previously studied by means of computational fluid dynamic (CFD) simulations. In the present work, that research is extended to analyze the ventilation in the whole neighborhood and in a tree-free street. Several scenarios are investigated including new trees in the tree-free street, and different leaf area density (LAD) in the whole neighborhood. Changes between the scenarios are evaluated through changes in average concentration, wind speed, flow rates and total pollutant fluxes. Additionally, wind flow patterns and the vertical profiles of flow properties (e.g., wind velocity, turbulent kinetic energy) and concentration, horizontally-averaged over one particular street, are analyzed. The approach-flow direction is almost perpendicular to the street under study (prevailing wind direction is only deviated 4º from the perpendicular direction). For these conditions, as LAD increases, average concentration in the whole neighborhood increases due to the decrease of wind speed. On the other hand, the inclusion of trees in the street produces an increase of averaged pollutant concentration only within this street, in particular for the scenario with the highest LAD value. In fact, the new trees in the street analyzed with the highest LAD value notably change the ventilation producing an increase of total pollutant fluxes inward the street. Additionally, pollutant dispersion within the street is also influenced by the reduction of the wind velocity along the street axis and the decrease of turbulent kinetic energy within the vegetation canopy caused by the new trees. Therefore, the inclusion of new trees in a tree-free street should be done by considering ventilation changes and traffic emissions should be consequently controlled in order to keep pollutant concentration within healthy levels.

Muddying the Picture? Forecasting Particulate Sources and Dispersal Patterns in Managed Catchments

Satellite imagery and climate change projections improve our ability to map and forecast sediment sources and transport pathways at high resolution, which is vital for catchment management. Detailed assessment of temporal and spatial changes in erosion risk are key to forecasting pollutant dispersal, which affects water treatment costs and ecology. Outputs from scenario modeling of the River Derwent catchment, Yorkshire, indicate clear spatial and temporal trends in erosion risk. These trends are not picked up by using traditional methods, which rely on static land use maps. Using satellite-derived maps show that lower resolution traditional land-use maps relatively underestimate erosion risk in terms of location of source areas and seasonal variation in erosion risk. Seasonal variation in agricultural practices can be assessed by incorporating bare land variation into models, which show that erosion risk is relatively overestimated if all agricultural land is assumed to have the same character. Producing seasonal land use maps also allows the assessment of temporal variation in rainfall, which in combination with climate change projections allows for adaptable management plans. The bias in gradient in modeling, which assumes that high gradients result in greater sediment erosion risk, show that traditional models underestimate the contribution of erosion risk in lowland areas. This is compounded by the absence of artificial drainages in topographic rasters, which increases connectivity in lowland areas. By producing end member scenarios, model outputs help to inform where catchment management should be targeted, and whether seasonal interventions should be implemented. This information is vital to communicate with landowners when they implement catchment management practices, such as sediment traps and earth bunds. Adaption of erosion risk modeling practices is urgently needed in order to quantify the impact of artificial interference in which human activity disrupts ‘natural’ sediment source-to sink configurations, such as integrating new pathways and stores due to land use change and management. Furthermore, integrating higher resolution catchment modeling and improved seasonal forecasts of pollutant flux to oceans will permit more effective interventions. This paper highlights single output erosion risk maps are not effective to inform catchment management.

Network Topology and Rainfall Controls on the Variability of Combined Sewer Overflows and Loads

AbstractWater and pollutant fluxes from combined sewer overflows (CSO) have a significant impact on receiving waters. The random nature of rainfall forcing dominates the variability of sewer discharges, pollutant loads, and concentrations. An analytical model developed here shows how sewer network topology and rainfall properties variously impact the stochasticity of CSO functioning. Probability distributions of sewer discharge and concentration compare well with the results from a calibrated Storm Water Management Model in an application to a sewershed located in Dresden, Germany. The model is determined by only four parameters, three of which can be predicted a priori, two from the rainfall record and one from the network topology using geomorphological flow recession theory, while the fourth can be estimated from a short discharge time series. The sensitivity of CSO and wastewater treatment loads to network structure suggests simple topologies may be more vulnerable to poor performance. The analytical model is useful for evaluating various CSO management strategies to reduce adverse impacts on receiving waters in a probabilistic setting.

Biological Traits and the Transfer of Persistent Organic Pollutants through River Food Webs.

Freshwater organisms remain at risk from bioaccumulation and biomagnification of persistent organic pollutants (POPs), but factors affecting their transfer through food webs are poorly understood. Here, we investigate transfer pathways of polychlorinated biphenyls, polybrominated diphenyl ethers, and organochlorine through a river food web, assessing the distribution and flux between basal resources (n = 3), macroinvertebrates (n = 22), and fish (n = 1). We investigate the effects of biological traits on the observed patterns and use trait-based models to predict POP bioaccumulation. Transfer pathways differed among POPs and traits such as habitat affinity, feeding behavior, and body size explained some variation in POP burdens between organisms. Trait-based models indicated that relationships between POPs, trophic transfers, and traits were relatively well conserved across a wider array of river food webs. Although providing more consistent predictions of POP bioaccumulation than steady-state models, variability in bioaccumulation across food webs limited the accuracy of trait-model predictions. As some of the first data to illustrate how ecological processes alter the flux of pollutants through river food webs, these results reveal important links between POPs and contrasting energetic pathways. These data also show the utility of trait-based methods in the assessment of persistent contaminants, but further field validations are required.

Effects of Continuous Extreme Rainfall on Water Quality of the Dongjiang River Basin

In order to research the impact of continuous extreme rainfall on the water quality of the Dongjiang River, which is a drinking water source, the characteristics of extreme rainfall events in the basin were analyzed for last 38 years. The impacts of these events on water quality are discussed by considering both hydrological data and water quality data. Using SWAT2012 software, a high-precision basin model was established for the flux of major pollutants during extreme rainfall and water quality. The results indicate that there were 173 extreme rainfall events in the Dongjiang River basin over the past 38 years. The annual frequency of extreme rainfall events in high-flow years was higher than in other years. During the year, rainfall was mainly affected by climate, particularly from March to September (80%), with the peak rainfall usually occurring in June. Spatially, the Zengcheng-Bolo-Huizhou-Longmen area had the highest frequency of extreme events. During the study period, rainfall was significantly positively correlated with the concentrations of cyanide, Pb, Fe, Mn, TP, and with turbidity, and the correlation coefficients for the concentrations of TP and turbidity with rainfall were relatively high. Rainfall was significantly negatively correlated with pH, conductivity, the concentration of Zn, as well as some other indicators. These observations show that water quality is affected by rainfall to some extent. Turbidity, TN, ammonia nitrogen, and TP concentrations all showed increasing trends, to different degrees, during rainstorm runoff periods. Turbidity and TP concentrations showed a significant and consistent relationship with flow rate, peaking earlier than the flow rate peak (by approximately 1 d), showing a significant initial flushing effect. The pH curve showed an opposite trend to the flow rate, forming a "V" shape, which may be affected by the rainfall, soil acidity, and confluence conditions in the upstream mountains. Ammonia nitrogen was subject to initial flushing in the early stages of extreme rainfall but was diluted by the clean rainwater; initially, ammonia nitrogen showed high values that declined during the middle and late stages. The variations in pollutant loads were consistent with that of runoff flux, and the peaks in TN, ammonia nitrogen, and TP flux appeared later than the flow peak (by approximately 1 d), thus differing from the pollutant concentration peak. The pollutant load mainly showed a significant increase during storm runoff periods. The proportion of pollutant COD, ammonia nitrogen, and TP transported by 59.48% of the runoff reached 68.42%, 54.68%, and 70.20%, respectively, demonstrating the characteristics of rapid and high-impact pollutant loads. These characteristics have a great influence on the quality of Dongjiang River drinking water and it is suggested that initial rainwater treatment should be strengthened to reduce the negative impact of rainstorm runoff periods on water quality.

Quantification of eco-compensations based on a bidirectional compensation scheme in a water environment: a case study in the Jiangsu Province, China

Abstract This study delineates adjustments to the eco-compensation pilot work of the Taihu Lake Basin and the Huaihe River Basin. The number and location of original compensation sites were adjusted based on the characteristics of the river network and of the water pollution status. A bidirectional eco-compensation system based on water quality exceeding multiple was then implemented. Under this scheme, the eco-compensation payments of each city under three different compensation standards were calculated. A suitable unified short-term compensation standard for the whole province is determined among several compensation payment schemes. The results obtained after implementing the most relevant scheme reveal that (1) the bidirectional eco-compensation system is highly flexible and is viable economically, as the payment of fiscal expenditures used to pay eco-compensation is reasonable. (2) In the southern Jiangsu Province, the ratio of pollutant flux at each compensation site to the total regional flux is relatively high and may, therefore, accurately reflect the water quality condition of the main rivers flowing into the Taihu Lake. (3) The ratio of pollutant flux in the northern Jiangsu Province is low, which highlights the need for further improving the number and location of eco-compensation sites, as well as the compensation methods and standards.

Mixing layer transport flux of particulate matter in Beijing, China

Abstract. Quantifying the transport flux (TF) of atmospheric pollutants plays an important role in understanding the causes of air pollution and in making decisions regarding the prevention and control of regional air pollution. In this study, the mixing layer height (MLH) and wind profile were measured by a ceilometer and Doppler wind radar, respectively, and the characteristics of the atmospheric dilution capability were analyzed using these two datasets. The ventilation coefficient (VC) appears to be the highest in the spring (3940±2110 m2 s−1) and lower in the summer (2953±1322 m2 s−1), autumn (2580±1601 m2 s−1) and winter (2913±3323 m2 s−1). Combined with the backscatter measured by the ceilometer, vertical profiles of the PM2.5 concentration were obtained and the PM2.5 TF in the mixing layer was calculated. The TF was the highest in the spring at 4.33±0.69 mg m−1 s−1 and lower in the summer, autumn and winter, when the TF values were 2.27±0.42, 2.39±0.45 and 2.89±0.49 mg m−1 s−1, respectively. Air pollutants transport mainly occurs between 14:00 and 18:00 LT. The TF was large in the pollution transition period (spring: 5.50±4.83 mg m−1 s−1; summer: 3.94±2.36 mg m−1 s−1; autumn: 3.72±2.86 mg m−1 s−1; winter: 4.45±4.40 mg m−1 s−1) and decreased during the heavy pollution period (spring: 4.69±4.84 mg m−1 s−1; summer: 3.39±1.77 mg m−1 s−1; autumn: 3.01±2.40 mg m−1 s−1; winter: 3.25±2.77 mg m−1 s−1). Our results indicate that the influence of the air pollutants transport in the southern regions should receive more focus in the transition period of pollution, while local emissions should receive more focus in the heavy pollution period.

Performance of Composite Membrane for Palm Oil Wastewater Treatment

Polyvinylidene fluoride (PVDF) composite membranes were prepared via phase inversion method by dispersing titanium dioxide (TiO2) in the dope solution. It is aimed to study the effects of TiO2 on the membrane surface properties and thus its separation performance. The PVDF membranes modified by various TiO2 contents were characterized with respect to cross-sectional structure, average pore size, effective porosity, hydrophilicity, permeability and rejection. Maximum values of membrane hydrophilicity, membrane porosity and average pore size were achieved upon addition of 1.95% TiO2. It is found that changes in the membrane surface properties are closely corresponded with the membrane fouling. The maximum flux and rejection of organic pollutants from palm oil wastewater were recorded at 82.5 L/m2 h and 98.8 %, respectively using PVDF composite membrane incorporated with 1.95% TiO2.

Which type of pollutants need to be controlled with priority in wastewater treatment plants: Traditional or emerging pollutants?

Although wastewater treatment plants (WWTPs) can purify wastewater, they also discharge numerous contaminants into the environment through effluent discharge and sludge disposal. The occurrence, emission flux, and risk assessment of traditional pollutants (e.g., heavy metals [HMs]), and emerging pollutants (e.g., perfluoroalkyl substances [PFASs] and pharmaceutical and personal care products [PPCPs]) in WWTP emissions are of important concern. The present study analyzed 17 PFASs, 25 PPCPs, and 8 HMs in influent, effluent, and excess sludge from six WWTPs along the Yanghe River, North China. Samples were collected during four sampling campaigns from November 2016 to July 2017. The mean concentrations of PFASs and PPCPs in influent were 46.4 ng L−1 and 6.57 μg L−1, respectively; while those in effluent were 38.5 ng L−1 and 2.14 μg L−1, respectively. The highest concentrations of HMs was detected of Zn in influent (2,866 μg L−1) and effluent (3,960 μg L−1). According to the concentration composition, short-chain PFASs, fluoroquinolones (FQs), and Zn were the predominant components in both influents and effluents. The mean PFAS and PPCP concentrations in excess sludge were 5.95 ng g−1 and 3.74 μg g−1 dry weight (dw). Zn was the most abundant HMs in excess sludge with the concentration range of 156–14,271 μg g−1 dw. The compositions of PFASs, PPCPs and HMs differed between wastewater and excess sludge. The estimated emission flux of these pollutants was ordered as HMs > PPCPs > PFASs through effluent discharge and sludge disposal. Sludge disposal discharged more PPCPs and HMs into the environment than effluent discharge, which was contrary for PFASs. Relative risk of each pollutant is calculated by comparing the mean effluent concentration with the median effective concentration. Algae and fish were selected as recipient organisms to calculate the relative risk of 23 selected pollutants towards aquatic organisms. The highest-risk pollutant was Zn on both algae and fish, while perfluorobutane sulfonate (PFBS) and atenolol (ATE) posed the lowest risk. In general, HMs (regarded as traditional pollutants) presented higher risks in effluent, followed by the emerging pollutants (PPCPs and PFASs). Therefore, control of traditional pollutants should be prioritized in WWTPs in this region. This study presents an overall assessment of the current status of traditional and emerging pollutants in WWTPs and provides useful information for upgrading wastewater treatment processes.

Trace metals and persistent organic pollutants fingerprint on the particle flux in the deep subtropical NE Atlantic

Particle flux material collected in 2000 m depth in the Northeast Atlantic at 33°N and 22°W was analyzed for trace metals and persistent organic pollutants. Element enrichment factors relative to lithogenic Al were elevated indicating possible anthropogenic contributions for all trace metals except V. Polycyclic aromatic hydrocarbons, polychlorinated biphenyls and the pesticide DDT exhibited median fluxes of 10.40 μg m−2d−1,0.29 μg m−2 d−1, and 0.90 μg m−2 d−1, respectively. Flux composition reflected long range transport, with low molecular weight and low-chlorinated compounds dominating ∑15PAH and ∑23PCB. PAH isomer ratios identified fossil fuel combustion as the main ∑15PAH source. The composition of ∑4DDT suggested inputs of the fresh technical pesticide during high dust intensity periods. Pollutant fluxes showed seasonality linked to export production in the region, as well as a dependence on annual and sub-annual dust input events.