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Polycyclic aromatic hydrocarbons (PAHs) and the nitrogen heterocyclic analogues (N-PAHs) are known to co-exist in environmental samples. Despite the known toxicity in polluted soils, their distribution remains to be elucidated in specific regions. This study investigated the occurrence and distribution PAHs and N-PAHs in soils from the Niger Delta. Physico-chemical analysis shows that Niger Delta soils are calcic, low in cation-exchange capacity (CEC); with ƩPAHs and ƩN-PAHs ranges of 663.9–1,618,821.2 µg/kg and 488.2–3,510.3 µg/kg, respectively. The most abundant PAHs were 2,6-dimethyl-naphthalene and 4,7-phenanthroline. Petrogenic-PAHs dominated the crude oil spill sites; while, pyrogenic-PAHs were abundant in drilling and gas flaring sites. Oil spill sites recorded elevated levels of N-PAHs, with 3-rings and carcinogenic-N-PAHs showing dominance. Furthermore, ƩPAHs and ƩN-PAHs in the oil rich region exceeded the Alberta and Canadian soil quality guidelines and, are also higher than PAHs/N-PAHs studies in literature. Risk assessment based on Benzo[a]pyrene toxic equivalency (TEQ-B[a]Peq) suggests high ecological risks. This is the first study on the occurrence and distribution of PAHs/N-PAHs in the area, and the data could serve a baseline purpose for risk assessment and remediation of contaminated sites.

In this study, the biodegradation of phenanthrene was investigated in newly isolated endophytic fungal strains, Fusarium sp. (KTS01), Trichoderma harzianum (LAN03), Fusarium oxysporum (KTS02), Fusarium oxysporum (LAN04), and Clonostachys rosea (KTS05). This was performed under different carbon:nitrogen ratios (10:1, 20:1, and 30:1) using different nitrogen sources (urea and malt extract and ammonium nitrate) over a 30 d incubation period in both static and agitated liquid media. The kinetics of polycyclic aromatic hydrocarbons (PAH) mineralisation to CO

Numerous harmful chemicals are introduced every year in the environment through anthropogenic and geological activities raising global concerns of their ecotoxicological effects and decontamination strategies. Biochar technology has been recognized as an important pillar for recycling of biomass, contributing to the carbon capture and bioenergy industries, and remediation of contaminated soil, sediments and water. This paper aims to critically review the application potential of biochar with a special focus on the synergistic and antagonistic effects on contaminant-degrading microorganisms in single and mixed-contaminated systems. Owing to the high specific surface area, porous structure, and compatible surface chemistry, biochar can support the proliferation and activity of contaminant-degrading microorganisms. A combination of biochar and microorganisms to remove a variety of contaminants has gained popularity in recent years alongside traditional chemical and physical remediation technologies. The microbial compatibility of biochar can be improved by optimizing the surface parameters so that toxic pollutant release is minimized, biofilm formation is encouraged, and microbial populations are enhanced. Biocompatible biochar thus shows potential in the bioremediation of organic contaminants by harboring microbial populations, releasing contaminant-degrading enzymes, and protecting beneficial microorganisms from immediate toxicity of surrounding contaminants. This review recommends that biochar-microorganism co-deployment holds a great potential for the removal of contaminants thereby reducing the risk of organic contaminants to human and environmental health Refereed/Peer-reviewed

Applying digestate, the residue from anaerobic digestion, to soil as a replacement for inorganic fertiliser is of growing interest in agriculture. However, the impacts of different fractions of digestate on the soil carbon (C) cycle remain unclear and provide the focus for the research reported here. We examined the effects of applying whole digestate (WD) and solid digestate (SD) on carbon dioxide (CO2C) efflux, the concentrations of dissolved organic carbon (DOC), microbial biomass C (Cmicro) and phospholipid fatty acids, alongside carbon use efficiency (CUE). A 21‐day laboratory microcosm incubation was used to investigate the impacts of digestate when applied to two grassland soils of high versus low initial nutrient content. Application rates for SD and WD were based on recommended nitrogen (N) inputs to grassland soils for these organic materials. Compared to control treatments, cumulative CO2C efflux and the concentration of DOC increased significantly after WD and SD application, although only within the low nutrient soil. Both Cmicro and the fungal‐to‐bacterial ratio increased significantly following SD application, regardless of the initial soil nutrient content. These observations are likely to reflect the larger input of C, alongside the dominance of more strongly lignified compounds, associated with SD compared to WD to achieve a constant N application rate. Our results also indicate that the two digestate fractions generated significantly different CUE. The application of SD led to increases in Cmicro and positive values of CUE, whereas decreases in Cmicro and negative values of CUE were observed following WD application. These findings emphasize the need to carefully plan the management of digestate in agricultural production systems, to minimize negative impacts on C storage within soils whilst maximizing the agronomic value derived from digestate.

The enhancement of phenanthrene catabolism in soils amended with lignocellulosic waste material (spent brewery grains) was investigated. The soils were pre-treated with five white-rot fungi (Phanerochaete chrysosporium, Trametes versicolor, Irpex lateus, Pleurotus ostreatus, and Bjerkandera adusta). The changes in the kinetics of 14C-phenanthrene mineralisation (lag phases, the fastest rates and the overall extents) were measured in the inoculated, PAH-amended soils over time (1–100 d). Changes in the ligninolytic (laccase, lignin peroxidase and manganese peroxidase) and non-ligninolytic (β-glucosidase and phosphatase) enzymatic activities were also assessed. Overall results revealed that the amendment of fungal pre-treated SBG influenced the kinetics of mineralisation of 14C-phenanthrene as well as the enzymatic activities in soils. Soil inoculated with fungal pre-treated SBG caused reductions in lag phases as well as higher rates and extents of 14C-phenanthrene mineralisation in the following trend T. versicolor > B. adusta > P. chrysosporium = P. ostreatus > I. lateus. Furthermore, the extents of mineralisation generally reduced as levels of ligninolytic enzyme decreased, while the non-ligninolytic enzymes increased with soil-PAH contact time in all amendment conditions. These findings provided an insight on the potential of biological pre-treatment of waste materials for enhanced carbon, energy and nutrients on the bioactivities and biodegradation of organic pollutants which may be applicable during in situ remediations of contaminated soil.

Background Endovascular management of type B aortic dissection has been well established and accepted in the community. However, due to the lack of information on long-term outcome, endovascular management remains controversial in the setting of connective tissue disorders such as Marfan syndrome. Although surgical repair is recommended in type B aortic dissection with connective tissue disorders, recent studies demonstrated both feasibility and safety of endovascular interventions in those patients at least short term. Purpose Single centre experience and documentation of long-term outcomes after endovascular management of aortic conditions in patients with connective tissue disorders. Methods All patients with genetic confirmation of connective tissue disorders who underwent endovascular repair of the thoracic aorta were identified and evaluated retrospectively. Perioperative, procedure-specific and follow-up data were extracted from medical records of a structured surveillance program. Results Between 2002 and 2020, 18 patients were identified having undergone TEVAR procedures and protocol follow-up. The median age was 35.5 (IQL 30.0 – 42.7), and 12 (66.7%) were males; median ACEF II score was 0.6 (IQL 0.5 – 0.925). This cohort comprised 15 (83.3%) patients with genetically confirmed Marfan syndrome, two (11.1%) with Loeys-Dietz, and one (5.6%) with Ehlers-Danlos syndrome. Of these, 13 (72.2%) patients had undergone aortic root or aortic root/ascending aorta replacement independently in the past. The indication for a TEVAR procedure was seen in one case for degenerative aneurysmal disease (5.6%), in one case for elephant trunk stenosis (5.6%), in five cases for residual aortic dissection (27.8%), and in 11 cases for new type B dissection (61.1%). The most frequently used stent-graft was Valiant™ (Medtronic) in 10 cases (55.6%), followed by TAG® (Gore®) in four cases (22.2%), Zenith® (COOK®) in two cases (11.1%), and for Relay® (Bolton) and Sinus-XL® (Optimed) in one case each (5.6%). The average total covered length was 192.2±40.2 mm. Median follow-up duration was 77.5 months (IQR 35.8 - 131); three (16.7%) cases revealed failure of TEVAR and led to conversion to open surgery. Two patients (11.1%) had died including one patient in the perioperative phase. At the last follow-up, complete thrombosis of the false lumen was observed in 14 cases (82.3%), and 15 cases (88.2%) showed no aortic expansion or progression during the follow-up period resulting in an overall endovascular success rate of 72.2%. Conclusion Thoracic endovascular aortic repair can be performed for selected patients with connective tissue disorders at relatively low long-term mortality and morbidity. With improved devices and technical skills, mid- and long-term surveillance revealed promising outcomes and a low rate of aneurysmal degeneration. Structured surveillance remains crucial to detect emerging late complications and to accumulate more long-term data. Funding Acknowledgement Type of funding sources: None.

7 páginas.- 1 figura.- 3 tablas.- 47 referencias.- Supplementary data to this article can be found online athttps://doi.org/10.1016/j.scitotenv.2021.150025, There is a strong need for certified reference materials in the quality assurance of nonionic soil contaminant bioavailability estimations through physicochemical methods. We applied desorption extraction, a method recently standardized as ISO16751, to determine the bioavailable concentration of the most commonly regulated polycyclic aromatic hydrocarbon (PAH), benzo(a)pyrene (BaP), in the reference industrial soil BCR-524 with a certified BaP total concentration of 8.60 mg kg−1. This concentration represented BaP levels found in many PAH-polluted soils. The method, based on single-point extraction of the analyte desorbed into the aqueous phase by a receiving phase (Tenax or cyclodextrin), was applied ten times. The data fulfilled highly demanding quality criteria based on recovery and repeatability. The bioavailable BaP concentration detected through Tenax extraction, 1.82 mg kg−1, was comparable to bioavailable concentrations determined in field-contaminated soils and to environmental quality standards based on previously observed total BaP concentrations. There was good agreement (Student's t-test, P ≤ 0.05) with the bioavailable BaP concentration determined by cyclodextrin extraction (1.53 mg kg−1). The methods were extended to four other certified 4- and 5-ringed PAHs for comparative purposes. We suggest ways of improving of the ISO16751 standard related to further systematic assessment of the Tenax-to-soil ratio and incorporation of mass balances. Furthermore, BCR-524 is suitable for quality-assurance protocols with these methods when used in site-specific risk assessments of PAH-polluted environments., We would like to thank the Spanish Ministries of Economy and Competitiveness (CGL2016-77497-R) and Science and Innovation (PID2019-109700RB-C21) for supporting this work.

Polycyclic aromatic hydrocarbons (PAHs), the nitrogen-containing analogues (N-PAHs) and lead 210 (210Pb) were measured in 2-cm interval core segments from Bodo Creek to evaluate impact of oil pollution in the waterbody. PAHs and N-PAHs were measured by gas chromatography analysis with mass spectrometry detection, and 210Pb activity concentration was determined by alpha spectrometry measurement. Data shows that ƩPAHs and ƩN-PAHs ranged from 12,774.3–18,470.2 µg/kg and 524.0–672.2 µg/kg, respectively. Concentrations were found to increase with increase in depth (cm). Petrogenic PAHs predominated the surface sediment (with elevated levels of 2,3,6-trimethyl-naphthalene, phenanthrene and 1-methyl-phenanthrene), while pyrogenic-PAHs dominated the deeper segments (with high levels of pyrene, benzo[a]anthracene, chrysene and benzo[k]fluoranthene). For N-PAHs, benzo[h]quinoline, 4,7-phenanthroline and benzo[a]acridine recorded high values. Chemicals comparison with values measured from Bonny Estuary revealed greater PAHs contamination in the estuary, while N-PAHs recorded elevated values in the creek. 210Pb activity concentration in the creek showed relatively low activity compared to the estuary, and similar distribution with the aromatic hydrocarbons. The measured hydrocarbons were high and exceeded the Canadian sediment quality guidelines. However, there are concerns over toxic ratios > 70% and radioactivity (EPR-D-values) > 3 – 4.E ± 01 Bq measured in the polluted creek. This gives insight on the level of radioactivity, PAHs, N-PAHs and PAHs toxic ratios in Bodo creek which would be useful in future remediation studies and/or monitoring the ability of sediments to recover under natural conditions.

The present study combined two nutrient management strategies to improve the marketability of a waste-derived fertilizer: (a) isolation of ammoniacal nitrogen and (b) preparation of a bulk soil amendment. The wood fly ash with low content of pollutants was added to an agrowaste anaerobic digestate as alkaline stabilizer, which promoted the volatilization of ammonia and adsorption processes, and as nutrient supplement. The 39.71 ± 1.44 g blend was incubated for 60 hours at 20°C and 100 rpm in a closed chamber (250-mL Schott Duran® bottle) with a 5.21 ± 0.10 mL sulfuric acid trap of 10 different concentrations (0.11, 0.21, 0.32, 0.43, 0.54, 0.64, 0.75, 0.86, 0.96, and 1.07 mol/L). For analytical purposes, the sulfuric acid, water-soluble, and water-insoluble fractions of the blend were isolated after the incubation. The 1.07 mol/L sulfuric acid solution contained 23.69 ± 5.72 % more of ammonical nitrogen than the 0.11 mol/L solutions. However, in all cases the amount of nitrogen in the H2SO4 compartment was lower than the one in the water-soluble and water-insoluble fractions. Only the 15.52 ± 2.13 % of the nitrogen accounted after the incubation was found in the H2SO4 trap. The bottleneck of the NH3 stripping process was the rate of mass transfer at the interface between the blended fertilizer and the headspace of the closed chamber. The organic phosphorus was more susceptible to be adsorbed during the alkaline treatment with non-intrusive acidification than the nitrogen and carbon. Activation of the ash as adsorbent before mixing with the digestate should improve the properties of the blend as slow release fertilizer, since more nutrients would end in the water-insoluble fraction.

The addition of wood fly ash to an agrowaste anaerobic digestate has been proposed for improving the carbon to nutrient ratio of the soil organic amendment (C/N/P < 100/10/1). The ash-based treatment also aimed to improve properties of the anaerobic digestate as controlled-release fertilizer by decreasing the availability of nitrogen, carbon, and phosphorus. Treated (39.86 ± 0.94 g) and untreated (33.51 ± 0.84 g) digestates were incubated for 7 h at 20 °C and 100 rpm, in a 250-mL chamber with a 0.11 M sulfuric acid trap of 4.38 ± 0.02 mL. By the end of the incubation, the blend of 13.12 ± 2.87% ash and 86.88 ± 2.87% digestate released 8.95 ± 2.19 times more ammonia than the digestate alone. This was in agreement with the lower content of water-soluble ammoniacal nitrogen in the treated digestate (93.35 ± 21.00 mg/kg) than in the digestate incubated without the addition of the ash (357.64 ± 54.10 mg/kg). As per the very low levels of water-soluble nitric nitrogen found in the treated (0.16 ± 0.05 mg/kg) and the untreated (0.06 ± 0.02 mg/kg) digestate, the emissions of nitrous oxide were discarded. The availability of carbon increased 1.43 ± 0.82 times and the availability of phosphorus decreased approximately 100 times due to the addition of the ash to the digestate. The ash-based treatment was successful in improving the C/N/P of the digestate from 121.51 ± 57.18/9.94 ± 4.21/1 to 42.05 ± 9.88/2.48 ± 0.58/1.

Handling of food waste and agro-industrial waste digestates, and fly and bottom wood ashes represents an economic and environmental problem for society and industries where they are produced due to the requirement of large capacity storage facilities with special conditions. Since both materials contain important nutrients for crops, two different blending combinations were examined as potential slow-release fertilizers to enhance the circular economy. High share of biomass ashes were selected aiming the chemical alkaline stabilization of the digestates. The concentrations of nitrogen, carbon, and phosphorus in the water-soluble extract of the blends, which was obtained by adding ten parts of milli-Q® per each part of sample and subsequent solid–liquid separation, were measured during a 10-h incubation at 22 °C and 100 rpm. The volatilization of ammonia was the main route of losing nitrogen, with the greatest rate of volatilization at the time of blending and approximately 50 mg NH3-N/kg blend/hour by the end of the incubation. The hydrolysis taking place at alkaline pH was found responsible of the conversion of organic nitrogen to ammoniacal nitrogen and of the increase of the amount of water-soluble carbon, which rose progressively during the incubation. The release of CO2 was prevented by the high pH (> 10) of the blends. The drop in the concentration of water-soluble orthophosphate at the time of preparing the mixtures was driven by adsorption onto the ashes. The desorption of some of the orthophosphate was found to be inversely related to the amount of ashes added to the digestates. Graphic Abstract

This study investigated the extractability, bioaccessibility and biodegradation of 14C-phenanthrene and 14C-octacosane in two soils from former oil refinery facilities over 341 days. The impact of biostimulation and bioaugmentation treatments was also evaluated. At 0, 31, 62, 124 and 341 days, the loss and extractability (using dichloromethane, methanol:water and hydroxypropyl-β-cyclodextrin (HPCD)) of the 14C-hydrocarbons were measured. Further at each time point, the mineralisation of the 14C-hydrocarbons was measured respirometrically under the different conditions. In general, extractions with methanol: water and HPCD were similar for both hydrocarbons in the different treatments; however, these values were less that those measured with DCM. Overall, significantly higher (p ≤ 0.05) amounts of 14C-phenanthrene were lost, readily extracted and mineralised in the soils, with treatments having little impact upon the degradation of this hydrocarbon over 341 days. Conversely, bioaugmentation significantly increased the loss of 14C-octacosane residues from soils and sustained degradation after 31 days. Surprisingly, HPCD and methanol:water both under-predicted the extent to which the contaminants were degraded at each time point. Determining the likelihood of effective biodegradation by the stimulation of indigenous microorganisms or through bioaugmentation needs to be assessed by both chemical and biological measurements of bioaccessibility, rather than just by that which is totally extractable from soil. However, soils which have high loadings of organic matter and/or organic contaminants may prevent accurate assessment of contaminant bioaccessibility, as measured by HPCD.

Fluorene, a low molecular weight polycyclic aromatic hydrocarbon (PAH), is of immense environmental interest because of its carcinogenicity, teratogenicity, mutagenicity, toxicity and persistence to microbial degradation. Existentially, there is paucity of information on PAH degradation by fungi isolated from marine environment. Therefore, this study investigated fluorene degradation efficiency of marine derived filamentous fungus, Mucor irregularis strain bpo1 (GenBank Accession Number: MK373020). Response Surface Methodology (RSM) using Box–Behnken Design (BBD) was successfully deployed in the optimization of process parameters (pH-7, temperature-32.5 °C, substrate concentration-100 mg L−1 and dry weight-2 g) resulting in 81.50% fluorene degradation on 5th day. The design and regression model were found to be statistically significant, adequate and appropriate with p < 0.0001, F value = 202.39, and predicted coefficient of determination (R2 = 0.9991). Optimization of the vital constituents of the mineral salt medium (MSM) used for the study using RSM-Central Composite Design (CCD) resulted in 79.80% fluorene degradation rate. Enhanced fluorene degradation efficiency (82.50%) was recorded when the optimized process variables were subjected to growth-linked validation experiments. The enzyme activities revealed 87%, 59% and 31% induction of laccase, manganese peroxidase and lignin peroxidase respectively. Four metabolites; 9H-fluoren-9-one, benzene-1,2-dicarboxylic acid, 2-hydroxybenzoic acid and phenol obtained after the experiment were characterized and confirmed with GC-MS analysis. The findings revealed the promising potentials of M. irregularis in PAH degradation and by extension green remediation technology. © 2020 The Authors

The indiscriminate disposal of olsalazine in the environment poses a threat to human health and natural ecosystems because of its cytotoxic and genotoxic nature. In the present study, degradation efficiency of olsalazine by the marine-derived fungus, Aspergillus aculeatus (MT492456) was investigated. Optimization of physicochemical parameters (pH. Temperature, Dry weight) and redox mediators {(2,20-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), p-Coumaric acid and 1-hydroxybenzotriazole (HOBT)} was achieved with Response Surface Methodology (RSM)-Box-Behnken Design (BBD) resulting in 89.43% removal of olsalazine on 7th day. The second-order polynomial regression model was found to be statistically significant, adequate and fit with p

Trace-level plutonium in the environment often comprises local and global contributions, and is usually anthropogenic in origin. Here, we report estimates of local and global contributions to trace-level plutonium in soil from a former, fast-breeder reactor site. The measured 240Pu/239Pu ratio is anomalously low, as per the reduced 240Pu yield expected in plutonium bred with fast neutrons. Anomalies in plutonium concentration and isotopic ratio suggest forensic insight into specific activities on site, such as clean-up or structural change. Local and global 239Pu contributions on-site are estimated at (34 ± 1)% and (66 ± 3)%, respectively, with mass concentrations of (183 ± 6) fg g−1 and (362 ± 13) fg g−1. The latter is consistent with levels at undisturbed and distant sites, (384 ± 44) fg g−1, where no local contribution is expected. The 240Pu/239Pu ratio for site-derived material is estimated at 0.05 ± 0.04. Our study demonstrates the multi-faceted potential of trace plutonium assay to inform clean-up strategies of fast breeder legacies., Nature Communications, 12 (1), ISSN:2041-1723

Polycyclic aromatic compounds (PACs) pollution has been the focus of environmental research, mostly due to their mutagenicity, carcinogenicity, teratogenicity and genotoxicity. Concentrations of polycyclic aromatic hydrocarbons (PAHs) and the nitrogen-containing analogues (N-PAHs) (which tend to accumulate in sediments rather than water) was measured in 2 cm intervals segments from Bonny Estuary, Niger Delta using GC–MS. Data showed that PAHs/N-PAHs levels ranged from 8699 to 22,528 µg/kg and 503–2020 µg/kg, respectively. Furthermore, the data revealed that ƩPAHs level in the estuarine segments was > 45% higher than DPR/EGASPIN intervention limit. This gives insight on PAHs/N-PAHs contamination in the oil rich region.

The impact of whole digestate (WD) and its fractions (solid [SD] and liquid [LD]) on 14C-phenanthrene mineralization in soil over 90 d contact time was investigated. The 14C-phenanthrene spiked soil was aged for 1, 30, 60 and 90 d. Analysis of water-soluble nitrogen, phosphorus, total (organic and inorganic) carbon, and quantitative bacterial count were conducted at each time point to assess their impact on mineralization of 14C-phenanthrene in soils. Indigenous catabolic activity (total extents, maximum rates and lag phases) of 14C-phenanthrene mineralization were measured using respirometric soil slurry assay. The soil amended with WD outperformed the SD and LD fractions as well as showed a shorter lag phase, higher rate and extent of mineralization throughout the study. The digestates improved (P < 0.05) the microbial population and nutritive content of the soil. However, findings showed that spiking soil with phenanthrene generally reduced the growth of microbial populations from 1 to 90 d and gave a lower nutritive content in comparison with the non-spiked soil. Also, soil fertility and bacteria count were major factors driving 14C-phenanthrene mineralization. Particularly, the non-phenanthrene degraders positively influenced the cumulative mineralization of 14C-phenanthrene after 60 d incubation. Therefore, the digestates (residue from anaerobic digestion) especially WD, which enhanced 14C-phenanthrene mineralization of the soil without minimal basal salts medium nor additional degraders should be further exploited for sustainable bioremediation of PAHs contaminated soil.

Improving risk assessment and remediation rests on better understanding of contaminant bioavailability. Despite their strong toxicological attributes, little is known about the partitioning behaviour and bioavailability of polar polycyclic aromatic hydrocarbons (PAHs) in aquatic environments. The present study provides an insight into the bioavailable fractions of polar PAHs and their parent analogues in the tissues of the Sydney rock oyster, Saccostrea glomerata, a model aquatic bio-indicator organism. The concentration and distribution patterns of parent and polar PAHs including oxygenated PAHs (oxyPAHs), nitrated PAHs (NPAHs) and heterocyclic PAHs (HPAHs) were determined in water, sediment and oysters from an ecologically and economically important estuary of New South Wales, Australia. Total concentrations of PAHs, oxyPAHs, NPAHs and HPAHs were higher in sediments compared to oyster tissue and water. For most polar PAHs, total concentrations for water, sediment and oyster samples were1 μg/g (μg/l for water) while parent PAH concentrations were several orders of magnitude higher. Computed biota-sediment accumulation factors (BSAFs) on lipid-normalized oyster concentrations revealed that while ∑oxyPAHs and ∑HPAHs exhibited low accumulation from sediment to oyster tissues (BSAF1), ∑PAHs and ∑NPAH were found to be accumulated at high levels (BSAF1). BSAF individual computation showed that bioaccumulation of nine investigated HPAHs in oyster tissues were relatively low and only 2-EAQ (oxyPAH) and 1N-NAP (NPAH) showed high levels of accumulation in oyster tissues, similar to parent PAHs. To the best of our knowledge, this is the first known study on the bioavailability of polar and non-polar PAHs in an Australian aquatic environment. The outcome of this study might be a useful indicator of the potential risks of polar PAHs to humans and other living organisms.

The environmental and health risks associated with "nonextractable" residues (NERs) of polycyclic aromatic hydrocarbons in soils and their potential for remobilization remain largely unexplored. In this novel study, sequential solvent extractions were employed to interrogate time-dependent remobilization of benzo[a]pyrene (B[a]P) NERs and associated kinetics after re-equilibration (REQ) periods lasting 30 d in four artificially spiked soils aged for up to 200 days. Following sequential extractions of the re-equilibrated soils, remobilization of B[a]P NERs was observed and further confirmed by decreases in the absolute amounts of B[a]P recovered following methanolic saponification after REQ. Remobilization may occur through slow intercompartmental partitioning of more sequestered into less sequestered B[a]P fractions in soils. The amounts of B[a]P remobilized in soils decreased throughout aging following first-order kinetics, and the rates of decrease were slow but 2 to 4 times faster than those of extractable B[a]P before re-equilibration. Sandy-clay-loam soils with large amounts of hard organic carbon exhibited less NER remobilization compared to sandy soils. The amounts of remobilized B[a]P decreased significantly ( p < 0.05) with aging. Specifically, butanol-remobilized B[a]P in soils spiked at 10 mg/kg and 50 mg/kg B[a]P ranged from 0.15 to 0.39 mg/kg and 0.67 to 2.30 mg/kg, respectively, after 200 d of aging.

Plant-assisted biodegradation can offer a cost-effective and sustainable approach for the bioremediation of PAHs in soil. As such, selecting the most appropriate plant species is important. The potential for plant-assisted biodegradation of complex PAH-diesel mixtures in soil by sorghum (Sorghum bicolor) and alfalfa (Medicago sativa) grown as monocultures and mixed cultures using 14C-contaminants has not been widely reported. The objective of this study was to assess 14C-phenanthrene mineralisation profiles in mixtures of PAH-diesel in soil in the presence of Sorghum bicolor and Medicago sativa. Soil was spiked with PAHs and diesel, after which M. sativa and S. bicolor were introduced and grown as mono- or mixed- cultures. The toxicity of the PAH-diesel oil mixture in the planted treatments, as well as its effect on the mineralisation of 14C-phenanthrene were evaluated. Monocultures of both plant species tolerated the complex PAH-diesel mixtures based on growth and survival, and increased rates and extents of 14C-phenanthrene mineralisation in soil. The influence of PAH concentration on 14C-phenanthrene mineralisation profiles varied in planted and unplanted treatments. The rates and extents of 14C-phenanthrene mineralisation tended to decrease in diesel amended soil, especially at low PAH concentrations. To the best of the authors’ knowledge, this is the first report of 14C-phenanthrene mineralisation patterns in complex PAH-diesel oil mixtures contaminated soil especially with respect to the specified plant species. The findings offer new insights on mono- and multi-species phytotoxicity as well as plant-assisted biodegradation of PAH mixtures in soil which may be useful in the risk assessment and remediation of contaminated sites.

The Niger Delta is one of the largest oil producing regions of the world. Large numbers and volumes of oil spills have been reported in this region. What has not been quantified is the putative exposure of humans and/or the environment to this hydrocarbon pollution. In this novel study, advanced geostatistical techniques were applied to an extensive database of oil spill incidents from 2007 to 2015. The aims were to (i) identify and analyse spill hotspots along the oil pipeline network and (ii) estimate the exposure of the hydrocarbon pollution to the human population and the environment within the Niger Delta. Over the study period almost 90millionlitres of oil were released. Approximately 29% of the human population living in proximity to the pipeline network has been potentially exposed to oil contamination, of which 565,000 people live within high or very high spill intensity sectors. Over 1000km2 of land has been contaminated by oil pollution, with broadleaved forest, mangroves and agricultural land the most heavily impacted land cover types. Proximity to the coast, roads and cities are the strongest spatial factors contributing to spill occurrence, which largely determine the accessibility of sites for pipeline sabotage and oil theft. Overall, the findings demonstrate the high levels of environmental and human exposure to hydrocarbon pollutants in the Niger Delta. These results provide evidence with which to spatially target interventions to reduce future spill incidents and mitigate the impacts of previous spills on human communities and ecosystem health. Keywords: Oil pipelines, Sabotage, Oil spills, Pollution hotspots, Risk assessment, Health

This study investigated the use of a hydrophobic resin, amberlite XAD, as a tool for assessing the biodegradation potential of 14C-phenanthrene in soil. The method was optimised in terms of soil/XAD ratio, shaking, extraction time and eluting solvent. The most effective method was then tested on selected XADs, and the performance compared with cyclodextrin (HP- β -CD) and dichloromethane (DCM) extractions suitability to predict phenanthrene biodegradation in soil over 100 d. Results showed that the optimum conditions for the XAD extraction technique are a 2:1 soil/XAD ratio, 100 rpm mixing for 22 h and elution using a DCM:methanol solution (1:1). Mineralisation of 14C-phenanthrene was accurately predicted by HP- β -CD ( r 2 = 0 . 990 , slope = 0.953, intercept = 1.374) and XAD-4 extractions ( r 2 = 0 . 989 , slope = 0.820, intercept = 6.567), while DCM overestimated the bioaccessibility of 14C-phenanthrene ( r 2 = 0 . 999 , slope = 1.328, intercept = − 49 . 507 ). This investigation showed that XAD extraction can be considered a suitable non-exhaustive technique for estimating biodegradability of phenanthrene in soil.

Pathways for replacing chemical fertilisers (reliant on rock P resources) with alternative P-bearing materials require assessment of soil processes, crop nutrient acquisition and potential pollution consequences. We examined bioenergy waste materials, individually and as combined ash and anaerobic digestate in terms of plant P availability and mobility. We compared initial effects on mixing of amendments with a test soil and effects after 6-weeks pot trials, with and without wheat growth, against soil and chemical fertiliser controls. Chemical extractions, 31P NMR spectroscopic determination of P forms and phytase-labile P assays examined processes of P release. 31P NMR analysis revealed that ash comprised dominantly inorganic orthophosphate P with inherent low P solubility. Initial ash mixing with soils increased solution pH, soluble P in water (pure ash alone) and in citrate (ash alone and in blends). Digestate comprised a diverse array of orthophosphate and organically-complexed P forms, similar to the test soil P compositions, with limited P solubility on initial mixing. Following no plant incubations high water-soluble P with ash additions remained but all effects on citrate-soluble P were normalised. Incubations with plants increased water-soluble P in digestate only and blended amendment treatments relative to initial mixing. When comparing to chemical fertiliser the digestate plus ash blends led to smaller water-soluble P, but equal P in above-ground biomass after incubation. The ash-digestate C:N:P ratios and P form diversity appeared to promote microbial regulation of plant P availability versus potential leaching. The results suggest that the initial days-months are important periods for amendment interactions with soils during plant establishment and the lag before strong growth when system P mobility may induce polluted runoff. Biogeochemical P solubility controls require further study across differing soils and timescales to inform management of bioenergy wastes as fertilisers, particularly in terms of trade-offs such as crop nutrition versus system P losses.

In this study, the thermal stability of a wood shaving biochar (WS, 650 °C), a chicken litter biochar (CL, 550 °C) and an activated carbon (AC, 1100 °C) were evaluated by combustion at 375 °C for 24 h to remove the labile non-carbonized organic matter. Results showed that WS and CL biochars were not thermally stable and can lose most of the organic C during combustion. The combusted WS and CL biochars retained considerable amounts of negative charge and displayed higher sorption for Cd (from 5.46 to 68.9 mg/g for WS and from 48.5 to 60.9 mg/g for CL). The AC retained 76.5% of its original C and became more negatively chargely after combustion, but its sorption for Cd slightly decreased (from 18.5 to 14.9 mg/g). This study indicated that after potential burning in wildfires (200–500 °C), biochars could have higher sorption capacity for metals by remaining minerals.

In this study, an acidic biochar and a neutral biochar were applied at 5 wt% into two soils for an 11-month incubation experiment. One Ferrosol soil (Ba) was slightly acidic with low organic matter and the other Dermosol soil (Mt) was slightly alkaline with high organic matter. The acidic (pH = 3.25) wood shaving (WS) biochar had no marked impact on nutrient levels, cation exchange capacity (CEC), pH and acid neutralization capacity (ANC) of either soil. By contrast, the neutral (pH = 7.00) chicken litter (CL) biochar significantly increased major soluble nutrients, pH, ANC of soil Ba. In terms of C storage, 87.9% and 69.5% WS biochar-C can be sequestrated as TOC by soil Ba and Mt, respectively, whereas only 24.0% of CL biochar-C stored in soil Ba and negligible amount in Mt as TOC. Biochars did not have significant effects on soil sorption capacity and sorption reversibility except that CL biochar increased sorption of soil Ba by around 25.4% and decreased desorption by around 50.0%. Overall, the studied acidic C rich WS biochar held little agricultural or remedial values but was favourable for C sequestration. The neutral mineral rich CL biochar may provide short-term agricultural benefit and certain sorption capacities of lower sorption capacity soils, but may be unlikely to result in heightened C sequestration in soils. This is the first study comprehensively examining functions of acidic and neutral biochars for their benefits as a soil amendment and suggests the importance of pre-testing biochars for target purposes prior to their large scale production. Refereed/Peer-reviewed