Tropical peatlands are important carbon stores that are vulnerable to drainage and conversion to agriculture. Protection and restoration of peatlands are increasingly recognised as key nature based ...solutions that can be implemented as part of climate change mitigation. Identification of peatland areas that are important for protection and restauration with regards to the state of their carbon stocks, are therefore vital for policy makers. In this paper we combined organic geochemical analysis by Rock-Eval (6) pyrolysis of peat collected from sites with different land management history and optical remote sensing products to assess if remotely sensed data could be used to predict peat conditions and carbon storage. The study used the North Selangor Peat Swamp forest, Malaysia, as the model system. Across the sampling sites the carbon stocks in the below ground peat was ca 12 times higher than the forest (median carbon stock held in ground vegetation 114.70 Mg ha-1 and peat soil 1401.51 Mg ha-1). Peat core sub-samples and litter collected from Fire Affected, Disturbed Forest, and Managed Recovery locations (i.e. disturbed sites) had different decomposition profiles than Central Forest sites. The Rock-Eval pyrolysis of the upper peat profiles showed that surface peat layers at Fire Affected, Disturbed Forest, and Managed Recovery locations had lower immature organic matter index (I-index) values (average I-index range in upper section 0.15 to -0.06) and higher refractory organic matter index (R -index) (average R-index range in upper section 0.51 to 0.65) compared to Central Forest sites indicating enhanced decomposition of the surface peat. In the top 50 cm section of the peat profile, carbon stocks were negatively related to the normalised burns ratio (NBR) (a satellite derived parameter) (Spearman's rho = -0.664, S = 366, p-value = <0.05) while there was a positive relationship between the hydrogen index and the normalised burns ratio profile (Spearman's rho = 0.7, S = 66, p-value = <0.05) suggesting that this remotely sensed product is able to detect degradation of peat in the upper peat profile. We conclude that the NBR can be used to identify degraded peatland areas and to support identification of areas for conversation and restoration.
Exploration for shale gas occurs in onshore basins, with two approaches used to predict the maximum gas in place (GIP) in the absence of production data. The first estimates adsorbed plus free gas ...held within pore space, and the second measures gas yields from laboratory pyrolysis experiments on core samples. Here we show the use of sequential high-pressure water pyrolysis (HPWP) to replicate petroleum generation and expulsion in uplifted onshore basins. Compared to anhydrous pyrolysis where oil expulsion is limited, gas yields are much lower, and the gas at high maturity is dry, consistent with actual shales. Gas yields from HPWP of UK Bowland Shales are comparable with those from degassed cores, with the ca. 1% porosity sufficient to accommodate the gas generated. Extrapolating our findings to the whole Bowland Shale, the maximum GIP equate to potentially economically recoverable reserves of less than 10 years of current UK gas consumption.
•London soil PAH concentrations are comparable with other cities.•London soil PCB concentrations are higher than other cities.•London soils contain multiple pryrogenic PAH sources.•Normal background ...PAH concentrations exceed land management assessment criteria.
Surface soils from a 19km2 area in east London, UK were analysed for polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) (n=76). ∑16 PAH ranged from 4 to 67mg/kg (mean, 18mg/kg) and ∑50 PAH ranged from 6 to 88mg/kg (mean, 25mg/kg). ∑7 PCB ranged from 1 to 750μg/kg (mean, 22μg/kg) and ∑tri-hepta PCB ranged 9 to 2600μg/kg (mean, 120μg/kg). Compared to other international cities concentrations were similar for PAH but higher for PCB. Normal background concentrations (NBC) were calculated and compared to risk-based human health generic assessment criteria (GAC). Benzoapyrene NBC for urban (6.9mg/kg), semi-urban (4.4mg/kg) and urban+semi urban (6mg/kg) domains exceed residential (1mg/kg) and allotment (2.2mg/kg) LQM/CIEH GAC (at 6% SOM) and the Indeno1,2,3-cdpyrene NBC for urban (6.8mg/kg) and urban+semi-urban (5.2mg/kg) domains exceed the residential (4.2mg/kg) LQM/CIEH GAC (at 6% SOM).
Capsule Abstract: Normal background concentrations of polycyclic aromatic hydrocarbons and polychlorinated biphenyls are elevated in east London soils and in some cases exceed regulatory assessment criteria.
Abstract
Gas storage and recovery processes in shales critically depend on nano-scale porosity and chemical composition, but information about the nanoscale pore geometry and connectivity of kerogen, ...insoluble organic shale matter, is largely unavailable. Using adsorption microcalorimetry, we show that once strong adsorption sites within nanoscale network are taken, gas adsorption even at very low pressure is governed by pore width rather than chemical composition. A combination of focused ion beam with scanning electron microscopy and transmission electron microscopy reveal the nanoscale structure of kerogen includes not only the ubiquitous amorphous phase but also highly graphitized sheets, fiber- and onion-like structures creating nanoscale voids accessible for gas sorption. Nanoscale structures bridge the current gap between molecular size and macropore scale in existing models for kerogen, thus allowing accurate prediction of gas sorption, storage and diffusion properties in shales.
Surface sediment samples (n = 45) were collected along a 110 km transect of the river Thames in October 2011, starting from Teddington Lock out through the industrial area of London to the southern ...North Sea. Several legacy and novel brominated flame retardants (NBFRs) were analysed, including 13 polybrominated diphenyl ethers (PBDEs) (congeners 17, 28, 47, 99, 100, 153, 154, 183, 196, 197, 206, 207 and 209), hexabromocyclododecane (HBCDDs), tetrabromobisphenol A (TBBPA), hexabromobenzene (HBB), 2,4,6-tribromophenol (TBP), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EH-TBB or TBB), bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP or TBPH), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), pentabromoethylbenzene (PBEB), anti/syn-dechlorane plus (a/s-DP), 2,2′,4,4′,5,5′-hexabromobiphenyl (BB153) and α-,β-1,2-dibromo-4-(1,2-dibromoethyl) cyclohexane (α-,β-DBE-DBCH or TBECH). A novel analysis method based on liquid chromatographic separation, followed by high resolution accurate mass detection using the Orbitrap platform was used for quantification. Results revealed that BDE-209 had the highest concentrations (<0.1 to 540 μg kg−1 dw) and detection frequency, accounting for 95% of all PBDE congeners measured. Indicative evidence of debromination of the PentaBDE technical mixture was observed through elevated relative abundance of BDE-28 in sediment compared to the Penta-BDE formulation. NBFRs were detected at comparable levels to PBDEs (excluding BDE-209), which indicates increasing use of the former. Spatial trend analysis showed that samples from industrial areas had significantly higher concentrations of Σ12PBDEs, ΣHBCDDs, TBBPA, BEH-TEBP, BTBPE and TBP. Three locations showed high concentrations of HBCDDs with diastereomer patterns comparable to the technical mixture, which indicate recent input sources to the sediment.
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•BDE-209 dominant PBDE congener in sediments at 95% of total PBDE•Concentrations of some NBFRs detected match those of PBDEs (except BDE-209).•Σ12PBDEs, ΣHBCDDs, TBBPA, BEH-TEBP, BTBPE and TBP highest in the industrial area•Elevated HBCDD concentrations and distinct isomer pattern detected at 3 locations•Isomer pattern at these locations resembles commercial HBCDD formulation.
Ecosystem services provided by tropical peat swamp forests, such as carbon (C) storage and water regulation, are under threat due to encroachment and replacement of these natural forests by ...drainage-based agriculture, commonly oil palm plantation. This study aims to quantify how the chemical and physical properties of peat change during land conversion to oil palm. This will be addressed by comparing four separate stages of conversion; namely, secondary peat swamp forests, recently deeply drained secondary forests, cleared and recently planted oil palm, and mature oil palm plantation in North Selangor, Malaysia. Results indicate accelerated peat decomposition in surface peats of mature oil palm plantations due to the lowered water table and altered litter inputs associated with this land-use change. Surface organic matter content and peat C stocks at secondary forest sites were higher than at mature oil palm sites (e.g. C stocks were 975±151 and 497±157Mgha−1 at secondary forest and mature oil palm sites, respectively). Land conversion altered peat physical properties such as shear strength, bulk density and porosity, with mirrored changes above and below the water table. Our findings suggest close links between the organic matter and C content and peat physical properties through the entire depth of the peat profile. We have demonstrated that conversion from secondary peat swamp forest to mature oil palm plantation may seriously compromise C storage and, through its impact on peat physical properties, the water holding capacity in these peatlands.
•Peat chemical composition shows more enhanced organic matter decomposition in mature oil palm plantations than in forest sites.•Peat C stocks in mature oil palm plantations was half those at forest site.•Variation in peat organic matter and C content was related to changes peat shear strength, bulk density and water content.•Conversion from forest to oil palm compromise C storage and water holding capacity.
As a non-invasive imaging technique, this study explores the application of Computed Tomography (CT) in microplastics research, assessing its potential to distinguish different types and sizes of ...microplastics (polypropylene, polyethylene terephthalate, polyethylene, and polyvinyl chloride) from homogenised river-estuarine sediment. When examined in layers within artificial cores, all microplastic types could be observed by CT imagery, with good contrast in X-ray attenuation (based on image gray level intensity) against background sediments. Large microplastics (4 mm diameter) were also detectable when distributed randomly amongst the sediment. These spiked cores had sufficient difference in attenuation to allow segmentation between type, and therefore isolate individual microplastics. Due to limitations on scan resolution, smaller microplastics (≤125 μm diameter) could not be detected in spiked cores. Scans of two sediment cores from a Thames River tributary (UK) revealed two distinctive sediment structures which could influence microplastic accumulation. This information would be lost using conventional recovery procedures.
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•A new application of Computed Tomography (CT) in microplastics research is proposed.•CT scans reveal non-invasive study of microplastics in sediments could be possible.•Larger microplastics in artificial cores were digitally recovered and isolated.•Scans of environmental cores show data on sediment structure lost by other methods.
Nairobi River sediments from locations adjacent to the Kawangware and Kiambio slums were analyzed via Fourier transform ion cyclotron resonance mass spectrometry with atmospheric pressure ...photoionization (APPI-FT-ICR-MS). The data from these ultrahigh resolution, untargeted measurements provided new insights into the impacts of local anthropogenic activity, which included likely benzo- and dibenzothiophene pollution with a suspected petrogenic origin, and prominent surfactant-like compositions. Other features in the data included highly abundant tetra-oxygenated compounds, and oxygenated nitrogen compounds with sphingolipid interpretations. Most notably, several hydrocarbon and oxygenated compound classes in the sediment data featured intensity patterns consistent with steroid molecular formulas, including those associated with sewage contamination investigatory work. In support of this interpretation, standards of cholesterol, β-sitosterol, stigmasterol, coprostanol, cholestanol, and 5α-sitostanol were analyzed via APPI, to explore steroid ionization behavior. Generally, these analytes produced radical molecular ions (M•+), and water-loss pseudo molecular ion species (M-H2O•+ and M+H-H2O+), among various other less intense contributions. The absence of pseudo molecular protonated species (M+H+) was notable for these compounds, because these are often assumed to form with APPI. The standard measurements demonstrated how steroids can create the observed intensity patterns in FT-ICR-MS data, and hence these patterns have the potential to indicate sewage contamination in the analysis of other complex environmental samples. The steroid interpretation for the Kawangware and Kiambio data was further verified by subjecting the steroid standard radical molecular ions to collision-induced dissociation and comparing the detected fragments to those for the corresponding isolated ions from a Kawangware sediment sample.Nairobi River sediments from locations adjacent to the Kawangware and Kiambio slums were analyzed via Fourier transform ion cyclotron resonance mass spectrometry with atmospheric pressure photoionization (APPI-FT-ICR-MS). The data from these ultrahigh resolution, untargeted measurements provided new insights into the impacts of local anthropogenic activity, which included likely benzo- and dibenzothiophene pollution with a suspected petrogenic origin, and prominent surfactant-like compositions. Other features in the data included highly abundant tetra-oxygenated compounds, and oxygenated nitrogen compounds with sphingolipid interpretations. Most notably, several hydrocarbon and oxygenated compound classes in the sediment data featured intensity patterns consistent with steroid molecular formulas, including those associated with sewage contamination investigatory work. In support of this interpretation, standards of cholesterol, β-sitosterol, stigmasterol, coprostanol, cholestanol, and 5α-sitostanol were analyzed via APPI, to explore steroid ionization behavior. Generally, these analytes produced radical molecular ions (M•+), and water-loss pseudo molecular ion species (M-H2O•+ and M+H-H2O+), among various other less intense contributions. The absence of pseudo molecular protonated species (M+H+) was notable for these compounds, because these are often assumed to form with APPI. The standard measurements demonstrated how steroids can create the observed intensity patterns in FT-ICR-MS data, and hence these patterns have the potential to indicate sewage contamination in the analysis of other complex environmental samples. The steroid interpretation for the Kawangware and Kiambio data was further verified by subjecting the steroid standard radical molecular ions to collision-induced dissociation and comparing the detected fragments to those for the corresponding isolated ions from a Kawangware sediment sample.
An enhanced in vitro human dermal bioavailability method was developed to measure the release of twenty parent and seven alkylated high molecular weight (HMW) polycyclic aromatic hydrocarbons (PAHs) ...from contaminated soils collected from five former manufactured Gas Plants (MGP) in England. GC-MS/MS was used to quantify HMW PAHs in soil, Strat-M artificial membrane representing skin, and synthetic receptor solution (RS) representing systemic circulation at 1-h, 10-h, and 24-h timesteps. Fluoranthene and pyrene exhibited the highest fluxes from soils to membrane (ranging from 9.5 - 281 ng/cm2/h) and soil to RS (<LOQ to 16.9 ng/cm2/h). Chrysene, benzoaanthracene, benzobfluoranthene and the alkylated C1-fluoranthene/pyrene homologue series demonstrated fluxes higher than other HMW PAHs. The dermal fluxes were generally lower than those reported in previous investigations and suggests that dermal absorption varies between both HMW parent and alkylated PAHs and individual PAHs. The utilisation of real-world contaminated soils allowed for a more realistic representation; this is important because current risk assessment guidance is baseed on results from experiments that used artificially spiked soils. This research shows that the the ranges of dermal fluxes are PAH dependent and impact the mass of absorbed from soil after dermal exposure and therefore the potential risk contaminated soil poses to human health.
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•Conducted in vitro human dermal bioavailability experiments on 5 MGP soils.•Measured 20 parent and 7 alkylated HMW PAHs dermal fluxes.•Highest dermal fluxes measured for PAHs with fewer rings and lower alkylation.•Membranes acted as PAH sink for all HMW PAHs.•Alkylated C1-Fla/Pyr showed significant dermal flux at longer timesteps.
Soils sampled from 10 former manufactured gas plants (MGP) in the UK were investigated using gas chromatography mass spectrometry (GC-MS/MS) and Rock-Eval (6) Pyrolysis (RE). RE is a screening tool ...used to characterise bulk organic matter in soils via the release of carbon compounds during pyrolysis and oxidation. Both the distributions and concentrations of 30 parent and 21 alkylated polycyclic aromatic hydrocarbons (PAHs) and the parameters of RE were analysed to establish relationships between soils and the MGP processes history. Principal component analysis (PCA) using the PAHs distributions and RE parameters can assist with differentiating between MGP processes. MGP processes utilizing oil provided the clearest results, attributed to petrogenic signatures with high proportions of low molecular weight PAHs. Processes using lower temperature processes were distinguished by higher proportions of high molecular weight PAHs. RE parameters alone were unable to distinguish MGP processes but showed potential in estimating the lability and thus the amount of PAH that could be released from soils. This research provides new insights that may be useful in understanding and characterising the risks posed to human health from PAHs in soils.
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•GC-MS/MS measured distributions of 30 parent and 21 alkylated PAHs in MGP soils.•Rock-Eval (6) pyrolysis parameters S1, TpkS2, HI, OI and the R-index characterise OM.•MGP processes associated to oil contamination resulted in petrogenic signatures.•Low temperature MGP process had higher relative contributions of HMW PAHs.
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