Metal removal from contaminated effluents was examined following reaction with natural apatites of biological and geological origin or a synthetic hydroxylapatite (HAP). Mammalian meat and bone meal ...(MBM), a by-product from meat industry, was the biological apatite source. The effect of incineration on metal removal capacity of MBM and HAP was also examined. The reactivity of apatites for all tested metals (Pb, Cd, Cu and Zn) followed the general order: synthetic
>
biological
>
mineral. For all apatites tested, Pb was removed best and preferentially from multi-metal solutions. MBM and HAP (0.5 g solid) removed Pb completely from both highly concentrated single metal solutions (50 ml, 1000 mg/L Pb) and from multi-metal solutions (50 ml) with 100 mg/L each of Cd, Cu and Zn in addition to Pb. The incineration of MBM (725 °C and 850 °C) reduced significantly its capacity for removal of Zn (by 47%, from 56 mg/g to 9 mg/g) and Cd (by 38%, from 53 mg/g to 13 mg/g) in particular and to a lesser extent for Cu (by 14%, from 61 mg/g to 46 mg/g) while the removal of Pb was not affected (100 mg/g). The same pattern was observed for incinerated HAP. SEM and XRD analysis indicated that HAP reacted with the metals by precipitation of pure metal phosphates—Pb hydroxylapatite, Zn phosphate (hopeite), a Cd phosphate (identified only by ED-SEM) and Cu phosphate (libenthenite).
Abstract
Biochar production via biomass pyrolysis with subsequent burial in soils provides a carbon dioxide removal technology that is ready for implementation, yet uptake requires acceleration; ...notably, through generation of cost reductions and co-benefits. Here we find that biomass enrichment (doping) with refined minerals, mineral by-products, or ground rocks reduces carbon loss during pyrolysis, lowering carbon dioxide removal costs by 17% to US$ 80–150 t
−1
CO
2
, with 30% savings feasible at higher biomass costs. As a co-benefit, all three additives increase plant-available nutrient levels. Doping with potassium-bearing minerals can increase both potassium and phosphorus release. Mineral doping in biochar production therefore offers carbon dioxide removal at lower costs, while alleviating global phosphorus and potassium shortages. This makes it unique among carbon dioxide removal technologies.
Summary findings are presented from an investigation to improve understanding of the environmental risks associated with developing an unconventional-hydrocarbons industry in the UK. The EQUIPT4RISK ...project, funded by UK Research Councils, focused on investigations around Preston New Road (PNR), Fylde, Lancashire, and Kirby Misperton Site A (KMA), North Yorkshire, where operator licences to explore for shale gas by hydraulic fracturing (HF) were issued in 2016, although exploration only took place at PNR. EQUIPT4RISK considered atmospheric (greenhouse gases, air quality), water (groundwater quality) and solid-earth (seismicity) compartments to characterise and model local conditions and environmental responses to HF activities. Risk assessment was based on the source-pathway-receptor approach. Baseline monitoring of air around the two sites characterised the variability with meteorological conditions, and isotopic signatures were able to discriminate biogenic methane (cattle) from thermogenic (natural-gas) sources. Monitoring of a post-HF nitrogen-lift (well-cleaning) operation at PNR detected the release of atmospheric emissions of methane (4.2 ± 1.4 t CH4). Groundwater monitoring around KMA identified high baseline methane concentrations and detected ethane and propane at some locations. Dissolved methane was inferred from stable-isotopic evidence as overwhelmingly of biogenic origin. Groundwater-quality monitoring around PNR found no evidence of HF-induced impacts. Two approaches for modelling induced seismicity and associated seismic risk were developed using observations of seismicity and operational parameters from PNR in 2018 and 2019. Novel methodologies developed for monitoring include use of machine learning to identify fugitive atmospheric methane, Bayesian statistics to assess changes to groundwater quality, a seismicity forecasting model seeded by the HF-fluid injection rate and high-resolution monitoring of soil-gas methane.
The project developed a risk-assessment framework, aligned with ISO 31000 risk-management principles, to assess the theoretical combined and cumulative environmental risks from operations over time. This demonstrated the spatial and temporal evolution of risk profiles: seismic and atmospheric impacts from the shale-gas operations are modelled to be localised and short-lived, while risk to groundwater quality is longer-term.
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•Risks (air, water and seismic) from exploration for shale gas in UK were explored.•Establishing baseline is critical to understanding potential environmental impacts.•Impacts were observed for atmospheric gases, seismic response, not for groundwater.•A combined risk-assessment framework was developed to model evolution of risks.•Atmospheric and seismic risk is local and short-lived; groundwater is longer-term.
Many institutions have substantial landholdings, but few consider soil carbon preservation and augmentation in their carbon management plans. A methodical framework was developed to analyse ...terrestrial carbon stocks (soil and tree biomass) for credible carbon offsetting strategies in institutional land. This approach was demonstrated at two farms (805 hectares) managed by Newcastle University. Soil carbon for three depths (0–30 cm, 30–60 cm and 60–90 cm) and above‐ground tree biomass were quantified. These data provided a terrestrial carbon baseline to evaluate future land management options and effects. Historical land‐use records enabled the following comparisons: (1) agricultural land vs. woodland; (2) arable land vs. permanent grassland; (3) organic vs. conventional farming; (4) coniferous vs. broadleaved woodland; and (5) recent vs. long‐established woodland. Carbon storage (kg/m2) varied with land usage and woodland type and age, but only agricultural land vs. woodland, and for agriculture, arable land vs. permanent grassland, significantly affected the 0–90 cm soil carbon. At the university‐managed farms, current terrestrial carbon stocks were 103,620 tonnes in total (98,050 tonnes from the 0–90 cm soil and 5,569 tonnes from tree biomass). These terrestrial carbon stocks were equivalent to sixteen years of the current carbon emissions of Newcastle University (6,406 tonnes CO2 equivalents‐C per year). Using strategies for alternative land management, Newcastle University could over 40 years offset up to 3,221 tonnes of carbon per year, or 50% of its carbon emissions at the current rate. The methodological framework developed in this study will enable institutions having large landholdings to rationally consider their estates in future soil carbon management schemes.
The thermal conductivity of soil is among the most critical parameters required to design ground heat exchangers, which are widely used as a renewable technology for providing heating and cooling for ...buildings. This paper describes the development of new test apparatus that can be used for soil specimens obtained from routine site investigation as well as reconstituted specimens. The design of the apparatus is based on the application of Fourier’s law where one directional uniform heat flux is generated through two identical specimens, producing a measurable temperature gradient that is used to calculate the thermal conductivity of the specimen. A new concept of minimizing the radial heat losses using a thermal jacket as a heat insulation barrier was examined. It was found that the no-radial heat losses condition can be achieved with thermal jacket temperature approximately equal to the average value of the ambient temperature and average specimen temperature. All parameters that can affect the measurements have been tested and the results showed a good performance with margin of error upto 5%. An application of the new test procedures involved conducting several experimental tests on undisturbed and reconstituted soil samples highlighted the simplicity of this apparatus in measuring thermal conductivity of soil under different conditions.
In urban areas, pre‐existing concrete‐based demolition wastes and purposely introduced crushed dolerite have been used to create artificial soils, which capture carbon (C) as carbonate minerals and ...offset greenhouse gas (GHG) emissions. Arbuscular mycorrhizal fungi (AMF) can enhance capture of C in artificial soils through production of glomalin‐related soil protein (GRSP), which facilitates soil organic carbon (SOC) storage and aggregation, and may also enhance precipitation of soil inorganic carbon (SIC). In this paper, we show how different mixtures of dolerite and concrete affect AMF community structure and function, GRSP fractions, and soil organic and inorganic carbon contents. We used nine demonstration plots, 1 m deep, to simulate a constructed urban soil, consisting of different proportions (0, 30, 50, 70 and 100%) of either crushed concrete demolition waste or dolerite quarry fines and sown to a species‐rich meadow mixture, to investigate AMF colonization and community structure (using DNA terminal restriction fragment length polymorphism), contents of easily‐extractable and difficultly‐extractable GRSP, and both organic and inorganic carbon contents. All artificial soils supported functioning AMF communities with different levels of GRSP, SIC and SOC. The 100% dolerite and 100% concrete soils had higher values of difficultly‐to‐extract GRSP andSOC than pure sand, whereas 100% concrete had higher AMF colonization and SOC than sand. AMF community analysis indicated that high GRSP producing species were abundant in 100% dolerite and 100% concrete. These findings demonstrate that there is potential to incorporate demolition waste or dolerite products into the land to support environmental sustainability and enhance soil C sequestration.
Highlights
In constructed soils, crushed concrete and dolerite more effectively enhance GRSP and soil organic and inorganic carbon contents than sand.
Use of crushed concrete and dolerite in plant‐growing substrates is a novel way to combat climate change.
This review compiles, summarizes and provides new analytical insights on large amounts of fragmented information on the diets and feeding behaviours of syngnathids (Family Syngnathidae). This review ...is broken down into two distinct sections that address two central questions: (1) How, where, when and what do syngnathids eat? And (2) How does diet differ with feeding morphology? For (1) we summarized both qualitative and quantitative information on the diets and feeding behaviours of syngnathids found in the published and grey literature. This section includes a narrative summary of syngnathid feeding events and foraging behaviours (e.g. body mechanics and feeding morphologies, habitat use, seasonal and diurnal timing of feeding, energetics) and a tabulated summary of what syngnathids eat. For (2) we performed a comparative analysis on the diets of 41 species of syngnathid, comprising 15 genera from 39 sources in peer-reviewed and grey literature. Redundancy analyses on bulk, numeric, and frequency of occurrence data, analyzed separately, all show large unexplained dietary variation, which we hypothesize is the result of large differences in prey availability. Of the explained variation, syngnathid diets were most strongly correlated with head characteristics: most notably relative snout lengths and gape sizes. Syngnathid feeding morphologies also showed high phylogenetic signal; this suggests that dietary differences across genera were largely explained by how syngnathids differed with respect to these feeding morphologies. This review identifies new taxonomic patterns, and expands on previous generalities, improving our ecological understanding of this diverse group of fishes.
The magnesium isotopic composition of Earth is not yet well constrained despite significant advances in methods for measuring Mg isotope ratios in rocks. One impediment to establishing
25Mg/
24Mg and
...26Mg/
24Mg of Earth is the lack of constraints on inter-mineral Mg isotope fractionations at high temperatures. Advances in computational chemistry afford the capacity to predict quantitatively Mg isotope fractionations among high-temperature minerals. High-precision MC-ICPMS measurements in turn provide the opportunity to test these predictions in well-characterized samples. Toward this end, we present new high-precision
25Mg/
24Mg and
26Mg/
24Mg measurements of mantle minerals and compare these ratios with predictions for temperature-dependent inter-mineral fractionations. Our results for two San Carlos volcanic field xenoliths show that there is measurable and systematic fractionation in Mg isotope ratios between constituent minerals that are consistent with theoretical predictions. The observed order from highest to lowest
25Mg/
24Mg is spinel
>
clinopyroxene
>
orthopyroxene
>
olivine. The fractionation between spinel and olivine suggests an equilibration temperature of 814°
+/−
60
°C based on the temperature dependence obtained from ab initio calculations. This temperature is consistent with independent
T indicators involving spinel, suggesting that spinel and olivine are in Mg isotopic equilibrium in these mantle rocks, and lending credence to the accuracy of the results. Pyroxene, on the other hand, is apparently not in Mg isotopic equilibrium with spinel and olivine if the predicted temperature-dependent fractionations are correct. Consideration of the influences of modal abundances and inter-mineral fractionations on the Mg isotopic compositions of mantle minerals, and comparisons to new meteorite data reported herein, strengthen previous suggestions that the Earth may be different from carbonaceous chondrites in
25Mg/
24Mg.
When glaciers retreat they expose barren substrates that become colonized by organisms, beginning the process of primary succession. Recent studies reveal that heterotrophic microbial communities ...occur in newly exposed glacial substrates before autotrophic succession begins. This raises questions about how heterotrophic microbial communities function in the absence of carbon inputs from autotrophs. We measured patterns of soil organic matter development and changes in microbial community composition and carbon use along a 150-year chronosequence of a retreating glacier in the Austrian Alps. We found that soil microbial communities of recently deglaciated terrain differed markedly from those of later successional stages, being of lower biomass and higher abundance of bacteria relative to fungi. Moreover, we found that these initial microbial communities used ancient and recalcitrant carbon as an energy source, along with modern carbon. Only after more than 50 years of organic matter accumulation did the soil microbial community change to one supported primarily by modern carbon, most likely from recent plant production. Our findings suggest the existence of an initial stage of heterotrophic microbial community development that precedes autotrophic community assembly and is sustained, in part, by ancient carbon.
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