Late-Holocene land surface change in a coupled social-ecological system, southern Iceland : a cross-scale tephrochronology approach

This work is supported by a UK Natural Environment Research Council (NERC) PhD studentship (NE/F00799X/1)The chronological challenge of cross-scale analysis within coupled socio-ecological systems can be met with tephrochronology based on numerous well-dated tephra layers. We illustrate this with an enhanced chronology from Skaftártunga, south Iceland that is based on 200 stratigraphic profiles and 2635 individual tephra deposits from 23 different eruptions within the last 1140 years. We present new sediment-accumulation rate based dating of tephra layers from Grímsvötn in AD 1432 ± 5 and AD 1457 ± 5. These and other tephras underpin an analysis of land surface stability across multiple scales. The aggregate regional sediment accumulation records suggest a relatively slow rate of land surface change which can be explained by climate and land use change over the period of human occupation of the island (after AD ∼870), but the spatial patterning of change shows that it is more complex, with landscape scale hysteresis and path dependency making the relationship between climate and land surface instability contingent. An alternative steady state of much higher rates of sediment accumulation is seen in areas below 300 m asl after AD ∼870 despite large variations in climate, with two phases of increased erosion, one related to vegetation change (AD 870–1206) and another related to climate (AD 1597–1918). In areas above 300 m asl there is a short lived increase in erosion and related deposition after settlement (AD ∼870–935) and then relatively little additional change to present. Spatial correlation between rates of sediment accumulation at different profiles decreases rapidly after AD ∼935 from ∼4 km to less than 250 m as the landscape becomes more heterogeneous. These new insights are only possible using high-resolution tephrochronology applied spatially across a landscape, an approach that can be applied to the large areas of the Earth's surface affected by the repeated fallout of cm-scale tephra layers.PostprintPeer reviewe

Catalytic performance of carbonaceous materials in the esterification of succinic acid

Mesoporous carbonaceous materials have outstanding potential in many different applications such as adsorption, medicine and catalysis. We have recently reported the synthesis of a new form of mesoporous carbon, named Starbon((R)), obtained after low temperature carbonization of expanded starch. Such starch-derived mesoporous materials have several tunable properties including surface energies (ranging from hydrophilic to hydrophobic surfaces), which can be easily controlled by the degree of carbonization (from 200 to 700 degrees C). Due to the diversity of surface functional groups, Starbons((R)) can be easily chemically modified. Treatment of Starbon((R)) materials with sulfuric acid gave a solid acid that has promising properties as heterogeneous catalyst. Comparative catalytic studies with some other similar commercial carbonaceous materials such as DARCO((R)) and NORIT (R), as well as phosphorous-containing microporous carbons, are reported. (c) 2008 Elsevier B.V. All rights reserved

Superior Mesoporosity of Lipid Free Spent Coffee Grounds Residues

As part of the biorefinery concept for spent coffee grounds (SCG), production of activated carbon (AC) was investigated from the degreased coffee grounds (DCG) left behind after oil extraction (primarily for biodiesel). The oils were extracted via conventional solvent extraction with GC/GC-MS confirming the oil was comparable to oils produced industrially. More significantly, analysis showed the DCG AC to have a 4-fold increase in mesoporosity than the SCG AC with mesopore volumes of 0.6 and 0.15 cm3 g-1 respectively. Adsorption trials showed a ten-fold increase in capacity for Au(III) from 8.7 to 88.6 mg/g with subsequent experiments confirming that DCG AC displayed standard behavior for mesoporous materials of increasing adsorption capacity with decreasing pH. This raises the potential for valorization of SCG into a functional material for water remediation without the need for templating agents or expansion pre-treatments with the added bonus of an additional material being produced simultaneously

Production of Hydrogels from Microwave-Assisted Hydrothermal Fractionation of Blackcurrant Pomace

The exploitation of unavoidable food supply chain wastes resulting from primary and secondary processing for chemicals, materials, and bioenergy is an important concept in the drive towards circular-based, resource-efficient biorefineries rather than petroleum refineries. The potential production of hydrogels (materials) from unavoidable food supply chain wastes, which are naturally rich in biopolymers such as cellulose, hemicellulose, pectin, and lignin, represents an interesting opportunity. However, these intertwined and interconnected biopolymers require separation and deconstruction prior to any useful application. Thus, this study aims to explore the formation of hydrogels from defibrillated celluloses (MW-DFCs) produced via acid-free stepwise microwave hydrothermal processing of blackcurrant pomace residues. Initially, pectin was removed from blackcurrant pomace residues (MW, 100–160 ◦C), and the resultant depectinated residues were reprocessed at 160 ◦C. The pectin yield increased from 2.36 wt.% (MW, 100 ◦C) to 3.07 wt.% (MW, 140 ◦C) and then decreased to 2.05 wt.% (MW, 160 ◦C). The isolated pectins were characterized by attenuated total reflectance infrared spectroscopy (ATR-IR), thermogravimetric analysis (TGA), and 13C NMR (D2O). The cellulosic-rich residues were reprocessed (MW, 160 ◦C) and further characterized by ATR-IR, TGA, and Klason lignin analysis. All the MW-DFCs contained significant lignin content, which prevented hydrogel formation. However, subsequent bleaching (H2O2/OH−) afforded off-white samples with improved gelling ability at the concentration of 5% w/v. Confocal laser microscopy (CLSM) revealed the removal of lignin and a more pronounced cellulosic-rich material. In conclusion, the microwave-assisted defibrillation of blackcurrant pomace, an exploitable unavoidable food supply chain waste, affords cellulosic-rich materials with the propensity to form hydrogels which may serve useful applications when put back into food products, pharmaceuticals, cosmetics, and home and personal care products

Byproduct Valorization : From Spent Coffee Grounds to Fatty Acid Ethyl Esters

A laboratory experiment was designed to provide students with an introduction to byproduct valorization by producing an analogue of biodiesel (fatty acid ethyl esters, FAEE) via lipid extraction and subsequent transesterification from spent coffee grounds (SCG). Valorization is the process of upgrading underutilized or discarded wastes or byproducts into chemicals, materials, and (bio)energy. Upon isolation of the intermediate and FAEE, students analyzed the respective spectroscopic characteristics using infrared and nuclear magnetic resonance spectroscopy as well as evaluated gas chromatography spectra that were provided. Associated green metrics for the reaction were determined to obtain a quantitative measure of the “greenness” of the experiment. In this laboratory experiment, students are introduced to key concepts such as whole systems thinking and the United Nations Sustainable Development Goals where they apply these frameworks to real-world problems such as consumption and waste disposal. In addition to providing a greener alternative to traditional methods for biodiesel analogue production from SCG by solvent alterations, this experiment demonstrates the value of waste that would otherwise be overlooked to generate products that can help reduce the continued use of finite fossil fuels

Landscapes of Settlement in Northern Iceland: Historical Ecology of Human Impact and Climate Fluctuation on the Millennial Scale

Early settlement in the North Atlantic produced complex interactions of culture and nature. The sustained program of interdisciplinary collaboration is intended to focus on ninth- to 13th-century sites and landscapes in the highland interior lake basin of M´yvatn in Iceland and to contribute a long-term perspective to larger issues of sustainable resource use, soil erosion, and the historical ecology of global change

Continuity in the face of a slowly unfolding catastrophe : the persistence of Icelandic settlement despite large-scale soil erosion

The National Science Foundation of America provided financial support for this research through grants 1202692 ‘Comparative Island Ecodynamics in the North Atlantic’, and 1249313 ‘Tephra layers and early warning signals for critical transitions’.Soil erosion in Iceland since people first settled the island about 1,100 years ago has fundamentally changed some 15-30% of the island’s total surface area. This provides a unique case to evaluate the consequences of a slowly unfolding environmental catastrophe that has affected, and is continuing to affect a primary means of subsistence for a whole society. Buffered by the sufferings of regions of Iceland, individual farms and particular social groups, Icelandic society as a whole has endured through subsistence flexibility, social inequalities, and the ability to tap into larger provisioning and economic networks. This demonstrates how an adaptable people can confront challenges through social organisation and by diversifying their impacts ecosystems. In the medium term—multi-century timescales—this can be an effective, if costly, strategy, in terms of both the environment and society. Soil conservation is now a national priority, woodland is returning, and climate warming is opening up more potentials for Icelandic arable agriculture. However, the slow catastrophe of Icelandic soil erosion is still unfolding, with the perspective of the longue durée it is evident that decisions made in the Viking Age and medieval period still resonate, constraining future options for resilience and adaptive flexibility.Postprin

Archaeological sites as Distributed Long-term Observing Networks of the Past (DONOP)

The authors would also like to acknowledge the support of the National Science Foundation, specifically the Arctic Social Sciences Program, and RANNIS (The Icelandic Center for Research).Archaeological records provide a unique source of direct data on long-term human-environment interactions and samples of ecosystems affected by differing degrees of human impact. Distributed long-term datasets from archaeological sites provide a significant contribution to establish local, regional, and continental-scale environmental baselines and can be used to understand the implications of human decision-making and its impacts on the environment and the resources it provides for human use. Deeper temporal environmental baselines are essential for resource and environmental managers to restore biodiversity and build resilience in depleted ecosystems. Human actions are likely to have impacts that reorganize ecosystem structures by reducing diversity through processes such as niche construction. This makes data from archaeological sites key assets for the management of contemporary and future climate change scenarios because they combine information about human behavior, environmental baselines, and biological systems. Sites of this kind collectively form Distributed Long-term Observing Networks of the Past (DONOP), allowing human behavior and environmental impacts to be assessed over space and time. Behavioral perspectives are gained from direct evidence of human actions in response to environmental opportunities and change. Baseline perspectives are gained from data on species, landforms, and ecology over timescales that long predate our typically recent datasets that only record systems already disturbed by people. And biological perspectives can provide essential data for modern managers wanting to understand and utilize past diversity (i.e., trophic and/or genetic) as a way of revealing, and potentially correcting, weaknesses in our contemporary wild and domestic animal populations.PostprintPeer reviewe

Ginger waste as a potential feedstock for a zero-waste ginger biorefinery : A review

Ginger for consumption and use in industrial applications such as essential oil and oleoresin extraction is growing globally. There will be increased volumes of ginger waste (rhizomes, stems and leaves) in the coming years. However, the valorisation of ginger waste is limited in the literature beyond its use as a ginger meal for animal feed. Herein, this review consolidates the literature on ginger waste within the context of developing a zero-waste ginger biorefinery that yields chemicals, materials and (bio)energy for emerging bio-based markets and applications. Green extraction technologies are reported, some are at an industrial scale for processing fresh ginger but which could be re-used to obtain a second crop of oil or oleoresin. The application of ginger waste to produce potential value-added products such as anti-microbial materials, environmental remediation agents, supercapacitors, bioenergy and heterogeneous catalysts is presented. Limitations based on logistics, feedstock, processing technology and final output are discussed

Climate challenges, vulnerabilities, and food security

This paper identifies rare climate challenges in the long-term history of seven areas, three in the subpolar North Atlantic Islands and four in the arid-to-semiarid deserts of the US Southwest. For each case, the vulnerability to food shortage before the climate challenge is quantified based on eight variables encompassing both environmental and social domains. These data are used to evaluate the relationship between the “weight” of vulnerability before a climate challenge and the nature of social change and food security following a challenge. The outcome of this work is directly applicable to debates about disaster management policy