Barbara Maher

Lancaster University | LU · Lancaster Environment Centre

In well-buffered modern soils, higher annual rainfall is associated with enhanced soil ferrimagnetic mineral content, especially of ultrafine particles that result in distinctive observable rock magnetic properties. Hence, paleosol magnetism has been widely used as a paleoprecipitation proxy. Identifying the dominant mechanism(s) of magnetic enhanc...

Road-deposited dust (RD) is a pervasive form of particulate pollution identified (typically via epidemiological or mathematical modelling) as hazardous to human health. Finer RD particle sizes, the most abundant (by number, not mass), may pose greater risk as they can access all major organs. Here, the first in vitro exposure of human lung epitheli...

Exposure to traffic-related particulate air pollution has been linked with excess risks for a range of cardiovascular, respiratory and neurological health outcomes; risks likely to be exacerbated in young children attending schools adjacent to highly-trafficked roads. One immediate way of reducing airborne PM concentrations at the local (i.e., near...

Iron-bearing particulate matter produced by vehicle emissions is known to be toxic. To better quantify potential health risks, we have conducted the first magnetic study of a time-series of London's inhalable particulate matter (<10 μm, PM10), captured by three monitoring stations in central London (Marylebone Road, Earl's Court Road and Oxford Str...

We report the characterization of anthropogenic magnetic particulate matter (MPM) collected on leaves from roadside Callistemon (bottlebrush) trees from Lahore, Pakistan, and on known sources of traffic-related particulates to assess the potential of first-order reversal curve (FORC) diagrams to discriminate between different sources of anthropogen...

Exposure to particulate air pollution has been associated with a variety of respiratory, cardiovascular and neurological problems, resulting in increased morbidity and mortality worldwide. Brake-wear emissions are one of the major sources of metal-rich airborne particulate pollution in roadside environments. Of potentially bioreactive metals, Fe (e...

The presence of magnetic nanoparticles (MNPs) in the human brain was attributed until recently to endogenous formation; associated with a putative navigational sense, or with pathological mishandling of brain iron within senile plaques. Conversely, an exogenous, high-temperature source of brain MNPs has been newly identified, based on their variabl...

Fewer than 5% of Alzheimer’s disease (AD) cases are demonstrably directly inherited, indicating that environmental factors may be important in initiating and/or promoting the disease. Excess iron is toxic to cells; iron overload in the AD brain may aggressively accelerate AD. Magnetite nanoparticles, capable of catalyzing formation of reactive oxyg...

Magnetic signals in deep‐sea sediments have the potential to unravel past continental environmental changes, via changes in primary terrigenous magnetic supply, but also record past marine environmental conditions, via in situ formation of secondary magnetic minerals, particularly when complemented by independent proxies. By combining environmagnet...

Inhaled particulate matter (PM) from combustion- and friction-sourced air pollution adversely affects organs distant from the lung. A putative mechanism for the remote effect of inhaled PM is that ultrafine, nano-sized fraction (<100 nm) translocates across the air-tissue barrier, directly interacting with phagocytic tissue cells. Although PM is re...

Here, we use magnetic methods first to quantify the content of strongly magnetic particles of banknotes (US dollars, USD, and British pounds sterling, GBP), and then examine the possibility of their release from handled banknote surfaces. The content of magnetic particles, from magnetic remanence measurements, for the USD and paper GBP banknotes is...

Exposure to indoor air pollution is known to affect respiratory and cardiovascular health, but little is known about its effects on cognitive function. We measured the concentrations and magnetite content of airborne particulate matter (PM) in the indoor environment arising from burning peat, wood or coal in residential open fires. Highest indoor P...

Fine particulate air pollution (PM2.5) exposures are linked with Alzheimer’s and Parkinson’s diseases. AD and PD neuropathological hallmarks are documented in children and young adults exposed lifelong to Metropolitan Mexico City air pollution; together with high frontal metal concentrations (especially iron)–rich nanoparticles (NP), matching air p...

Exposure to airborne particulate matter (PM) is associated with pulmonary, cardiovascular and neurological problems. Magnetite, a mixed Fe²⁺/Fe³⁺ oxide, is ubiquitous and abundant in PM in urban environments, and might play a specific role in both neurodegeneration and cardiovascular disease. We collected samples of vehicle exhaust emissions, and o...

Exposure to particulate air pollution is a major environmental risk factor for cardiovascular mortality and morbidity, on a global scale. Both acute and chronic cardiovascular impacts have so far been attributed to particulate-mediated oxidative stress in the lung and/or via ‘secondary’ pathways, including endothelial dysfunction, and inflammation....

Exposure to air pollutants is associated with an increased risk of developing Alzheimer's disease (AD). AD pathological hallmarks and cognitive deficits are documented in children and young adults in polluted cities (e.g. Metropolitan Mexico City, MMC). Iron-rich combustion- and friction-derived nanoparticles (CFDNPs) that are abundantly present in...

Air pollution is a risk factor for cardiovascular and Alzheimer's disease (AD). Iron-rich, strongly magnetic, combustion- and friction-derived nanoparticles (CFDNPs) are abundant in particulate air pollution. Metropolitan Mexico City (MMC) young residents have abundant brain CFDNPs associated with AD pathology. We aimed to identify if magnetic CFDN...

Fewer than 5% of Alzheimer’s disease (AD) cases are demonstrably directly inherited, indicating that environmental factors may be important in initiating and/or promoting the disease. Excess iron is toxic to cells; iron overload in the AD brain may aggressively accelerate AD. Magnetite nanoparticles, capable of catalysing formation of reactive oxyg...

Air pollution is a risk factor for cardiovascular and Alzheimer's disease (AD). Iron-rich, strongly magnetic, combustion- and friction-derived nanoparticles (CFDNPs) are abundant in particulate air pollution. Metropolitan Mexico City (MMC) young residents have abundant brain CFDNPs associated with AD pathology. We aimed to identify if magnetic CFDN...

Human exposure to airborne ultrafine (<<1 µm) particulate pollution may pose substantial hazard to human health, particularly in urban roadside environments where very large numbers of people are frequently exposed to vehicle-derived ultrafine particles (UFPs). For mitigation purposes, it is timely and important to quantify the deposition of traffi...

Significance In the famous Chinese Loess Plateau (CLP), weakly magnetic, windblown dust layers alternate with variably magnetic fossil soils, recording monsoonal variations through the last ∼3 My. The soils contain strongly magnetic iron oxides, formed in situ, the mineralogy and paleoclimatic significance of which are controversial. Reduction of i...

The evolution of the Yangtze River, and specifically how and when it connected to the East China Sea, has been hotly debated with regard to possible linkages with the so-called ‘Cenozoic Topographic Reversal’ (tectonic tilting of continental east China in the Cenozoic) and particularly the relationship to the uplift history of the Tibetan Plateau....

Biomagnetic monitoring of atmospheric pollution is a growing application in the field of environmental magnetism. Particulate matter (PM) in atmospheric pollution contains readily-measurable concentrations of magnetic minerals. Biological surfaces, exposed to atmospheric pollution, accumulate magnetic particles over time, providing a record of loca...

SI1: Theoretical background on different magnetic minerals, their responses to an induced magnetic field, magnetic units, domain states and grain sizes. SI2: Inventory table of reported magnetic studies on pumped-air filters and biological sensors.

Whether during past climate stages or into a progressively warming world, changes in precipitation constitute a key component of climatic change. Quantitative proxies for palaeo-precipitation are relatively rare. The magnetic properties of the windblown loess units and interbedded palaeosols of the famous Chinese Loess Plateau provide key palaeo-pr...

Significance We identify the abundant presence in the human brain of magnetite nanoparticles that match precisely the high-temperature magnetite nanospheres, formed by combustion and/or friction-derived heating, which are prolific in urban, airborne particulate matter (PM). Because many of the airborne magnetite pollution particles are <200 nm in d...

Holocene environmental changes are interpreted in four long marine sediment cores from the Zrmanja river mouth, Novigradsko more, Karinsko more and Modrić bay, and fourteen soil sediment cores or profiles in their respective catchments. Marine sediments span throughout the whole Holocene sequence.

Airborne particulate matter (PM) has become a serious problem, and urban plants can play important roles in reducing PM concentrations in the air. The morphology, size, and elemental composition of PM on tree leaves (five evergreen species) from Beijing, China, were obtained, together with number density of PM size fraction, by using scanning elect...

The magnetic properties of well-drained, near-neutral modern soils exhibit strong relationships with mean annual precipitation (MAP, conventional 30-year averages). The pedogenic magnetic susceptibility is low for low map values (≈ 300 mm/yr), increases with increasing map (up to ≈ 1500 mm/yr), and then flattens or declines for higher map values. T...

Exposure to airborne particulate pollution is associated with premature mortality and a range of inflammatory illnesses, linked to toxic components within the particulate matter (PM) assemblage. The effectiveness of trees in reducing urban PM10 concentrations is intensely debated. Modelling studies indicate PM10 reductions from as little as 1% to a...

Determining sources, quantities and travel distances of eroding soil is of increasing importance given its impact on‐ and off‐site, the sediment‐associated transport of nutrients, metals and micro‐organisms and the ongoing need to provide data for soil erosion model development and validation. Many soil tracers have been developed; however, most co...

Oxygen isotope variations in Chinese stalagmites have been widely interpreted as a record of the amount of East Asian summer monsoonal rainfall. This interpretation infers decreasing monsoonal rainfall from the mid-Holocene and large, dipolar rainfall oscillations within glaciations. However, the speleothem δ18O variations conflict with independent...

Emissions of particulate matter (PM) from vehicle and industrial sources constitute a hazard to human health. Here, we apply biomagnetic monitoring to (a) discriminate between potential PM(10) sources around a steelworks and (b) examine magnetic source differentiation for a combined, U.K.-based, magnetic data set (steelworks, roadside, power-genera...

Changes in the sources, properties and fluxes of mineral aerosol (‘dust’) have significance as both indicators and agents of climate change, through radiative, cloud condensation and ocean biogeochemical effects. Quaternary aeolian sediments, worldwide in distribution, can comprise high-resolution archives of past climatic and environmental change,...

In recent studies, the saturation isothermal remanent magnetization (SIRM) of leaves has been used for monitoring of atmospheric particulate matter. This study examined leaf SIRM of tree species with different leaf surface characteristics in the urban environment of Gent (Belgium). Leaf SIRM was measured from co-located trees of Carpinus betulus (w...

Flake based assemblages (Mode 1) comprise the earliest stone technologies known, with well-dated Oldowan sites occurring in eastern Africa between ∼ 2.6-1.7 Ma, and in less securely dated contexts in central, southern and northern Africa. Our understanding of the spread and local development of this technology outside East Africa remains hampered b...

The sedimentary succession of the West Runton Freshwater Bed (WRFB) is described and interpreted. The sediments represent a fluvial valley floor accumulation that trends west- to east, subparallel to the modern cliffline. Stabilisation of the stream channels was initially followed by deposition of fine-grained silt in standing water, punctuated by...

We present the results of magnetic measurements (low field susceptibility, anhysteretic and isothermal remanences) on samples of sediment from 11 cores from the Potomac River between Washington DC and its mouth. The magnetic properties indicate that at sites in the upstream reaches especially, there has been a shift to surface-soil-derived sediment...

The dispersal of early humans from Africa by 1.75 Myr ago led to a marked expansion of their range, from the island of Flores in the east to the Iberian peninsula in the west. This range encompassed tropical forest, savannah and Mediterranean habitats, but has hitherto not been demonstrated beyond 45 degrees N. Until recently, early colonization in...

Evaluation of health impacts arising from inhalation of pollutant particles <10 microm (PM(10)) is an active research area. However, lack of exposure data at high spatial resolution impedes identification of causal associations between exposure and illness. Biomagnetic monitoring of PM(10) deposited on tree leaves may provide a means of obtaining e...

Biomagnetic monitoring, using tree leaves as passive surfaces for particle collection, has been shown to be a promising technique for assessing the dispersion and deposition of particles in the context of anthropogenic pollution. By comparing leaves' magnetic properties with trace metal levels measured in the leaves, we here assess the utility of t...

Reliable dating of glaciomarine sediments deposited on the Antarctic shelf since the Last Glacial Maximum (LGM) is challenging because of the rarity of calcareous (micro-) fossils and the recycling of fossil organic matter. Consequently, radiocarbon (14C) ages of the acid-insoluble organic fraction (AIO) of the sediments bear uncertainties that are...

Palaeo-dust records in sediments and ice cores show that wind-borne mineral aerosol ('dust') is strongly linked with climate state. During glacial climate stages, for example, the world was much dustier, with dust fluxes two to five times greater than in interglacial stages. However, the influence of dust on climate remains a poorly quantified and...

For the terrestrial environment, sequences of loess sediments provide key aeolian archives on every continent. High-resolution loess/palaeosol sequences can provide both quantitative information on the soil-forming palaeoclimate, and mineralogical, physical and chemical information on dust and dust fluxes. The sensitivity of iron minerals in these...

Mineral dust is an active climate system component that may significantly influence the radiative balance of the atmosphere as well as biogeochemical cycles. However, the complex linkages between dust-generating processes and past or anthropogenic climate change are still poorly constrained. The highly successful Dust Indicators and Records of Terr...

The timing of the grounding-line retreat of marine-based ice sheets from the Antarctic shelf after the last glacial maximum (LGM) is not well constrained. Most of the published deglaciation ages are AMS 14C dates obtained from the acid-insoluble fraction of the bulk organic matter (AIO) or from calcareous (micro-)fossils in biogenic glaciomarine se...

The last decades has seen the increasing development of new technologies for tracing the movement of sediment across landscapes, including rare earth element oxides, fluorescent particles and DNA tags. These new tracers allow us to tag soil particles using a chemical marker or introduce particles to the soil that mimic its behaviour. Once applied t...

Reliable dating of glaciomarine sediments deposited on the Antarctic shelf since the Last Glacial Maximum (LGM) is very challenging because of the general absence of calcareous (micro-) fossils and the recycling of fossil organic matter. As a consequence, radiocarbon (14C) ages of the acid-insoluble organic fraction (AIO) of the sediments bear unce...

Two contrasting examples of the application of mineral magnetism to environmental problems are discussed. Magnetic susceptibility measurements of sediments from the Chinese Loess Plateau - the biggest accumulation of windblown sediments on Earth - reveal one of the best records of continental climate change available. These records provide a detail...

Accelerated erosion of fine-grained sediment is an environmental problem of international dimensions. Erosion control strategies and targeting of mitigation measures require robust and quantitative identification of sediment sources. Here, we use magnetic ‘fingerprinting’ to characterize soils, and examine their affinity with and contribution to su...

Accelerated erosion and transport of fine sediment from upland temperate catchments can reflect increased erosivity and/or erodibility, due in turn to climatic and/or human forcing. Identification of sediment fluxes and sources over Holocene timescales can both enable understanding of the relative impacts of these forcings and provide perspective o...

Inhalation of particulate pollutants below 10 μm in size (PM10) is associated with adverse health effects. Here we use magnetic remanence measurements of roadside tree leaves to examine levels of vehicle-derived PM around Lancaster, UK. Leaf saturation remanence (SIRM) values exhibit strong correlation with both the SIRM and particulate mass of co-...

The sources and fluxes of sediment to the Great Barrier Reef lagoon from north-eastern Australian rivers have been the subject of much concern and study, with the large catchments of the Burdekin and Fitzroy Rivers thought to be the key sources at present. Here, the utility of newly developed magnetic ‘fingerprinting’ methods for identifying sedime...

Since 1951, the character of Greece has changed from a mainly agricultural into a more industrial country. In the course of the economic revival, this change implied a rapid development of urban and industrial areas, resulting in serious consequences for the Hellenic environment. The present study focuses on fly ash and heavy metal pollution, one o...

Controversy exists regarding the sources of the eolian dust for the immense Loess Plateau of north-central China, the largest accumulation of windblown loess in the world. Because the loess accumulation rate, unit thickness, and particle size all decrease from northwest to southeast, it has long been thought that the northern deserts, especially th...

Robust identification of catchment suspended sediment sources is a prerequisite both for understanding sediment delivery processes and targeting of effective mitigation measures. Fine sediment delivery can pose management problems, especially with regard to nutrient run-off and siltation of water courses and bodies. Suspended sediment load constitu...

Mineral aerosol (referred to here as “dust”) is an active climate and paleoclimate system component that may significantly influence the radiative properties of the atmosphere, as well as ocean and atmospheric carbon dioxide (CO2) concentrations, through processes such as iron fertilization. The integrative, cross-cutting examination of the role an...

The loess and palaeosols of the famous Chinese Loess Plateau span more than the last 2 million years of Earth's history, preserving the longest, most detailed record of Quaternary climatic changes yet found on land. More loess/palaeosol sequences occur in both hemispheres, also acting as potential climate archives albeit for shorter time spans. Giv...

The Southern Ocean is a high nutrient, low chlorophyll (HNLC) region of the world oceans; productivity and subsequent drawdown of carbon dioxide from the atmosphere can be enhanced with increases in bioavailable iron supply. The past record of terrestrial dust flux to the Southern Ocean thus carries potential significance with regard to whether thi...

In a preliminary study, paired indoor and outdoor air sampling was conducted at three locations around the city of Lancaster, UK to examine the influence of combustion sources on air quality by measuring particulate concentrations, particulate magnetic properties and polyaromatic hydrocarbons (PAHs). With one exception (an indoor suburban air sampl...

We examine sediment dynamics in an upland, temperate lake system, Lake Bassenthwaite (NW England), in the context of changing climate and land use, using magnetic and physical core properties. Dating and analysis of the sedimentary records of nine recovered cores identify spatially variable sedimentation rates across the deep lake basin. Mineral ma...

Oxygen isotope records from stalagmites in caves in southern China, interpreted as proxy rainfall records reflecting the intensity of the East Asian summer monsoon, indicate gradual monsoon weakening for the last ~9000 years, as also documented for the Indian monsoon. Coupled with high-precision dating, the speleothem proxy records have been used t...

Atmospheric dust both absorbs and scatters solar radiation (the direct radiative effect, RE), which alters the energy balance of the atmosphere. In addition, dust plays an important role in cloud microphysics, and impacts the formation and lifetime of clouds (the indirect RE), which influences the planetary albedo. According to the IPCC Fourth Asse...

Robust identification of catchment suspended sediment sources is a prerequisite both for understanding sediment delivery processes and targeting of effective mitigation measures. Fine sediment delivery can pose universal management problems, especially with regard to nutrient run-off and lake siltation. Here, 19 suspended sediment samplers were loc...

Exposure to metal-rich particulate pollution is associated with adverse health outcomes. In particular, lead has recently been shown to be toxic in young children even at low levels previously considered ‘safe’. Lead poisoning from vehicle pollution has been addressed internationally by removal of leaded petrol but toxic blood lead levels in childr...

The influence of dust on climate, through changes in the radiative properties of the atmosphere and/or the CO2 content of the oceans and atmosphere (through iron fertilisation of high nutrient, low chlorophyll, HNLC, regions of the world's oceans), remains a poorly quantified and actively changing element of the Earth's climate system. Dust-cycle m...

Artificial iron fertilization experiments in the Southern Ocean - a high nutrient, low chlorophyll (HNLC) region of the world oceans - indicate that productivity and subsequent drawdown of carbon dioxide from the atmosphere can be enhanced with increases in bioavailable iron supply. The past record of terrestrial dust flux to the Southern Ocean thu...