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This Perspective discusses the prospective strategies for overcoming the stability and capacity trade-off associated with increased Ni content in layered Ni-rich Li[NixCoyMnz]O2 (NCM) and Li[NixCoy...

To understand the effect of selenium doping on the good cycling performance and rate capability of a Ge0.9Se0.1 electrode, the dynamic morphological and phase changes of the Ge0.9Se0.1 electrode were investigated by synchrotron-based operando transmission X-ray microscopy (TXM) imaging, X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The TXM results show that the Ge0.9Se0.1 particle retains its original shape after a large volume change induced by (de)lithiation and undergoes a more sudden morphological and optical density change than pure Ge. The difference between Ge0.9Se0.1 and Ge is attributed to a super-ionically conductive Li–Se–Ge network formed inside Ge0.9Se0.1 particles, which contributes to fast Li-ion pathways into the particle and nano-structuring of Ge as well as buffering the volume change of Ge. The XRD and XAS results confirm the formation of a Li–Se–Ge network and reveal that the Li–Se–Ge phase forms during the early stages of lithiation and is an inactive phase. The Li–Se–Ge network also can suppress the formation of the crystalline Li15Ge4 phase. These in situ and operando results reveal the effect of the in situ formed, super-ionically conductive, and inactive network on the cycling performance of Li-ion batteries and shed light on the design of high capacity electrode materials.

The dynamic information of lithium-ion battery active materials obtained from coin cell-based in-situ characterizations might not represent the properties of the active material itself because many other factors in the cell could have impacts on the cell performance. To address this problem, a single particle cell was developed to perform the in-situ characterization without the interference of inactive materials in the battery electrode as well as the X-ray-induced damage. In this study, the dynamic morphological and phase changes of selenium-doped germanium (Ge0.9 Se0.1 ) at the single particle level were investigated via synchrotron-based in-situ transmission X-ray microscopy. The results demonstrate the good reversibility of Ge0.9 Se0.1 at high cycling rate that helps understand its good cycling performance and rate capability. This in-situ and operando technique based on a single particle battery cell provides an approach to understanding the dynamic electrochemical processes of battery materials during charging and discharging at the particle level.

This study aims to provide a new platform for the fabrication of metal-carbon composites. Herein we show that the high density crosslinking of a polymer can be used to homogenously trap metal nanoparticles and other components. In this setting, we utilized the cross-linking of poly(maleic anhydride-at 1-octadecene) [PMAO] with ethylene glycol to trap metal nanoparticles and carbon nitride (C3N4) within the polymeric structure. During inert, high-temperature pyrolysis, the polymer acts as a soft-template and prevents agglomeration of metallic tin during the synthesis. Inspired by the work of Tang et al. the carbon nitride is employed to act as a nitrogen dopant source and textural template for the final product. Through an analysis variable experimental parameter, we have shown that this method provides an avenue for the tunable fabrication of nitrogen-rich porous composites. To demonstrate the practicality of this synthetic method, composites with a variety of different nitrogen moieties and textural compositions were electrochemically analyzed. The resulting composites were then used as a platform to demonstrate not only the tunability of the synthetic method but also an example of how much these effects drastically dictate the electrochemistry of the system. Of the samples analyzed it was shown that a urea based composite demonstrated the best electrochemistry touting high rate capability, stable cycling, and high coulombic efficiency (CE). The results of long-term performance testing reveal the excellent electrochemical properties of the U-Sn-CN composite, supplying an initial capacity of ~ 600 mAh g–1 and 82.0 % capacity retention over 400 cycles at a high current density of 1 A g–1 (1C) with an average CE of 99.8 %. Lower current density studies [500 mA g-1 (C/2)] have shown the material to have an initial capacity of ~ 640 mAh g–1 with 86.0 % capacity retention over 400 cycles. Electrochemical and post-mortem analysis of this composite material suggest the performance properties can be attributed to the unique nitrogen-doped carbon framework, which is able to buffer the large volumetric expansion of the tin due to its disordered flexible nature whilst contributing to the overall capacity of the composite from its high degree of nitrogen doping (~11.9 at %). Figure 1

In layered oxide cathodes for lithium-ion batteries, nickel provides high capacity but compromises stability. Although much progress has been made in upsetting this trade-off, the stability of Ni-rich cathodes is not yet adequate to satisfy the expectations of commercial batteries. Here, a layered Li[Ni0.89Co0.10Sb0.01]O2 cathode material, which overcomes the instabilities associated with highly Ni-rich cathodes to deliver excellent capacity retention, is reported. This cathode shows a significantly enhanced resistance to performance deterioration and microcrack propagation compared to the more conventional Li[Ni0.885Co0.10Al0.015]O2 material. Furthermore, it delivers more capacity than its counterpart despite the same nickel content. The robustness of the material arises from the ordering of the grains into a dense flower-petal arrangement, which collectively preserves the coherency of the particle. Through extensive cross-sectional imaging and chemical mapping, a correlation between microcracks and electrolyte infiltration into the particle is demonstrated. Figure 1

Germanium (Ge) is a promising candidate for high-capacity Li-ion battery anode due to its high theoretical capacity of 1384 mAh/g (for the charged Li15Ge4 phase), low operation voltage, fast bulk Li diffusion, and high electrical conductivity. However, the major challenge in the development of Ge anode is the large volume change involved in the reaction scheme, which could result in rapid loss of specific capacity. We recently reported that selenium (Se) -doped Ge (GeSe) forms an inactive phase that buffers the volumetric expansion of Ge which provides better cycling life and performance (1). However, the dynamic morphological and chemical transformations of GeSe that occur during battery cycling processes is still elusive. The traditional in-situ coin cell has rotating limitations which makes three-dimensional experiment difficult except via limited angle tomography. It also suffers from X-ray damage problems to the binder. To understand the dynamic morphological and chemical changes of GeSe, we developed a single particle battery cell for operando TXM and XANES. A micron-sized GeSe particle was attached to a pre-coated tungsten probe by ion beam carbon deposition on a Zeiss Nvision 40 FIB-SEM at the Center for Nanoscale Materials, Argonne National Laboratory. The single particle battery cell was assembled in an argon-filled glovebox. A small piece of Li metal was attached to a copper wire as the counter electrode. Both the tungsten and lithium electrodes were carefully inserted into a funnel-shaped open-ended silica capillary and stabilized via epoxy. The quartz housing was fully filled with 1 M LiPF6 EC/DEC electrolyte through a micro-syringe and sealed with torr seal epoxy. This binder free operando single particle cell eliminates discrepancies caused by particles overlapping in the in-situ coin cell during TXM and the impact of X-ray damage to the binder (2). It provides chemical and morphological information in three-dimensional space via computed nanotomography coupled with XANES. Figure 1 shows the performance of operando GeSe cell and the 2D morphological change of a GeSe particle attached to the tungsten probe at 11.113 keV. Regardless of the defect caused by the carbon deposition process, the results indicate that GeSe undergoes a different dynamic chemical transformation compared to pure Ge. The selenium-doped germanium has the ability to reinstate its original shape after cycling. This study can help to understand the mechanical stability and degradation mechanism of high capacity lithium alloy anode with additional stress-accommodating phase. K. C. Klavetter, J. Pedro de Souza, A. Heller, C. B. Mullins, High tap density microparticles of selenium-doped germanium as a high efficiency, stable cycling lithium-ion battery anode material. Journal of Materials Chemistry A 3, 5829-5834 (2015). L. Y. Lim, N. Liu, Y. Cui, M. F. Toney, Understanding Phase Transformation in Crystalline Ge Anodes for Li-Ion Batteries. Chemistry of Materials 26, 3739-3746 (2014). Figure 1

Increasingly modern society relies on the use of electrical energy for a large portion of their everyday tasks. Many of these tasks require the use of portable energy sources. Currently, lithium ion batteries (LIBsdominate the portable energy storage market.1 Almost exclusively, these LIBs utilize a graphite anode, due to graphite’s long lifetime and high capacity retention.2 This project aims to develop a cheap, high capacity alternative to graphite via a SnO2-C based anode material. Tin oxide is an effective candidate for an anode due to its low price and tin’s high abundance. Tin oxide anodes have been studied previously, motivated by its high theoretical capacity (1494 mAh/g).2 However, tin oxide is not currently used in commercial cells because of the large volumetric expansion during lithiation (up to 300%) leading to fracturing of the particle.3 In turn, the fracturing can cause the particle to electrically disconnect from the current collector and lose effectiveness. We believe these issues can be counteracted through the employment of a carbon backbone. The presence of semi-crystalline carbon could act as a flexible component to resist the expansion of the tin atoms, preventing the degradation and fracturing of the particle caused by expansion.4 Previous studies have utilized SnO2-C composites to form anodic materials with high capacities and high columbic efficiencies, but tend to display sub-par cycling lifetimes.4,5 However, these studies did not examine how the effects of doping and extent of crystallinity can influence the overall electrochemical performance. The analysis of these factors could lead to the production of a higher capacity and more economically viable alternative to graphitic anodes. The goal of this research is to develop SnO2-C anodes and investigate the storage and transport of Li within the electrodes to improve the efficiency and cost of LIBs. Due to their higher tap densities and industrial viability, micron-sized anode materials were generated for this study. Ditin citrate was chosen as a tin containing pyrolysis precursor because of its novelty and inexpensive synthesis.6 Precursors such as sucrose and citric acid were added to pyrolysis mixture to form a semi-graphitized framework around the tin-oxide particles. XRD, Raman, XPS, and SEM/EDX data suggest the uniform coating of a semi-graphitized coating around the SnO2 particles. Preliminary data suggest this process has led to the formation of a high specific capacity (750 mA/g) anode material with satisfactory cycling performance. The future pursuits of this study is to optimize the cycling performance and determine the effects of using dopants such as nitrogen and sulfur. 1. Tenan, M. S.; LaFiandra, M. E.; Ortega, S. V. The Effect of Soldier Marching, Rucksack Load, and Heart Rate on Marksmanship. Hum. Factors 2017, 59 (2), 259–267. https://doi.org/10.1177/0018720816671604 2. Thampan, T.; Shah, D.; Cook, C.; Novoa, J.; Shah, S. Development and Evaluation of Portable and Wearable Fuel Cells for Soldier Use. J. Power Sources 2014, 259, 276–281. https://doi.org/10.1016/j.jpowsour.2014.02.099 3. Zhu, X.; Zhu, Y.; Murali, S.; Stoller, M. D.; Ruoff, R. S. Reduced Graphene Oxide/Tin Oxide Composite as an Enhanced Anode Material for Lithium Ion Batteries Prepared by Homogenous Coprecipitation. J. Power Sources 2011, 196 (15), 6473–6477. https://www.sciencedirect.com/science/article/pii/S0378775311008020 4. Winter, M.; Besenhard, J. O. Electrochemical Lithiation of Tin and Tin-Based Intermetallics and Composites. Electrochim. Acta 1999, 45 (1), 31–50. https://www.sciencedirect.com/science/article/pii/S0013468699001917 5. Paek, S.-M.; Yoo, E.; Honma, I. Enhanced Cyclic Performance and Lithium Storage Capacity of SnO2/Graphene Nanoporous Electrodes with Three-Dimensionally Delaminated Flexible Structure. Nano Lett. 2009, 9 (1), 72–75. https://pubs.acs.org/doi/10.1021/nl802484w 6. Derrien, G.; Hassoun, J.; Panero, S.; Scrosati, B. Nanostructured Sn–C Composite as an Advanced Anode Material in High-Performance Lithium-Ion Batteries. Adv. Mater. 2007,19 (17), 2336–2340. https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.200700748 Figure 1

We report here the synthesis and fabrication of reduced graphene oxide (rGO)-based aerogels as free-standing lithium-ion battery (LIB) electrodes and 3D scaffolds for supporting conventional LIB active materials (e.g., LiFePO4, Li4Ti5O12, LiNixCoyMnzO2). As a 3D replacement for conventional metal-foil current collectors, we demonstrate the fabrication of compact (2 – 3 g cm-3) electrodes via slurry-infiltrating the porous aerogels with controlled active-material loading (~3 – 30 mg cm-2) and compressing the resultant composites to a desired thickness (~30 – 130 μm from a starting thickness of 3.2 mm). The controlled loading and tunable thickness provide high composite electrode densities that are of essence for consideration in a practical application. Replacement of the usual copper foil (anode) and aluminum foil (cathode) current collectors with the lightweight, integrated rGO-based aerogels drastically reduces the weight and volume occupied by the current collector, thereby increasing the energy density per unit volume and mass at the electrode level. We further demonstrate that the addition of poly (acrylic acid) (PAA) to the rGO scaffold (referred to as rGO-PAA) provides a versatile platform for exploring a diverse range of structure-function relationships that will guide our understanding of fabricating high-performance electrodes with the lightweight rGO aerogels. For example, due to the electrically-insulating nature of PAA, reducing its content is expected to lead to an increase in electrical conductivity of the aerogel; conversely, we show that the incorporation of PAA facilitates a more uniform pore structure that is expected to improve the ionic conductivity of Li+ ions in the electrolyte. We are exploring this versatility to identify requisite synthesis and processing conditions that optimize the trade-off between electrical conductivity, pore structure, and mechanical properties in the rGO-based aerogels. Overall, the straightforward synthesis of the rGO-based aerogels starting from inexpensive precursors (graphite and poly (acrylic acid)) provides a scalable fabrication procedure, and the use of commercially-available and high tap-density LIB active materials with the lightweight aerogels enables fabrication of composite electrodes with practical active-material loadings and electrode densities. This approach is unique from that of many other 3D electrodes that use hydrothermal, chemical deposition, or co-precipitation methods to fabricate low tap-density nanomaterials tethered to a 3D substrate that often result in low mass loadings or low volumetric energy densities.

Rice paddy fields in the Naboc area, near Monkayo on the island of Mindanao, Philippines, have been irrigated four times a year over the last decade using Naboc River water contaminated with mercury (Hg) by artisanal gold mining in the Diwalwal area. Silt containing up to at least 90 mg Hg/kg (d.w.) has been deposited in rice paddy fields during the 1990s and this has been repeatedly mixed into the rice root zone through ploughing. Hg in the rice paddy field soils averages 24 mg Hg/kg and generally exceeds the UK and Canadian soil quality thresholds for agricultural soils as well as the proposed Dutch Intervention value and the USEPA soil ingestion Soil Screening Level (SSL) for inorganic Hg. Much lower Hg concentrations (0.05-0.99 mg/kg) within the range expected for uncontaminated soils, characterise soils on which corn and bananas are cultivated, largely because these are not irrigated with Hg-contaminated water from the Naboc River. The estimated total weekly MeHg intake for a person living in the Naboc area related to the weekly consumption of 2.1 kg of rice grown on Hg-contaminated soils (15 microg MeHg) in conjunction with 1 kg of fish (220 microg MeHg) and 100 g of mussels (50 microg MeHg) from the Naboc River, would total 285 microg MeHg (equivalent to 4.75 microg/kg bw for a 60 kg adult), which is nearly three times the JECFA PTWI of 1.6 microg/kg bw. This will significantly contribute to the population mercury exposure and might explain why 38% of the local inhabitants were classified as Hg intoxicated during a mercury toxicity assessment [Drasch GS, Böse, O'Reilly S, Beinhoff C, Roider G, Maydl S. The Mt. Diwata study on the Philippines 1999-assessing mercury intoxication of the population by small scale gold mining. Sci Total Environ 2001; 267(1-3): 151-168.].

Potential contamination at ex-industrial sites means that, prior to change of use, it will be necessary to quantify the extent of risks to potential receptors. To assess ecological hazards, it is often suggested to use biological assessment to augment chemical analyses. Here we investigate the potential of a commonly recommended bioassay, the earthworm reproduction test, to assess the status of urban contaminated soils. Sample points at all study sites had contaminant concentrations above the Dutch soil criteria Target Values. In some cases, the relevant Intervention Values were exceeded. Earthworm survival at most points was high, but reproduction differed significantly in soil from separate patches on the same site. When the interrelationships between soil parameters and reproduction were studied, it was not possible to create a good model of site soil toxicity based on single or even multiple chemical measurements of the soils. We thus conclude that chemical analysis alone is not sufficient to characterize soil quality and confirms the value of biological assays for risk assessment of potentially contaminated soils.

The ability of biomarkers to integrate effects of chemicals on biota has lead to increased calls for their application in assessing the status of polluted ecosystems. In tandem there has been an increase in our knowledge of the ecophysiological responses of keystone species to pollutants, which has allowed the development of a number of promising methods. In contrast to the number of biomarker development studies, the number of biomarker validation studies has remained limited. This paper redresses this imbalance by drawing together data from studies that have used the earthworm lysosomal membrane stability response (measured using the neutral red retention assay). This review first gives a short history of the biomarker's development. Second, it sets published applications of the technique against established criteria for a "good" biomarker (i.e., dose-response relationship, sensitivity, ecological relevance, confounding factors, chemical specificity, species differences, time-response relationship, methodological concerns, and overall public/regulator confidence, and acceptance). Discussion of the biomarker's suitability to each criterion is followed by an overall evaluation of its workability for routine soil quality assessment and caveats for its use.

At present there is little knowledge about how density regulates population growth rate and to what extent this is determined by life-history patterns. We compared density dependent population consequences in the Nicholsonian sense based oil experimental observations and life-history modeling for the earthworms Lumbricus terrestris and Eisenia fetida. Both species differ in their life-histories, L. terrestris being a relatively long-lived species with slow reproduction and occurring at low densities compared to E. Jetida which has a more opportunistic strategy with a high reproductive output. E.fetida is able to colonise new habitats rapidly and may occur at relatively high population densities. Density dependency of population growth rate was estimated by incorporating density dependent effects on reproduction and growth using a modified Euler equation. The results point out that E. fetida was not as strongly impacted by density as compared to L. terrestris. Population growth rate in E. fetida was hardly affected at low and moderate density, being reduced only at high level, this compares to L.terrestris where even relatively small density effects resulted in a strong negative effect on population growth rate. Our findings indicate that density-dependent regulation in earthworms can be quantified using life-history analysis. The outcomes are in agreement with empirical field observations for populations (i.e. L. terrestris occurs at low density, E. fetida at high density). Consideration of the potential importance of Nicholsonian density dependence for field populations of these two species in light of their known biology however produces counterintuitive conclusions. In E. fetida, although density tolerant, rapid population growth may mean this species may be subject to density dependent regulation. In L. terrestris, although density sensitive, complex behavioural ecology (surface activity, territoriality) may limit of feedback influence on population size.

To evaluate the impact of land-based contaminants on benthic faunas, as part of the Land-Ocean Contamination Study (LOCS), a study transect was established in Jakarta Bay, Indonesia during the 1996 southeasterly monsoon. The transect extended 72 km between the city's main port, Tanjung Priok, and the Pilau Seribu Island chain in the Java Sea. The dissolved concentrations of Pb, Cu, Zn, Cr and Ni in seawater, in suspended particulate matter (SPM) and surficial sea bed sediments were measured along the transect at nine sites. In addition, metal concentrations were measured in tissues of the corals Goniopora lobata and Lobophyllia hemprichii at five sites, and of the green mussel, Perna viridis at six sites. An assessment of the impact of contaminants on the faunas was made using a biomarker approach, employing coral community analysis and lysosomal stability with Perna viridis. The results of the study showed two main trends. The distributions of metals dissolved in seawater, in SPM, and in the coral and mussel tissues were similar, and failed to show a consistent graded response from inshore to offshore sites. This suggests that the concentration of metals in waters is the primary route for metal uptake by the coral and mussel tissues. By way of contrast, a clear offshore increase in coral generic diversity, coral cover, coral colony numbers and neutral-red retention time (lysosomal stability) was observed, aug gesting increasing nearshore stress. Whilst the coral community stucture may reflect the seasonally-averaged metal distributions in the bay (shown by the metal content of sea bed sediments which increase shorewards), it is more likely that the coral community structure and lysosomal biomarker are responding principally to other nearshore stresses, such as sediment and nutrient loading of water (sewage) or, more likely, organic contaminants such as oils and other hydrocarbons., Dans le cadre du programme Contamination Continent-Océan (LOCS, Land-Ocean Contamination Study), l'impact des contaminants terrestres sur la faune benthique du golfe de Djakarta (Indonésie) a été évalué en 1996, pendant la mousson du sud-est, sur une radiale de 72 km entre le port principal Tanjung Priok et la chaîne insulaire Pulau Seribu, dans la mer de Java. Les concentrations de Pb, Cu, Zn, Cr et Ni dissous ont été mesurées : 1) dans l'eau de mer, dans les particules en suspension et dans les sédiments superficiels (9 stations) ; 2) dans les tissus des coraux Goniopora lobata et Lobophyllia hemprichii (5 stations) ; 3) dans les tissus de la moule verte Perna viridis (6 stations). L'impact des contaminants sur la faune a été évalué à l'aide d'un marqueur biologique, par analyse de la communauté corallienne et stabilité lysosomiale avec Perna viridis. Deux tendances principales ressortent de cette étude. Les répartitions des métaux dissous dans l'eau de mer, dans les particules en suspension et dans les tissus des coraux et des moules sont similaires, sans variation entre la côte et le large, ce qui suggère que l'eau est la voie d'absorption des métaux par les tissus des coraux et des moules. À l'inverse, une nette augmentation est observée au large dans la diversité des genres coralliens, dans la couverture corallienne, dans le nombre des colonies de coraux et dans le temps de rétention du rouge-neutre (stabilité lysosomiale), ce qui indique un accroissement des contraintes vers la côte. Bien que la structure de la communauté corallienne représente la moyenne saisonnière de la répartition des métaux dans le golfe (illustrée par la teneur en métal des sédiments, croissante vers le rivage), il est probable que la structure de la communauté corallienne et le biomarqueur lysosomial répondent surtout à d'autres contraintes côtières, comme la charge en sédiments et en nutriments (égouts) ou, plus probablement, en contaminants organiques tels que le pétrole et les autres hydrocarbures.

Effects of nanoparticles on aquatic organisms have been little studied to date and toxicological data are urgently needed for development of regulatory frameworks for these substances. Here, we report the findings of a study exposing sticklebacks to cadmium sulfide (CdS) as bulk material and quantum dots. Fish were exposed for 21 d in a flow through test system to 5, 50 or 500 microg l(-1) CdS nanoparticles (nCdS) coated in thiol terminated methyl polyethylene glycol (MPEG), bulk CdS or MPEG at 500 microg l(-1) (nominal concentrations). With the exception of the highest nCdS exposure, measured concentrations were approximately one order of magnitude below nominal. A single fish from each group (excluding MPEG) was examined using energy dispersive X-ray analysis (EDX) to localise cadmium, however, cadmium could not be detected in whole body sections. Elevated levels of oxidized glutathione were measured in the gills of fish exposed to 50 and 500 microg l(-1) nCdS. Induction of vitellogenin synthesis was not detected in any of the treatment groups. The number of males engaged in nest-building behaviour following exposure to 500 microg l(-1) nCdS was reduced and livers of 4/6 fish in the same treatment displayed hepatocellular nuclear pleomorphism. The results are discussed emphasising the fundamental importance of experimental design and the need to understand the behaviour of nanoparticles in the aqueous phase.

Earthworms Lumbricus rubellus were exposed to a range of increasing soil copper concentrations in a mesocosm experiment for 17, 40, 70, and 110 days, respectively. Neutral-red retention times were measured along with earthworm tissue copper residues and earthworm growth and survival. The neutral-red retention assay demonstrated a clear dose-response threshold preceding a copper exposure value where increased regulatory activity had resulted in the copper bioconcentration factor (BCF) decreasing from 1 to 0.5. Effects on earthworm growth and survival occurred only at soil copper concentrations where the earthworm BCFs were lowered to ca. 0.5. Thus, the position of the neutral-red threshold could potentially make it possible to differentiate between copper exposure and actual toxicity. In terms of field applicability it was demonstrated that natural and seasonal variations in climatic parameters had little or no effect on the neutral-red response. Neutral-red retention assay has a potential role in environmental risk assessment and routine monitoring, as it is likely to provide a sufficiently accurate warning of impending ecological damage at a level below that found to cause actual physiological damage to the earthworms.

A simple earthworm biomarker, neutral-red retention by coelomocyte lysosomes, was measured concurrently with ecological parameters in order to link effects at different levels of biological organization in a laboratory study. Exposure of the earthworm Eisenia andrei to an increasing range of soil copper concentrations in the laboratory indicated a threshold range for the neutral-red assay at soil copper concentrations between 40 and 80 mg Cu kg-1. This threshold coincided with the soil to worm copper bioconcentration factor decreasing from 1 to 0.3 and thus an apparent onset of a copper regulatory mechanism. Effects at the individual and population levels only occurred at soil copper concentrations beyond that of the biomarker threshold. Thus, it was possible to differentiate between exposure and toxicity. It was therefore possible to conclude that the neutral-red assay has great potential and relevance in earthworm ecotoxicity studies. The assay provides an early warning that can be linked directly to important physiological changes that were observed to precede adverse effects on individuals or populations in this laboratory study.

A low-cost field technique employing retention of the dye neutral-red by lysosomes in coelomocyte cells taken from earthworms (Lumbricus castaneus), was used as a means of assessing the ecological effects (if any) of an industrial accident. Earthworms and soil samples were collected at the site of a large industrial plastics fire in Thetford, UK along a 200 m transect leading from the factory perimeter fence, over a layer of molten plastic impregnated soil and into the surrounding forest. Coelomic fluid extracted from the earthworms was dye-loaded with neutral-red and lysosomal leaking observed. Metal residues in soil and earthworms were found to be highly elevated close to the factory perimeter and to rapidly drop to background levels within the first 50 m of the transect. Coelomocyte cells taken from earthworms adjacent to the factory perimeter showed the shortest period of neutral-red retention (2 min); cells taken from worms further into the surrounding forest had a longer retention time (12 min), whilst cells taken from worms from a control site showed even greater retention times (25 min). Thus, the neutral-red retention times correlated negatively with measured residues of heavy metals in the earthworms, the higher the body metal concentration the shorter the retention time. This field trial has demonstrated the validity of using an in vitro cellular biomarker technique for use in biological impact assessment along gradients of contamination.

The effects of elevated copper concentrations and oxygen deficiency on total body copper concentration, egg-production and mortality of two genetically separated populations of Corophium volutator were studied. The amphipods were exposed for 14 days to a three-level factorial design of

The exuvial loss, subsequent uptake, and tissue and body distributions of the essential trace metals copper and zinc were investigated in an ecological series of talitrid amphipods, immediately after moult and throughout a post-moult period. Negligible quantities of copper or zinc were detected in cast exuvia of individual talitrids. Neither tissue nor whole body copper and zinc concentrations underwent significant changes during the moult cycle and all species showed extreme conservatism in their handling of body copper. There appeared to be no differential treatment of copper between species at the time of moult throughout the ecological series, with no obvious increase in copper retention by the more terrestrial species. The impact of moult cycle stage therefore is unlikely to affect the use of littoral talitrid amphipods as biomonitors for ambient copper and zinc concentrations.

The mode of metal accumulation employed by the terrestrial talitrid amphipod Arcitalitrus dorrieni (Hunt) feeding on leaf litter variously enriched with the essential metals copper and zinc have been established in the laboratory. Body concentrations of both metals were found to increase over time correlating with the increasing dietary metal concentrations. Field trials to assess the potential use of this amphipod as a terrestrial biomonitor for ambient copper and zinc availabilities in leaf litter are described. The results indicate a potential biomonitoring capacity for zinc (and possibly for copper also). The presently restricted distribution of this species, however, limits its biomonitoring potential to metalliferous areas of S.W. England, but reflects unknown potential in its native Australia.

In this study, the effects of two metals, copper and cadmium, on the growth and development of juvenile Lumbricus rubellus were measured in a toxicity test in which individuals were grown in isolation. This design had a number of advantages over traditional test systems for earthworms. Importantly, the test is specifically designed to measure two juvenile traits (survival over and length of the juvenile period) that have been shown to have a high sensitivity for determining population growth rate. The test system also maximizes replication, while allowing time-series-based monitoring of individual growth. For both metals, significant exposure-dependent effects on survival, growth, development time, and (less certainly) maturation weight were observed. Comparisons of the relative toxicity of the two metals indicated different concentration-response relationships. For copper, hormesis was found at low levels, while only at the highest soil concentration tested (10.07 micromol g(-1)) were (severe) toxic effects present. For cadmium, hormesis was also evident at the lowest concentration tested; however, at soil levels above this, a graded concentration-dependent toxic effect was apparent. These differences in the exposure response patterns can be (tentatively) explained in terms of the mechanisms for handling copper (an essential metal for earthworms) and cadmium (a putative nonessential element). The applicability of the test for routine measurement of chemical effects on ecologically relevant juvenile traits is also outlined and future developments are discussed.

19 F nuclear magnetic resonance (NMR) spectroscopy was used as a specific tool to investigate the metabolism of 3-trifluoromethylaniline (3-TFMA) in the earthworm species Eisenia veneta . Exposure was via a filter-paper contact toxicity test using five exposure levels (1000, 100, 10, 1, and 0.1 μg/cm 2 ). Instant lethality was observed at the two highest levels. Worms exposed at the lower levels appeared to tolerate the compound. The 19 F label of 3-TFMA allowed the uptake and metabolism of the earthworms to be monitored by 19 F NMR spectroscopy. Metabolism of 3-TFMA was observed at 10 μg/cm 2 and, to a lesser extent, at 1 μg/cm 2 . The possibility of 3-TFMA accumulation in specific organs was also investigated. As a simplified model, worms were cut into distinct anatomical regions (head, testes, crop, clitellum, and gut). At the two highest exposure levels, “uniform distribution” was observed. However, accumulation appeared to be proportional to the “size” of the extracted segments at the lower levels.

The endogenous metabolites of the coelomic fluid of the earthworm Eisenia veneta were characterised using high-resolution one-dimensional and two-dimensional 1H nuclear magnetic resonance spectroscopy. Signals from common organic acids, such as acetate, fumarate, malonate, malate, formate, and succinate, were identified together with adenosine and nicotinamide mononucleotide. The potential use of this information as a baseline dataset for future toxicological or physiological studies was demonstrated by a metabonomic analysis: a series of earthworms were dosed with the model compound 3-fluoro-4-nitrophenol, and toxic effects followed by multivariate analysis of the spectral data of the coelomic fluid. Relative concentrations of acetate and malonate were decreased in the dosed worms compared to the controls.

In models of insect–pathogen interactions, the transmission parameter (ν) is the term that describes the efficiency with which pathogens are transmitted between hosts. There are two components to the transmission parameter, namely the rate at which the host encounters pathogens (contact rate) and the rate at which contact between host and pathogen results in infection (host susceptibility). Here it is shown that in larvae of Spodoptera exempta (Lepidoptera: Noctuidae), in which rearing density triggers the expression of one of two alternative phenotypes, the high-density morph is associated with an increase in larval activity. This response is likely to result in an increase in the contact rate between hosts and pathogens. Rearing density is also known to affect susceptibility of S. exempta to pathogens, with the high-density morph showing increased resistance to a baculovirus. In order to determine whether density-dependent differences observed in the laboratory might affect transmission in the wild, a field trial was carried out to estimate the transmission parameter for S. exempta and its nuclear polyhedrosis virus (NPV). The transmission parameter was found to be significantly higher among larvae reared in isolation than among those reared in crowds. Models of insect–pathogen interactions, in which the transmission parameter is assumed to be constant, will therefore not fully describe the S. exempta-NPV system. The finding that crowding can influence transmission in this way has major implications for both the long-term population dynamics and the invasion dynamics of insect–pathogen systems.

A dual-labelling radioisotope technique has enabled the relative assimilation efficiencies of an essential (Zn) and a non-essential trace metal (Cd) to be determined in an ecological series of talitrid amphipods from low-shore to fully terrestrial habitats. All species exhibited high assimilation efficiencies for zinc and cadmium (within the range 66.7–96.4%). Interspecific differences in assimilation rates showed no trend with increasing terrestriality of the habitat. Elevated dietary zinc concentrations failed to enhance zinc assimilation efficiency. Incorporation of antibiotics into the diet to eliminate gut microflora did not affect zinc assimilation efficiencies. The implications of having high trace-metal assimilation efficiencies are discussed in terms of land invasion by talitrids.

Two species of talitrid amphipod Orchestia gammarellus (Pallas) and Orchestia mediterranea Costa were shown to accumulate copper and zinc from a range of copper- and zinc-enriched algal foods. Accumulation increased with increasing dietary metal concentrations. Laboratory results have been extrapolated to the field, in an attempt to compare the relative importance of food and solution as sources of trace metals to the talitrids in relation to their respective position on the shore. It was concluded that, for O. gammarellus, accumulation of copper from food was a more important route than the accumulation of copper from solution. O. mediterranea, however, was unable to satisfy its copper requirements from a food source, but was able to achieve all its copper requirements from solution