Trends in urolith composition and factors associated with different urolith types in dogs from the Republic of Ireland and Northern Ireland between 2010 and 2020.

OBJECTIVES: The purpose of this study was to determine changes in urolith trends and factors associated with different urolith types in dogs from the Republic of Ireland and Northern Ireland between 2010 and 2020. MATERIALS AND METHODS: A laboratory database was searched for canine urolith submissions between 2010 and 2020. Trends in urolith composition between 2014 and 2020, and associations between patient characteristics with each urolith type were evaluated. RESULTS: A total of 1162 submissions were included. Struvite (39.0%), calcium oxalate (27.8%) and compound (10.2%) were the most prevalent uroliths. Calcium oxalate urolith (CaOx) incidence significantly increased from 27.8% to 31.2% and that of struvite significantly decreased from 41.7% to 33.0% between 2014 and 2020. Struvite uroliths were overrepresented among females compared to males (odds ratio 8.7, 95% confidence interval 6.6 to 11.5). Males (odds ratio 9.6, 95% confidence interval 6.9 to 13.3) and dogs >7 years of age (odds ratio 4.1, 95%, confidence interval 3.0 to 5.4) were more likely to have CaOx while males (odds ratio 9.6, 95% confidence interval 5.3 to 17.8) and dogs ≤7 year of age, purine uroliths (odds ratio 3.0, 95% confidence interval 1.8 to 5.0). Incidence was higher in bichon frise (odds ratio 1.7, 95% confidence interval 1.3 to 2.4) and Yorkshire terrier (odds ratio 2.8, 95% confidence interval 1.9 to 4.1) for CaOx and higher in shih-tzu for compound uroliths (odds ratio 1.7, 95% confidence interval 1.1 to 2.7) compared to the remaining reported breeds. CLINICAL SIGNIFICANCE: Factors associated with different uroliths were similar to the ones previously reported. Proportion of CaOx submissions increased and that of struvite decreased over the study period which was in agreement with the changes identified in other European countries.

The ethical matrix as a method for involving people living with disease and the wider public (PPI) in near-term artificial intelligence research.

INTRODUCTION: The rapid pace of research in the field of Artificial Intelligence in medicine has associated risks for near-term AI. Ethical considerations of the use of AI in medicine remain a subject of much debate. Concurrently, the Involvement of People living with disease and the Public (PPI) in research is becoming mandatory in the EU and UK. The goal of this research was to elucidate the important values for our relevant stakeholders: People with MS, Radiologists, neurologists, Registered Healthcare Practitioners and Computer Scientists concerning AI in radiology and synthesize these in an ethical matrix. METHODS: An ethical matrix workshop co-designed with a patient expert. The workshop yielded a survey which was disseminated to the professional societies of the relevant stakeholders. Quantitative data were analysed using the Pingouin 0.53 python package. Qualitative data were examined with word frequency analysis and analysed for themes with grounded theory with a patient expert. RESULTS: 184 participants were recruited, (54, 60, 17, 12, 41 respectively). There were significant (p < 0.00001) differences in age, gender and ethnicity between groups. Key themes emerging from our results were the importance fast and accurate results, explanations over model performance and the significance of maintaining personal connections and choice. These themes were used to construct the ethical matrix. CONCLUSION: The ethical matrix is a useful tool for PPI and stakeholder engagement with particular advantages for near-term AI in the pandemic era. IMPLICATIONS FOR PRACTICE: We have produced an ethical matrix that allows for the inclusion of stakeholder opinion in medical AI research design.

Soil properties influence the toxicity and availability of Zn from ZnO nanoparticles to earthworms.

To develop models that support site-specific risk assessment for nanoparticles (NPs), a better understanding of how NP transformation processes, bioavailability and toxicity are influenced by soil properties is needed. In this study, the influence of differing soil properties on the bioavailability and toxicity of zinc oxide (ZnO) NPs and ionic Zn to the earthworm Eisenia fetida was investigated. Earthworms were exposed to ZnO_NPs and ionic Zn, between 100 and 4400 mg Zn/kg, in four different natural soils (organic matter content: 1.8-16.7%, soil pH: 5.4-8.3, representing sandy loam to calcareous soils). Survival and reproduction were assessed after 28 and 56 days, respectively. Zn concentrations in soil pore waters were measured while labile concentrations of Zn were measured using an in-situ dynamic speciation technique (diffusive gradient in thin films, DGT). Earthworm Zn tissue concentrations were also measured. Soil properties influenced earthworm reproduction between soil controls, with highest reproductive output in soils with pH values of 6-7. Toxicity was also influenced by soil properties, with EC50s based on total Zn in soil ranging from 694 to >2200 mg Zn/kg for ZnO_NP and 277-734 mg Zn/kg for ionic Zn. Soil pore water and DGT measurements showed good agreement in the relative amount of Zn extracted across the four soils. Earthworms exposed to ZnO_NPs survived higher Zn concentrations in the soils and had higher tissue concentrations compared with ionic Zn exposures, particularly in the high organic content calcareous soil. These higher tissue concentrations in ZnO_NP exposed earthworm could have consequences for the persistence and trophic mobility of Zn in terrestrial systems and need to be further investigated to elucidate if there any longer-term risks associated with sustained input of ZnO_NP to soil.

Designing rare disease care pathways in the Republic of Ireland: a co-operative model.

BACKGROUND: Rare diseases (RDs) are often complex, serious, chronic and multi-systemic conditions, associated with physical, sensory and intellectual disability. Patients require follow-up management from multiple medical specialists and health and social care professionals involving a high level of integrated care, service coordination and specified care pathways. METHODS AND OBJECTIVES: This pilot study aimed to explore the best approach for developing national RD care pathways in the Irish healthcare system in the context of a lack of agreed methodology. Irish clinical specialists and patient/lived experience experts were asked to map existing practice against evidence-based clinical practice guidelines (CPGs) and best practice recommendations from the European Reference Networks (ERNs) to develop optimal care pathways. The study focused on the more prevalent, multisystemic rare conditions that require multidisciplinary care, services, supports and therapeutic interventions. RESULTS: 29 rare conditions were selected across 18 ERNs, for care pathway development. Multidisciplinary input from multiple specialisms was relevant for all pathways. A high level of engagement was experienced from clinical leads and patient organisations. CPGs were identified for 26 of the conditions. Nurse specialist, Psychology, Medical Social Work and Database Manager roles were deemed essential for all care pathways. Access to the therapeutic Health Service Professionals: Physiotherapy, Occupational Therapy, and Speech and Language Therapy were seen as key requirements for holistic care. Genetic counselling was highlighted as a core discipline in 27 pathways demonstrating the importance of access to Clinical Genetics services for many people with RDs. CONCLUSIONS: This study proposes a methodology for Irish RD care pathway development, in collaboration with patient/service user advocates. Common RD patient needs and health care professional interventions across all pathways were identified. Key RD stakeholders have endorsed this national care pathway initiative. Future research focused on the implementation of such care pathways is a priority.

One-year parasitological screening of stray dogs and cats in County Dublin, Ireland.

To date, there are no recent studies identifying the prevalence of parasites of human and veterinary importance in dogs and cats in Ireland. The interaction between pets and wildlife species in the environment is an important source of parasite exposure to canids and felines, and one likely to be heightened in the stray animal population. This study aimed to establish the prevalence of endoparasites in unowned dogs and cats in County Dublin, Ireland. Feces from stray dogs (n = 627) and cats (n = 289) entering a rehoming centre were collected immediately after defecation. The main parasitic agents detected were ascarids (15.52 and 30.26%), Cystoisospora (3.27 and 3.69%), Giardia spp. (6.02 and 1.84%) and lungworms (0.64 and 2.08%), in dogs and cats respectively. Animals younger than 3 months of age were more likely to be infected with ascarids (P < 0.001) and Cystoisospora spp. (P = 0.008 and P = 0.014) than older animals. All lungworms were morphologically identified and dogs were infected with Angiostrongylus vasorum (0.48%) and Crenosoma vulpis (0.16%) whereas cats were only infected with Aelurostrongylus abstrusus (2.08%). This represents the first prevalence study of stray animals in Ireland. Data collected will inform the treatment and in addition, the future monitoring and control studies of parasite populations.

Development of a 22q11DS psycho-educational programme: exploration of the views, concerns and educational needs of parents caring for children or adolescents with 22q11DS in relation to mental health issues.

BACKGROUND: 22q11.2 deletion syndrome (22q11DS) is a multisystem genetic condition with a broad phenotype. It is associated with a high prevalence of depression and anxiety during childhood and increased risk of schizophrenia in adulthood. Despite this, studies report that families may receive inadequate information of mental health (MH) risks at diagnosis. Therefore, this study investigated parents' experiences of caring for a child with 22q11DS, investigated their knowledge regarding the risk of MH problems and assessed the need for a psycho-educational programme. METHODS: A qualitative design and purposeful sampling was utilized. Parents registered with the '22q11 Ireland' support group, and parents listed on the cleft palate database in a children's hospital in Ireland were invited to participate. Focus groups were held with 22 parents. Data were thematically analysed using Burnard's method of analysis. RESULTS: Most parents had some knowledge of the relationship between 22q11DS and an increased risk of MH issues. Parents reported that MH information relating to 22q11DS was mainly obtained from 22q11DS conferences, the '22q11 Ireland' support group and the Internet. Parents expressed a need for information to prevent or cope with their child's MH issues. Parents suggested that the following topics would be quite useful in a psycho-educational programme. These included information on the early warning signs of MH issues and guidance on when and how to tell the child about the condition and how to manage the child or young person's anxiety, obsessive behaviour or hearing voices. CONCLUSIONS: The findings indicated parental support for a psycho-educational programme that would provide relevant, accurate and timely information on how to effectively care for a child with 22q11DS MH needs.

Productivity in a dominant herbaceous species is largely unrelated to soil macronutrient stocks.

To predict ecosystem responses to anthropogenic change it is important to understand how and where plant productivity is limited by macronutrient availability. Nitrogen (N) is required in large quantities for plant growth, and is readily lost through leaching or gas fluxes, but reactive nitrogen can be obtained through dinitrogen fixation, and phosphorus (P) is often considered a more fundamental long-term constraint to growth and carbon sequestration in terrestrial ecosystems. Phosphorus limitation may be becoming more prevalent due to widespread pollution by atmospheric N. Assessments of the effects of macronutrient availability on productivity in natural ecosystems are however scarce. We measured standing biomass of bracken Pteridium aquilinum as a proxy for productivity across sites with similar climate but varied geology. Total above-ground biomass varied from 404 to 1947gm-2, yet despite 12-fold to 281-fold variation in soil macronutrient stocks these were remarkably poor at explaining variation in productivity. Soil total nitrogen, organic phosphorus, calcium, magnesium and zinc had no relationship with productivity, whether expressed as concentrations, stocks or element/C ratios, and nor did foliar N/P. Soil potassium (K) and molybdenum stocks both showed weak relationships with productivity. The stock of K in bracken biomass was considerably greater as a proportion of soil stock than for other nutrient elements, suggesting that this nutrient element can be important in determining productivity. Moisture availability, as indicated by environmental trait scores for plant species present, explained considerably more of the variation in productivity than did K stock, with less production in wetter sites. Soil N/C ratio and organic P stock were relatively unimportant in determining productivity across these bracken sites. It is possible that more-direct measures of N and P availability would explain variation in productivity, but the study shows the importance of considering other essential elements and other environmental factors when predicting productivity.

Atmospheric deposition of phosphorus to land and freshwater.

We compiled published and newly-obtained data on the directly-measured atmospheric deposition of total phosphorus (TP), filtered total phosphorus (FTP), and inorganic phosphorus (PO4-P) to open land, lakes, and marine coasts. The resulting global data base includes data for c. 250 sites, covering the period 1954 to 2012. Most (82%) of the measurement locations are in Europe and North America, with 44 in Africa, Asia, Oceania, and South-Central America. The deposition rates are log-normally distributed, and for the whole data set the geometric mean deposition rates are 0.027, 0.019 and 0.14 g m(-2) a(-1) for TP, FTP and PO4-P respectively. At smaller scales there is little systematic spatial variation, except for high deposition rates at some sites in Germany, likely due to local agricultural sources. In cases for which PO4-P was determined as well as one of the other forms of P, strong parallels between logarithmic values were found. Based on the directly-measured deposition rates to land, and published estimates of P deposition to the oceans, we estimate a total annual transfer of P to and from the atmosphere of 3.7 Tg. However, much of the phosphorus in larger particles (principally primary biological aerosol particles) is probably redeposited near to its origin, so that long-range transport, important for tropical forests, large areas of peatland and the oceans, mainly involves fine dust from deserts and soils, as described by the simulations of Mahowald et al. (Global Biogeochemical Cycles 22, GB4026, 2008). We suggest that local release to the atmosphere and subsequent deposition bring about a pseudo-diffusive redistribution of P in the landscape, with P-poor ecosystems, for example ombrotrophic peatlands and oligotrophic lakes, gaining at the expense of P-rich ones. Simple calculations suggest that atmospheric transport could bring about significant local redistribution of P among terrestrial ecosystems. Although most atmospherically transported P is natural in origin, local transfers from fertilised farmland to P-poor ecosystems may be significant, and this requires further research.

Life-history effects of arsenic toxicity in clades of the earthworm Lumbricus rubellus.

Exposures of Lumbricus rubellus to a series of arsenic concentrations in soil were used to assess life-stage (juvenile, adult) and genotype specific sensitivities, to calculate population growth rate (λ) and to assess patterns of As accumulation. Significant mortality was seen in juveniles at 125 mg/kg As, while growth and maturation was affected from 36 mg/kg and above. In adults, cocoon production at the highest concentration (125 mg/kg) was significantly reduced. Phylogenetic analysis was performed by comparison of mitochondrial sequences to establish genotypic variation among juveniles. Three clades with more than 7.5% divergent were described, with 70% of earthworms belonging to a single clade. Date of and mass at maturation was significantly different between clades, but clades were not differentially As sensitive. Parameter λ was reduced at 36 mg/kg As and was negative at 125 mg/kg As, suggesting impacts and population stability and potential extinction at environmentally relevant concentrations.

Role of riverine colloids in macronutrient and metal partitioning and transport, along an upland-lowland land-use continuum, under low-flow conditions.

An assessment is made of the role of riverine colloids in macronutrient (nitrogen, phosphorus and carbon), metal and trace element partitioning and transport, for five rivers in the Ribble and Wyre catchments in north-western England, under baseflow/near-baseflow conditions. Cross-flow ultrafiltration was used to separate colloidal (<0.45 µm >1 kDa) and truly dissolved (<1 kDa) fractions from river water. Clear patterns were observed, along the upland-lowland land use continuum, in the partitioning and transport of macronutrients and metals between the colloidal, truly dissolved and acid-available particulate (>0.45 µm, suspended) fractions. Of these operationally-defined fractions measured, colloids were generally more important for both macronutrient and metal transport in the upland than in the lowland rivers. The results suggest that organic moieties in truly dissolved form from sewage effluent may have a greater capacity to chelate metals. Organic-rich colloids in the upland moorlands and metal oxide colloidal precipitates in the industrial rivers had a higher capacity for binding metals than the colloidal fractions in the urban and agricultural lowland rivers. Aggregation of these colloids may provide an important mechanism for formation of larger suspended particulates, accounting for a higher degree of metal enrichment in the acid-available particulate fractions of the upland moorland and lowland industrial rivers, than in the lowland agricultural and urban rivers. This mechanism of transfer of contaminants to larger aggregates via colloidal intermediates, known as 'colloidal pumping' may also provide a mechanism for particulate P formation and the high proportion of P being transported in the particulate fraction in the uplands. The cross-flow ultrafiltration data also allowed refinement of partition coefficients, by accounting for colloids within the solids phase and replacing the filtered (<0.45 µm) fraction with the truly dissolved (<1 kDa) concentrations. These provided a clearer description of the controls on metal and P partitioning along the upland-lowland continuum.

Manganese in the upper Severn mid-Wales.

The concentrations of manganese (Mn) in the Upper River Severn (the Plynlimon catchments) are examined in relation to rainfall, cloud water, throughfall, stemflow and stream water concentrations where there is over 20 years of monitoring data available. Manganese concentrations are particularly low in rainfall and cloud water, with maximum concentrations occurring under low volumes of catch due to atmospheric "washout" of contaminants and dry deposition. There is strong Mn enrichment in throughfall and stemflow and this is probably linked to cycling through the vegetation. Manganese in the streams and groundwaters are primarily supplied from within-catchment sources. The highest concentrations occur within the tree canopy probably due to element cycling and in groundwaters due to mobilisation from the rock. Manganese concentrations in streams are at their lowest during spring and summer following long dry spells, with rapid increases following subsequent rain. There is no clear long-term trend in Mn concentration in the streams although there are increases in Mn concentrations for years when there is extensive felling of spruce plantation forest and in 1995 following a more extensive dry period. New high resolution monitoring picks up the effects of the rising limb of the hydrograph when concentrations rapidly increase, diurnal patterns during summer low-flow periods and contrasting dynamics between moorland and forested catchments.

Mercury in United Kingdom topsoils; concentrations, pools, and Critical Limit exceedances.

The median total mercury concentration in 898 UK rural topsoils, sampled between 1998 and 2008, was 0.095 µg g(-1). Approximate adjustment for unreactive metal produced an estimate of 0.052 µg g(-1) for reactive Hg. The highest concentrations were in the north and west, where organic-rich soils with low bulk densities dominate, but the spatial pattern was quite different if soil Hg pools (mg m(-2)) were considered, the highest values being near to the industrial north of England and London. Possible toxic effects of Hg were best evaluated by comparison with soil Critical Limits expressed as ratios of Hg to soil organic matter, or soil solution Hg(2+) concentrations, estimated by chemical speciation modelling. Only a few percent of the rural UK soils showed exceedance, and this also applied to rural soils from the whole of Europe. UK urban and industrial soils had higher Hg concentrations and more cases of exceedance.

The biogeochemistry of arsenic in a remote UK upland site: trends in rainfall and runoff, and comparisons with urban rivers.

Ten years of monitoring of rainfall and streams in the remote acidic and acid sensitive moorland and afforested moorland of upland mid-Wales reveals concentrations of arsenic (As) typically <1 µg L(-1). On average, the lowest concentrations occur within rainfall and they have declined over time probably in response to reductions in global emissions. There is a corresponding reduction within the streams except for forested systems where concentrations up to doubled following clear-fell. Within the streams there are both annual cycling and diurnal cycling of As. The annual cycling gives maxima during the summer months and this probably reflects the importance of groundwater inputs and mineralisation/desorption from the surface soil layers. Correspondingly, the diurnal cycling occurs during the summer months at low flow periods with As concentrations highest in the afternoon/evening. For the urban/industrial basins of northern England with historically a much higher As deposition, land contamination and effluent discharges, comparative data indicate As concentrations around three fold higher: strong seasonal patterns are observed for the same reasons as with the uplands. Across the sites, the As concentrations are over an order of magnitude lower than that of environmental concern. Nonetheless, the results clearly show the effects of declining emissions on rainfall deposition and some indication of areas of historic contamination. Arsenic is mainly present in the <0.45 fraction, but cross-flow filtration indicates that approx. 43% is in the colloidal phase at the clean water sites, and 16% in the colloidal phase at the contaminated sites. Part of this colloidal component may well be associated with organic carbon.

Background wet deposition of mercury in Great Britain.

Precipitation samples have been collected on a monthly basis from a network of 10 sites in Great Britain (GB) in order to estimate background mercury (Hg) deposition in the rural environment. Collection started in February 2005 and results presented here cover the period up to June 2009. The annual volume-weighted mean (AVWM) Hg concentrations range from 1.0 ng L(-1) at Cockley Beck in the Lake District in 2006 to 8.8 ng L(-1) at Heigham Holmes on the Norfolk Coast England in 2008. The largest validated solution concentrations were 33.7 ng L(-1) Hg measured at Cockley Beck in May 2008. The large difference in rainfall amount between sites means that the remote site at Cockley Beck has both the lowest long-term AVWM concentration (1.6 ng L(-1)) and the greatest annual flux is greatest at 43 mg ha(-1) yr(-1). Predicted deposition tends to be much greater in western Britain where the greater rainfall occurs. Because some observations are very close to the analytical detection limit (1.0 ng L(-1)), rigorous cleaning procedures, the use of replicate samplers to monitor contamination, and the inclusion of 'bottle blanks' are required to obtain valid measurements of Hg in the bulk deposition. Deposition in rural sites is equivalent to about 10% of the estimated magnitude of known emissions in GB.

Genetic diversity among Campylobacter jejuni isolates from pets in Ireland.

Campylobacter jejuni isolates obtained from pets housed in shelters and in private households were subtyped by fla typing (using DdeI and HinfI restriction enzymes) and pulsed-field gel electrophoresis (PFGE) techniques. Composite fla cluster analysis on 78 C jejuni isolates was more discriminative than either single fla typing technique with 39.7 per cent single isolate patterns. PFGE on 52 C jejuni isolates revealed 53.8 per cent single isolate patterns and was the most discriminative method applied. A database of C jejuni subtyping profiles from pets in Ireland was assembled. The presence of genetic heterogeneity detected in the C jejuni subtypes suggests that pets can acquire the organisms from multiple potential sources. In addition, heterogeneity was detected in the C jejuni subtypes obtained by different culture methods within the same pet. There was a link between isolates from dogs in close contact in the same environment, confirming that this is a potential route of infection, and clusters were detected containing both cat and dog C jejuni isolates, suggesting possible interspecies transmission.

Dynamic modelling of atmospherically-deposited Ni, Cu, Zn, Cd and Pb in Pennine catchments (northern England).

Simulation modelling with CHUM-AM was carried out to investigate the accumulation and release of atmospherically-deposited heavy metals (Ni, Cu, Zn, Cd and Pb) in six moorland catchments, five with organic-rich soils, one with calcareous brown earths, in the Pennine chain of northern England. The model considers two soil layers and a third layer of weathering mineral matter, and operates on a yearly timestep, driven by deposition scenarios covering the period 1400-2010. The principal processes controlling heavy metals are competitive solid-solution partitioning of solutes, chemical interactions in solution, and chemical weathering. Agreement between observed and simulated soil metal pools and surface water concentrations for recent years was generally satisfactory, the results confirming that most contemporary soil metal is from atmospheric pollution. Metals in catchments with organic-rich soils show some mobility, especially under more acid conditions, but the calcareous mineral soils have retained nearly all anthropogenic metal inputs. Complexation by dissolved organic matter and co-transport accounts for up to 80% of the Cu in surface waters.

Metal accumulation by stream bryophytes, related to chemical speciation.

Metal accumulation by aquatic bryophytes was investigated using data for headwater streams of differing chemistry. The Windermere Humic Aqueous Model (WHAM) was applied to calculate chemical speciation, including competitive proton and metal interactions with external binding sites on the plants. The speciation modelling approach gives smaller deviations between observed and predicted bryophyte contents of Cu, Zn, Cd and Pb than regressions based on total filtered metal concentrations. If all four metals, and Ni, are considered together, the WHAM predictions are superior at the 1% level. Optimised constants for bryophyte binding by the trace metals are similar to those for humic substances and simple carboxylate ligands. Bryophyte contents of Na, Mg and Ca are approximately explained by binding at external sites, while most of the K is intracellular. Oxide phases account for some of the Al, and most of the Mn, Fe and Co.

Simulating the long-term chemistry of an upland UK catchment: major solutes and acidification.

CHUM-AM was used to investigate changes in soil and water chemical variables in four moorland sub-catchments in Cumbria UK, to which non-marine S deposition has declined by 65% since the 1970s. The principal processes represented in the model comprise N and S uptake and release, water movements, the binding of cations by soil organic matter, chemical interactions in solution, and chemical weathering. CHUM-AM reproduced reasonably well the current soil pH and pools of N and S, and changes in streamwater chemistry over the period 1970-2000, notably decreases in the concentrations of alkaline earth cations and sulphate, and increases in pH. The model also predicts streamwater pH-Al relationships in agreement with observations. Predictive calculations suggest that constant atmospheric deposition of N at present rates will lead to N saturation and re-acidification, whereas a 50% reduction in N would stabilise soil and streamwater pH at about the present levels.

Simulating the long-term chemistry of an upland UK catchment: heavy metals.

CHUM-AM was used to investigate the behaviours of atmospherically-deposited heavy metals (Ni, Cu, Zn, Cd and Pb) in three moorland sub-catchments in Cumbria UK. The principal processes controlling cationic metals are competitive partitioning to soil organic matter, chemical interactions in solution, and chemical weathering. Metal deposition histories were generated by combining measured data for the last 30 years with local lake sediment records. For Ni, Cu, Zn and Cd, default parameters for the interactions with organic matter provided reasonable agreement between simulated and observed present-day soil metal pools and average streamwater concentrations. However, for Pb, the soil binding affinity in the model had to be increased to match the observations. Simulations suggest that weakly-sorbing metals (Ni, Zn, Cd) will respond on timescales of decades to centuries to changes in metal inputs or acidification status. More strongly-sorbing metals (Cu, Pb) will respond over centuries to millennia.

Potentially toxic metals in ombrotrophic peat along a 400 km English-Scottish transect.

Four samples of ombrotrophic peat were collected from each of 10 upland locations in a transect from the southern Pennines to the Highland Boundary Fault, a total distance of ca. 400 km. Bulk compositions and other properties were determined. Total contents of Al and heavy metals (Ni, Cu, Zn, Cd, Pb) were determined following digestion with hydrofluoric acid, and concentrations of metals extractable with dilute nitric acid were also measured. Supernatants obtained from aqueous extractions of the peat samples were analysed for pH, major cations and anions, dissolved organic carbon and dissolved metals, and concentrations of free metal ions (Al(3+), Ni(2+), etc.) were estimated by applying a chemical speciation model. Both total and HNO(3)-extractable metal concentrations varied along the transect, the highest values being found at locations close to industrial and former mining areas. The HNO(3)-extractable soil metal contents of Ni, Cu and Cd were appreciably lower than lowest-observed-effect-concentrations (LOEC) for toxicity towards microorganisms in acid, organic rich soils. However, the contents of Zn at two locations, and of Pb at five locations exceeded LOECs, suggesting that they may be exerting toxic effects in the peats. Soil solution concentrations of free heavy metal ions (Cu(2+), Zn(2+), Cd(2+), Pb(2+)) were substantially lower than LOECs for toxicity towards vascular plants, whereas concentrations of Al(3+) were near to toxic levels at two locations.