Weighted risk assessment of critical source areas for soil phosphorus losses through surface runoff mechanisms

This work was supported by the NERC QUADRAT DTP [grant number 2280708].Peer reviewedPublisher PD

Modelling the effectiveness of grass buffer strips in managing muddy floods under a changing climate

Muddy floods occur when rainfall generates runoff on agricultural land, detaching and transporting sediment into the surrounding natural and built environment. In the Belgian Loess Belt, muddy floods occur regularly and lead to considerable economic costs associated with damage to property and infrastructure. Mitigation measures designed to manage the problem have been tested in a pilot area within Flanders and were found to be cost-effective within three years. This study assesses whether these mitigation measures will remain effective under a changing climate. To test this, the Water Erosion Prediction Project (WEPP) model was used to examine muddy flooding diagnostics (precipitation, runoff, soil loss and sediment yield) for a case study hillslope in Flanders where grass buffer strips are currently used as a mitigation measure. The model was run for present day conditions and then under 33 future site-specific climate scenarios. These future scenarios were generated from three earth system models driven by four representative concentration pathways and downscaled using quantile mapping and the weather generator CLIGEN. Results reveal that under the majority of future scenarios, muddy flooding diagnostics are projected to increase, mostly as a consequence of large scale precipitation events rather than mean changes. The magnitude of muddy flood events for a given return period is also generally projected to increase. These findings indicate that present day mitigation measures may have a reduced capacity to manage muddy flooding given the changes imposed by a warming climate with an enhanced hydrological cycle. Revisions to the design of existing mitigation measures within existing policy frameworks are considered the most effective way to account for the impacts of climate change in future mitigation planni

Grassland Reseeding: Impact on Soil Surface Nutrient Accumulation and Using LiDAR-Based Image Differencing to Infer Implications for Water Quality

Publication history: Accepted - 2 November 2022; Published - 4 November 2022.Long-term phosphorus (P) accumulation in agricultural soils presents a challenge for water quality improvement. P is commonly elevated in soils managed for intensive livestock production due to repeated overapplication of slurry and fertilisers. High legacy nutrient accumulations result in poor water quality via transport pathways such as surface runoff, subsurface drainage, and soil erosion. To achieve environmental water quality targets, improved management strategies are required for targeting and reducing excess agricultural P sources. Reseeding of old swards is known to improve grassland productivity and enhance overall soil health. However, soil disturbance associated with reseeding could have positive and negative impacts on other soil functions that affect the nutrient balance (including improved microbial activity, but also increasing the potential for sediment and nutrient losses). This study investigates the impact of reseeding and inversion tillage in addressing soil surface nutrient surpluses and identifies potential trade-offs between production, environment (through soil erosion and associated sediment and nutrient losses), and soil health. At a study site in the Blackwater catchment in Northern Ireland, we collected highresolution (35 m) gridded soil samples pre- and post-reseeding for nutrient analyses and combined this with GIS-based interpolation. We found that decreases in sub-field scale surface nutrient content (0–7.5 cm depth) occurred following tillage and reseeding, but that this was spatially variable. In addition, the magnitude of changes in nutrient content was variable between P and other sampled nutrients. LiDAR-based image differencing indicated variability in the magnitude of soil erosion and sediment loss also at sub-field scale. Information on the identified deposition and erosion zones (from LiDAR analysis) was combined with mass wasting data to determine accumulation rates and losses of nutrients in-field and confirmed some of the identified patterns in soil surface nutrient content changes post-reseeding. We conclude that while inversion tillage and reseeding are essential agricultural practices, environmental trade-offs exist through potential nutrient and sediment losses. LiDAR-based image differencing was found to be a useful tool in helping to quantify these risks. Quantifying sediment and nutrient losses as a result of inversion tillage and reseeding induced soil erosion aids in understanding potential trends in water quality statuses.This research was funded by the NERC QUADRAT DTP, grant number 2280708

Grassland Reseeding - Improving Grassland Productivity and Reducing Excess Soil-Surface Nutrient Accumulations

Publication history: Published online 10 February 2022Long-term phosphorus (P) accumulation in agricultural soils presents a challenge for water quality improvement. P is commonly elevated in soils managed for intensive livestock production due to the repeated over-application of slurry and fertilizers. High legacy nutrient accumulations can result in poor water quality via transport pathways such as surface runoff, subsurface drainage, and soil erosion. To achieve the EU Water Framework Directive (WFD) aims, improved management strategies are required for diffuse and point P sources. Reseeding is known to improve grassland productivity and enhance overall soil health. However, soil disturbance associated with reseeding could have positive and negative effects on several other soil functions that affect the nutrient balance (including improved microbial activity, but also increasing the potential for sediment and nutrient losses). This study investigated the role of reseeding in addressing nutrient surpluses in surface soils and identified potential trade-offs between production, environment, and soil health. At a study site in the Blackwater catchment in Northern Ireland, we collected high-resolution gridded soil samples pre- and post-reseeding for nutrient analyses and combined this with GIS-based interpolation. We found that decreases in sub-field scale nutrient content occurred following reseeding, but that this was spatially variable. This indicates that this strategy is effective in reducing soil surface P accumulations. However, more research is needed to determine whether this P becomes available for grass uptake during re-growth or whether it increases the pool of mobile P, which can be lost in surface runoff, subsurface drainage, and soil erosionThis research was funded by the NERC QUADRAT DTP, grant number 2280708

Icy thermometers : quantifying the impact of volcanic heat on glacier elevation

ACKNOWLEDGEMENTS This project was supported by the NERC Global Partnerships Seedcorn grant NE/W003724/1 and the Leverhulme Trust Research Project RPG-2019-093. We thank Kevin A. Reath for support in analysing volcanic thermal anomalies. A.G.P. and M.E.P. were partly supported by the NASA Science Mission Directorate Earth Surface and Interior grant 80NSSC21K0842. J.J. was supported by the NERC Quadrat Doctoral Training Partnership. We express our gratitude to John Smellie and an anonymous reviewer for fruitful feedback which greatly improved the manuscript.Peer reviewedPostprin

60 million years of glaciation in the Transantarctic Mountains

The Antarctic continent reached its current polar location ~83 Ma and became shrouded by ice sheets ~34 Ma, coincident with dramatic global cooling at the Eocene-Oligocene boundary. However, it is not known whether the first Antarctic glaciers formed immediately prior to this or were present significantly earlier. Here we show that mountain glaciers were likely present in the Transantarctic Mountains during the Late Palaeocene (~60–56 Ma) and middle Eocene (~48–40 Ma). Temperate (warm-based) glaciers were prevalent during the Late Eocene (~40–34 Ma) and, in reduced numbers, during the Oligocene (~34–23 Ma), before larger, likely cold-based, ice masses (including ice sheets) dominated. Some temperate mountain glaciers were present during the Miocene Climatic Optimum (~15 Ma), before a widespread switch to cold-based glaciation. Our findings highlight the longevity of glaciation in Antarctica and suggest that glaciers were present even during the Early-Cenozoic greenhouse world

Utility of Phase Angle to Identify Cachexia and Assess Mortality in End-Stage Renal Disease

© 2020 American Society for Nutrition. Published by Elsevier Inc. This is an Open access article under the CC-BY-NC-ND license. https://creativecommons.org/licenses/by-nc-nd/4.0/Objectives This cross-sectional analysis sought to identify cachexia and assess survival using phase angle (PA) in patients with end-stage renal disease (ESRD) receiving haemodialysis. Methods Patients receiving haemodialysis (n = 87, mean age 65.9 +/– 13.0) completed a Phase Angle (PA; 50 khz) measurement using bioelectrical impedance analysis. Cachexia variables were recorded according to Evans et al. definition (2008) including nutritional and functional measures (weight, Body Mass Index (BMI), Hand Grip Strength (HGS), Lean Tissue Mass (LTM), C-Reative Protein (CRP), serum albumin, haemoglobin, appetite (Functional Assessment of Anorexia/Cachexia Treatment (FAACT)) and fatigue (Functional Assessment of Chronic Illness Therapy (FACIT)). Survival was assessed at 12 months. Mann Whitney-U and Spearman correlation coefficient were conducted. Results The majority of patients completed follow up (n = 76). Eleven patients had died. Mean PA was not statistically different between those identified as cachectic and non-cachectic according to Evans et al. (2008) definition or between those patients that survived and died. However, patients that survived had better mean scores of weight, BMI, HGS, CRP, serum albumin and fatigue (FACIT). In addition, LTM scores were significantly better in patients that survived (P < .01). Appetite scores were also significantly better in patients that survived (P < .01) and those without cachexia (P = .01). Conclusions This study was part of a larger effort to clarity a phenotype of cachexia in ESRD. Unlike previous research, this study did not find PA useful in identifying patients at a higher risk of cachexia or death. However overall these patients had a very low mean PA. FAACT did discriminate between groups indicating self-reporting measurement tools of nutritional status were useful in identifying patients at a higher risk of cachexia and death. A larger sample and longer follow up is required to balance the limitations of this small study. Timing the administration of PA also requires consideration in future studies. Funding Sources Public Health Agency; Northern Ireland Kidney Research Fund.Peer reviewe

Using a generic definition of cachexia in patients with kidney disease receiving haemodialysis: a longitudinal (pilot) study

International audienceBACKGROUND: Research indicates that cachexia is common among persons with chronic illnesses and is associated with increased morbidity and mortality. However, there continues to be an absence of a uniformed disease-specific definition for cachexia in chronic kidney disease (CKD) patient populations. OBJECTIVE: The primary objective was to identify cachexia in patients receiving haemodialysis (HD) using a generic definition and then follow up on these patients for 12 months. METHOD: This was a longitudinal study of adult chronic HD patients attending two hospital HD units in the UK. Multiple measures relevant to cachexia, including body mass index (BMI), muscle mass [mid-upper arm muscle circumference (MUAMC)], handgrip strength (HGS), fatigue [Functional Assessment of Chronic Illness Therapy (FACIT)], appetite [Functional Assessment of Anorexia/Cachexia Therapy (FAACT)] and biomarkers [C-reactive protein (CRP), serum albumin, haemoglobin and erythropoietin resistance index (ERI)] were recorded. Baseline analysis included group differences analysed using an independent t-test, dichotomized values using the χ2 test and prevalence were reported using the Statistical Package for the Social Sciences 24 (IBM, Armonk, NY, USA). Longitudinal analysis was conducted using repeated measures analysis. RESULTS: A total of 106 patients (30 females and 76 males) were recruited with a mean age of 67.2 years [standard deviation (SD) 13.18] and dialysis vintage of 4.92 years (SD 6.12). At baseline, 17 patients were identified as cachectic, having had reported weight loss (e.g. \textgreater5% for \textgreater6 months) or BMI \textless20 kg/m2 and three or more clinical characteristics of cachexia. Seventy patients were available for analysis at 12 months (11 cachectic versus 59 not cachectic). The FAACT and urea reduction ratio statistically distinguished cachectic patients (P = 0.001). However, measures of weight, BMI, MUAMC, HGS, CRP, ERI and FACIT tended to worsen in cachectic patients. CONCLUSION: Globally, cachexia is a severe but frequently underrecognized problem. This is the first study to apply the defined characteristics of cachexia to a representative sample of patients receiving HD. Further, more extensive studies are required to establish a phenotype of cachexia in advanced CKD

Icy thermometers: quantifying the impact of volcanic heat on glacier elevation

We present a continent-wide study of 600 glaciers located on and near 37 ice-clad volcanoes in South America, that demonstrates glacier sensitivity to volcanic heat. We distinguish between ‘volcanic-glaciers’ (≤1 km from volcanic centres; n=74), and ‘proximal glaciers’ (1-15 km; n=526) and calculate their equilibrium line altitudes (ELA). For each ice-clad volcano we compare the ELAs of its volcanic-glaciers to those of its proximal glaciers which shows that the ELAs of the former are higher than the ELAs of the latter. ΔELAmean, defined as the offset between the mean ELA of the volcanic-glaciers and that of the proximal glaciers, is calculated for each ice-clad volcano. ΔELAmean is positive for 92% of the 37 volcanoes, and a quantitative relationship between ΔELAmean and volcanic thermal anomaly is established. Results highlight the impact of volcanic heat on glacier elevation; emphasise the need to exclude glaciers on, or near, volcanoes from glacier-climate investigations; and demonstrate the first-order potential for glaciers as ‘volcanic thermometers’. Volcanic-glacier monitoring could contribute to our understanding of magmatic and thermal activity, with changes in glacier geometries potentially reflecting long-term fluctuations in volcanic heat and unrest

Climate change and the long-term viability of the World’s busiest heavy haul ice road

Climate models project that the northern high latitudes will warm at a rate in excess of the global mean. This will pose severe problems for Arctic and sub-Arctic infrastructure dependent on maintaining low temperatures for structural integrity. This is the case for the economically important Tibbitt to Contwoyto Winter Road (TCWR)—the world’s busiest heavy haul ice road, spanning 400 km across mostly frozen lakes within the Northwest Territories of Canada. In this study, future climate scenarios are developed for the region using statistical downscaling methods. In addition, changes in lake ice thickness are projected based on historical relationships between measured ice thickness and air temperatures. These projections are used to infer the theoretical operational dates of the TCWR based on weight limits for trucks on the ice. Results across three climate models driven by four RCPs reveal a considerable warming trend over the coming decades. Projected changes in ice thickness reveal a trend towards thinner lake ice and a reduced time window when lake ice is at sufficient thickness to support trucks on the ice road, driven by increasing future temperatures. Given the uncertainties inherent in climate modelling and the resultant projections, caution should be exercised in interpreting the magnitude of these scenarios. More certain is the direction of change, with a clear trend towards winter warming that will reduce the operation time window of the TCWR. This illustrates the need for planners and policymakers to consider future changes in climate when planning annual haulage along the TCWR