Perceptions of mental health providers of the barriers and facilitators of using and engaging youth in digital mental-health-enabled measurement based care.

Objectives: Increased rates of mental health disorders and substance use among youth and young adults have increased globally, furthering the strain on an already burdened mental health system. Digital solutions have been proposed as a potential option for the provision of timely mental health services for youth, with little research exploring mental health professional views about using such innovative tools. In Alberta, Canada, we are evaluating the implementation and integration of a digital mental health (dMH) platform into existing service pathways. Within this paper we seek to explore mental health professionals' perceptions of the barriers and facilitators that may influence their utilization of digital MH-enabled measurement-based care (MBC) with the youth who access their services. Methods: A qualitative, descriptive methodology was used to inductively generate themes from focus groups conducted with mental health professionals from specialized mental health services and primary care networks in Alberta. Results: As mental health professionals considered the barriers and facilitators of using dMH with youth, they referenced individual and family barriers and facilitators to consider. Providers highlighted perceived barriers, including: first, cultural stigma, family apprehension about mental health care, and parental access to dMH and MBC as deterrents to providers adopting digital platforms in routine care; second, perceptions of increased responsibility and liability for youth in crisis; third, perception that some psychiatric and neurodevelopmental disorders in youth are not amenable to dMH; fourth, professionals contemplated youth readiness to engage with dMH-enabled MBC. Participants also highlighted pertinent facilitators to dMH use, noting: first, the suitability of dMH for youth with mild mental health concerns; second, youth motivated to report their changes in mental health symptoms; and lastly, youth proficiency and preference for dMH options. Conclusions: By identifying professionals' perceptions of barriers and facilitators for youth users, we may better understand how to address misconceptions about who is eligible and appropriate for dMH through training and education.

Study protocol for The GOAL Trial: comprehensive geriatric assessment for frail older people with chronic kidney disease to increase attainment of patient-identified goals-a cluster randomised controlled trial.

BACKGROUND: An increasing number of older people are living with chronic kidney disease (CKD). Many have complex healthcare needs and are at risk of deteriorating health and functional status, which can adversely affect their quality of life. Comprehensive geriatric assessment (CGA) is an effective intervention to improve survival and independence of older people, but its clinical utility and cost-effectiveness in frail older people living with CKD is unknown. METHODS: The GOAL Trial is a pragmatic, multi-centre, open-label, superiority, cluster randomised controlled trial developed by consumers, clinicians, and researchers. It has a two-arm design, CGA compared with standard care, with 1:1 allocation of a total of 16 clusters. Within each cluster, study participants ≥ 65 years of age (or ≥ 55 years if Aboriginal or Torres Strait Islander (First Nations Australians)) with CKD stage 3-5/5D who are frail, measured by a Frailty Index (FI) of > 0.25, are recruited. Participants in intervention clusters receive a CGA by a geriatrician to identify medical, social, and functional needs, optimise medication prescribing, and arrange multidisciplinary referral if required. Those in standard care clusters receive usual care. The primary outcome is attainment of self-identified goals assessed by standardised Goal Attainment Scaling (GAS) at 3 months. Secondary outcomes include GAS at 6 and 12 months, quality of life (EQ-5D-5L), frailty (Frailty Index - Short Form), transfer to residential aged care facilities, cost-effectiveness, and safety (cause-specific hospitalisations, mortality). A process evaluation will be conducted in parallel with the trial including whether the intervention was delivered as intended, any issue or local barriers to intervention delivery, and perceptions of the intervention by participants. The trial has 90% power to detect a clinically meaningful mean difference in GAS of 10 units. DISCUSSION: This trial addresses patient-prioritised outcomes. It will be conducted, disseminated and implemented by clinicians and researchers in partnership with consumers. If CGA is found to have clinical and cost-effectiveness for frail older people with CKD, the intervention framework could be embedded into routine clinical practice. The implementation of the trial's findings will be supported by presentations at conferences and forums with clinicians and consumers at specifically convened workshops, to enable rapid adoption into practice and policy for both nephrology and geriatric disciplines. It has potential to materially advance patient-centred care and improve clinical and patient-reported outcomes (including quality of life) for frail older people living with CKD. TRIAL REGISTRATION: ClinicalTrials.gov NCT04538157. Registered on 3 September 2020.

Development of a deuterium-ice extruder for inertial confinement fusion experiments on the Z Facility.

A deuterium-ice extruder has been developed for inertial confinement fusion experiments on the Sandia National Laboratories Z Facility. The screw-driven extruder is filled via desublimation, where a slow flow of deuterium gas enters the extruder cavity and freezes to the walls without entering the liquid phase. Ice generated in this manner is optically clear, demonstrating its high uniformity. When the extruder cavity is filled with ice, the screw is driven downward, closing off the gas-fill line. With the ice cavity isolated, further screw rotation compresses the deuterium through a nozzle, extruding a fiber. Fiber diameters ranging from 200 to 500 µm have been extruded to lengths of 1.5 feet before hitting the vacuum chamber floor. The fiber straightness improves with the nozzle length-to-diameter aspect ratio. Deuterium-ice fibers can persist in high vacuum for more than 10 min before breaking free from the nozzle. The peripheral infrastructure required for Z experimental operations is under development. An in-vacuum stepper-motor-based drive system will allow remote operation, and a translating cathode will ensure proper placement of the fiber in the powerflow hardware.

Postoperative outcomes after bariatric surgery in patients on chronic dialysis: A systematic review and meta-analysis.

BACKGROUND: Obesity is a barrier to kidney transplantation for patients with kidney failure. Consequently, bariatric surgery is often considered as a bridge to transplantation, even though its risks and benefits are poorly characterised in the dialysis population. METHODS: Systematic searches of observational studies indexed in Embase, MEDLINE and CENTRAL till April 2020 were performed to identify relevant studies. Risk of bias was assessed by the Newcastle Ottawa Scale and quality of evidence was summarised in accordance with GRADE methodology. Random effects meta-analyses were performed to obtain summary odds ratios for postoperative outcomes. RESULTS: Four cohort studies involving 4196 chronic dialysis and 732,204 non-dialysis patients undergoing bariatric surgery were included. Sleeve gastrectomy (61%), and Roux-en-Y gastric bypass (29%) were the most common procedures performed. Absolute rates of adverse events were low, but the odds of postoperative mortality (0.4-0.5% vs. 0.1%; odds ratio [OR] 4.7, 95%CI 2.2-9.9), and myocardial infarction (0.0-0.5% vs. 0.1%, OR 3.4, 95% CI 2.0-5.9) were higher in dialysis compared to non-dialysis patients. Patients on dialysis also had more than 2-fold increased odds of returning to theatre and having a readmission. Rates of kidney transplant wait-listing among dialysis patients was 59%, with 28% of all patients eventually receiving a kidney transplant. CONCLUSION: Patients receiving chronic dialysis have substantially increased odds of postoperative mortality and myocardial infarction following bariatric surgery compared with patient who do not have kidney failure. It is uncertain whether bariatric surgery improves the likelihood of kidney transplantation, with mid- to long-term outcomes being poorly described.

Design and methods of the REMOVAL-HD study: a tRial Evaluating Mid cut-Off Value membrane clearance of Albumin and Light chains in HaemoDialysis patients.

BACKGROUND: Removal of uraemic toxins is inadequate using current dialysis strategies. A new class of dialysis membranes have been developed that allow clearance of larger middle molecules. The REMOVAL-HD study (a tRial Evaluating Mid cut-Off Value membrane clearance of Albumin and Light chains in HaemoDialysis patients) will address safety, efficacy and the impact on patient-centred outcomes with the use of a mid cut-off (MCO) dialyser in a chronic haemodialysis (HD) population. METHODS: REMOVAL-HD is an open label, prospective, non-randomised, single-arm, multi-centre device study in 85 chronic HD participants. All visits will be conducted during regular HD sessions and participants will undergo a 1 month wash-in period using a standardised high flux dialyser, 6 months of intervention with a MCO dialyser and 1 month of wash-out using a high flux dialyser. The primary endpoint is change in pre-dialysis concentrations of serum albumin, with secondary endpoints including the efficacy of clearance of free light chains and ß-2 microglobulin, and patient-centred outcomes including quality of life, symptom burden, functional status, nutritional status, hospitalisation and death. DISCUSSION: MCO dialysers are a novel form of HD membrane. The REMOVAL-HD study is a pivotal study designed to monitor the immediate and medium-term effects following exposure to this dialyser. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry Number (ANZCTRN) 12616000804482 . Date of registration - 21/06/2016.

Evaluation of sedation-related medication errors in patients on contact isolation in the intensive care unit.

BACKGROUND: Patients in intensive care units (ICUs) may be placed on contact isolation for meticillin-resistant Staphylococcus aureus (MRSA) colonization to prevent transmission. Prior studies suggest that isolated patients may receive substandard care compared with non-isolated patients. An optimal level of sedation is required to facilitate mechanical ventilation (MV) and to minimize adverse outcomes. AIM: To determine if patients on MV and isolated for MRSA colonization are at increased risk of oversedation compared with non-isolated patients. METHODS: Retrospective chart review of adult patients on MV who received an MRSA nasal polymerase chain reaction assay and sedation within 24 and 48 h of ICU admission, respectively. Endpoints included rate of inappropriate sedation, length of ICU stay, length of time on MV, and incidence of ventilator-associated complications. FINDINGS: In total, 226 patients were included (114 MRSA positive, 112 MRSA negative). Baseline demographics were similar between the groups, with the exception of ICU admission diagnosis. Fifty-six (55%) isolated patients experienced inappropriate sedation compared with 49 (50%) non-isolated patients (P=0.482). Isolated patients spent longer in the ICU (10.4 vs 6.8 days, P=0.0006), longer on MV (8.98 vs 4.81 days, P<0.001), and required tracheostomies more frequently [37 (32%) vs 14 (13%), P=0.0003] than non-isolated patients. CONCLUSIONS: Isolated patients were not at increased risk of oversedation compared with non-isolated patients. There was an association between the use of contact isolation for MRSA nares colonization and prolonged ICU stay and prolonged MV.

Incidence and Predictors of Cancer Following Kidney Transplantation in Childhood.

Cancer risk is increased substantially in adult kidney transplant recipients, but the long-term risk of cancer in childhood recipients is unclear. Using the Australian and New Zealand Dialysis and Transplant Registry, the authors compared overall and site-specific incidences of cancer after transplantation in childhood recipients with population-based data by using standardized incidence ratios (SIRs). Among 1734 childhood recipients (median age 14 years, 57% male, 85% white), 289 (16.7%) developed cancer (196 nonmelanoma skin cancers, 143 nonskin cancers) over a median follow-up of 13.4 years. The 25-year cumulative incidences of any cancer were 27% (95% confidence intervals 24-30%), 20% (17-23%) for nonmelanoma skin cancer, and 14% (12-17%) for nonskin cancer (including melanoma). The SIR for nonskin cancer was 8.23 (95% CI 6.92-9.73), with the highest risk for posttransplant lymphoproliferative disease (SIR 45.80, 95% CI 32.71-62.44) and cervical cancer (29.4, 95% CI 17.5-46.5). Increasing age at transplantation (adjusted hazard ratio [aHR] per year 1.10, 95% CI 1.06-1.14), white race (aHR 3.36, 95% CI 1.61-6.79), and having a functioning transplant (aHR 2.27, 95% CI 1.47-3.71) were risk factors for cancer. Cancer risk, particularly for virus-related cancers, is increased substantially after kidney transplantation during childhood.

Genetic diversity affects the strength of population regulation in a marine fish.

Variation is an essential feature of biological populations, yet much of ecological theory treats individuals as though they are identical. This simplifying assumption is often justified by the perception that variation among individuals does not have significant effects on the dynamics of whole populations. However, this perception may be skewed by a historic focus on studying single populations. A true evaluation of the extent to which among-individual variation affects the dynamics of populations requires the study of multiple populations. In this study, we examined variation in the dynamics of populations of a live-bearing, marine fish (black surfperch; Embiotoca jacksoni). In collaboration with an organization of citizen scientists (Reef Check California), we were able to examine the dynamics of eight populations that were distributed throughout approximately 700 km of coastline, a distance that encompasses much of this species' range. We hypothesized that genetic variation within a local population would be related to the intensity of competition and to the strength of population regulation. To test this hypothesis, we examined whether genetic diversity (measured by the diversity of mitochondrial DNA haplotypes) was related to the strength of population regulation. Low-diversity populations experienced strong density dependence in population growth rates and population sizes were regulated much more tightly than they were in high-diversity populations. Mechanisms that contributed to this pattern include links between genetic diversity, habitat use, and spatial crowding. On average, low-diversity populations used less of the available habitat and exhibited greater spatial clustering (and more intense competition) for a given level of density (measured at the scale of the reef). Although the populations we studied also varied with respect to exogenous characteristics (habitat complexity, densities of predators, and interspecific competitors), none of these characteristics was significantly related to the strength of population regulation. In contrast, an endogenous characteristic of the population (genetic diversity) explained 77% of the variation in the strength of population regulation (95% CI: 27-94%). Our results suggest that the genetic and phenotypic composition of populations can play a major role in their dynamics.

Distortion of Chain Conformation and Reduced Entanglement in Polymer-Graphene Oxide Nanocomposites.

We study the conformations of polymer chains in polymer-graphene oxide nanocomposites. We show that the chains have a reduced radius of gyration that is consistent with confinement at a solid interface in the melt, as is expected for well-dispersed, high aspect ratio nanoparticles that are much larger than the polymer coil size. We show that confinement of the polymer chains causes a corresponding reduction in interchain entanglements, and we calculate a contribution to the plateau modulus from the distorted polymer network via a simple scaling argument. Our results are a significant step forward in understanding how two-dimensional nanoparticles affect global material properties at low loadings.

Lepidoptera (Crambidae, Noctuidae, and Pyralidae) Injury to Corn Containing Single and Pyramided Bt Traits, and Blended or Block Refuge, in the Southern United States.

Fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae); corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae); southwestern corn borer, Diatraea grandiosella Dyar (Lepidoptera: Crambidae); sugarcane borer, Diatraea saccharalis F. (Lepidoptera: Crambidae); and lesser cornstalk borer, Elasmopalpus lignosellus Zeller (Lepidoptera: Pyralidae), are lepidopteran pests of corn, Zea mays L., in the southern United States. Blended refuge for transgenic plants expressing the insecticidal protein derivative from Bacillus thuringiensis (Bt) has recently been approved as an alternative resistance management strategy in the northern United States. We conducted a two-year study with 39 experiments across 12 states in the southern United States to evaluate plant injury from these five species of Lepidoptera to corn expressing Cry1F and Cry1Ab, as both single and pyramided traits, a pyramid of Cry1Ab×Vip3Aa20, and a pyramid of Cry1F×Cry1Ab plus non-Bt in a blended refuge. Leaf injury and kernel damage from corn earworm and fall armyworm, and stalking tunneling by southwestern corn borer, were similar in Cry1F×Cry1Ab plants compared with the Cry1F×Cry1Ab plus non-Bt blended refuge averaged across five-plant clusters. When measured on an individual plant basis, leaf injury, kernel damage, stalk tunneling (southwestern corn borer), and dead or injured plants (lesser cornstalk borer) were greater in the blended non-Bt refuge plants compared to Cry1F×Cry1Ab plants in the non-Bt and pyramided Cry1F×Cry1Ab blended refuge treatment. When non-Bt blended refuge plants were compared to a structured refuge of non-Bt plants, no significant difference was detected in leaf injury, kernel damage, or stalk tunneling (southwestern corn borer). Plant stands in the non-Bt and pyramided Cry1F×Cry1Ab blended refuge treatment had more stalk tunneling from sugarcane borer and plant death from lesser cornstalk borer compared to a pyramided Cry1F×Cry1Ab structured refuge treatment. Hybrid plants containing Cry1F×Cry1Ab within the pyramided Cry1F×Cry1Ab blended refuge treatment had significantly less kernel damage than non-Bt structured refuge treatments. Both single and pyramided Bt traits were effective against southwestern corn borer, sugarcane borer, and lesser cornstalk borer.

Dietary protein-fiber ratio associates with circulating levels of indoxyl sulfate and p-cresyl sulfate in chronic kidney disease patients.

BACKGROUND AND AIMS: Indoxyl sulfate (IS) and p-cresyl sulfate (PCS) are uremic toxins derived solely from colonic bacterial fermentation of protein. Dietary fiber may counteract this by limiting proteolytic bacterial fermentation. However, the influence of dietary intake on the generation of IS and PCS has not been adequately explored in chronic kidney disease (CKD). METHODS AND RESULTS: This cross-sectional study included 40 CKD participants (60% male; age 69 ± 10 years; 45% diabetic) with a mean estimated glomerular filtration rate (eGFR) of 24 ± 8 mL/min/1.73 m(2), who enrolled in a randomized controlled trial of synbiotic therapy. Total and free serum IS and PCS were measured at baseline by ultra-performance liquid chromatography. Dietary intake was measured using in-depth diet histories collected by a dietitian. Associations between each toxin, dietary fiber (total, soluble and insoluble), dietary protein (total, and amino acids: tryptophan, tyrosine and phenylalanine), and the protein-fiber index (ratio of protein to fiber) were assessed using linear regression. Dietary fiber was associated with free and total serum PCS (r = -0.42 and r = -0.44, both p < 0.01), but not IS. No significant association was observed between dietary protein and either toxin. The protein-fiber index was associated with total serum IS (r = 0.40, p = 0.012) and PCS (r = 0.43, p = 0.005), independent of eGFR, sex and diabetes. CONCLUSION: Dietary protein-fiber index is associated with serum IS and PCS levels. Such association, beyond fiber and protein alone, highlights the importance of the interplay between these nutrients. We speculate that dietary modification towards a lower protein-fiber index may contribute to lowering IS and PCS.

Using post-settlement demography to estimate larval survivorship: a coral reef fish example.

Many species have multi-stage life cycles in which the youngest stages (e.g., larvae) are small, dispersive, and abundant, whereas later stages are sessile or sedentary. Quantifying survival throughout such early stages is critical for understanding dispersal, population dynamics, and life history evolution. However, dispersive stages can be very difficult to sample in situ, and estimates of survival through the entire duration of these stages are typically poor. Here we describe how demographic information from juveniles and adults can be used to estimate survival throughout a dispersive larval stage that was not sampled directly. Using field measurements of demography, we show that detailed information on post-settlement growth, survival, and reproduction can be used to estimate average larval survivorship under the assumption that a typical individual replaces itself over its lifetime. Applying this approach to a common coral reef fish (bicolor damselfish, Stegastes partitus), we estimated average larval survivorship to be 0.108% (95% CI 0.025-0.484). We next compared this demography-based estimate to an expected value derived from published estimates of larval mortality rates. Our estimate of larval survivorship for bicolor damselfish was approximately two orders of magnitude greater than what would be expected if larval mortality of this species followed the average, size-dependent pattern of mortality inferred from a published sample of marine fishes. Our results highlight the importance of understanding mortality during the earliest phases of larval life, which are typically not sampled, as well as the need to understand the details of how larval mortality scales with body size.

X-ray power and yield measurements at the refurbished Z machine.

Advancements have been made in the diagnostic techniques to measure accurately the total radiated x-ray yield and power from z-pinch implosion experiments at the Z machine with high accuracy. The Z machine is capable of outputting 2 MJ and 330 TW of x-ray yield and power, and accurately measuring these quantities is imperative. We will describe work over the past several years which include the development of new diagnostics, improvements to existing diagnostics, and implementation of automated data analysis routines. A set of experiments on the Z machine were conducted in which the load and machine configuration were held constant. During this shot series, it was observed that the total z-pinch x-ray emission power determined from the two common techniques for inferring the x-ray power, a Kimfol filtered x-ray diode diagnostic and the total power and energy diagnostic, gave 449 TW and 323 TW, respectively. Our analysis shows the latter to be the more accurate interpretation. More broadly, the comparison demonstrates the necessity to consider spectral response and field of view when inferring x-ray powers from z-pinch sources.

Pulsed-coil magnet systems for applying uniform 10-30 T fields to centimeter-scale targets on Sandia's Z facility.

Sandia has successfully integrated the capability to apply uniform, high magnetic fields (10-30 T) to high energy density experiments on the Z facility. This system uses an 8-mF, 15-kV capacitor bank to drive large-bore (5 cm diameter), high-inductance (1-3 mH) multi-turn, multi-layer electromagnets that slowly magnetize the conductive targets used on Z over several milliseconds (time to peak field of 2-7 ms). This system was commissioned in February 2013 and has been used successfully to magnetize more than 30 experiments up to 10 T that have produced exciting and surprising physics results. These experiments used split-magnet topologies to maintain diagnostic lines of sight to the target. We describe the design, integration, and operation of the pulsed coil system into the challenging and harsh environment of the Z Machine. We also describe our plans and designs for achieving fields up to 20 T with a reduced-gap split-magnet configuration, and up to 30 T with a solid magnet configuration in pursuit of the Magnetized Liner Inertial Fusion concept.

Update on the effects of a sierran wildfire on surface runoff water quality.

Wildfire has been shown to increase the short-term (1-3 yr) mobilization of mineral N and P in forest ecosystems of the Sierra Nevada Mountains and Lake Tahoe Basin. The ensuing effects on tributary and lake water quality are uncertain. The purpose of this investigation was to assess the impacts on runoff water quality over an intermediate time frame of 5 yr (2002-2007) after a wildfire event. Our design included fixed plots randomly placed within burned and unburned areas. Because each plot was sampled repeatedly during the study, we treated plots as repeated random effects in the analysis. We used a mixed model approach to analyze nutrient runoff concentrations and load for NH-N, NON and P in phosphate form (designated as ortho P or PO-P) where treatment (unburned vs. burned), time (pre-wildfire, post-wildfire year 1, year 2, etc.), and their interaction were fixed effects. Concentrations and loads of mineral N and P were higher in runoff from the burned areas immediately after wildfire. Because high water years may also contribute to higher runoff nutrient concentrations and loading, a wildfire followed by a high water year within the first season after a wildfire would likely have a much greater impact on runoff (and hence tributary) water quality than a wildfire followed by a low runoff water year.

Renal cell carcinoma: resistance to therapy, role of apoptosis, and the prognostic and therapeutic target potential of TRAF proteins.

Renal cell carcinoma (RCC) is the commonest of the renal neoplasms. Although surgery and cryoablation are successful curative treatments for localized RCC, most patients are diagnosed with advanced or metastatic RCC, which has a poor prognosis. RCC are a heterogeneous set of cancers that have traditionally been classified and staged using cellular characteristics, size, local extension and distant metastases. Current staging systems provide good prognostic information, but it is very likely that the identification of new more accurate and predictive prognostic markers, not currently included in traditional staging systems, will improve the outcome for RCC patients. For this reason, increased knowledge of the underlying molecular characteristics of RCC development and progression is necessary. In most cancers, but especially RCC, deregulated control of apoptosis contributes to cancer growth by aberrantly extending cell viability and facilitating resistance to cancer therapies. Here we present the hypothesis that select members of the tumor necrosis factor (TNF) superfamily, the TNF receptor-associated factors (TRAFs), have a role in RCC apoptosis and may have prognostic significance for RCC. Candidate biomarkers for RCC are few, and the TRAFs may be important inclusions in panels of biomarkers for RCC. TRAFs may also be potential molecular targets for new therapies, either through their ability to promote apoptosis in the cancers themselves, or through their ability to modulate the immune defence against cancer progression. Some support data are presented here for our hypothesis. However, these novel concepts need further careful analysis to allow clinicians and oncologists any assistance for earlier detection of RCC and for characterizing patients with RCC for individualised targeted therapy.

Sexual and lifetime selection on body size in a marine fish: the importance of life-history trade-offs.

Many field measurements of viability and sexual selection on body size indicate that large size is favoured. However, life-history theory predicts that body size may be optimized and that patterns of selection may often be stabilizing rather than directional. One reason for this discrepancy may be that field estimates of selection tend to focus on limited components of fitness and may not fully measure life-history trade-offs. We use an 8-year, demographic field study to examine both sexual selection and lifetime selection on body size of a coral reef fish (the bicolour damselfish, Stegastes partitus). Selection via reproductive success of adults was very strong (standardized selection differential=1.04). However, this effect was balanced by trade-offs between large adult size and reduced cumulative survival during the juvenile phase. When we measured lifetime fitness (net reproductive rate), selection was strongly stabilizing and only weakly directional, consistent with predictions from life-history theory.

Mercury distribution across 14 U.S. Forests. Part I: spatial patterns of concentrations in biomass, litter, and soils.

Results from a systematic investigation of mercury (Hg) concentrations across 14 forest sites in the United States show highest concentrations in litter layers, strongly enriched in Hg compared to aboveground tissues and indicative of substantial postdepositional sorption of Hg. Soil Hg concentrations were lower than in litter, with highest concentrations in surface soils. Aboveground tissues showed no detectable spatial patterns, likely due to 17 different tree species present across sites. Litter and soil Hg concentrations positively correlated with carbon (C), latitude, precipitation, and clay (in soil), which together explained up to 94% of concentration variability. We observed strong latitudinal increases in Hg in soils and litter, in contrast to inverse latitudinal gradients of atmospheric deposition measures. Soil and litter Hg concentrations were closely linked to C contents, consistent with well-known associations between organic matter and Hg, and we propose that C also shapes distribution of Hg in forests at continental scales. The consistent link between C and Hg distribution may reflect a long-term legacy whereby old, C-rich soil and litter layers sequester atmospheric Hg depositions over long time periods. Based on a multiregression model, we present a distribution map of Hg concentrations in surface soils of the United States.