Driven by surges in global gold prices and additional socio-economic factors, artisanal small-scale gold mining (ASGM) in the Global South is increasing and driving emissions of significant quantities of mercury (Hg) into the air and fresh-water. Hg can be toxic to animal and human populations and exacerbate the degradation of neotropical freshwater eco-systems. We examined drivers of Hg accumulation in fish that inhabit oxbow lakes of Peru's Madre de Dios, a region with high biodiversity value and increasing human populations that depend on ASGM. We hypothesized that fish Hg levels would be driven by local ASGM activities, by environmental Hg exposure, by water quality, and by fish tro-phic level. We sampled fish in 20 oxbow lakes spanning protected areas and areas subject to ASGM during the dry sea-son. Consistent with previous findings, Hg levels were positively associated with ASGM activities, and were higher in larger, carnivorous fish and where water had lower dissolved oxygen levels. In addition, we found a negative relation-ship between fish mercury levels associated with ASGM and the occurrence of the piscivorous giant otter. The link be-tween fine-scale quantification of spatial ASGM activity and Hg accumulation, as indicated by the result that in the lotic environment, localized effects of gold mining activities are stronger drivers (77 % model support) of Hg accumu-lation than environmental exposure (23 %) constitutes a novel contribution to a growing body of literature on Hg con-tamination. Our findings provide additional evidence of high Hg exposure risks to neotropical human and top carnivore populations subject to the impacts of ASGM, which depend on freshwater ecosystems undergoing gradual degradation. The documented spatial variation in Hg accumulation and increased Hg levels in carnivorous fish should serve as a warning to human communities in Madre de Dios to avoid the proximity of high-intensity gold mining areas and minimize local carnivorous fish consumption.

Mercury contamination from artisanal and small-scale gold mining (ASGM) currently accounts for 37% of the global total, often affecting tropical regions where regulations, if they exist, are often poorly enforced. Ingestion by people and other animals damages the nervous, reproductive, and cognitive systems. Despite the efforts of many organizations and governments to curb mercury releases from ASGM, it is increasing globally. There are many possible interventions, all with significant complexity and cost. Therefore, we recommend taking an established systematic approach to articulate the current situation and construct theories of change (ToC) for different possible interventions for any government or organization trying to solve this problem. Here we present a high-level situation analysis and generic ToC to support a more coordinated approach that explicitly builds upon previous experience to identify organization- and situation-appropriate engagement on this issue. We then illustrate the use of these generic models to construct a specific ToC with a policy-focused entry point. This includes interventions through (1) engagement with the global Minamata Convention on Mercury; (2) support for existing national laws and policies connected to ASGM and mercury contamination; and (3) engagement of indigenous people and local communities with governments to meet the governments' legal obligations. By methodically articulating assumptions about interventions, connections among actions, and desired outcomes, it is possible to create a more effective approach that will encourage more coordination and cooperation among governments and other practitioners to maximize their investments and support broad environmental and socio-political outcomes necessary to address this pernicious problem.

Artisanal and small-scale gold mining (ASGM) is the primary global source of anthropogenic mercury (Hg) emissions. It has impacted the Amazon rainforest in the Peruvian region of Madre de Dios. However, few studies have investigated Hg's distribution in terrestrial ecosystems in this region. We studied Hg's distribution and its predictors in soil and native plant species from artisanal mining sites. Total Hg concentrations were determined in soil samples collected at different depths (0-5cm and 5-30cm) and plant samples (roots, shoots, leaves) from 19 native plant species collected in different land cover categories: naked soil (L1), gravel piles (L2), natural regeneration (L3), reforestation (L4), and primary forest (L5) in the mining sites. Hg levels in air were also studied using passive air samplers. The highest Hg concentrations in soil (average 0.276 and 0.210mgkg-1 dw.) were found in the intact primary forest (L5) at 0-5cm depth and in the plant rooting zones at 5-30cm depth, respectively. Moreover, the highest Hg levels in plants (average 0.64mgkg-1 dw) were found in foliage of intact primary forest (L5). The results suggest that the forest in these sites receives Hg from the atmosphere through leaf deposition and that Hg accumulates in the soil surrounding the roots. The Hg levels found in the plant leaves of the primary forest are the highest ever recorded in this region, exceeding values found in forests impacted by Hg pollution worldwide and raising concerns about the extent of the ASGM impact in this ecosystem. Correlations between Hg concentrations in soil, bioaccumulation in plant roots, and soil physical-chemical characteristics were determined. Linear regression models showed that the soil organic matter content (SOM), pH, and electrical conductivity (EC) predict the Hg distribution and accumulation in soil and bioaccumulation in root plants.

Far-infrared astronomy has advanced rapidly since its inception in the late 1950s, driven by a maturing technology base and an expanding community of researchers. This advancement has shown that observations at far-infrared wavelengths are important in nearly all areas of astrophysics, from the search for habitable planets and the origin of life to the earliest stages of galaxy assembly in the first few hundred million years of cosmic history. The combination of a still-developing portfolio of technologies, particularly in the field of detectors, and a widening ensemble of platforms within which these technologies can be deployed, means that far-infrared astronomy holds the potential for paradigm-shifting advances over the next decade. We examine the current and future far-infrared observing platforms, including ground-based, suborbital, and space-based facilities, and discuss the technology development pathways that will enable and enhance these platforms to best address the challenges facing far-infrared astronomy in the 21st century. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License.

The NASA Stardust mission used silica aerogel slabs to slowly decelerate and capture impinging cosmic dust particles for return to Earth. During this process, impact tracks are generated along the trajectory of the particle into the aerogel. It is believed that the morphology and dimensions of these tracks, together with the state of captured grains at track termini, may be linked to the size, velocity, and density of the impacting cosmic dust grain. Here, we present the results of laboratory hypervelocity impact experiments, during which cosmic dust analog particles (diameters of between 0.2 and 0.4 mu m), composed of olivine, orthopyroxene, or an organic polymer, were accelerated onto Stardust flight-spare low-density (approximately 0.01 g cm(-3)) silica aerogel. The impact velocities (3-21 km s(-1)) were chosen to simulate the range of velocities expected during Stardust's interstellar dust (ISD) collection phases. Track lengths and widths, together with the success of particle capture, are analyzed as functions of impact velocity and particle composition, density, and size. Captured terminal particles from low-density organic projectiles become undetectable at lower velocities than those from similarly sized, denser mineral particles, which are still detectable (although substantially altered by the impact process) at 15 km s(-1). The survival of these terminal particles, together with the track dimensions obtained during low impact speed capture of small grains in the laboratory, indicates that two of the three best Stardust candidate extraterrestrial grains were actually captured at speeds much lower than predicted. Track length and diameters are, in general, more sensitive to impact velocities than previously expected, which makes tracks of particles with diameters of 0.4 mu m and below hard to identify at low capture speeds (<10 km s(-1)). Therefore, although captured intact, the majority of the interstellar dust grains returned to Earth by Stardust remain to be found.

Black hole mass measurements outside the local Universe are critically important to derive the growth of supermassive black holes over cosmic time, and to study the interplay between black hole growth and galaxy evolution. In this paper, we present two measurements of supermassive black hole masses from reverberation mapping (RM) of the broad C IV emission line. These measurements are based on multiyear photometry and spectroscopy from the Dark Energy Survey Supernova Program (DES-SN) and the Australian Dark Energy Survey (OzDES), which together constitute the OzDES RM Program. The observed reverberation lag between the DES continuum photometry and the OzDES emission line fluxes is measured to be 358(-123)(+126) and 343(-84)(+58) d for two quasars at redshifts of 1,905 and 2.593, respectively. The corresponding masses of the two supermassive black holes are 4.4 x 10(9) and 3.3 x 10(9) M-circle dot, which are among the highest redshift and highest mass black holes measured to date with RM studies. We use these new measurements to better determine the C IV radius luminosity relationship for high-luminosity quasars, which is fundamental to many quasar black hole mass estimates and demographic studies,

We present new Karl G. Jansky Very Large Array (VLA, 1.5 GHz) radio data for the giant elliptical galaxy IC 4296, supported by archival radio, X-ray (Chandra, and XMM-Newton) and optical (SOAR, and HST) observations. The galaxy hosts powerful radio jets piercing through the inner hot X-ray emitting atmosphere, depositing most of the energy into the ambient intracluster medium (ICM). Whereas the radio surface brightness of the A configuration image is consistent with a Fanaroff-Riley Class I system, the D configuration image shows two bright, relative to the central region, large (similar to 160 kpc diameter), well-defined lobes, previously reported by Killeen et al., at a projected distance r greater than or similar to 230 kpc. The XMM-Newton image reveals an X-ray cavity associated with one of the radio lobes. The total enthalpy of the radio lobes is similar to 7 x 10(59) erg and the mechanical power output of the jets is similar to 10(44) erg s(-1). The jets are mildly curved and possibly rebrightened by the relative motion of the galaxy and the ICM. The lobes display sharp edges, suggesting the presence of bow shocks, which would indicate that they are expanding supersonically. The central entropy and cooling time of the X-ray gas are unusually low and the nucleus hosts a warm H alpha + [N II] nebula and a cold molecular CO disc. Because most of the energy of the jets is deposited far from the nucleus, the atmosphere of the galaxy continues to cool, apparently feeding the central supermassive black hole and powering the jet activity.

We present a description of the Australian Dark Energy Survey (OzDES) and summarize the results from its 6 years of operations. Using the 2dF fibre positioner and AAOmega spectrograph on the 3.9-m Anglo-Australian Telescope, OzDES has monitored 771 active galactic nuclei, classified hundreds of supernovae, and obtained redshifts for thousands of galaxies that hosted a transient within the 10 deep fields of the Dark Energy Survey. We also present the second OzDES data release, containing the redshifts of almost 30 000 sources, some as faint as r(AB) = 24 mag, and 375 000 individual spectra. These data, in combination with the time-series photometry from the Dark Energy Survey, will be used to measure the expansion history of the Universe out to z similar to 1.2 and the masses of hundreds of black holes out to z similar to 4. OzDES is a template for future surveys that combine simultaneous monitoring of targets with wide-field imaging cameras and wide-field multi-object spectrographs.

Recent radio surveys have revealed pulsars with dispersion and scattering delays induced by ionized gas that are larger than the rest of the observed pulsar population, in some cases with electron column densities (or dispersion measures; DMs) larger than the maximum predictions of Galactic electron density models. By cross-matching the observed pulsar population against H II region catalogs, we show that the majority of pulsars with DM > 600 pc cm−3 and scattering delays τ (1 GHz) > 10 ms lie behind H II regions, and that H II region intersections may be relevant to as much as a third of the observed pulsar population. The fraction of the full pulsar population with sightlines intersecting H II regions is likely larger. Accounting for H II regions resolves apparent discrepancies where Galactic electron density models place high-DM pulsars beyond the Galactic disk. By comparing emission measures (EMs) inferred from recombination line observations to pulsar DMs, we show that H II regions can contribute tens to hundreds of pc cm−3 − 3 in electron column density along a pulsar LOS. We find that nearly all pulsars with significant excess (and deficit) scattering from the mean τ-DM relation are spatially coincident with known discrete ionized gas structures, including H II regions. Accounting for H II regions is critical to the interpretation of radio dispersion and scattering measurements as electron density tracers, both in the Milky Way and in other galaxies.

This study presents a comprehensive analysis of a two-patch, two-life stage SI model without recovery from infection, focusing on the dynamics of disease spread and host population viability in natural populations. The model, inspired by real-world ecological crises like the decline of amphibian populations due to chytridiomycosis and sea star populations due to Sea Star Wasting Disease, aims to understand the conditions under which a sink host population can present ecological rescue from a healthier, source population. Mathematical and numerical analyses reveal the critical roles of the basic reproductive numbers of the source and sink populations, the maturation rate, and the dispersal rate of juveniles in determining population outcomes. The study identifies basic reproduction numbers R 0 for each of the patches, and conditions for the basic reproduction numbers to produce a receiving patch under which its population. These findings provide insights into managing natural populations affected by disease, with implications for conservation strategies, such as the importance of maintaining reproductively viable refuge populations and considering the effects of dispersal and maturation rates on population recovery. The research underscores the complexity of host-pathogen dynamics in spatially structured environments and highlights the need for multi-faceted approaches to biodiversity conservation in the face of emerging diseases.