A New Sampler for the Collection and Retrieval of Dry Dust Deposition

Atmospheric dust can influence biogeochemical cycles, accelerate snowmelt, and affect air, water quality, and human health. Yet, the bulk of atmospherically transported material remains poorly quantified in terms of total mass fluxes and composition. This lack of information stems in part from the challenges associated with measuring dust deposition. Here we report on the design and efficacy of a new dry deposition sampler (Dry Deposition Sampling Unit (DSU)) and method that quantifies the gravitational flux of dust particles. The sampler can be used alone or within existing networks such as those employed by the National Atmospheric Deposition Program (NADP). Because the samplers are deployed sterile and the use of water to remove trapped dust is not required, this method allows for the recovery of unaltered dry material suitable for subsequent chemical and microbiological analyses. The samplers were tested in the laboratory and at 15 field sites in the western United States. With respect to material retention, sampler performance far exceeded commonly used methods. Retrieval efficiency was \u3e97% in all trials and the sampler effectively preserved grain size distributions during wind exposure experiments. Field tests indicated favorable comparisons to dust-on-snow measurement across sites (r2 0.70, p \u3c 0.05) and within sites to co-located aerosol data (r2 0.57–0.99, p \u3c 0.05). The inclusion of dust deposition and composition monitoring into existing networks increases spatial and temporal understanding of the atmospheric transport on materials and substantively furthers knowledge of the effects of dust on terrestrial ecosystems and human exposure to dust and associated deleterious compounds

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Deflation Patch Characteristics

Landscape position data for soil deflation landforms in West Greenland. Field measurements include scarp length, scarp height, and patch size. Elevation, aspect, slope, and distance to the Greenland Ice Sheet were calculated with imagery acquired from the Polar Geospatial Center. We calculated the patch expansion rate using the lichenometry dataset also available in this data package

Data from: Rates and processes of aeolian soil erosion in West Greenland

In arid landscapes across the globe, aeolian processes are key drivers of landscape change, but arid Arctic regions are often overlooked. In the Kangerlussuaq region of West Greenland, strong katabatic winds have removed discrete patches of soil and vegetation, exposing unproductive glacial till and bedrock. Although lake-sediment records suggest that landscape destabilization began approximately 1000 years ago, the upland soil erosion has never been directly dated. We use a novel application of lichenometry to estimate the rates and timing of soil erosion. We show that the formation of deflation patches occurred approximately 800–230 years ago, in general agreement with lake-sediment records. In West Greenland, the ‘Little Ice Age’ (AD 1350–1880) was characterized by a cold and arid climate, conditions that increased susceptibility to erosion. On average, deflation patches are expanding at a rate of 2.5 cm yr−1, and variation in the rate of patch expansion cannot be explained by proximity to the Greenland Ice Sheet (GrIS), slope, aspect, elevation, or patch size. An erosional threshold exists in this aeolian system, with climate conditions necessary for patch formation likely harsher than those necessary for continued patch expansion, a result that has implications for land management in arid regions. Currently, deflation patches are expanding throughout the study region and are forming in areas close to the GrIS, but future deflation rates are dependent on projected climate and potential land-use changes. Our results stress the importance of aeolian processes in arid polar landscapes such as Kangerlussuaq, and demonstrate the use of aeolian landforms in paleoclimate reconstructions and predicting future landscape change

Lichen Diameters

Raw Rhizocarpon sp. lichen diameters from soil deflation patches in West Greenland. We measured all yellow-green Rhizocarpon sp. without identifying to the species level. Lichen diameter measurements were collected along transects perpendicular to the active margin of the erosional landform. We measured the long axis of the lichens using digital calipers

Quantifying rates of soil deflation with Structure-from-Motion photogrammetry in west Greenland

Aeolian processes are important drivers of geomorphic change in cold regions. Because these processes often occur at slow timescales over large areas, it can be difficult to quantify rates using traditional field methods. In the Kangerlussuaq region of Greenland, strong katabatic winds have shaped distinct erosional landforms, or deflation patches, that appear to expand across the landscape. The modern erosion rate along the active margins, or scarps, of these deflation patches is unknown. We use Structure-from-Motion (SfM) photogrammetry to quantify the geomorphic change of ten deflation patches between 2014 and 2016. During the two-year study period, significant positive and negative change occurred at all sites, suggesting that deflation patches are active landforms and that geomorphic change is highly heterogeneous and localized. We observed significant change primarily along the scarps, while little to no change occurred in the center of the patches. Along the scarps, the mean negative change ranged from −0.7 to −2.5 cm, and erosion dominated in eight out of the ten deflation patches. The modern erosion rate appears to be lower than the century-scale rate of 2.5 cm yr−1 estimated from prior work using lichenometry, potentially because of the episodic nature of scarp retreat. Longer-term monitoring using these methods will help quantify the geomorphic response of this landscape to a rapidly changing regional climate

Back Trajectories for "Atmospheric Dust Deposition Varies by Season and Elevation in the Colorado Front Range, USA"

Back trajectory runs to accompany analysis of dust at sites near Boulder, CO, USA using the Stochastic Time-Inverted Lagrangian Trajectory model (STILT) run with High Resolution Rapid Refresh reanalysis data. This analysis was performed on the University of Utah's High Performance Computer 'lonepeak'. This modeling data may be used with scripts available at https://github.com/putmanannie/FrontRange-Dust; to produce the figures presented in the manuscript and supplemental information