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1. Influence of infrastructure on water quality and greenhouse gas dynamics in urban streams

   https://doi.org/10.5194/bg-14-2831-2017  

   Smith, Rose M. ; Kaushal, Sujay S. ; Beaulieu, Jake J. ; Pennino, Michael J. ; Welty, Claire ( January 2017 , Biogeosciences)

   Streams and rivers are significant sources of nitrous oxide (N₂O), carbon dioxide (CO₂), and methane (CH₄) globally, and watershed management can alter greenhouse gas (GHG) emissions from streams. We hypothesized that urban infrastructure significantly alters downstream water quality and contributes to variability in GHG saturation and emissions. We measured gas saturation and estimated emission rates in headwaters of two urban stream networks (Red Run and Dead Run) of the Baltimore Ecosystem Study Long-Term Ecological Research project. We identified four combinations of stormwater and sanitary infrastructure present in these watersheds, including: (1) stream burial, (2) inline stormwater wetlands, (3) riparian/floodplain preservation, and (4) septic systems. We selected two first-order catchments in each of these categories and measured GHG concentrations, emissions, and dissolved inorganic and organic carbon (DIC and DOC) and nutrient concentrations biweekly for 1 year. From a water quality perspective, the DOC : NO₃⁻ ratio of streamwater was significantly different across infrastructure categories. Multiple linear regressions including DOC : NO₃⁻ and other variables (dissolved oxygen, DO; total dissolved nitrogen, TDN; and temperature) explained much of the statistical variation in nitrous oxide (N₂O, r² =  0.78), carbon dioxide (CO₂, r² =  0.78), and methane (CH₄, r² =  0.50) saturation in stream water. We measured N₂O saturation ratios, which were among the highest reported in the literaturemore »for streams, ranging from 1.1 to 47 across all sites and dates. N₂O saturation ratios were highest in streams draining watersheds with septic systems and strongly correlated with TDN. The CO₂ saturation ratio was highly correlated with the N₂O saturation ratio across all sites and dates, and the CO₂ saturation ratio ranged from 1.1 to 73. CH₄ was always supersaturated, with saturation ratios ranging from 3.0 to 2157. Longitudinal surveys extending form headwaters to third-order outlets of Red Run and Dead Run took place in spring and fall. Linear regressions of these data yielded significant negative relationships between each gas with increasing watershed size as well as consistent relationships between solutes (TDN or DOC, and DOC : TDN ratio) and gas saturation. Despite a decline in gas saturation between the headwaters and stream outlet, streams remained saturated with GHGs throughout the drainage network, suggesting that urban streams are continuous sources of CO₂, CH₄, and N₂O. Our results suggest that infrastructure decisions can have significant effects on downstream water quality and greenhouse gases, and watershed management strategies may need to consider coupled impacts on urban water and air quality.« less
2. The Helium and Carbon Isotope Characteristics of the Andean Convergent Margin

   https://doi.org/10.3389/feart.2022.897267  

   Barry, P. H. ; De Moor, J. M. ; Chiodi, A. ; Aguilera, F. ; Hudak, M. R. ; Bekaert, D. V. ; Turner, S. J. ; Curtice, J. ; Seltzer, A. M. ; Jessen, G. L. ; et al ( June 2022 , Frontiers in Earth Science)

   Subduction zones represent the interface between Earth’s interior (crust and mantle) and exterior (atmosphere and oceans), where carbon and other volatile elements are actively cycled between Earth reservoirs by plate tectonics. Helium is a sensitive tracer of volatile sources and can be used to deconvolute mantle and crustal sources in arcs; however it is not thought to be recycled into the mantle by subduction processes. In contrast, carbon is readily recycled, mostly in the form of carbon-rich sediments, and can thus be used to understand volatile delivery via subduction. Further, carbon is chemically-reactive and isotope fractionation can be used to determine the main processes controlling volatile movements within arc systems. Here, we report helium isotope and abundance data for 42 deeply-sourced fluid and gas samples from the Central Volcanic Zone (CVZ) and Southern Volcanic Zone (SVZ) of the Andean Convergent Margin (ACM). Data are used to assess the influence of subduction parameters (e.g., crustal thickness, subduction inputs, and convergence rate) on the composition of volatiles in surface volcanic fluid and gas emissions. He isotopes from the CVZ backarc range from 0.1 to 2.6 R A ( n = 23), with the highest values in the Puna and the lowest inmore »the Sub-Andean foreland fold-and-thrust belt. Atmosphere-corrected He isotopes from the SVZ range from 0.7 to 5.0 R A ( n = 19). Taken together, these data reveal a clear southeastward increase in 3 He/ 4 He, with the highest values (in the SVZ) falling below the nominal range associated with pure upper mantle helium (8 ± 1 R A ), approaching the mean He isotope value for arc gases of (5.4 ± 1.9 R A ). Notably, the lowest values are found in the CVZ, suggesting more significant crustal inputs (i.e., assimilation of 4 He) to the helium budget. The crustal thickness in the CVZ (up to 70 km) is significantly larger than in the SVZ, where it is just ∼40 km. We suggest that crustal thickness exerts a primary control on the extent of fluid-crust interaction, as helium and other volatiles rise through the upper plate in the ACM. We also report carbon isotopes from ( n = 11) sites in the CVZ, where δ 13 C varies between −15.3‰ and −1.2‰ [vs. Vienna Pee Dee Belemnite (VPDB)] and CO 2 / 3 He values that vary by over two orders of magnitude (6.9 × 10 8 –1.7 × 10 11 ). In the SVZ, carbon isotope ratios are also reported from ( n = 13) sites and vary between −17.2‰ and −4.1‰. CO 2 / 3 He values vary by over four orders of magnitude (4.7 × 10 7 –1.7 × 10 12 ). Low δ 13 C and CO 2 / 3 He values are consistent with CO 2 removal (e.g., calcite precipitation and gas dissolution) in shallow hydrothermal systems. Carbon isotope fractionation modeling suggests that calcite precipitation occurs at temperatures coincident with the upper temperature limit for life (122°C), suggesting that biology may play a role in C-He systematics of arc-related volcanic fluid and gas emissions.« less
3. UAV-based Geotechnical Modeling and Mapping of an Inaccessible Underground Site

   Russell, E.A. ; MacLaughlin, M.M. ; Turner, R.M. ( June 2018 , UAV-based Geotechnical Modeling and Mapping of an Inaccessible Underground Site)

   Photogrammetry is becoming a more common method for mapping geological and structural features in underground mines. The issue of capturing geological and structural data in inaccessible areas of mines, such as those that are unsupported, remains even when utilizing photogrammetric methods; thus, geological models of mines are left with incomplete datasets. The implementation of Unmanned Aerial Vehicles (UAVs) underground has allowed for experimentation with photogrammetry conducted from a UAV platform. This paper contains the results of an investigation focused on collecting UAV-based imagery at underground locations within Barrick Gold Corporation’s Golden Sunlight Mine in Whitehall, Montana, and the use of the imagery to produce 3D models for mapping geologic features. The primary components of the study described are the underground imagery acquisition experiences and a comparison of underground photogrammetry modeling with UAV imagery using two sets of software: a) ADAM Technology’s 3DM CalibCam and 3DM Analyst and b) Bentley’s ContextCapture for 3D modeling combined with Split Engineering’s Split-FX for mapping. The lessons learned during this study may help guide future efforts using UAVs for capturing geologic data, as well as to help monitor stability in areas that are inaccessible.
4. Mapping Potentially Acid Generating Material on Abandoned Mine Lands Using Remotely Piloted Aerial Systems

   https://doi.org/10.3390/min11040365  

   Cramer, Alison S. ; Calvin, Wendy M. ; McCoy, Scott W. ; Breitmeyer, Ronald J. ; Haagsma, Marja ; Kratt, Christopher ( April 2021 , Minerals)

   Weathering and transport of potentially acid generating material (PAGM) at abandoned mines can degrade downstream environments and contaminate water resources. Monitoring the thousands of abandoned mine lands (AMLs) for exposed PAGM using field surveys is time intensive. Here, we explore the use of Remotely Piloted Aerial Systems (RPASs) as a complementary remote sensing platform to map the spatial and temporal changes of PAGM across a mine waste rock pile on an AML. We focus on testing the ability of established supervised and unsupervised classification algorithms to map PAGM on imagery with very high spatial resolution, but low spectral sampling. At the Perry Canyon, NV, USA AML, we carried out six flights over a 29-month period, using a RPAS equipped with a 5-band multispectral sensor measuring in the visible to near infrared (400–1000 nm). We built six different 3 cm resolution orthorectified reflectance maps, and our tests using supervised and unsupervised classifications revealed benefits to each approach. Supervised classification schemes allowed accurate mapping of classes that lacked published spectral libraries, such as acid mine drainage (AMD) and efflorescent mineral salts (EMS). The unsupervised method produced similar maps of PAGM, as compared to supervised schemes, but with little user input. Our classifiedmore »multi-temporal maps, validated with multiple field and lab-based methods, revealed persistent and slowly growing ‘hotspots’ of jarosite on the mine waste rock pile, whereas EMS exhibit more rapid fluctuations in extent. The mapping methods we detail for a RPAS carrying a broadband multispectral sensor can be applied extensively to AMLs. Our methods show promise to increase the spatial and temporal coverage of accurate maps critical for environmental monitoring and reclamation efforts over AMLs.« less
5. AiRobSim: Simulating a Multisensor Aerial Robot for Urban Search and Rescue Operation and Training

   https://doi.org/10.3390/s20185223  

   Chen, Junjie ; Li, Shuai ; Liu, Donghai ; Li, Xueping ( September 2020 , Sensors)

   Unmanned aerial vehicles (UAVs), equipped with a variety of sensors, are being used to provide actionable information to augment first responders’ situational awareness in disaster areas for urban search and rescue (SaR) operations. However, existing aerial robots are unable to sense the occluded spaces in collapsed structures, and voids buried in disaster rubble that may contain victims. In this study, we developed a framework, AiRobSim, to simulate an aerial robot to acquire both aboveground and underground information for post-disaster SaR. The integration of UAV, ground-penetrating radar (GPR), and other sensors, such as global navigation satellite system (GNSS), inertial measurement unit (IMU), and cameras, enables the aerial robot to provide a holistic view of the complex urban disaster areas. The robot-collected data can help locate critical spaces under the rubble to save trapped victims. The simulation framework can serve as a virtual training platform for novice users to control and operate the robot before actual deployment. Data streams provided by the platform, which include maneuver commands, robot states and environmental information, have potential to facilitate the understanding of the decision-making process in urban SaR and the training of future intelligent SaR robots.