Mineralogical characterization of the thrusted manganese ore above the Blackridge Thrust Fault,Kalahari Manganese Field: The footprint of the Mukulu Enrichment

The thrusted manganese ore above the Blackridge Thrust Fault is a predominantly unstudied ore‐type and as such, there is an urgent need to petrographically characterize it. A total of 80 samples were collected from the thrusted lower manganese ore bed of six boreholes on Mukulu in the north of the Kalahari Manganese Field. Each sample underwent a range of optical and electron petrographic analyses in order to effectively characterize three dominant stages of alteration, namely Stages 1, 2 and 3. Similar to the hydrothermally‐altered Wessels‐type manganese ore, braunite II is the predominant mineral phase present during Stage 1 alteration, and alters to bixbyite with increasing proximity to normal faults at the onset of Stage 2 alteration. The final stage of alteration is exhibited by the development of hausmannite and jacobsite adjacent to the ferruginised zone at the normal fault plane. Apatite precipitation, in abundances previously undocumented in the Kalahari Manganese Field, is a hallmark feature of the newly identified Mukulu Enrichment. This supergene‐related enrichment process contributed to the significant abundance of arsenic‐bearing apatite in the ore, whilst residually enriching the ore‐hosted Fe and Mn oxides.     

Building resilience through interlocal relations: Case studies of polar bear and walrus management in the Bering Strait

Arctic coastal communities in the Bering Strait region of Alaska (USA) and Chukotka (Russia) share a close relationship with their natural environments that can be characterized as a social–ecological system. This system is complex, featuring changing ecosystem conditions, multiple jurisdictions, migratory animal populations, and several cultures. We argue that linkages between communities in both countries enhance the effectiveness of transborder polar bear and walrus conservation. We find that locally embedded bilateral institutions can provide effective management venues that persist despite slow or lacking processes of international law because they provide a better fit between rules for managing and the true system state.     

Shifts in the thermal niche of almond under climate change

Delineating geographic shifts in crop cultivation under future climate conditions provides information for land use and water management planning, and insights to meeting future demand. A suitability modeling approach was used to map the thermal niche of almond cultivation and phenological development across the Western United States (US) through the mid-21st century. The Central Valley of California remains thermally suitable for almond cultivation through the mid-21st century, and opportunities for expansion appear in the Willamette Valley of western Oregon, which is currently limited by insufficient heat accumulation. Modeled almond phenology shows a compression in reproductive development under future climate. By the mid-21st century, almond phenology in the Central Valley showed ~?2-week delay in chill accumulation and ~?1- and ~?2.5-week advance in the timing of bloom and harvest, respectively. Although other climatic and non-climatic restrictions to almond cultivation may exist, these results highlight opportunities for shifts in the geography of high-value cropping systems, which may influence growers’ long-term land use decisions, and shape regional water and agricultural industry discussions regarding climate change adaptation options.     

USGS46 Greenland Ice Core Water – A New Isotopic Reference Material for δ2H and δ18O Measurements of Water

Ice core from Greenland was melted, filtered, homogenised, loaded into glass ampoules, sealed, autoclaved to eliminate biological activity, and calibrated by dual‐inlet isotope‐ratio mass spectrometry. This isotopic reference material (RM), USGS46, is intended as one of two secondary isotopic reference waters for daily normalisation of stable hydrogen (δ²H) and stable oxygen (δ¹⁸O) isotopic analysis of water with a mass spectrometer or a laser absorption spectrometer. The measured δ²H and δ¹⁸O values of this reference water were ?235.8 ± 0.7‰ and ?29.80 ± 0.03‰, respectively, relative to VSMOW on scales normalised such that the δ²H and δ¹⁸O values of SLAP reference water are, respectively, ?428 and ?55.5‰. Each uncertainty is an estimated expanded uncertainty (U = 2u_c) about the reference value that provides an interval that has about a 95‐percent probability of encompassing the true value. This reference water is available in cases containing 144 glass ampoules that are filled with either 4 ml or 5 ml of water per ampoule.     

Evaluating spatiotemporal variation in water chemistry of the upper Colorado River using longitudinal profiling

Stream water chemistry is traditionally measured as variation over time at fixed sites, with sparse sites providing a crude understanding of spatial heterogeneity. An alternative Lagrangian reference frame measures changes with respect to both space and time as water travels through a network. Here, we collected sensor-based measurements of water chemistry at high spatial resolution along nearly 500 km of the Upper Colorado River. Our objective was to understand sources of spatiotemporal heterogeneity across different solutes and determine whether longitudinal change manifests as smooth gradients as suggested by the River Continuum Concept (RCC) or as abrupt changes as suggested by the Serial Discontinuity Concept (SDC). Our results demonstrate that Lagrangian sampling integrates spatiotemporal variation, and profiles reflect processes that vary in both space and time and over different scales. Over each day of sampling, water temperature (T) and dissolved oxygen (DO) varied strongly in response to diel solar cycles, with most of the variation driven by sampling time rather than sampling location. Equilibration of T and DO with the atmosphere limited small scale spatial heterogeneity, with variation at the entire profile scale driven by regional climate gradients. As such, T and DO profiles more closely approximated the smooth gradients of the RCC (though including temporal sampling artefacts). Conversely, variation in specific conductance and nitrate (NO₃-N) was largely driven by spatial patterns of lateral inflows such as tributaries and groundwater. This resulted in discrete shifts in the profiles at or downstream of discontinuities, appearing as the profiles expected with the SDC. The concatenation of spatiotemporal variation that produces observed Lagrangian profiles presents interpretive challenges but also augments our understanding of where, how, and critically why water chemistry changes in time and space as it moves through river networks.     

Exploring the application of topographic indices in urban areas as indicators of pluvial flooding locations

In urban areas, the presence of impervious surfaces limits natural drainage and routes water to stormwater infrastructure with finite capacity, making these areas especially prone to flooding. Though large floods are responsible for endangering lives and causing extensive damage, there is growing evidence that more frequent floods with shallow water depths, termed nuisance flooding, can have a high cumulative cost and many direct and indirect damages. To determine whether locations of nuisance flooding may be linked to topography, we took a parsimonious, spatially distributed approach to explore whether high topographic index values co-occur with citizen-reported nuisance flooding. We obtained nuisance flood reports from the municipal data service 311 for several watersheds in New York City and Baltimore, USA. Our analysis tested two topographic indices (TI)—topographic wetness index (TWI) and sink depth—both calculated from high-resolution (~1 m) digital elevation models. Generally, our findings suggest that not all but many locations of reported flooding tend to coincide with deep sinks or large TWI. However, nuisance flooding reports most commonly coincided with deep sinks and high TWI when using a maximum, instead of coincident, TI value extracted around each reported location of flooding, an approach we used due to the uncertainty in location accuracy of flooding reports. Overall, our results show promise for application of topographic indices, typically applied in more natural settings, as indicators of nuisance flooding areas in urbanized environments. Although limitations to this approach exist, the application of TIs and crowd-sourced reporting in tandem could provide a useful starting point for mapping flood-prone areas in many cities with technologically adept community members and ample geospatial data.     

Urban greening,property and more-than-human commoning

ABSTRACT

Urban greening is about bringing vegetation into cities in ways that produce flourishing urban ecologies whilst also making cities more liveable for human inhabitants. We focus here on greening that is done through the maintenance or establishment of gardens, parks, urban forests and informal spaces. We argue that in contexts with established property law systems, such as Australia, making urban ecologies through greening is shaped heavily by relations of property tied to land. This includes constraining the extent to which urban greening can contribute to socio-ecologically just cities. We suggest that progressing greening that is more attentive to the geographies and temporalities of more-than-human life requires us to trouble the hold of property over greening. To do this we explore the possibilities opened up by the lens of urban commons/commoning. We engage with the emerging concept of more-than-human commoning as a way of attuning urban greening to nonhuman agency and affordances. We also grapple with the risk of obscuring or concealing difference between humans in the way commoning makes room for more-than-humans, especially in the context of settler-colonialism. We conclude by calling for a more overt politics of urban greening that encompasses diverse human and more-than-human experiences of the city.     

Reproductive Ecology of Black Mangrove (<Emphasis Type="Italic">Avicennia germinans</Emphasis>) Along the Louisiana Coast: Propagule Production Cycles,Dispersal Limitations,and Establishment Elevations

Black mangrove (Avicennia germinans) reproduces by producing propagules through the process of cryptovivipary, which requires a significant energy investment. We conducted a series of field and greenhouse studies to track propagule production in years of high and low disturbances (i.e., hurricanes), the effects of time and salinity on propagule dispersal potential, and the relationship between hydrology and propagule establishment elevations. Trees tended to produce greater numbers of propagules in years after hurricanes, and individual trees alternated the amount of energy they invested in reproduction in consecutive years. In the greenhouse, propagule buoyancy was affected by salinity with propagules in 36 remaining buoyant for over 110 days and establishment success decreasing with dispersal period length. Finally, a field survey across five sites in southeastern Louisiana revealed that the 2009 cohort of propagules established at significantly lower elevations than mature trees occurred. These findings elucidate some salient features of black mangrove reproductive biology in the northern portion of its North American distribution.