Fingerprinting hydrological and biogeochemical drivers of freshwater quality     

Ann Louise Heathwaite  Magdalena Bieroza 《水文研究》2021,35(1):e13973

Understanding the interplay between hydrological flushing and biogeochemical cycling in streams is now possible owing to advances in high-frequency water quality measurements with in situ sensors. It is often assumed that storm events are periods when biogeochemical processes become suppressed and longitudinal transport of solutes and particulates dominates. However, high-frequency data show that diel cycles are a common feature of water quality time series and can be preserved during storm events, especially those of low-magnitude. In this study, we mine a high-frequency dataset and use two key hydrochemical indices, hysteresis and flushing index to evaluate the diversity of concentration-discharge relationships in third order agricultural stream. We show that mobilization patterns, inferred from the hysteresis index, change on a seasonal basis, with a predominance of rapid mobilization from surface and near stream sources during winter high-magnitude storm events and of delayed mobilization from subsurface sources during summer low-magnitude storm events. Using dynamic harmonic regression, we were able to separate concentration signals during storm events into hydrological flushing (using trend as a proxy) and biogeochemical cycling (using amplitude of a diel cycle as a proxy). We identified three groups of water quality parameters depending on their typical c-q response: flushing dominated parameters (phosphorus and sediments), mixed flushing and cycling parameters (nitrate nitrogen, specific conductivity and pH) and cycling dominated parameters (dissolved oxygen, redox potential and water temperature). Our results show that despite large storm to storm diversity in hydrochemical responses, storm event magnitude and timing have a critical role in controlling the type of mobilization, flushing and cycling behaviour of each water quality constituent. Hydrochemical indices can be used to fingerprint the effect of hydrological disturbance on freshwater quality and can be useful in determining the impacts of global change on stream ecology.  相似文献   

Knowledge gaps in our perceptual model of Great Britain's hydrology     

Thorsten Wagener  Simon J. Dadson  David M. Hannah  Gemma Coxon  Keith Beven  John P. Bloomfield  Wouter Buytaert  Hannah Cloke  Paul Bates  Joseph Holden  Louise Parry  Rob Lamb  Nick A. Chappell  Matthew Fry  Gareth Old 《水文研究》2021,35(7):e14288

There is a no lack of significant open questions in the field of hydrology. How will hydrological connectivity between freshwater bodies be altered by future human alterations to the hydrological cycle? Where does water go when it rains? Or what is the future space–time variability of flood and drought events? However, the answers to these questions will vary with location due to the specific and often poorly understood local boundary conditions and system properties that control the functional behaviour of a catchment or any other hydrologic control volume. We suggest that an open, shared and evolving perceptual model of a region's hydrology is critical to tailor our science questions, as it would be for any other study domain from the plot to the continental scale. In this opinion piece, we begin to discuss the elements of and point out some knowledge gaps in the perceptual model of the terrestrial water cycle of Great Britain. We discuss six major knowledge gaps and propose four key ways to reduce them. While the specific knowledge gaps in our perceptual model do not necessarily transfer to other places, we believe that the development of such perceptual models should be at the core of the debate for all hydrologic communities, and we encourage others to have a similar debate for their hydrologic domain.  相似文献   

Scientists' warning on extreme wildfire risks to water supply     

François-Nicolas Robinne  Dennis W. Hallema  Kevin D. Bladon  Mike D. Flannigan  Gabrielle Boisramé  Christian M. Bréthaut  Stefan H. Doerr  Giuliano Di Baldassarre  Louise A. Gallagher  Amanda K. Hohner  Stuart J. Khan  Alicia M. Kinoshita  Rua Mordecai  João Pedro Nunes  Petter Nyman  Cristina Santín  Gary Sheridan  Cathelijne R. Stoof  Matthew P. Thompson  James M. Waddington  Yu Wei 《水文研究》2021,35(5):e14086

2020 is the year of wildfire records. California experienced its three largest fires early in its fire season. The Pantanal, the largest wetland on the planet, burned over 20% of its surface. More than 18 million hectares of forest and bushland burned during the 2019–2020 fire season in Australia, killing 33 people, destroying nearly 2500 homes, and endangering many endemic species. The direct cost of damages is being counted in dozens of billion dollars, but the indirect costs on water-related ecosystem services and benefits could be equally expensive, with impacts lasting for decades. In Australia, the extreme precipitation (“200 mm day −1 in several location”) that interrupted the catastrophic wildfire season triggered a series of watershed effects from headwaters to areas downstream. The increased runoff and erosion from burned areas disrupted water supplies in several locations. These post-fire watershed hazards via source water contamination, flash floods, and mudslides can represent substantial, systemic long-term risks to drinking water production, aquatic life, and socio-economic activity. Scenarios similar to the recent event in Australia are now predicted to unfold in the Western USA. This is a new reality that societies will have to live with as uncharted fire activity, water crises, and widespread human footprint collide all-around of the world. Therefore, we advocate for a more proactive approach to wildfire-watershed risk governance in an effort to advance and protect water security. We also argue that there is no easy solution to reducing this risk and that investments in both green (i.e., natural) and grey (i.e., built) infrastructure will be necessary. Further, we propose strategies to combine modern data analytics with existing tools for use by water and land managers worldwide to leverage several decades worth of data and knowledge on post-fire hydrology.  相似文献   

3D representation of geochemical data, the corresponding alteration and associated REE mobility at the Ranger uranium deposit, Northern Territory, Australia   总被引：1，自引：0，他引：1  

Louise A. Fisher  James S. Cleverley  Mark Pownceby  Colin MacRae 《Mineralium Deposita》2013,48(8):947-966

Interrogation and 3D visualisation of multiple multi-element data sets collected at the Ranger 1 No. 3 uranium mine, in the Northern Territory of Australia, show a distinct and large-scale chemical zonation around the ore body. A central zone of Mg alteration, dominated by extensive clinochlore alteration, overprints a biotite–muscovite–K-feldspar assemblage which shows increasing loss of Na, Ba and Ca moving towards the ore body. Manipulation of pre-existing geochemical data and integration of new data collected from targeted ‘niche’ samples make it possible to recognise chemical architecture within the system and identify potential fluid conduits. New trace element and rare earth element (REE) data show strong fractionation associated with the zoned alteration around the deposit and with fault planes that intersect and bound the deposit. Within the most altered portion of the system, isocon analysis indicates addition of elements including Mg, S, Cu, Au and Ni and removal of elements including Ca, K, Ba and Na within a zone of damage associated with ore precipitation. In the more distal parts of the system, processes of alteration and replacement associated with the mineralising system can be recognised. REE element data show enrichment in HREE centred about a characteristic peak in Dy in the high-grade ore zone while LREEs are enriched in the outermost portions of the system. The patterns recognised in 3D in zoning of geochemical groups and contoured S, K and Mg abundance and the observed REE patterns suggest a fluid flow regime in which fluids were predominately migrating upwards during ore deposition within the core of the ore system.  相似文献   

Hydrogeology of northern Sierra de Chiapas,Mexico: a conceptual model based on a geochemical characterization of sulfide-rich karst brackish springs     

Laura Rosales Lagarde  Penelope J. Boston  Andrew R. Campbell  Louise D. Hose  Gary Axen  Kevin W. Stafford 《Hydrogeology Journal》2014,22(6):1447-1467

Conspicuous sulfide-rich karst springs flow from Cretaceous carbonates in northern Sierra de Chiapas, Mexico. This is a geologically complex, tropical karst area. The physical, geologic, hydrologic and chemical attributes of these springs were determined and integrated into a conceptual hydrogeologic model. A meteoric source and a recharge elevation below 1,500 m are estimated from the spring-water isotopic signature regardless of their chemical composition. Brackish spring water flows at a maximum depth of 2,000 m, as inferred from similar chemical attributes to the produced water from a nearby oil well. Oil reservoirs may be found at depths below 2,000 m. Three subsurface environments or aquifers are identified based on the B, Li⁺, K⁺ and SiO₂ concentrations, spring water temperatures, and CO₂ pressures. There is mixing between these aquifers. The aquifer designated Local is shallow and contains potable water vulnerable to pollution. The aquifer named Northern receives some brackish produced water. The composition of the Southern aquifer is influenced by halite dissolution enhanced at fault detachment surfaces. Epigenic speleogenesis is associated with the Local springs. In contrast, hypogenic speleogenesis is associated with the brackish sulfidic springs from the Northern and the Southern environments.  相似文献   

A framework to assess the vulnerability of California commercial sea urchin fishermen to the impact of MPAs under climate change     

Cheryl Chen  David López-Carr  Barbara Louise Endemaño Walker 《GeoJournal》2014,79(6):755-773

This paper describes the development of a Livelihood Vulnerability Index (LVI) that estimates the relative ability of California commercial sea urchin fishermen to cope with the change associated with proposed marine protected areas. A key goal in establishing marine protected areas is to maximize conservation benefits while minimizing the potential negative impacts to local fishing communities. However, current impact analyses largely assume a linear relationship between percent of fishing area or revenue lost with the magnitude of impact to fishermen. The LVI described in this paper aims to provide an additional dimension to impact analyses in which the adaptive capacity of individual fishermen is examined to estimate the differential abilities of fishermen to cope with the loss of fishing areas or revenue. This paper advances vulnerability assessments as it develops a novel framework for identifying and measuring drivers of vulnerability for understudied fishing populations whose livelihoods depend upon marine resources. This vulnerability assessment is intended to inform the design of marine protected areas by enabling researchers to incorporate the adaptive capacity of fishermen into socioeconomic impact analyses. The LVI was developed for the California commercial sea urchin fishery in the context of proposed marine protected area networks develop through the California Marine Life Protected Act planning process. As climate change advances there is an increasing need to identify vulnerable and resilient populations and ways to bolster adaptive capacity given the environmental and economic changes ahead.  相似文献   

Socio-cultural dimensions of climate change: charting the terrain     

James McCarthy  Chery Chen  David López-Carr  Barbara Louise Endemaño Walker 《GeoJournal》2014,79(6):665-675

We have reached a crucial turning point in debates around climate change. A well established scientific consensus regarding the physical causes, dynamics, and at least many likely implications of anthropogenic climate change has thus far failed to result in any substantial movement towards mitigation. For many, then, the most urgent questions regarding climate change are now socio-cultural ones, such as: how do people come to hold and act on certain beliefs regarding environmental conditions and processes; how do institutional forms and histories shape and constrain the views and options of various sorts of actors; and what are relationships among fossil fuels, climate change, and the historical geographies and future trajectories of capitalism? Far from being simpler than physical and life science questions, these social science questions introduce entirely new sorts of actors, dynamics, and methodological challenges into this already complex and dynamic domain. This special issue takes up these topics. In this essay, we chart some of the major contours of contemporary social science thinking regarding climate change and introduce the articles in the special issue. We begin by examining work, from political science and scholarship on the commons, that foregrounds questions of sovereignty, territoriality, and cooperation with respect to environmental governance. Then we examine work from neoclassical economics and radical political economy, which frame climate change in terms of externalities, or contradiction and crisis, respectively. Finally, we examine the rapidly proliferating work exploring how individuals think and feel about these issues, emphasizing concepts of risk, communication, and governmentality.  相似文献   

Eminescu impact structure: Insight into the transition from complex crater to peak-ring basin on Mercury     

Samuel C. Schon  James W. Head  David M.H. Baker  Carolyn M. Ernst  Louise M. Prockter  Scott L. Murchie  Sean C. Solomon 《Planetary and Space Science》2011,59(15):1949-1959

Peak-ring basins represent an impact-crater morphology that is transitional between complex craters with central peaks and large multi-ring basins. Therefore, they can provide insight into the scale dependence of the impact process. Here the transition with increasing crater diameter from complex craters to peak-ring basins on Mercury is assessed through a detailed analysis of Eminescu, a geologically recent and well-preserved peak-ring basin. Eminescu has a diameter (∼125 km) close to the minimum for such crater forms and is thus representative of the transition. Impact crater size-frequency distributions and faint rays indicate that Eminescu is Kuiperian in age, geologically younger than most other basins on Mercury. Geologic mapping of basin interior units indicates a distinction between smooth plains and peak-ring units. Our mapping and crater retention ages favor plains formation by impact melt rather than post-impact volcanism, but a volcanic origin for the plains cannot be excluded if the time interval between basin formation and volcanic emplacement was less than the uncertainty in relative ages. The high-albedo peak ring of Eminescu is composed of bright crater-floor deposits (BCFDs, a distinct crustal unit seen elsewhere on Mercury) exposed by the impact. We use our observations to assess predictions of peak-ring formation models. We interpret the characteristics of Eminescu as consistent with basin formation models in which a melt cavity forms during the impact formation of craters at the transition to peak ring morphologies. We suggest that the smooth plains were emplaced via impact melt expulsion from the central melt cavity during uplift of a peak ring composed of BCFD-type material. In this scenario the ringed cluster of peaks resulted from the early development of the melt cavity, which modified the central uplift zone.  相似文献   

California’s local health agencies and the state’s climate adaptation strategy     

Louise Bedsworth 《Climatic change》2012,111(1):119-133

A changing climate will exacerbate many of the problems currently faced by California’s public health institutions. The public health impacts of climate change include: an increase in extreme heat events and associated increases in heat-related morbidity and mortality, increases in the frequency and severity of air pollution episodes, shifts in the range and incidence of vector-borne diseases, increases in the severity of wildfire, increased risks of drought and flooding, and other extreme events. This article assesses the readiness of California’s public health institutions to cope with the changes that will accompany a changing climate and how they relate to strategies laid out in the state’s Climate Adaptation Strategy. County-level health offices are the front line actors to preserve public health in the face of numerous threats, including climate change. Survey results show that local health officers in California believe that climate change is a serious threat to public health, but feel that they lack the funding and resources to reduce this risk. Local health agencies also have a number of tools in place that will be helpful for preparing for a changing climate.  相似文献   

Particulate aluminium in boreal streams: Towards a better understanding of its sources and influence on dissolved aluminium speciation     

Neil Cory  Ishi Buffam  Hjalmar Laudon  Louise Bjrkvald  Carl-Magnus Mrth  Stephan Khler  Kevin Bishop 《Applied Geochemistry》2009,24(9):1677-1685

The adverse impacts of the inorganic labile monomeric Al (Al_i) fraction on aquatic organisms have meant that Al (Al_tot) determination and even speciation has become a routine part of environmental monitoring and assessment. However, if samples are not filtered prior to analysis then particulate Al (Al_tot(p)) could influence the determination of Al_tot, and therefore the determination of the more toxicologically important (Al_i), both when it is measured analytically or modelled from Al_tot. This paper shows that the Al/DOC ratio in unfiltered samples can identify the Al_tot(p) fraction, and thus improve the speciation of Al_i. These findings are based on data from a study in a 67 km² catchment in northern Sweden during the snowmelt-driven spring flood of two consecutive years. Filtered and unfiltered samples were studied to determine the spatial and temporal patterns in Al_tot(p). The concentrations of Al_tot(p) were greatest in larger downstream sites where significant silt deposits are located. The sites with no silt in their drainage area showed a mean difference between filtered (Al_tot(f)) and unfiltered (Al_tot(uf)) samples of 6%, while sites with silt deposits had a mean difference of 65%. The difference between filtered and unfiltered samples was greatest at peak flow. Spikes in Al_tot(p) did not behave consistently during fractionation with a cation exchange column, resulting in increases in either measured Al_i(f) or non-labile monomeric Al (Al_o(f)). Al_tot(p) spikes were associated with sharp increases in the Al:DOC ratio. The baseflow Al:DOC ratio could be used to model filtered Al_tot from DOC with a Spearman rho of 0.75.  相似文献