scholarly journals A method for reconstructing past lake water phosphorus concentrations using sediment geochemical records

2021 ◽  
Author(s):  
Madeleine Moyle ◽  
John F. Boyle
Keyword(s):  
Lake Water ◽  
Water Quality Monitoring ◽  
Specific Reference ◽  
Site Specific ◽  
Burial Rate ◽  
Steady State Model ◽  
Sediment Records ◽  
Current Water ◽  
Study Sites

AbstractAn existing steady state model of lake phosphorus (P) budgets has been adapted to allow reconstruction of long-term average historic lake water total phosphorus (TP) concentrations using lake sediment records of P burial. This model can be applied without site-specific parameterisation, thus potentially having universal application. In principle, it is applicable at any site where there is both a sediment P burial record and knowledge of the current water budget, although we advise caution applying it to problematic sediment records. Tested at six published case study sites, modelled lake water TP concentrations agree well with water-quality monitoring data, and limited testing finds good agreement with wholly independent diatom inferred lake water TP. Our findings, together with a review of the literature, suggest that well preserved lake sediments can usefully record a long-term average P burial rate from which the long-term mean lake water TP can be reliably estimated. These lake water TP reconstructions can provide meaningful site-specific reference values to support decision making in lake eutrophication management, including establishing targets for lake restoration.

scholarly journals Towards a history of Holocene P dynamics for the Northern Hemisphere using lake sediment geochemical records

2021 ◽  
Vol 18 (20) ◽  
pp. 5609-5638
Author(s):  
Madeleine Moyle ◽  
John F. Boyle ◽  
Richard C. Chiverrell
Keyword(s):  
Lake Sediment ◽  
Northern Hemisphere ◽  
Lake Water ◽  
Landscape Development ◽  
Development History ◽  
P Cycling ◽  
Sediment Records ◽  
History Of ◽  
P Supply

Abstract. Present-day lake water phosphorus (P) enrichment and accelerated P cycling are changes superimposed on a dynamic Holocene history of landscape development following glaciation, changes in climate, and long-term low-intensity human activity. Knowledge of the history of long-term P dynamics is essential for understanding present-day landscape P export and for managing both terrestrial and aquatic environments. This study is the first attempt to constrain the timing and magnitude of terrestrial changes in Holocene P dynamics across the Northern Hemisphere using lake sediment records. Here we reconstruct trajectories in terrestrial Holocene P dynamics for the Northern Hemisphere. We apply a simple process model to published lake sediment geochemical P records from 24 sites, producing records of landscape P yield and reconstructing lake water total phosphorus (TP) concentrations. Individual site trajectories of landscape P yield and lake water TP vary systematically, with differences attributable to local landscape development history. Three distinct traits are apparent. Mountain sites with minimal direct human impact show falling P supply and conform to conceptual models of natural soil development (Trait 1). Lowland sites where substantial (pre-)historic agriculture was present show progressively increasing P supply (Trait 2). Lowland sites may also show a rapid acceleration in P supply over the last few centuries, where high-intensity land use, including settlements and farming, is present (Trait 3). Where data availability permitted comparison, our reconstructed TP records agree well with monitored lake water TP data, and our sediment-inferred P yields are comparable to reported catchment export coefficients. Comparison with diatom-inferred TP reveals good agreement for recent records. Our reconstructions form the first systematic assessment of average terrestrial P export for the Northern Hemisphere over the Holocene and provide the empirical data needed for constraining long-term landscape P cycling models and values for terrestrial P export that could be used for ocean P cycling models. The long-term perspective provided by our sediment-inferred TP can be used to identify pre-disturbance baselines for lake water quality, information essential to target-driven lake management. We find the first detectable anthropogenic impacts on P cycling ca. 6000 BP, with more substantial impacts as early as 3000 BP. Consequently, to characterize pre-disturbance lake P conditions at Trait 2 and Trait 3 sites, it is necessary to consider time periods before the arrival of early farmers. Our use of trait classifications has a predictive power for sites without sediment records, allowing prediction of TP baselines and P trajectories based on regional landscape development history.

scholarly journals Towards a history of Holocene P dynamics for the northern hemisphere using lake sediment geochemical records

2021 ◽  
Author(s):  
Madeleine Moyle ◽  
John Francis Boyle ◽  
Richard Christopher Chiverrell
Keyword(s):  
Lake Sediment ◽  
Northern Hemisphere ◽  
Lake Water ◽  
Landscape Development ◽  
Development History ◽  
P Cycling ◽  
Sediment Records ◽  
History Of ◽  
P Supply

Abstract. Present day lake water phosphorus (P) enrichment and accelerated P cycling are changes superimposed on a dynamic Holocene history of landscape recovery from glaciation, changes in climate, and long-term low-intensity human activity. Knowledge of the history of long-term P dynamics is essential for understanding present-day landscape P export and for managing both terrestrial and aquatic environments. This study is the first attempt to constrain the timing and magnitude of terrestrial changes in Holocene P dynamics across the Northern Hemisphere using lake sediment records. Here we reconstruct trajectories in terrestrial Holocene P dynamics for the Northern Hemisphere. We apply a simple process model to published lake sediment geochemical P records from 24 sites, producing records of landscape P yield and reconstructing lake water total phosphorus (TP) concentrations. Individual site trajectories of landscape P yield and lake water TP vary systematically, with differences attributable to local landscape development history. Three distinct traits are apparent. Mountain sites with minimal direct human impact show falling P supply and conform to conceptual models of natural soil development (Trait 1). Lowland sites where substantial (pre-)historic agriculture was present show progressively increasing P supply (Trait 2). Lowland sites may also show a rapid acceleration in P supply over the last few centuries, where high intensity land use, including settlements and farming, are present (Trait 3). Where data availability permitted comparison, our reconstructed TP records agree well with both monitored lake water TP data and diatom inferred TP, and our sediment inferred P yields are comparable to reported catchment export coefficients. Our reconstructions form the first systematic assessment of average terrestrial P export for the Northern Hemisphere over the Holocene and provide the empirical data needed for constraining long-term landscape P cycling models and values for terrestrial P export that could be used for ocean P cycling models. The long-term perspective provided by our sediment-inferred TP can be used to identify pre-disturbance baselines for lake water quality, information essential to target-driven lake management. We find the first detectable anthropogenic impacts on P cycling ca. 6000 BP, with more substantial impacts as early as 3000 BP. Consequently, to characterise pre-disturbance lake P conditions at Trait 2 and Trait 3 sites it is necessary to consider time periods before the arrival of early farmers. Our use of trait classifications has a predictive power for sites without sediment records, allowing prediction of TP baselines and P trajectories based on regional landscape development history.

Nest cameras do not affect nest survival in a meadow-nesting shorebird

2020 ◽  
pp. 1-10
Author(s):  
VOLKER SALEWSKI ◽  
LUIS SCHMIDT
Keyword(s):  
Nest Survival ◽  
Bird Species ◽  
Conservation Strategies ◽  
Survival Models ◽  
Northern Germany ◽  
Term Study ◽  
Long Term Study ◽  
Limosa Limosa ◽  
Study Sites

Summary Identifying the fate of birds’ nests and the causes of breeding failure is often crucial for the development of conservation strategies for threatened species. However, collecting these data by repeatedly visiting nests might itself contribute to nest failure or bias. To solve this dilemma, automatic cameras have increasingly been used as a time-efficient means for nest monitoring. Here, we consider whether the use of cameras itself may influence hatching success of nests of the Black-tailed Godwit Limosa limosa at two long-term study sites in northern Germany. Annually between 2013 and 2019, cameras were used to monitor godwit nests. In 2014 and 2019, nests were randomly equipped with cameras or not, and nest survival checked independently of the cameras. Nest-survival models indicated that survival probabilities varied between years, sites and with time of the season, but were unaffected by the presence of cameras. Even though predation is the main cause of hatching failure in our study system, we conclude that predators did not learn to associate cameras with food either when the cameras were initially installed or after they had been used for several years. Cameras were thus an effective and non-deleterious tool to collect data for conservation in this case. As other bird species may react differently to cameras at their nests, and as other sets of predators may differ in their ability to associate cameras with food, the effect of cameras on breeding success should be carefully monitored when they are used in a new study system.

scholarly journals Long-term effectiveness of faecal immunochemical test screening for proximal and distal colorectal cancers

Gut ◽  
2021 ◽  
pp. gutjnl-2020-322545
Author(s):  
Han-Mo Chiu ◽  
Grace Hsiao-Hsuan Jen ◽  
Ying-Wei Wang ◽  
Jean Ching-Yuan Fann ◽  
Chen-Yang Hsu ◽  
...  
Keyword(s):  
Large Scale ◽  
Distal Colon ◽  
Population Based ◽  
Proximal Colon ◽  
Advanced Stage ◽  
Site Specific ◽  
Faecal Immunochemical Test ◽  
Immunochemical Test ◽  
Selection Factors

ObjectiveTo measure the effects of faecal immunochemical test (FIT) for colorectal cancer (CRC) screening on overall and site-specific long-term effectiveness of population-based organised service screening.DesignA prospective cohort study of Taiwanese nationwide biennial FIT screening was performed. A total of 5 417 699 eligible subjects were invited to attend screening from 2004 through 2009 and were followed up until 2014. We estimated the adjusted relative rates (aRRs) on the effectiveness of reducing advanced-stage CRC (stage II+) and CRC death by Bayesian Poisson regression models with the full adjustment for a cascade of self-selection factors (including the screening rate and the colonoscopy rate) and the completeness of colonoscopy together with demographic features.ResultsFIT screening (exposed vs unexposed) reduced the incidence of advanced-stage CRC (48.4 vs 75.7 per 100 000) and mortality (20.3 vs 41.3 per 100 000). Statistically significant reductions of both incidence of advanced-stage CRCs (aRR=0.66, 95% CI 0.63 to 0.70) and deaths from CRC (aRR=0.60, 95% CI 0.57 to 0.64) were noted. FIT screening was more effective in reducing distal advanced-stage CRCs (aRR=0.61, 95% CI 0.58 to 0.64) and CRC mortality (aRR=0.56, 95% CI 0.53 to 0.69) than proximal advanced CRCs (aRR=0.84, 95% CI 0.77 to 0.92) and CRC mortality (aRR=0.72, 95% CI 0.66 to 0.80).ConclusionA large-scale population-based biennial FIT screening demonstrates 34% significant reduction of advanced-stage CRCs and 40% reduction of death from CRC with larger long-term effectiveness in the distal colon than the proximal colon. Our findings provide a strong and consistent evidence-based policy for supporting a sustainable population-based FIT organised service screening worldwide. The disparity of site-specific long-term effectiveness also provides an insight into the remedy for lower effectiveness of FIT screening in the proximal colon.

scholarly journals Territorial governance of managed retreat in Sweden: addressing challenges

2021 ◽  
Author(s):  
Gunnel Göransson ◽  
Lisa Van Well ◽  
David Bendz ◽  
Per Danielsson ◽  
Jim Hedfors
Keyword(s):  
Climate Adaptation ◽  
Governance Framework ◽  
Case Study Site ◽  
Feasible Option ◽  
Flexible Planning ◽  
Barriers And Opportunities ◽  
Study Sites ◽  
Inland Flooding

AbstractMany climate adaptation options currently being discussed in Sweden to meet the challenge of surging seas and inland flooding advocate holding the line through various hard and soft measures to stabilize the shoreline, while managed retreat is neither considered as feasible option nor has it been explicitly researched in Sweden. However, failure to consider future flooding from climate change in municipal planning may have dangerous and costly consequences when the water does come. We suggest that managed retreat practices are challenging in Sweden, not only due to public opinions but also because of a deficit of uptake of territorial knowledge by decision-makers and difficulties in realizing flexible planning options of the shoreline. A territorial governance framework was used as a heuristic to explore the challenges to managed retreat in four urban case studies (three municipalities and one county) representing different territorial, hydrological and oceanographic environments. This was done through a series of participatory stakeholder workshops. The analysis using a territorial governance framework based on dimensions of coordination, integration, mobilization, adaptation and realization presents variations in how managed retreat barriers and opportunities are perceived among case study sites, mainly due to the differing territorial or place-based challenges. The results also indicate common challenges regardless of the case study site, including coordination challenges and unclear responsibility, the need for integrated means of addressing goal conflicts and being able to adapt flexibly to existing regulations and plans. Yet rethinking how managed retreat could boost community resilience and help to implement long-term visions was seen as a way to deal with some of the territorial challenges.

scholarly journals A method for simulating risk profiles of wheat yield in data-sparse conditions

2021 ◽  
pp. 1-12
Author(s):  
G. Bracho-Mujica ◽  
P.T. Hayman ◽  
V.O. Sadras ◽  
B. Ostendorf
Keyword(s):  
Reference Site ◽  
Climate Impacts ◽  
Weather Data ◽  
Climate Data ◽  
High Quality ◽  
Risk Profiles ◽  
Record Length ◽  
Daily Weather Data ◽  
Study Sites

Abstract Process-based crop models are a robust approach to assess climate impacts on crop productivity and long-term viability of cropping systems. However, these models require high-quality climate data that cannot always be met. To overcome this issue, the current research tested a simple method for scaling daily data and extrapolating long-term risk profiles of modelled crop yields. An extreme situation was tested, in which high-quality weather data was only available at one single location (reference site: Snowtown, South Australia, 33.78°S, 138.21°E), and limited weather data was available for 49 study sites within the Australian grain belt (spanning from 26.67 to 38.02°S of latitude, and 115.44 to 151.85°E of longitude). Daily weather data were perturbed with a delta factor calculated as the difference between averaged climate data from the reference site and the study sites. Risk profiles were built using a step-wise combination of adjustments from the most simple (adjusted series of precipitation only) to the most detailed (adjusted series of precipitation, temperatures and solar radiation), and a variable record length (from 10 to 100 years). The simplest adjustment and shortest record length produced bias of modelled yield grain risk profiles between −10 and 10% in 41% of the sites, which increased to 86% of the study sites with the most detailed adjustment and longest record (100 years). Results indicate that the quality of the extrapolation of risk profiles was more sensitive to the number of adjustments applied rather than the record length per se.

scholarly journals Worldwide variations in artificial skyglow

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Christopher C. M. Kyba ◽  
Kai Pong Tong ◽  
Jonathan Bennie ◽  
Ignacio Birriel ◽  
Jennifer J. Birriel ◽  
...  
Keyword(s):  
Monitoring Program ◽  
Artificial Light ◽  
Clear Sky ◽  
International Monitoring ◽  
Sky Brightness ◽  
Ground Truthing ◽  
Study Sites ◽  
Night Sky Brightness ◽  
Key Questions

Abstract Despite constituting a widespread and significant environmental change, understanding of artificial nighttime skyglow is extremely limited. Until now, published monitoring studies have been local or regional in scope and typically of short duration. In this first major international compilation of monitoring data we answer several key questions about skyglow properties. Skyglow is observed to vary over four orders of magnitude, a range hundreds of times larger than was the case before artificial light. Nearly all of the study sites were polluted by artificial light. A non-linear relationship is observed between the sky brightness on clear and overcast nights, with a change in behavior near the rural to urban landuse transition. Overcast skies ranged from a third darker to almost 18 times brighter than clear. Clear sky radiances estimated by the World Atlas of Artificial Night Sky Brightness were found to be overestimated by ~25%; our dataset will play an important role in the calibration and ground truthing of future skyglow models. Most of the brightly lit sites darkened as the night progressed, typically by ~5% per hour. The great variation in skyglow radiance observed from site-to-site and with changing meteorological conditions underlines the need for a long-term international monitoring program.

Testing Long-Term Predictions from Hydro-Geochemical Models

1993 ◽  
Vol 333 ◽  
Author(s):  
William E. Glassley ◽  
Carol J. Bruton ◽  
William L. Bourcier
Keyword(s):  
Yucca Mountain ◽  
Taupo Volcanic Zone ◽  
Ambient Conditions ◽  
Volcanic Zone ◽  
Site Specific ◽  
Thermally Induced ◽  
Induced Flow ◽  
Geochemical Models ◽  
Kinetics And Thermodynamic

ABSTRACTThermally induced flow of liquid water and water vapor at the potential repository site at Yucca Mountain, Nevada, will extend hundreds of meters away from the repository edge. The resultant transfer of heat and mass will sufficiently perturb the ambient conditions such that a variety of mineralogical and chemical reactions will occur that may modify hydrological properties. The consequences of this “coupling” of geochemical and hydrological processes will vary through time, and will occur to different degrees in four regimes (T < Tboiling; T = Tboiling; T > T boiling; cooling) that will develop within the repository block. The dominant processes in the regimes differ, and reflect the local balance between: 1) kinetics and equilibrium; 2) dissolution and precipitation; 3) evaporation and boiling; and 4) fluid flow in matrix and fractures. Simulations were conducted of the evolution of these regimes, using laboratory derived kinetics and thermodynamic data, and site specific mineralogical and hydrological properties. These simulations identify regions where chemical and mineralogical equilibrium is likely to be achieved, and where net changes in hydrological properties will be concentrated. Tests of the results of these simulations have been initiated using field data from the Taupo Volcanic Zone, New Zealand. A preliminary series of calculations suggest that relative changes in porosity of as much as ± 20% to 30% may be possible for rocks with an initial porosity of 10%.

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