Zoogeomorphological behaviours in fish and the potential impact of benthic feeding on bed material mobility in fluvial landscapes     

Stephen Rice  Andrew Pledger  Julia Toone  Kate Mathers 《地球表面变化过程与地形》2019,44(1):54-66

Foraging by benthivorous fish can affect bed material mobility and sediment flux. This paper collates evidence of benthic feeding effects at local scales and evaluates the possibility that large numbers of foraging fish, each of which accomplishes a small amount of geomorphic work when feeding, may have a cumulative effect across river systems. A first synthesis of research from several disciplines provides a deeper understanding of how fish disturb and condition bed materials with implications for sediment mobility. To evaluate the spatial extent of benthic feeding and therefore the potential for it to have a large-scale effect, the distribution of benthivorous fish is established across a large river network. After quality control, the dataset yields a comprehensive set of fish community information based on over 61 000 individuals and 30 species at 176 sites. The factors that are likely to mediate foraging and its geomorphological effectiveness are considered. A novel scoring system that incorporates three key controls (fish feeding behaviour, fish abundance and fish body size) is then applied across the river network to predict where geomorphologically effective benthic feeding is feasible and its possible relative magnitude. Our results demonstrate, for the first time, that the potential for zoogeomorphic impacts is widespread but variable in space as a function of community composition and the abundance of key benthivores. An initial calibration against measured field impacts suggests that benthic feeding may cause measurable geomorphological disturbance at more than 90% of sites in this large network. Together, previous work and this unique analysis suggest that benthic feeding is sufficiently effective and extensive to warrant additional research. Investigating the role of benthivorous fish in fluvial geomorphology is important because it may yield results that challenge the assumption that biota are irrelevant sources of energy in geomorphological systems. Key research questions and a roadmap to facilitate progress are identified. © 2018 John Wiley & Sons, Ltd.  相似文献   

Predicting site-specific storm wave run-up     

Fiedler  Julia W.  Young  Adam P.  Ludka  Bonnie C.  O’Reilly  William C.  Henderson  Cassandra  Merrifield  Mark A.  Guza  R. T. 《Natural Hazards》2020,104(1):493-517

Natural Hazards - Storm wave run-up causes beach erosion, wave overtopping, and street flooding. Extreme runup estimates may be improved, relative to predictions from general empirical formulae...  相似文献   

Balance of S in a constructed wetland built to treat acid mine drainage, Idaho Springs, Colorado, U.S.A.     

Steven D. Machemer  Julia S. Reynolds  Leslie S. Laudon  Thomas R. Wildeman 《Applied Geochemistry》1993,8(6)

The wetland constructed at the Big Five Tunnel in Idaho Springs, Colorado was designed to remove, passively, heavy metals from acid mine drainage. In optimizing the design of such a wetland, an improved understanding of the chemical processes operating there was required, particularly SO₄²⁻ reduction and sulfide precipitation. For this purpose, field and laboratory data were collected to study the balance of S in the system. Field data collected included water analyses of the mine drainage and wetland effluents and measurements of H₂S gas emissions from the wetland. The concentration of sulfide in the wetland effluent ranged from 10⁻⁴ to 10⁻³ mol/l. The average rates of H₂S emission from the surface of the substrate were 150 nmol/cm²/d in the summer and 0.17 and 0.35 nmol/cm²/d in the winter. This maximum estimated loss of sulfide was not significant in reducing the amount of sulfide available for precipitation with metals. Sequential extraction experiments for S on wetland substrates showed that acid volatile sulfides (AVS) increased with time in the wetland substrate. A serum bottle experiment was conducted to study the S balance in the Big Five wetland by quantitatively measuring the amount of S in different phases as microbial SO₄²⁻ reduction progressed. The increase in AVS reasonably balanced the decrease in SO₄²⁻ concentration in the experiment, suggesting that the decrease in SO₄²⁻ concentration represented the amount of SO₄²⁻ reduced and that nearly all of the sulfide produced was precipitated as AVS. Sulfide precipitation was determined to be the primary metal removal process in the wetland system and amorphous FeS is the primary iron sulfide formed in the substrate.  相似文献   

The Australian continental shelf: Has Australia's high-latitude diplomacy paid off?’     

Julia Jabour 《Marine Policy》2009

The Commission on the Limits of the Continental Shelf has granted Australia extended continental shelf areas around two of its sub-Antarctic island groups, and these extend into the Antarctic Treaty area. The overlap potentially raises conflict between Australian and Antarctic interests. Australia's submission included and expressly excluded Antarctic data and its high-latitude diplomacy paid off, but its next steps will be crucial to gaining acceptance by other Antarctic Treaty parties. It is likely that any resource exploitation will stop at the fence (60° South) during the life of the Treaty.  相似文献   

Holocene landscape reconstruction in the surroundings of the Temple of Pepi I at ancient Bubastis,southeastern Nile Delta (Egypt)     

Philipp Garbe  Amr Abd El-Raouf  Ashraf Es-Senussi  Eva Lange-Athinodorou  Julia Meister 《Geoarchaeology》2024,39(1):17-34

In ancient Egypt, lakes, canals, and other water bodies were an essential part of the sacred landscape in which temples were embedded. In recent years, geoarchaeological research at the site of the Temple of Bastet at Bubastis in the southeastern Nile Delta has proven the existence of two water canals surrounding the temple. It has now been investigated whether these canals were connected to the Temple of Pepi I (2300–2250 B.C.E.), located approximately 100 m to the west of the Temple of Bastet. To explore the Holocene landscape genesis of the Temple of Pepi I, 15 drillings and six geoelectrical profile lines were performed in the surroundings of the temple in spring 2022. The results show loamy to clayey sediments in deeper sections of all drillings with a maximum thickness of 1.70 m, indicating a marshy or swampy depositional environment. Based on the recovered sediment sequences and archaeological remains in the vicinity of the Temple of Pepi I, the marshy or swampy area existed before the Fourth Dynasty. During the Old Kingdom (ca. 2850–2180 B.C.E.), the former marshland either dried up through natural processes or was intentionally drained and filled with sediments for subsequent use for occupation. Regarding the original research question, there is as yet no evidence for a direct connection to the canals of the Temple of Bastet.  相似文献   

Modelling spatio-temporal soil moisture dynamics in mountain tundra     

Vilna Tyystjrvi  Julia Kemppinen  Miska Luoto  Tuula Aalto  Tiina Markkanen  Samuli Launiainen  Antti-Jussi Kieloaho  Juha Aalto 《水文研究》2022,36(1):e14450

Soil moisture has a fundamental influence on the processes and functions of tundra ecosystems. Yet, the local dynamics of soil moisture are often ignored, due to the lack of fine resolution, spatially extensive data. In this study, we modelled soil moisture with two mechanistic models, SpaFHy (a catchment-scale hydrological model) and JSBACH (a global land surface model), and examined the results in comparison with extensive growing-season field measurements over a mountain tundra area in northwestern Finland. Our results show that soil moisture varies considerably in the study area and this variation creates a mosaic of moisture conditions, ranging from dry ridges (growing season average 12 VWC%, Volumetric Water Content) to water-logged mires (65 VWC%). The models, particularly SpaFHy, simulated temporal soil moisture dynamics reasonably well in parts of the landscape, but both underestimated the range of variation spatially and temporally. Soil properties and topography were important drivers of spatial variation in soil moisture dynamics. By testing the applicability of two mechanistic models to predict fine-scale spatial and temporal variability in soil moisture, this study paves the way towards understanding the functioning of tundra ecosystems under climate change.  相似文献