scholarly journals Injection-Triggered Occlusion of Flow Pathways in Geothermal Operations

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Maren Brehme ◽  
Simona Regenspurg ◽  
Peter Leary ◽  
Fatih Bulut ◽  
Harald Milsch ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Statistical Interpretation ◽  
Biological Processes ◽  
Spatially Correlated ◽  
Flow Pathways ◽  
Study Sites ◽  
Physical Boundary ◽  
Geothermal Aquifer ◽  
Operational Data

Reasons for injectivity decline were investigated in a low-enthalpy geothermal aquifer in Klaipeda (Lithuania). It is one of the study sites within the DESTRESS project, which demonstrates different stimulation techniques in geothermal reservoirs. Due to low injectivity, production rates from the Lithuanian field are currently reduced, which lead to negative commercial implications for the site. Productivity from the same wells is measured to be 40 times higher. Injectivity decline in aquifers is often related to clogging processes in spatially correlated highly permeable structures, which control the main flow volume. We subdivided clogging processes into (1) physical, (2) chemical, and (3) biological processes and studied them by analyzing fluid and solid samples as well as operational data. The methods we used are fluid and solid analyses in situ, in the laboratory and in experimental setups, statistical interpretation, and numerical modeling. Our results show that the spatially correlating nature of permeable structures is responsible for exponentially decreasing injectivity because few highly permeable zones clog rapidly by intruded particles. In particular, field operations cause changes of the physical, chemical, and biological processes in the aquifer. Mineral precipitation and corrosion are the main chemical processes observed at our site. Microbial activity causes biofilm while fines migration is caused by changes in physical boundary conditions. Moreover, these processes can affect each other and generate further reactions, for example, microbial activity triggers corrosion in surface pipelines.

scholarly journals Nutrient Dynamics at the Sediment-Water Interface: Influence of Wastewater Effluents

2021 ◽  
Author(s):  
Meng Zhang ◽  
Robert A. Francis ◽  
Michael A. Chadwick
Keyword(s):  
Nutrient Dynamics ◽  
Treatment Plant ◽  
Nutrient Concentrations ◽  
Biological Processes ◽  
Overlying Water ◽  
Wwtp Effluent ◽  
Approaches To Study ◽  
Experimental Approaches ◽  
Study Sites

Abstract Uptake and regeneration fluxes and concentrations of nutrients, i.e., nitrate (NO3−), ammonium (NH4+), phosphate (PO43−) and dissolved organic carbon (DOC), were evaluated upstream and downstream of a wastewater treatment plant (WWTP) in the River Wandle, UK, from July to October 2019. Using chamber techniques, water-specific nutrient concentrations were measured at two exposures (3 and 10 min) to calculate fluxes. The WWTP effluent contributed to elevated concentrations and modified flux rates, resulting in significant differences at the study sites. Compared with summer, the concentrations of NO3− and DOC increased while NH4+ and PO43− decreased in autumn. Nutrient fluxes varied both temporally and spatially in uptake (i.e., storage in sediments) or regeneration (i.e., release into river water). Under the actions of physical and biological processes, the fluxes of NO3− and NH4+ showed opposite flux directions. Dissolved oxygen (DO) and bioabsorption mainly affected PO43− and DOC fluxes, respectively. Specifically, across all sites, NO3− was −0.01 to +0.02 mg/(m2 s), NH4+ was −29 to +2 μg/(m2 s), PO43− was −2.0 to +0.5 μg/(m2 s), and DOC was −0.01 to +0.05 mg/(m2 s). Further, we did find that these variations were related to nutrient concentrations in the overlying water. Our results provide further evidence to show that reductions in river nutrients are paramount for improving river ecological conditions. Additionally, we suggest that more research is needed to evaluate chamber-based experimental approaches to make them more comparable to in-situ flux methods. Highlights • Sewage effluent resulted in elevated nutrient concentrations and modified fluxes. • Flux was affected by initial nutrient concentrations, DO and microbial activity. • Inexpensive approaches to study nutrient dynamics are needed for river restoration.

scholarly journals Modelling the Quality of Bathing Waters in the Adriatic Sea

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1525
Author(s):  
Christian Ferrarin ◽  
Pierluigi Penna ◽  
Antonella Penna ◽  
Vedrana Spada ◽  
Fabio Ricci ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Management Tool ◽  
Negative Consequences ◽  
Sea Temperature ◽  
Bathing Water Directive ◽  
Bathing Waters ◽  
Diffusion Dynamics ◽  
Study Sites

The aim of this study is to develop a relocatable modelling system able to describe the microbial contamination that affects the quality of coastal bathing waters. Pollution events are mainly triggered by urban sewer outflows during massive rainy events, with relevant negative consequences on the marine environment and tourism and related activities of coastal towns. A finite element hydrodynamic model was applied to five study areas in the Adriatic Sea, which differ for urban, oceanographic and morphological conditions. With the help of transport-diffusion and microbial decay modules, the distribution of Escherichia coli was investigated during significant events. The numerical investigation was supported by detailed in situ observational datasets. The model results were evaluated against water level, sea temperature, salinity and E. coli concentrations acquired in situ, demonstrating the capacity of the modelling suite in simulating the circulation in the coastal areas of the Adriatic Sea, as well as several main transport and diffusion dynamics, such as riverine and polluted waters dispersion. Moreover, the results of the simulations were used to perform a comparative analysis among the different study sites, demonstrating that dilution and mixing, mostly induced by the tidal action, had a stronger effect on bacteria reduction with respect to microbial decay. Stratification and estuarine dynamics also play an important role in governing microbial concentration. The modelling suite can be used as a beach management tool for improving protection of public health, as required by the EU Bathing Water Directive.

scholarly journals Natural dimethyl sulfide gradients would lead marine predators to higher prey biomass

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Kylie Owen ◽  
Kentaro Saeki ◽  
Joseph D. Warren ◽  
Alessandro Bocconcelli ◽  
David N. Wiley ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Dimethyl Sulfide ◽  
Zooplankton Biomass ◽  
Foraging Success ◽  
Spatially Correlated ◽  
Prey Biomass ◽  
Marine Predators ◽  
Predator Foraging ◽  
The Impact

AbstractFinding prey is essential to survival, with marine predators hypothesised to track chemicals such as dimethyl sulfide (DMS) while foraging. Many predators are attracted to artificially released DMS, and laboratory experiments have shown that zooplankton grazing on phytoplankton accelerates DMS release. However, whether natural DMS concentrations are useful for predators and correlated to areas of high prey biomass remains a fundamental knowledge gap. Here, we used concurrent hydroacoustic surveys and in situ DMS measurements to present evidence that zooplankton biomass is spatially correlated to natural DMS concentration in air and seawater. Using agent simulations, we also show that following gradients of DMS would lead zooplankton predators to areas of higher prey biomass than swimming randomly. Further understanding of the conditions and scales over which these gradients occur, and how they are used by predators, is essential to predicting the impact of future changes in the ocean on predator foraging success.

The role of forest deadwood in rockfall protection

2021 ◽  
Author(s):  
Adrian Ringenbach ◽  
Peter Bebi ◽  
Perry Bartelt ◽  
Andrin Caviezel
Keyword(s):  
Basal Area ◽  
Spruce Forest ◽  
Runout Distance ◽  
In Situ Sensors ◽  
Efficient Protection ◽  
Cost Efficient ◽  
Study Sites ◽  
Rockfall Protection

<p>Forests with a high density and basal area of living trees are known for their function as natural and cost-efficient protection against rockfall. The role of deadwood, however, is less understood. We address this knowledge gap in this contribution as we present the results of repeated real-scale experiments in a) a montane beech-spruce forest with and without deadwood and b) in a subalpine scrub mountain pine-spruce forest with deadwood. We used artificial rocks with either an equant or platy shape, masses between 45 kg and 800 kg (≈ 0.3 m3), and equipped with in-situ sensors to gain insights into rotational velocities and impact-accelerations. Clusters of deadwood and erected root plates reduced the mean runout distance at both study sites. For site a), we found that more rocks were stopped behind lying than living trees and that the stopping effect of deadwood was greater for equant compared to platy rock shapes. Site b) revealed a braking effect of scrub mountain pines for relatively small (45 kg), but also a visible reduction in rotational velocities for the 800 kg rocks sensor stream. We conclude that deadwood must be taken into account in rockfall modeling and the management of rockfall protection forests.</p>

scholarly journals When losing your nuts increases your reproductive success: sandalwood (Santalum spicatum) nut caching by the woylie (Bettongia penicillata)

2015 ◽  
Vol 21 (3) ◽  
pp. 243 ◽  
Author(s):  
Marie Murphy ◽  
Kay Howard ◽  
Giles E. St J. Hardy ◽  
Bernard Dell
Keyword(s):  
Recruitment Rate ◽  
Primary Method ◽  
Seed Disperser ◽  
The Past ◽  
Successful Recruitment ◽  
Bettongia Penicillata ◽  
Santalum Spicatum ◽  
Study Sites ◽  
Germinated Seeds

To regenerate sandalwood (Santalum spicatum) stands in south-western Australia it is necessary to understand the complex relationship between woylies (Bettongia penicillata ogilbyi) and sandalwood. Sandalwood requires a seed disperser for successful recruitment and in the past the critically endangered woylie played an important role in dispersing and caching seeds, but it is not clear whether this mutualistic and antagonistic relationship is beneficial to regeneration efforts. An enclosure in a woodland and 46Scandium-labelled seeds, enabled study of the in situ predation of seeds, caching, the fate of cached seeds, the detection of cached seeds and predation of germinated seeds. Woylies preferentially cached sandalwood, then S. acuminatum seeds, before any interest was shown in Acacia acuminata and Gastrolobium microcarpum seeds, which were virtually all eaten in situ. Of a further 500 radiolabelled and individually numbered sandalwood seeds deployed, 42.2% were eaten in situ, 20.8% had an unknown fate and 37% were cached, with some seeds being recached up to four times. After nine months, only four cached seeds remained undisturbed. Olfaction appeared to be the primary method of cache detection. To examine the recruitment rate of cached seeds, the fate of 89 transplanted sandalwood seedlings at two study sites was followed. After one month 38% were intact and growing, but half of the transplanted seedlings were dug up and the remaining endosperm was eaten in situ or taken away. The results highlight the potential of providing seed supplies, including sandalwood seeds and seeds of their hosts, to seed-dispersal marsupials for passive ecosystem repair.

Biological processes in modelling soil functions – a balancing act between too complex and too simple

2021 ◽  
Author(s):  
Sara König ◽  
Ulrich Weller ◽  
Thomas Reitz ◽  
Bibiana Betancur-Corredor ◽  
Birgit Lang ◽  
...  
Keyword(s):  
Nutrient Cycling ◽  
Microbial Activity ◽  
Community Dynamics ◽  
Spatial Scales ◽  
Simulation Models ◽  
Microbial Processes ◽  
Biological Processes ◽  
Soil Functions ◽  
Management Options ◽  
The Impact

<p>Mechanistic simulation models are an essential tool for predicting soil functions such as nutrient cycling, water filtering and storage, productivity and carbon storage as well as the complex interactions between these functions. Most soil functions are driven or affected by soil organisms. Yet, biological processes are often neglected in soil function models or implicitly described by rate parameters. This can be explained by the high complexity of the soil ecosystem with its dynamic and heterogeneous environment, and by the range of temporal and spatial scales these processes are taking place at. On the other hand, the technical capabilities to explore microbial activity and communities in soil has greatly improved, resulting in new possibilities to understand soil microbial processes on various scales.</p><p>However, to integrate such biological processes in soil modelling, we need to find the right level of detail. Here, we present a systemic soil model approach to simulate the impact of different management options and changing climate on soil functions integrating biological activity on the profile scale. We use stoichiometric considerations to simulate microbial processes involved in different soil functions without explicitly describing community dynamics or functional groups. With this approach we are able to mechanistically describe microbial activity and its impact on the turnover of organic matter and nutrient cycling as driven by agricultural soil management.</p><p>Further, we discuss general challenges and ongoing developments to additionally consider, e.g., microbe-fauna-interactions or microbial feedback with soil structure dynamics.</p>

Glycan Labeling and Analysis in Cells and In Vivo

2021 ◽  
Vol 14 (1) ◽  
pp. 363-387
Author(s):  
Bo Cheng ◽  
Qi Tang ◽  
Che Zhang ◽  
Xing Chen
Keyword(s):  
Chemical Modification ◽  
Biological Function ◽  
Biological Processes ◽  
Affinity Tags ◽  
Functional Roles ◽  
Antibody Conjugates ◽  
Living Organisms ◽  
In Cells

As one of the major types of biomacromolecules in the cell, glycans play essential functional roles in various biological processes. Compared with proteins and nucleic acids, the analysis of glycans in situ has been more challenging. Herein we review recent advances in the development of methods and strategies for labeling, imaging, and profiling of glycans in cells and in vivo. Cellular glycans can be labeled by affinity-based probes, including lectin and antibody conjugates, direct chemical modification, metabolic glycan labeling, and chemoenzymatic labeling. These methods have been applied to label glycans with fluorophores, which enables the visualization and tracking of glycans in cells, tissues, and living organisms. Alternatively, labeling glycans with affinity tags has enabled the enrichment of glycoproteins for glycoproteomic profiling. Built on the glycan labeling methods, strategies enabling cell-selective and tissue-specific glycan labeling and protein-specific glycan imaging have been developed. With these methods and strategies, researchers are now better poised than ever to dissect the biological function of glycans in physiological or pathological contexts.

scholarly journals Abundance and Taxonomic Diversity of Bacteria Inhabiting the Sediment-Water Interface in a Marine Harbor Channel

2019 ◽  
Vol 54 (3) ◽  
pp. 407-418
Author(s):  
Piotr Perliński ◽  
Zbigniew J. Mudryk ◽  
Marta Zdanowicz
Keyword(s):  
Seasonal Fluctuation ◽  
Taxonomic Diversity ◽  
Taxonomic Composition ◽  
Bacterial Number ◽  
Water Interface ◽  
Phylogenetic Groups ◽  
Cell Counts ◽  
Study Sites ◽  
Taxonomic Groups

Abstract The abundance of bacteria inhabiting the sediment-water interface and their taxonomic composition were determined with the fluorescence in situ hybridization (FISH) method in a marine harbor channel in Ustka. Among bacteria inhabiting the studied layer Gammaproteobacteria (1.4 cells 108·dm−3) and Cytophaga-Flavobacterium (1.1 cells 108·dm−3) dominated. Vibrio and Pseudomonas represented only a small fraction of the total cell counts. All taxonomic groups of studied bacteria show significant positive correlation between their abundance. The total bacterial number varied from 3.3 to 23.5 cells 108·dm−3 and their biomass oscillated from 39.4 to 282.4 μg C·dm−3. This parameter differed along horizontal profiles, while there were no significant differences in the abundance of the studied taxonomic groups among the study sites of the channel in Ustka. The total number of bacteria as well as the abundance of bacterial phylogenetic groups were subject to seasonal fluctuation in the studied water basin.

scholarly journals Remote sensing of ecosystem light use efficiency with MODIS-based PRI

2011 ◽  
Vol 8 (1) ◽  
pp. 189-202 ◽  
Author(s):  
A. Goerner ◽  
M. Reichstein ◽  
E. Tomelleri ◽  
N. Hanan ◽  
S. Rambal ◽  
...  
Keyword(s):  
Meteorological Data ◽  
Vapour Pressure Deficit ◽  
Ground Truth ◽  
Light Use Efficiency ◽  
Wide Range ◽  
Evaluation Exercise ◽  
Use Efficiency ◽  
Study Sites ◽  
Absorbed Photosynthetically Active Radiation

Abstract. Several studies sustained the possibility that a photochemical reflectance index (PRI) directly obtained from satellite data can be used as a proxy for ecosystem light use efficiency (LUE) in diagnostic models of gross primary productivity. This modelling approach would avoid the complications that are involved in using meteorological data as constraints for a fixed maximum LUE. However, no unifying model predicting LUE across climate zones and time based on MODIS PRI has been published to date. In this study, we evaluate the effectiveness with which MODIS-based PRI can be used to estimate ecosystem light use efficiency at study sites of different plant functional types and vegetation densities. Our objective is to examine if known limitations such as dependence on viewing and illumination geometry can be overcome and a single PRI-based model of LUE (i.e. based on the same reference band) can be applied under a wide range of conditions. Furthermore, we were interested in the effect of using different faPAR (fraction of absorbed photosynthetically active radiation) products on the in-situ LUE used as ground truth and thus on the whole evaluation exercise. We found that estimating LUE at site-level based on PRI reduces uncertainty compared to the approaches relying on a maximum LUE reduced by minimum temperature and vapour pressure deficit. Despite the advantages of using PRI to estimate LUE at site-level, we could not establish an universally applicable light use efficiency model based on MODIS PRI. Models that were optimised for a pool of data from several sites did not perform well.

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