scholarly journals Short-term effects of increased CO2, nitrate and temperature on photosynthetic activity in Ulva rigida (Chlorophyta) estimated by different pulse amplitude modulated fluorometers and oxygen evolution†

2020 ◽  
Author(s):  
F L Figueroa ◽  
J Bonomi-Barufi ◽  
P S M Celis-Plá ◽  
U Nitschke ◽  
F Arenas ◽  
...  
Keyword(s):  
Marine Macroalgae ◽  
Ex Situ ◽  
O2 Evolution ◽  
Nitrate Content ◽  
Ulva Rigida ◽  
Short Term ◽  
Ps Ii ◽  
The Impact ◽  
Short Term Effects

Abstract Short-term effects of pCO2 (700–380 ppm; High carbon (HC) and Low carbon (LC), respectively) and nitrate content (50–5 µM; High nitrogen (HN) and Low nitrogen (LN), respectively on photosynthesis were investigated in Ulva rigida (Chlorophyta) under solar radiation (in-situ) and in the laboratory under artificial light (ex-situ). After six days of incubation at ambient temperature (AT), algae were subjected to a 4 °C temperature increase (AT+4 °C) for 3 d. Both in-situ and ex-situ maximal electron transport rate (ETRmax) and in situ gross photosynthesis (GP), measured by O2 evolution, presented highest values under HCHN, and lowest under HCLN, across all measuring systems. Maximal quantum yield (Fv/Fm), and ETRmax of photosystem (PS) II [ETR(II)max] and PSI [ETR(I)max], decreased under HCLN at AT+4 °C. Ex situ ETR was higher than in situ ETR. At noon, Fv/Fm decreased (indicating photoinhibition), whereas ETR(II)max and maximal non-photochemical quenching (NPQmax) increased. ETR(II)max decreased under AT+ 4 °C in contrast to Fv/Fm, photosynthetic efficiency (α ETR) and saturated irradiance (EK). Thus, U. rigida exhibited a decrease in photosynthesis under acidification, changing LN, and AT+4 °C. These results emphasize the importance of studying the interaction between environmental parameters using in-situ versus ex-situ conditions, when aiming to evaluate the impact of global change on marine macroalgae.

Soil seed bank and vegetation dynamics in Sahelian fallows; the impact of past cropping and current grazing treatments

2004 ◽  
Vol 20 (6) ◽  
pp. 683-691 ◽  
Author(s):  
Bruno Hérault ◽  
Pierre Hiernaux
Keyword(s):  
Seed Bank ◽  
Management Practices ◽  
Soil Seed Bank ◽  
Residual Effects ◽  
Ex Situ ◽  
Phosphorus Fertilizer ◽  
Wet Season ◽  
Seed Extraction ◽  
The Impact

The soil seed bank in a 5-y-old Sahelian fallow was studied through seed extraction and compared with germinations recorded either in controlled conditions, ex situ in a glasshouse, or in the field. The influence of phosphorus fertilizer and mulch application during the preceding crop period, and that of seasonal grazing regimes applied the last 2 y of fallowing, were assessed on the composition of the seed stock. Ctenium elegans, Fimbristylis hispidula, Merremia pinnata and Phyllanthus pentandrus accounted together for 75% of extracted seeds, 72% of ex situ, and 62% of in situ seedlings. Mulch treatment was correlated with the first axis of the canonical correspondence analyses performed on the seedling datasets. Mulch and phosphorus fertilizer treatments held similar responses, as they both favoured the seed bank of erect dicotyledons such as P. pentandrus and Cassia mimosoides. On the whole, the effects of grazing remained modest compared with the residual effects of past crop management practices. However, seedling densities increased as a result of dry-season grazing, while the soil seed bank decreased with wet-season grazing. Grazing also reduced the spatial heterogeneity of the seed bank rather than the overall number of species.

The importance of the turbulent ship wake regime for pollutant fate and transport

2021 ◽  
Author(s):  
Amanda T. Nylund ◽  
Rickard Bensow ◽  
Mattias Liefvendahl ◽  
Arash Eslamdoost ◽  
Anders Tengberg ◽  
...  
Keyword(s):  
Fate And Transport ◽  
In Situ Measurements ◽  
Ex Situ ◽  
Landsat 8 ◽  
Turbulent Regime ◽  
Near Wake ◽  
Ship Wake ◽  
Spatiotemporal Scales ◽  
The Impact

<p>This interdisciplinary study with implications for fate and transport of pollutants from shipping, investigates the previously overlooked phenomenon of ship induced mixing. When a ship moves through water, the hull and propeller induce a long-lasting turbulent wake. Natural waters are usually stratified, and the stratification influences both the vertical and horizontal extent of the wake. The altered turbulent regime in shipping lanes governs the distribution of discharged pollutants, e.g. PAHs, metals, nutrients and non-indigenous species. The ship related pollutant load follows the trend in volumes of maritime trade, which has almost tripled since the 1980s. In heavily trafficked areas there may be one ship passage every ten minutes; today shipping constitutes a significant source of pollution.</p><p>To understand the environmental impact of shipping related pollutants, it is essential to know their fate following regional scale transport. However, previous modelling efforts assuming discharge at the surface will not adequately reflect the input values in the regional models. Therefore, it is urgent to bridge the gaps between the spatiotemporal scales from high-resolution numerical modeling of the flow hydrodynamics around the ship, mixing processes and interaction of the ship and wake with stratification, and parameterization in regional oceanographic modeling. Here this knowledge gap is addressed by combining an array of methods; in situ measurements, remote sensing and numerical flow modeling.</p><p>A bottom-mounted Acoustic Doppler Current Profiler was placed under a ship lane, for <em>in-situ</em> measurements of the vertical and temporal expansion of turbulent wakes. In addition, <em>ex-situ</em> measurements with Landsat 8 Thermal Infrared Sensor were used to estimate the longevity and spatial extent of the thermal signal from ship wakes. The computational modelling was conducted using well resolved 3D RANS modelling for the hull and the near wake (up to five ship lengths aft), a method typically used for the near wake behaviour in analysing the propulsion system. As this is not feasible to use for a far wake analysis, the predicted wake is then used as input for a 2D+time modelling for the sustained wake up to 30min after the ship passage. These results, both from measurements and numerical models, are then combined to analyse how ship-induced turbulence influence at what depth discharged pollutants will be found.</p><p>This first step to cover the mesoscales of the turbulent ship wake is necessary to assess the impact of ship related pollution. In-situ measurements show median wake depth 13.5m (max 31.5m) and median longevity 10min (max 29min). Satellite data show median thermal wake signal 13.7km (max 62.5km). A detailed simulation model will only be possible to use for the first few 100m of the ship wake, but the coupling to a simplified 2D+time modelling shows a promising potential to bridge our understanding of the impact of the ship wake on the larger scales. Our model results indicate that the natural stratification affects the distribution and retention of pollutants in the wake region. The depth of discharge and the wake turbulence characteristics will in turn affect the fate and transport of pollutants on larger spatiotemporal scales.</p>

Short-term effects of carbon source on the competition of polyphosphate accumulating organisms and glycogen accumulating organisms

2004 ◽  
Vol 50 (10) ◽  
pp. 139-144 ◽  
Author(s):  
A. Oehmen ◽  
Z. Yuan ◽  
L.L. Blackall ◽  
J. Keller
Keyword(s):  
Carbon Source ◽  
In Situ Hybridisation ◽  
Operating Conditions ◽  
Fluorescence In Situ Hybridisation ◽  
Biological Phosphorus Removal ◽  
Short Term ◽  
Uptake Rates ◽  
Polyphosphate Accumulating Organisms ◽  
The Impact ◽  
Short Term Effects

The effectiveness of enhanced biological phosphorus removal (EBPR) systems is directly affected by the competition of polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). This study investigated the short-term effects of carbon source on PAO and GAO performance. The tests were designed to clearly determine the impact of volatile fatty acid (VFA) composition on the performance of two types of biomass, one enriched for PAOs and the other for GAOs. The two populations were enriched in separate reactors using identical operating conditions and very similar influent compositions with acetate as the sole carbon source. The only difference was that a very low level of phosphorus was present in the influent to the GAO reactor. The abundance of PAOs and GAOs was quantified using fluorescence in-situ hybridisation. The results clearly show that there are some very distinctive differences between PAOs and GAOs in their ability to utilise different carbon substrates. While both are able to take up acetate rapidly and completely, the GAOs are far slower at consuming propionate than the PAOs during short-term substrate changes. This provides a potentially highly valuable avenue to influence the competition between PAOs and GAOs. Other VFAs studied seem to be less usable in the short term by both PAOs and GAOs, as indicated by their much lower uptake rates.

scholarly journals Short-term surface ice motion variations measured with a ground-based portable real aperture radar interferometer

2011 ◽  
Vol 57 (201) ◽  
pp. 53-60 ◽  
Author(s):  
Patrick Riesen ◽  
Tazio Strozzi ◽  
Andreas Bauder ◽  
Andreas Wiesmann ◽  
Martin Funk
Keyword(s):  
Line Of Sight ◽  
Interferometric Imaging ◽  
Short Term ◽  
Glacier Surface ◽  
Fast Acquisition ◽  
Surface Ice ◽  
The Impact ◽  
Real Aperture Radar ◽  
Aperture Radar

AbstractWe report measurements using a portable real aperture radar (Gamma Portable Radar Interferometer (GPRI)) for interferometric imaging of the surface ice motion on Gornergletscher, Switzerland, during the drainage of the adjacent ice-marginal lake Gornersee. The GPRI tracked the surface ice motion in line of sight over an area of ∼3 km2 down-glacier of Gornersee almost continuously during the drainage event. The displacement maps derived from the acquired interferograms capture the spatial distribution of the surface ice motion. Due to fast acquisition times of the microwave images, the GPRI was able to record sub-daily variations of the ice displacements, most likely caused by the impact of the Gornersee drainage on the ice motion of Gornergletscher. In situ point measurements of the ice displacement agree reasonably well with the results obtained by the GPRI and highlight the use of the GPRI for high-resolution measurements of glacier surface ice motion.

Soil copper contamination effect on carbon mineralisation: evidence of a soil CO2 emission decrease from literature review

2020 ◽  
Author(s):  
Sereni Laura ◽  
Guenet Bertrand ◽  
Crouzet Olivier ◽  
Lamy Isabelle
Keyword(s):  
Soil Respiration ◽  
Soil Carbon ◽  
Ex Situ ◽  
Soil Parameters ◽  
Copper Contamination ◽  
Carbon Mineralisation ◽  
Cu Contamination ◽  
C Mineralisation ◽  
The Impact

<p>Among all pollutants, copper (Cu) is of major environmental and toxicological concern with contamination from various origins. Moreover as a cation, Cu is easily complexed by the negatively charged soil organic matter (OM) inducing high concentrations in upper layers of soils where OM dominates. Due to its biotic and abiotic interactions with soil constituents Cu is expected to affect several soil processes among them the soil respiration, but studies provided contrasting results as soil respiration have been shown to decrease or increase with soil contamination depending on the studies.</p><p>In this study, we aimed at assessing how soil respiration is affected by Cu contamination in order to quantifying as a first approach the GHG emissions for a contaminated soil. We performed a quantitative review of literature focusing on soil heterotrophic respiration (thus excluding autotrophic respiration from plants) which aimed at 1) assessing the impact of a copper contamination on soil carbon (C) mineralisation and thus CO<sub>2</sub> emissions, and 2) hierarchizing the determinants of such an impact on C mineralisation compare to the influence of pedo-climatic soil parameters such as pH, clay percentage or the type of climate.</p><p>On the basis of a selection of roughly 390 literature data, global main results showed a decrease in soil CO<sub>2</sub> emission with an increase in soil Cu contamination. Data from ex situ spiking experiments could be easily differentiated from the ones originated from in situ natural contamination due to their sharper decrease in soil organic carbon mineralisation. Interestingly, ex situ spikes data on the short term provided a threshold: an increase in soil CO<sub>2</sub> emissions was noticed for data below total soil Cu content of 180 mg kg<sup>-1</sup> while a decrease was observed above this concentration. On the contrary, long-term in situ contamination due to anthropogenic activities (urbanisation, agriculture …) did not significantly impact soil carbon mineralisation except when we focused on the high inputs of industrial contamination (smelter, composted plant…). Soil pH was found as a variable of interest as acidic soils were more sensitive to Cu contamination for C mineralisation than neutral or alkaline soils, while the % of clay and the type of climate did not add explanation to the variation in C mineralisation. These results are discussed and the collected data allowed us to propose a general equation quantifying how soil respiration can be affected by a Cu contamination.</p>

The impact of noise on the short-term effects of traffic-related air pollution on heart rate variability in young healthy adults

2013 ◽  
Vol 2013 (1) ◽  
pp. 4244
Author(s):  
Jing Huang ◽  
Furong Deng ◽  
Shaowei Wu ◽  
Henry Lu ◽  
Yu Hao ◽  
...  
Keyword(s):  
Heart Rate ◽  
Air Pollution ◽  
Heart Rate Variability ◽  
Healthy Adults ◽  
Short Term ◽  
The Impact ◽  
Short Term Effects

Short-Term Impact of Cancer Prevention and Screening Activities on Quality of Life

2004 ◽  
Vol 22 (5) ◽  
pp. 943-952 ◽  
Author(s):  
Jennifer Cullen ◽  
Marc D. Schwartz ◽  
William F. Lawrence ◽  
Joe V. Selby ◽  
Jeanne S. Mandelblatt
Keyword(s):  
Quality Of Life ◽  
Health Status ◽  
Cancer Prevention ◽  
Depression Symptoms ◽  
Original Research ◽  
Short Term ◽  
The Impact ◽  
Short Term Effects

Purpose There are few data on the short-term effects of participating in cancer prevention activities, undergoing genetic risk assessment, or having routine screening. The objective of this article is to systematically review existing research on short-term effects of prevention, genetic counseling and testing, and screening activities on quality of life. Methods We conducted a MEDLINE search for original research studies that were published between January 1, 1985, and December 31, 2002, and conducted in North America or Western Europe. Data were abstracted and summarized using a standardized format. Results We reviewed 210 publications. Most studies focused on psychological states (anxiety, depression), symptoms, or general health status. One hundred thirty-one studies used 51 previously validated noncancer instruments. Many researchers (12.6%) also added cancer-specific measures, such as perceived cancer risk or symptom indices. Only one study measured satisfaction or quality of provider-client communication. While one report examined lost workdays, no other economic consequences of short-term outcomes were evaluated. Among seven studies that assessed short-term outcomes preferences, only four specifically used time trade-off or linear rating scale methods. No study used standard gamble or willingness-to-pay methods. The overwhelming majority of research indicated that short-term effects were transient. Only two studies linked short-term effects to long-term cancer-related health behaviors such as repeat screening. Conclusion There is considerable heterogeneity in short-term outcome measurement. Clinicians need to be aware of potential for short-term, transient adverse effects. The impact of short-term experiences should to be linked to long-term health status and use of services.

Productivity and nitrogen use of maize as affected by in situ and ex situ green manuring in major and minor seasons of tropical Asia

2009 ◽  
Vol 57 (3) ◽  
pp. 285-296 ◽  
Author(s):  
U. Sangakkara ◽  
P. Stamp
Keyword(s):  
Seed Yield ◽  
N Use Efficiency ◽  
Ex Situ ◽  
Green Manures ◽  
Smallholder Farming ◽  
Green Manuring ◽  
Use Efficiency ◽  
The Impact ◽  
N Use

Green manuring is considered an important agronomic practice for smallholder farming systems in the tropics. Different species of legumes and non-legumes are applied either as ex situ or in situ green manures. Thus a field study conducted under rainfed conditions in Sri Lanka compared the effect of in situ and ex situ green manuring using two popular green manures ( Crotolaria juncea — a legume and Tithonia diversifolia — a non-legume) on the growth, seed yield and N use pattern of maize ( Zea mays ), the most popular upland cereal in the Asian tropics, grown with high and low N rates, in the two seasons that correspond to the monsoonal rains. In situ green manuring, especially with crotolaria, increased the growth, seed yield and N use efficiency of maize when compared to the ex situ addition of similar quantities of the green manure. The impact was also greater in the minor season, when the crop was subjected to moisture stress conditions. The benefits of in situ green manuring with tithonia were lower than those due to crotolaria. In situ green manuring with tithonia also led to a greater increase in growth, seed yield and N use efficiency in maize compared to ex situ green manuring with this species. The green manures, especially in situ application, also increased the benefits of enhanced rates of N fertilizer to the crops in both seasons, with greater use efficiency in the major season. The study showed the benefits of green manuring (both in and ex situ ) for obtaining higher yields of maize in the growing seasons of the Asian tropics, especially the in situ application of legume species.

Electrochemical Characterization of Graphite-Zero-Valent Iron for 3-Monochloropropane-1,2-Diol (3-MCPD) Detection

2021 ◽  
Vol 1025 ◽  
pp. 20-25
Author(s):  
Farrah Aida Arris ◽  
Wan Nabilah Manan ◽  
Hatika Kaco ◽  
Ahmad Hakimi Shaffie ◽  
Mohd Shaiful Sajab
Keyword(s):  
Graphite Electrode ◽  
Electrical Current ◽  
Dip Coating ◽  
Zero Valent Iron ◽  
Ex Situ ◽  
Potential Range ◽  
Formation Method ◽  
The Impact

This study aims to investigate the feasibility of modifying graphite electrode with zero-valent iron (ZVI) to electrochemically detect the presence of 3-MCPD using two (2) deposition methods, namely dip coating and drop casting. Both methods were tested against in situ and ex situ ZVI formation method. Results showed that ex situ ZVI formation using drop casting method onto graphite electrode showed highest peak current when tested using cyclic voltammetry (CV). Results also showed that the 3-MCPD presence was detected at potential range of-25 mV to 45 mV due to the sudden spike in electrical current when tested using CV mode. The impact of this study is to provide a basis for further investigation of 3-MCPD detection in palm oil using electrochemical method due to its simplicity for the development of a portable, fast and reliable 3-MCPD sensor.

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