scholarly journals Determining the impact of flow velocities on reactive processes associated with Enterococcus faecalis JH2-2

2021 ◽  
Author(s):  
Aparna Chandrasekar ◽  
Martin Binder ◽  
Rudolf Liedl ◽  
Thomas Berendonk
Keyword(s):  
Dissolved Oxygen ◽  
Nutrient Concentrations ◽  
Residence Times ◽  
Biological Processes ◽  
Mean Flow ◽  
Colloidal Transport ◽  
Infiltration Rates ◽  
The Impact ◽  
Reactive Processes ◽  
Flow Velocities

Abstract This study focuses on the impact of infiltration rates on colloidal transport and reactive processes associated with E. faecalis JH2-2 using water-saturated sediment columns. The infiltration rates influence the physical transport of bacteria by controlling the mean flow velocity. This, in turn, impacts biological processes in pore water owing to the higher or lower residence time of the bacteria in the column. In the present study, continuous injection of E. faecalis (suspended in saline water with varying conditions of dissolved oxygen and nutrient concentrations) into a lab-scale sediment column was performed at flow velocities of 0.02 cm min−1 and 0.078 cm min−1, i.e., at residence times of 1–5 hours. The impact of residence times on reactive processes is significant for field scale setups. A process-based model with a first-order rate coefficient for each biological process was fitted for each obtained condition-specific dataset from the experimental observations (breakthrough curves). The coefficients were converted to a dimensionless form to facilitate the comparison of biological processes. These results indicate that the processes of attachment and growth were flow-dependent. The growth process in the absence of dissolved oxygen was the most dominant process, with a Damkoehler number of approximately 48.

The use of artificial oxygenation to reduce nutrient availability in the Canning River, Western Australia

2001 ◽  
Vol 43 (9) ◽  
pp. 133-144 ◽  
Author(s):  
B. Greenop ◽  
K. Lovatt ◽  
M. Robb
Keyword(s):  
Dissolved Oxygen ◽  
Water Column ◽  
Western Australia ◽  
Algal Blooms ◽  
Positive Impact ◽  
Monitoring Program ◽  
Nutrient Concentrations ◽  
Nitrogen And Phosphorus ◽  
The Impact ◽  
Oxygen Concentrations

Artificial oxygenation has been used for two summer periods to improve the water quality of the Canning River in Perth, Western Australia. The project is part of the Swan Canning Cleanup Program, which aims to reduce the frequency and severity of nuisance and toxic algal blooms in the Swan-Canning estuary. The trials have proved that oxygenation has increased the dissolved oxygen concentrations in the water column, particularly in the bottom waters where dissolved oxygen concentrations are frequently below a critical level of three milligrams per litre. Oxygenation has had a positive impact on nutrient concentrations in the water column and nitrogen cycling processes. Reductions in nutrient concentrations were highlighted by drops in ammonium and total phosphorus concentrations of 97% and 64% following the recommencement of oxygenation after a plant shutdown. Results of a microbiological study combined with the data analysis indicate that the number of nitrifying microbes have increased due to oxygenation. However, comparisons between oxygenated and control areas were inconclusive about the ability of the oxygenation plant to reduce total nitrogen and phosphorus levels. This could be explained by factors such as spatial variability, water flow during the trials and measurement limitations in the monitoring program. Future work will concentrate on assessing the impact of the oxygenation plant on nutrient concentrations.

scholarly journals Analysis of Dissolved Oxygen and Nutrients in Zhanjiang Bay and the Adjacent Sea Area in Spring

2020 ◽  
Vol 12 (3) ◽  
pp. 889
Author(s):  
Dongyang Fu ◽  
Yafeng Zhong ◽  
Fajin Chen ◽  
Guo Yu ◽  
Xiaolong Zhang
Keyword(s):  
Dissolved Oxygen ◽  
Phytoplankton Bloom ◽  
Inorganic Nitrogen ◽  
Guangdong Province ◽  
Nutrient Concentrations ◽  
Western Coast ◽  
Chemical Parameters ◽  
Physico Chemical ◽  
Sea Area ◽  
The Impact

As a semi-closed bay with narrow bay mouths, the distribution of nutrients in Zhanjiang Bay was different from bays with open bay mouths and rivers with large flows. It is important to study the water quality of Zhanjiang Bay to determine the impact of human activities on this semi-closed bay. Based on field survey data in spring, the spatial distribution of nutrients and other physico-chemical parameters was investigated, in order to study the geochemical characteristics of nutrients in semi-closed bays. Higher nutrient concentrations were observed in the inner and outer bays, but lower concentrations were observed at the bay mouth. With other analyses of physico-chemical parameters, the higher nutrient concentrations in the inner bay originated mainly from the diluted freshwater input from local developments and rivers. With the strong flow that exists along the western coast of Guangdong Province, the higher dissolved inorganic nitrogen (DIN) and SiO3–Si concentrations along the outer bay may be influenced by discharge from local cities in western Guangdong Province. There was stronger phytoplankton assimilation at the bay mouth, which resulted in reduced nutrient concentrations in this area. Although the hydrographic characteristics between the inner bay and outer bay were significantly different, the distribution of chlorophyll-a (Chla) levels was similar. However, we found significantly low dissolved oxygen (DO) and high apparent oxygen utilisation (AOU) consumption levels in the inner bay, and high DO and low AOU levels in the outer bay, which suggested that decomposition was more important than photosynthesis in the closed bay, even in spring during the phytoplankton bloom.

Effects of a barrage on flushing and water quality in the Fitzroy River estuary, Queensland

1981 ◽  
Vol 32 (1) ◽  
pp. 57 ◽  
Author(s):  
DW Connell ◽  
BM Bycroft ◽  
GJ Miller ◽  
P Lather
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Chlorophyll A ◽  
River Estuary ◽  
Freshwater Inflow ◽  
Residence Times ◽  
Principal Mechanism ◽  
Before And After ◽  
The Impact ◽  
Fitzroy River

Tidal exchange was found to flush the Fitzroy River estuary at a comparatively slow rate, leading to residence times of substances in the estuary of approximately 8 months both before and after barrage construction. The principal mechanism of flushing is displacement by freshwater inflow which gives residence times of 0.2-3.5 months. Freshwater inflow has been decreased by barrage construction and residence times consequently increased. Salinity and dissolved oxygen, total phosphorus, filterable reactive phosphorus, oxidized nitrogen and chlorophyll a concentrations were measured at stations located 20 to 110 km upstream from the mouth of the Fitzroy River. This included that section containing the barrage which was constructed 5 km upstream from Rockhampton. Under conditions of high river discharge (22.6 × 108 m3) little variation in water quality was found, but under low discharge conditions (0.035 × 108 m3) substantial reductions in dissolved oxygen concentration and increases in nutrient and chlorophyll a concentrations were noted in the zone below the barrage. These results are indicative of the impact of barrage construction on water quality, but more detailed chemical and biological investigations would be needed to unequivocally evaluate water quality status.

Fluorescent potentiometric dyes for membrane-potential imaging

1994 ◽  
Vol 52 ◽  
pp. 166-167
Author(s):  
Leslie M. Loew
Keyword(s):  
Membrane Potential ◽  
Single Cells ◽  
Quantitative Imaging ◽  
Optical Recording ◽  
Biological Processes ◽  
Major Focus ◽  
The Past ◽  
Excitable Systems ◽  
Major Application ◽  
The Impact

A major application of potentiometric dyes has been the multisite optical recording of electrical activity in excitable systems. After being championed by L.B. Cohen and his colleagues for the past 20 years, the impact of this technology is rapidly being felt and is spreading to an increasing number of neuroscience laboratories. A second class of experiments involves using dyes to image membrane potential distributions in single cells by digital imaging microscopy - a major focus of this lab. These studies usually do not require the temporal resolution of multisite optical recording, being primarily focussed on slow cell biological processes, and therefore can achieve much higher spatial resolution. We have developed 2 methods for quantitative imaging of membrane potential. One method uses dual wavelength imaging of membrane-staining dyes and the other uses quantitative 3D imaging of a fluorescent lipophilic cation; the dyes used in each case were synthesized for this purpose in this laboratory.

Evaluation of Toxicity in Receiving Streams

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2357-2360
Author(s):  
J. Zagorc-Koncan ◽  
M. Dular
Keyword(s):  
Dissolved Oxygen ◽  
Toxic Substances ◽  
Toxicity Evaluation ◽  
Copper Cyanide ◽  
Polluted River ◽  
Design Information ◽  
Point Of Entry ◽  
Receiving Stream ◽  
The Impact

A laboratory river model for the study of self-purification inhibition in a stream containing toxic substances is presented. It enables an engineering - technological prediction of the impact of toxic substances or wastewaters on dissolved oxygen (DO) profile in an organically polluted river downstream from the point of entry of toxic effluent thus providing rapidly and inexpensively significant design information to an environmental scientist or engineer. The method was applied to the toxicity evaluation of wastewaters from electroplating industry. The effects of copper, cyanide (representing two significant constituents of this type of wastewaters) and wastewater from electroplating industry on the biodegradation of organic municipal pollution in receiving stream were evaluated experimentally.

Considering the impact of intermittent discharges when modelling overflows

1998 ◽  
Vol 38 (10) ◽  
pp. 23-30
Author(s):  
Sarah Jubb ◽  
Philip Hulme ◽  
Ian Guymer ◽  
John Martin
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Preliminary Investigation ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Combined Sewer Overflows ◽  
River Hydraulics ◽  
Combined Sewer ◽  
The Impact ◽  
Curve Equation

This paper describes a preliminary investigation that identified factors important in the prediction of river water quality, especially regarding dissolved oxygen (DO) concentration. Intermittent discharges from combined sewer overflows (CSOs) within the sewerage, and overflows at water reclamation works (WRW) cause dynamic conditions with respect to both river hydraulics and water quality. The impact of such discharges has been investigated under both wet and dry weather flow conditions. Data collected from the River Maun, UK, has shown that an immediate, transient oxygen demand exists downstream of an outfall during storm conditions. The presence of a delayed oxygen demand has also been identified. With regard to modelling, initial investigations used a simplified channel and the Streeter-Phelps (1925) dissolved oxygen sag curve equation. Later, a model taking into account hydrodynamic, transport and dispersion processes was used. This suggested that processes other than water phase degradation of organic matter significantly affect the dissolved oxygen concentration downstream of the location of an intermittent discharge. It is proposed that the dynamic rate of reaeration and the sediment oxygen demand should be the focus of further investigation.

Self-Acceleration in the Parameterization of Orographic Gravity Wave Drag

2010 ◽  
Vol 67 (8) ◽  
pp. 2537-2546 ◽  
Author(s):  
John F. Scinocca ◽  
Bruce R. Sutherland
Keyword(s):  
Gravity Wave ◽  
Middle Atmosphere ◽  
Wave Train ◽  
Leading Edge ◽  
Wave Theory ◽  
Wave Drag ◽  
Tuning Parameter ◽  
Mean Flow ◽  
Propagating Waves ◽  
The Impact

Abstract A new effect related to the evaluation of momentum deposition in conventional parameterizations of orographic gravity wave drag (GWD) is considered. The effect takes the form of an adjustment to the basic-state wind about which steady-state wave solutions are constructed. The adjustment is conservative and follows from wave–mean flow theory associated with wave transience at the leading edge of the wave train, which sets up the steady solution assumed in such parameterizations. This has been referred to as “self-acceleration” and it is shown to induce a systematic lowering of the elevation of momentum deposition, which depends quadratically on the amplitude of the wave. An expression for the leading-order impact of self-acceleration is derived in terms of a reduction of the critical inverse Froude number Fc, which determines the onset of wave breaking for upwardly propagating waves in orographic GWD schemes. In such schemes Fc is a central tuning parameter and typical values are generally smaller than anticipated from conventional wave theory. Here it is suggested that self-acceleration may provide some of the explanation for why such small values of Fc are required. The impact of Fc on present-day climate is illustrated by simulations of the Canadian Middle Atmosphere Model.

scholarly journals Bacterial Communities and Enzymatic Activities in Sediments of Long-Term Fish and Crab Aquaculture Ponds

2021 ◽  
Vol 9 (3) ◽  
pp. 501
Author(s):  
Zhimin Zhang ◽  
Qinghui Deng ◽  
Lingling Wan ◽  
Xiuyun Cao ◽  
Yiyong Zhou ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Enzymatic Activities ◽  
Nutrient Concentrations ◽  
Biological Processes ◽  
Farming Practices ◽  
Mitten Crab ◽  
Aquaculture Ponds ◽  
Pond Sediments ◽  
Sediment Ph

Aquaculture is among the most important and fastest growing agriculture sectors worldwide; however, it generates environmental impacts by introducing nutrient accumulations in ponds, which are possibly different and further result in complex biological processes in the sediments based on diverse farming practices. In this study, we investigated the effects of long-term farming practices of representative aquatic animals dominated by grass carp (GC, Ctenopharyngodon idella) or Chinese mitten crab (CMC, Eriocheir sinensis) on the bacterial community and enzyme activity of sediments from more than 15 years of aquaculture ponds, and the differences associated with sediment properties were explored in the two farming practices. Compared to CMC ponds, GC ponds had lower contents of TC, TN, and TP in sediments, and similar trends for sediment pH and moisture content. Sediment bacterial communities were significantly different between GC and CMC ponds, with higher bacterial richness and diversity in GC ponds. The bacterial communities among the pond sediments were closely associated with sediment pH, TC, and TN. Additionally, the results showed profoundly lower activities of β-1,4-glucosidase, leucine aminopeptidase, and phosphatase in the sediments of GC ponds than CMC ponds. Pearson’s correlation analysis further revealed strong positive correlations between the hydrolytic enzyme activities and nutrient concentrations among the aquaculture ponds, indicating microbial enzyme regulation response to sediment nutrient dynamics. Our study herein reveals that farming practices of fish and crab differently affect bacterial communities and enzymatic activities in pond sediments, suggesting nutrient-driven sediment biological processes in aquaculture ponds for different farming practices.

scholarly journals Citizen Science Tools Reveal Changes in Estuarine Water Quality Following Demolition of Buildings

2021 ◽  
Vol 13 (9) ◽  
pp. 1683
Author(s):  
Nandini Menon ◽  
Grinson George ◽  
Rajamohananpillai Ranith ◽  
Velakandy Sajin ◽  
Shreya Murali ◽  
...  
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Citizen Science ◽  
Secchi Depth ◽  
Lake Water Quality ◽  
Demolition Waste ◽  
Water Colour ◽  
Water Quality Variables ◽  
The Impact

Turbidity and water colour are two easily measurable properties used to monitor pollution. Here, we highlight the utility of a low-cost device—3D printed, hand-held Mini Secchi disk (3DMSD) with Forel-Ule (FU) colour scale sticker on its outer casing—in combination with a mobile phone application (‘TurbAqua’) that was provided to laymen for assessing the water quality of a shallow lake region after demolition of four high-rise buildings on the shores of the lake. The demolition of the buildings in January 2020 on the banks of a tropical estuary—Vembanad Lake (a Ramsar site) in southern India—for violation of Indian Coastal Regulation Zone norms created public uproar, owing to the consequences of subsequent air and water pollution. Measurements of Secchi depth and water colour using the 3DMSD along with measurements of other important water quality variables such as temperature, salinity, pH, and dissolved oxygen (DO) using portable instruments were taken for a duration of five weeks after the demolition to assess the changes in water quality. Paired t-test analyses of variations in water quality variables between the second week of demolition and consecutive weeks up to the fifth week showed that there were significant increases in pH, dissolved oxygen, and Secchi depth over time, i.e., the impact of demolition waste on the Vembanad Lake water quality was found to be relatively short-lived, with water clarity, colour, and DO returning to levels typical of that period of year within 4–5 weeks. With increasing duration after demolition, there was a general decrease in the FU colour index to 17 at most stations, but it did not drop to 15 or below, i.e., towards green or blue colour indicating clearer waters, during the sampling period. There was no significant change in salinity from the second week to the fifth week after demolition, suggesting little influence of other factors (e.g., precipitation or changes in tidal currents) on the inferred impact of demolition waste. Comparison with pre-demolition conditions in the previous year (2019) showed that the relative changes in DO, Secchi depth, and pH were very high in 2020, clearly depicting the impact of demolition waste on the water quality of the lake. Match-ups of the turbidity of the water column immediately before and after the demolition using Sentinel 2 data were in good agreement with the in situ data collected. Our study highlights the power of citizen science tools in monitoring lakes and managing water resources and articulates how these activities provide support to Sustainable Development Goal (SDG) targets on Health (Goal 3), Water quality (Goal 6), and Life under the water (Goal 14).

scholarly journals Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes

2012 ◽  
Vol 63 (9) ◽  
pp. 788 ◽  
Author(s):  
N. E. Pettit ◽  
T. D. Jardine ◽  
S. K. Hamilton ◽  
V. Sinnamon ◽  
D. Valdez ◽  
...  
Keyword(s):  
Water Quality ◽  
Seasonal Changes ◽  
Aquatic Macrophyte ◽  
Plant Cover ◽  
Critical Role ◽  
Dry Season ◽  
Nutrient Concentrations ◽  
Wet Season ◽  
Dry Tropics ◽  
The Impact

The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.

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